TN 3 (02-10)
DI 23022.440 Leigh's Disease
Leigh Necrotizing Encephalopathy; Leigh's Syndrome; Necrotizing Encephalomyelopathy of Leigh's; SNE; Subacute Necrotizing Encephalopathy
Leigh's disease is a rare inherited neurometabolic disorder that affects the central nervous system. This progressive disorder begins in infants between the ages of three months and two years. Leigh's disease can be caused by mutations in mitochondrial DNA or by deficiencies of an enzyme called pyruvate dehydrogenase. Genetic mutations in mitochondrial DNA interfere with the energy sources that run cells in an area of the brain that plays a role in motor movements. There is also a form of Leigh’s disease called X-linked Leigh’s disease which is the result of mutations in a gene that produces another group of substances that are important for cell metabolism. This gene is only found on the X chromosome. Symptoms of Leigh's disease usually progress rapidly. The earliest signs may be poor sucking ability, and the loss of head control and motor skills. These symptoms may be accompanied by loss of appetite, vomiting, irritability, continuous crying, and seizures. As the disorder progresses, symptoms may also include generalized weakness, lack of muscle tone, and episodes of lactic acidosis, which can lead to impairment of respiratory and kidney function.
TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING
Genetic testing for specific mitochondrial or nuclear DNA mutations
ICD-9: 330.8 Other specified cerebral degenerations in childhood
ONSET AND PROGRESSION
The prognosis for children with Leigh's disease is poor. Children who lack mitochrondrial complex IV activity and those with pyruvate dehydrogenase deficiency tend to have the worst prognosis and die within a few years. Those with partial deficiencies have a better prognosis, and may live to be 6 or 7 years of age. Some have survived to their mid-teenage years.
The most common treatment for Leigh's disease is thiamine or Vitamin B1. Oral sodium bicarbonate or sodium citrate may also be prescribed to manage lactic acidosis. Researchers are currently testing dichloroacetate to establish its effectiveness in treating lactic acidosis. In children who have the X-linked form of Leigh’s disease, a high-fat, low-carbohydrate diet may be recommended.
SUGGESTED PROGRAMMATIC ASSESSMENT*
Suggested MER for Evaluation: Clinical examination describing physical findings, family history, muscle biopsy, genetic testing, electromyography or nerve conduction tests, and blood enzyme tests.
Suggested Listings for Evaluation:
Leigh’s disease produces long term interference with age appropriate activities resulting in extreme limitations in functioning.
| || |
* Adjudicators may, at their discretion, use the Medical Evidence of Record or Listings suggested to evaluate the claim. However, the decision to allow or deny the claim rests with the adjudicator.