Alexander Disease - Symptoms, Causes and Treatment

Alexander disease is a genetic disorder (also known as leukodystrophies or hyaline pan-neuropathy etc.) of the central nervous system that leads to destruction of myelin sheath. (Myelin is a protective cover made up of fat; its main function is to insulate nerve fibers and help/facilitate rapid transmission of nerve impulses in our brain.)

Just like in case of optical cable lining, if the protective covering is destroyed, signals passing through the optical cable will be lost or will not have proper strength; similarly, in the above disease, wear and tear of the covering myelin causes problems related to nervous system and impairs it. It is a rare but fatal disorder. In this disease, abnormal clumps of protein called Rosenthal fibers are formed in non-neural cells (astrocytes) inside the brain.

Types:

Infantile Alexander Disease: This disorder is found in infants and it progresses to full-fledged disease by the time they are two year old. Life of a child suffering from this disorder is limited to 5 to 10 years and in some cases children die just in a year after birth. The progress of this disorder is characterized by severe mental impairment and spastic quadriparesis. This is the most severe type of disease amongst all.

Juvenile Alexander Disease: It occurs in children from the 5 to 10 years. As the age increases, the onset and progression of this disease becomes slower and hence children suffering from this disorder may live up to 30 to 35 years, before they are completely impaired mentally.

Adult-Onset Alexander Disease: This is the mildest type and the life span of the patient suffering from it is longer than the other two categories. The onset of this disorder can occur in people from age 15 and above, even in old age.

Symptoms: The symptoms at the time of onset of the disorder vary with the age of the patient.

Symptoms of Infantile Alexander disease are:

• This is the most aggressive of the three types of Alexander disease.
• Mental retardation and spastic quadriparesis.
• As the disease progresses, it becomes increasingly difficult to feed and manage the child.
• Brain of the child grows abnormally large (a condition known as megalencephaly) as the brain and nervous system development of the system becomes very slow leading to brain cortex and spinal cord dysfunction.
• Child suffering from this disorder experiences difficulty in walking, speech and also progressive mental deterioration.
• A liquid gets deposited in the area between brain and skull which causes pressure on the brain (also known as hydrocephaly).
• Loss of consciousness

Symptoms of Juvenile Alexander disease are:

• Relatively slow progression of the disease and slower mental deterioration than infantile Alexander disease.
• Weakness and loss of control over limbs, especially legs.
• Difficulty in swallowing and speech.
• Vomiting and ataxia
• Increased sleep disturbance as the disease progresses.
• This disease causes alteration in brain stem as compared to the juvenile type which cause alteration in the brain.

Symptoms of Adult-onset Alexander disease are:

• Slowest progression and mental deterioration in the patient compared to other two types of Alexander disease.
• Difficulty in speech, swallowing and sleep disturbances due to impaired coordination (also known as ataxia).
• Many symptoms of this type of disease match with Juvenile Alexander disease.

Diagnosis and Treatment: Initial diagnosis is based on the symptoms such as mental deterioration, ataxia, enlarged head size etc. As it is also a genetic disorder, the doctor may opt for blood and other tests to confirm the disease. Leukodystrophies, radiologic study and MRI scan are few tests which also can help reveal the existence of this disorder.

Unfortunately, this disorder is incurable and till recent time, there was no alternative treatment to lessen the effects of the disease. However, research in past few years has helped in many issues as the gene related to this disorder has been identified, which makes it possible to make partners aware of situation. The only treatment options available are symptom specific and patient needs to be looked after to make his/her life easier.