[Periodic paralysis. Clinical analysis in 20 patients].

Twenty patients with periodic paralysis were evaluated and the aspects studied included epidemiological data, clinical manifestations, ancillary tests, treatment and evolution. Sixteen patients had the hypokalemic form (5 familiar, 5 sporadic, 5 thyrotoxic and 1 secondary). No patient with the normokalemic form was detected. Predominance of men was found (14 patients), especially in the cases with hyperthyroidism (5 patients). No thyrotoxic patient was of oriental origin. Only 4 patients had the hyperkalemic form (3 familiar, 1 sporadic). Attacks of paralysis began during the first decade in the hyperkalemic form and up to the third decade in the hypokalemic. In both forms the attacks occurred preferentially in the morning with rest after exercise being the most important precipitating factor. Seventy five percent of the hyperkalemic patients referred brief attacks (< 12 hours). Longer attacks were referred by 43% of the hypokalemic patients. The majority of the attacks manifested with a generalized weakness mainly in legs, and its frequency was variable. Creatinokinase was evaluated in 10 patients and 8 of them had levels that varied from 1.1 to 5 times normal. Electromyography was done in 6 patients and myotonic phenomenon was the only abnormality detected in 2 patients. Carbonic anhydrase inhibitors, especially acetazolamide, were used for prophylactic treatment in 9 patients with good results in all. Although periodic paralysis may be considered a benign disease we found respiratory distress in 5 patients, permanent myopathy in 1, electrocardiographic abnormalities during crises in 4; death during paralysis occurred in 2. Therefore correct diagnosis and immediate treatment are crucial. This study shows that hyperthyroidism is an important cause of periodic paralysis in our country, even in non oriental patients. Hence endocrine investigation is mandatory since this kind of periodic paralysis will only be abated after return to the euthyroid state.