Three cases of acute encephalopathy with biphasic seizures and late reduced diffusion predominantly manifesting generalized involuntary movements in the chronic phase.

Background: Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) usually has a favorable gross motor prognosis, and involuntary movements that occur after AESD are transient, typically resolving spontaneously during the recovery phase.

Case presentation: Three male patients without any underlying disease or history of perinatal insults developed AESD between 10 and 12 months of age. Case 1 remained choreoathetosis, dystonia, and ataxia, with the choreoathetosis resolving six years after onset. By age 10, he could sit without support and crawl but could not walk independently due to ataxia. Case 2 exhibited persistent athetosis in all four limbs and the trunk. He could not sit without support and required full assistance for movement at age 8. Case 3 displayed athetosis in all four limbs at age 4. He could sit without support and crawl but was unable to walk independently. All patients regained their ability to consume food orally but had severe intellectual disability. Case 1 and 2 developed mild scoliosis. Abnormal findings were observed in the basal ganglia or thalami on magnetic resonance imaging (MRI) or single-photon emission computed tomography (SPECT) scans during acute or subacute phase for all patients.

Discussion: We reported three patients with gross motor dysfunction caused by persistent involuntary movements, deviating from the usual clinical progression of AESD. In cases where MRI or SPECT revealed basal ganglia abnormalities, it is crucial to consider the possibility of late involuntary movements, and to plan suitable rehabilitation and environmental modifications to alleviate motor dysfunction and scoliosis.