Hemiparkinsonism-hemiatrophy syndrome: clinical and radiologic features

Hemiparkinsonism-hemiatrophy syndrome is parkinsonian symptoms limited to half the body, with atrophy on the same side of the body or brain atrophy on the opposite side. This rare condition generally begins earlier in life than most forms of parkinsonism. While the syndrome was defined on the basis of purely clinical symptoms, the advent of modern imaging techniques has provided new insights into the pathological picture of hemiparkinsonism-hemiatrophy syndrome. The authors reviewed 11 cases of hemiparkinsonism-hemiatrophy syndrome in 2 women and 9 men. The average age of onset of the syndrome in these patients was 38.1 years; there was no family history of parkinsonism among these patients and only two patients had any history of head trauma. Six of the patients had body hemiatrophy and contralateral (opposite side) brain atrophy, four had only body hemiatrophy, and one patient had only brain hemiatrophy in addition to the hemiparkinsonism. In seven patients the affected side was the dominant side and in four the affected side was nondominant. No correlation could be found between the degrees of brain hemiatrophy and body hemiatrophy. Five of the patients developed bilateral disease as their condition progressed. This observation, which has been made in previous reports of hemiparkinsonism, suggests that both sides of the brain may be affected, but one side has a considerable head start in degenerating. One common hypothesis of the etiology of hemiparkinsonism-hemiatrophy is that the condition arises from perinatal asphyxia (insufficient oxygenation in the period shortly before to shortly after birth). It is not easy, however, to explain the long delay between the initial brain insult and the development of symptoms. One possibility, however, is that the perinatal insult carries the brain close to the edge of parkinsonian symptoms. It is known that significant destruction of neurons in the substantia nigra must take place before parkinsonian symptoms appear. If the perinatal insult comes close to the threshold, then a slight loss of neurons, which would be uneventful in a normal individual, might carry these patients over the threshold and result in neurological symptoms. (Consumer Summary produced by Reliance Medical Information, Inc.)