CEREBELLITIS

Cerebellitis is an inflammatory process characterized by an acute or subacute onset of cerebellar ataxia following an infection, in general of viral origin. The primary infection occurs usually at the level of the gastrointestinal tract or the respiratory airways (Cohen and Lipton, 1990 Klockgether et al., 1993). Ataxia may also appear after the skin rash of an exanthematous infection or after a vaccination.

Most frequently, cerebellitis is observed in children aged one to six years and in young adults, although ataxia may also develop in the elderly. In children, it is estimated that about 0.05–0.10% of all children with varicella infection present cerebellar ataxia. Cerebellitis in young adults affects males more than female, with a M/F ratio varying from 2:1 up to 4.3 :1. In some series, a marked predominance of males has been observed (Klockgether et al., 1993).

Clinical presentation

Body temperature is not a reliable clinical sign, and fever may have completely disappeared at the time of neurological presentation (Cleary et al., 1980). Ataxia appears within several hours, several days or develops slowly over a period of one to four weeks. The cerebellar syndrome is isolated or appears as part of a diffuse inflammatory complication in the brain (Table 16.1). In children, the most frequent picture is an association of sudden limb clumsiness and gait unsteadiness with muscle hypotonia. Overall, limb ataxia is accompanied in 75% of cases by oculomotor disturbances. Figure 16.1A illustrates the cerebellar signs observed during the acute stage in a series including nine patients aged 12 to 64 presenting cerebellitis in the absence of clinical evidence of extracerebellar involvement. Relative frequencies of different types of oculomotor deficits are shown in Fig. 16.1B.