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Question 1
Incorrect
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Regarding antiemetics, which of the following statements is INCORRECT:
Your Answer: Metoclopramide acts directly on the gastrointestinal tract.
Correct Answer: Of the antiemetics, cyclizine is most commonly associated with acute dystonic reactions.
Explanation:Cyclizine acts by inhibiting histamine pathways and cholinergic pathways involved in transmission from the vestibular apparatus to the vomiting centre. Metoclopramide is a dopamine-receptor antagonist which acts both peripherally in the GI tract and centrally within the chemoreceptor trigger zone. Prochlorperazine is a dopamine-D2 receptor antagonist and acts centrally by blocking the chemoreceptor trigger zone. Metoclopramide and prochlorperazine are both commonly associated with extrapyramidal effects, such as acute dystonic reaction. Cyclizine may rarely cause extrapyramidal effects.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 2
Correct
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Which of the following statements about lithium treatment is FALSE:
Your Answer: Concomitant treatment with NSAIDs decreases serum-lithium concentration.
Explanation:Lithium levels are raised by NSAIDs because renal clearance is reduced. Lithium is a small ion (74 Daltons) with no protein or tissue binding and is therefore amenable to haemodialysis. Lithium is freely distributed throughout total body water with a volume of distribution between 0.6 to 0.9 L/kg, although the volume may be smaller in the elderly, who have less lean body mass and less total body water. Steady-state serum levels are typically reached within five days at the usual oral dose of 1200 to 1800 mg/day. The half-life for lithium is approximately 18 hours in adults and 36 hours in the elderly.Lithium is excreted almost entirely by the kidneys and is handled in a manner similar to sodium. Lithium is freely filtered but over 60 percent is then reabsorbed by the proximal tubules.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 3
Correct
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You are reviewing a patient complaining of loss of vision. Previous images shows a lesion at the optic chiasm. What type of visual field defect are you most likely to see in a lesion at the optic chiasm:
Your Answer: Bitemporal hemianopia
Explanation:A lesion at the optic chiasm will result in a bitemporal hemianopia.A lesion of the optic nerve will result in ipsilateral monocular visual loss.A lesion of the optic tract will result in a contralateral homonymous hemianopia.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 4
Correct
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A 16-year old boy is brought to the emergency room after suffering a traffic accident. Upon examination, there is noted ipsilateral loss of proprioception and vibration, ipsilateral motor loss, and contralateral loss of pain and temperature sensation. A spinal cord injury is given as a diagnosis.Which of the following is the most probable cause of this manifestation?
Your Answer: Brown-Séquard syndrome
Explanation:Brown-Sequard Hemicord Syndrome consists of ipsilateral weakness (corticospinal tract) and loss of joint position and vibratory sense (posterior column), with contralateral loss of pain and temperature sense (spinothalamic tract) one or two levels below the lesion. Segmental signs, such as radicular pain, muscle atrophy, or loss of a deep tendon reflex, are unilateral. Partial forms are more common than the fully developed syndrome.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 5
Correct
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Which of the following is NOT a typical feature of lithium toxicity:
Your Answer: Miosis
Explanation:Features of toxicity include:Increasing gastrointestinal disturbances (vomiting, diarrhoea, anorexia)Visual disturbancesPolyuria and incontinenceMuscle weakness and tremorTinnitusCNS disturbances (dizziness, confusion and drowsiness increasing to lack of coordination, restlessness, stupor)Abnormal reflexes and myoclonusHypernatraemiaWith severe overdosage (serum-lithium concentration > 2 mmol/L) seizures, cardiac arrhythmias (including sinoatrial block, bradycardia and first-degree heart block), blood pressure changes, electrolyte imbalance, circulatory failure, renal failure, coma and sudden death may occur.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 6
Correct
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A patient presents complaining of visual loss. On examination you note a contralateral homonymous hemianopia. Where is the most likely site of the lesion:
Your Answer: Optic tract
Explanation:At the optic chiasm, fibres from the medial (nasal) half of each retina crossover, forming the right and left optic tracts.The left optic tract contains fibres from the left lateral (temporal) retina and the right medial retina.The right optic tract contains fibres from the right lateral retina and the left medial retina.Each optic tract travels to its corresponding cerebral hemisphere to reach its lateral geniculate nucleus (LGN) located in the thalamus where the fibres synapse.A lesion of the optic tract will cause a contralateral homonymous hemianopia.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 7
Incorrect
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Which of the following cervical nerves is likely to be affected if your patient is complaining of elbow extension weakness and loss of sensation in her middle finger? She also has pain and tenderness in her cervical region, which is caused by a herniated disc, all after a whiplash-type injury in a car accident.
