Cerebellar mutism is linked to midbrain volatility and desynchronization from speech cortices.

This article focuses on the functional brain changes associated with cerebellar mutism syndrome (CMS), a postoperative disorder of speech, movement, and affect occurring after medulloblastoma tumor removal in the posterior fossa. Using functional MRI data from 124 medulloblastoma patients, including 45 with CMS, the study identifies acute hyperactivity and disrupted connectivity of the periaqueductal grey area (PAG)—a midbrain region implicated in vocalization control—with cortical speech motor areas such as Broca's area and medial frontal cortex. These PAG dysfunctions were transient, resolving alongside speech recovery, while broader persistent cortical hyperconnectivity, particularly involving limbic structures like the amygdalae and motor planning areas, was observed and related to cerebellar outflow tract damage. The findings support the hypothesis that disruption of cerebello-PAG circuits contributes to the transient mutism in CMS, whereas intact cerebellocortical pathways may underlie chronic neurocognitive sequelae.