Sudden Sensorineural Hearing Loss in an Immunocompetent Patient With West Nile Encephalitis

ABSTRACT

Objective

Sudden sensorineural hearing loss (SSNHL) is a frequently encountered condition that is often idiopathic but may be precipitated by infection. Neuroinvasive disease resulting from West Nile virus (WNV) is a rare cause of SSNHL, typically affecting immunocompromised patients and generally associated with minimal hearing recovery. We present a case of an immunocompetent woman who was diagnosed with SSNHL in the setting of a WNV infection and showed significant hearing improvement.

Methods

Case report and literature review.

Results

A 55‐year‐old immunocompetent female presented to our Otolaryngology office after several visits to the emergency department for worsening disequilibrium and new onset bilateral hearing loss. An audiogram demonstrated bilateral SNHL. After a thorough inpatient evaluation for hematologic, oncologic, immunologic, and infectious etiologies, CSF and serum IgG and IgM antibodies to WNV were elevated. The patient was managed conservatively and, at follow‐up, endorsed significant hearing improvement that was reflected on her repeat audiogram.

Conclusion

SSNHL in patients with neuroinvasive WNV is extremely rare, with only a small number of previously reported cases. WNV should be considered as a cause of SSNHL in the US, especially during the late summer and fall months. Patients should be counseled on the variable prognosis of the hearing loss, and early discussions regarding cochlear implantation should be pursued for patients without significant recovery of profound hearing loss.

Level of Evidence: IV

1. Introduction

Sudden sensorineural hearing loss (SSNHL) is a frequently encountered condition characterized by a drop of ≥ 30 dB in hearing over at least three consecutive frequencies within 72 h. Incidence of SSNHL is estimated at 5–27 per 100,000 and is increasing in the United States [1]. Most cases of SSNHL are idiopathic, posing a significant diagnostic challenge for clinicians. Although most cases are of unknown etiology, diagnosis involves evaluation of possible precipitating factors including neoplasms, autoimmune causes, infection, trauma, or medications. Among the most common suspected etiologies of SSNHL is acquired viral infection [2]. Acquired viruses that can cause SSNHL include human immunodeficiency virus (HIV), herpes simplex virus (HSV), measles virus, varicella zoster virus (VZV), mumps virus, and West Nile virus (WNV) [3]. Multiple hypotheses have been set forth to explain how viral infection can cause hearing loss including direct invasion of the inner ear, latent virus reactivation, and as an immune stress response [4].

WNV is an enveloped, single‐stranded RNA arbovirus that infects humans via a bite from an infected mosquito. Transmission is rare between humans but can occur transplacentally and through infected donor blood and breast milk [5]. The first outbreak of WNV in the Western Hemisphere was in New York in 1999, with 62 cases of encephalitis and 7 deaths [6]. Between 1999 and 2024, according to ArboNET, a national arboviral surveillance system managed by the Center for Disease Control (CDC) and state health departments, over 59,000 cases have been reported in the US, resulting in over 27,000 hospitalizations and almost 3000 deaths. Cases occur seasonally, with most reported in the late summer and fall. In 2024, over 1400 cases of WNV have been reported across 49 states, of which 1018 were neuroinvasive. Of note, less than 1% of those infected with WNV develop neuroinvasive disease; however, patients with neuroinvasive WNV are more likely to seek healthcare and be tested for WNV, which likely accounts for the relatively high proportion of reported neuroinvasive cases reported [7].

WNV has a wide spectrum of clinical presentations. Approximately 25% of those infected experience West Nile fever, which is characterized by myalgia, malaise, and a low‐grade fever [7]. The remaining 75% exhibit little to no symptoms. Neuroinvasive WNV is characterized by rapidly progressive severe muscle weakness, flaccid paralysis, changes in mental status, and seizures. In rare cases, neuroinvasive WNV can cause sudden bilateral sensorineural hearing loss. Among the few patients who developed acute hearing loss in the setting of West Nile encephalitis, some are immunocompromised, and there are mixed outcomes in case reports, ranging from no recovery to gradual improvement of hearing [8, 9, 10, 11, 12, 13]. Here, we present a case of an immunocompetent patient who presented with severe disequilibrium and sudden bilateral hearing loss with West Nile encephalitis and showed significant hearing improvement.