Your Answer: C6
Correct Answer: C7
Explanation:A C7 spinal nerve controls elbow extension and some finger extension. Damage to this nerve can result in a burning pain in the shoulder blade or back of the arms. The ability to extend shoulders, arms, and fingers may also be affected. Dexterity may also be compromised in the hands or fingers.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 8
Correct
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After an accidental fall, a 75-year-old patient complains of neck pain and weakness in his upper limbs. Select the condition that most likely caused the neck pain and weakness of the upper limbs of the patient.
Your Answer: Central cord syndrome
Explanation:The cervical spinal cord is the section of the spinal cord that goes through the bones of the neck. It is injured incompletely in the central cord syndrome (CCS). This will result in arm weakness more than leg weakness.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 9
Incorrect
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You proceed to administer lorazepam intravenously to a 21-year-old patient with status epilepticus. Which of the following best describes lorazepam's action?
Your Answer: Inhibits effect of NMDA
Correct Answer: Potentiates effect of GABA
Explanation:Lorazepam is a type of benzodiazepine. Benzodiazepines are gamma-aminobutyric acid (GABA) receptor agonists with sedative, hypnotic, anxiolytic, anticonvulsant, and muscle relaxant characteristics that promote inhibitory synaptic transmission across the central nervous system.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 10
Incorrect
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A 65-year-old man complains of severe vertigo, nausea, and tinnitus. Upon presenting himself to the emergency room, it was observed that he is exhibiting ataxia, right-sided loss of pain and temperature sense on the face, and left-sided sensory loss to the body. An MRI and CT scan was ordered and the results showed that he is suffering from a right-sided stroke. Branches of which of the following arteries are most likely implicated in the case?
Your Answer: Vertebral artery
Correct Answer: Basilar artery
Explanation:The lateral pontine syndrome occurs due to occlusion of perforating branches of the basilar and anterior inferior cerebellar (AICA) arteries. It is also known as Marie-Foix syndrome or Marie-Foix-Alajouanine syndrome. It is considered one of the brainstem stroke syndromes of the lateral aspect of the pons.It is characterized by ipsilateral limb ataxia, loss of pain and temperature sensation of the face, facial weakness, hearing loss, vertigo and nystagmus, hemiplegia/hemiparesis, and loss of pain and temperature sensation.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 11
Incorrect
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Carbamazepine is contraindicated in which of the following:
Your Answer: Raised intracranial pressure
Correct Answer: Atrioventricular block
Explanation:Carbamazepine is contraindicated in:- People with known hypersensitivity to carbamazepine or structurally related drugs- People with atrioventricular block (may suppress AV conduction and ventricular automaticity)- People with a history of bone marrow depression (risk of agranulocytosis and aplastic anaemia)- People with a history of acute porphyrias- People taking a monoamine oxidase inhibitor (risk of serotonin syndrome)
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 12
Correct
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In the emergency room, a 28-year-old woman complains of wobbly and slurred speech, is unable to do the heel-shin test, and has nystagmus. The following signs are most likely related to damage to which of the following areas:
Your Answer: Cerebellum
Explanation:Cerebellar injury causes delayed and disorganized motions. When walking, people with cerebellar abnormalities sway and stagger. Damage to the cerebellum can cause asynergia, the inability to judge distance and when to stop, dysmetria, the inability to perform rapid alternating movements or adiadochokinesia, movement tremors, staggering, wide-based walking or ataxic gait, a proclivity to fall, weak muscles or hypotonia, slurred speech or ataxic dysarthria, and abnormal eye movements or nystagmus.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 13
Incorrect
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The sensation produced by touching the arm with a vibrating tuning fork during a neurological examination is mediated by which of the following spinal tracts:
Your Answer: Lateral spinothalamic tract
Correct Answer: Posterior column
Explanation:Fine-touch, proprioception and vibration sensation are mediated by the posterior column-medial lemniscus pathway.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 14
Correct
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Which of the following is first-line for management of status epilepticus:
Your Answer: Intravenous lorazepam
Explanation:First-line treatment is with intravenous lorazepam if available. Intravenous diazepam is effective but it carries a high risk of thrombophlebitis so should only be used if intravenous lorazepam is not immediately available. Absorption of diazepam from intramuscular injection or from suppositories is too slow for treatment of status epilepticus. When facilities for resuscitation are not immediately available or if unable to secure immediate intravenous access, diazepam can be administered as a rectal solution or midazolam oromucosal solution can be given into the buccal cavity.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 15
Incorrect
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Which of the following is NOT a typical cerebellar sign:
Your Answer: Scanning/staccato speech
Correct Answer: Hypertonia
Explanation:Hypotonia means decreased muscle tone. It can be a condition on its own, called benign congenital hypotonia, or it can be indicative of another problem where there is progressive loss of muscle tone, such as muscular dystrophy or cerebral palsy. It is usually detected during infancy. Hypotonia is characteristic of cerebellar dysfunction.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 16
Incorrect
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Which of the following is a contraindication for aspirin?
