Amyotrophic Lateral Sclerosis

Table of Contents

Amyotrophic Lateral Sclerosis4

Background4

Morphology4

Pathophysiology4

Risk factors5

Etiology5

Epidemiology6

Clinical features6

Tests and Diagnosis7

Treatment of ALS7

Conclusion7

Abstract

The motor neurons of the spinal cord and the brain are the targets of injury in a fairly large number of sporadic and hereditary neurodegenerative disorders, as well as in certain types of infections (e.g. poliomyelitis) and some auto immune diseases. Among the primary neurodegenerative disorders affecting the motor neurons, is the Amyotrophic lateral sclerosis (ALS) or the Lou Gehrig disease. It is also known as the Motor Neuron Disease (MND).

Amyotrophic Lateral Sclerosis

Definition

Amyotrophic lateral sclerosis can be defined as an idiopathic disease which affects the upper and lower motor neurons in the spinal cord, cranial and motor neurons and pyramidal neurons in the motor cortex. It is considered as a progressive degenerative disease of the neurons.The occurrence of this disease affects the working of the voluntary muscles in the body, resulting in progressive muscle weakness, atrophy (amyotrophy) and spasticity. Most cases of ALS are genetic, usually due to the inheritance of an autosomal dominance, accounting for 5% to 10% of such cases. (Rowland LP, Shneider NA, 2001, pp 1688)

Background

Amyotrophic lateral sclerosis (ALS) is one of the most frequent occurring neurodegenerative disorders affecting the motor neurons. This disease was first identified in 1869 by a French neurologist, Jean-Martin Charcot and therefore is sometimes also termed as the Charcot disease.The disease was widely recognized when a famous base-ball player, Lou Gehrig was diagnosed of this disease in 1939.

Morphology

ALS affects both the upper and the lower motor neurons of the pyramidal system. It is characterized by the loss of motor neurons in the anterior horns of the spinal cord, motor nuclei, brain stem and the primary motor cortex of the cerebrum. The overall view of the brain and spinal cord is normal but, in severe cases, the atrophy of the primary motor cortex (placental gyrus) is obvious. The anterior spinal nerve roots are usually found to be atrophic.Cognitive impairment may occur in the patient as a result of the loss of prefrontal neurons. This may include the loss of functional execution but may also cause a change in the behavioral functions of the patient. In other words, it can lead to fronto-temporal dementia. (Armon C. ALS 1996), (Neary D, Snowden JS, Dec. 1998, pp 1546-54)

Pathophysiology

The name ALS characterizes the disease into two; the atrophy of the muscle fibers, which occurs because their responsive nerve cells denervate due to the degeneration of the anterior horn cells in the spinal cord and lateral sclerosis indicates to the hardening of the lateral and anterior columns of the spinal cord. This occurs due to the degeneration of the motor neurons in this area, substituted by fibrous astrocytes or gilosis.

Recent studies show that genetic and sporadic types of ALS may be due to excitotoxicity, resulting in the over triggering of the glutamate receptors, free radical formation, calcium channel autoimmunity or due to the accumulation of neurofilaments inside the cells. Insufficient vascular endothelial growth may also prove to be a contributor in the occurrence of ALS while apoptosis is also an important pathogenic factor, contributing ...