Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder, characterised by progressive muscle weakness that can start in limb, axial, bulbar, or respiratory muscles and then generalises relentlessly, causing progressive disability and ultimately death, usually from respiratory failure.

Epidemiology:

• The incidence of ALS is approximately 1-2.6 cases per 100 000 persons annually
• prevalence is approximately 6 cases per 100 000
• The average age of onset of ALS is currently 58-60 years and the average survival from onset to death is 3-4 years.

Aetiology

ALS has a known cause

Changes in the SOD1 gene leads to protein misfolding, reduced ROS (Reactive oxygen species) removal and increased cell damage and death.

In ALS, the loss of motor neurons occurs predominantly at the level of the corticospinal tract (the large Betz cells) and anterior horn cells, leading to thinning of anterior roots and fibre pathways.

Post-mortem and histologically, ALS is Characterised by:

• Gliosis (hypertrophy of glial cells) - Astrocytosis
• Lateral column degeneration
• Muscle atrophy

Risk factors:

• Positive family Hx
• Age >40
• Military service
• Athletes