Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that results in progressive muscular paralysis as a result of degeneration of the motor neurons of the primary motor cortex, corticospinal tracts, brainstem and spinal cord.
The disease usually manifests first on the acres by uncontrollable and painless fasciculations and later by flaccid paralysis. From the small hand and foot muscles, the disease progresses proximally, causing atrophy of the muscle groups on the arms and legs.
Many patients continue to experience extremely painful muscle spasms. In the course of the disease, the clinical picture of flaccid atrophic paresis (second motor neuron damaged) mixes with the picture of spastic paresis (first motor neuron damaged).
Other symptoms include loss of motor neurons, inclusions with ubiquitin in upper motor neurons, inclusions with TDP-43 in degenerative lower motor neurons.
The atrophy of the facial muscles makes the face appear expressionless and sunken.
Finally, in infestation of the caudal cranial nerves, paralysis of the muscles on the tongue, palate, pharynx, and larynx manifest themselves with dysphagia and dysarthria (symptoms of bulbar paralysis). Eventually, these lead to death by lack of aspiration of foreign bodies or suffocation.
Sensitivity, sensory and consciousness are usually maintained during the entire course of the disease. The mean age of onset of ALS is about 60 years. Men are slightly more affected than women. The causes of amyotrophic lateral sclerosis are still unclear.
A typically observable familial accumulation of disease cases indicates a genetic disposition, but other factors such as viral or autoimmune diseases are also discussed. ALS usually causes death from respiratory failure within a few years.