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Iraqi Board Neurology study materials
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Iraqi Board Neurology practice questions

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Question 1Neuroanatomy and Neurophysiology

A 55-year-old man has a right homonymous hemianopia with macular sparing after an occipital infarct. Which vascular territory is most likely involved?

  1. Right posterior cerebral artery
  2. Right anterior choroidal artery
  3. Left middle cerebral artery
  4. Left posterior cerebral artery Correct answer.

Explanation

The optic radiations and primary visual cortex are organized so that the left hemisphere processes the right visual field; a right homonymous hemianopia therefore localizes to the left retrochiasmal pathway. Macular sparing is characteristic of posterior cerebral artery infarction because the occipital pole receives collateral supply from the middle cerebral artery.

Question 2Neuroanatomy and Neurophysiology

Which brainstem structure contains the cell bodies of the parasympathetic fibers that innervate the pupil constrictor?

  1. Nucleus ambiguus
  2. Superior salivatory nucleus
  3. Edinger-Westphal nucleus Correct answer.
  4. Dorsal motor nucleus of the vagus

Explanation

Preganglionic parasympathetic neurons for the pupillary light reflex arise in the Edinger-Westphal nucleus, travel with the oculomotor nerve, and synapse in the ciliary ganglion. Postganglionic fibers then innervate the sphincter pupillae and ciliary muscle.

Question 3Neuroanatomy and Neurophysiology

A patient cannot abduct the right eye, and the right pupil is small with a mildly drooping eyelid. Sensation over the right forehead is reduced. Where is the lesion?

  1. Right cavernous sinus Correct answer.
  2. Right cerebellopontine angle
  3. Right midbrain
  4. Right orbital apex

Explanation

The combination of abducens palsy, Horner syndrome, and ophthalmic division sensory loss points to involvement of the abducens nerve, sympathetic plexus, and V1 within the cavernous sinus. These structures travel together in the lateral wall of the sinus.

Question 4Neuroanatomy and Neurophysiology

Which cerebellar region is primarily responsible for coordinating the distal muscles of the limbs during voluntary movement?

  1. Flocculonodular lobe
  2. Fastigial nucleus
  3. Neocerebellum (lateral hemispheres) Correct answer.
  4. Vermis

Explanation

The lateral cerebellar hemispheres, or neocerebellum, receive corticopontocerebellar input and regulate the timing and coordination of skilled distal limb movements. Lesions here produce intention tremor and limb dysmetria.

Question 5Neuroanatomy and Neurophysiology

A 40-year-old woman has progressive weakness and wasting of the small muscles of the hand, a sensory level at C8-T1, and a Horner syndrome on the same side. MRI shows a cervical cord lesion. Which syndrome best fits?

  1. Central cord syndrome
  2. Anterior cord syndrome Correct answer.
  3. Posterior cord syndrome
  4. Brown-Séquard syndrome

Explanation

Anterior spinal artery territory infarction damages the anterior horns, spinothalamic tracts, and descending sympathetic fibers, producing flaccid weakness and wasting at the level, a suspended sensory level, and ipsilateral Horner syndrome. Posterior columns are spared.

Question 6Neuroanatomy and Neurophysiology

Which ascending tract carries unconscious proprioceptive information from muscle spindles and Golgi tendon organs to the cerebellum?

  1. Medial lemniscus
  2. Dorsal spinocerebellar tract Correct answer.
  3. Ventral spinothalamic tract
  4. Lateral spinothalamic tract

Explanation

The spinocerebellar tracts convey unconscious proprioceptive data from muscle spindles, tendon organs, and joint receptors to the cerebellum for coordination of movement. The dorsal spinocerebellar tract arises from Clarke's nucleus and ascends ipsilaterally.

Question 7Neuroanatomy and Neurophysiology

A lesion of the right optic tract produces which visual field defect?

  1. Bitemporal hemianopia
  2. Left homonymous hemianopia Correct answer.
  3. Left superior quadrantanopia
  4. Right homonymous hemianopia

Explanation

The right optic tract carries fibers from the temporal retina of the right eye and the nasal retina of the left eye, both of which subserve the left visual field. Damage therefore produces a left homonymous hemianopia.

Question 8Neuroanatomy and Neurophysiology

Which neurotransmitter is released by the preganglionic neurons of the sympathetic nervous system?

