How (Localizing Lesions)
An elderly patient develops acute right hemiplegia and right lower facial weakness. She can speak fluently but does not respond to questions.
What is the left inferior frontal gyrus (Broca’s area)?
Key concept: Expressive aphasia = intact comprehension, impaired repetition & fluency. Usually due to left MCA superior division infarct.
A 19-year-old female has early morning myoclonic jerks, especially after sleep deprivation. What is the diagnosis?
What is juvenile myoclonic epilepsy?
Step 2 loves this – first seizure often is generalized tonic-clonic triggered by sleep loss.
Ptosis that worsens throughout the day and improves with rest is most consistent with this diagnosis.
What is myasthenia gravis?
Autoantibodies against nicotinic acetylcholine receptors or MuSK.
A 28-year-old woman develops sudden vision loss in one eye and pain with eye movement. Fundoscopy is normal. Diagnosis?
What is optic neuritis?
Often the presenting sign of multiple sclerosis; MRI brain + spine is next step.
A patient presents with a resting tremor, bradykinesia, and rigidity. What is the neurotransmitter imbalance responsible?
What is decreased dopamine in the substantia nigra?
Classic triad: pill-rolling tremor, cogwheel rigidity, shuffling gait.
A 59-year-old has loss of pain and temperature sensation in the right arm and leg, right-sided Horner syndrome, and hoarseness.
What is the left lateral medulla (Wallenberg syndrome)?
High-yield for Step 2: Lateral medullary syndrome = PICA infarct.
A patient with a postictal period, tongue biting, and urinary incontinence most likely had this type of event.
What is a generalized tonic-clonic seizure?
Distinguish from syncope – no postictal state or incontinence
A patient presents with weakness that improves with exertion, hyporeflexia, and autonomic dysfunction. What is the likely diagnosis?
What is Lambert-Eaton myasthenic syndrome?
Associated with small cell lung cancer. Antibodies to presynaptic Ca²⁺ channels.
A patient with MS has worsening symptoms after a hot shower or exercise. This phenomenon is called:
Answer: What is Uhthoff’s phenomenon?
Classic Step 2 detail — transient symptom worsening with increased body temp.
A young man on antipsychotics develops involuntary upward eye deviation and neck muscle spasm. What is the diagnosis and treatment?
What is acute dystonia; treat with benztropine or diphenhydramine.
EPS from dopamine blockade — know all 4 types (dystonia, akathisia, parkinsonism, tardive).
A patient presents with left hemiparesis, left hemisensory loss, and left homonymous hemianopia with right gaze preference. The infarct is in this artery.
What is the right MCA?
"Gaze preference toward lesion" + motor/sensory/language signs = classic MCA infarct.
A 6-month-old boy presents with symmetric spasms and developmental regression. EEG shows hypsarrhythmia. First-line treatment?
What is ACTH (adrenocorticotropic hormone)?
West syndrome = infantile spasms. High mortality/morbidity if untreated.
A patient with new bilateral ptosis, anhidrosis, and dry mouth after eating home-canned foods has what disease mechanism?
What is inhibition of presynaptic acetylcholine release by botulinum toxin?
Botulism causes descending flaccid paralysis.
A CSF analysis reveals oligoclonal bands and elevated IgG index. What is the most likely diagnosis?
What is multiple sclerosis?
CSF findings support diagnosis but MRI is the most sensitive test.
This condition features both chorea and psychiatric symptoms in a patient with a family history of similar illness.
What is Huntington disease?
CAG trinucleotide repeat; caudate atrophy on imaging.
A man is found with bilateral lower extremity weakness, urinary incontinence, and gait apraxia. CT head shows enlarged ventricles.
What is normal pressure hydrocephalus (NPH)?
Classic triad: wet, wobbly, wacky.
EEG during absence seizures typically shows this classic finding.
What is 3-Hz spike-and-wave discharges?
Ethosuximide is first-line. Differentiate from focal seizures.
A 40-year-old man has trouble releasing his grip after shaking hands. EMG shows myotonic discharges. Likely diagnosis?
What is myotonic dystrophy?
CTG trinucleotide repeat; also see frontal balding, cataracts, testicular atrophy.
A patient with bilateral leg weakness and a sensory level at the umbilicus develops urinary retention. MRI shows spinal cord inflammation. Diagnosis?
Answer: What is transverse myelitis?
Strong association with MS and neuromyelitis optica.
A patient with parkinsonism, early falls, vertical gaze palsy, and poor levodopa response has:
What is progressive supranuclear palsy?
Look for postural instability and vertical gaze issues = classic board clue.
This term describes when a patient with a penetrating head injury loses the ability to make purposeful movements despite normal strength.
What is apraxia?
Seen in dominant parietal lobe lesions; especially left posterior parietal cortex.
Name two major differences between a psychogenic non-epileptic seizure (PNES) and a true tonic-clonic seizure.
What are preserved awareness and side-to-side head movement (or asynchronous limb movement)?
Step 2 often asks about PNES in context of no EEG findings + emotional triggers.
A patient presents with rapidly progressive ascending weakness after diarrhea. CSF shows albuminocytologic dissociation. Diagnosis?
What is Guillain-Barré syndrome?
High protein, normal WBC in CSF. Treat with IVIG or plasmapheresis.
This demyelinating disease presents similarly to MS but with longitudinally extensive spinal cord lesions and positive aquaporin-4 antibodies.
What is neuromyelitis optica (Devic disease)?
More aggressive than MS; requires different treatment (immunosuppression, not just MS DMTs).
A 35-year-old man has dystonia, tremor, and psychiatric changes. Slit lamp shows a brown ring at the cornea. What is the treatment?
What is chelation therapy with penicillamine (Wilson disease)?
Copper overload — also affects liver. Always check ceruloplasmin.