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ALS
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States and Canada—Lou Gehrig's disease (LGD), is a rare, terminal neurodegenerative disorder that results in the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction. ALS is the most common form of the broader group of motor neuron diseases. ALS often presents in its early stages with gradual muscle stiffness, twitches, weakness, and wasting. Motor neuron loss typically continues until the abilities to eat, speak, move, and breathe without mechanical support are lost. While only 15% of people with ALS also develop full-blown frontotemporal dementia, an estimated 50% face at least minor changes in thinking and behavior, and a loss of energy, possibly secondary to metabolic dysfunction, is thought to drive a characteristic loss of empathy. Depending on which of the aforementioned symptoms develops first, ALS is classified as limb-onset (begins with weakness in the arms or legs) or bulbar-onset (begins with difficulty in speaking and/or swallowing). Respiratory onset occurs in approximately 1%-3% of cases.
Most cases of ALS (about 90–95%) have no known cause, and are known as sporadic ALS. However, both genetic and environmental factors are believed to be involved. The remaining 5–10% of cases have a genetic cause, often linked to a family history of the disease, and these are known as familial ALS (hereditary). About half of these genetic cases are due to disease-causing variants in one of four specific genes. The diagnosis is based on a person's signs and symptoms, with testing conducted to rule out other potential causes.
There is no known cure for ALS. The goal of treatment is to slow the disease progression and improve symptoms. FDA-approved treatments that slow the progression of ALS include riluzole and edaravone. Non-invasive ventilation may result in both improved quality and length of life. Mechanical ventilation can prolong survival but does not stop disease progression. A feeding tube may help maintain weight and nutrition. Death is usually caused by respiratory failure. The disease can affect people of any age, but usually starts around the age of 60. The average survival from onset to death is two to four years, though this can vary, and about 10% of those affected survive longer than ten years.
Descriptions of the disease date back to at least 1824 by Charles Bell. In 1869, the connection between the symptoms and the underlying neurological problems was first described by French neurologist Jean-Martin Charcot, who in 1874 began using the term amyotrophic lateral sclerosis.
ALS is a motor neuron disease, which is a group of neurological disorders that selectively affect motor neurons, the cells that control voluntary muscles of the body. Related motor neuron diseases, sometimes characterized as ALS variants rather than distinct entities, include primary lateral sclerosis (PLS), progressive muscular atrophy (PMA), progressive bulbar palsy, pseudobulbar palsy, and monomelic amyotrophy (MMA).
As a disease, ALS itself can be classified in a few different ways: by which part of the motor neurons are affected; by the parts of the body first affected; whether it is genetic; and by the age at which it started. Each individual diagnosed with the condition will sit at a unique place at the intersection of these complex and overlapping subtypes, which presents a challenge to diagnosis, understanding, and prognosis.
ALS can be classified by the types of motor neurons that are affected. To successfully control any voluntary muscle in the body, a signal must be sent from the motor cortex in the brain down the upper motor neuron as it travels down the spinal cord. There, it connects via a synapse to the lower motor neuron, which connects to the muscle itself. Damage to either the upper or lower motor neuron, as it makes its way from the brain to the muscle, causes different types of symptoms. Damage to the upper motor neuron typically causes spasticity including stiffness and increased tendon reflexes or clonus, while damage to the lower motor neuron typically causes weakness, muscle atrophy, and fasciculations.
Classical, or classic ALS, involves degeneration to both the upper motor neurons in the brain and the lower motor neurons in the spinal cord. Primary lateral sclerosis (PLS) involves degeneration of primarily the upper motor neurons, and progressive muscular atrophy (PMA) involves primarily the lower motor neurons. There is debate over whether PLS and PMA are separate diseases or simply variants of ALS.
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ALS
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States and Canada—Lou Gehrig's disease (LGD), is a rare, terminal neurodegenerative disorder that results in the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction. ALS is the most common form of the broader group of motor neuron diseases. ALS often presents in its early stages with gradual muscle stiffness, twitches, weakness, and wasting. Motor neuron loss typically continues until the abilities to eat, speak, move, and breathe without mechanical support are lost. While only 15% of people with ALS also develop full-blown frontotemporal dementia, an estimated 50% face at least minor changes in thinking and behavior, and a loss of energy, possibly secondary to metabolic dysfunction, is thought to drive a characteristic loss of empathy. Depending on which of the aforementioned symptoms develops first, ALS is classified as limb-onset (begins with weakness in the arms or legs) or bulbar-onset (begins with difficulty in speaking and/or swallowing). Respiratory onset occurs in approximately 1%-3% of cases.
Most cases of ALS (about 90–95%) have no known cause, and are known as sporadic ALS. However, both genetic and environmental factors are believed to be involved. The remaining 5–10% of cases have a genetic cause, often linked to a family history of the disease, and these are known as familial ALS (hereditary). About half of these genetic cases are due to disease-causing variants in one of four specific genes. The diagnosis is based on a person's signs and symptoms, with testing conducted to rule out other potential causes.
There is no known cure for ALS. The goal of treatment is to slow the disease progression and improve symptoms. FDA-approved treatments that slow the progression of ALS include riluzole and edaravone. Non-invasive ventilation may result in both improved quality and length of life. Mechanical ventilation can prolong survival but does not stop disease progression. A feeding tube may help maintain weight and nutrition. Death is usually caused by respiratory failure. The disease can affect people of any age, but usually starts around the age of 60. The average survival from onset to death is two to four years, though this can vary, and about 10% of those affected survive longer than ten years.
Descriptions of the disease date back to at least 1824 by Charles Bell. In 1869, the connection between the symptoms and the underlying neurological problems was first described by French neurologist Jean-Martin Charcot, who in 1874 began using the term amyotrophic lateral sclerosis.
ALS is a motor neuron disease, which is a group of neurological disorders that selectively affect motor neurons, the cells that control voluntary muscles of the body. Related motor neuron diseases, sometimes characterized as ALS variants rather than distinct entities, include primary lateral sclerosis (PLS), progressive muscular atrophy (PMA), progressive bulbar palsy, pseudobulbar palsy, and monomelic amyotrophy (MMA).
As a disease, ALS itself can be classified in a few different ways: by which part of the motor neurons are affected; by the parts of the body first affected; whether it is genetic; and by the age at which it started. Each individual diagnosed with the condition will sit at a unique place at the intersection of these complex and overlapping subtypes, which presents a challenge to diagnosis, understanding, and prognosis.
ALS can be classified by the types of motor neurons that are affected. To successfully control any voluntary muscle in the body, a signal must be sent from the motor cortex in the brain down the upper motor neuron as it travels down the spinal cord. There, it connects via a synapse to the lower motor neuron, which connects to the muscle itself. Damage to either the upper or lower motor neuron, as it makes its way from the brain to the muscle, causes different types of symptoms. Damage to the upper motor neuron typically causes spasticity including stiffness and increased tendon reflexes or clonus, while damage to the lower motor neuron typically causes weakness, muscle atrophy, and fasciculations.
Classical, or classic ALS, involves degeneration to both the upper motor neurons in the brain and the lower motor neurons in the spinal cord. Primary lateral sclerosis (PLS) involves degeneration of primarily the upper motor neurons, and progressive muscular atrophy (PMA) involves primarily the lower motor neurons. There is debate over whether PLS and PMA are separate diseases or simply variants of ALS.