  1. Acetylcholine Correct answer.
  2. Norepinephrine
  3. Epinephrine
  4. Dopamine

Explanation

All preganglionic autonomic neurons, sympathetic and parasympathetic, release acetylcholine that acts on nicotinic receptors in the ganglion. Norepinephrine is released by most postganglionic sympathetic terminals.

Question 9Neuroanatomy and Neurophysiology

A 65-year-old man develops sudden vertigo, diplopia, and crossed sensory loss with ipsilateral facial numbness and contralateral body numbness. Which structure is most likely infarcted?

  1. Medial medulla
  2. Lateral medulla Correct answer.
  3. Lateral pons
  4. Medial midbrain

Explanation

Lateral medullary infarction (Wallenberg syndrome) results from occlusion of the posterior inferior cerebellar artery or vertebral artery and produces vertigo, Horner syndrome, dysphagia, and crossed pain/temperature loss due to involvement of the spinothalamic tract and spinal trigeminal nucleus.

Question 10Neuroanatomy and Neurophysiology

Which cranial nerve nucleus provides the motor innervation to the stapedius muscle?

  1. Facial nerve nucleus Correct answer.
  2. Trigeminal motor nucleus
  3. Nucleus ambiguus
  4. Hypoglossal nucleus

Explanation

The stapedius muscle is innervated by a branch of the facial nerve, which arises from the facial motor nucleus in the pons. Its contraction dampens ossicular movement and protects the cochlea from loud sounds.

Question 11Neuroanatomy and Neurophysiology

During a nerve conduction study, a reduced amplitude of the compound muscle action potential with normal conduction velocity and normal distal latency most suggests which process?

  1. Neuromuscular junction blockade
  2. Anterior horn cell disease
  3. Axonal loss Correct answer.
  4. Demyelinating neuropathy

Explanation

Reduced CMAP amplitude with preserved conduction velocity and distal latency reflects loss of axons or muscle fibers rather than myelin damage. Demyelination characteristically slows conduction velocity and prolongs distal latency.

Question 12Neuroanatomy and Neurophysiology

Which EEG pattern is most characteristic of a normal awake adult with eyes closed?

  1. 3-Hz spike-and-wave discharges
  2. Diffuse beta activity of low voltage
  3. Burst suppression
  4. Alpha rhythm over the posterior head regions Correct answer.

Explanation

The normal awake adult resting EEG with eyes closed shows a posterior dominant alpha rhythm at 8 to 13 Hz that attenuates with eye opening. This is the hallmark of a normal background.

Question 13Neuroanatomy and Neurophysiology

A 30-year-old woman has fatigable ptosis and proximal weakness that worsens with repetitive use. Repetitive nerve stimulation shows a decrement greater than 10%. Which mechanism explains the decrement?

  1. Demyelination of the neuromuscular junction
  2. Loss of anterior horn cells
  3. Impaired acetylcholine release
  4. Antibodies against postsynaptic acetylcholine receptors Correct answer.

Explanation

Myasthenia gravis is caused by antibodies against postsynaptic acetylcholine receptors, reducing the safety factor of transmission. With repetitive stimulation, progressively fewer receptors are available, producing a decremental response.

Question 14Neuroanatomy and Neurophysiology

Which structure forms the primary output pathway from the basal ganglia to the thalamus?

  1. Globus pallidus externus and subthalamic nucleus
  2. Caudate nucleus and amygdala
  3. Striatum and putamen
  4. Globus pallidus internus and substantia nigra pars reticulata Correct answer.

Explanation

The major basal ganglia output is conveyed by inhibitory GABAergic projections from the globus pallidus internus and substantia nigra pars reticulata to the thalamus. This output modulates thalamocortical activity and movement initiation.

Question 15Neuroanatomy and Neurophysiology

A patient has a lesion of the left medial longitudinal fasciculus. What clinical finding is expected on attempted rightward gaze?

  1. Left eye fails to adduct, right eye has nystagmus
  2. Right eye fails to adduct, left eye has nystagmus Correct answer.
  3. Both eyes fail to adduct
  4. Both eyes fail to abduct

Explanation

An internuclear ophthalmoplegia from a left MLF lesion impairs adduction of the ipsilateral left eye during rightward gaze and produces abducting nystagmus of the right eye. The lesion disrupts the connection between the abducens nucleus and the contralateral oculomotor nucleus.