Your Answer: Thrombophilia
Correct Answer: Children under 16 years
Explanation:Aspirin contraindications include: hypersensitivity to NSAIDs; asthma, rhinitis, and nasal polyps; and usage in children or teens.There is little evidence of allergic cross-reactivity for salicylates. However, due to similarities in chemical structure and/or pharmacologic activities, the possibility of cross-sensitivity cannot be completely ruled out.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 17
Incorrect
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Which of the following clinical features is most suggestive of a lesion of the frontal lobe:
Your Answer: Hemispatial neglect
Correct Answer: Conjugate eye deviation towards the side of the lesion
Explanation:Conjugate eye deviation towards the side of the lesion is seen in damage to the frontal eye field of the frontal lobe. Homonymous hemianopia is typically a result of damage to the occipital lobe (or of the optic radiation passing through the parietal and temporal lobes). Auditory agnosia may been seen in a lesion of the temporal lobe. Hemispatial neglect may be seen in a lesion of the parietal lobe. Receptive dysphasia is seen in damage to Wernicke’s area, in the temporal lobe.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 18
Correct
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Which of the following best describes the mechanism of action of aspirin:
Your Answer: Cyclo-oxygenase (COX) inhibitor
Explanation:Aspirin is a non-steroidal anti-inflammatory drug (NSAID). Aspirin irreversibly inhibits cyclooxygenase (COX) enzymes and the resulting inhibition of prostaglandin synthesis results in analgesic, antipyretic and to a lesser extent anti-inflammatory actions.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 19
Correct
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What type of visual field defect are you most likely to see in a lesion of the parietal optic radiation:
Your Answer: Contralateral homonymous inferior quadrantanopia
Explanation:A lesion of the parietal optic radiation will result in a contralateral homonymous inferior quadrantanopia.A lesion of the temporal optic radiation will result in a contralateral homonymous superior quadrantanopia.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 20
Correct
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At which opioid receptors do opioid analgesics act primarily?
Your Answer: Mu
Explanation:Opioid receptors are widely distributed throughout the central nervous system. Opioid analgesics mimic endogenous opioid peptides by causing prolonged activation of these receptors, mainly the mu(μ)-receptors which are the most highly concentrated in brain areas involved in nociception.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 21
Correct
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Question 22
Incorrect
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A 29-year-old man has been complaining about his recent headaches. Detailed history was taken and a neurological examination was performed.Which of the following cranial nerves is correctly paired with its lesion?
