Amyotrophic lateral sclerosis
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Summary
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease causing a progressive loss of motor neurons. The disease prevalence is 5-9 per 100 000. The revised Airlie House criteria define four categories of certainty in making the diagnosis: clinically definite ALS; clinically probable ALS; probable, laboratory-supported ALS and possible ALS. These criteria are mainly based on the number of regions in the central nervous system (bulbar, cervical, thoracic, lumbosacral) affected by upper motor neuron (UMN) and lower motor neuron (LMN) symptoms. Age at disease onset varies widely, but peak incidence is between 40 and 60 years. In about two-thirds of the patients ALS begins with usually asymmetric limb involvement (muscle weakness and wasting). Bulbar onset (dysarthria and dysphagia) is observed in about one-third of the patients. The disease is relentlessly progressive with increasing disability and handicap and leads generally to death resulting from respiratory failure in approximately 3-5 years. The diagnosis is mainly clinical. Ancillary investigations (electrophysiological, neuroimaging and laboratory studies) are used to exclude other diseases. To date, ALS is an incurable disease, but Riluzole has been proven to increase survival. Symptomatic management include rehabilitation therapy, respiratory assistance, antispasticity agents. The etiology is likely multifactorial, involving both genetic and environmental factors. Motor neuron death is believed to arise from mutations in superoxide dismutase I gene (SODI) on chromosome 21. Abnormal neurofilament metabolism, glutamate transporter dysfunction, mitochondrial dysfunction and altered responses to growth factors may play a role. Familial ALS (FALS) accounts for 5-10% of cases, and mutations in SODI are present in 15-20% of families with FALS. *Author: Dr M. van der Graaff (September 2004)*.
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Update : 15/04/2007
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