Neurological dysfunction associated with postoperative cerebellar mutism

Background and objectives. The postoperative cerebellar mutism syndrome (CM S) is an unique acute postoperative complication characterized by transient decrease in speech output (often mutism), apathy, irritability as well as global cerebellar dysfunction. As much as 25% of patients undergoing a rese ction of a cerebellar or IV ventricular tumor may develop such a syndrome. In this retrospective study we characterize the clinical features of the CM S and explore potential etiologic mechanisms. Methods. We conducted a retrospective analysis of medical records and imagi ng tests of 8 consecutive patients with the CMS identified through the data base of the Children's Hospital and Dana-Farber Cancer Institute, Boston, a nd compared with a control group of 8 unaffected children undergoing a comp arable tumor resection. Results. In contrast to the control group, children in the affected group h ad marked decrease in speech output and comprehension, apathy and lack of i nitiative, inattention, persistent eye closure, flaccid hemiparesis and a s evere global cerebellar dysfunction. Swallowing difficulties and bowel and bladder dysfunction were also observed. The median duration of the syndrome as judged by the persistence of the communication abnormalities was 4 week s. The recovery was near complete with exception for a persistent global ce rebellar dysfunction. A comparison of CT and MRI scans of children in both groups failed to identify distinguishing features. Conclusion. A surgical lesion of the midline cerebellum can cause a complex neurological dysfunction such as the CMS. Thus, we postulate that the cere bellum and its connections function as a 'modulatory system' in control of both motor and non-motor functions, including attention and language.