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Question 1
Correct
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A 7-year old boy is referred to the Paediatrics Department due to slurred speech. Upon further examination, the attending physician noted the presence of dysdiadochokinesia, intention tremors, and nystagmus. An MRI is taken, which revealed a brain tumour.
Which of the following options is the most probable diagnosis given the clinical features of the patient?Your Answer: Astrocytoma of cerebellum
Explanation:Pilocytic astrocytoma (PCA), previously known as cystic cerebellar astrocytoma or juvenile pilocytic astrocytoma, was first described in 1931 by Harvey Cushing, based on a case series of cerebellar astrocytomas; though he never used these terms but rather described a spongioblastoma. They are low-grade, and usually well-circumscribed tumours, which tend to occur in young patients. By the World Health Organization (WHO) classification of central nervous system tumours, they are considered grade I gliomas and have a good prognosis.
PCA most commonly occurs in the cerebellum but can also occur in the optic pathway, hypothalamus, and brainstem. They can also occur in the cerebral hemispheres, although this tends to be the case in young adults. Presentation and treatment vary for PCA in other locations. Glial cells include astrocytes, oligodendrocytes, ependymal cells, and microglia. Astrocytic tumours arise from astrocytes and are the most common tumour of glial origin. The WHO 2016 categorized these tumours as either diffuse gliomas or other astrocytic tumours. Diffuse gliomas include grade II and III diffuse astrocytomas, grade IV glioblastoma, and diffuse gliomas of childhood. The other astrocytic tumours group include PCA, pleomorphic xanthoastrocytoma, subependymal giant cell astrocytoma, and anaplastic pleomorphic xanthoastrocytoma.
PCA can present with symptoms secondary to the posterior fossa mass effect. This may include obstructive hydrocephalus, with resultant headache, nausea and vomiting, and papilledema. If hydrocephalus occurs before the fusion of the cranial sutures (<18-months-of-age), then an increase in head circumference will likely occur. Lesions of the cerebellar hemisphere result in peripheral ataxia, dysmetria, intention tremor, nystagmus, and dysarthria. In contrast, lesions of the vermis cause a broad-based gait, truncal ataxia, and titubation. Posterior fossa lesions can also cause cranial nerve palsies. Diplopia may occur due to abducens palsy from the stretching of the nerve. They may also have blurred vision due to papilledema. Seizures are rare with posterior fossa lesions.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 2
Correct
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Which of the following is NOT a typical cerebellar sign:
Your 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 3
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 4
Incorrect
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After what time period should intravenous phenytoin be used as second-line treatment of status epilepticus?
Your Answer: 30 minutes
Correct Answer: 25 minutes
Explanation:If seizures recur or fail to respond after initial treatment with benzodiazepines within 25 minutes of onset, phenytoin sodium, fosphenytoin sodium, or phenobarbital sodium should be used.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 5
Incorrect
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Regarding aspirin at analgesic doses, which of the following statements is CORRECT:
Your Answer: The increased production of prostaglandins can irritate gastric mucosa.
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 6
Incorrect
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Carbamazepine is indicated for all of the following EXCEPT for:
Your Answer: Complex focal seizures
Correct Answer: Myoclonic seizures
Explanation:Carbamazepine is a drug of choice for simple and complex focal seizures and is a first-line treatment option for generalised tonic-clonic seizures. It is also used in trigeminal neuralgia and diabetic neuropathy. Carbamazepine may exacerbate tonic, atonic, myoclonic and absence seizures and is therefore not recommended if these seizures are present.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 7
Incorrect
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Which of the following clinical features is most suggestive of a lesion of the temporal lobe:
Your Answer: Hemispatial neglect
Correct Answer: Receptive dysphasia
Explanation:Damage to the Wernicke’s speech area in the temporal lobe can result in a receptive dysphasia. Hemispatial neglect is most likely to occur in a lesion of the parietal lobe. Homonymous hemianopia is most likely to occur in a lesion of the occipital lobe. Expressive dysphasia is most likely to occur in a lesion of the Broca speech area in the frontal lobe. Conjugate eye deviation towards the side of the lesion is most likely to occur in a lesion of the frontal lobe.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 8
Incorrect
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All of the following predisposes to lithium toxicity in patients taking long-term therapy EXCEPT:
Your Answer: Co-administration of NSAIDs
Correct Answer: Hypernatraemia
Explanation:A common complication of long term lithium therapy results in most cases of lithium intoxication. It is caused by reduced excretion of the drug which can be due to several factors including deterioration of renal function, dehydration, hyponatraemia, infections, and co-administration of diuretics or NSAIDs or other drugs that may interact.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 9
Incorrect
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In a patient with an ongoing seizure, after what time period should treatment be commenced?
Your Answer: 30 seconds
Correct Answer: 5 minutes
Explanation:Immediate emergency care and treatment should be given to children, young people and adults who have prolonged or repeated convulsive seizures.
Prolonged seizures last 5 minutes or more.
Repeated seizures refer to 3 or more seizures in an hour. -
This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 10
Incorrect
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Regarding cortical areas, which one is found in the posterior part of the inferior frontal gyrus?