Question 16Neuroanatomy and Neurophysiology

Which of the following is the principal function of the thalamic reticular nucleus?

  1. Controlling autonomic outflow
  2. Generating voluntary movement
  3. Relaying sensory information to the cortex
  4. Gating and modulating thalamocortical activity Correct answer.

Explanation

The thalamic reticular nucleus is a thin shell of GABAergic neurons around the thalamus that inhibits thalamic relay cells and modulates thalamocortical transmission. It acts as a gate for sensory and arousal-related information.

Question 17Neuropathology and Basic Neuroscience

A 45-year-old man presents with a 6-month history of progressive cognitive decline and frequent falls. MRI shows ventriculomegaly, and a brain biopsy shows enlarged, pale eosinophilic neurons with loss of Nissl substance. Which cellular change is most characteristic of this condition?

  1. Lewy bodies
  2. Red neurons with pyknotic nuclei
  3. Neurofibrillary tangles
  4. Ballooned neurons with eosinophilic cytoplasm Correct answer.

Explanation

The clinical picture and histology describe Pick disease, a frontotemporal lobar degeneration, in which ballooned neurons (Pick cells) with eosinophilic cytoplasm and loss of Nissl substance are characteristic. These ballooned neurons are distinct from the ischemic red neurons and from the inclusion bodies seen in other neurodegenerative diseases.

Question 18Neuropathology and Basic Neuroscience

During a neuropathology review, a 62-year-old woman with progressive dementia is found to have abundant amyloid plaques and neurofibrillary tangles in the hippocampus and neocortex. Which molecular abnormality is most directly responsible for the formation of neurofibrillary tangles?

  1. Expansion of CAG repeats
  2. Mutation in the prion protein gene
  3. Accumulation of alpha-synuclein
  4. Hyperphosphorylation of tau protein Correct answer.

Explanation

Neurofibrillary tangles are composed of paired helical filaments of hyperphosphorylated tau, a microtubule-associated protein. This phosphorylation reduces tau's affinity for microtubules and promotes its aggregation into filaments, a hallmark of Alzheimer disease.

Question 19Neuropathology and Basic Neuroscience

A 70-year-old man with a history of hypertension and atrial fibrillation dies suddenly. Autopsy reveals a large, wedge-shaped area of softening in the territory of the middle cerebral artery. Microscopic examination shows a dense infiltrate of macrophages filled with myelin breakdown products. Which pathological stage of infarction does this represent?

  1. Subacute stage (days to weeks) Correct answer.
  2. Chronic stage (months to years)
  3. Hemorrhagic transformation
  4. Acute stage (first 12 hours)

Explanation

The subacute stage of cerebral infarction, typically occurring days to weeks after the event, is characterized by macrophage infiltration and phagocytosis of necrotic tissue and myelin breakdown products. This leads to tissue cavitation and the appearance of lipid-laden macrophages.

Question 20Neuropathology and Basic Neuroscience

A 55-year-old woman with a history of breast carcinoma presents with a 2-week history of headache and confusion. MRI shows multiple ring-enhancing lesions at the gray-white junction. A stereotactic biopsy is performed. Which histological finding would most strongly support a diagnosis of metastatic carcinoma rather than a primary brain tumor?

  1. Rosenthal fibers
  2. Pseudopalisading necrosis
  3. Perivascular pseudorosettes
  4. Glandular structures with mucin production Correct answer.

Explanation

Metastatic adenocarcinomas, such as from breast, often form glandular structures and may produce mucin, reflecting their epithelial origin. These features are not typical of primary brain tumors like glioblastoma or ependymoma.

Question 21Neuropathology and Basic Neuroscience

A 35-year-old man presents with a 3-month history of progressive weakness and sensory loss in the legs. MRI shows a longitudinally extensive spinal cord lesion. He later develops optic neuritis. Serum testing for aquaporin-4 antibodies is positive. Which pathological finding is most characteristic of this condition?

  1. Spongiform change with prion protein deposition
  2. Thickened hyalinized blood vessels with Rosenthal fibers
  3. Loss of anterior horn cells
  4. Demyelination with relative axonal preservation Correct answer.

Explanation

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune astrocytopathy targeting aquaporin-4 on astrocytes. Pathologically it shows demyelination, often with necrosis and cavitation, but relative axonal preservation compared to multiple sclerosis. The other options describe different diseases.

