Reversible cerebral perfusion alterations in children with transient mutism after posterior fossa surgery

Abstract

Mutism is an infrequent and transitory complication observed following posterior fossa surgery. Patients become mute in the immediate postoperative period, with restoration of speech within a few weeks in the absence of additional neurological alterations. The anatomical structures thought to be involved are the connections between the cerebellar dentate nucleus, the ventrolateral nucleus of the contralateral thalamus and the supplementary motor area. In an attempt to understand the pathophysiology of this syndrome, and to depict the perfusion of different brain areas semiquantitatively, in two children who had become mute after posterior fossa surgery we performed a Tc99M-HM-PAO SPECT study during the period of mutism and again when normal speech had returned. In one patient, who had a left cerebellar astrocytoma, the SPECT study showed a marked reduction of cerebral perfusion in the right fronto-parietal region, and in the other, who had a medulloblastoma, a left fronto-temporo-parietal perfusion alteration was observed. When the patients regained normal speech, the follow-up SPECT studies revealed normalization of the cerebral perfusion. This study demonstrates the occurrence of a focal dysfunction of cerebral perfusion in children with cerebellar mutism after posterior fossa surgery. These observations are useful in extending our understanding of the pathophysiology of this postoperative clinical syndrome.

Cerebellocerebral Diaschisis and Postsurgical Posterior Fossa Syndrome in Pediatric Patients

“…We fully agree that the study of Miller et al 1 adds important evidence to current insights in the possible cause and pathophysiologic mechanism underlying the PFS, but we would like to point out that CCD has already been reported on several previous occasions as a possible explanation for transient postoperative mutism 2,3 and for the constellation of neurobehavioral and affective symptoms characterizing PFS in the pediatric population. [4][5][6] For instance, Mariën et al (2001Mariën et al ( , 2003 4,6 reported the preliminary results of a prospective study in which the pathophysiologic role of CCD in PFS was explored.…”

Cerebellar mutism

“…63 Multiple studies have supported the theory of cerebellocerebral diaschisis using different imaging techniques that revealed decreased blood flow, metabolic action, and function within supratentorial structures that play a crucial role in speech production, such as the thalami, inferior frontal gyrus, and temporal lobe. 26,34,63,65,83 In almost every case the abnormal findings returned to normal when mutism resolved.…”

Supratentorial Arterial Ischemic Stroke following Cerebellar Tumor Resection in Two Children

“…Also in case studies of children with PFS after cerebellar tumor surgery, bilateral reduction of supratentorial cerebral perfusion was found [9,10,11]. Reduction of cerebral perfusion is believed to be induced by a usually transient perturbation of the dentato-thalamic-cortical pathways [8].…”

“…Characteristically the impairments recede after days to months. MRI does not explain the anatomical basis of neurologic deficits of PFS, but single photon emission computed tomography (SPECT) findings suggest a transient perturbation of the dentato-thalamo-cortical pathways, resulting in a diminished or altered function of supratentorial brain structures [8,9,10,11]. …”