Chapter 188: ALS and Other Motor Neuron Diseases

Amyotrophic lateral sclerosis (ALS) is the most common form of progressive motor neuron disease (Table 188-1). ALS is caused by degeneration of motor neurons at all levels of the CNS, including anterior horns of the spinal cord, brainstem motor nuclei, and motor cortex. Familial ALS (FALS) represents 5–10% of the total and is inherited usually as an autosomal dominant disorder.

TABLE 188-1: Sporadic Motor Neuron Diseases
CHRONICENTITY
Upper and lower motor neuronAmyotrophic lateral sclerosis
Predominantly upper motor neuronPrimary lateral sclerosis
Predominantly lower motor neuronMultifocal motor neuropathy with conduction block
 Motor neuropathy with paraproteinemia or cancer
 Motor predominant peripheral neuropathies
Other 
Associated with other neurodegenerative disorders 
Secondary motor neuron disorders (see Table 188-2) 
Acute 
Poliomyelitis 
Herpes zoster 
Coxsackie virus 
West Nile virus 

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