Ultrastructural study of neurons in metachromatic leukodystrophy

Neuronal inclusions were investigated with the electron microscope in several regions of the central nervous system (CNS) of a patient with late infantile metachromatic leukodystrophy (MLD). The neuronal perikarya of the spinal anterior horn cells and the neurons in the globus pallidus were distended with concentrically arranged lamellar inclusions which closely resembled membranous cytoplasmic bodies (MCB) of gangliosidoses. Large pyramidal neurons in the motor cortex also contained a few smaller MCB-like inclusions. These neuronal inclusions were relatively uniform in size and in morphology in contrast to pleomorphic inclusions in glial cells in MLD. Membrane-bound vacuoles containing moderately electron-dense granular materials or electron-dense aggregates were found in some pyramidal neurons in the Ammon's horn and cerebellar Purkinje cells. These changes were interpreted to represent the reaction of these neurons to subtle cellular injury which may or may not be related to metabolic derrangement in MLD.