A 15-year-old boy developed progressive cerebellar dysfunction over 3 weeks. Examination showed ataxic gait, unsteady tandem gait, horizontal nystagmus, intention tremor, and ataxia on heel-toe-shin testing (Video 1, links.lww.com/WNL/C323). Dysdiadochokinesia and dysarthria were found but not illustrated in the video. Neuroimaging and CSF biochemistry was normal. Serum and CSF metabotropic glutamate receptor type 1 (anti-mGluR1) autoantibodies were found. His cerebellar function improved markedly within 3 months of initiating immunotherapy (Video 1, links.lww.com/WNL/C323). The median age at onset of anti-mGluR1 encephalitis is 55 years.1,2 Paraneoplastic syndromes should be considered, but anti-mGluR1 encephalitis is more often autoimmune in younger patients.1,2
Video 1
Subacute cerebellar dysfunction in adolescent with antimetabotropic glutamate receptor type 1 encephalitis. The video shows our patient with abnormal cerebellar signs including broad-based ataxic gait and unsteady tandem gait, horizontal nystagmus, mild intention tremor with finger-nose testing, and pronounced ataxia on heel-toe-shin testing. This is followed by resolution of the abnormal cerebellar signs after immunotherapy.Download Supplementary Video 1 via http://dx.doi.org/10.1212/201268_Video_1
Study Funding
The authors report no targeted funding.
Disclosure
The authors report no relevant disclosures. Go to Neurology.org/N for full disclosures.
Acknowledgment
The authors would like to acknowledge and thank Dr. Dimple Rajgor for her assistance in formatting, reviewing, and in submitting the manuscript for publication.
Appendix Authors
- Received January 28, 2022.
- Accepted in final form August 3, 2022.
- © 2022 American Academy of Neurology
