Neurologic System
Core concepts
Stroke: thrombolysis is considered up to 4.5 hours from onset after noncontrast head CT excludes hemorrhage, and thrombectomy extends later for selected large-vessel occlusions. Check glucose first because hypoglycemia mimics stroke. Sudden thunderclap headache suggests subarachnoid hemorrhage; CT is highly sensitive early, with lumbar puncture for xanthochromia if CT is negative and suspicion persists.
Seizures: status epilepticus is treated first with a benzodiazepine, then a longer-acting agent such as levetiracetam or fosphenytoin.
Neuromuscular disease is distinguished by pattern. Myasthenia gravis causes fatigable weakness with ptosis and diplopia and is confirmed by acetylcholine receptor antibodies; crisis treatment is plasmapheresis or intravenous immunoglobulin, and aminoglycosides are avoided. Guillain-Barre syndrome causes ascending symmetric weakness with areflexia and cerebrospinal fluid albuminocytologic dissociation; monitor forced vital capacity.
Vertigo: benign paroxysmal positional vertigo is provoked by head movement, diagnosed by Dix-Hallpike, and treated by Epley repositioning.
Meningitis: obtain blood cultures and start empiric vancomycin plus ceftriaxone promptly, adding ampicillin when the patient is older than 50 or immunocompromised; head CT before lumbar puncture only when focal deficits, seizures, or papilledema are present.
Traps
- Skipping the glucose check in a patient with sudden focal deficits.
- Diagnosing Bell palsy when the forehead is spared, which indicates an upper motor neuron lesion.
- Delaying antibiotics for meningitis to obtain imaging without a contraindication.
Rule of thumb
Weakness that worsens with use and improves with rest, plus ptosis, is myasthenia gravis; weakness that ascends symmetrically over days with absent reflexes is Guillain-Barre.