3.1. Introduction
The hereditary anterior horn cell diseases most often affect children. In the past, infectious poliomyelitis was seen throughout the Western World, but now is limited to parts of the third word.
The major anterior horn cell spectrum that confronts adult clinicians is that of late onset spinal muscular atrophies, adolescent Kugelberg–Welander disease, overlaps with amyotrophic lateral sclerosis and metabolic variants of storage and degenerative disease that affect anterior horn cells. The primary example of the latter is hexosaminidase A deficiency. The exciting new aspects of this old differential diagnosis are autoimmune forms of anterior horn cell and axonopathies such as GMI neuropathy and those neuropathies with conduction block that appear to be lower motor neuron in origin but are treatable. Unfortunately, most often the adult clinician will be faced with various forms of amyotrophic lateral sclerosis to diagnose.
There are many variants of both ALS and anterior horn cell disease that complicate hereditary degenerative diseases that must be differentiated for genetic counseling and prognosis. Autoimmune attack on both motor axons, their terminal twigs and anterior horn cells themselves are now routinely sought and are an early hopeful sign for the future treatment of these diseases.
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