Diagnosis of muscular dystrophies : the changing concepts

Detailed analysis of muscle biopsy using histological and enzyme histochemical staining techniques forms the basis of diagnosis of muscular dystrophies, while clinical features and family history are important adjuncts in categorising the type of dystrophy. However, in a significant proportion of cases having overlapping clinical and histological features, it is not possible to provide accurate diagnosis. These conditions can be grouped as Limb girdle muscular dystrophy (LGMD), Decker muscular dystrophy (BMD), early onset Duchenne muscular dystrophy (DMD), Congenital muscular dystrophy (CMD), Severe childhood autosomal recessive muscular dystrophy (SCARMD), and SCARMD in girls/manifesting DMD carriers. Immunohistochemical staining procedures demonstrating the presence/absence of dystrophin, adhalin and merosin are found to be of immense value in arriving at a conclusive opinion specifying the type of muscular dystrophy. It is also evident that muscular dystrophy in young girls resembling DMD is not uncommon and that these are mostly cases of SCARMD in girls having adhalinopathy. In addition, a significant proportion of patients (9 in the present series) with clinical and histopathological diagnosis of DMD are likely to be cases of SCARMD in boys after immunohistochemical study of muscle biopsies.