NEET SS Neurology (DM) Syllabus

Which antiseizure drugs are best avoided in absence and myoclonic seizures because they may worsen them?

Sodium channel blockers/GABAergics such as carbamazepine, oxcarbazepine, phenytoin, gabapentin, pregabalin, and vigabatrin can worsen absence and myoclonic seizures. Use broad-spectrum agents (valproate, lamotrigine, levetiracetam) instead.

Name the characteristic serious idiosyncratic reactions of carbamazepine, lamotrigine, and valproate.

Carbamazepine: SJS/TEN (HLA-B*1502 in Asians), aplastic anemia, hyponatremia. Lamotrigine: SJS/TEN (risk increased by rapid titration and co-administration with valproate). Valproate: hepatotoxicity, pancreatitis, hyperammonemic encephalopathy, teratogenicity (neural tube defects).

Define status epilepticus by the operational time thresholds (t1 and t2).

t1 (when treatment should start): continuous seizure for >=5 minutes, or >=2 seizures without recovery of consciousness. t2 (risk of long-term consequences/neuronal injury): >=30 minutes for convulsive status epilepticus.

Outline the staged pharmacologic management of convulsive status epilepticus.

Stage 1 (emergent): IV benzodiazepine (lorazepam 0.1 mg/kg or IM midazolam). Stage 2 (urgent control): IV fosphenytoin/phenytoin, valproate, or levetiracetam. Stage 3 (refractory): anesthetic infusion (midazolam, propofol, or thiopental) with EEG burst-suppression.

What are the brainstem reflexes that must be absent to declare brain death?

Absent pupillary light reflex, corneal reflex, oculocephalic (doll's eye) reflex, oculovestibular (cold caloric) reflex, gag and cough reflexes, and absent motor response to pain in cranial nerve distribution. Plus coma of known irreversible cause and a positive apnea test.

Describe the apnea test for brain death confirmation.

After preoxygenation, the ventilator is disconnected; PaCO2 is allowed to rise. The test is positive (consistent with brain death) if there is no respiratory effort despite PaCO2 >=60 mmHg (or a rise of >=20 mmHg above baseline).

How does the Glasgow Coma Scale score, and what total indicates coma?

GCS scores Eye (1-4), Verbal (1-5), Motor (1-6), total 3-15. A score of <=8 indicates coma and is the threshold for considering intubation for airway protection.

What pupillary findings localize the lesion in a comatose patient: pinpoint, mid-position fixed, unilateral dilated?

Pinpoint reactive pupils: pontine lesion (or opioids). Mid-position fixed pupils: midbrain lesion. Unilateral fixed/dilated pupil: uncal (CN III) herniation. Bilateral fixed dilated: severe global injury or anticholinergics.

What are the four cardinal motor features of Parkinson's disease (TRAP)?

Tremor (resting, 4-6 Hz 'pill-rolling'), Rigidity (cogwheel), Akinesia/bradykinesia (required for diagnosis), and Postural instability (later feature). Asymmetric onset is typical.

List 'red flag' features suggesting Parkinson-plus syndromes rather than idiopathic Parkinson's disease.

Early postural instability/falls and vertical gaze palsy (PSP), early autonomic failure/cerebellar signs (MSA), early dementia with visual hallucinations (DLB), asymmetric apraxia/alien limb (CBD), poor levodopa response, and symmetric onset.

What is the pathological hallmark of Parkinson's disease and the neurotransmitter deficit?

Loss of dopaminergic neurons in the substantia nigra pars compacta with Lewy bodies (alpha-synuclein aggregates), causing dopamine deficiency in the nigrostriatal pathway.

Distinguish chorea, athetosis, ballism, dystonia, and myoclonus.

Chorea: brief, random, flowing involuntary movements. Athetosis: slow, writhing distal movements. Ballism: large-amplitude flinging proximal movements (hemiballism = contralateral subthalamic nucleus lesion). Dystonia: sustained co-contraction causing abnormal postures. Myoclonus: sudden, brief shock-like jerks.

