Purpose: We describe the anaesthetic management of a patient with the autosomal dominant inherited disease, normokalaemic periodic paralysis. The disease results in intermittent bouts of limb and respiratory muscular weakness in association with hypothermia, stress, prolonged fasting or exercise. Unlike hypokalaemic and hyperkalaemic periodic paralysis, the more common variants of the disease, normokalaemic periodic paralysis is not accompanied by alterations in the plasma potassium concentration.
Clinical features: A five-year-old boy presented for emergency scrotal exploration. He had a family history of periodic paralysis and had experienced previous episodes of weakness, two of which had required hospitalization for respiratory distress. On admission there was no evidence of weakness and serum potassium concentration was 4.2 mMol.L-1. A spinal anaesthetic was performed and the procedure was uncomplicated by muscle paralysis above the level of the spinal block.
Conclusion: Avoidance of known precipitating factors and judicious use of neuromuscular blocking drugs has been advocated in patients with this disorder presenting for surgery. In appropriate circumstances, spinal anaesthesia represents a useful option in patients with normokalaemic periodic paralysis.