Sural sparing reversible sensorimotor abnormalities in hypokalemia: A close mimic of GBS

Abstract

Nerve conduction studies (NCS) in hypokalemic paralysis usually show decreased compound muscle action potential (CMAP) which improves with correction of hypokalemia and normalizes in between the attacks. Inactivity of Na+ K+ ATPase pump due to hypokalemia results in decreased excitability of muscle fibers resulting in reduced CMAP on NCS. Sensory symptoms, as well as abnormalities in sensory NCS is a rare phenomenon. Here we describe a 40-year-old male who presented with acute onset rapidly progressive ascending quadriparesis with type 2 respiratory failure due to hypokalemia following hepatorenal dysfunction. NCS done before hypokalemia correction, suggested sural sparing with generalized reduced CMAPs, nonrecordable median and ulnar nerves sensory nerve action potential (SNAP) and abnormal F waves. After hypokalemia correction there was improvement in CMAPs as well as SNAPs. Thus, hypokalemia can present as an axonal sensorimotor involvement with sural sparing on NCS study similar to Guillain-Barré syndrome subtype.