2. Case Report

The patient provided voluntary and written informed consent for the publication of her medical details in this case report. This report was reviewed according to the Institutional Review Board (IRB) guidelines, and IRB approval was deemed not required as per institutional policy.

The patient is a 55‐year‐old immunocompetent Caucasian female with a history of asthma, Graves' disease, and latent herpes simplex virus 2 (HSV2). She rarely needs to use her albuterol inhaler and takes no other medications. She has an allergy to codeine, no past surgical history, has never smoked tobacco, consumes alcohol socially up to three drinks per week, and has never used illicit drugs. She has no history of loud noise exposure, trauma, or family history of hearing loss.

She initially presented to an urgent care facility in Colorado in August 2024 with a 3‐day history of cough and dizziness after attending a concert. She received intravenous (IV) fluids and antiemetics with minimal relief and was discharged. She returned to the urgent care facility the following day with persistent symptoms, was prescribed meclizine, and discharged. The next day, she experienced severe nausea, vomiting, and disequilibrium causing her to lose balance and fall down the stairs. This prompted her to visit the emergency department. There, her exam was significant for a temperature of 101.9 F (38.8 C) and severe gait instability. Imaging for acute intracranial abnormalities including computed tomography (CT) of the head, CT angiogram of the head and neck, and contrasted magnetic resonance imaging (MRI) of the brain demonstrated no acute abnormality. She received diazepam, IV fluids, and ondansetron for suspected viral labyrinthitis and was discharged. Two days later, she returned to the emergency department with worsening vomiting and dizziness, as well as new‐onset bilateral hearing loss. She was started on a 10‐day course of amoxicillin and given a follow‐up appointment with Otolaryngology and Audiology.

She underwent audiologic evaluation 2 days later (Figure 1) that demonstrated a mild to severe down sloping bilateral SNHL and speech discrimination score (SDS) of 64% in the right ear and 88% in the left ear. She was started on a 7‐day prednisone taper by an outside otolaryngologist. She also continued taking her prescribed valacyclovir, given her history of latent HSV2. She presented to our Otolaryngology office 2 days later with persistent emesis, intermittent fevers to 104 F (40 C), hearing loss, and severe disequilibrium to the extent she could not ambulate independently. Her tuning fork examination was consistent with bilateral SNHL. Given the persistence of her symptoms, she was referred to the emergency department for an urgent neurologic evaluation and lumbar puncture.

FIGURE 1.

Week 1 and 7 audiograms demonstrating improvement in bilateral sensorineural hearing loss.

On exam in the Emergency Department, she was alert and oriented with a good mood and normal affect. Cranial nerve examination was significant for decreased hearing to finger rub bilaterally but intact to conversational voice. Motor strength, cerebellar testing, sensation, and Romberg test were unremarkable. Her gait was mildly wide‐based, cautious, and unsteady. Given the concern for encephalitis, she underwent further imaging, cerebrospinal fluid (CSF) studies, and evaluation for neoplastic, autoimmune, and infectious etiologies. Auditory brainstem response (ABR) was not performed given the acute nature of the patient's illness and the need for urgent hospitalization.

A repeat MRI of the brain with and without contrast demonstrated a new small diffusion restriction in the left medial medulla concerning for an ischemic stroke (Figure 2). She was not a candidate for thrombolysis or thrombectomy given her last known well of about 10 days prior. The small medullary stroke did not align with her prolonged fever and hearing loss, so another etiology was suspected. A transthoracic echocardiogram was unremarkable. Her initial comprehensive metabolic panel, complete blood count, lipid panel, hemoglobin A1c, and thyroid stimulating hormone levels were within normal limits.

FIGURE 2.

MRI of the brain with punctate left medial medullary lesion showing a pattern of diffusion restriction on (a) diffusion weighted imaging and (b) apparent diffusion coefficient sequences, concerning for acute infarct.