Your Answer: The trochlear nerve: the eye appears to look ‘down and out’
Correct Answer: The oculomotor nerve: the eye appears to look ‘down and out’
Explanation:The following are the lesions of the cranial nerves:1. Olfactory nerve (I)Reduced taste and smell, but not to ammonia which stimulates the pain fibres carried in the trigeminal nerve2. Optic nerve (II)Manifested by visual field defects, pupillary abnormalities, optic neuritis, optic atrophy, papilledema3. Oculomotor nerve (III)A fixed, dilated pupil which doesn’t accommodate, ptosis, complete internal ophthalmoplegia (masked by ptosis), unopposed lateral rectus causes outward deviation of the eye. If the ocular sympathetic fibres are also affected behind the orbit, the pupil will be fixed but not dilated.4. Trochlear nerve (IV)Diplopia due to weakness of downward and inward eye movement. The most common cause of a pure vertical diplopia. The patient tends to compensate by tilting the head away from the affected side.5. Trigeminal nerve (V)Reduced sensation or dysesthesia over the affected area. Weakness of jaw clenching and side-to-side movement. If there is a lower motor neuron (LMN) lesion, the jaw deviates to the weak side when the mouth is opened. There may be fasciculation of temporalis and masseter.6. Abducens nerve (VI)Inability to look laterally. The eye is deviated medially because of unopposed action of the medial rectus muscle.7. Facial nerve (VII)Facial weakness. In an LMN lesion the forehead is paralysed – the final common pathway to the muscles is destroyed; whereas the upper facial muscles are partially spared in an upper motor neurone (UMN) lesion because of alternative pathways in the brainstem. There appear to be different pathways for voluntary and emotional movement. CVAs usually weaken voluntary movement, often sparing involuntary movements (e.g., spontaneous smiling). The much rarer selective loss of emotional movement is called mimic paralysis and is usually due to a frontal or thalamic lesion.8. Vestibulocochlear nerve (VIII)Unilateral sensorineural deafness, tinnitus. Slow-growing lesions seldom present with vestibular symptoms as compensation has time to occur.9. Glossopharyngeal nerve (IX)Unilateral lesions do not cause any deficit because of bilateral corticobulbar connections. Bilateral lesions result in pseudobulbar palsy. These nerves are closely interlinked.10. Vagus nerve (X)Palatal weakness can cause ‘nasal speech’ and nasal regurgitation of food. The palate moves asymmetrically when the patient says ‘ahh’. Recurrent nerve palsy results in hoarseness, loss of volume and ‘bovine cough’.11. Accessory nerve (XI)Weakness and wasting of sternocleidomastoid and trapezius muscles12.Hypoglossal nerve (XII)An LMN lesion produces wasting of the ipsilateral side of the tongue, with fasciculation; and on attempted protrusion the tongue deviates towards the affected side, but the tongue deviates away from the side of a central lesion.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 23
Correct
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Which of these drugs may reduce the efficacy of contraception?
Your Answer: Carbamazepine
Explanation:Antiepileptic medications such as carbamazepine (Tegretol), topiramate (Topamax), and phenytoin (Dilantin) are widely known for reducing the contraceptive effectiveness of OCPs.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 24
Correct
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A 76-year-old man presents with complaints of double vision. Upon physical examination, it was observed that he exhibits left-sided hemiplegia and left-sided loss of joint position sense, vibratory sense and discriminatory touch. In addition, he has the inability to abduct his right eye and is holding his head towards the right side. A CT scan was ordered and showed that he has suffered a right-sided stroke. Branches of which of the following arteries are most likely implicated in the case?
Your Answer: Basilar artery
Explanation:Inferior medial pontine syndrome, also known as Foville syndrome, is one of the brainstem stroke syndromes which occurs when there is infarction of the medial inferior aspect of the pons due to occlusion of the paramedian branches of the basilar artery.It is characterized by ipsilateral sixth nerve palsy, facial palsy, contralateral hemiparesis, contralateral loss of proprioception and vibration, ipsilateral ataxia, ipsilateral facial weakness, and lateral gaze paralysis and diplopia.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 25
Incorrect
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Regarding aspirin at analgesic doses, which of the following statements is CORRECT:
Your Answer: As an analgesic, it has duration of action about 12 hours.
Correct Answer: It is contraindicated in patients with severe heart failure.
Explanation:Aspirin (at analgesic doses) is contraindicated in severe heart failure. Aspirin irreversibly inhibits cyclooxygenase (COX) enzymes resulting in decreased production of prostaglandins (which can lead to irritation of the gastric mucosa). The analgesic dose is greater than the antiplatelet dose, and taken orally it has a duration of action of about 4 hours. Clinical features of salicylate toxicity in overdose include hyperventilation, tinnitus, deafness, vasodilatation, and sweating.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 26
Incorrect
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A 70-year-old man presents with right-sided hemiplegia and loss of joint position sense, vibratory sense, and discriminatory touch. Upon further physical examination, it was observed that her tongue deviates to the left-hand side. An MRI and CT scan was ordered and results showed that he was suffering a left-sided stroke. Branches of which of the following arteries are most likely implicated in the case?
