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  • Question 1 - A 35-year-old female patient with a history of relapsing-remitting multiple sclerosis presents with...

    Incorrect

    • A 35-year-old female patient with a history of relapsing-remitting multiple sclerosis presents with new-onset double vision. She reports that in the last week, she has noticed double vision when trying to focus on objects on the left side of her visual field. She reports no double vision when looking to the right.

      During examination, asking the patient to track the examiner's finger and look to the left (i.e. left horizontal conjugate gaze) elicits double vision, with the patient reporting that images appear 'side by side.' Additionally, there is a failure of the right eye to adduct past the midline, and nystagmus is noted in the left eye. Asking the patient to look to the right elicits no symptoms or abnormal findings. Asking the patient to converge her eyes on a nearby, midline object elicits no abnormalities, and the patient can abduct both eyes.

      Which part of the nervous system is most likely responsible for this patient's symptoms?

      Your Answer: Nucleus of the oculomotor nerve

      Correct Answer: Paramedian area of midbrain and pons

      Explanation:

      The medial longitudinal fasciculus is a pathway located in the paramedian area of the midbrain and pons that coordinates horizontal conjugate gaze by connecting the abducens nerve nucleus (CN VI) with the contralateral oculomotor nerve nucleus (CN III). Lesions in the MLF can result in internuclear ophthalmoplegia (INO), which is commonly caused by demyelinating disorders like multiple sclerosis. Bilateral INO is often associated with multiple sclerosis.

      The other options listed in the vignette can also cause visual disturbances, but they are not the cause of the patient’s INO. Lesions in the occipital lobe can cause contralateral homonymous, macular-sparing quadrantanopia or hemianopia. Lateral medullary lesions (Wallenberg syndrome) can cause an ipsilateral Horner’s syndrome marked by ptosis, miosis, and anhidrosis. Optic neuritis, which is common in multiple sclerosis, can cause blurred vision, colour desaturation, and eye pain, but it would not result in binocular diplopia that improves on covering the unaffected eye. Lesions affecting the oculomotor nerve nucleus would also affect the ipsilateral eye’s ability to abduct on horizontal conjugate gaze, but the test of convergence can help distinguish this from an MLF lesion.

      Understanding Internuclear Ophthalmoplegia

      Internuclear ophthalmoplegia is a condition that affects the horizontal movement of the eyes. It is caused by a lesion in the medial longitudinal fasciculus (MLF), which is responsible for interconnecting the IIIrd, IVth, and VIth cranial nuclei. This area is located in the paramedian region of the midbrain and pons. The main feature of this condition is impaired adduction of the eye on the same side as the lesion, along with horizontal nystagmus of the abducting eye on the opposite side.

      The most common causes of internuclear ophthalmoplegia are multiple sclerosis and vascular disease. It is important to note that this condition can also be a sign of other underlying neurological disorders.

    • This question is part of the following fields:

      • Neurological System
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  • Question 2 - A 72-year-old woman arrives at the emergency department with confused speech and weakness...

    Correct

    • A 72-year-old woman arrives at the emergency department with confused speech and weakness on the right side. During the examination, you observe weakness in the right upper limb, but no sensory loss. The patient appears perplexed when answering questions, and her speech is incoherent and nonsensical. What region of the brain is responsible for receptive dysphasia?

      Your Answer: Wernicke's area

      Explanation:

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 3 - A teenage boy is undergoing a procedure to remove an abscess on his...

    Correct

    • A teenage boy is undergoing a procedure to remove an abscess on his back. While being put under general anesthesia, he is administered fentanyl intravenously for pain relief.

      What characteristics of fentanyl make it a preferable choice in this situation over other opioids such as morphine?

      Your Answer: Fentanyl is more lipophilic and therefore has a faster onset

      Explanation:

      Fentanyl analgesic onset is faster than morphine because of its higher lipophilicity, allowing it to penetrate the CNS more rapidly.

      When inducing anesthesia, it is crucial to have a quick-acting analgesic to minimize the physical response to intubation. Fentanyl’s greater lipophilicity enables it to cross the blood-brain barrier more efficiently, resulting in a faster effect on the CNS.

      Both fentanyl and morphine bind to opioid receptors in the CNS, producing their effects.

      Due to its higher potency, fentanyl requires a smaller dosage than morphine.

      As a synthetic opioid, fentanyl causes less nausea and vomiting.

      Understanding Opioids: Types, Receptors, and Clinical Uses

      Opioids are a class of chemical compounds that act upon opioid receptors located within the central nervous system (CNS). These receptors are G-protein coupled receptors that have numerous actions throughout the body. There are three clinically relevant groups of opioid receptors: mu (µ), kappa (κ), and delta (δ) receptors. Endogenous opioids, such as endorphins, dynorphins, and enkephalins, are produced by specific cells within the CNS and their actions depend on whether µ-receptors or δ-receptors and κ-receptors are their main target.