What are the genetic and clinical features of Huntington's disease?

Autosomal dominant CAG trinucleotide repeat expansion in the HTT gene on chromosome 4 (>=36 repeats), showing anticipation. Features: chorea, behavioral/psychiatric changes, and progressive dementia; caudate atrophy ('boxcar' ventricles) on imaging.

What distinguishes Wilson's disease as a treatable movement disorder, and its diagnostic markers?

Autosomal recessive ATP7B mutation causing copper accumulation. Features: dystonia, tremor ('wing-beating'), dysarthria, parkinsonism, plus hepatic and psychiatric features. Markers: low serum ceruloplasmin, high 24-hr urinary copper, Kayser-Fleischer rings. Treated with chelation (penicillamine/trientine) and zinc.

Compare the typical clinical and pathological features of Alzheimer's disease vs frontotemporal dementia.

Alzheimer's: early episodic memory loss, amyloid plaques and neurofibrillary (tau) tangles, medial temporal/hippocampal atrophy. FTD: early behavioral/personality change or progressive aphasia, relatively preserved early memory, frontotemporal atrophy with tau or TDP-43 inclusions.

What are the core clinical features of Dementia with Lewy Bodies (DLB)?

Fluctuating cognition, recurrent well-formed visual hallucinations, spontaneous parkinsonism, and REM sleep behavior disorder; marked neuroleptic sensitivity. Pathology: cortical Lewy bodies (alpha-synuclein). The '1-year rule' separates DLB (cognition before/with parkinsonism) from PD dementia (motor first).

What clinical triad and imaging finding characterize normal pressure hydrocephalus (a reversible dementia)?

Triad ('wet, wobbly, wacky'): gait apraxia (magnetic gait), urinary incontinence, and dementia. Imaging shows ventriculomegaly out of proportion to atrophy (high Evans index). Improvement after large-volume CSF tap predicts response to shunting.

Describe the classic CSF finding in Guillain-Barre syndrome and its diagnostic significance.

Albuminocytologic dissociation: elevated CSF protein with normal cell count (<10 cells/uL), typically appearing after the first week. GBS is an acute inflammatory demyelinating polyradiculoneuropathy with ascending areflexic weakness; nerve conduction shows demyelination.

How do axonal and demyelinating peripheral neuropathies differ on nerve conduction studies?

Demyelinating: marked slowing of conduction velocity, prolonged distal latencies, conduction block, and prolonged/absent F-waves with relatively preserved amplitudes. Axonal: reduced CMAP/SNAP amplitudes with relatively preserved conduction velocity.

Give the classic pattern and common causes of a sensorimotor symmetric polyneuropathy versus mononeuritis multiplex.

Distal symmetric 'glove-and-stocking' polyneuropathy: diabetes, alcohol, B12 deficiency, uremia, drugs. Mononeuritis multiplex (asymmetric, multiple named nerves): vasculitis (PAN, EGPA), diabetes, leprosy, sarcoidosis.

What antibody-defined variants underlie Guillain-Barre syndrome subtypes AMAN and Miller Fisher?

AMAN (acute motor axonal neuropathy): anti-GM1/GD1a antibodies, often post-Campylobacter. Miller Fisher syndrome (ophthalmoplegia, ataxia, areflexia): anti-GQ1b antibodies.

Contrast myasthenia gravis and Lambert-Eaton myasthenic syndrome (LEMS) by antibody, weakness pattern, and repetitive stimulation.

MG: anti-AChR (or anti-MuSK) antibodies, fatigable weakness worsening with activity, ocular/bulbar onset, decrement on low-frequency repetitive nerve stimulation; associated with thymoma. LEMS: anti-VGCC (P/Q-type) antibodies, proximal weakness that improves with exercise, autonomic features, incremental (facilitation) response on high-frequency/post-exercise stimulation; associated with small cell lung cancer.

What is a myasthenic crisis and its acute management?

