Meningoencephalitis associated with GAD65 autoimmunity

Systematic review: clinical characteristics of anti-N-methyl-D-aspartate receptor encephalitis

Background

The number of reported cases of anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis has gradually increased since its discovery in 2007, while there are no uniform treatment guidelines.

Objective

To summarize the clinical characteristics of patients with anti-NMDAR encephalitis and to analyze the factors affecting the disease prognosis.

Methods

A systematic analysis of medical records was conducted, and PubMed, Embase, and Cochrane Library were searched from January 1, 2011, to December 31, 2021. Data were extracted, analyzed, and recorded in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines.

Results

This study included 472 case reports. Most patients had prodromal symptoms of about 2 weeks, including psychiatric symptoms (53.2%), flu-like symptoms (51.5%), and seizures (23.9%), among others. Poor prognoses were associated with patients who had autonomic instability (p = 0.010), central hypoventilation (p = 0.014), and ICU support (p = 0.002). Patients with a higher age of onset were more likely to develop central hypoventilation (OR 1.024, CI 1.006-1.042, p = 0.009), cognitive impairment (OR 1.023, CI 1.009-1.037, p = 0.001), and memory impairment (OR 1.034, CI 1.017-1.050, p < 0.001), whereas patients with a lower age were more likely to have seizures (OR 0.979, CI 0.965-0.993, p = 0.003). In this study, 97.0% of patients received immunotherapy, with the most commonly used treatment regimen being intravenous methylprednisolone (IVGC) and intravenous immunoglobulin (IVIG). When compared with other treatment regimens, the IVGC+IVIG regimen (p < 0.001) resulted in better prognoses.

Conclusion

When encountering patients with fever, headache, and initial psychiatric symptoms of unknown etiology, clinicians should test their CSF for antibodies to distinguish autoimmune encephalitis. Patients with autonomic instability, central hypoventilation, and ICU support had poorer prognoses. Clinicians should be aware that older patients are more likely to develop central hypoventilation, cognitive impairment, and memory impairment, while younger patients are more likely to develop seizures. The IVGC+IVIG treatment regimen has better prognoses than others. This study includes case reports, which have obvious selection bias, and there are no unified standards to measure the severity of the disease. Therefore, in the future, larger samples and randomized controlled trials are needed to evaluate the efficacy of different treatment regimens.

Concomitant Crohn's Disease and Anti-Glutamic Acid Decarboxylase (GAD)-Associated Autoimmune Encephalitis: A Case Report

Crohn's disease is an inflammatory, autoimmune disorder that predominantly affects the intestines but can also affect extraintestinal organs. Certain neurological conditions, such as autoimmune encephalitis, can develop along with this disease. In this case report, we present a case of anti-glutamic acid decarboxylase (GAD) antibody-associated autoimmune encephalitis that occurred shortly after the diagnosis of Crohn's disease and was unrelated to the treatment and nutritional deficiencies. After a significant weight loss (24 kg) and persistent diarrhea, the patient was diagnosed with Crohn's disease by colonoscopy and biopsy. Within two weeks after the diagnosis, he experienced altered consciousness and memory impairment, followed by a rapid deterioration in consciousness and respiratory distress, leading to intubation and admission to the intensive care unit. His brain MRI revealed asymmetrical diffuse cortical diffusion restrictions, hyperintense signals on fluid-attenuated inversion recovery (FLAIR) sequences, and diffuse pachymeningeal contrast enhancement involving both cingulate gyri, bilateral insular cortices, amygdalae, hippocampi, and the right precuneus. Analysis of cerebrospinal fluid (CSF) revealed a slight elevation of CSF proteins, and the patient tested positive for serum anti-GAD antibodies. The patient responded favorably to a seven-day course of intravenous methylprednisolone, five days of intravenous immunoglobulin (IVIG), and oral corticosteroids. Subsequent treatment consisted of monthly IVIG, azathioprine, and vedolizumab, resulting in no neurologic sequelae except mild amnesia. A follow-up MRI at three months showed a nearly complete disappearance of the lesions. This is the first reported case of anti-GAD-associated encephalitis occurring in the presence of Crohn's disease.