Aplasia Axialis Extracorticalis Congenita

APLASIA AXIALIS EXTRACORTICALIS CONGENITA (congenital subcortical underdevelopment of axons), or Pelizaeus-Merzbacher disease (Pelizaeus, Merzbacher), a rare (known in only one family) but thoroughly studied hereditary disease of the nervous system, in which the basis is aplasia of the subcortical white matter of the cerebral hemispheres. Microscopically, the process amounts to the breakdown of myelin, and partly of the axis cylinders themselves, with glial proliferation. The disease is apparently not aplasia in the true sense of the word, but represents a slowly progressive pathological process. Clinically, ataxia, nystagmus, tremor, slow speech, and general slowing of movements, paralysis of trunk muscles, spastic contractures, and progressive dementia were observed.