Severe MG weakness causing respiratory failure (often precipitated by infection, surgery, or drugs). Management: airway/ventilatory support, IVIG or plasmapheresis for rapid effect, treat precipitant; corticosteroids may transiently worsen weakness initially.

Describe the EMG triad/pattern of myopathy versus neuropathy.

Myopathy: small-amplitude, short-duration, polyphasic motor unit potentials with early (full) recruitment. Neurogenic (denervation): large-amplitude, long-duration, polyphasic units with reduced recruitment, plus fibrillations and positive sharp waves on needle EMG.

What features distinguish upper from lower motor neuron involvement in amyotrophic lateral sclerosis (ALS)?

UMN signs: spasticity, hyperreflexia, extensor plantar (Babinski), pseudobulbar affect. LMN signs: muscle wasting, fasciculations, weakness, hyporeflexia. ALS uniquely combines both UMN and LMN signs without sensory loss or sphincter involvement.

What is the electrodiagnostic phenomenon of myotonia and which disease classically shows it?

Myotonia is impaired muscle relaxation; needle EMG shows 'myotonic discharges' (waxing-waning amplitude/frequency, 'dive-bomber' sound). Classic in myotonic dystrophy (DM1, CTG repeat in DMPK gene) and myotonia congenita.

What does decrement on repetitive nerve stimulation and jitter on single-fiber EMG indicate?

A >10% decrement in CMAP amplitude on low-frequency (2-3 Hz) repetitive nerve stimulation indicates a neuromuscular junction (postsynaptic) defect like MG. Increased jitter/blocking on single-fiber EMG is the most sensitive NMJ test.

What CSF and MRI findings support multiple sclerosis, and what diagnostic criteria are used?

CSF shows oligoclonal bands (not in serum) and raised IgG index. MRI shows periventricular, juxtacortical, infratentorial, and spinal cord T2 lesions ('Dawson's fingers'). McDonald criteria require dissemination in space and time.

Differentiate multiple sclerosis from neuromyelitis optica spectrum disorder (NMOSD).

NMOSD: aquaporin-4 (AQP4-IgG) antibodies, longitudinally extensive transverse myelitis (>=3 vertebral segments), severe optic neuritis, area postrema syndrome; brain MRI often spares the typical MS pattern. MS: shorter cord lesions, oligoclonal bands, Dawson's fingers; treated differently (NMOSD worsened by some MS drugs like beta-interferon).

How is an acute MS relapse treated versus disease-modifying therapy goals?

Acute relapse: high-dose IV methylprednisolone (e.g., 1 g/day x 3-5 days); plasma exchange for steroid-refractory severe relapses. DMTs (interferons, glatiramer, dimethyl fumarate, natalizumab, ocrelizumab, fingolimod) reduce relapse rate and disability progression in relapsing-remitting MS.

List the diagnostic criteria features and first-line acute treatment of migraine.

Migraine without aura: >=5 attacks of unilateral, pulsating, moderate-severe headache lasting 4-72 hours, aggravated by activity, with nausea/vomiting or photophobia and phonophobia. Acute treatment: NSAIDs/triptans (or gepants/ditans); prophylaxis with beta-blockers, topiramate, amitriptyline, or CGRP antagonists.

What are the distinguishing features and treatment of cluster headache?

Severe strictly unilateral orbital/temporal pain in attacks of 15-180 minutes, with ipsilateral autonomic features (lacrimation, conjunctival injection, ptosis, rhinorrhea) and restlessness, occurring in clusters. Acute: 100% oxygen and subcutaneous sumatriptan; prophylaxis with verapamil.

What CSF and clinical features distinguish bacterial, viral, and tuberculous meningitis?

Bacterial: high neutrophils, very high protein, very low glucose (<40% of serum). Viral: lymphocytic pleocytosis, mildly raised protein, normal glucose. Tuberculous: lymphocytic, very high protein, low glucose, with high CSF ADA and basal meningeal enhancement; subacute onset.