EM@3AM: Cortical Hand-Knob Stroke Mimicking Peripheral Nerve Injury
When you encounter sudden, isolated weakness confined only to finger and thumb movement with preserved sensation and proximal strength, strongly consider a cortical infarct rather than assuming a peripheral neuropathy. While this presentation is highly suggestive of a central cause, remember that thorough evaluation for other stroke signs like facial droop or dysarthria is still warranted. If the suspicion remains high despite negative workup, keep imaging in your differential.
This review focuses on 'hand-knob strokes,' a specific, small cortical infarct pattern affecting the precentral gyrus area that controls finger and thumb motor function. These lesions can present with an isolated distal hand paralysis, which is clinically deceptive because it strongly mimics a peripheral nerve injury. The key diagnostic challenge arises when a patient presents with sudden, painless weakness limited specifically to the fingers and thumb, while proximal upper extremity strength and sensation remain intact. Recognizing this central etiology is crucial because the initial workup might otherwise lead down a rabbit hole investigating peripheral causes like carpal tunnel syndrome or radial nerve palsy. It serves as an important reminder for the ED setting.