Neurology questions terrify students. Long vignettes. Weird physical exam findings. Multiple cranial nerves.
But here is the framework that works: Localize the lesion first. Everything else follows.
The 5-Step Framework
Step 1: Upper or lower motor neuron?
- UMN: Hyperreflexia, spasticity, Babinski
- LMN: Hyporeflexia, flaccidity, fasciculations
Step 2: Where is the lesion?
- Cortex (stroke, tumor) → contralateral weakness (face > arm > leg)
- Internal capsule → contralateral weakness (equal face/arm/leg)
- Brainstem → ipsilateral cranial nerve + contralateral body (“crossed findings”)
- Spinal cord → level, bilateral, bowel/bladder changes
Step 3: Add sensory findings
- Posterior cord (dorsal columns) → loss of vibration/proprioception
- Spinothalamic tract → loss of pain/temp
- Lateral corticospinal → motor (UMN)
Step 4: Cranial nerves = brainstem map
- CN3 (midbrain)
- CN5,6,7 (pons)
- CN9,10,11,12 (medulla)
Step 5: Put it together
Example: Right arm/leg weakness + left facial numbness → Left brainstem lesion (crossed findings) → Think lateral medullary (PICA) stroke.