Your Answer: Secondary visual 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 11
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.
Which of the following is considered the best diagnosis for the case presented above?Your Answer: Lateral pontine syndrome
Correct Answer: Medial medullary syndrome
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 12
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 vomiting
Drowsiness, lethargy, and loss of concentration
Headache, dizziness, tremor, nystagmus and ataxia
Gum enlargement or overgrowth
Coarsening of facial features, acne and hirsutism
Skin rashes
Blood disorders -
This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 13
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: Posterior inferior cerebellar 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 14
Incorrect
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Regarding codeine, which of the following statements is INCORRECT:
Your Answer: Codeine phosphate is a weak opioid and can be used for the relief of mild to moderate pain.
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 15
Incorrect
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Regarding CSF (cerebrospinal fluid) production, approximately how much is produced per day?
Your Answer: 50 ml
Correct Answer: 500 ml
Explanation:CSF fills the ventricular system, a series of interconnected spaces within the brain, and the subarachnoid space directly surrounding the brain. The intraventricular CSF reflects the composition of the brain’s extracellular space via free exchange across the ependyma, and the brain “floats” in the subarachnoid CSF to minimize the effect of external mechanical forces. The volume of CSF within the cerebral ventricles is approximately 30 mL, and that in the subarachnoid space is about 125 mL. Because about 0.35 mL of CSF is produced each minute, CSF is turned over more than three times daily. Approximately 500 mL of CSF is produced per day, at a rate of about 25 mL per hour.
CSF is a filtrate of capillary blood formed largely by the choroid plexuses, which comprise pia mater, invaginating capillaries, and ependymal cells specialized for transport. The choroid plexuses are located in the lateral, third, and fourth ventricles. The lateral ventricles are situated within the two cerebral hemispheres. They each connect with the third ventricle through one of the interventricular foramina (of Monro). The third ventricle lies in the midline between the diencephalon on the two sides. The cerebral aqueduct (of Sylvius) traverses the midbrain and connects the third ventricle with the fourth ventricle. The fourth ventricle is a space defined by the pons and medulla below and the cerebellum above. The central canal of the spinal cord continues caudally from the fourth ventricle, although in adult humans the canal is not fully patent and continues to close with age.
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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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The least likely feature expected to be seen in a lesion of the frontal lobe is which of the following?
Your Answer: Expressive dysphasia
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. -
This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 17
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. -
This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 18
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 19
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 disturbances
Polyuria and incontinence
Muscle weakness and tremor
Tinnitus
CNS disturbances (dizziness, confusion and drowsiness increasing to lack of coordination, restlessness, stupor)
Abnormal reflexes and myoclonus
Hypernatraemia
With 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. -
This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 20
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 21
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. -
This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 22
Incorrect
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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: Anterior cord syndrome
Correct 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 23
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 24
Correct
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A 34-year-old man presents with loss of vision in his left eye due to an episode of optic neuritis. Upon history taking, it was noted that he has a history of multiple sclerosis.
Which of the following anatomical points in the visual pathway has the lesion occurred?Your Answer: Optic nerve
Explanation:A lesion in the optic nerve causes ipsilateral monocular visual loss.
Optic neuritis is an inflammatory demyelination of the optic nerve that is highly associated with multiple sclerosis. The two most common symptoms of optic neuritis are vision loss and eye pain. -
This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 25
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: Vertebral 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 26
Incorrect
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What is the main mechanism of action of metoclopramide:
Your Answer: Serotonin-5HT3 antagonist
Correct Answer: Dopamine antagonist
Explanation:Metoclopramide is a dopamine-receptor antagonist. Blockade of inhibitory dopamine receptors in the GI tract may allow stimulatory actions of ACh at muscarinic synapses to predominate. Metoclopramide also blocks dopamine D2-receptors within the chemoreceptor trigger zone (CTZ). At high doses, it is also thought to have some 5-HT3antagonist activity.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 27
Correct
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Which of these is NOT a lithium side effect:
Your Answer: Peptic ulcer disease
Explanation:Adverse Effects of lithium Include
Leucocytosis (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%) -
This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 28
Correct
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What is the main mechanism of action of cyclizine:
Your 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 29
Correct
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Question 30
Incorrect
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A patient complains of headache and visual loss. CT scan demonstrates a lesion of the temporal lobe. What type of visual field defect would you most expect to see in this patient:
Your Answer: Contralateral homonymous hemianopia
Correct Answer: Contralateral homonymous superior quadrantanopia
Explanation:Axons from the lateral geniculate nucleus (LGN) carry visual information, via the upper and lower optic radiations, to the visual cortex in the occipital lobe:
The upper optic radiation carries fibres from the superior retinal quadrants (corresponding to the inferior visual field quadrants) and travels through the parietal lobe to reach the visual cortex.
The lower optic radiation carries fibres from the inferior retinal quadrants (corresponding to the superior visual field quadrants) and travels through the temporal lobe to reach the visual cortex of the occipital lobe. -
This question is part of the following fields:
- Anatomy
- Central Nervous System
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SESSION STATS - PERFORMANCE PER SPECIALTY
