ALTERNATE NAMES

Alexander Disease Type I; Alexander Syndrome; Dysmyelogenic Leukodystrophy; Dysmyelogenic Leukodystrophy-Megalobar; Fribrinoid Degeneration of Astrocytes-Infantile Type; Fibrinoid Leukodystrophy-Infantile Type; Hyaline Panneuropathy; Leukodystrophy with Rosenthal Fibers; Megalencephaly with Hyaline Inclusion; Megalencephaly with Hyaline Panneuropathy

DESCRIPTION

Alexander disease (ALX) is one of a group of neurological conditions known as the leukodystrophies, disorders that are the result of abnormalities in myelin, the “white matter” that protects nerve fibers in the brain. ALX is a progressive and usually fatal disease. The destruction of white matter is accompanied by the formation of Rosenthal fibers, which are abnormal clumps of protein that accumulate in non-neuronal cells of the brain called astrocytes. Rosenthal fibers are sometimes found in other disorders, but not in the same amount or area of the brain that are featured in ALX.

ALX is classified into two types, Type I and Type II. Type I, the childhood type is the most common and severe form of the disease.

Type I has an onset during the first two to four years of life. Usually there are both mental and physical developmental delays, followed by the loss of developmental milestones, an abnormal increase in head size, and seizures.

ALX occurs in both males and females, and there are no ethnic, racial, geographic, or cultural/economic differences in its distribution.

DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING

Diagnostic testing: ALX is usually based on:

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  Radiologic studies including MRI, CT scan, or ultrasound;

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  Genetic testing showing mutations in the GFAP gene;

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  Chorionic villus sampling (CVS) or amniocentesis; and

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  Brain biopsy or autopsy may be indicated in select cases if the diagnosis cannot be made through other means.

Physical findings: Some signs and symptoms of ALX may include:

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  Mental and physical developmental delays;

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  Loss of developmental milestones;

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  Abnormal increase in head size (megalencephaly); and

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  Seizures.

ICD-9: 330.0

PROGRESSION

The prognosis for ALX is generally poor. Most children with who have been diagnosed with the childhood form do not survive past the age of 6 years.

TREATMENT

There is no cure for ALX, nor is there a standard course of treatment. Treatment of ALX is symptomatic and supportive, primarily consisting of attention to general care and nutritional needs, antibiotic therapy for infections, and management of associated complications such as anti-epileptic drug therapy for seizures. Surgical interventions, including placement of a feeding tube and/or shunting for hydrocephalus, may also be required.

SUGGESTED PROGRAMMATIC ASSESSMENT*

Suggested MER for Evaluation:

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  Clinical history and examination that describes diagnostic features of the impairment;

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  Results of molecular genetic testing;

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  Detailed, current pediatric and neurological examination;

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  Routine laboratory tests; and

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  MRI findings may be characteristic of ALX.

Suggested Listings of Evaluation:

DETERMINATION

LISTING

REMARKS

Meets

110.08 B

ALX with confirmed molecular genetic testing.

111.17

Equals