Question 22Neuropathology and Basic Neuroscience

A 60-year-old man with a history of alcohol use disorder and poor nutrition presents with ataxia and confusion. Autopsy shows symmetric lesions in the mammillary bodies and periaqueductal gray matter. Which vitamin deficiency is most likely responsible?

  1. Thiamine (vitamin B1) Correct answer.
  2. Vitamin E
  3. Niacin (vitamin B3)
  4. Vitamin B12

Explanation

Thiamine deficiency causes Wernicke encephalopathy, characterized by symmetric hemorrhagic and necrotic lesions in the mammillary bodies, thalamus, and periaqueductal gray. This is classically seen in chronic alcohol use and malnutrition.

Question 23Neuropathology and Basic Neuroscience

A 50-year-old man with hypertension and diabetes has a lacunar infarct in the internal capsule. Which pathological process most commonly underlies this type of infarct?

  1. Embolism from the heart
  2. Atherothrombosis of the middle cerebral artery
  3. Rupture of a berry aneurysm
  4. Lipohyalinosis of deep penetrating arteries Correct answer.

Explanation

Lacunar infarcts are small deep cerebral infarcts caused by occlusion of deep penetrating arteries, most often due to lipohyalinosis and microatheroma related to hypertension and diabetes. They are not typically caused by large artery atherosclerosis or cardiac embolism.

Question 24Neuropathology and Basic Neuroscience

A 65-year-old woman with a history of hypertension and atrial fibrillation presents with sudden onset of right-sided weakness and aphasia. CT scan shows a large hypodense area in the left middle cerebral artery territory. Microscopic examination of the infarcted tissue 24 hours after onset would most likely show which of the following?

  1. Red neurons Correct answer.
  2. Cavitation with glial scar
  3. Macrophage infiltration
  4. Luxol fast blue-positive macrophages

Explanation

Within 12–24 hours after an ischemic stroke, neurons undergo eosinophilic change (red neurons) with pyknosis and loss of Nissl substance. Macrophage infiltration and cavitation occur later, typically after several days to weeks.

Question 25Neuropathology and Basic Neuroscience

A 70-year-old man with a history of hypertension and diabetes dies of a myocardial infarction. Autopsy reveals multiple small cystic spaces in the basal ganglia and deep white matter. Microscopic examination shows thickened, hyalinized arterioles with surrounding tissue loss. Which of the following best describes this pathological finding?

  1. CADASIL
  2. Cerebral amyloid angiopathy
  3. Binswanger disease
  4. Lacunar state Correct answer.

Explanation

Lacunar state refers to the presence of multiple lacunar infarcts, which appear as small cystic spaces in deep brain structures such as the basal ganglia and white matter. It is associated with hypertension and diabetes, leading to lipohyalinosis of penetrating arteries.

Question 26Neuropathology and Basic Neuroscience

A 30-year-old woman presents with recurrent seizures. MRI shows a well-circumscribed lesion in the temporal lobe with a cystic component and a mural nodule. Histology shows a biphasic pattern with compacted bundles of spindle cells and loose microcystic areas. Which immunohistochemical marker is most likely positive in the spindle cells?

  1. Epithelial membrane antigen (EMA)
  2. NeuN
  3. Synaptophysin
  4. GFAP Correct answer.

Explanation

The described lesion is a pilocytic astrocytoma, which typically shows a biphasic pattern with compacted piloid areas and loose microcystic areas. The spindle cells are astrocytes and thus strongly express GFAP.

Question 27Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 24-year-old man is evaluated after a first generalized tonic-clonic seizure. Routine EEG shows 3 Hz generalized spike-and-wave discharges that activate during hyperventilation and are present while he is awake. Which electroclinical syndrome does this pattern most strongly suggest?

  1. Lennox-Gastaut syndrome
  2. Juvenile myoclonic epilepsy Correct answer.
  3. Childhood absence epilepsy
  4. Benign rolandic epilepsy

Explanation

Juvenile myoclonic epilepsy classically shows a normal background with 3 to 6 Hz generalized polyspike-and-wave and spike-and-wave discharges, often most prominent on awakening and provoked by sleep deprivation or hyperventilation. The combination of a first convulsion in an adolescent or young adult with this generalized discharge pattern supports the diagnosis, and the history usually reveals early-morning myoclonic jerks.

