The familial periodic paralyses are a subgroup of diseases referred to as skeletal muscle channelopathies. The common mechanism for these diseases appears to be a persistent sodium inward current depolarization that causes muscle membrane inexcitability and subsequent muscle weakness (Table 23-2: Clinical Features of Familial Periodic Paralysis).

1. Hyperkalemic periodic paralysis is characterized by episodes of myotonia and muscle weakness that may last for hours after exposure to a trigger (see Table 23-2: Clinical Features of Familial Periodic Paralysis).
2. Hypokalemic periodic paralysis is caused by a defect in the calcium ion channel (see Table 23-2: Clinical Features of Familial Periodic Paralysis).
3. Management of Anesthesia
   1. The primary goal of the perioperative management of patients with both forms of periodic paralysis is the maintenance of normal potassium levels and avoidance of events that precipitate muscle weakness (alkalosis owing to hyperventilation, carbohydrate loads, hypothermia).
   2. Short-acting muscle relaxants are preferred, and the response should be monitored with a peripheral nerve stimulator. SCh should be avoided because it may enhance potassium release from skeletal muscle cells.
   3. The ECG should be monitored for evidence of hypokalemia and associated cardiac dysrhythmias. (Serum potassium concentration should be measured during prolonged operations.)
   4. Avoidance of carbohydrate loads, hypothermia, and excessive hyperventilation is prudent.

Rare Coexisting Diseases

1. Musculoskeletal Diseases
2. The Myotonias
3. Familial Periodic Paralysis
4. Myasthenia Gravis
5. Guillain-Barré Syndrome (Polyaradiculoneuritis)
6. Central Nervous System Diseases
7. Inherited Disorders
8. Anemias
9. Collagen Vascular Diseases
10. Skin Disorders