Postoperative cerebellar mutism syndrome following treatment of medulloblastoma: neuroradiographic features and origin.

Object: The origin and long-term outcome of cerebellar mutism syndrome (CMS), a postoperative syndrome of diminished speech, hypotonia, and ataxia that affects approximately 25% of patients with medulloblastoma, is poorly elucidated. The current study was undertaken to determine factors associated with development of CMS, a means to determine its severity or cause, and outcomes of patients with this syndrome.
Methods: The study included 28 children with medulloblastoma who either underwent an operation or were referred to the authors' institution soon after surgery. Eleven (39%) of these children had CMS. The preoperative, immediate postoperative, and 1-year postoperative MR images were reviewed by a neuroradiologist blinded to diagnosis of CMS. The severity of mutism and neurological and neurocognitive outcomes were examined.
Results: Preoperative MR images showed no differences in tumor size, hydrocephalus, or peritumoral edema in patients with and without CMS. An association with brainstem invasion was significant (p < 0.05), and there was a trend toward an association with involvement of the cerebellomedullary angle (p = 0.08). Images obtained immediately postoperatively showed cerebellar edema in 92% of all patients; there were trends for more middle and superior cerebellar peduncle edema in patients with CMS (p = 0.05 and 0.07, respectively). At 1 year postoperatively, patients with CMS showed more moderate to severe atrophy/gliosis of total cerebellum (p < 0.01), vermis (p < 0.01), and brainstem (p < 0.05). Mean IQ was 16 points lower in patients with CMS (IQ = 84.2 +/- 15.8) compared with those without CMS (IQ = 100.4 +/- 17.4), with a trend toward significance (p = 0.07).
Conclusions: This study demonstrates that CMS is associated with postoperative damage to the cerebellum and brainstem, damage not predicted by immediate postoperative MR imaging, and with poorer associated functional outcome.