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
Footnotes
Go to Neurology.org/N for full disclosures.
Submitted and externally peer reviewed. The handling editor was Whitley Aamodt, MD, MPH.
Teaching slides links.lww.com/WNL/C322
- Received January 28, 2022.
- Accepted in final form August 3, 2022.
- © 2022 American Academy of Neurology
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