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Question 1
Incorrect
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A 75-year-old woman with a history of atrial fibrillation presents with a cold and pulseless white arm, indicating a possible brachial embolus. The patient undergoes a brachial embolectomy. What structure is most vulnerable to injury during this procedure?
Your Answer: None of the above
Correct Answer: Median nerve
Explanation:The antecubital fossa is where the brachial artery and median nerve are located in close proximity. Surgeons typically access the brachial artery in this area for embolectomy procedures. However, care must be taken to avoid damaging the median nerve when applying vascular clamps to the artery.
Anatomy of the Brachial Artery
The brachial artery is a continuation of the axillary artery and runs from the lower border of teres major to the cubital fossa where it divides into the radial and ulnar arteries. It is located in the upper arm and has various relations with surrounding structures. Posteriorly, it is related to the long head of triceps with the radial nerve and profunda vessels in between. Anteriorly, it is overlapped by the medial border of biceps. The median nerve crosses the artery in the middle of the arm. In the cubital fossa, the brachial artery is separated from the median cubital vein by the bicipital aponeurosis. The basilic vein is in contact with the most proximal aspect of the cubital fossa and lies medially. Understanding the anatomy of the brachial artery is important for medical professionals when performing procedures such as blood pressure measurement or arterial line placement.
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This question is part of the following fields:
- Neurological System
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Question 2
Correct
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A 99-year-old woman visits her GP complaining of recent facial weakness and slurred speech. The GP suspects a stroke and conducts a thorough neurological evaluation. During the cranial nerve examination, the GP observes that the glossopharyngeal nerve is unaffected. What are the roles and responsibilities of this nerve?
Your Answer: Motor, sensory and autonomic
Explanation:The jugular foramen serves as the pathway for the glossopharyngeal nerve. This nerve has autonomic functions for the parotid gland, motor functions for the stylopharyngeus muscle, and sensory functions for the posterior third of the tongue, palatine tonsils, oropharynx, middle ear mucosa, pharyngeal tympanic tube, and carotid bodies.
Cranial nerves are a set of 12 nerves that emerge from the brain and control various functions of the head and neck. Each nerve has a specific function, such as smell, sight, eye movement, facial sensation, and tongue movement. Some nerves are sensory, some are motor, and some are both. A useful mnemonic to remember the order of the nerves is Some Say Marry Money But My Brother Says Big Brains Matter Most, with S representing sensory, M representing motor, and B representing both.
In addition to their specific functions, cranial nerves also play a role in various reflexes. These reflexes involve an afferent limb, which carries sensory information to the brain, and an efferent limb, which carries motor information from the brain to the muscles. Examples of cranial nerve reflexes include the corneal reflex, jaw jerk, gag reflex, carotid sinus reflex, pupillary light reflex, and lacrimation reflex. Understanding the functions and reflexes of the cranial nerves is important in diagnosing and treating neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 3
Correct
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A 78-year-old male presents to the emergency department with a suspected acute ischaemic stroke. Upon examination, the male displays pendular nystagmus, hypotonia, and an intention tremor primarily in his left hand. During testing, he exhibits hypermetria with his left hand. What is the probable site of the lesion?
Your Answer: Left cerebellum
Explanation:Unilateral cerebellar damage results in ipsilateral symptoms, as seen in the patient in this scenario who is experiencing nystagmus, hypotonia, intention tremor, and hypermetria on the left side following a suspected ischemic stroke. This contrasts with cerebral hemisphere damage, which typically causes contralateral symptoms. A stroke in the left motor cortex, for example, would result in weakness on the right side of the body and face. The right cerebellum is an incorrect answer as it would cause symptoms on the same side of the body, while a stroke in the right motor cortex would cause weakness on the left side. Damage to the occipital lobes, responsible for vision, on the right side would lead to left-sided visual symptoms.
Cerebellar syndrome is a condition that affects the cerebellum, a part of the brain responsible for coordinating movement and balance. When there is damage or injury to one side of the cerebellum, it can cause symptoms on the same side of the body. These symptoms can be remembered using the mnemonic DANISH, which stands for Dysdiadochokinesia, Dysmetria, Ataxia, Nystagmus, Intention tremour, Slurred staccato speech, and Hypotonia.
There are several possible causes of cerebellar syndrome, including genetic conditions like Friedreich’s ataxia and ataxic telangiectasia, neoplastic growths like cerebellar haemangioma, strokes, alcohol use, multiple sclerosis, hypothyroidism, and certain medications or toxins like phenytoin or lead poisoning. In some cases, cerebellar syndrome may be a paraneoplastic condition, meaning it is a secondary effect of an underlying cancer like lung cancer. It is important to identify the underlying cause of cerebellar syndrome in order to provide appropriate treatment and management.
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This question is part of the following fields:
- Neurological System
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Question 4
Correct
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A patient visiting the neurology outpatient clinic presents with a motor deficit. The neurologist observes muscle fasciculations, flaccid weakness, and decreased reflexes.
What is the location of the lesion?Your Answer: Peripheral nerve
Explanation:A lower motor neuron lesion can be identified by a decrease in reflex response.
When a lower motor neuron lesion occurs, it can result in reduced tone, weakness, and muscle fasciculations. These neurons originate in the anterior horn of the spinal cord and connect with the neuromuscular junction.
On the other hand, if the corticospinal tract is affected in the motor cortex, internal capsule, midbrain, or medulla, it would cause an upper motor neuron pattern of weakness. This would be characterized by hypertonia, brisk reflexes, and an upgoing plantar reflex response.
Reflexes are automatic responses that our body makes in response to certain stimuli. These responses are controlled by the nervous system and do not require conscious thought. There are several common reflexes that are associated with specific roots in the spinal cord. For example, the ankle reflex is associated with the S1-S2 root, while the knee reflex is associated with the L3-L4 root. Similarly, the biceps reflex is associated with the C5-C6 root, and the triceps reflex is associated with the C7-C8 root. Understanding these reflexes can help healthcare professionals diagnose and treat certain conditions.
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This question is part of the following fields:
- Neurological System
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Question 5
Correct
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A 35-year-old man suffers a neck stabbing that results in injury to his inferior brachial plexus trunk. Which modality is most likely to remain unaffected?
Your Answer: Initiating abduction of the shoulder
Explanation:The ulnar nerve is primarily affected in cases of injury to the inferior trunk of the brachial plexus, which is composed mainly of nerve roots C8 and T1. The medial cord, which is part of the inferior trunk, also contributes to the median nerve, resulting in some degree of grip impairment. However, such injuries are rare.
