Twelve children with type 1 herpes simplex encephalitis (3 with relaps
e, 9 without) have been monitored during the past 7 years, Ten of the
children received intravenous infusion of acyclovir (30 mg/kg/day) for
10 days, 1 child who experienced relapse received 15 mg/kg/day, and a
nother relapsed child received no antiviral agents until relapse, Rela
pse occurred 20-36 days after initial onset, All relapsed patients und
erwent another 10 days of acyclovir treatment (30 mg/kg/day), Choreoat
hetosis appeared as the initial sign of relapse followed by rapidly pr
ogressive unresponsiveness in all 3 relapsed patients: in 1 nonrelapse
d patient choreoathetosis occurred during the recovery period, In thes
e 4 patients involuntary movement was remitted within 3 months to 2 ye
ars. One patient with choreoathetosis died of measles pneumonia 4 mont
hs after onset of herpes simplex encephalitis and the surviving 3 were
severely retarded, Although neuroimaging sparing of basal ganglia doe
s not indicate structural and functional normalities, the disturbance
of the neural connection among the basal ganglia and the cerebral cort
ex, which manifested severe damage over frontal, temporal, and parieta
l mantles on CT, may be the source of movement disorders in these pati
ents, We conclude that choreoathetosis may be the first sign of relaps
e of herpes simplex encephalitis in children and may be an indicator o
f poor prognosis, The neuropathogenesis of choreoathetosis requires fu
rther investigation.