Amyotrophic Lateral Sclerosis (ALS)
Causes and risk factors
- Nearly 10% of ALS cases are familial; the disease is transmitted in an autosomal dominant fashion.
- The copper/zinc super oxide dismutase (SOD) gene is mutated in 10-20% of these familial cases.
- ALS patients have higher levels of glutamate in the serum and spinal fluid.
- Although the primary mechanism of SOD1- mediated neural injury is currently unknown, apoptosis, excitotoxicity, and oxidative stress are thought to play major roles in pathogenesis.
Risk factors
- Hereditary- children’s have a 50-50 chance of developing the disease.
- Most commonly occurs in people between the ages of 40 and 60.
- Before the age of 65, more men than women develop amyotrophic lateral sclerosis.
- Recent studies indicate that people who have served in the military are at higher risk of amyotrophic lateral sclerosis.
- Dietary neurotoxin BMAA is a suspected risk factor in amyotrophic lateral sclerosis
Clinical features
- ALS begins insidiously as weakness, atrophy, or fasciculation’s in 1 or more limbs.
- The manifestations are usually distal but gradually progress to involve the more proximal muscles.
- Fasciculation’s and atrophy of the tongue may be noted.
- Hand weakness or clumsiness.
- Slurring of speech or trouble swallowing
- Respiratory insufficiency is usually a late event.
- Around 15–45% of patients experience pseudo bulbar affect, also known as "emotional liability", which consists of uncontrollable laughter, crying or smiling, attributable to degeneration of bulbar upper motor neurons resulting in exaggeration of motor expressions of emotion.
Signs
Physical examination reveals weakness and atrophy of the intrinsic hand muscles, hyperreflexia with extensor plantar responses, and clonus.
Thigh fasciculation’s are common.
Sensory involvement, if any, is minimal.
Complications
- Respiratory failure
- Dysphagia
- Aspiration pneumonia
- Fronto temporal dementia
- Alzheimer’s disease
Tests and diagnosis
- Electromyogram
- Nerve conduction velocity
- Brain or cervical spine MRI
- Screening for infectious diseases like HIV, HTLV, Lyme disease, syphilis
Treatment
- Riluzole is the first and only medication approved by the Food and Drug Administration for slowing ALS. The drug appears to slow the disease's progression in some people, perhaps by reducing levels of glutamate — a chemical messenger in the brain.
- When the muscles that assist in breathing weaken, use of nocturnal ventilatory assistance (intermittent positive pressure ventilation (IPPV) or bilevel positive airway pressure (BIPAP)) may be used to aid breathing during sleep.
Physical therapy
Gentle, low-impact aerobic exercise such as walking, swimming, and stationary bicycling can strengthen unaffected muscles, improve cardiovascular health, and help patients fight fatigue and depression.
Occupational therapy
An occupational therapist can help you become accustomed to a brace, walker or wheelchair and may be able to suggest devices such as ramps that make it easier for you to get around.
Speech therapy
A speech therapist can help teach techniques to make your speech more clearly understood. Later in the disease, a speech therapist can recommend devices such as speech synthesizers and computers that may help you communicate.
Surgical care
Early consideration for elective tracheostomy should be considered in patients with early signs of respiratory difficulty.
