Types

• There are two primary categories of PMD: classic and connatal. The types have overlapping symptoms, although their severity differs.
  
  

Classic PMD Symptoms

• Common signs before age one include hypotonia (weak muscle tone), nystagmus (involuntary eye movement) and delayed motor skills like crawling. Nystagmus often disappears subsequently, while ataxia (difficulty balancing and moving), choreiform movements (involuntary jerking) and spasticity (stiff muscles) develop.
  
  

Connatal PMD Symptoms

• More severe, connatal PMD involves ataxia, difficulty feeding, dysarthria (speech problems), spasticity resulting in deformed joints, whistling while breathing, and seizures, all possibly starting in infancy. Intellectual and motor skills are also severely impaired.
  
  

Cause

• Both types of PMD are inherited. They result when a mutation affects the gene responsible for producing the protective protein (proteolipid protein-1) covering that envelops nerve fibers inside the brain.
  
  

Considerations

• There is no cure or standard treatment for PMD, but the condition can be managed to some extent with medications designed to treat movement problems. Patients with severe PMD usually deteriorate until they die, while milder cases can result in a normal life.