Finger flexion resembling focal dystonia in Isaacs' syndrome.

We describe a patient with a 5-month history of gradually progressive painless flexion of the left ring finger associated with cramps in both thighs. She has severe chronic obstructive pulmonary disease and was on salbutamol. Serum anti-voltage-gated potassium channel antibodies was positive. Electromyography showed generalized neuromyotonia and myokymic discharges. The cramps were partially relieved by phenytoin. We would like to highlight that finger flexion resembling dystonia can be a presenting sign of Isaacs' syndrome.