Understanding the Brachial Plexus and Cutaneous Sensation of the Upper Limb
The brachial plexus is a network of nerves that originates from the anterior rami of C5 to T1. It is divided into five sections: roots, trunks, divisions, cords, and branches. To remember these sections, a common mnemonic used is Real Teenagers Drink Cold Beer.
The roots of the brachial plexus are located in the posterior triangle and pass between the scalenus anterior and medius muscles. The trunks are located posterior to the middle third of the clavicle, with the upper and middle trunks related superiorly to the subclavian artery. The lower trunk passes over the first rib posterior to the subclavian artery. The divisions of the brachial plexus are located at the apex of the axilla, while the cords are related to the axillary artery.
The branches of the brachial plexus provide cutaneous sensation to the upper limb. This includes the radial nerve, which provides sensation to the posterior arm, forearm, and hand; the median nerve, which provides sensation to the palmar aspect of the thumb, index, middle, and half of the ring finger; and the ulnar nerve, which provides sensation to the palmar and dorsal aspects of the fifth finger and half of the ring finger.
Understanding the brachial plexus and its branches is important in diagnosing and treating conditions that affect the upper limb, such as nerve injuries and neuropathies. It also helps in understanding the cutaneous sensation of the upper limb and how it relates to the different nerves of the brachial plexus.
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This question is part of the following fields:
- Neurological System
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Question 6
Incorrect
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A 23-year-old man is involved in a physical altercation and suffers a stab wound in his upper forearm. Upon examination, a small yet deep laceration is observed. There is an evident loss of pincer movement in the thumb and index finger, with minimal sensation loss. Which nerve is most likely to have been injured?
Your Answer: Median nerve
Correct Answer: Anterior interosseous nerve
Explanation:The median nerve gives rise to the anterior interosseous nerve, which is a motor branch located below the elbow. If this nerve is injured, it typically results in the following symptoms: pain in the forearm, inability to perform pincer movements with the thumb and index finger (as it controls the long flexor muscles of the flexor pollicis longus and flexor digitorum profundus of the index and middle finger), and minimal loss of sensation due to the absence of a cutaneous branch.
Anatomy and Function of the Median Nerve
The median nerve is a nerve that originates from the lateral and medial cords of the brachial plexus. It descends lateral to the brachial artery and passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. The nerve then passes between the two heads of the pronator teres muscle and runs on the deep surface of flexor digitorum superficialis. Near the wrist, it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, passing deep to the flexor retinaculum to enter the palm.
The median nerve has several branches that supply the upper arm, forearm, and hand. These branches include the pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, flexor pollicis longus, and palmar cutaneous branch. The nerve also provides motor supply to the lateral two lumbricals, opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis muscles, as well as sensory supply to the palmar aspect of the lateral 2 ½ fingers.
Damage to the median nerve can occur at the wrist or elbow, resulting in various symptoms such as paralysis and wasting of thenar eminence muscles, weakness of wrist flexion, and sensory loss to the palmar aspect of the fingers. Additionally, damage to the anterior interosseous nerve, a branch of the median nerve, can result in loss of pronation of the forearm and weakness of long flexors of the thumb and index finger. Understanding the anatomy and function of the median nerve is important in diagnosing and treating conditions that affect this nerve.
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This question is part of the following fields:
- Neurological System
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Question 7
Correct
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A teenage boy is struck on the side of his head by a baseball bat. Upon CT head scan, an extradural haematoma is detected. What is the most probable foramen that the affected artery entered the skull through?
Your Answer: Foramen spinosum
Explanation:The artery that is most likely responsible for the extradural haematoma is the middle meningeal artery, which enters the skull through the foramen spinosum. This artery is vulnerable to injury in the pterional region of the skull, where the bone is thin and can be easily fractured. The accessory meningeal artery enters through the foramen ovale, while the carotid artery enters through the carotid canal and the recurrent meningeal artery enters through the superior orbital fissure. The foramen rotundum does not have an artery entering through it.
Foramina of the Base of the Skull
The base of the skull contains several openings called foramina, which allow for the passage of nerves, blood vessels, and other structures. The foramen ovale, located in the sphenoid bone, contains the mandibular nerve, otic ganglion, accessory meningeal artery, and emissary veins. The foramen spinosum, also in the sphenoid bone, contains the middle meningeal artery and meningeal branch of the mandibular nerve. The foramen rotundum, also in the sphenoid bone, contains the maxillary nerve.
The foramen lacerum, located in the sphenoid bone, is initially occluded by a cartilaginous plug and contains the internal carotid artery, nerve and artery of the pterygoid canal, and the base of the medial pterygoid plate. The jugular foramen, located in the temporal bone, contains the inferior petrosal sinus, glossopharyngeal, vagus, and accessory nerves, sigmoid sinus, and meningeal branches from the occipital and ascending pharyngeal arteries.
The foramen magnum, located in the occipital bone, contains the anterior and posterior spinal arteries, vertebral arteries, and medulla oblongata. The stylomastoid foramen, located in the temporal bone, contains the stylomastoid artery and facial nerve. Finally, the superior orbital fissure, located in the sphenoid bone, contains the oculomotor nerve, recurrent meningeal artery, trochlear nerve, lacrimal, frontal, and nasociliary branches of the ophthalmic nerve, and abducent nerve.
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This question is part of the following fields:
- Neurological System
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Question 8
Correct
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A 12-year-old boy comes to the GP after experiencing unusual behavior. His mother accompanies him and reports that her son suddenly started smacking his lips together for a brief period. She adds that he then complained of smelling a foul odor that she couldn't detect. Given the family history of epilepsy, you suspect that he may have had a seizure. What type of seizure is typically associated with these symptoms?
Your Answer: Temporal lobe seizure
Explanation:Temporal lobe seizures can lead to hallucinations, including olfactory hallucinations, which is likely the cause of this patient’s presentation.
Flashes and floaters are a common symptom of occipital lobe seizures.
Juvenile myoclonic epilepsy can cause occasional generalized seizures and daytime absences.
Parietal lobe seizures can result in paraesthesia.
Localising Features of Focal Seizures in Epilepsy
Focal seizures in epilepsy can be localised based on the specific location of the brain where they occur. Temporal lobe seizures are common and may occur with or without impairment of consciousness or awareness. Most patients experience an aura, which is typically a rising epigastric sensation, along with psychic or experiential phenomena such as déjà vu or jamais vu. Less commonly, hallucinations may occur, such as auditory, gustatory, or olfactory hallucinations. These seizures typically last around one minute and are often accompanied by automatisms, such as lip smacking, grabbing, or plucking.
