Acute hemiplegia syndrome in childhood.

Three types of clinical features at the onset are well known to be characteristic of acute hemiplegia syndrome (AHS). Type 1 comprises status epilepticus of hemiconvulsions with fever. Representative diseases of this type are the infectious diseases of the central nervous system, acute encephalopathy and cerebral vascular diseases. Type 2 comprises status epilepticus of hemiconvulsions without fever. Cerebral vascular diseases and epilepsy are the major ones of this type. Type 3 comprises hemiplegia or hemiparesis of sudden onset without fever or convulsions. Most patients with this type had cerebral vascular diseases, about half of which were moyamoya disease in Japan. Recent progress in neuroimaging studies has allowed considerable elucidation of the etiology of AHS. Gadolinium-enhanced MRI showed minimal lesions such as capsular infarction more clearly than plain MRI. Acetazolamide test 99mTc-HMPAO SPECT imaging is one of the useful assisted diagnostic techniques for moyamoya disease, because it reveals the reserve capacity of the collaterals. [123I]IMP SPECT is useful for the diagnosis and follow-up of acute disseminated encephalomyelitis (ADEM), as the images of the lesions coincide well with the MRI ones. 99mTc-HMPAO SPECT in a case with alternating hemiplegia revealed normoperfusion in the ictal periods. Four cases of AHS are reported here.