Question 28Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

During a routine EEG, a technologist asks the patient to hyperventilate for three minutes. Which normal response is expected in a healthy young adult?

  1. Suppression of the background to below 10 microvolts
  2. Appearance of 14 and 6 Hz positive bursts
  3. Persistent focal delta activity over the left temporal region
  4. High-voltage generalized slowing that builds during the maneuver and resolves within a minute of stopping Correct answer.

Explanation

Hyperventilation normally produces a buildup of high-voltage generalized slow activity, predominantly delta and theta, that is maximal near the end of the maneuver and clears quickly once breathing returns to normal. This response reflects cerebral vasoconstriction and is more prominent in younger patients.

Question 29Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 58-year-old woman has a 6-month history of progressive asymmetric resting tremor, rigidity, and bradykinesia. Her neurologist requests a needle EMG to look for a supportive electrophysiological sign. Which finding is most characteristic of Parkinson disease?

  1. Fibrillation potentials in the affected limb muscles
  2. Tremor bursts recurring at 8 to 12 Hz with synchronous antagonist activation
  3. Continuous motor unit firing at 20 Hz in all tested muscles
  4. Tremor bursts recurring at 4 to 6 Hz with alternating antagonist activation Correct answer.

Explanation

The resting tremor of Parkinson disease typically fires at about 4 to 6 Hz and shows alternating activation of agonist and antagonist muscles on multichannel recording. Essential tremor, by contrast, is faster and typically shows synchronous activation of antagonist muscles.

Question 30Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 35-year-old woman develops acute left facial weakness sparing the forehead. Needle EMG of the left frontalis shows normal motor unit recruitment. What does this finding best indicate?

  1. An old, fully reinnervated facial nerve lesion
  2. A neuromuscular junction disorder
  3. A central (upper motor neuron) lesion affecting the contralateral face Correct answer.
  4. A severe complete facial nerve axonal lesion

Explanation

Forehead muscles receive bilateral corticobulbar innervation, so a unilateral upper motor neuron lesion spares the upper face. Normal frontalis recruitment with lower facial weakness therefore points to a central lesion rather than a peripheral facial nerve palsy.

Question 31Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 42-year-old man has a 4-month history of progressive numbness of both hands and unsteadiness. Nerve conduction studies show absent median and ulnar sensory responses with preserved sural responses. What is the most appropriate interpretation?

  1. A demyelinating polyneuropathy with conduction block
  2. A non-length-dependent process such as a ganglionopathy or multifocal lesion Correct answer.
  3. A pure myopathy
  4. A length-dependent axonal polyneuropathy

Explanation

Length-dependent axonal polyneuropathies affect the legs before the arms, so the sural sensory response is lost earlier than the median and ulnar responses. Sparing of the sural response while upper limb sensory responses are absent indicates a non-length-dependent process, such as a sensory ganglionopathy or multifocal nerve disease.

Question 32Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 29-year-old woman has episodic vertigo and right-sided tinnitus. An EEG is requested during an acute attack of rotational vertigo. Which finding is most consistent with a vestibular origin of the symptoms?

  1. Right temporal spike-and-wave discharges
  2. Bursts of 14 and 6 Hz positive spikes
  3. Rhythmic temporal theta activity at 6 Hz that is abolished by eye opening Correct answer.
  4. Generalized 3 Hz spike-and-wave discharges

Explanation

Rhythmic mid-temporal theta of drowsiness, also called psychomotor variant, is a benign pattern seen in drowsiness and light sleep and is attenuated by eye opening or mental alertness. Recognizing this benign pattern prevents mislabeling a vestibular presentation as a temporal lobe seizure disorder.

Question 33Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 66-year-old man with diabetes has progressive weakness of the right hand and forearm. Nerve conduction studies show a normal right median sensory response, a low-amplitude right median compound muscle action potential, and normal ulnar studies. Needle EMG shows active denervation in the abductor pollicis brevis. Where is the lesion most likely located?

  1. Right median nerve in the forearm above the carpal tunnel Correct answer.
  2. Right C8 root
  3. Right lower trunk of the brachial plexus
  4. Right median nerve at the wrist

Explanation

A normal median sensory response with an abnormal median compound muscle action potential and denervation confined to the thenar muscles localizes the lesion proximal to the takeoff of the recurrent thenar motor branch but distal to the dorsal root ganglion. This pattern is characteristic of a median neuropathy in the forearm rather than at the wrist.