      Drugs targeted at opioid receptors are the largest group of analgesic drugs and form the second and third steps of the WHO pain ladder of managing analgesia. The choice of which opioid drug to use depends on the patient’s needs and the clinical scenario. The first step of the pain ladder involves non-opioids such as paracetamol and non-steroidal anti-inflammatory drugs. The second step involves weak opioids such as codeine and tramadol, while the third step involves strong opioids such as morphine, oxycodone, methadone, and fentanyl.

      The strength, routes of administration, common uses, and significant side effects of these opioid drugs vary. Weak opioids have moderate analgesic effects without exposing the patient to as many serious adverse effects associated with strong opioids. Strong opioids have powerful analgesic effects but are also more liable to cause opioid-related side effects such as sedation, respiratory depression, constipation, urinary retention, and addiction. The sedative effects of opioids are also useful in anesthesia with potent drugs used as part of induction of a general anesthetic.

    • This question is part of the following fields:

      • Neurological System
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  • Question 4 - Which one of the following pairings of foramina and their contents is not...

    Incorrect

    • Which one of the following pairings of foramina and their contents is not correct?

      Your Answer: Foramina rotundum and the maxillary nerve

      Correct Answer: Jugular foramen and the hypoglossal nerve

      Explanation:

      The hypoglossal canal is the pathway for the hypoglossal nerve.

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 5 - A 10-year-old girl arrives at the emergency department with her father. She complains...

    Correct

    • A 10-year-old girl arrives at the emergency department with her father. She complains of a headache followed by seeing flashing lights and floaters. Her father also noticed her eyes moving from side to side. What type of seizure is likely to be associated with these symptoms?

      Your Answer: Occipital lobe seizure

      Explanation:

      Visual changes like floaters and flashes are common symptoms of occipital lobe seizures, while hallucinations and automatisms are associated with temporal lobe seizures. Head and leg movements, as well as postictal weakness, are typical of frontal lobe seizures, while paraesthesia is a common symptom of parietal lobe seizures.

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 6 - A 50-year-old man presents to the physician with complaints of difficulty in making...

    Correct

    • A 50-year-old man presents to the physician with complaints of difficulty in making facial expressions such as smiling and frowning. Due to a family history of brain tumours, the doctor orders an MRI scan.

      In case a tumour is detected, which foramen of the skull is likely to be the site of the tumour?

      Your Answer: Internal acoustic meatus

      Explanation:

      The correct answer is that the facial nerve passes through the internal acoustic meatus, along with the vestibulocochlear nerve. This nerve is responsible for facial expressions, which is consistent with the patient’s reported difficulties with smiling and frowning.

      The other options are incorrect because they do not match the patient’s symptoms. The mandibular nerve passes through the foramen ovale and is responsible for sensations around the jaw, but the patient does not report any problems with eating. The maxillary nerve passes through the foramen rotundum and provides sensation to the middle of the face, but the patient does not have any sensory deficits. The hypoglossal nerve passes through the hypoglossal canal and is responsible for tongue movement, but the patient does not report any difficulties with this. The glossopharyngeal, vagus, and accessory nerves pass through the jugular foramen and are responsible for various motor and sensory functions, but none of them innervate the facial muscles.

      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.

    • This question is part of the following fields:

      • Neurological System
      77.1
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  • Question 7 - A teenage boy is in a car crash and experiences a spinal cord...

    Incorrect

    • A teenage boy is in a car crash and experiences a spinal cord injury resulting in a hemisection of his spinal cord. What clinical features will he exhibit on examination below the level of injury?

      Your Answer: Weakness on the opposite side and loss of light touch sensation and pain on the same side

      Correct Answer: Weakness and loss of light touch sensation on the same side and loss of pain on the opposite side

      Explanation:

      When a hemisection of the spinal cord occurs, it results in a condition known as Brown-Sequard syndrome. This condition is characterized by sensory and motor loss on the same side of the injury, as well as pain loss on the opposite side. The loss of motor function on the same side is due to damage to the corticospinal tract, which does not cross over within the spinal cord but instead decussates in the brainstem. Similarly, the loss of light touch on the same side is due to damage to the dorsal column, which also decussates in the brainstem. In contrast, the loss of pain on the opposite side is due to damage to the spinothalamic tract, which decussates at the level of sensory input. As a result, pain signals are always carried on the opposite side of the spinal cord, while motor and light touch signals are carried on the same side as the injury.

      Understanding Brown-Sequard Syndrome

      Brown-Sequard syndrome is a condition that occurs when there is a lateral hemisection of the spinal cord. This condition is characterized by a combination of symptoms that affect the body’s ability to sense and move. Individuals with Brown-Sequard syndrome experience weakness on the same side of the body as the lesion, as well as a loss of proprioception and vibration sensation on that side. On the opposite side of the body, there is a loss of pain and temperature sensation.

      It is important to note that the severity of Brown-Sequard syndrome can vary depending on the location and extent of the spinal cord injury. Some individuals may experience only mild symptoms, while others may have more severe impairments. Treatment for Brown-Sequard syndrome typically involves a combination of physical therapy, medication, and other supportive measures to help manage symptoms and improve overall quality of life.

