A group of disorders in which there is degeneration of the nerves in the central nervous system that control muscular activity. This causes weakness and wasting of the muscles. The cause is unknown. The most common type of motor neuron disease is amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease). It usually affects people over the age of 50 and is more common in men. Some cases run in families. Usually, symptoms start with weakness in the hands and arms or legs, and muscle wasting. There may be irregular muscle contractions, and muscle cramps or stiffness. All four extremities are soon affected. Progressive muscular atrophy and progressive bulbar palsy both start with patterns of muscle weakness different from ALS but usually develop into ALS. There are 2 types of motor neuron disease that first appear in childhood or adolescence. In most cases, these conditions are inherited. Werdnig–Hoffman disease affects infants at birth or soon afterwards. In almost all cases, progressive muscle weakness leads to death within several years. Chronic spinal muscular atrophy begins in childhood or adolescence, causing progressive weakness but not always serious disability. There are no specific tests for motor neuron disease. Diagnosis is based on careful clinical examination by a neurologist. Tests including EMG, muscle biopsy, blood tests, myelography, CT scanning, or MRI may be performed. The disease typically goes on to affect the muscles involved in breathing and swallowing, leading to death within 2–4 years. However, about 10 per cent of sufferers survive for 10 years. Nerve degeneration cannot be slowed down, but physiotherapy and the use of various aids may help to reduce disability. The drug riluzole is used to extend life (or the time until mechanical ventilation is required).
Motor neuron disease |
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