Isaacs syndrome

Abstract

A 57-year-old retired factory worker was admitted to the accident and emergency department complaining of a 3-month history of painful stiffness of his hands and toes. In addition he complained of generalized weakness, numbness and a tingling sensation of both his upper and lower limbs as well as weight loss. He was keen to mention that his stiffness had been long lasting and was even present during sleep. There was no significant past medical history. On general examination a mild weakness affecting the distal region of all four limbs were noted in addition to myokymia. He was also remarkably unsteady on his feet. There was no evidence of excessive perspiration or muscle wasting. A routine full blood count, urea and electrolytes, liver function and creatinine kinase were unremarkable. The patient was referred for electromyography testing which demonstrated evidence of neuromyotonia and myokymia. Antibody testing to voltage-gated potassium channels was not performed. The patient was prescribed phenytoin 50 mg twice daily. After 1 week his symptoms had improved substantially and at 1-month follow up the patient was practically asymptomatic.