Anti-KLHL11 Encephalitis and Hearing Symptoms

A newly detailed case of autoimmune encephalitis improved significantly after treatment with a drug called efgartigimod, following a poor response to standard therapies. The case, part of a new report by Lin Han, Ying Li, and Chuan Li, focuses on anti-Kelch-like protein 11 (KLHL11) encephalitis, a condition with major implications for hearing and balance.

The study, published in *Frontiers in Immunology*, demonstrates this condition’s clinical heterogeneity and offers fresh insights into how to manage it when first-line treatments fail. For patients and clinicians in the tinnitus and hyperacusis community, it highlights a rare but important autoimmune cause of auditory symptoms that requires specific diagnostic and treatment strategies.

### A Tale of Two Treatment Responses

The researchers reported two distinct cases. The first involved a 52-year-old woman with serum anti-KLHL11 antibodies at a titer of 1:100. She received intravenous immunoglobulin and low-dose rituximab. Her symptoms resolved completely, and no tumor was found.

The second case proved more complex. A 65-year-old man presented with a much higher serum antibody titer of 1:320, with antibodies also present in his cerebrospinal fluid. He received high-dose steroid pulses and the same low-dose rituximab regimen. His improvement was only temporary; symptoms returned within a month.

This contrast led the authors to a preliminary observation: a high serum anti-KLHL11 antibody titer may predict a less robust response to initial immunotherapy. “This association requires validation in larger cohorts,” they caution, but it provides a potential clinical marker for anticipating a more difficult treatment course.

### Efgartigimod: A New Path for Treatment-Resistant Cases

Faced with the returning symptoms in the second patient, the clinical team tried a different approach. They administered efgartigimod, a medication designed to reduce pathogenic antibodies by blocking the neonatal Fc receptor. The result was a marked clinical improvement.

Efgartigimod’s mechanism—directly lowering antibody levels—makes it a logical choice for antibody-driven autoimmune conditions. The authors conclude it “appears to be a promising therapeutic option for paraneoplastic neurological syndrome,” especially when conventional immunosuppression is insufficient. This aligns with a broader search for tinnitus treatments inspired by neurodegenerative disease research, where modulating immune function in the nervous system is a growing area of interest.

### The Critical Link to Cancer and Auditory Symptoms

Anti-KLHL11 encephalitis is classified as a paraneoplastic neurological syndrome. It is often, but not always, triggered by an underlying tumor, most commonly a testicular germ cell tumor. In the second case, a testicular ultrasound found an epididymal calcification, potentially evidence of a “burnt-out” tumor that had been attacked by the immune system.

The hallmark symptoms of this encephalitis directly involve the auditory and vestibular systems. Patients frequently experience tinnitus, hearing loss, vertigo, and ataxia. This makes it a critical differential diagnosis for individuals presenting with sudden, unexplained auditory or balance disturbances that do not fit typical patterns. The condition underscores why a broad diagnostic view is necessary, similar to the approach recommended for cochleovestibular screening in neurosarcoidosis patients, another systemic inflammatory disease.

The profound auditory hypersensitivity experienced in some cases also creates a clinical overlap with conditions like hyperacusis and misophonia. While the root cause differs, the shared experience of sound intolerance suggests research into one area can inform another. Understanding the neural salience filter breakdown in misophonia may offer parallel insights into how autoimmunity disrupts central auditory processing.

### Practical Implications for Patients and Clinicians

This report has several immediate implications. First, it elevates awareness of anti-KLHL11 antibodies as a rare but treatable cause of severe tinnitus, vertigo, and hyperacusis. For clinicians, testing for these antibodies should be considered in patients with these symptoms alongside other neurological signs, especially if the onset is subacute.

Second, it reinforces the non-negotiable need for comprehensive cancer screening in such cases, including pelvic ultrasound and tumor marker tests, even if the tumor is not immediately obvious.

Finally, it introduces efgartigimod as a viable option for cases resistant to steroids and rituximab, expanding the therapeutic toolkit. Managing the significant anxiety and sleep disruption that often accompanies these severe symptoms is also vital. The stress of a chronic neurological condition can create a cycle where tinnitus and anxiety research trends show each worsens the other. Supportive behavioral therapies, including those that address sleep, remain a cornerstone of care. Improving sleep quality through methods like evidence-based sleep hygiene can be an important adjunct to immunotherapy.

The study by Han, Li, and Li, available with full details at DOI: 10.3389/fimmu.2026.1729540, moves the field forward by documenting a successful novel treatment and highlighting a factor that may predict treatment difficulty. It is a reminder that for a subset of patients with hearing and balance disorders, the cause may be an immune system gone awry, and the solution requires targeting that specific dysfunction.