2026 American Academy of Neurology Autoimmune Abstract Website

Objective:

To describe the phenotypic spectrum, serum‑predominant seropositivity and treatment response in three patients with anti‑IgLON5 disease.

Background:

IgLON5 is a neuronal cell‑adhesion protein; anti‑IgLON5 disease bridges autoimmunity and neurodegeneration. The hallmark is a distinctive sleep disorder, and IgLON5‑IgG is serum‑predominant. IgLON5 antibody can cause encephalitis that can be treated if diagnosed early.

Design/Methods:

Retrospective review of three consecutive patients; IgLON5‑IgG by cell‑based assay (serum and/or CSF). Patient consent was taken and ethical approval sought.

Results:

Three men (88, 71 and 53 years) presented with a prominent sleep disorder, with behavioural change, cognitive decline, agitation, hallucinations and gait/bulbar features.

Case 1: sleep disturbance, cognitive decline, agitation, minimal hallucinations; IVIG and rituximab; back to baseline cognition by week 4.

Case 2: sleep disturbance, agitation, visual hallucinations; attributed to alcohol cirrhosis (not withdrawal); steroids, IVIG and rituximab; back to baseline by week 6.

Case 3: sleep disturbance, unsteadiness/falls, nocturnal hallucinations; managed as alcohol withdrawal, progressing to respiratory failure requiring intubation; PET‑CT showed stable pulmonary nodules with treated testicular malignancy and previous TB; IVIG then plasma exchange and IV methylprednisolone; very good response, rehabilitation then home at baseline cognition.

MRI was non‑specific in all three and CSF protein, glucose and cells were within normal limits. Serum IgLON5‑IgG was positive in 3/3, CSF in only 1/3. Alcohol comorbidity delayed diagnosis in 2/3. No active malignancy was found. All three improved, recovering from being dependent in all care to discharge home, functioning without any support, and one returned to work; best responses followed earlier or escalated treatment.

Conclusions:

In this small series, a prominent sleep disorder was the consistent clue. Serum testing appeared more sensitive than CSF; a CSF‑only strategy may under‑diagnose, similar to literature. MRI was non‑specific and did not aid diagnosis. Earlier immunotherapy appeared to accompany better outcomes, but n = 3 precludes causal inference; findings are hypothesis‑generating.

Generative AI Usage

Yes, used generative AI in the drafting or editing in this abstract.

Tool, version, and prompt(s) used, as well as area of the abstract affected
The authors used Claude (Sonnet 4.6, Anthropic) and used the prompts "help me fixing the wording and make it clearer" and "can you help me write an abstract to the American Academy of Neurology based on these three case reports" for editing and text generation in the Results section (case descriptions) and all abstract sections (Objective, Background, Conclusions). All clinical content, case data, diagnoses, and medical conclusions were provided by the authors. The AI tool was used solely for language editing and structural formatting. The language and wording were later further edited by the author, mainly the title and abstract.