Question 34Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 54-year-old man is being evaluated for possible amyotrophic lateral sclerosis. Needle EMG shows widespread fasciculation potentials and active denervation in three limbs, but sensory nerve conduction studies are entirely normal. Which feature best supports ALS over a multifocal motor neuropathy?

  1. Widespread active denervation with normal sensory studies Correct answer.
  2. Symmetric distal sensory loss
  3. Presence of conduction block in multiple motor nerves
  4. Marked temporal dispersion of sensory responses

Explanation

ALS is a motor neuron disease, so EMG shows widespread active denervation and reinnervation while sensory nerve conduction remains normal. Multifocal motor neuropathy is a demyelinating disorder characterized by persistent motor conduction block, which is not a feature of ALS.

Question 35Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 31-year-old woman reports brief shock-like sensations down the back and legs when she flexes her neck. Which electrophysiological finding would best support a diagnosis of a demyelinating central nervous system disorder?

  1. Normal somatosensory evoked potentials from the upper limbs
  2. Normal brainstem auditory evoked potentials
  3. Absent lower limb somatosensory responses with normal upper limb responses
  4. Prolonged visual evoked potential P100 latency with normal amplitude Correct answer.

Explanation

A delayed P100 with preserved amplitude indicates demyelination of the visual pathway and is a classic evoked potential finding in multiple sclerosis. Lhermitte phenomenon in a young adult further raises suspicion of a demyelinating plaque in the cervical cord.

Question 36Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 47-year-old woman has a 2-week history of ascending symmetric weakness and areflexia after a diarrheal illness. Nerve conduction studies show prolonged distal latencies, slowed conduction velocities, and absent F waves in multiple nerves. What is the most likely diagnosis?

  1. Chronic inflammatory demyelinating polyradiculoneuropathy
  2. Inclusion body myositis
  3. Guillain-Barre syndrome Correct answer.
  4. Myasthenia gravis

Explanation

Acute ascending areflexic weakness after a gastrointestinal infection with demyelinating nerve conduction findings, including prolonged distal latencies and absent F waves, is characteristic of Guillain-Barre syndrome. The time course of two weeks strongly favors an acute inflammatory demyelinating polyneuropathy.

Question 37Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 70-year-old man with a history of hypertension has a sudden-onset right hemiparesis. An EEG is performed and shows focal polymorphic delta activity over the left hemisphere. What does this finding most likely represent?

  1. Normal aging-related slowing
  2. A benign variant of drowsiness
  3. A primary generalized epilepsy syndrome
  4. A destructive or structural lesion in the left hemisphere Correct answer.

Explanation

Focal polymorphic delta activity is a nonspecific sign of localized cerebral dysfunction, often caused by a structural lesion such as infarction, tumor, or abscess. In this clinical context it supports a left hemispheric lesion corresponding to the right hemiparesis.

Question 38Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 62-year-old man has progressive proximal weakness and muscle wasting. Needle EMG shows fibrillation potentials and positive sharp waves in proximal muscles, with small polyphasic motor unit potentials that fire early. What is the most likely interpretation?

  1. A myopathic process with active muscle fiber necrosis Correct answer.
  2. A chronic neurogenic process with reinnervation
  3. A disorder of neuromuscular transmission
  4. A pure sensory ganglionopathy

Explanation

Fibrillation potentials and positive sharp waves indicate active muscle fiber irritability, and small polyphasic motor units that fire early are the hallmark of myopathy. Together these findings suggest an active myopathic process rather than denervation or a transmission disorder.

Question 39Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 26-year-old man has a 3-year history of episodic loss of awareness. During a 72-hour ambulatory EEG he presses the event button during an episode, and the recording shows rhythmic 5 to 6 Hz theta activity over the left temporal region that evolves in frequency and amplitude. What is the most likely interpretation?

  1. A focal electrographic seizure of temporal lobe origin Correct answer.
  2. Eyelid flutter artifact
  3. A benign rhythmic temporal theta variant of drowsiness
  4. Muscle artifact from chewing

Explanation

A rhythmic discharge that evolves in frequency and amplitude over a single temporal region, coinciding with a clinical episode, represents a focal electrographic seizure. Benign temporal theta of drowsiness does not evolve and is not time-locked to clinical events.

