Ptosis and Other Features

A common presenting feature is ptosis, which is often partial and may be unilateral.

The extraocular muscles are affected initially in about 50% and, eventually, in 90% of cases.

Ptosis improves after a period of sleep (the sleep test) or with the application of ice on the lid (the ice test).

The pupils are typically spared in MG. The face may appear expressionless. The mouth may be open and the patient may have to support the jaw with their hand.
Ocular muscle weakness may be the only feature throughout the course in about 10% of patients.
Deep tendon reflexes are intact or may be brisk.
There is no objective sensory deficit and no deficit in cerebellar function.
There may be dysphonia from laryngeal weakness.
There may be dysphagia from weakness of muscles involved in chewing and swallowing.

Learning bite

Ptosis is the commonest physical sign in MG. It is seen in up to 90% of patients. The pupil is unaffected.