On the other hand, frontal lobe seizures are characterised by motor symptoms such as head or leg movements, posturing, postictal weakness, and Jacksonian march. Parietal lobe seizures, on the other hand, are sensory in nature and may cause paraesthesia. Finally, occipital lobe seizures may cause visual symptoms such as floaters or flashes. By identifying the specific location and type of seizure, doctors can better diagnose and treat epilepsy in patients.
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This question is part of the following fields:
- Neurological System
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Question 9
Incorrect
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A 25-year-old man is having an inguinal hernia repair done with local anaesthesia. During the surgery, the surgeon comes across a bleeding site and uses diathermy to manage it. After a minute or so, the patient reports feeling a burning pain from the heat at the surgical site. Which type of nerve fibers are responsible for transmitting this signal?
Your Answer: A α fibres
Correct Answer: C fibres
Explanation:Mechanothermal stimuli are transmitted slowly through C fibres, while A α fibres transmit motor proprioception information, A β fibres transmit touch and pressure information, and B fibres are responsible for autonomic functions.
Neurons and Synaptic Signalling
Neurons are the building blocks of the nervous system and are made up of dendrites, a cell body, and axons. They can be classified by their anatomical structure, axon width, and function. Neurons communicate with each other at synapses, which consist of a presynaptic membrane, synaptic gap, and postsynaptic membrane. Neurotransmitters are small chemical messengers that diffuse across the synaptic gap and activate receptors on the postsynaptic membrane. Different neurotransmitters have different effects, with some causing excitation and others causing inhibition. The deactivation of neurotransmitters varies, with some being degraded by enzymes and others being reuptaken by cells. Understanding the mechanisms of neuronal communication is crucial for understanding the functioning of the nervous system.
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This question is part of the following fields:
- Neurological System
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Question 10
Incorrect
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A 35-year-old man is brought to the emergency department with suspected spinal trauma following a car accident. He presents with back pain and pain in his right leg. Initial vital signs reveal a blood pressure of 125/83 mmHg and a heart rate of 83bpm. Upon examination, there is bruising on his chest and an obvious deformity in his right leg. Later that day, he suddenly experiences a severe headache and appears flushed, sweating profusely. His vital signs now show a blood pressure of 162/97mmHg and a heart rate of 51. What is the level of his injury?
Your Answer: L1
Correct Answer: T5
Explanation:Autonomic dysreflexia can occur if the spinal cord injury is at or above the T5 level. This condition is characterized by symptoms such as headache, sweating, hypertension, and bradycardia, which can be triggered by any afferent sympathetic signal, such as urinary retention or faecal impaction. A spinal injury at the level of L1 or S1 is too low to cause autonomic dysreflexia, but may affect bladder and bowel control and the use of the hip and legs.
Autonomic dysreflexia is a condition that occurs in patients who have suffered a spinal cord injury at or above the T6 spinal level. It is caused by a reflex response triggered by various stimuli, such as faecal impaction or urinary retention, which sends signals through the thoracolumbar outflow. However, due to the spinal cord lesion, the usual parasympathetic response is prevented, leading to an unbalanced physiological response. This response is characterized by extreme hypertension, flushing, and sweating above the level of the cord lesion, as well as agitation. If left untreated, severe consequences such as haemorrhagic stroke can occur. The management of autonomic dysreflexia involves removing or controlling the stimulus and treating any life-threatening hypertension and/or bradycardia.
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This question is part of the following fields:
- Neurological System
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Question 11
Correct
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A 65 year old man is scheduled for a lymph node biopsy on the posterolateral aspect of his right neck due to suspected lymphoma. Which nerve is most vulnerable in this procedure?
Your Answer: Accessory
Explanation:The accessory nerve is at risk of injury due to its superficial location and proximity to the platysma muscle. It may be divided during the initial stages of a procedure.
The Accessory Nerve and Its Functions
The accessory nerve is the eleventh cranial nerve that provides motor innervation to the sternocleidomastoid and trapezius muscles. It is important to examine the function of this nerve by checking for any loss of muscle bulk in the shoulders, asking the patient to shrug their shoulders against resistance, and turning their head against resistance.
Iatrogenic injury, which is caused by medical treatment or procedures, is a common cause of isolated accessory nerve lesions. This is especially true for surgeries in the posterior cervical triangle, such as lymph node biopsy. It is important to be aware of the potential for injury to the accessory nerve during these procedures to prevent any long-term complications.
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This question is part of the following fields:
- Neurological System
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Question 12
Correct
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During a challenging femoro-popliteal bypass surgery, the surgeon mistakenly applies a clamp on the femoral nerve. The clamp remains in place for a significant portion of the procedure. Upon examination after the operation, the nerve is found to be intact but shows signs of compression. What is the most probable outcome in the coming months?
Your Answer: Wallerian degeneration
Explanation:Despite the nerve remaining intact, a neuronal injury can lead to Wallerian degeneration and potentially the formation of neuromas.
Nerve injuries can be classified into three types: neuropraxia, axonotmesis, and neurotmesis. Neuropraxia occurs when the nerve is intact but its electrical conduction is affected. However, full recovery is possible, and autonomic function is preserved. Wallerian degeneration, which is the degeneration of axons distal to the site of injury, does not occur. Axonotmesis, on the other hand, happens when the axon is damaged, but the myelin sheath is preserved, and the connective tissue framework is not affected. Wallerian degeneration occurs in this type of injury. Lastly, neurotmesis is the most severe type of nerve injury, where there is a disruption of the axon, myelin sheath, and surrounding connective tissue. Wallerian degeneration also occurs in this type of injury.
Wallerian degeneration typically begins 24-36 hours following the injury. Axons are excitable before degeneration occurs, and the myelin sheath degenerates and is phagocytosed by tissue macrophages. Neuronal repair may only occur physiologically where nerves are in direct contact. However, nerve regeneration may be hampered when a large defect is present, and it may not occur at all or result in the formation of a neuroma. If nerve regrowth occurs, it typically happens at a rate of 1mm per day.
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This question is part of the following fields:
- Neurological System
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Question 13
Incorrect
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A 72-year-old male comes to the emergency department with sudden onset left sided hemiparesis and speech difficulties. There is no sensory loss. During the examination, you observe weakness in the left upper limb. Although she nods to indicate understanding, her responses are slow and difficult. You suspect a stroke.
What is the most probable location of the lesion in the brain?Your Answer: Superior frontal gyrus
Correct Answer: Inferior frontal gyrus
Explanation:Broca’s aphasia is caused by a lesion in the inferior frontal gyrus, leading to non-fluent and laboured speech. On the other hand, Wernicke’s aphasia is caused by a lesion in the superior frontal gyrus, resulting in fluent but nonsensical speech. The arcuate fasciculus connects these two areas, and a lesion in this connection can cause fluent speech with poor repetition. A lesion in the primary motor cortex causes contralateral motor deficits, while a lesion in the cerebellum results in slurred speech, horizontal nystagmus, intention tremors, and an ataxic gait.