Your Answer: Superior cerebellar artery
Correct Answer: Anterior spinal artery
Explanation:Medial medullary syndrome is a form of stroke that affects the medial medulla of the brain. It is caused by a lesion in the medial part of the medulla, which is due to an infraction of vertebral arteries and/or paramedian branches of the anterior spinal artery.It is characterized by contralateral paralysis of the upper and lower limb of the body, a contralateral decrease in proprioception, vibration, and/or fine touch sensation, paresthesias or less commonly dysesthesias in the contralateral trunk and lower limb, and loss of position and vibration sense with proprioceptive dysfunction. Ipsilateral deviation of the tongue due to ipsilateral hypoglossal nerve damage can also be seen.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 27
Incorrect
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Which of the following clinical features is most suggestive of a lesion of the occipital lobe:
Your Answer: Conjugate eye deviation
Correct Answer: Homonymous hemianopia
Explanation:Homonymous hemianopia is a visual field defect involving either the two right or the two left halves of the visual fields of both eyes. It is caused by lesions of the retrochiasmal visual pathways, ie, lesions of the optic tract, the lateral geniculate nucleus, the optic radiations, and the cerebral visual (occipital) cortex
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 28
Incorrect
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The least likely feature expected to be seen in a lesion of the frontal lobe is which of the following?
Your Answer: Conjugate eye deviation towards side of lesion
Correct Answer: Loss of two-point discrimination
Explanation:Lesions in different areas give rise to different symptoms. Lesions of the parietal lobe give rise to loss of two-point discrimination. Lesions to Broca’s area give rise to expressive dysphasia results from damage Lesions to the primary motor cortex give rise to contralateral weakness of the face and arm. Lesions to the prefrontal cortex give rise to personality change. Lesions to the frontal eye field give rise to conjugate eye deviation towards side of lesion.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 29
Correct
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Which of the following is NOT a typical side effect of opioid analgesics:
Your Answer: Diarrhoea
Explanation:All opioids have the potential to cause:Gastrointestinal effects – Nausea, vomiting, constipation, difficulty with micturition (urinary retention), biliary spasmCentral nervous system effects – Sedation, euphoria, respiratory depression, miosisCardiovascular effects – Peripheral vasodilation, postural hypotensionDependence and tolerance
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 30
Incorrect
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Which of the following is NOT an adverse effect of amitriptyline:
Your Answer: Hepatic impairment
Correct Answer: Hypokalaemia
Explanation:Adverse effects include:Antimuscarinic effects: Dry mouth, Blurred vision, Constipation, Urinary retention, Sedation, ConfusionCardiovascular effects: Heart block, Arrhythmias, Tachycardia, Postural hypotension, QT-interval prolongation, Hepatic impairment, Narrow-angle glaucoma
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 31
Correct
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Which of these is NOT a lithium side effect:
Your Answer: Peptic ulcer disease
Explanation:Adverse Effects of lithium IncludeLeucocytosis (most patients)Polyuria/polydipsia (30-50%)Dry mouth (20-50%)Hand tremor (45% initially, 10% after 1 year of treatment)Confusion (40%)Decreased memory (40%)Headache (40%)Muscle weakness (30% initially, 1% after 1 year of treatment)Electrocardiographic (ECG) changes (20-30%)Nausea, vomiting, diarrhoea (10-30% initially, 1-10% after 1-2 years of treatment)Hyperreflexia (15%)Muscle twitch (15%)Vertigo (15%)Extrapyramidal symptoms, goitre (5%)Hypothyroidism (1-4%)Acne (1%)Hair thinning (1%)
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 32
Correct
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Regarding paracetamol, which of the following statements is CORRECT:
Your Answer: It has anti-pyretic action.
Explanation:Paracetamol is a non-opioid analgesic, similar in efficacy to aspirin, with antipyretic properties but no anti-inflammatory properties. It is well absorbed orally and does not cause gastric irritation. Paracetamol is a suitable first-line choice for most people with mild-to-moderate pain, and for combination therapy.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 33
Correct
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Which of the following is an adverse effect of carbamazepine:
Your Answer: Aplastic anaemia
Explanation:Common adverse effects include nausea and vomiting, sedation, dizziness, headache, blurred vision and ataxia. These adverse effects are dose related and are most common at the start of treatment.Other adverse effects include:Allergic skin reactions (and rarely, more serious dermatological conditions)Hyponatraemia (avoid concomitant use with diuretics)Leucopenia, thrombocytopenia and other blood disorders including aplastic anaemiaHepatic impairment
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 34
Correct
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A 55-year-old woman was complaining of headaches. On examination, the patient is found to have weakness on the left side of her body and her eyes are deviated towards the right hand side. These are signs of damage to which of the following areas?
