Metabolic myopathies

Abstract

In this chapter, we will consider only those inborn errors of glycogen and fatty acid metabolism that cause exclusively or predominantly neuromuscular disorders. Because this is meant to be a practical book, we have subdivided these disorders into two groups according to their typical clinical presentation. Thus, we first consider diseases characterized by dynamic symptoms and then review disorders characterized by static symptoms. Although the mitochondrial myopathies are reviewed in a separate chapter (see Chap. 64), we discuss here some defects of the mitochondrial respiratory chain that are dominated by exercise intolerance, and, sometimes, myoglobinuria. To understand the dynamic versus the static clinical presentation of these disorders, a brief review of muscle metabolism at rest and during exercise is helpful.