The Entity of Cerebellar Mutism Syndrome: A Narrative Review Centered on the Etiology, Diagnostics, Prevention, and Therapeutic Options

Abstract

Cerebellar mutism syndrome (CMS), also known as posterior fossa syndrome, is encountered in a subset of children who have undergone an operative procedure of the posterior cranial fossa, mainly involving the vermis, and the most frequent underlying pathology is proved to be medulloblastoma. The most common characteristics of this syndrome include an often transient, although protracted, language impairment, emotional lability, along with cerebellar, and brainstem dysfunction. Nevertheless, a significant number of patients experience persistent neurological deficits and lasting neurocognitive impairment. A lot of research and clinical studies have been performed in order to better delineate this syndrome. The main obstacles in our way to highlight all aspects of this syndrome were related with an inconsistent nomenclature, poorly defined diagnostic criteria, and uncertainty surrounding risk factors and etiology. Currently, there is a combination of diagnostic criteria that are regarded as prerequisites in order to establish the diagnosis of CMS. These include language impairment and emotional lability, as proposed by the international Board of the Posterior Fossa Society in their consensus statement. Several risk factors are recognized as implicated in the pathogenesis of this syndrome, including midline tumor location, diagnosis of medulloblastoma, younger age at diagnosis, and preoperatively established language impairment. A proposed etiology of CMS includes disruption of the cerebellar outflow tracts, the cerebellar nuclei, and their efferent projections through the superior cerebellar peduncle. Specific treatment for CMS is lacking, and it continues to be directed at symptom management. Our aim is to present a comprehensive narrative review of CMS etiology, diagnosis, risk factors, clinical presentation, and clinical management. Moreover, we attempt to recognize the most widely recognized priorities of the research community in order to expand our knowledge in the era of diagnostics, prevention, and therapeutic options for patients suffering from CM, or who are at risk for development of this syndrome.

Postoperative pediatric cerebellar mutism syndrome: A literature review

“…This discrepancy can be partially explained by two factors: first, the telovelar approach requires greater technical skill, and is therefore practiced by experienced surgeons; and second, the transvermian approach is preferred in the presence of large tumors, a well-established risk factor, introducing an additional bias. In fact, in another prospective study, surgery in a low-volume surgery center were found to increase the likelihood of CMS [5,8,10].…”

“…Preoperative language impairment has also been implicated. More precisely, 28.5% of children suffering from preoperative language impairment and developed cerebellar mutism postoperatively [10].…”

“…Walker et al introduced a score model to predict the risk and included six relevant factors. These included primary tumor location, as it was specified by MRI, bilateral middle cerebellar peduncle involvement (invasion and/or compression), dentate nucleus invasion, and age at surgery > 12.4 years [10].…”

“…For both functional areas, broad connectivity to supratentorial structures via the cerebellar peduncles was confirmed. The widespread connectivity and topography of the human cerebellum with cerebral areas have been implicated in non-motor functions [10,12].…”

“…Even though there seems to be convincing evidence for bilateral frontal perfusion deficits in POPCMS patients compared to non-POPCMS patients [15], the included article does not fully support the hypothesis of cerebello-cerebral diaschisis as a pathophysiological explanation of the syndrome for not including preoperative exams Mutism itself is inherently related to supratentorial dysfunction, mediated by crossed cerebello-cerebral diaschisis. Some reports correlate behavioral disturbances in the pediatric population with cerebellar mutism with frontal cortex dysfunction [10]. Some authors have proposed that cerebellar mutism is actually a supratentorial disorder, caused by hypoactivity in the cerebral hemispheres due to disruption of its connections [16].…”