The sleep test for myasthenia gravis. A safe alternative to Tensilon.

The diagnosis of myasthenia gravis is usually confirmed by a Tensilon test, which can be complicated by cholinergic side effects that include cardiopulmonary arrest. An alternative, the Sleep test, based on the characteristic of myasthenia that symptoms and signs worsen with fatigue and improve after a period of rest, is safe, moderately sensitive, and specific. The diagnosis of myasthenia can be confirmed by observing resolution of ptosis or ophthalmoparesis immediately after a 30-minute period of sleep; the reappearance of the myasthenic signs over the next 30 seconds to 5 minutes adds further confirmation.