Neurological Disorders: Pelizaeus Merzbacher Disease

Pelizaeus Merzbacher disease (PMD) is a type of leukodystrophy.

Leukodystrophies are a group of disorders involving the myelin substance of the brain, spinal cord (together called as central nervous system – CNS) and sometimes of the peripheral nerves as well. For additional details please click on the above link.

There are few different types of PMD including milder to very severe variants. The most severe forms are rapidly progressive and fatal and the milder types although cause neurological disability but may be compatible with life for few to even several decades.

It is a genetic disease and results due to mutation of a gene in the x chromosome. This gene codes for proteolipid protein a constituent of myelin tissue. The mutation of the gene causes abnormality at the level of production of myelin.

This neurodegenerative disorder generally starts manifesting during infancy. There are various neurological manifestations and none of these manifestations are typical for this disease since there are many neurodegenerative diseases that can present similarly. The following are the commonly seen manifestations; abnormal movements of the eyes also called as nystagmus which are fast, rhythmic, involuntary, movements of the eyes and abnormally low muscle tone called as hypotonia. Child also presents with delayed milestones or regression of already acquired milestones. Motor functioning and skills are delayed or never acquired. Speech is affected too. The patient also may manifest with other symptoms like shakings (tremors), poor overall coordination, gait difficulties, and abnormal muscle tone in the muscles called as spasticity. As time passes there are usually some muscle contracture too. Cognitive function is generally affected too.

The diagnostic test employed may include brain MRI scan and genetic tests.

No curative treatment is available for this degenerative nervous system disease so far. This means the management is essentially symptomatic and supportive.

A neurologist (pediatric and/or adult) is commonly involved in the management of patients with Pelizaeus Merzbacher disease.