Your Answer: Frontal lobe
Explanation:Some potential symptoms of frontal lobe damage can include loss of movement, either partial or complete, on the opposite side of the body. In the patient’s case, it is a result of motor cortex damage on the right side since her left side of the body is affected. The conjugate eye deviation symptom towards the side of the lesion is a result of damage to the frontal eye field.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 35
Incorrect
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What is the main mechanism of action of cyclizine:
Your Answer: Dopamine-D2 antagonist
Correct Answer: Histamine-H1 antagonist
Explanation:Antihistamines e.g. cyclizine, are effective against nausea and vomiting caused by many different conditions, including motion sickness and vertigo. These agents act by inhibiting histamine pathways, and cholinergic pathways involved in transmission from the vestibular apparatus to the vomiting centre. There is no evidence that any one antihistamine is superior to another but their duration of action and incidence of adverse effects differ. Adverse effects include drowsiness and antimuscarinic effects such as blurred vision, dry mouth, urinary retention, constipation and confusion.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 36
Incorrect
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A 70-year-old woman presents with right-sided loss of pain and temperature sense on the body as well as left-sided loss of pain and temperature sense on the face. She also has complaints of vertigo, nausea, and tinnitus. Further examination of her cranial nerves suggest the presence of Horner's Syndrome. An MRI and CT scan was ordered and results showed that she is suffering from a left-sided stroke. Branches of which of the following arteries are most likely implicated in the case?
Your Answer: Basilar artery
Correct Answer: Posterior inferior cerebellar artery
Explanation:Wallenberg syndrome is also known as lateral medullary syndrome and posterior inferior cerebellar artery syndrome. It is the most common posterior circulation ischemic stroke syndrome. The primary pathology of Wallenberg syndrome is occlusion of the posterior inferior cerebellar artery (PICA) or one of its branches.It is characterized by vertigo with nystagmus, nausea and vomiting, and sometimes hiccups, dysphonia, dysarthria, and dysphagia often present with ipsilateral loss of gag reflex, ipsilateral ataxia with a tendency to fall to the ipsilateral side, pain and numbness with impaired facial sensation on the face, impaired taste sensation, and impaired pain and temperature sensation in the arms and legs.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 37
Incorrect
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A 70-year old male is taken to the Emergency Room after suffering a traumatic fall while showering. Upon physical examination, the attending physician noted a hyperextended neck, 1/5 muscle strength in both upper extremities, 4/5 muscle strength in both lower extremities, and variable loss in sensation. The patient is placed in the wards for monitoring. For the next 24 hours, anuria is noted.Which of the following spinal cord injuries is the most likely diagnosis?
Your Answer: Anterior cord syndrome
Correct Answer: Central cord syndrome
Explanation:Central cord syndrome is the most common type of incomplete cord injury and almost always occurs due to a traumatic injury. It results in motor deficits that are worse in the upper extremities as compared to the lower extremities. It may also cause bladder dysfunction (retention) and variable sensory deficits below the level of injury.The majority of these patients will be older and present with symptoms after a fall with hyperextension of their neck. On examination, patients will have more significant strength impairments in the upper extremities (especially the hands) compared to the lower extremities. Patients often complain of sensory deficits below the level of injury, but this is variable. Pain and temperature sensations are typically affected, but the sensation of light touch can also be impaired. The most common sensory deficits are in a cape-like distribution across their upper back and down their posterior upper extremities. They will often have neck pain at the site of spinal cord impingement.Bladder dysfunction (most commonly urinary retention) and priapism can also be signs of upper motor neuron dysfunction. The sacral sensation is usually preserved, but the clinician should assess the rectal tone to evaluate the severity of the compression.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 38
Correct
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Which of the following is NOT a side effect of phenytoin:
Your Answer: Ototoxicity
Explanation:Adverse effects of phenytoin include:Nausea and vomitingDrowsiness, lethargy, and loss of concentrationHeadache, dizziness, tremor, nystagmus and ataxiaGum enlargement or overgrowthCoarsening of facial features, acne and hirsutismSkin rashesBlood disorders
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 39
Correct
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A 33-year-old woman demonstrates right-sided superior homonymous quadrantanopia upon visual field testing. A diagnosis of a brain tumour has been established.Which of the following anatomical points in the visual pathway has the lesion occurred?
