Amyotrophic Lateral Sclerosis (ALS): Overview

Amyotrophic lateral sclerosis is a disease characterized by damage and death of cells in the brain and spinal cord. As a result, muscle weakness and paralysis (immobility) develop. The manifestations of the disease are gradually increasing. Patients lose the ability to move independently, the activity of the muscles necessary for breathing is disrupted, which leads to the death of patients. 

The causes of the disease are not fully understood. There are several factors that influence the onset of the disease.  These include genetic mutations (changes in genetic material), imbalances of certain chemicals in the nervous system, disorders in the immune system (the system that protects the body from various infections), and others. 

Amyotrophic lateral sclerosis affects the neurons of the motor (motor) fields of the cerebral cortex, as well as the motor neurons of the anterior and lateral horns (columns) of the spinal cord. Thus, the structural zones and sections of the central nervous system that are responsible for muscle tone, regulation, and control of muscle activity in the widest spectrum, from the tension of the powerful muscles of the limbs, back, abdominal wall – to facial, respiratory, articulatory movements, thin finger motor skills, etc.

The First Symptoms and Forms of ALS 

Early symptoms of amyotrophic lateral sclerosis include twitching, muscle cramps and numbness, weakness in the limbs, and difficulty speaking. These disorders are characteristic of many other neurological diseases. Therefore, the diagnosis of amyotrophic lateral sclerosis is difficult – until the disease develops to the stage of muscle atrophy. In the pathogenesis of amyotrophic lateral sclerosis, increased activity of the glutamatergic system plays a key role, while an excess of glutamic acid causes overexcitation and death of neurons. Each fibrillar twitching of the muscle corresponds to the death of one motor neuron in the spinal cord, which means that this part of the muscle loses its innervation, it will no longer be able to contract normally and will atrophy. 

The classification of amyotrophic lateral sclerosis currently includes the following forms: 

• Limb-onset ALS (up to three-quarters of patients) begins, as a rule, with the defeat of one or both legs. Patients feel awkward when walking, ankle stiffness, stumble. Lesions of the upper extremities are less common, and it is difficult to perform normal activities that require the flexibility of the fingers or effort of the hand;
• Bulbar-onset ALS is manifested by difficulty in speech (the patient speaks “through the nose,” poorly controls the volume of speech, later experiences difficulty in swallowing). 

Causes of ALS

The cause of the disease is currently unknown. Although numerous risk factors for the disease have been identified, most of which are largely unsupported by empirical evidence. The most important factors are genetics and exposure to heavy metals or chemicals.

ALS presents two forms of appearance:

1. Sporadic ALS: its occurrence is completely random. No risk factor can be identified.
2. Familial ALS: This is an inherited variant with an autosomal dominant profile. It accounts for 5 to 10% of cases. Because of this, it cannot be considered a hereditary disease.

In the absence of family history, the occurrence of the case is considered sporadic and therefore the patient’s relatives do not pose a greater risk than the rest of the population with the condition. 

Diagnostics of amyotrophic lateral sclerosis

When some of the first symptoms of ALS appear, you should see your doctor, who will refer you to a neurologist if necessary. But even a timely visit to a neurologist ensures that the diagnosis is made as soon as it takes some time to verify the diagnosis. 

The neurologist will be interested in medical history and neurological status:

• Reflexes
• Muscle strength
• Muscle tone
• Coordination

Amyotrophic lateral sclerosis is difficult to diagnose in the early stages since the symptoms are similar to other neurological diseases. The following diagnostic methods are used:

• Electroneuromyography. This method measures electrical potentials in muscles and the conduction of impulses along nerve fibers and muscle. Electroneurography allows you to investigate the conduction along nerve fibers. For this test, electrodes are attached to the skin over the nerve or muscle to be examined. A small electric current is passed through the electrodes and the speed of the pulse is determined.
• MRI. This method uses a powerful magnetic field and allows detailed visualization of various tissues, including nerve ones.
• Blood and urine tests. Laboratory testing of blood and urine samples can help the doctor rule out other possible causes of the symptom.
• Muscle biopsy. If a muscle disorder is suspected, a muscle biopsy may be done. In this procedure, a piece of muscle tissue is taken under local anesthesia. The tissue sample is then sent for examination. 

ALS Treatment

Until now, there is no treatment that could stop or slow down the progression of the pathological process in ALS. Riluzole is the only drug that has shown some effectiveness in this disease, but it can only be taken as directed by a doctor. New treatments for this disease are being researched around the world. 

Despite the lack of effective treatment, all ALS symptoms can be corrected to one degree or another. The most important is the correction of swallowing and breathing disorders since they pose an immediate threat to life.

For the treatment of patients with swallowing disorders, the most often used is the insertion of a gastrostomy tube, a special tube that allows food to be injected directly into the stomach. Less often, a nasogastric tube is inserted or a switch to parenteral nutrition is performed. Providing adequate nutrition is extremely important and, most importantly, helps in ALS treatment. Control of salivation is also of great importance.

They usually use such methods as non-invasive or invasive ventilation of the lungs, diaphragm stimulation to solve breathing problems. It has been shown that ensuring adequate breathing can prolong the life of patients.

Muscle cramps, drooling, pain, depression, and many others problems can be resolved with appropriate symptomatic treatment, including special medications or physical therapy. Psychological support of the patient and his family members is of great importance at all stages of the disease, from the diagnosis to the final stages.

Rehabilitation

Patients with amyotrophic lateral sclerosis need, first of all, motor rehabilitation – exercises aimed at training muscles that are not affected by the disease. The regular exercise aimed at increasing overall physical strength allows the patient to:

• overcome the movement defects that the progression of the disease brings as long as possible;
• maintain muscle tone;
• prevent the development of contractures (limitation of movement in the joints).

In connection with the progression of the disease at a certain stage, habilitation is necessary – measures to adapt to life in the conditions of the disease. The most important role in prolonging the life of ALS patients is played by correct work with breathing and swallowing disorders, prevention of aspiration pneumonia, which, is the main cause of death of ALS patients.