Her lumbar puncture demonstrated clear, colorless CSF with a lymphocytic pleocytosis of 52 white blood cells/mm³ (99% lymphocytes), mildly elevated protein of 52 mg/dL (reference range: 15–45), and normal glucose of 50 mg/dL (no serum glucose available at time of lumbar puncture; reference range: 40–70). CSF IgG index was elevated to 0.94 (reference range: 0.28–0.66) and CSF IgG synthesis rate was elevated to 9.0 mg/dL (reference range: ≤ 8.0). Unique CSF oligoclonal bands were elevated to 6 bands (reference range: 0–1). Aerobic and anaerobic CSF cultures showed no organism growth, and CSF cytology demonstrated no evidence of malignancy.

An extensive hematologic, oncologic, and immunologic evaluation was significant for an elevated erythrocyte sedimentation rate of 28 mm/h (reference range: 0–20), decreased serum IgG to 576 mg/dL (reference range: 768–1632), elevated serum IL‐17 to 1.6 pg/mL (reference range: ≤ 1.4), and elevated CSF IL‐2 receptor to 79.0 pg/mL (reference range ≤ 26.8). Otherwise, myeloid differentiation primary response protein 88 (MyD88) mutation detection, other inflammatory markers (C‐reactive protein and lactate dehydrogenase), leukemia and lymphoma B and T cell subsets, antiphospholipid antibody syndrome antibodies, activated protein C resistance, serum protein electrophoresis, autoimmune markers (rheumatoid factor, cytoplasmic and perinuclear anti‐neutrophil cytoplasmic autoantibodies (ANCAs), antinuclear antibodies), complement levels (C3, C4), and other serum and CSF cytokines were within normal limits.

A thorough infectious workup evaluated for bacterial and viral causes of encephalitis. Treponemal antibodies and Borrelia burgdorferi ELISA were negative. Viral workup was negative for COVID‐19, hepatitis B virus, hepatitis C virus, HSV 1/2, HIV 1/2, influenza A/B, respiratory syncytial virus, and VZV. WNV serum IgG was elevated to 2.32 (reference range: ≤ 1.29), WNV serum IgM was elevated to 6.85 (reference range: ≤ 0.89), WNV CSF IgG was elevated to 2.87 (reference range: ≤ 1.29), and WNV CSF IgM was elevated to 7.12 (reference range: ≤ 0.89). Steroids and valacyclovir were discontinued after no clinical improvement was seen and an infectious etiology was confirmed. The patient received no further systemic steroids, nor did she ever receive intratympanic steroids.

Given the patient's positive serum and CSF WNV antibodies, a diagnosis of West Nile encephalitis (WNE) was made. During her hospital stay, her nausea was managed conservatively, and she experienced subjective improvement in her nausea, disequilibrium, and hearing. Secondary stroke prevention (aspirin and atorvastatin) was initiated given her possible medullary stroke, and she was discharged with follow‐up appointments with Otolaryngology and Neurology. At Otolaryngology follow‐up, she reported significant hearing improvement. This was corroborated by her repeat audiogram (Figure 1) that demonstrated mild to moderate bilateral sensorineural hearing loss with interval improvement and SDS improved to 92% in the right ear and 100% in the left ear. At her neurology follow‐up, she was continued on aspirin for stroke prevention and atorvastatin was discontinued. Her montreal cognitive assessment (MoCA) score was 23/30, demonstrating persistent mild cognitive impairment in the domains of visuospatial/executive function, naming, language, and delayed recall. Through her most recent follow‐up about 10 weeks after symptom onset, she has continued to improve. She has a follow‐up with otolaryngology and audiology in 6 months to reevaluate her hearing, as well as a follow‐up with Neurology to repeat her neurologic examination, including the MoCA.

3. Discussion

Since the 1999 outbreak in New York, the incidence of WNV has fluctuated between 700 and 10,000 new cases per year in the US, according to the national arboviral surveillance system. Although rare, hearing loss has been documented as a complication of neuroinvasive disease. Treatment of neuroinvasive WNV relies mainly on supportive care, as did our patient's. Of the small number of reported cases, there have been mixed degrees of hearing recovery, with those patients who do experience improved hearing doing so over a period of many months. We present a notable case of an immunocompetent patient with severe West Nile‐associated hearing loss who experienced rapid and significant improvement in her hearing over 6–8 weeks.

