Neural hyperexcitability in hyperkalemic periodic paralysis.

An electrophysiologic study of peripheral nerve excitability was performed in patients with hyperkalemic periodic paralysis (HPP) and in normal controls. It was found that a marked degree of neural hyperexcitability existed in all patients with HPP who showed cold sensitivity. The results suggest involvement of the nerve cell membrane in the proximal segments of peripheral nerve. This testing method may be of value in differentiating the cold-sensitive variant of HPP.