Researchers at a pediatric multiple sclerosis clinic, the Neurological Institute, Buffalo General Hospital, New York, report six (32%) of 19 patients diagnosed with acute disseminated encephalomyelitis (2005-9) who had protracted speech and language deficits and 3 having cerebellar mutism after follow-up from 6 months to 4 years. One third of the 19 patients had cerebellar symptoms, all under the age of 3 years at presentation. The dentate nucleus was involved in all 6 with cerebellar symptoms, but only 3 had mutism. None showed all of the features of posterior fossa syndrome (cerebellar cognitive affective syndrome), but 2 with most extensive cerebellar involvement had marked emotional lability and behavior disturbance. All 3 patients with mutism continue to exhibit expressive speech, neurocognitive, and behavioral problems. Of 3 children with cerebellar involvement without mutism, 1 has reading and coordination difficulties, and 1 has verbal memory and attention deficits. One patient with neurocognitive deficits at follow-up had MRI evidence of cerebellar atrophy. Quantitative MRI should be considered in patients with acute disseminated encephalomyelitis who have persistent cognitive deficits at follow-up. 
COMMENT. Cerebellar involvement in acute disseminated encephalomyelitis is common but speech and language problems are infrequent and cerebellar mutism is rare. Cerebellar mutism occurs primarily as a complication of posterior fossa tumor resection. Other nonsurgical causes of cerebellar mutism in children include cerebellitis, stroke, cavernous malformation, and hemolytic uremic syndrome. Cerebellar mutism usually presents as a feature of the posterior fossa (cognitive affective) syndrome, with neurobehavioral and personality changes. MRI reveals damage to the dentate nucleus and dentatothalamic tract. The outcome is variable.
Postoperative cerebellar mutism syndrome (CMS): MRI features and origin are reported in 28 children with medulloblastoma treated at Children's National Medical Center, Washington, DC. (Wells EM et al. JNS Peds April 2010;5(4):online; Respond: Roger J Packer MD. E-mail: email@example.com). Preoperative MR images show a significant association with brainstem invasion and a trend toward cerebellomedullary angle involvement. Immediately postoperative images show cerebellar edema in 92%, especially middle and superior cerebellar peduncle edema. At 1 year after surgery, patients with CMS show atrophy/gliosis of total cerebellum, vermis, and brainstem, and cognitive deficits. Mean IQ was 16 points lower in patients with CMS compared with those without. Long-term damage to the cerebellum and poor cognitive outcome are not predicted by immediate postoperative MR imaging.