[An autopsy case with progressive muscular atrophy: an subtype of lower motor predominant amyotrophic lateral sclerosis].

We report an autopsy case with progressive muscular atrophy of 6 years' duration. The patient was a Japanese woman without any hereditary predisposition to neuropathy. She developed muscle weakness of the upper extremities at 66 years of age, followed by muscle weakness of the lower extremities, fasciculation, and atrophy of the tongue. She died at 72 years of age from fat embolism of the lung. During the clinical course of her illness, neither Babinski sign nor hyperreflexia were present on neurological examination. No respirator support was necessary at any time throughout the clinical course. Neuropathological examinations on autopsy disclosed neuronal loss with gliosis in the hypoglossal nucleus and anterior horns of the spinal cord, but there was no apparent atrophy of the motor cortex or degeneration of the corticospinal tract. No Bunina bodies were detected. Skein-like neuronal cytoplasmic inclusions and glial cytoplasmic inclusions positive for phosphorylated TDP-43 were found in the anterior spinal horn. Grouped muscle fiber atrophy of the tongue indicated neurogenic changes. Based on these clinicopathological findings, our diagnosis for this woman was progressive muscular atrophy, which is defined by progressive degeneration of lower motor neurons. We and other experts believe this represents a lower motor neuron-predominant phenotype of ALS.