Metachromatic leukodystrophy (MLD) is a lysosomal storage disease which is commonly listed in the family of leukodystrophies as well as among the sphingolipidoses as it affects the metabolism of sphingolipids. Leukodystrophies affect the growth and/or development of myelin, the fatty covering which acts as an insulator around nerve fibers throughout the central and peripheral nervous systems. MLD involves cerebroside sulfate accumulation. Metachromatic leukodystrophy, like most enzyme deficiencies, has an autosomal recessive inheritance pattern. Signs and symptoms
Like many other genetic disorders that affect lipid metabolism, there are several forms of MLD, which are late infantile, juvenile, and adult. In the late infantile form, which is the most common form of MLD (50–60%), affected children begin having difficulty walking after the first year of life, usually at 15–24 months. Symptoms include muscle wasting and weakness, muscle rigidity, developmental delays, progressive loss of vision leading to blindness, convulsions, impaired swallowing, paralysis, and dementia. Children may become comatose. Untreated, most children with this form of MLD die by age 5, often much sooner. Children with the juvenile form of MLD (onset between 3 and 10 years of age) usually begin with impaired school performance, mental deterioration, and dementia, then develop symptoms similar to the late infantile form but with slower progression. Age of death is variable, but normally within 10 to 15 years of symptom onset. Some patients can live for several decades after onset. A recent trend is to try to distinguish early-juvenile (ages 3–7) and late-juvenile forms of the disease.
These adverse effects are believed to be due to the neurotoxic effects of repeated withdrawal from alcohol on aberrant neuronal plasticity and cortical damage. Repeated periods of acute intoxication followed by acute detoxification has profound effects on the brain and is associated with an increased risk of seizures as well as cognitive deficits. The effects on the brain are similar to those seen in alcoholics who have detoxified repeatedly but not as severe as in alcoholics who have no history of prior detox. Thus, the acute withdrawal syndrome appears to be the most important factor in causing damage or impairment to brain function. The brain regions most sensitive to harm from binge drinking are the amygdala and prefrontal cortex.People in adolescence who experience repeated withdrawals from binge drinking show impairments of long-term nonverbal memory. Alcoholics who have had two or more alcohol withdrawals show more frontal lobe cognitive dysfunction than those who have experienced one or no prior withdrawals. Kindling of neurons is the proposed cause of withdrawal-related cognitive damage. Kindling from repeated withdrawals leads to accumulating neuroadaptive changes. Kindling may also be the reason for cognitive damage seen in binge drinkers. Diagnosis
Many hospitals use the Clinical Institute Withdrawal Assessment for Alcohol (CIWA) protocol in order to assess the level of withdrawal present and therefore the amount of medication needed. When overuse of alcohol is suspected but drinking history is unclear, testing for elevated values of carbohydrate-deficient transferrin or gammaglutamyl transferase can help make the diagnosis of alcohol overuse and dependence more clear.