Anti-N-methyl-d-aspartate Receptor Encephalitis: A Case Series and Review of the Literature

Anti-N-methyl D-aspartate Receptor Encephalitis in India: A Literature Review

Anti N-methyl D-aspartate receptor encephalitis (NMDAR-E) though rare, is currently considered as the commonest antibody mediated encephalitis in the world. No review on perspectives of NMDAR-E from India is available. The aim of the study was to review all the cases of NMDAR-E reported from India until June 2021 in terms of clinical features, diagnosis, and treatment, and perform a comparison of adult and paediatric cases. A literature review of NMDAR-E case reports/case series published from India till June 2021 was done. Demography, clinical profile, triggers, electroencephalography (EEG), neuroimaging, treatment details and outcomes were analysed. Sixteen case series and 35 case reports with a total of 249 cases were analysed. 82% of cases were from paediatric age group. The female to male ratio was 3:1. Psychiatric deficits, movement disorders, seizures, and language abnormalities were the most common clinical features. MRI brain abnormalities were seen in 45% patients. Electroencephalographic abnormalities were seen in 85% of patients. Infective triggers (herpes simplex virus and various other agents) were reported in 11% of the cases. Pediatric patients as compared with adults had more encephalopathy, autonomic dysfunctions, and normal imaging whereas the latter had more cognitive dysfunctions and delta brush pattern in electroencephalography (p<0.005). Therefore, to conclude, this literature review suggests that overall, the clinical spectrum of Indian cases is like cases described from other parts of the world. However, most reported cases from India belonged to paediatric age group who had more encephalopathy, autonomic dysfunctions, and normal brain imaging compared to adults. A few novel infectious agents as triggers were described from India.

Gray matter atrophy and corresponding impairments in connectivity in patients with anti-N-methyl-D-aspartate receptor encephalitis

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a severe autoimmune disease that is commonly accompanied by cognitive impairment and various neurological and psychiatric symptoms, advanced image analyses help explore the pathogenesis of this disease. Therefore, this study aimed to explore specific structural and functional alterations and their relationship with the clinical symptoms of anti-NMDAR encephalitis. In this study, twenty-two patients with anti-NMDAR encephalitis after the acute stage and 29 controls received cognitive assessments and magnetic resonance imaging. Grey matter atrophy was measured using voxel-based morphometry, and functional alterations in abnormal regions were subsequently investigated using resting state functional connectivity (RSFC). Finally, correlation analyses were performed to explore the associations between imaging alterations and cognitive assessments. The patients demonstrated significant gray matter atrophy in the bilateral triangle part of the inferior frontal gyrus (triIFG.L and triIFG.R) and right precuneus, decreased RSFC between triIFG.L and bilateral Heschl gyrus (HES), decreased RSFC between triIFG.R and HES.R, decreased RSFC between right precuneus and left cerebellum, and increased RSFC between triIFG.R and left superior frontal gyrus. Further correlation analyses showed that the gray matter volume in triIFG.R and decreased RSFC between triIFG.L and HES.R were associated with decreased memory scores, whereas decreased RSFC between triIFG.R and HES.R was marginally correlated with the disease course in patients. In conclusion, this study suggests that cognitive impairments in patients with anti-NMDAR encephalitis may be mainly associated with gray matter atrophy and abnormal RSFC in the triIFG. These findings provide new insights into anti-NMDAR encephalitis pathogenesis and help explore potential treatments.

Progressive cortical and sub-cortical alterations in patients with anti-N-methyl-D-aspartate receptor encephalitis

BACKGROUND

Advanced structural analyses are increasingly being highly valued to uncover pathophysiological understanding of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Therefore, we aimed to explore whether and how antibody-mediated NMDAR dysfunction affected cortical and sub-cortical brain morphology and their relationship with clinical symptoms.

METHODS

We performed surface-based morphometry analyses, hippocampal segmentation, and correlational analyses in 24 patients with anti-NMDAR encephalitis after acute disease stage and 30 normal controls (NC) in this case-control study.

RESULTS

Patients showed significantly decreased cortical alterations mainly in language network (LN) and default mode network (DMN), as well as decreased gray matter volume in left cornu ammonis 1 (CA1) body of hippocampus. Further correlation analyses showed that the decreased cortical thickness in the right superior frontier gyrus was associated with decreased cognitive scores, the decreased cortical volume in the right pars triangulari and decreased surface area in the right pars operculari were associated with decreased memory scores, whereas decreased gray matter volume in the left CA1 body was significantly correlated with longer time between first symptom and imaging in the patients.

CONCLUSION

These results suggested that cognitive impairments resulted from long-term sequelae of the encephalitis were mainly associated with cortical alterations in LN and DMN and sub-cortical atrophy of left CA1 body, which can be served as effective features to assess disease progression in clinical routine examination.

Bortezomib for treatment of anti–NMDA receptor encephalitis in a pediatric patient refractory to conventional therapy

Purpose

The case of a pediatric patient with treatment refractory anti–N-methyl-d-aspartate (NMDA) receptor encephalitis treated with the plasma cell–depleting therapy bortezomib is reported.

Summary

A 5-year-old female presented to the hospital with a 1-week history of altered mental status, agitation, and possible seizure-like activity. She was admitted to the hospital for suspected meningitis or meningoencephalitis and an extensive workup was completed, including sending blood and cerebrospinal fluid (CSF) for testing for NMDA receptor antibodies. While test results were pending, the patient was treated initially with intravenous immunoglobulin (IVIG) for 4 days followed by high-dose methylprednisolone for 5 days. The patient’s serum and CSF studies were positive for NMDA receptor antibodies, confirming the diagnosis of anti–NMDA receptor encephalitis. She was then treated with plasmapheresis therapy every other day for 5 treatments, without any clinical improvement. The patient then received rituximab once weekly for 6 weeks. Three weeks after completion of rituximab therapy, the patient was started on her first cycle of bortezomib therapy. She received a total of 6 cycles, with improvement in her clinical status beginning with the third cycle. Upon completion of 6 cycles, the patient’s mental status and level of functioning had greatly improved. She was discharged to an inpatient rehabilitation facility and ultimately able to return home to her family.

Conclusion

A 5-year-old female with anti–NMDA receptor encephalitis was successfully treated with bortezomib after having shown no clinical improvement during treatment with IVIG, high-dose methylprednisolone, plasmapheresis, and rituximab.

Anti-N-methyl-d-aspartate Receptor Encephalitis Related Sinus Node Dysfunction and the Lock-Step Phenomenon

Described in 2007, anti-N-methyl-d-aspartate receptor encephalitis (ANMDARE) is a rare autoimmune limbic encephalitis affecting young adults (predominantly women of reproductive age) and is a paraneoplastic manifestation of ovarian teratoma in about half of the cases. ANMDARE is characterized by psychiatric changes, neurological changes, autonomic instability and cardiac dysrhythmias. In this report, we present a 36-year-old woman who was 16 weeks pregnant and brought to the hospital with confusion and subsequently had a seizure with Electroencephalography (EEG) demonstrated an extreme delta brush pattern consistent with ANMDARE. Patient developed sinus nodal dysfunction and was also found to have ovarian teratoma, a rather typical presentation for ANMDARE, that is considered a paraneoplastic syndrome for ovarian teratoma. In this report, we highlight the cardiac manifestation of ANMDARE, the pathophysiology associated with autonomic instability, and management strategies of this rare, and largely devastating illness.