Our patient with WNE presented with worsening disequilibrium, nausea, and hearing loss. Initial treatment with a prednisone taper was discontinued due to worsening symptoms. She was subsequently managed with supportive care alone, after which she reported subjective improvement in nausea, disequilibrium, and hearing. She experienced subjective recovery of her bilateral SNHL at her eight‐week follow‐up, corroborated by a repeat audiogram. The mainstay of treatment for WNV infection is supportive management. Certain agents that may be of potential benefit to a patient with WNV infection include corticosteroids and intravenous immunoglobulin; however, the existing literature on these interventions is limited and conflicting. Regarding corticosteroids, treatment has led to clinical improvement in several case reports of patients with neurological complications of WNV infection [14, 15, 16]. Two nonrandomized studies of patients with neuroinvasive WNV found no difference in time to discharge, hospital mortality, or neurological sequelae at discharge between untreated patients and those treated with steroids [17, 18]. Therefore, we recommend against the routine use of steroids for patients with neuroinvasive WNV and advise close monitoring of symptom progression to guide the decision to continue or discontinue steroid therapy.

A large observational study of West Nile virus‐infected patients in Houston documented neurological abnormalities in patients at 1–3‐year and 8–11‐year time points from initial infection [13]. WNE patients were older, more likely male, and had higher rates of comorbidities such as diabetes mellitus, prior stroke, alcohol use disorder, and hypertension. The most common neurologic symptoms at the 1–3‐year follow‐up were tandem gait abnormalities (60%), hearing loss (46%), motor weakness (37%), vibratory sensation deficit (31%), abnormal reflexes (26%), and tremor (20%). Of the patients that followed up at the 8–11‐year time point, all patients with tandem gait abnormalities and all patients with hearing loss had persistent symptoms. Balance and gait abnormalities seen in neuroinvasive West Nile disease have been reported in multiple studies, but the etiology and clinical course remain unclear. The advanced age and high rate of comorbidities in the study's cohort compared to our patient offer a possible explanation for why our patient's hearing improved.

Compared to that large observational study from 2015, case reports of immunocompetent patients with WNV‐associated hearing loss have detailed variable hearing prognoses. Using the following search terms on PubMed, we compiled the existing literature related to WNV and associated hearing loss: (West Nile virus) AND (hearing loss) (Table 1). Several case reports described persistent hearing deficits at follow‐up evaluations. These range from 2 to 3 months to longer follow‐up periods, consistent with the findings of Weatherhead et al., of 3–10 years [8, 9, 12]. However, others demonstrate findings more consistent with our patient. For example, a two‐patient case series published in 2019 of a 56‐ and 75‐year‐old patient, both with bilateral SNHL and positional vertigo, reported gradual improvement in hearing over 7 months from the initial infection [11]. It is notable, however, that hearing was not retested earlier than 7 months from acute presentation, so it is unclear at what point during those 7 months the patients' hearing recovered. Additionally, the 56‐year‐old patient had no documented comorbidities, and the 75‐year‐old patient was reported to have several unspecified comorbidities. That same year, a three‐patient case series of a 63‐, 75‐, and 25‐year‐old patient, each with bilateral SNHL, reported no hearing improvement over long‐term follow‐up of up to 10 years [12]. In this series, the 63‐ and 75‐year‐old patients had comorbid diabetes mellitus and hypertension.

TABLE 1.

Summary of previous reports of sudden sensorineural hearing loss in patients with West Nile virus (WNV) infections.

