What is Lou Gehrig Disease?
Amyotrophic lateral sclerosis (ALS), also referred to as Lou Gehrigs disease, is a form of motor neuron disease caused by the degeneration of neurons located in the ventral horn of the spinal cord and the cortical neurons that provide their afferent input. The condition is often called Lou Gehrig's disease in North America, after the famous New York Yankees baseball player who was diagnosed with the disease in 1939. The disorder is characterized by rapidly progressive weakness, muscle atrophy and fasciculations, spasticity, dysarthria, dysphagia, and respiratory compromise. Sensory function generally is spared, as is autonomic, and oculomotor activity. ALS is a progressive, fatal, neurodegenerative disease with most affected patients dying of respiratory compromise and pneumonia after 2 to 3 years; although some perish within a year from the onset of symptoms, and occasional individuals have a more indolent course and survive for many years.
The disorder causes muscle weakness and atrophy throughout the body caused by degeneration of the upper and lower motor neurons. Unable to function, the muscles weaken and atrophy. Affected individuals may ultimately lose the ability to initiate and control all voluntary movement, although bladder and bowel sphincters and the muscles responsible for eye movement are usually, but not always, spared.
Cognitive function is generally spared for most patients although some (~5%) also have frontotemporal dementia. A higher proportion of patients (~30-50%) also have more subtle cognitive changes which may go unnoticed but are revealed by detailed neuropsychological testing. Sensory nerves and the autonomic nervous system, which controls functions like sweating, are generally unaffected but may be involved for some patients.
The earliest symptoms of ALS are typically obvious weakness and/or muscle atrophy. Other presenting symptoms include muscle twitching, cramping, or stiffness of affected muscles; muscle weakness affecting an arm or a leg; and/or slurred and nasal speech. The parts of the body affected by early symptoms of ALS depend on which motor neurons in the body are damaged first. About 75% of people contracting the disease experience limb onset ALS i.e. first symptoms in the arms or legs. Patients with the leg onset form may experience awkwardness when walking or running or notice that they are tripping or stumbling, often with a "dropped foot" which drags gently along the ground. Arm-onset patients may experience difficulty with tasks requiring manual dexterity such as buttoning a shirt, writing, or turning a key in a lock. Occasionally, the symptoms remain confined to one limb for a long period of time or for the whole length of the illness. About 25% of cases are bulbar onset ALS. These patients first notice difficulty speaking clearly or swallowing. Speech may become slurred, nasal in character, or quieter. Other symptoms include difficulty swallowing, and loss of tongue mobility. A smaller proportion of patients experience respiratory onset ALS where the intercostal muscles that support breathing are affected first.
Regardless of the part of the body first affected by the disease, muscle weakness and atrophy spread to other parts of the body as the disease progresses. Patients experience increasing difficulty moving, swallowing, and speaking or forming wordsS ymptoms of upper motor neuron involvement include tight and stiff muscles and exaggerated reflexes including an overactive gag reflex. An abnormal reflex commonly called Babinski's sign (the big toe extends upward and other toes spread out) also indicates upper motor neuron damage. Symptoms of lower motor neuron degeneration include muscle weakness and atrophy, muscle cramps, and fleeting twitches of muscles that can be seen under the skin. Around 15–45% of patients experience pseudobulbar affect, also known as emotional lability, which consists of uncontrollable laughter, crying or smiling, attributable to degeneration of bulbar upper motor neurons resulting in exaggeration of motor expressions of emotion.
To be diagnosed with ALS, patients must have signs and symptoms of both upper and lower motor neuron damage that cannot be attributed to other causes.
Although the sequence of emerging symptoms and the rate of disease progression vary from person to person, eventually most patients are not able to stand or walk, get in or out of bed on their own, or use their hands and arms. Difficulty swallowing and chewing impair the patient's ability to eat normally and increase the risk of choking or aspirating food/liquids into the lungs. Aspiration pneumonia and weight maintenance can then become a problem. Because the disease usually does not affect cognitive abilities, patients are aware of their progressive loss of function and may become anxious and depressed. A small percentage of patients go on to develop frontotemporal dementia characterized by profound personality changes; this is more common among those with a family history of dementia. A larger proportion of patients experience mild problems with word-generation, attention, or decision-making. Cognitive function may be affected as part of the disease process or could be related to poor breathing at night. Most people with ALS die of respiratory failure or pneumonia. Death usually occurs within two to five years of diagnosis. Although the disease can strike at any age, most people are between forty and seventy years of age when the disease strikes and men are affected slightly more frequently than women. ALS, a progressive disease, leads to death in half of the people diagnosed within three years and ninety percent within six years.
ALS predominantly affects the motor neurons, and in the majority of cases the disease does not impair a patients mind, personality, intelligence, or memory. Nor does it affect a persons ability to see, smell, taste, hear, or feel touch. Control of eye muscles is the most preserved function, although some patients with an extremely long duration of disease (20+ years) may lose eye control too. Unlike multiple sclerosis, bladder and bowel control are usually preserved in ALS, although as a result of immobility and diet changes, intestinal problems such as constipation can require intensive management.
For patients without a family history of the disease, which includes approximately 95% of cases, there is no known cause for ALS.
Adopted from wikipecia.com