A total of 16 patients were included in the study. The mean age of the patients was 39.4 years (range: 19–83 years), with 62.5% of the patients being female. The most frequent symptoms experienced by the patients were altered consciousness (n=12, 75%), dysarthria (n=9, 56%), ataxia (n=9, 56%), vomiting (n=7, 44%), and fever (n=7, 44%). Less common symptoms included seizures (n=5, 31%) and headaches (n=5, 31%). Most patients (75%, n=12) experienced an acute onset of symptoms within 14 days, with an average duration of 3.8 days (standard deviation of 4.3 days, range 1-13 days). The remaining patients (n=4) had symptom onset after 14 days. All cases of cerebellitis with infectious or post-infectious origins had an acute onset, while 75% of patients who developed subacute onset had paraneoplastic origin. The medical histories of the 16 patients were notable for the following: malignancy (n=3), systemic infection (n=1), immunosuppressant therapy (n=4), autoimmune disorders (n=2), pregnancy (n=1), and no significant medical history (n=6). Lymphopenia and leukocytosis were observed in 4 patients each. CSF pleocytosis (>5 white cell count/μl) was recorded in 2/16. Lumbar puncture (LP) was performed in all but one patient. Elevated protein levels were found in 5/15. OCB positivity was detected in 4/15. Elevated IgG index was present in 3/15. The etiologies of AC in the study population were distributed as follows: paraneoplastic (n=4), postinfectious (n=3), infectious (n=4), unknown (n=4), hemophagocytic lymphohistiocytosis syndrome (HLH) (n=1), and autoimmune (anti-GAD antibody-related) (n=1)
All cases demonstrated bilateral cerebellar involvement, with 14 exhibiting symmetrical and 2 exhibiting asymmetrical involvement. None had unilateral involvement. All but one case showed cerebellar vermis involvement. Cerebellar cortical involvement was observed in all patients. In 11 cases, this involvement was isolated to the cortex, while only 2 cases demonstrated predominant white matter involvement. Four cases had middle cerebellar peduncle involvement (one paraneoplastic, one infectious, one HLH, and one unknown etiology). Signs of increased intracranial pressure secondary to cerebellitis were observed in eight patients (50%), four of whom developed obstructive hydrocephalus. Cerebellar atrophy of varying degrees was present in 9 (3 subtle, 3 mild, 1 moderate, 2 severe) out of 10 patients who underwent follow-up imaging. In these cases, moreover, high intensities were noted in the affected cerebellar cortices on fluid-attenuated inversion recovery (FLAIR) images. The most rapid atrophy developed on the 18th day in a patient with Anti-GAD Ab-associated cerebellitis.
Representative cases are demonstrated in Figure 1-2 and radiological findings are summarized in Table 1.