Types of Aphasia: Understanding the Different Forms of Language Impairment
Aphasia is a language disorder that affects a person’s ability to communicate effectively. There are different types of aphasia, each with its own set of symptoms and underlying causes. Wernicke’s aphasia, also known as receptive aphasia, is caused by a lesion in the superior temporal gyrus. This area is responsible for forming speech before sending it to Broca’s area. People with Wernicke’s aphasia may speak fluently, but their sentences often make no sense, and they may use word substitutions and neologisms. Comprehension is impaired.
Broca’s aphasia, also known as expressive aphasia, is caused by a lesion in the inferior frontal gyrus. This area is responsible for speech production. People with Broca’s aphasia may speak in a non-fluent, labored, and halting manner. Repetition is impaired, but comprehension is normal.
Conduction aphasia is caused by a stroke affecting the arcuate fasciculus, the connection between Wernicke’s and Broca’s area. People with conduction aphasia may speak fluently, but their repetition is poor. They are aware of the errors they are making, but comprehension is normal.
Global aphasia is caused by a large lesion affecting all three areas mentioned above, resulting in severe expressive and receptive aphasia. People with global aphasia may still be able to communicate using gestures. Understanding the different types of aphasia is important for proper diagnosis and treatment.
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This question is part of the following fields:
- Neurological System
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Question 14
Correct
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A 20-year-old man is rushed to the emergency department following his ejection from a car during a road accident.
During the examination, the patient responds to simple questions with incomprehensible sounds and opens his eyes in response to pain. There is also an abnormal wrist flexion when a sternal rub is applied, and a positive Battle's sign is observed.
A CT scan of the head is ordered, which reveals a fracture of the petrous temporal bone.
Which nerve is most likely to be affected by the patient's injury?Your Answer: Facial nerve
Explanation:The facial nerve passes through the internal acoustic meatus, which is correct. This nerve provides motor innervation to the muscles of facial expression, parasympathetic innervation to salivary and lacrimal glands, and special sensory innervation of taste in the anterior 2/3 of the tongue via the chorda tympani. The patient in question has a Glasgow Coma Score of 7, indicating nonspecific neurotrauma from a recent road traffic accident. It is unlikely that damage to the internal acoustic meatus would affect the glossopharyngeal or hypoglossal nerves, which pass through different structures. Damage to the oculomotor nerve, which passes through the superior orbital fissure, may cause ptosis and a dilated ‘down-and-out’ pupil.
Cranial nerves are a set of 12 nerves that emerge from the brain and control various functions of the head and neck. Each nerve has a specific function, such as smell, sight, eye movement, facial sensation, and tongue movement. Some nerves are sensory, some are motor, and some are both. A useful mnemonic to remember the order of the nerves is Some Say Marry Money But My Brother Says Big Brains Matter Most, with S representing sensory, M representing motor, and B representing both.
In addition to their specific functions, cranial nerves also play a role in various reflexes. These reflexes involve an afferent limb, which carries sensory information to the brain, and an efferent limb, which carries motor information from the brain to the muscles. Examples of cranial nerve reflexes include the corneal reflex, jaw jerk, gag reflex, carotid sinus reflex, pupillary light reflex, and lacrimation reflex. Understanding the functions and reflexes of the cranial nerves is important in diagnosing and treating neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 15
Correct
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A 87-year-old man complains of a headache and hearing loss. Although he frequently experiences headaches, this time it feels different, and he cannot hear anyone on his right side. During the examination, a sensorineural hearing loss is observed in the right ear, but nothing else is noteworthy.
A CT scan of the head reveals no acute bleeding, but an MRI scan shows an ischemic area surrounding the thalamus on the right side.
What is the probable location of the lesion in the thalamus?Your Answer: Medial geniculate nucleus
Explanation:Hearing impairment can be caused by damage to the medial geniculate nucleus of the thalamus.
The Thalamus: Relay Station for Motor and Sensory Signals
The thalamus is a structure located between the midbrain and cerebral cortex that serves as a relay station for motor and sensory signals. Its main function is to transmit these signals to the cerebral cortex, which is responsible for processing and interpreting them. The thalamus is composed of different nuclei, each with a specific function. The lateral geniculate nucleus relays visual signals, while the medial geniculate nucleus transmits auditory signals. The medial portion of the ventral posterior nucleus (VML) is responsible for facial sensation, while the ventral anterior/lateral nuclei relay motor signals. Finally, the lateral portion of the ventral posterior nucleus is responsible for body sensation, including touch, pain, proprioception, pressure, and vibration. Overall, the thalamus plays a crucial role in the transmission of sensory and motor information to the brain, allowing us to perceive and interact with the world around us.
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This question is part of the following fields:
- Neurological System
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Question 16
Incorrect
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Samantha is a 65-year-old alcoholic who has come to her doctor with worries about the feeling in her legs. She is experiencing decreased light-touch sensation and proprioception in both legs. Her blood work reveals a deficiency in vitamin B12.
What signs are most probable for you to observe in Samantha?Your Answer: Gums which easily bleed
Correct Answer: Positive Babinski sign
Explanation:The presence of a positive Babinski sign may indicate subacute degeneration of the spinal cord, which is typically caused by a deficiency in vitamin B12. This condition primarily affects the dorsal columns of the spinal cord, which are responsible for fine-touch, proprioception, and vibration sensation. In addition to the Babinski sign, patients may also experience spastic paresis. However, hypotonia is not typically observed, as this is a characteristic of lower motor neuron lesions. It is also important to note that temperature sensation is not affected by subacute degeneration of the spinal cord, as this function is mediated by the spinothalamic tract.
Subacute Combined Degeneration of Spinal Cord
Subacute combined degeneration of spinal cord is a condition that occurs due to a deficiency of vitamin B12. The dorsal columns and lateral corticospinal tracts are affected, leading to the loss of joint position and vibration sense. The first symptoms are usually distal paraesthesia, followed by the development of upper motor neuron signs in the legs, such as extensor plantars, brisk knee reflexes, and absent ankle jerks. If left untreated, stiffness and weakness may persist.
This condition is a serious concern and requires prompt medical attention. It is important to maintain a healthy diet that includes sufficient amounts of vitamin B12 to prevent the development of subacute combined degeneration of spinal cord.
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This question is part of the following fields:
- Neurological System
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Question 17
Correct
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In what area is a lumbar puncture typically conducted?
