Two patients with distal muscular dystrophy and autonomic nerve dysfunction

Autonomic dysfunction in muscular dystrophy: a theoretical framework for muscle reflex involvement

Muscular dystrophies are a heterogeneous group of genetically inherited disorders whose most prominent clinical feature is progressive degeneration of skeletal muscle. In several forms of the disease, the function of cardiac muscle is likewise affected. The primary defect in this group of diseases is caused by mutations in myocyte proteins important to cellular structure and/or performance. That being stated, a growing body of evidence suggests that the development of autonomic dysfunction may secondarily contribute to the generation of skeletal and cardio-myopathy in muscular dystrophy. Indeed, abnormalities in the regulation of both sympathetic and parasympathetic nerve activity have been reported in a number of muscular dystrophy variants. However, the mechanisms mediating this autonomic dysfunction remain relatively unknown. An autonomic reflex originating in skeletal muscle, the exercise pressor reflex, is known to contribute significantly to the control of sympathetic and parasympathetic activity when stimulated. Given the skeletal myopathy that develops with muscular dystrophy, it is logical to suggest that the function of this reflex might also be abnormal with the pathogenesis of disease. As such, it may contribute to or exacerbate the autonomic dysfunction that manifests. This possibility along with a basic description of exercise pressor reflex function in health and disease are reviewed. A better understanding of the mechanisms that possibly underlie autonomic dysfunction in muscular dystrophy may not only facilitate further research but could also lead to the identification of new therapeutic targets for the treatment of muscular dystrophy.

Complex regional pain syndrome in childhood: report of three cases

We describe three patients with the limb pain of complex regional pain syndrome (CRPS) in childhood with autonomic nervous system function involvement. Their autonomic nerve abnormality was non-invasively examined by means of laser doppler flowmetry (LDF) and a sympathetic skin response (SSR) test. In one it was resolved with physiotherapy, but the others needed epidural anesthesia for pain control. Though CRPS used to be recognized as a refractory disorder in adults, childhood cases have been found in recent years, generally having a better prognosis than adult ones. However, even in the children, the prognosis or responses to the same therapy vary, and there are progressive and refractory cases. CRPS should be considered as a differential diagnosis of unexplained persistent limb pain even in childhood for early and appropriate management.