Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease and Motor Neuron Disease (MND), is a progressive neurodegenerative disease that attacks nerve cells called neurons in your brain and spinal cord responsible for controlling voluntary muscles. In ALS, motor neurons die (atrophy) over time, leading to muscle weakness, a loss of muscle mass, and an inability to control movement. With voluntary muscle action progressively affected, people may lose the ability to speak, eat, move and breathe.
ALS onset is usually in middle age; 40-70 with an average age of 55 at the time of diagnosis, although it also occurs in young adults and even in children, as well as in very elderly people. Men are slightly more likely to develop ALS than women. Studies suggest an overall ratio of about 1.2 men to every woman who develops the disorder. Although the life expectancy of a person with ALS averages about two to five years from the time of diagnosis, this disease is variable, and many people can live with the disease for five years and more. More than half of all people with ALS live more than three years after diagnosis. The cause of ALS is largely unknown. Researchers are studying several possible causes of ALS, including gene mutation, chemical imbalance, autoimmune response and protein mishandling.
There are many different types of ALS; these types are differentiated by their signs and symptoms and their genetic cause or lack of clear genetic association. 90-95% of all ALS cases are sporadic, which means it occurs in people with no apparent family history, and generally, develops the condition in their late fifties to early sixties. Familial ALS, which means the disease is inherited, accounts for 5-10% of cases. In this type, there is a 50% chance each offspring will inherit the gene mutation and may develop the disease, and the onset is usually between the late forties and early fifties. Rarely, people with familial ALS develop symptoms in childhood or their teenage years.
These individuals have a rare form of the disorder known as juvenile ALS. The main presentations of ALS include:
- Limb-onset ALS (70-80%) with a combination of upper and lower motor neuron (UMN and LMN) signs in the limbs – foot drop, slapping gait, tripping, stumbling, reduced finger dexterity, cramping, and weakness of hand muscles, wrist drop.
- Bulbar-onset ALS (20-25%), presenting with speech and swallowing difficulties, and with limb features developing later in the course of the disease
- Primary lateral sclerosis (less common) with pure UMN involvement.
- Progressive muscular atrophy, with pure LMN involvement.
About 5,000 people in the United States are diagnosed with ALS each year. Worldwide, this disorder occurs in 2 to 5 per 100,000 individuals. Only a small percentage of cases have a known genetic cause. There is no single diagnostic test for ALS as it is a difficult disease to diagnose. There are some specific criteria for the diagnosis of ALS known as the El Escorial criteria developed in 1990 which involves identifying the combination of UMN and LMN signs in the same body region, with subsequent evidence of disease progression to other regions.
Diagnosis is established by a “rule-out” procedure eliminating other diseases that mimic ALS. The following procedures are involved in coming to a diagnosis:
- Electomyography (EMG) and nerve conduction velocity (NCV)
- Blood and urine studies including high-resolution serum protein electrophoresis, thyroid and parathyroid hormone levels and 24-hour urine collection for heavy metals
- Spinal tap
- X-rays, including magnetic resonance imaging (MRI)
- Myelogram of cervical spine
- Muscle and/or nerve biopsy
A thorough neurological examination Symptomatic treatments remain the cornerstone of management for patients with ALS. Care is a multidisciplinary approach involving physiotherapists, occupational therapists, speech therapists, respiratory physicians, gastroenterologists, and social workers working in collaboration to guide symptomatic management through the course of the disease.
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