Cerebellar ataxia is a benign complication that is thought to be due to postinfection demyelination. Resolution occurs within 2 to 4 weeks. It is estimated to occur in 1 in 4000 cases, among those younger than 15 years old. It usually appears within one week of the exanthema but it can appear 21 days after the onset of rash. Ataxia, vomiting, altered speech, fever, vertigo and tremor are common symptoms.
Cerebrospinal fluids demonstrate lymphocytosis and elevated levels of cerebrospinal fluid protein.
Physical examination can reveal decreased level of consciousness, headaches, ataxia, vomiting, altered thought patterns, fever and seizures. The duration of the disease is at least 2 weeks. It begins in late stages of varicella, with vomiting, restlessness, irritability, and progressive decrease in the level of consciousness, associated with progressive cerebral edema. Healing of the cutaneous lesions takes three times longer than in the general population. Patients develop high fever.