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The following is a summary of “Long-term outcomes in antibody-negative autoimmune encephalitis: a retrospective study,” published in the September 2024 issue of Neurology by Mangioris et al.

Antibody-negative autoimmune encephalitis (AE) cases represent one-third of suspected patients with AE and lack typical AE features.

Researchers conducted a retrospective study to characterize the clinical phenotypes and long-term outcomes of “possible only” and “probable” AE cases.

They evaluated adult patients of Mayo Clinic’s Autoimmune Neurology Clinic (01/01/2006–12/31/2020), meeting diagnostic criteria for “possible only” or “probable but antibody-negative” AE, with ≥ 1 year of follow-up, who underwent neural antibody testing.

The results showed 45 patients (median age 61 years, female 47%) with “possible only” or “probable” AE were analyzed. A nadir modified Rankin Scale (mRS)  ≥3 was recorded in 91% of patients, where CSF was inflammatory in 45%, and MRI showed encephalitic changes in 47%. Unclassified neural-specific IgG staining was detected in 11%, whereas 2 patients had paraneoplastic causation, and 31% had relapsed. Memory dysfunction (69%), attention deficits (38%), and gait instability (29%) were the most frequent at the last follow-up. Most patients (76%) were independent at the last follow-up, with only 2 requiring assistive devices, and 24% with Poor neurological outcomes (mRS ≥3) were noted. A higher mRS score and gait assistance requirement at 3 months predicted poor outcomes (P ≤0.01).

They concluded that despite significant disability at initial disease stages, most antibody-negative AE patients regain independent functioning. Early functional status and gait assistance requirements may predict long-term prognosis.

Source: link.springer.com/article/10.1007/s00415-024-12680-y