Reversible electrophysiological abnormalities in hypokalemic paralysis: Case report of two cases
A 52-year-old male with no past medical illness presented with flaccid areflexic quadriparesis of 1 day duration. There was no sensory loss, cranial nerve involvement, bladder disturbance, or higher function disturbance. The power in upper limb muscle groups was 2/5 and in the lower limb muscle groups was 3/5. The ECG done in the emergency ward showed U waves. He was evaluated for electrolyte abnormalities (suspecting a possible diagnosis of hypokalemic paralysis) and while the reports were still pending, he underwent NC study. The NC study showed significant reduction in CMAP amplitudes of all motor nerves. However, distal latencies and conduction velocities of motor nerves were normal. F-wave latencies were non recordable in all tested motor nerves. SNAP amplitudes were also normal. Based on the electrophysiological findings, an alternate diagnosis of AMAN form of GBS was also considered. The serum potassium report was 2.0 mmol/L. With administration potassium (160 meq intravenous over 24 h followed by 60 meq per day in three divided doses orally in form of potassium chloride), the patient showed dramatic clinical improvement. Based on this, the original diagnosis of hypokalemic paralysis with quadriparesis was confirmed. NC study was repeated 24 h after the initial study, by which time the patient's motor power was back to normal and serum potassium was 3.9 mmol/L. Repeat NC study was found to be normal. The secondary causes of hypokalemia including thyrotoxicosis, renal tubular acidosis, gastrointestinal loss were ruled out (FT3-3.09 pg/mL, FT4-1.03 ng/dL, TSH − 2.90 uIU/mL, arterial pH − 7.4) The short and long duration exercise test to document channelopathy as cause of hypokalemia was planned, but patient did not give consent for the same. As no definite secondary cause of hypokalemia could be found the patient was not put on any prophylactic therapy. The patient was advised against heavy manual labor and avoiding heavy carbohydrate meals.\nThe NC study report before and after correction of hypokalemia and recovery of muscle power depicting the changes in the CMAP of the motor nerves.\nAs there was no asymmetry between nerve conduction findings of left and right side, only right-sided nerves are described for sake of convenience [].