ALS is a disease caused by the neurodegeneration,which means the continuous deathof motor neurons.
as ALS acts
By Francisco Rotta
ALS symptoms may change according to the damaged area – upper limbers, lower limbs, respiratory muscle or bulbar muscle (responsible for speech and swallowing) and which neurons are more affect, upper motor neuron or lower motor neuron. Usually the upper motor neuron degeneration causes slowness of movement, muscle stiffness (rigidity) and muscle spasms. On the other hand, the lower motor neuron degeneration leads to flaccidity (decrease muscle tone), atrophy, involuntary twitching of muscle fiber visible over the skin (fasciculation). Since ALS attacks only motor neurons related to voluntary muscle, other organs such as heart, digest system, bladder and sexual organs are not affected. The sense of sight, touch, hearing, cognitive function and eyes movements are also preserved.
At the beginning, the patient usually have located symptoms. They can be in one of the upper limber (most frequent), lower limber, bulbar muscle or respiratory muscle (rarely). When it started in upper limber, is common to see atrophy in hand´s muscle, especially in the triangle between the dumb and index finger. In lower limber is more frequent to see the involvement of the front leg muscle, leading to the inability to lift front part of the foot (foot drop).
There is no specific test to establish the diagnosis of ALS. To diagnose is necessary a careful clinical examination plus some test, such as electromyography, magnetic resonance imaging (MRI) and other laboratory exam that can change according to each patient. Usually doctors try to ruling out other diseases that mimic ALS.
Trying to make easy the diagnosis and ALS treatment, even without the confirmation, the Ministry of Health established, in November 2002, a clinical protocol and therapeutic guideline to ALS through the ordinance no.913. This document, created from El Escorial Criteria World Federation of Neurology, points that:
The ALS clinical diagnosis can be rated in degrees of certainty, according to the presence of upper/lower motor neuron degeneration signs in the same anatomic regions: brainstem (bulbar motor neuron); cervical, thoracic and lumbar levels of spinal cord. The terms “clinically definite” and “clinically probable” describes the level of certainty based in some criteria:
- Clinically definite ALS: Upper and lower motor neuron degeneration signs in three or more regions;
- Clinically probable ALS: Upper and lower motor neuron dysfunction signs in two regions or having upper motor neuron findings anatomically rostal (above) lower motor neuron findings;
- Clinically possible ALS with test support: Upper and lower motor neuron findings in only one region and there is electromyography evidence of lower motor neuron dysfunction in at least two limbs, since the laboratory test and neuroimaging delete other possible diseases.
Natural history of disease
In the course of the disease the symptoms get worse and also new regions of the body will be affected. The progressive degeneration leads to functional incapacity and the patient will need a wheelchair, assistance for personal care, changing in the food consistence, and even the use of tube feeding, nonverbal communication technique and respiratory machine.
The ALS progression is extremely variable for patient to patient. Generally, the life expectancy is 3-5 years after the first symptoms appear. However, 20% of the patients live for at least 5 years and 10% live more than 10 years. It is not clear why some patients have a slow evolution than other. Even though there is not a treatment that can cure or stop the ALS progression, the multidisciplinary intervention (with physician, physiotherapist, occupational therapist, nutritionist, speech therapist, psychologist, social worker) can provide a higher life expectancy and better qualitative of life.