    • This question is part of the following fields:

      • Neurological System
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  • Question 8 - In the proximal third of the upper arm, where is the musculocutaneous nerve...

    Incorrect

    • In the proximal third of the upper arm, where is the musculocutaneous nerve situated?

      Your Answer: Between the brachialis and triceps muscles

      Correct Answer: Between the biceps brachii and brachialis muscles

      Explanation:

      The biceps and brachialis muscles are located on either side of the musculocutaneous nerve.

      The Musculocutaneous Nerve: Function and Pathway

      The musculocutaneous nerve is a nerve branch that originates from the lateral cord of the brachial plexus. Its pathway involves penetrating the coracobrachialis muscle and passing obliquely between the biceps brachii and the brachialis to the lateral side of the arm. Above the elbow, it pierces the deep fascia lateral to the tendon of the biceps brachii and continues into the forearm as the lateral cutaneous nerve of the forearm.

      The musculocutaneous nerve innervates the coracobrachialis, biceps brachii, and brachialis muscles. Injury to this nerve can cause weakness in flexion at the shoulder and elbow. Understanding the function and pathway of the musculocutaneous nerve is important in diagnosing and treating injuries or conditions that affect this nerve.

    • This question is part of the following fields:

      • Neurological System
      42.7
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  • Question 9 - A 27-year-old male patient visits his doctor complaining of right eye discomfort and...

    Incorrect

    • A 27-year-old male patient visits his doctor complaining of right eye discomfort and a feeling of having a foreign object in it. He mentions that the symptoms have been getting worse for the past 3 days after he went to a concert. He wears contact lenses and did not remove them for several days during the event, opting to wash his eyes with water instead.

      What could be the probable reason for his visit?

      Your Answer: Chlamydia trachomatis conjunctivitis

      Correct Answer: Acanthamoeba infection

      Explanation:

      Wearing contact lenses increases the risk of acanthamoeba infection, which can cause keratitis. Symptoms include severe pain, haloes around lights, and blurred vision. Acute angle closure glaucoma may also cause eye pain, but the history of contact lens use makes acanthamoeba infection more likely. Temporal arteritis, chlamydial conjunctivitis, and thyroid eye disease have different symptoms and are less likely to be the cause of eye pain in this case.

      Understanding Keratitis: Inflammation of the Cornea

      Keratitis is a condition that refers to the inflammation of the cornea, which is the clear, dome-shaped surface that covers the front of the eye. While there are various causes of keratitis, microbial keratitis is a particularly serious form of the condition that can lead to vision loss if left untreated. Bacterial keratitis is often caused by Staphylococcus aureus, while Pseudomonas aeruginosa is commonly seen in contact lens wearers. Fungal and amoebic keratitis are also possible, with acanthamoebic keratitis accounting for around 5% of cases. Other factors that can cause keratitis include viral infections, environmental factors like photokeratitis, and contact lens-related issues like contact lens acute red eye (CLARE).

      Symptoms of keratitis typically include a painful, red eye, photophobia, and a gritty sensation or feeling of a foreign body in the eye. In some cases, hypopyon may be seen. If a person is a contact lens wearer and presents with a painful red eye, an accurate diagnosis can only be made with a slit-lamp, meaning same-day referral to an eye specialist is usually required to rule out microbial keratitis.

      Management of keratitis typically involves stopping the use of contact lenses until symptoms have fully resolved, as well as the use of topical antibiotics like quinolones and cycloplegic agents for pain relief. Complications of keratitis can include corneal scarring, perforation, endophthalmitis, and visual loss. It is important to seek urgent evaluation and treatment for microbial keratitis to prevent these potential complications.

    • This question is part of the following fields:

      • Neurological System
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  • Question 10 - What are the true statements about the musculocutaneous nerve, except for those that...

    Incorrect

    • What are the true statements about the musculocutaneous nerve, except for those that are false?

      Your Answer: It runs beneath biceps

      Correct Answer: If damaged, then extension of the elbow joint will be impaired

      Explanation:

      The muscles supplied by it include the biceps, brachialis, and coracobrachialis. If it is injured, the ability to flex the elbow may be affected.

      The Musculocutaneous Nerve: Function and Pathway

      The musculocutaneous nerve is a nerve branch that originates from the lateral cord of the brachial plexus. Its pathway involves penetrating the coracobrachialis muscle and passing obliquely between the biceps brachii and the brachialis to the lateral side of the arm. Above the elbow, it pierces the deep fascia lateral to the tendon of the biceps brachii and continues into the forearm as the lateral cutaneous nerve of the forearm.

      The musculocutaneous nerve innervates the coracobrachialis, biceps brachii, and brachialis muscles. Injury to this nerve can cause weakness in flexion at the shoulder and elbow. Understanding the function and pathway of the musculocutaneous nerve is important in diagnosing and treating injuries or conditions that affect this nerve.

    • This question is part of the following fields:

      • Neurological System
      50.4
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