[Peculiar involuntary movements in premature babies with specific cerebellar injuries]

We observed characteristic involuntary movements in premature babies during early infancy. These movements consisted of asymmetrical irregular banging of the extremities, similar to chorea, ballisms, or jitteriness. We investigated the clinical characteristics and neuroimaging findings of the patients with these peculiar involuntary movements to clarify their pathophysiological mechanisms and to find a treatment. In our sequential follow-up study on 90 premature infants with various pre-and perinatal brain insults, we found various types of cerebellar injuries in 28 patients. In 19 of these, the prominent injuries were observed in the inferior cerebellar hemispheres. These cerebellar injuries were often observed in patients born before the gestational age of 27 weeks. Fourteen of the 28 patients with cerebellar injuries displayed the above-mentioned characteristic involuntary movements. Twelve of these 14 patients with both cerebellar injury and involuntary movements were born before the gestational age of 27 weeks. On the contrary, 10 patients with cerebellar injury born after the gestational age of 27 weeks did not display these peculiar involuntary movements. It is noteworthy that cerebral injuries were not associated with the occurrence of these involuntary movements. Two patients with asymmetrical cerebellar deformity caused by compression due to a cystic lesion did not show these involuntary movements. The movements appeared around the corrected age of 3 months, and they disturbed the patients' acquisition of sitting ability. Nine patients with these involuntary movements developed severe athetotic cerebral palsy. These movements showed drug resistance, however, benzodiazepines had a partial effect in some patients. Recently, cerebellar injury in premature infants has received a lot of attention. We believe that the peculiar involuntary movements we observed in the present patient group may be caused by a particular type of cerebellar damage specific to premature infants born before 27 weeks of gestational age.