Myoclonic encephalopathies in infants [ENCEFALOPATIE MIOCLONICHE NEL PRIMO ANNO DI VITA]

On the basis of chronological, semeiological, etiological criteria and the course, it is possible to distinguish various types of myoclonic encephalopathies that begin in the first year of life. Early myoclonic encephalopathies mostly arise in the neonatal period and in the first 3 mth. They are characterized by almost continuous erratic myoclonias, spasms in flexion or extension, burst suppression type of EEG, and a course towards death or severe cerebral palsies. The classic syndrome of West (spasms in flexion, hypsarrhythmia and mental regression) can be distinguished from the incomplete West syndromes, in which one of the elements of the triad is missing. But this encephalopathy generally is of the same gravity as the classic West syndrome. It often develops into a Lennox-Gastaut syndrome. Dysmetabolic encephalopathies (early ceroid lipofuscinosis or Hagberg-Santavuori disease; GM2 gangliosidosis or Tay-Sachs disease; infantile progressive poliodystrophy of Christensen-Krabbe or Alpers disease) are manifested by hypotonia (which is then transformed into rigidity), mental regression, blindness, non-epileptic and epileptic myoclonia. They end in death. Myoclonic epilepsies with fixed encephalopathy generally are the result of perinatal or postnatal anoxia. There is microcephaly and mental retardation. The myoclonias and the EEG tracings are of the variable type. Particular forms are: the opsoclonic encephalopathy of Kinsbourne and the postanoxic encephalopathy of Lance-Adams.