REVERSIBLE CEREBRAL PERFUSION ALTERATIONS IN CHILDREN WITH TRANSIENT MUTISM AFTER POSTERIOR-FOSSA SURGERY

Mutism is an infrequent and transitory complication observed following posterior fossa surgery. Patients become mute in the immediate postop erative period, with restoration of speech within a few weeks in the a bsence of additional neurological alterations. The anatomical structur es thought to be involved are the connections between the cerebellar d entate nucleus, the ventrolateral nucleus of the contralateral thalamu s and the supplementary motor area. In an attempt to understand the pa thophysiology of this syndrome, and to depict the perfusion of differe nt brain areas semiquantitatively, in two children who had become mute after posterior fossa surgery we performed a Tc99M-HX4-PAO SPECT stud y during the period of mutism and again when normal speech had returne d. In one patient, who had a left cerebellar astrocytoma, the SPECT st udy showed a marked reduction of cerebral perfusion in the right front o-parietal region, and in the other, who had a medulloblastoma, a left fronto-temporo-parietal perfusion alteration was observed. When the p atients regained normal speech, the follow-up SPECT studies revealed n ormalization of the cerebral perfusion. This study demonstrates the oc currence of a focal dysfunction of cerebral perfusion in children with cerebellar mutism after posterior fossa surgery. These observations a re useful in extending our understanding of the pathophysiology of thi s postoperative clinical syndrome.