Neurological Disorders: Leukodystrophy

Leukodystrophy (LD) is the term used for a white matter disease of the CNS (central nervous system – the brain & spinal cord).

Not all white mater diseases can be called as LD, only the ones associated with a faulty production of white matter, and also the progressive disorders qualify for this term. So MS (multiple sclerosis) a white matter disease of the central nervous system is not an example for LD (explained below).

The white matter disease is nothing but diseases of the myelin. This substance is a complex of fat (lipid) and protein. It forms a microscopic covering around axons of the CNS and enables very rapid conduction of the nerve impulses from one area to another. So its damage will slow down or sometimes even stop conduction of nerve impulses and result in various neurological manifestations.

In MS already formed myelin is damaged while its production is normal so it is not a LD.

Leukodystrophies are genetically linked diseases and majority of them are inherited from parents. Sometimes a spontaneous genetic mutation can produce the diseases and in that case it is not inherited.

The inheritance varies and may be AR, AD or x linked.

• MLD (Metachromatic-Leukodystrophy)
• ALD (adrenoleukodystrophy)
• Krabbe Globoid Cell-Leukodystrophy
• Canavan Disease
• PMD (Pelizaeus Merzbacher disease)
• Alexander Disease etc

The following are the usual clinical presentation for this group of white mater diseases (for more specific manifestations please refer to individual conditions);

• Regression of milestones: child starts losing previously acquired milestones, from then onwards a downhill course

• Various motor manifestations including difficulty with using the limbs, muscle weakness, stiffness, brisk deep tendon reflexes, babinski sign (up going big toe etc)

• Gait difficulties

• Cognitive dysfunction (dementing illness)

• Visual disturbances

• Hearing difficulties

• Bulbar symptoms (difficulty in swallowing, speech, breathing) etc

In addition to the above there may be unique clinical manifestations that are typical to individual diseases.

Seizures are generally absent, especially in the early stages of the disease.

For the diagnosis & treatment please refer to the individual conditions. A neurologist (pediatric and/or adult) is frequently involved in the care of these patients.