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 an entity that entails a constellation of signs and symptoms which are recorded in a limited number of pediatric patients who have been operated on mainly for tumors involving the posterior cranial fossa, and more precisely, the region of the vermis. Medulloblastoma seems to constitute the most commonly recognized pathological substrate, associated with this entity. The most prevalent constituents of this syndrome are noted to be a, often transient, although protracted, language impairment, emotional lability, along with cerebellar and brainstem dysfunction. Apart from that, a definite proportion of involved individuals are affected by irreversible neurological defects and long-lasting neurocognitive impairment. A bulk of literature and evidence based on clinical trials exist, which reflect the continuous effort of the scientific community to highlight all perspectives of this complex phenomenon. There are several circumstances that intervene in our effort to delineate the divergent parameters that constitute the spectrum of this syndrome. In summary, this is implicated by the fact that inconsistent nomenclature, poorly defined diagnostic criteria, and uncertainty regarding risk factors and etiology are all constituents of a non-well-investigated syndrome. Currently, a preliminary consensus exists about the identification of a group of diagnostic prerequisites that are managed as sine qua non, in our aim to document 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. It is common concept that midline tumor location, diagnosis of medulloblastoma, younger age at diagnosis, and preoperatively established language impairment should be accepted as the most determinant predisposing conditions for the establishment of this syndrome. A well-recognized pathophysiological explanation of CMS includes disruption of the cerebellar outflow tracts, the cerebellar nuclei, and their efferent projections through the superior cerebellar peduncle. Despite the relative advancement that is recorded regarding the diagnostic section of this disease, no corresponding encouraging results are reported, regarding the available treatment options. On the contrary, it is mainly targeted toward the symptomatic relief of the affected individuals. The basic tenet of our review is centered on the presentation of a report that is dedicated to the definition of CMS etiology, diagnosis, risk factors, clinical presentation, and clinical management. Apart from that, an effort is made that attempts to elucidate the paramount priorities of the scientific forum, which are directed toward the expansion 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.

Neuroanatomy of cerebellar mutism syndrome: the role of lesion location

“…This matches the time course of deficits in CMS that are observed acutely but also have been associated with long-term impairments. This cerebro-cerebellar disconnection leads to diaschisis, 29 the interruption of a pattern of brain activity in regions spatially distant from the site of a lesion. It also leads to a developmental diaschisis, with areas of the brain disconnected from the cerebellum developing differently than they would have with an intact cerebro-cerebellar connection.…”

Cerebellar Mutism after posterior fossa tumor surgery: is it predictable, preventable, treatable?

“…Although most studies indicate the occurrence of cerebellar mutism in 25% to 30% of operated cases, it is difficult to estimate the actual incidence because mild cases of postoperative verbal, cognitive or motor impairment may go unnoticed [3]. Although it is a consensus in the literature and in the experience of the services that cerebellar mutism occurs in a minority of cases, the individual repercussions are very impactful and imply prolonged hospital stays [13].…”

“…Although the studies do not have a high level of evidence for the establishment of these strategies, it is necessary to take measures to maintain homeostasis and cerebral protection in order to offer the best conditions for the reestablishment of temporarily impaired neural functions. A fundamental element in this process is rehabilitation involving therapies with a multidisciplinary team, including physical therapy and speech therapy, which must be maintained in the long term to enable the restoration of functionalities [8] [13].…”