Epstein-Barr virus (EBV)-associated cerebellar ataxia after surgery for suprasellar tumor

A 26-year-old man who developed ataxia of gait and stance after surgery for a suprasellar tumor (juvenile xanthogranuloma) was referred to our outpatient department (Juntendo Univ.) 18 months after the onset of truncal ataxia. Neurological examinations revealed marked truncal ataxia, dysarthria and gaze-evoked nystagmus towards the left side. He had mild dysmetria in all four extremities and dysdiadochokinesia. MRI of the brain showed marked atrophy of the cerebellar vermis and hemispheres and manifest dilation of the fourth ventricle. Serology revealed high titers (1: 1280) of IgG antibodies against EBV capsid antigen (EBV-VCA), but a negative result for EBV-VCA IgM. Examination of the CSF revealed no cells, a glucose level of 56 mg/dl, and a protein level of 30 mg/dl. The CSF tested negative for oligoclonal bands and myelin basic protein. On ENG, gaze-evoked nystagmus was observed at the primary eye position and during leftward gaze in light, but was intermingled with abnormal eye movements such as saccadic intrusions (square wave jerks, double saccadic pulses) in the dark. Both horizontal and vertical pursuits were deteriorated, with remarkable saccadic pursuit. Horizontal OKN was poorly induced. Both horizontal and vertical saccade tests revealed hypermetria in both directions, followed by postsaccadic ocular drift (glissade). Based on these findings along with the finding of atrophy of the vermis on MRI, we considered that the lesions involved not only the vermis and fastigial nucleus, but also the middle portion of the cerebellum, such as the tonsil, uvula, and a part of cerebellar hemisphere (VII). Although MRI did not reveal any other remarkable findings in the brainstem, several nuclei such as the medial vestibular nucleus, nucleus prepositus hypoglossi, the interstitial nucleus of Cajal, and the cell groups of the paramedian tracts could be also suspected as responsible lesions.