MR Imaging Findings in Anti-Leucine-Rich Glioma Inactivated Protein 1 Encephalitis: A Systematic Review and Meta-analysis.

BACKGROUND: Antibodies against leucine-rich glioma inactivated protein 1 (LGI1) constitute a common form of autoimmune encephalitis. On MR imaging, it may show T2 FLAIR hyperintensities of the medial temporal lobe (T2 FLAIR-MTL), involve the basal ganglia, or be unremarkable. PURPOSE: We performed a systematic review and meta-analysis to obtain prevalence estimates of abnormal findings on MR imaging in anti-LGI1 encephalitis. A human brain map of the LGI1 microarray gene expression was derived from the Allen Human Brain Atlas. DATA SOURCES: PubMed and Web of Science were searched with the terms "LGI1" and "encephalitis" from inception to April 7, 2022. STUDY SELECTION: Thirty-one research publications, encompassing case series and retrospective cohort and case-control studies, with >10 patients with anti-LGI1 encephalitis and MR imaging data were included. DATA ANALYSIS: Pooled prevalence estimates were calculated using Freeman-Tukey double-arcsine transformation. Meta-analysis used DerSimonian and Laird random effects models. DATA SYNTHESIS: Of 1318 patients in 30 studies, T2 FLAIR-MTL hyperintensities were present in 54% (95% CI, 0.48-0.60; I2 = 76%). Of 394 patients in 13 studies, 27% showed bilateral (95% CI, 0.19-0.36; I2 = 71%) and 24% unilateral T2 FLAIR-MTL abnormalities (95% CI, 0.17-0.32; I2 = 61%). Of 612 patients in 15 studies, basal ganglia abnormalities were present in 10% (95% CI, 0.06-0.15; I2 = 67%). LGI1 expression was highest in the amygdala, hippocampus, and caudate nucleus. LIMITATIONS: Only part of the spectrum of MR imaging abnormalities in anti-LGI1 encephalitis could be included in a meta-analysis. MR imaging findings were not the main outcomes in most studies, limiting available information. I2 values ranged from 62% to 76%, representing moderate-to-large heterogeneity. CONCLUSIONS: T2 FLAIR-MTL hyperintensities were present in around one-half of patients with anti-LGI1. The prevalence of unilateral and bilateral presentations was similar, suggesting unilaterality should raise the suspicion of this disease in the appropriate clinical context. Around 10% of patients showed basal ganglia abnormalities, indicating that special attention should be given to this region. LGI1 regional expression coincided with the most frequently reported abnormal findings on MR imaging. Regional specificity might be partially determined by expression levels of the target protein.

Inflammatory Optic Neuropathy as a Presenting Feature of Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy.

Background: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is commonly associated with early-onset stroke, migraine and vascular dementia. However, optic nerve involvement has been previously recognised. Results: We report a case of a 21-year-old female presenting with right inferior temporal scotoma, dyschromatopsia, relative pupillary afferent defect and bilateral disk oedema in the fundoscopic examination. Visual evoked potential latencies were bilaterally increased, suggesting optic neuropathy. Cerebrospinal fluid (CSF) evaluation showed 11 leukocytes, .45 mg/dL proteins, elevated IgG (4.55 mg/dL) and 2 oligoclonal bands (OCB) restricted to the CSF. ESR was 17 mm/h and CRP 5 mg/dL. Anti-Aquaporin4 anti-MOG antibodies were negative. The MRI showed right optic nerve hyperintensity, enhancing after the administration of contrast product, and multiple FLAIR focal lesions present throughout the white matter, with a noticeable confluence in the anterior temporal horns. She improved after IV high-dose methylprednisolone. Because the lesions of the white matter were highly atypical for an inflammatory disease and highly suggestive of CADASIL genetic testing was requested. A heterozygous pathogenic variant c994C>T p (Arg332Cys) in the exon 6 of the NOTCH3 gene, compatible with the diagnosis of CADASIL was found. Conclusions: This case highlights isolated optic nerve involvement as a presenting feature of CADASIL, possibly reflecting an inflammatory process associated with this hereditary vasculopathy.

Spasmodic cough preceding CANVAS phenotype in a family with biallelic repeat expansions in RFC1.

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a late-onset, multisystem ataxia that remained only clinically defined, until recently, when the discovery of biallelic repeat expansion in the RFC1 gene allowed the genetic link. We describe the first Portuguese familial CANVAS harboring the pathogenic RFC1 expansion. Detail clinical features and course of four affected members are provided. Phenotype characterizations are important as the novel RFC1 mutation is expected to be a major cause of idiopathic late-onset ataxia.