What is Fibrinoid Leukodystrophy?
Fibrinoid Leukodystrophy which is also known by the name of Alexander Disease is an extremely rare but potentially fatal disorder of the brain in which there is extremely low production of myelin which is an outer layer that protects the nerve fibers which results in the nerve fibers getting exposed affecting their ability to transmit signals to and from the brain normally.
Previously, only infants and young children were given this diagnosis but with the advancement of medical technology this disease has been found to occur in individuals among all age groups.
The deficit in myelin production in individuals with Fibrinoid Leukodystrophy is seen in the cerebrum in majority of the cases, although in some cases the white matter may not be severely affected due to Fibrinoid Leukodystrophy especially in patients who develop this disease at a much later stage in life.
The primary presenting feature in almost all the cases of Fibrinoid Leukodystrophy is the presence of Rosenthal Fibers in certain areas of the brain and spinal cord which almost clinches the diagnosis of Fibrinoid Leukodystrophy.
What are the Causes of Fibrinoid Leukodystrophy?
Majority of the cases of Fibrinoid Leukodystrophy is caused due to mutation in gene GFAP. This gene encodes a protein called glial fibrillary acidic protein which is found in the astrocytes within the central nervous system.
This follows an autosomal dominant pattern of inheritance meaning that one copy of the faulty gene is enough for a child or an individual to develop Fibrinoid Leukodystrophy. In some cases, a de novo mutation can also cause Fibrinoid Leukodystrophy.
In some cases the cause of the condition is not known but the mutation is believed to occur during embryonic development causing the child to have Fibrinoid Leukodystrophy.
What are the Symptoms of Fibrinoid Leukodystrophy?
Fibrinoid Leukodystrophy was previously subdivided into three forms which were the infantile, juvenile, and adult but now it is divided into two subdivisions which are type I and type II.
The type I form of Fibrinoid Leukodystrophy occurs in children with onset of symptoms by the age of 4 and type II with symptom onset at any age in life after the age of 4.
For type I form of Fibrinoid Leukodystrophy, the symptoms include failure to thrive, developmental delays, behavioral abnormalities, psychomotor impairment, and seizures. Additionally, the child may show macrocephaly, excessive muscle stiffness, ataxia, dysphagia, problems with breathing and talking.
For type II Fibrinoid Leukodystrophy, there will be regression of development, adult onset seizures, and gradual mental decline in some cases. Gait ataxia may also be seen in some individuals with type II Fibrinoid Leukodystrophy.
How is Fibrinoid Leukodystrophy Diagnosed?
In the previous times, the presence of Rosenthal Fibers in the brain was clear cut evidence that the patient was suffering from Fibrinoid Leukodystrophy but that theory has been put to rest as there are many other brain and neurological disorders where there is presence of Rosenthal Fibers on brain biopsy.
As of now, MRI evidence is taken for the diagnosis of type I Fibrinoid Leukodystrophy in which the MRI will show clear damage to the white matter but this test is not so positive for type II Fibrinoid Leukodystrophy as in such cases there is little to no change in the white matter of the brain even though there may be changes seen in the cerebellum and brainstem.
The best way to diagnose this condition is through a genetic test which will clearly show mutation in GFAP gene which will virtually confirm the diagnosis of Fibrinoid Leukodystrophy.
How is Fibrinoid Leukodystrophy Treated?
The treatment for Fibrinoid Leukodystrophy is symptomatic and supportive. Seizures can be treated by anticonvulsants. Walking aids may be useful for individuals with ambulatory dysfunction. Apart from this, the treatment is purely supportive for patients with Fibrinoid Leukodystrophy.