muscular dystrophy is an autosomal dominant condition
usually evident in the fifth decade of life. It is
characterised by ptosis with progressive involvement
of extraocular muscles until total paralysis of eye
movements results. The pupillary reactions are spared.
Flaccid dysphagia, flaccid dysarthria, facial weakness
and proximal limb weakness are late features. Investigations
reveal an elevated creatine phosphokinase - up to
five times - and characteristic muscle biopsy - "rimmed"
vacuoles in a proportion of muscle fibres. Treatment
is supportive. Dysphagia may require nasogastric feeding.
Death usually results from infection. It must be distinguished
from myasthenia gravis and mitochondrial myopathy
in which ptosis is also a distinctive feature.