Question 40Clinical Neuroimaging and Electrodiagnostics (EEG, EMG/NCS)

A 40-year-old woman has episodic muscle stiffness and spasms. Repetitive nerve stimulation at 20 Hz produces a marked increment in the compound muscle action potential amplitude. Which diagnosis is most likely?

  1. Myasthenia gravis
  2. Slow-channel congenital myasthenic syndrome
  3. Botulism
  4. Lambert-Eaton myasthenic syndrome Correct answer.

Explanation

Lambert-Eaton myasthenic syndrome is a presynaptic disorder in which high-frequency repetitive stimulation produces a marked increment in compound muscle action potential amplitude, often exceeding 100 percent. This reflects enhanced calcium influx and increased quantal release after the initial low-output state.

Question 41Cerebrovascular Disease and Stroke

A 68-year-old man is assessed 90 minutes after sudden onset of right hemiparesis and expressive aphasia. Non-contrast CT shows no haemorrhage and no early ischaemic change. Blood pressure is 175/95 mmHg, glucose 7.8 mmol/L, and there is no history of anticoagulation or recent surgery. Which is the most appropriate immediate management?

  1. Intravenous alteplase within the licensed time window Correct answer.
  2. Start aspirin 300 mg immediately and admit for observation
  3. Lower blood pressure to below 140/90 before any reperfusion decision
  4. Arrange MRI before considering any reperfusion therapy

Explanation

Intravenous thrombolysis with alteplase is indicated for disabling ischaemic stroke within 4.5 hours of onset once haemorrhage is excluded and contraindications are absent. A blood pressure of 175/95 mmHg is below the 185/110 mmHg threshold, so treatment can proceed. Glucose of 7.8 mmol/L is acceptable and does not preclude thrombolysis.

Question 42Cerebrovascular Disease and Stroke

Which artery is most commonly implicated in a lacunar infarct causing pure motor hemiparesis?

  1. Anterior communicating artery
  2. Cortical branches of the middle cerebral artery
  3. Posterior inferior cerebellar artery
  4. Lenticulostriate perforating arteries Correct answer.

Explanation

Lacunar infarcts result from occlusion of deep penetrating arteries, most often the lenticulostriate branches of the middle cerebral artery supplying the internal capsule and basal ganglia. These small vessel territories produce the classic lacunar syndromes such as pure motor stroke. Cortical and cerebellar arteries supply different territories and produce different syndromes.

Question 43Cerebrovascular Disease and Stroke

A 55-year-old woman has a sudden severe headache described as the worst of her life. CT head at 6 hours is normal. Which investigation is most appropriate next?

  1. MRI brain with contrast
  2. CT angiography of the cerebral vessels Correct answer.
  3. Lumbar puncture performed immediately
  4. Repeat non-contrast CT after 24 hours

Explanation

Sudden thunderclap headache with a normal CT at 6 hours still requires exclusion of subarachnoid haemorrhage, and CT angiography detects aneurysms and other vascular causes with high sensitivity in this setting. Modern practice favours vascular imaging over lumbar puncture when CT is negative but clinical suspicion remains high. Lumbar puncture is reserved for cases where vascular imaging is negative and xanthochromia would still change management.

Question 44Cerebrovascular Disease and Stroke

Which finding on carotid duplex most strongly predicts a future ischaemic stroke in an asymptomatic patient?

  1. A 70% stenosis of the internal carotid artery with a thin fibrous cap Correct answer.
  2. Tortuosity of the internal carotid artery
  3. Increased intima-media thickness of the common carotid artery
  4. A high-resistance waveform in the external carotid artery

Explanation

The degree of internal carotid stenosis and plaque morphology both predict stroke risk; severe stenosis with a thin fibrous cap indicates an unstable, rupture-prone plaque. Intima-media thickness is a weaker marker of general atherosclerotic burden. Flow patterns and vessel tortuosity are not established predictors of ipsilateral stroke.

Question 45Cerebrovascular Disease and Stroke

A patient develops a dense left hemiplegia and hemianopia 48 hours after an acute myocardial infarction. Which mechanism best explains this presentation?

