Onset is within the first 6 months of life and distinguished by developmental arrest, psychomotor retardation, hypotonia, seizures, and megalencephaly. Poor head and neck control are the results of both the hypotonia and large head. By 12 months of age, the hypotonia gives way to spasticity and episodic decorticate posturing. Death often occurs prior to 4 years of age. The juvenile form exhibits ataxia, tremor, and mental deterioration.
Progression involves signs of dysarthria, dementia, and spasticity.
No megalencephaly is found in this form of the disease. Both neonatal and juvenile forms are thought to have spontaneous mutations. The child came to autopsy following severe dehydration secondary to prolonged vomiting and diarrhea. Hypertrophied fibrillary astrocytes were found throughout the white matter. The infantile form is the most severe of the three.