Visual Impairments in Anti-NMDAR Encephalitis Undetectable With OCT

Among patients with anti-N-methyl-D-aspartate (NMDA) receptor (NMDAR) encephalitis, no visual systems seemed to be involved despite visual dysfunction, according to findings published in the Journal of Neuro-Ophthalmology.

Researchers retrospectively analyzed 32 eyes of 16 patients with anti-NMDAR encephalitis (81% women; mean age, 30.6 years; 56% White ethnicity) and 64 eyes of 32 patients who served as healthy controls (81% women; mean age, 30 years; 56% White ethnicity). Patients underwent visual acuity testing, optical coherence tomography (OCT), and 18-fluorodeoxyglucose (FDG) positron emission tomography (PET) computed tomography (CT) scans. Potential effects on visual systems were evaluated and compared between patients and controls.

Among the patients, 38% had a new cancer diagnosis and the modified Rankin Scale (mRS) score was 2 or less among 81%.

At visual acuity assessment, patients with anti-NMDAR encephalitis differed significantly from those in the control group for letter acuity at 2.5% contrast (β, -4.4; 95% CI, -8.5 to -0.3; P =.037) and at 1.25% contrast (β, -6.8; 95% CI, -12.0 to -1.7; P =.010).

No significant differences in OCT measures were observed between the groups.

At FDG-PET/CT a median 26 days after symptom onset, patients had median Z-scores of -2.7 in the lateral occipital lobe, -2.5 in the visual cortex, -1.0 in the parietal lobe, -1.1 in the temporal lobe, -1.4 in the frontal lobe, -1.0 in the caudate, and -0.0 in the cerebellum. Altogether, 71% had hypometabolism in the occipital lobe.

No significant correlations were observed for FDG-PET/CT Z-scores and visual acuity among patients.

The major limitation of this study was that only 7 patients underwent FDG-PET/CT.

“Anti-NMDAR patients exhibit visual dysfunction without structural retinal damage. Although occipital hypometabolism could explain visual dysfunction in patients with anti-NMDAR encephalitis, we did not find such an association when comparing acute-phase occipital metabolism with postacute visual acuity and OCT,” the researchers report. “Future prospective studies with the addition of acute-phase OCT and visual acuity assessment (if possible), postacute FDG-PET/CT assessments at time of postacute OCT and VA assessment, electroretinography, and visual evoked potentials may further clarify visual dysfunction in anti-NMDAR encephalitis.”

Disclosure: Multiple study authors declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.