Two children, a girl aged 5 years and a boy aged 11 years, with acute cerebellitis, tonsillar herniation and hydrocephalus are reported from Schneider Children's Medical Center of Israel, Petah Tikva, Tel Aviv. The 5-year old presented with vomiting, occipital pain, and right torticollis of 1 week's duration. Two weeks previously, she had cough and rhinorrhea. Neurological examination revealed hyperactive reflexes, truncal ataxia, and dysmetria. MRI showed diffuse edema (hyperintensity on T2-weighted images) of the right cerebellar hemisphere and vermis, compression of 4th ventricle and brainstem, tonsillar herniation, compatible with cerebellitis. Serology for Mycoplasma pneumoniae was immunoglobulin M-positive and G-negative. Following treatment with dexamethasone, diuretics and vibramycin, signs resolved after 1 week. Follow-up MRI after 7 weeks showed regression of cerebellar edema, correction of cerebellar tonsils, and normal ventricles. The 11-year-old boy recovered after ventriculostomy; the cause for his cerebellitis was unknown. 
COMMENT. Fulminant cerebellitis, a fatal, clinically isolated syndrome, is reported in a 9-year-old boy treated at Jawaharlal Nehru Medical College, Belgaum, India . He presented with severe occipital headache, vomiting, and ataxic gait, associated with intermittent fever. Neurological examination showed a conscious, oriented, irritable child with papilledema, bilateral lateral rectus palsy, brisk reflexes, neck retraction and ataxia. CT head scan revealed hydrocephalus secondary to 4th ventricle obstruction. MRI after ventricular shunt showed bilateral cerebellar swelling and brainstem compression secondary to cerebellitis. PCR studies for herpes simplex virus and varicella were negative. Despite methylprednisolone and shunt, the patient died on day 2 of admission. Posterior fossa decompression was refused.
Cerebellitis, an inflammatory process, is caused by primary infectious, postinfectious, or postvaccination disorder. The authors cite varicella zoster, Epstein-Barr virus, measles, pertussis, diphtheria, Coxsackie, mumps, herpes simplex virus 1, and parvovirus as most frequently involved infectious agents.