Your Answer: Lower optic radiation
Explanation:Homonymous quadrantanopia is not a disease; it is a clinical finding that points towards a lesion of the optic radiations coursing through the temporal lobe.Homonymous superior quadrantanopia is caused by damage to the contralateral inferior parts of the posterior visual pathway: the inferior optic radiation (temporal Meyer loop), or the inferior part of the occipital visual cortex below the calcarine fissure.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 40
Correct
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What type of visual field defect are you likely to see in a lesion of the visual cortex:
Your Answer: Contralateral homonymous hemianopia with macular sparing
Explanation:A lesion of the visual cortex will result in a contralateral homonymous hemianopia with macular sparing.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 41
Incorrect
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Regarding codeine, which of the following statements is INCORRECT:
Your Answer: Codeine 240 mg is approximately equivalent to 30 mg of morphine.
Correct Answer: There is a reduced risk of toxicity in patients who are ultra-rapid metabolisers of codeine.
Explanation:Codeine phosphate is a weak opioid and can be used for the relief of mild to moderate pain where other painkillers such as paracetamol or ibuprofen have proved ineffective.Codeine is metabolised to morphine which is responsible for its therapeutic effects. Codeine 240 mg is approximately equivalent to 30 mg of morphine. The capacity to metabolise codeine can vary considerably between individuals; there is a marked increase in morphine toxicity in people who are ultra rapid metabolisers, and reduced therapeutic effect in poor codeine metabolisers. Codeine is contraindicated in patients of any age who are known to be ultra-rapid metabolisers of codeine (CYP2D6 ultra-rapid metabolisers).Codeine is also contraindicated in children under 12, and in children of any age who undergo the removal of tonsils or adenoids for the treatment of obstructive sleep apnoea due to reports of morphine toxicity.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 42
Incorrect
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Which of the following is most likely to cause a homonymous hemianopia:
Your Answer: Optic neuritis
Correct Answer: Posterior cerebral artery stroke
Explanation:A posterior cerebral stroke will most likely result in a contralateral homonymous hemianopia with macular sparing.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 43
Correct
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Which of the following is NOT a contraindication to treatment with aspirin at analgesic doses:
Your Answer: Myasthenia gravis
Explanation:Aspirin (at analgesic doses) is contraindicated in:People with a history of true hypersensitivity to aspirin or salicylates (symptoms of hypersensitivity to aspirin or salicylates include bronchospasm, urticaria, angioedema, and vasomotor rhinitis)People with active or previous peptic ulcerationPeople with haemophilia or another bleeding disorderChildren younger than 16 years of age (risk of Reye’s syndrome)People with severe cardiac failurePeople with severe hepatic impairmentPeople with severe renal impairmentN.B. Owing to an association with Reye’s syndrome, aspirin-containing preparations should not be given to children under 16 years, unless specifically indicated, e.g. for Kawasaki disease.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 44
Incorrect
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Regarding cortical areas, which one is found in the posterior part of the inferior frontal gyrus?
Your Answer: Secondary auditory area
Correct Answer: Broca’s area
Explanation:Broca’s area is involved in the expressive aspects of spoken and written language (production of sentences constrained by the rules of grammar and syntax). It corresponds to the opercular and triangular parts of the inferior frontal gyrus (BA 44 and 45). These areas are defined by two rami (branches) of the lateral sulcus (one ascending, one horizontal) which ‘slice into’ the inferior frontal gyrus. In keeping with its role in speech and language, Broca’s area is immediately anterior to the motor and premotor representations of the face, tongue and larynx. A homologous area in the opposite hemisphere is involved in non-verbal communication such as facial expression, gesticulation and modulation of the rate, rhythm and intonation of speech.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 45
Incorrect
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A patient diagnosed with cranial nerve palsy exhibits asymmetrical movement of the palate, nasal regurgitation of food, and nasal quality to the voice. Which of the following cranial nerves is most likely responsible for the aforementioned features?
