Not all patients with myasthenia gravis are grave

Myasthenia gravis (MG) is another autoimmune disease in that the body is tricked to think acetylcholine receptor, an important component in the nerve conduction, is ‘foreign’ and dutifully attacks it.

There is a gap between nerves or between nerve and muscle, through which the conduction of impulse depends on chemical substances called neurotransmitters, in the case of MG, it is acetylcholine between nerve and muscle.

There are two clinical forms of myasthenia gravis: (1) ocular form (affects the eyes only)  and (2) generalized form (may affect any skeletal muscles on the whole body) Myasthenia means “muscle debility”; Latin gravis means “serious” and having a generalized form of myasthenia gravis is indeed serious (grave); but this dreaded name makes the more limited ocular form seem more serious than it actually is.

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About half (50%) of patients with purely ocular MG are seropositive (i.e. has acetylcholine antibody in the blood).  About 85% of patients with generalized form, and virtually all patients (98-100%) with MG and thymoma (tumor in thymus) have this antibody.

About 10-15% of MG patients have thymoma, and about 85% have thymic hyperplasia (i.e. thymus gland overgrow, but there is no tumor) It is postulated that all patients with myasthenia gravis have B cells that produces acetylcholine antibody.

Most experts feel it is beneficial to surgically remove thymus gland (whether thymic hyperplasia or thymoma) and it may take many years to see the benefit of thymectomy (surgical removal of thymus).

It is well known that a given disease may present with a widely varying severity and course.  Another example is amyotrophic lateral sclerosis (better known as Lou Gehrig’s disease in the U.S.) in which the motor neurons are destroyed.  Lou Gehrig succumbed to it less than two years after he proclaimed that he was “the luckiest man on the face of the Earth.” in his touching farewell address at Yankee Stadium.  And yet Stephen Hawking has lived with this disease for more than 40 years and is still going on ‘strong’ in his quest in the fields of cosmology and quantum gravity.