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Question 1
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 2
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 3
Correct
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A 70-year-old man has a resting tremor, rigidity, bradykinesia, and a shuffling gait. Parkinson's disease is caused by one of the following mechanisms:
Your Answer: Loss of dopaminergic neurons in the substantia nigra
Explanation:Parkinson’s disease (PD) is one of the most common neurologic disorders, affecting approximately 1% of individuals older than 60 years and causing progressive disability that can be slowed but not halted, by treatment. The 2 major neuropathologic findings in Parkinson’s disease are loss of pigmented dopaminergic neurons of the substantia nigra pars compacta and the presence of Lewy bodies and Lewy neurites. See the images below.
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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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What type of visual field defect are you likely to see in a lesion of the visual cortex:
Your Answer: Contralateral homonymous superior quadrantanopia
Correct 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 5
Incorrect
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Which of the following classes of drugs may predispose to lithium toxicity:
Your Answer: Theophylline
Correct 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 6
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: Anterior spinal 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 7
Incorrect
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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: Posterior cerebral artery
Correct 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 8
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 9
Incorrect
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Which of the following is a contraindication to the use of opioid analgesics:
Your Answer: Acute porphyria
Correct Answer: Raised intracranial pressure
Explanation:Opioids should be avoided in people who have: A risk of paralytic ileus (opioids reduce gastric motility)Acute respiratory depressionAn acute exacerbation of asthma (opioids can aggravate bronchoconstriction as a result of histamine release)Conditions associated with increased intracranial pressure including head injury (opioids can interfere with pupillary response making neurological assessment difficult and may cause retention of carbon dioxide aggravating the increased intracranial pressure)
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 10
Correct
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Regarding antiemetics, which of the following statements is INCORRECT:
Your 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 11
Incorrect
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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 chiasm
Correct 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.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 12
Incorrect
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Which of the following is NOT a side effect of phenytoin:
Your Answer: Acne and hirsutism
Correct 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 13
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 14
Incorrect
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A 54 year old patient presents with vertigo, ipsilateral hemiataxia, dysarthria, ptosis and miosis. Which of these blood vessels has most likely been occluded?
Your Answer: Superior cerebellar artery
Correct Answer: Posterior inferior cerebellar artery
Explanation:Posterior inferior cerebellar artery (PICA) occlusion is characterised by vertigo, ipsilateral hemiataxia, dysarthria, ptosis and miosis. PICA occlusion causes infarction of the posterior inferior cerebellum, inferior cerebellar vermis and lateral medulla.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 15
Incorrect
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Which of these drugs may reduce the efficacy of contraception?
Your Answer: Sodium valproate
Correct 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 16
Correct
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Which of the following statements is correct regarding paracetamol?
Your Answer: Liver damage peaks 3 to 4 days after paracetamol ingestion.
Explanation:The maximum daily dose of paracetamol in an adult is 4 grams. Doses greater than this can lead to hepatotoxicity and, less frequently, acute kidney injury. Early symptoms of paracetamol toxicity include nausea, vomiting, and abdominal pain, and usually settle within 24 hours. Symptoms of liver damage include right subcostal pain and tenderness, and this peaks 3 to 4 days after paracetamol ingestion. Other signs of hepatic toxicity include encephalopathy, bleeding, hypoglycaemia, and cerebral oedema.
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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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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 18
Incorrect
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Which of the following statements is true about anterior cord syndrome?
Your Answer: It has the best prognosis of the incomplete spinal cord injuries
Correct Answer: There is preservation of proprioception
Explanation:Anterior cord syndrome is an incomplete cord syndrome that predominantly affects the anterior 2/3 of the spinal cord, characteristically resulting in motor paralysis below the level of the lesion as well as the loss of pain and temperature at and below the level of the lesion. The patient presentation typically includes these two findings; however, there is variability depending on the portion of the spinal cord affected. Other findings include back pain, or autonomic dysfunction such as hypotension, neurogenic bowel or bladder, and sexual dysfunction. The severity of motor dysfunction can vary, typically resulting in paraplegia or quadriplegia.Proprioception, vibratory sense, two-point discrimination, and fine touch are not affected in anterior cord syndrome. These sensations are under the control of the dorsal column of the spinal cord, which is supplied by two posterior spinal arteries running in the posterior lateral sulci.
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This question is part of the following fields:
- Anatomy
- Central Nervous System
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Question 19
Correct
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Question 20
Incorrect
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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: Upper optic radiation
Correct 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 21
Incorrect
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Which of the following is most likely to cause a homonymous hemianopia:
Your Answer: Pituitary adenoma
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 22
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 23
Incorrect
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Which of the following best describes the mechanism of action of aspirin:
Your Answer: Increases production of prostaglandins
Correct 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 24
Correct
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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 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 25
Incorrect
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What is the main mechanism of action of cyclizine:
Your Answer: Histamine-H2 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 26
Incorrect
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Which of the following statements about lithium treatment is FALSE:
Your Answer: Lithium may lower the seizure threshold in patients with epilepsy.
Correct 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 27
Correct
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Regarding aspirin at analgesic doses, which of the following statements is CORRECT:
Your 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 28
Correct
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Which of the following is a contraindication for aspirin?
Your 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 29
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: Posterior inferior 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 30
Incorrect
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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 chiasm
Correct 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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SESSION STATS - PERFORMANCE PER SPECIALTY