Your Answer: Subarachnoid space
Explanation:To obtain samples of CSF, a needle is typically inserted between the third and fourth lumbar vertebrae, with the tip placed in the subarachnoid space. It is important to note that the spinal cord ends at L1 and is not at risk of harm during this procedure. However, if there is clinical evidence of increased intracranial pressure, lumbar puncture should not be performed.
Cerebrospinal Fluid: Circulation and Composition
Cerebrospinal fluid (CSF) is a clear, colorless liquid that fills the space between the arachnoid mater and pia mater, covering the surface of the brain. The total volume of CSF in the brain is approximately 150ml, and it is produced by the ependymal cells in the choroid plexus or blood vessels. The majority of CSF is produced by the choroid plexus, accounting for 70% of the total volume. The remaining 30% is produced by blood vessels. The CSF is reabsorbed via the arachnoid granulations, which project into the venous sinuses.
The circulation of CSF starts from the lateral ventricles, which are connected to the third ventricle via the foramen of Munro. From the third ventricle, the CSF flows through the cerebral aqueduct (aqueduct of Sylvius) to reach the fourth ventricle via the foramina of Magendie and Luschka. The CSF then enters the subarachnoid space, where it circulates around the brain and spinal cord. Finally, the CSF is reabsorbed into the venous system via arachnoid granulations into the superior sagittal sinus.
The composition of CSF is essential for its proper functioning. The glucose level in CSF is between 50-80 mg/dl, while the protein level is between 15-40 mg/dl. Red blood cells are not present in CSF, and the white blood cell count is usually less than 3 cells/mm3. Understanding the circulation and composition of CSF is crucial for diagnosing and treating various neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 18
Incorrect
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A 89-year-old man is brought to his primary care physician by his daughter who is worried about changes in his behavior following a stroke 10 weeks ago. The daughter reports that the man has gained 12 kg in the past 8 weeks and appears to be constantly putting household items in his mouth. He also struggles to identify familiar people and objects. During the appointment, the man mentions that his sex drive has significantly increased.
Which specific area of the brain has been affected by the lesion?Your Answer: Hippocampus
Correct Answer: Amygdala
Explanation:Kluver-Bucy syndrome is often caused by bilateral lesions in the medial temporal lobe, including the amygdala. This can lead to symptoms such as hyperorality, hypersexuality, hyperphagia, and visual agnosia. Lesions in the cingulate gyrus can result in poor decision-making and emotional dysfunction, while frontal lobe lesions can cause changes in behavior, anosmia, aphasia, and motor impairment. Hippocampus lesions can lead to memory impairment, and thalamic lesions can result in sensory and motor dysfunction.
Brain lesions can be localized based on the neurological disorders or features that are present. The gross anatomy of the brain can provide clues to the location of the lesion. For example, lesions in the parietal lobe can result in sensory inattention, apraxias, astereognosis, inferior homonymous quadrantanopia, and Gerstmann’s syndrome. Lesions in the occipital lobe can cause homonymous hemianopia, cortical blindness, and visual agnosia. Temporal lobe lesions can result in Wernicke’s aphasia, superior homonymous quadrantanopia, auditory agnosia, and prosopagnosia. Lesions in the frontal lobes can cause expressive aphasia, disinhibition, perseveration, anosmia, and an inability to generate a list. Lesions in the cerebellum can result in gait and truncal ataxia, intention tremor, past pointing, dysdiadokinesis, and nystagmus.
In addition to the gross anatomy, specific areas of the brain can also provide clues to the location of a lesion. For example, lesions in the medial thalamus and mammillary bodies of the hypothalamus can result in Wernicke and Korsakoff syndrome. Lesions in the subthalamic nucleus of the basal ganglia can cause hemiballism, while lesions in the striatum (caudate nucleus) can result in Huntington chorea. Parkinson’s disease is associated with lesions in the substantia nigra of the basal ganglia, while lesions in the amygdala can cause Kluver-Bucy syndrome, which is characterized by hypersexuality, hyperorality, hyperphagia, and visual agnosia. By identifying these specific conditions, doctors can better localize brain lesions and provide appropriate treatment.
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This question is part of the following fields:
- Neurological System
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Question 19
Correct
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A 65-year-old patient reports to their physician with a complaint of taste loss. After taking a thorough medical history, the doctor notes no recent infections. However, the patient does mention being able to taste normally when only using the tip of their tongue, such as when licking ice cream.
Which cranial nerve is impacted in this situation?Your Answer: Glossopharyngeal nerve
Explanation:The loss of taste in the posterior third of the tongue is due to a problem with the glossopharyngeal nerve (CN IX). This is because the patient can taste when licking the ice cream, indicating that the anterior two-thirds of the tongue are functioning normally. The facial nerve also provides taste sensation, but only to the anterior two-thirds of the tongue, so it is not responsible for the loss of taste in the posterior third. The hypoglossal nerve is not involved in taste sensation, but rather in motor innervation of the tongue. The olfactory nerve innervates the nose, not the tongue, and there is no indication of a problem with the patient’s sense of smell.
Cranial nerves are a set of 12 nerves that emerge from the brain and control various functions of the head and neck. Each nerve has a specific function, such as smell, sight, eye movement, facial sensation, and tongue movement. Some nerves are sensory, some are motor, and some are both. A useful mnemonic to remember the order of the nerves is Some Say Marry Money But My Brother Says Big Brains Matter Most, with S representing sensory, M representing motor, and B representing both.
In addition to their specific functions, cranial nerves also play a role in various reflexes. These reflexes involve an afferent limb, which carries sensory information to the brain, and an efferent limb, which carries motor information from the brain to the muscles. Examples of cranial nerve reflexes include the corneal reflex, jaw jerk, gag reflex, carotid sinus reflex, pupillary light reflex, and lacrimation reflex. Understanding the functions and reflexes of the cranial nerves is important in diagnosing and treating neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 20
Incorrect
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A 22-year-old individual is brought to the medical team on call due to fever, neck stiffness, and altered Glasgow coma scale. The medical team suspects acute bacterial meningitis.
What would be the most suitable antibiotic option for this patient?Your Answer: Ciprofloxacin
Correct Answer: Cefotaxime
Explanation:Empirical Antibiotic Treatment for Acute Bacterial Meningitis
Patients aged 16-50 years presenting with acute bacterial meningitis are most likely infected with Neisseria meningitidis or Streptococcus pneumoniae. The most appropriate empirical antibiotic choice for this age group is cefotaxime alone. However, if the patient has been outside the UK recently or has had multiple courses of antibiotics in the last 3 months, vancomycin may be added due to the increase in penicillin-resistant pneumococci worldwide.
