97 - Disorders of Upper and Lower Motor Neurons

Abstract

The term "motor neuron disease" was initially coined to refer to a specific disorder of both upper motor neurons (UMNs) and lower motor neurons (LMNs), otherwise known as amyotrophic lateral sclerosis. The term motor neuron diseases however encompasses a broader family of disorders which may affect these neurons. We review in this chapter the causes, diagnosis and treatment of the motor neuron diseases according to whether the disorder affects UMNs, LMNs or both UMNs and LMNs. The neuroanatomy, clinical features and laboratory evidence of UMN and LMN disorders are discussed. Specific UMN diseases are then described including primary lateral sclerosis, hereditary spastic paraplegia and the human T-lymphotropic virus-associated myelopathies. Diseases of LMNs are then addressed including poliomyelitis and other viral acute flaccid paralyses and the sequela of post-polio syndrome, benign focal amyotrophy, spinal muscular atrophy, Kennedy disease and progressive muscular atrophy. Finally the pathogenesis, etiology, clinical features, diagnosis, prognosis and treatment of amyotrophic lateral sclerosis are discussed in detail along with other diseases which affect both UMNs and LMNs.