Your Answer: Hypoglossal nerve
Correct Answer: Vagus nerve
Explanation:The vagus nerve, ‘the wanderer’, contains motor fibres (to the palate and vocal cords), sensory components (posterior and floor of external acoustic meatus) and visceral afferent and efferent fibres. Palatal weakness can cause nasal speech and nasal regurgitation of food. The palate moves asymmetrically when the patient says ‘ahh’. Recurrent nerve palsy results in hoarseness, loss of volume and ‘bovine cough’.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 46
Correct
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If a lesion is observed in Broca's area, which function is expected to become affected?
Your Answer: Formation of words
Explanation:The primary functions of the Broca area are both language production and comprehension. While the exact role in the production is still unclear, many believe that it directly impacts the motor movements to allow for speech. Although originally thought to only aid in speech production, lesions in the area can rarely be related to impairments in the comprehension of language. Different regions of the Broca area specialize in various aspects of comprehension. The anterior portion helps with semantics, or word meaning, while the posterior is associated with phonology, or how words sound. The Broca area is also necessary for language repetition, gesture production, sentence grammar and fluidity, and the interpretation of others’ actions.Broca’s aphasia is a non-fluent aphasia in which the output of spontaneous speech is markedly diminished and there is a loss of normal grammatical structure. Specifically, small linking words, conjunctions, such as and, or, and but, and the use of prepositions are lost. Patients may exhibit interjectional speech where there is a long latency, and the words that are expressed are produced as if under pressure. The ability to repeat phrases is also impaired in patients with Broca’s aphasia. Despite these impairments, the words that are produced are often intelligible and contextually correct. In pure Broca’s aphasia, comprehension is intact.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 47
Incorrect
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You suspect that your patient with polycystic kidney disease has developed a berry aneurysm as a complication of his disease. The patient complains of a sudden, severe headache. You are guessing subarachnoid haemorrhage secondary to a ruptured berry aneurysm as the cause of his severe headaches. What is the most likely location of his aneurysm?
Your Answer: Posterior communicating artery
Correct Answer: Anterior communicating artery
Explanation:One of the complications that polycystic kidney disease may cause is the development of a brain aneurysm. A berry aneurysm is the most common type of brain aneurysm. The Circle of Willis, where the major blood vessels meet at the base of the brain, is where it usually appears. The most common junctions of the Circle of Willis where an aneurysm may occur include the anterior communicating artery (35%), internal carotid artery (30%), the posterior communicating artery and the middle cerebral artery (22%), and finally, the posterior circulation sites, most commonly the basilar artery tip.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 48
Correct
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Which of the following classes of drugs may predispose to lithium toxicity:
Your Answer: Thiazide diuretics
Explanation:Excretion of lithium may be reduced by thiazide diuretics, NSAIDs, and ACE inhibitors thus predisposing to lithium toxicity. Loop diuretics also cause lithium retention but are less likely to result in lithium toxicity.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 49
Correct
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Which of the following clinical features would you least expect to see in a lesion of the frontal lobe:
Your Answer: Contralateral homonymous hemianopia with macular sparing
Explanation:Contralateral homonymous hemianopia with macular sparing results from damage to the primary visual cortex of the occipital lobe. Incontinence may occur due to damage of the cortical micturition centre in the prefrontal cortex. Primitive reflexes and inability to problem solve may occur due to damage to the prefrontal cortex. Motor weakness of the contralateral limb with UMN signs may occur due to damage of the primary motor cortex.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 50
Incorrect
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Which of the following tracts must be affected if a patient presents with decreased pain and temperature sensation in both lower extremities?
Your Answer: The corticospinal tracts
Correct Answer: The lateral spinothalamic tract
Explanation:The main function of the spinothalamic tract is to carry pain and temperature via the lateral part of the pathway and crude touch via the anterior part. The spinothalamic tract pathway is an imperative sensory pathway in human survival because it enables one to move away from noxious stimuli by carrying pain and temperature information from the skin to the thalamus where it is processed and transmitted to the primary sensory cortex. The primary sensory cortex communicates with the primary motor cortex, which lies close to it, to generate rapid movement in response to potentially harmful stimuli. Furthermore, the spinothalamic tract has a role in responding to pruritogens, causing us to itch. Interestingly, itching suppresses the spinothalamic tract neuron response to the histamine effect.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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SESSION STATS - PERFORMANCE PER SPECIALTY