For infants over 3 months old up to adults of 50 years old, cefotaxime is the preferred antibiotic. If the patient is under 3 months or over 50 years old, amoxicillin is added to cover for Listeria monocytogenes meningitis, although this is rare. Ceftriaxone can be used instead of cefotaxime.
Once the results of culture and sensitivity are available, the antibiotic choice can be modified for optimal treatment. Benzylpenicillin is usually first line, but it is not an option in this case. It is important to choose the appropriate antibiotic treatment to ensure the best possible outcome for the patient.
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This question is part of the following fields:
- Neurological System
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Question 21
Incorrect
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A 60-year-old man visits an after-hours medical facility in the late evening with a complaint of a severe headache that is focused around his left eye. He mentions experiencing haloes in his vision and difficulty seeing clearly. The patient has a medical history of hypertension and diabetes. During the examination, the sclera appears red, and the cornea is hazy with a dilated pupil.
What condition is the most probable diagnosis?Your Answer: Subarachnoid haemorrhage
Correct Answer: Acute closed-angle glaucoma
Explanation:The patient’s symptoms are consistent with acute closed-angle glaucoma, which is an urgent ophthalmological emergency. They are experiencing a headache with unilateral eye pain, reduced vision, visual haloes, a red and congested eye with a cloudy cornea, and a dilated, unresponsive pupil. These symptoms may be triggered by darkness or dilating eye drops. Treatment should involve laying the patient flat to relieve angle pressure, administering pilocarpine eye drops to constrict the pupil, acetazolamide orally to reduce aqueous humour production, and providing analgesia. Referral to secondary care is necessary.
It is important to differentiate this condition from other potential causes of the patient’s symptoms. Central retinal vein occlusion, for example, would cause sudden painless loss of vision and severe retinal haemorrhages on fundoscopy. Migraines typically involve a visual or somatosensory aura followed by a unilateral throbbing headache, nausea, vomiting, and photophobia. Subarachnoid haemorrhages present with a sudden, severe headache, rather than a gradually worsening one accompanied by eye signs. Temporal arteritis may cause pain when chewing, difficulty brushing hair, and thickened temporal arteries visible on examination. However, the presence of a dilated, fixed pupil with conjunctival injection should steer the clinician away from a diagnosis of migraine.
Acute angle closure glaucoma (AACG) is a type of glaucoma where there is a rise in intraocular pressure (IOP) due to a blockage in the outflow of aqueous humor. This condition is more likely to occur in individuals with hypermetropia, pupillary dilation, and lens growth associated with aging. Symptoms of AACG include severe pain, decreased visual acuity, a hard and red eye, haloes around lights, and a semi-dilated non-reacting pupil. AACG is an emergency and requires urgent referral to an ophthalmologist. The initial medical treatment involves a combination of eye drops, such as a direct parasympathomimetic, a beta-blocker, and an alpha-2 agonist, as well as intravenous acetazolamide to reduce aqueous secretions. Definitive management involves laser peripheral iridotomy, which creates a tiny hole in the peripheral iris to allow aqueous humor to flow to the angle.
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This question is part of the following fields:
- Neurological System
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Question 22
Correct
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A 50-year-old man is brought to the hospital by the police after being found unconscious on the street. He appears disheveled and smells strongly of alcohol. Despite attempts to gather information about his medical history, none is available. Upon examination, his temperature is 35°C, blood pressure is 106/72 mmHg, and pulse is 52 bpm. He does not respond to commands, but when a venflon is attempted, he tries to grab the arm of the medical professional and makes incomprehensible sounds while keeping his eyes closed. What is his Glasgow coma scale score?
Your Answer: 8
Explanation:The Glasgow Coma Scale: A Simple and Reliable Tool for Assessing Brain Injury
The Glasgow Coma Scale (GCS) is a widely used tool for assessing the severity of brain injury. It is simple to use, has a high degree of interobserver reliability, and is strongly correlated with patient outcomes. The GCS consists of three components: Eye Opening (E), Verbal Response (V), and Motor Response (M). Each component is scored on a scale of 1 to 6, with higher scores indicating better function.
The Eye Opening component assesses the patient’s ability to open their eyes spontaneously or in response to verbal or painful stimuli. The Verbal Response component evaluates the patient’s ability to speak and communicate appropriately. The Motor Response component assesses the patient’s ability to move their limbs in response to verbal or painful stimuli.
The GCS score is calculated by adding the scores for each component. A score of 15 indicates normal brain function, while a score of 3 or less indicates severe brain injury. The GCS score is an important prognostic indicator, as it can help predict patient outcomes and guide treatment decisions.
In summary, the Glasgow Coma Scale is a simple and reliable tool for assessing brain injury. It consists of three components that evaluate eye opening, verbal response, and motor response. The GCS score is calculated by adding the scores for each component and can help predict patient outcomes.
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This question is part of the following fields:
- Neurological System
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Question 23
Incorrect
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A young man presents after multiple episodes of optic neuritis, during which he develops unilateral eye pain. Upon examination, he is found to have decreased visual acuity and colour saturation on his affected eye. His doctor suspects multiple sclerosis. What features would be expected on a T2-weighted MRI?
Your Answer: Unilateral semilunar lesion
Correct Answer: Multiple hyperintense lesions
Explanation:MS is characterized by the spread of brain lesions over time and space.
Dementia is often linked to cortical atrophy.
If there is only one hyperintense lesion, it may indicate a haemorrhage rather than other conditions.
A semilunar lesion on one side may indicate a subdural haemorrhage.
Raised intracranial pressure, which can be caused by space-occupying lesions and haemorrhages, can be indicated by midline shift.
Investigating Multiple Sclerosis
Diagnosing multiple sclerosis (MS) requires the identification of lesions that are disseminated in both time and space. There are several methods used to investigate MS, including magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) analysis, and visual evoked potentials (VEP).
MRI is a commonly used tool to identify MS lesions. High signal T2 lesions and periventricular plaques are often observed, as well as Dawson fingers, which are hyperintense lesions perpendicular to the corpus callosum. CSF analysis can also aid in diagnosis, as it may reveal oligoclonal bands that are not present in serum and an increased intrathecal synthesis of IgG.
VEP testing can also be used to diagnose MS. This test measures the electrical activity in the visual pathway and can reveal a delayed but well-preserved waveform in MS patients.
Overall, a combination of these methods is often used to diagnose MS and demonstrate the dissemination of lesions in time and space.
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This question is part of the following fields:
- Neurological System
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Question 24
Correct
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A 35-year-old female comes to your clinic complaining of a headache that she characterizes as a 'tight-band' around her head. The pain is present on both sides of her head. She reports no accompanying nausea or vomiting. There are no auras or any radiation of the pain down her neck or onto her eyes.