  1. Embolism from a left ventricular mural thrombus Correct answer.
  2. Hypoperfusion from systemic hypotension alone
  3. Venous sinus thrombosis
  4. Rupture of a previously silent berry aneurysm

Explanation

Anterior myocardial infarction predisposes to left ventricular mural thrombus formation, and embolisation of this thrombus to the middle cerebral artery produces a large cortical infarct with hemiplegia and hemianopia. The delayed timing fits embolisation from an established thrombus. Hypoperfusion, aneurysm rupture and venous thrombosis do not fit this pattern and timing.

Question 46Cerebrovascular Disease and Stroke

Which is the recommended therapeutic target for blood pressure in the acute phase after intravenous thrombolysis for ischaemic stroke?

  1. Below 120/80 mmHg
  2. No specific target is required
  3. Below 185/110 mmHg before and below 180/105 mmHg after thrombolysis Correct answer.
  4. Below 220/120 mmHg

Explanation

Guidelines specify blood pressure must be below 185/110 mmHg before thrombolysis and maintained below 180/105 mmHg for at least 24 hours afterwards to reduce the risk of symptomatic intracerebral haemorrhage. Higher pressures increase bleeding risk while excessive lowering risks penumbral hypoperfusion. A target of 120/80 is unnecessarily aggressive in the acute phase.

Question 47Cerebrovascular Disease and Stroke

A 72-year-old with atrial fibrillation has a stroke while taking warfarin with an INR of 1.4. Which statement about anticoagulation resumption is most accurate?

  1. Aspirin should replace anticoagulation permanently in all patients with atrial fibrillation
  2. Anticoagulation is usually restarted after a short interval guided by infarct size and haemorrhagic transformation risk Correct answer.
  3. Anticoagulation should never be restarted after a cardioembolic stroke
  4. Warfarin should be restarted immediately at the same dose

Explanation

After cardioembolic stroke, anticoagulation is generally resumed after a delay determined by infarct size and the risk of haemorrhagic transformation, typically 1 to 3 days for small infarcts and longer for large ones. The decision balances recurrent embolism against bleeding. Permanent avoidance of anticoagulation or substitution with aspirin alone is not standard for atrial fibrillation.

Question 48Cerebrovascular Disease and Stroke

Which clinical feature most reliably distinguishes a transient ischaemic attack from a stroke?

  1. Presence of headache at onset
  2. Duration of symptoms less than one hour
  3. Complete resolution of focal neurological deficit without residual infarction on imaging Correct answer.
  4. Normal blood pressure at presentation

Explanation

A transient ischaemic attack is defined by transient focal neurological dysfunction without evidence of acute infarction on imaging, so complete clinical resolution plus absence of infarction is the defining feature. Symptom duration alone is not sufficient because prolonged symptoms can still resolve without infarction, and brief symptoms can accompany small infarcts. Headache and blood pressure are not discriminating features.

Question 49Cerebrovascular Disease and Stroke

A 60-year-old man has sudden painless loss of vision in one eye described as a curtain descending, lasting 10 minutes, with full recovery. Which underlying mechanism is most likely?

  1. Amaurosis fugax from embolic transient retinal ischaemia Correct answer.
  2. Retinal detachment
  3. Optic neuritis
  4. Acute angle-closure glaucoma

Explanation

Transient monocular visual loss with a curtain-like descent is amaurosis fugax, typically caused by emboli from the ipsilateral internal carotid artery to the retinal artery. It is a warning sign of carotid or cardiac embolism and requires urgent vascular assessment. The other options cause persistent visual loss or pain rather than transient monocular loss.

Question 50Cerebrovascular Disease and Stroke

Which of the following is the strongest indication for urgent carotid endarterectomy?

  1. Asymptomatic 80% stenosis in a patient with a life expectancy of two years
  2. Symptomatic 70% stenosis in the appropriate territory within the last two weeks Correct answer.
  3. Asymptomatic 50% stenosis detected on screening
  4. Symptomatic 30% stenosis with a completed large infarct

Explanation

Carotid endarterectomy provides the greatest benefit in symptomatic patients with 70% to 99% stenosis when performed within two weeks of the qualifying event, because the early recurrence risk is highest. Symptomatic moderate stenosis may benefit from surgery in selected cases, but severe symptomatic stenosis is the clearest indication. Asymptomatic stenosis is managed selectively and with lower absolute benefit.