BOF: 28
A 30-year-old female presents with a history of weakness
and fatigability of the ocular, bulbar and limb muscles. On examination she has
bilateral ptosis and extra-ocular muscle weakness. Reflexes are preserved, there
is no muscle wasting. The Edrophonium test is positive.
In this patient
a)
Thymectomy has no long term benefit
b)
If a thymoma is present the muscle weakness would improve
c)
In non-thymoma patients improvement will be seen in 60 % of patients
d)
The prognosis is worse as the patient is under 40 years of age
e)
Thymectomy should not be performed if the patient has positive receptor
antibodies
Answer:
c)
In myasthenia gravis thymectomy offers long-term
benefits. It improves the prognosis in patients below 40 years, in those with
positive receptor antibodies and in those who have had the disease for less than
10 years. Following thymectomy 60 % of non-thymoma patients will improve. In
thymoma although surgery is necessary as the tumour is potentially malignant,
the myasthenia is unlikely to improve.
Revision Tip
Revise myasthenia gravis KEYS to
SUCCESS in Medicine page 478-480