What is the initial treatment of choice for this condition based on the probable diagnosis?Your Answer: Aspirin
Explanation:First-line treatment for tension headaches includes aspirin, paracetamol, or an NSAID. Sumatriptan is typically prescribed for migraines, while high-flow oxygen is used to treat cluster headaches. Prophylaxis for tension headaches may involve low-dose amitriptyline.
Tension-type headache is a type of primary headache that is characterized by a sensation of pressure or a tight band around the head. Unlike migraine, tension-type headache is typically bilateral and of lower intensity. It is not associated with aura, nausea/vomiting, or physical activity. Stress may be a contributing factor, and it can coexist with migraine. Chronic tension-type headache is defined as occurring on 15 or more days per month.
The National Institute for Health and Care Excellence (NICE) has produced guidelines for managing tension-type headache. For acute treatment, aspirin, paracetamol, or an NSAID are recommended as first-line options. For prophylaxis, NICE suggests up to 10 sessions of acupuncture over 5-8 weeks. Low-dose amitriptyline is commonly used in the UK for prophylaxis, but the 2012 NICE guidelines do not support this approach. The guidelines state that there is not enough evidence to recommend pharmacological prophylactic treatment for tension-type headache, and that pure tension-type headache requiring prophylaxis is rare. Assessment may uncover coexisting migraine symptomatology with a possible diagnosis of chronic migraine.
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This question is part of the following fields:
- Neurological System
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Question 25
Incorrect
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A 36-year-old woman is referred to neurology clinic by her GP due to a 2-month history of gradual onset numbness in both feet. She has a medical history of well-controlled Crohn's disease on a vegan diet.
During examination, the patient's gait is ataxic and Romberg's test is positive. There is a loss of proprioception and vibration sense to the mid shin bilaterally. Bilateral plantars are upgoing with absent ankle jerks.
Based on these findings, you suspect the patient has subacute combined degeneration of the spinal cord. Which part of the nervous system is affected?Your Answer: The posterior and anterior spinocerebellar tracts of the spinal cord
Correct Answer: The dorsal column and lateral corticospinal tracts of the spinal cord
Explanation:Subacute combined degeneration of the spinal cord is caused by a deficiency in vitamin B12, which is absorbed in the terminal ileum along with intrinsic factor. Individuals at high risk of vitamin B12 deficiency include those with a history of gastric or intestinal surgery, pernicious anemia, malabsorption (especially in Crohn’s disease), and vegans due to decreased dietary intake. Medications such as proton-pump inhibitors and metformin can also reduce absorption of vitamin B12.
SACD primarily affects the dorsal columns and lateral corticospinal tracts of the spinal cord, resulting in the loss of proprioception and vibration sense, followed by distal paraesthesia. The condition typically presents with a combination of upper and lower motor neuron signs, including extensor plantars, brisk knee reflexes, and absent ankle jerks. Treatment with vitamin B12 can result in partial to full recovery, depending on the extent and duration of neurodegeneration.
If a patient has both vitamin B12 and folic acid deficiency, it is important to treat the vitamin B12 deficiency first to prevent the onset of subacute combined degeneration of the cord.
Subacute Combined Degeneration of Spinal Cord
Subacute combined degeneration of spinal cord is a condition that occurs due to a deficiency of vitamin B12. The dorsal columns and lateral corticospinal tracts are affected, leading to the loss of joint position and vibration sense. The first symptoms are usually distal paraesthesia, followed by the development of upper motor neuron signs in the legs, such as extensor plantars, brisk knee reflexes, and absent ankle jerks. If left untreated, stiffness and weakness may persist.
This condition is a serious concern and requires prompt medical attention. It is important to maintain a healthy diet that includes sufficient amounts of vitamin B12 to prevent the development of subacute combined degeneration of spinal cord.
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This question is part of the following fields:
- Neurological System
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Question 26
Correct
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A 65-year-old man has recently undergone parotidectomy on his left side due to a malignant parotid gland tumor. He has been back on the surgical ward for a few hours when he reports feeling weakness on the left side of his mouth. Upon examination, you observe facial asymmetry and weakness on the left side. He is unable to hold air under pressure in his mouth and cannot raise his left lip to show his teeth. This complication is likely due to damage to which nerve?
Your Answer: Facial nerve
Explanation:The facial nerve is the seventh cranial nerve and innervates the muscles of facial expression. It runs through the parotid gland and can be injured during parotidectomy. The maxillary nerve is the second division of the trigeminal nerve and carries sensory fibres from the lower eyelid, cheeks, upper teeth, palate, nasal cavity, and paranasal sinuses. The glossopharyngeal nerve is the ninth cranial nerve and has various functions, including carrying taste and sensation from the posterior third of the tongue and supplying parasympathetic innervation to the parotid gland. The mandibular nerve is the third division of the trigeminal nerve and carries sensory and motor fibres, supplying motor innervation to the muscles of mastication. The hypoglossal nerve is the twelfth cranial nerve and supplies the intrinsic muscles of the tongue.
The facial nerve is responsible for supplying the muscles of facial expression, the digastric muscle, and various glandular structures. It also contains a few afferent fibers that originate in the genicular ganglion and are involved in taste. Bilateral facial nerve palsy can be caused by conditions such as sarcoidosis, Guillain-Barre syndrome, Lyme disease, and bilateral acoustic neuromas. Unilateral facial nerve palsy can be caused by these conditions as well as lower motor neuron issues like Bell’s palsy and upper motor neuron issues like stroke.
The upper motor neuron lesion typically spares the upper face, specifically the forehead, while a lower motor neuron lesion affects all facial muscles. The facial nerve’s path includes the subarachnoid path, where it originates in the pons and passes through the petrous temporal bone into the internal auditory meatus with the vestibulocochlear nerve. The facial canal path passes superior to the vestibule of the inner ear and contains the geniculate ganglion at the medial aspect of the middle ear. The stylomastoid foramen is where the nerve passes through the tympanic cavity anteriorly and the mastoid antrum posteriorly, and it also includes the posterior auricular nerve and branch to the posterior belly of the digastric and stylohyoid muscle.
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This question is part of the following fields:
- Neurological System
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Question 27
Incorrect
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A 32-year-old man is brought to the emergency department by the paramedics. His airway is clear, and he is not experiencing any respiratory or cardiac distress. He states that he was hit by a vehicle while crossing the street.
During the examination, there is significant swelling in his knee and leg, and he has lost sensation in the plantar area of his foot. He cannot plantarflex his foot and has also lost foot inversion.
