Classic Charcot amyotrophic lateral sclerosis

Abstract

This chapter discusses the neurophysiological aspects of classic Charcot ALS—that is, the progressive loss of both upper and lower motor neurons (LMNs), in the absence of significant sensory, sphincter, or cognitive dysfunction, developing without evidence of structural abnormality in the brain or spinal cord as detected by imaging. Amyotrophic lateral sclerosis (ALS) is the commonest form of the motor neuron diseases and includes classical sporadic Charcot ALS, progressive bulbar palsy, progressive muscular atrophy (PMA), and primary lateral sclerosis. Peripheral motor conduction velocity is normal in ALS and a moderate or marked conduction slowing suggests a different or additional disorder. The type and extent of needle electromyography (EMG) abnormalities is variable in different ALS patients and in different muscles in the same patient. The electrophysiological techniques provide insight into the dysfunctional anterior horn cells in ALS and their central connections. The most promising methods for LMN studies include methods to estimate motor unit numbers, to track the physiology of single motor units over time, and cross-correlation studies of the synchronous firing of motor units. However, there also have been significant advances in the clinical neurophysiology of the upper motor neurons (UMN) in ALS.