Author	Year	Study Type	Age	Sex	Comorbidities	Immuno‐ compromised	Diagnosis	Imaging	Outcome
Casetta et al.	2011	Case report	55	Male	NR	No	Serum and CSF IgM and IgG antibodies to WNV	MRI brain and spine unremarkable	No hearing improvement at 3‐month follow‐up
Jamison et al.	2007	Case report	41	Male	Hypertension, HIV	Yes	Serum IgM and IgG antibodies to WNV	CT head demonstrated mild atrophy; MRI head and spine unremarkable	No hearing improvement, patient expired 2 months after hospitalization
McBride et al.	2006	Case report	57	Female	Myasthenia gravis	Yes – on immuno‐ suppressive therapy for myasthenia gravis	CSF: 50 leukocytes/μL with 85% PMNs CSF IgM antibodies to WNV Serum IgM and IgG antibodies to WNV	MRI brain unremarkable	Gradual hearing improvement
Parrino et al.	2019	Case series	56	Male	NR	NR	Serum IgM antibodies to WNV and WNV RNA	None	Hearing improvement at 7‐month follow‐up
			75	Male	“Several”	NR	CSF: 180 leukocytes/mm3 with 95% lymphocytes CSF IgM antibodies to WNV Serum antibodies to WNV and WNV RNA	CT brain unremarkable	Hearing improvement at 7‐month follow‐up
Pradhan et al.	2019	Case series	63	Male	Hypertension, diabetes	No	CSF: 430 leukocytes/dL with 60% PMNs and 40% lymphocytes CSF qPCR for WNV positive	MRI brain showed hyperintensities in the substantia nigra, caudate, external capsule, parieto‐occipital region, and corona radiata	No hearing improvement at 10‐year follow‐up
			75	Male	Hypertension, Diabetes	No	Serum RT‐PCR for WNV positive	MRI brain showed hyperintensities in the corona radiata	No hearing improvement at 3‐year follow‐up
			25	Male	None	No	CSF: 104 leukocytes/dL	MRI brain showed hyperintensities in basal ganglia Serum qRT‐PCR for WNV positive	No hearing improvement at 3‐year follow‐up
Szatmary et al.	2014	Case report	57	Male	NR	NR	CSF: 1519 leukocytes with 100% granulocytes CSF IgM and IgG antibodies to WNV	MRI brain unremarkable	No hearing improvement and required hearing aids

Abbreviations: HIV, human immunodeficiency virus; NR, not recorded; PMN, polymorphonuclear leukocyte; qRT‐PCR, quantitative reverse transcriptase polymerase chain reaction; RT‐PCR, reverse transcriptase polymerase chain reaction.

Her pure tone audiometric improvement across all frequencies suggests that the cochlear involvement was not limited to a specific region. The role of neurotropic viruses in hearing impairment and vestibulopathy is not fully understood. Chen et al. hypothesized this may be caused by viral invasion of the cochlea or cochlear nerve, reactivation of latent viruses in inner ear structures, or by immune cross‐reaction with an inner ear antigen [4]. Microscopic analysis of the vestibular nerve in patients with vestibular neuritis and Meniere's disease has demonstrated the presence of viral particles, suggesting a potential viral etiology of these causes of hearing loss and potentially other types of hearing loss [19].

A limitation to our study is that it lacks generalizability, given it is a single case report. Further research of patients with WNV infections, particularly neuroinvasive disease, is needed to improve our understanding of the mechanism, risk factors, and prognosis of SNHL in the setting of a WNV infection. Further study is needed to determine how comorbidities may affect the clinical course of WNE and associated hearing loss. WNV should be considered as a cause of SSNHL in the US, especially during the late summer and fall months, as has been reported previously and supported by our experience. Patients should be counseled appropriately on the variable prognosis of the hearing loss. We recommend that once the acute symptoms of encephalitis have stabilized, a patient's hearing should be monitored closely with repeat audiometric evaluations. ABR testing may also offer valuable diagnostic insights if the patient's condition permits it to be performed. In the setting of a profound unilateral or bilateral hearing loss without significant recovery, early discussions regarding cochlear implantation should be considered to allow for successful implantation prior to cochlear ossification.

4. Conclusion

Hearing loss associated with neuroinvasive WNV has been reported with variable prognosis. The case we present is notable because our patient experienced rapid and significant improvement in her hearing over 8 weeks with supportive management. Given the rarity of WNV associated SSNHL, we recommend maintaining a broad differential and conducting a thorough workup for patients with worsening signs of encephalitis. We also recommend closely monitoring a patient's hearing after the acute symptoms of encephalitis have stabilized.

Conflicts of Interest

The authors declare no conflicts of interest.

Malhotra R., Schmitt B., Tyler K., and Agrawal Y., “Sudden Sensorineural Hearing Loss in an Immunocompetent Patient With West Nile Encephalitis,” Laryngoscope Investigative Otolaryngology 10, no. 4 (2025): e70206, 10.1002/lio2.70206.

Data Availability Statement

Our data is available in whatever form necessary, but this may not be applicable given the nature of this case report.