Which nerve is most likely to have been damaged?Your Answer: Deep fibular nerve
Correct Answer: Tibial nerve
Explanation:When the tibial nerve is injured, the foot loses its ability to plantarflex and invert. Other nerve injuries can result in loss of sensation or motor function in specific muscles, such as the saphenous nerve causing loss of sensation in the medial leg or the femoral nerve causing loss of hip flexion and knee extension. The inferior gluteal nerve injury can lead to gluteal lurch and loss of hip extension.
The Tibial Nerve: Muscles Innervated and Termination
The tibial nerve is a branch of the sciatic nerve that begins at the upper border of the popliteal fossa. It has root values of L4, L5, S1, S2, and S3. This nerve innervates several muscles, including the popliteus, gastrocnemius, soleus, plantaris, tibialis posterior, flexor hallucis longus, and flexor digitorum brevis. These muscles are responsible for various movements in the lower leg and foot, such as plantar flexion, inversion, and flexion of the toes.
The tibial nerve terminates by dividing into the medial and lateral plantar nerves. These nerves continue to innervate muscles in the foot, such as the abductor hallucis, flexor digitorum brevis, and quadratus plantae. The tibial nerve plays a crucial role in the movement and function of the lower leg and foot, and any damage or injury to this nerve can result in significant impairments in mobility and sensation.
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This question is part of the following fields:
- Neurological System
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Question 28
Correct
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A 60-year-old man visits his doctor complaining of headaches. He reports experiencing scalp pain every morning while combing his hair and feeling fatigued while chewing his food. Upon conducting blood tests, the doctor discovers an elevated ESR. What condition is most likely causing these symptoms?
Your Answer: Giant cell arteritis
Explanation:Different Types of Headaches and Their Characteristics
Giant cell arteritis is a condition that affects older patients and is characterized by a headache and scalp tenderness, along with jaw claudication. The superficial temporal artery is often affected, and if left untreated, it can lead to visual loss. High doses of steroids are required for treatment, and the dose is gradually reduced based on the patient’s symptoms and the ESR.
Idiopathic intracranial hypertension (IIH) is a neurological disorder that causes increased intracranial pressure without a mass legion. Symptoms include a headache, which is often worse in the morning, and visual disturbances. A CT head is used to diagnose the condition, and it is treated with repeated lumbar punctures.
Migraine is a recurrent headache that follows a transient prodromal phase. The headache can be accompanied by photophobia and vomiting and can be triggered by various factors such as chocolate and cheese.
Subarachnoid hemorrhage (SAH) is characterized by the worst headache that patients have ever experienced, along with confusion and vomiting. Early recognition and referral to neurosurgery is essential.
Tension headache is a feeling of pressure or tightness around the head, without any associated features.
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This question is part of the following fields:
- Neurological System
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Question 29
Correct
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A 35-year-old man has been referred to the neurology department due to experiencing episodes of visual obstruction with flashes and strange shapes floating over his vision, accompanied by eyelid fluttering. He remains conscious during these episodes. Which brain region is likely to be affected?
Your Answer: Occipital lobe
Explanation:Occipital lobe seizures can cause visual disturbances such as floaters and flashes. This is because the occipital lobe contains the primary visual cortex and visual association cortex, which receive sensory information from the optic radiations. Other symptoms of occipital lobe seizures may include uncontrolled eye movements and eyelid fluttering. It is important to note that seizures in other areas of the brain, such as the frontal or parietal lobes, may present with different symptoms.
Localising Features of Focal Seizures in Epilepsy
Focal seizures in epilepsy can be localised based on the specific location of the brain where they occur. Temporal lobe seizures are common and may occur with or without impairment of consciousness or awareness. Most patients experience an aura, which is typically a rising epigastric sensation, along with psychic or experiential phenomena such as déjà vu or jamais vu. Less commonly, hallucinations may occur, such as auditory, gustatory, or olfactory hallucinations. These seizures typically last around one minute and are often accompanied by automatisms, such as lip smacking, grabbing, or plucking.
On the other hand, frontal lobe seizures are characterised by motor symptoms such as head or leg movements, posturing, postictal weakness, and Jacksonian march. Parietal lobe seizures, on the other hand, are sensory in nature and may cause paraesthesia. Finally, occipital lobe seizures may cause visual symptoms such as floaters or flashes. By identifying the specific location and type of seizure, doctors can better diagnose and treat epilepsy in patients.
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This question is part of the following fields:
- Neurological System
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Question 30
Incorrect
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A laceration of the wrist produces a median nerve transection in a 50-year-old patient. The wound is clean and seen immediately after injury. Collateral soft tissue damage is absent. The patient asks what the prognosis is. You indicate that the nerve should regrow at approximately:
Your Answer: 0.1 mm per day
Correct Answer: 1 mm per day
Explanation:When a peripheral nerve is cut, it causes bleeding and the nerve ends retract. The axon, which is the part of the nerve that transmits signals, starts to degenerate immediately after the injury. This degeneration occurs both in the part of the nerve that is distal to the injury and in the part that is proximal to the first node of Ranvier. As the degenerated axonal fragments are removed by phagocytosis, empty spaces are left in the neurilemmal sheath where the axons used to be.
After a few days, axons from the proximal part of the nerve start to regrow. If they are able to make contact with the distal neurilemmal sheath, they can regrow at a rate of about 1 mm per day. However, if there is any trauma, fracture, infection, or separation of the neurilemmal sheath ends that prevents contact between the axons, the regrowth can be erratic and may result in the formation of a traumatic neuroma.
In cases where the nerve injury is accompanied by significant soft tissue damage and bleeding (which increases the risk of infection), some surgeons may choose to delay the reattachment of the severed nerve ends for several weeks.
Nerve injuries can be classified into three types: neuropraxia, axonotmesis, and neurotmesis. Neuropraxia occurs when the nerve is intact but its electrical conduction is affected. However, full recovery is possible, and autonomic function is preserved. Wallerian degeneration, which is the degeneration of axons distal to the site of injury, does not occur. Axonotmesis, on the other hand, happens when the axon is damaged, but the myelin sheath is preserved, and the connective tissue framework is not affected. Wallerian degeneration occurs in this type of injury. Lastly, neurotmesis is the most severe type of nerve injury, where there is a disruption of the axon, myelin sheath, and surrounding connective tissue. Wallerian degeneration also occurs in this type of injury.
Wallerian degeneration typically begins 24-36 hours following the injury. Axons are excitable before degeneration occurs, and the myelin sheath degenerates and is phagocytosed by tissue macrophages. Neuronal repair may only occur physiologically where nerves are in direct contact. However, nerve regeneration may be hampered when a large defect is present, and it may not occur at all or result in the formation of a neuroma. If nerve regrowth occurs, it typically happens at a rate of 1mm per day.
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This question is part of the following fields:
- Neurological System
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