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Clinical features of anti-mGluR5 encephalitis and comparison according to MRI positivity: a systematic review and
Jihong Han1, Xiaofang Zhong2, Lei Liu3
1Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China.
Background:
Anti-metabotropic glutamate receptor 5 (mGluR5) encephalitis is a rare autoimmune neurological disorder with high clinical heterogeneity. The phenotypic spectrum of anti-mGluR5 autoimmune encephalitis (AE) and the relationship between MRI findings and clinical presentations remain to be fully elucidated.
Methods:
Previously reported cases were systematically identified through a literature search of PubMed/MEDLINE, Web of Science and Scopus following PRISMA guidelines. Clinical data from eligible cases, including one from our center, were extracted and analyzed. Patients with a predominant encephalitic phenotype were further stratified into MRI-negative and MRI-positive groups, and statistical comparisons were performed.
Results:
60 patients were identified, including 40 patients with a predominant AE phenotype. Among the anti-mGluR5 AE patients, common manifestations included cognitive deficits, behavioral and mood disturbances, sleep disturbances, seizures, movement disorders and decreased level of consciousness (dLOC). Tumors occurred in 25.0% of patients, with a higher frequency in Western than Chinese patients (60.0% vs. 4.0%; p <0.001). Brain MRI abnormalities were observed in 52.5% patients, and no significant differences in mRS was observed between MRI-positive and MRI-negative patients. Cerebrospinal fluid (CSF) positivity for anti-mGluR5 antibodies was lower than serum positivity (54.8% vs. 96.8%; p < 0.001). Exploratory analyses suggested cognitive deficits tended to be more frequent in MRI-positive than MRI-negative patients (95.2% vs. 68.4%; p = 0.040). CSF pleocytosis was relatively more common in the MRI-positive group, while sleep disturbances, seizures, dLOC, prodromal symptoms, CSF Oligoclonal bands (OCBs) tended to occur more frequently in the MRI-negative group, though not statistically significant.
Conclusions:
The clinical features of anti-mGluR5 AE are heterogeneous. Chinese patients show lower tumor association. Serum antibody testing may be prioritized over CSF testing for diagnosis in suspected anti-mGluR5 patients. MRI abnormalities are observed in approximately half of patients and may not correlate with mRS. Cognitive deficits tend to be more frequent in MRI-positive patients; whereas several other manifestations showed trends, without reaching statistical significance. These observations may suggest hypothesis-generating patterns warranting confirmation.
Insights
Anti-metabotropic glutamate receptor 5 (mGluR5) encephalitis presents heterogeneously, with cognitive deficits more common in MRI-positive cases. Serum antibody testing is recommended over CSF for diagnosing this autoimmune neurological disorder.
Area of Science:
- Neurology
- Immunology
- Neuroscience
Background:
- Anti-metabotropic glutamate receptor 5 (mGluR5) encephalitis is a rare autoimmune neurological disorder.
- Clinical heterogeneity and the relationship between MRI findings and clinical presentations require further elucidation.
Purpose of the Study:
- To investigate the phenotypic spectrum of anti-mGluR5 autoimmune encephalitis (AE).
- To explore the association between MRI findings and clinical presentations in anti-mGluR5 AE patients.
Main Methods:
- Systematic literature search of PubMed/MEDLINE, Web of Science, and Scopus following PRISMA guidelines.
- Extraction and analysis of clinical data from 60 identified patients, including 40 with predominant AE phenotype.
- Stratification of patients into MRI-negative and MRI-positive groups for statistical comparison.
Main Results:
- Common manifestations include cognitive deficits, behavioral disturbances, seizures, and decreased level of consciousness.
- Tumors occurred in 25% of patients, with higher frequency in Western vs. Chinese patients (60% vs. 4%).
- MRI abnormalities were found in 52.5% of patients; cognitive deficits were more frequent in MRI-positive cases (95.2% vs. 68.4%).
- Serum anti-mGluR5 antibody positivity (96.8%) was higher than CSF positivity (54.8%).
Conclusions:
- Anti-mGluR5 AE exhibits heterogeneous clinical features, with lower tumor association in Chinese patients.
- Serum antibody testing is suggested over CSF testing for suspected anti-mGluR5 AE diagnosis.
- MRI findings may correlate with cognitive deficits, but not necessarily with functional outcome (mRS).
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