Audiological Outcomes in Cervical Spine Pathologies
Article information
Abstract
Background and Objectives
The objective of this study was to evaluate the potential effects of loss of cervical lordosis (LCL) and cervical disc pathologies (CDPs) on the auditory system and to identify the predominant anatomical sites of these effects using both objective and subjective audiological assessments.
Subjects and Methods
This prospective controlled study included 98 individuals: 57 patients diagnosed with CDP via cervical spinal magnetic resonance imaging and 41 individuals without such a diagnosis. Of the participants, 68 (69.4%) were female, and 30 (30.6%) were male. CDP was assessed based on the presence and level of bulging or protrusion. Cervical lateral radiographs revealed LCL in 65 patients, while 33 showed no such loss. The mean age of participants was 41.0±6.9 years (range: 21–52 years). All participants underwent audiological evaluation, including assessment of hearing thresholds and the presence of tinnitus.
Results
The mean speech frequency and high-frequency hearing thresholds, measured by pure-tone audiometry, were significantly higher in the 57 patients with CDP than in the 41 control participants (p=0.04 and p=0.02, respectively). However, no statistically significant differences were observed in speech frequencies, high-frequency hearing thresholds, and otoacoustic emission measurements, as assessed by pure-tone audiometry, between the 65 patients with LCL and the 33 control participants without LCL (p=0.22, p=0.18, p=0.51, respectively). Upon evaluating the groups for the presence and severity of tinnitus, no differences in LCL or CDP were observed (p=0.81 and p=0.95, respectively).
Conclusions
Our findings indicate that patients with CDPs exhibit elevated hearing thresholds. Given the limited number of studies addressing inner ear function in common conditions such as cervical disc herniation and LCL, this study contributes to the literature by emphasizing the importance of auditory assessments in these patients.
Introduction
Sensorineural hearing loss (SNHL) is a type of hearing impairment characterized by air conduction and bone conduction hearing thresholds above normal limits, with the air-bone gap being less than 10 dB. SNHL may be observed in cases of head trauma, acoustic trauma, use of ototoxic medications, inner ear anomalies, and presbycusis. While conventional audiometry typically assesses frequencies between 250 Hz and 8 kHz, high-frequency audiometry measures hearing thresholds within the 10 kHz to 16 kHz range [1,2]. The hair cells responsible for transmitting high-frequency sounds are located in the basal region of the cochlea and are known to be the most susceptible cells to damage, being the first to be affected [3]. Today, high-frequency audiometry has become a superior and more important diagnostic measurement tool compared to conventional speech frequency assessments, particularly in evaluating the impact of aging, noise exposure, ototoxicity, and metabolic diseases on the cochlea [4].
It has been demonstrated that any abnormality of the cervical spine may affect inner ear arteries or nerves and impair their functions through various mechanisms [5]. Cervical disc pathology (CDP) is a clinical condition resulting from the compression of a cervical spinal nerve root by degenerated disk material [6]. CDP, as well as other cervical spine disorders such as osteoarthritis and rheumatoid arthritis, may lead to symptoms including hearing loss, dizziness, and tinnitus [7].
Cervical lordosis is the natural curvature of the cervical spine, contributing to the balance of the weight of the head. Loss of cervical lordosis (LCL) is a pathology that results from increased biomechanical stress on the neural and vascular structures within the cervical spine [8].
The aim of our study is to evaluate the potential effects of LCL and CDP on hearing function within the inner ear using both objective and subjective audiological assessments.
Subjects and Methods
The study was initiated after obtaining approval from the Institutional Review Board of Samsun University Medical School (GOKAEK 2024/7/9), and informed voluntary consent forms were obtained from all participants.
The study was designed as a controlled prospective study. A total of 98 patients (68 [69.4%] females) who presented to our hospital’s neurosurgery outpatient clinic between March 2024 and March 2025 and were investigated for CDP with cervical spine magnetic resonance imaging (MRI) and LCL with lateral X-ray were included. The mean age of the patients included in the study was 41.0±6.9 (range: 21–52). Patients with comorbidities such as a history of cervical surgery or cervical trauma due to cervical pathologies, prior otologic surgery, occupational noise exposure, acoustic trauma, neurological diseases, diabetes mellitus, hypertension, hormonal dysfunction, or inflammatory rheumatologic disease, as well as those with a history of psychiatric illness, were excluded from the study.
The hearing thresholds of the participants included in the study were measured according to the current clinical standards (ISO 8253-1, 1989) using pure-tone audiometry (PTA), including frequencies between 125 Hz and 8 kHz, and high-frequency pure-tone audiometry (HF-PTA), including frequencies between 10 kHz and 18 kHz. The measurements were conducted in a soundproof booth using a two-channel Interacoustics AC-40 audiometer (headphone: TDH39). The average values of the obtained data were calculated to determine the PTA and HF-PTA values. Additionally, tympanometry and otoacoustic emission measurement (using an Otometrics Madsen Capella device with OTOsuite software) were performed to rule out possible middle ear pathologies and support the PTA thresholds of the participants. Tympanometric tests were evaluated at a probe tone frequency of 226 Hz using impedance audiometry (Demant Maico), and patients with Type A tympanogram were included in the study to exclude middle ear pathologies [9].
For tinnitus assessment, the Tinnitus Handicap Inventory (THI) and the Turkish version of the International Tinnitus Inventory (Tr-ITI) were administered [10,11]. The THI consists of 25 items to assess the participants’ levels of tinnitus. The Tr-ITI consists of eight items, each scored on a scale ranging from 1 (very difficult) to 5 (no difficulty at all), and the total scores are summed up. The severity of tinnitus was evaluated by comparing the average questionnaire scores between the two groups.
CDP was determined by examining the presence of bulging and/or protrusion in the cervical disc in the sagittal and axial planes using MRI. In patients with identified CDP, the pathology was classified based on its location in the upper cervical region if the pathology was at the C3-4 and C4-5 segments, and in the lower cervical region if the pathology was at the C5-6 and C6-7 segments.
LCL was assessed by measuring the angle between two lines drawn perpendicular to the lower end plate of the C2 vertebra, the straight line drawn, and the lower end plate of the C7 vertebra on lateral cervical radiographs taken in the neutral position using imaging software. Values below 20° were considered indicative of LCL.
Patients with and without CDP and LCL were compared in terms of age, sex, PTA, HF-PTA, transient evoked otoacoustic emissions (TEOAE), cervical Cobb angle, tinnitus presence, and severity. A power analysis was conducted using G*Power (version 3.1.9.7; Heinrich Heine University Düsseldorf) to determine the sample size for the study. Based on Cohen’s effect size coefficients, a one-way analysis of variance (ANOVA) was performed with an effect size of d=0.80, a Type I error level of α=0.05, a power of 1-β (β=probability of Type II error)=0.95, and a minimum sample size of 26 individuals in each group was calculated. The effect size was calculated as 0.6, and the actual power was 1, calculated using G*Power (version 3.1.9.2; Heinrich-Heine-Universität Düsseldorf).
Statistical analysis
All data were analyzed using SPSS software for Windows (version 21.0; IBM Corp.). Descriptive statistics were used to summarize the data, including means, percentages, medians, frequency distributions, and standard deviations for individual and total data. The normality of data distribution was confirmed using the Kolmogorov–Smirnov test due to a sample size of more than 50. Parametric variables were analyzed using t-tests and Pearson correlation analysis, while non-parametric variables were analyzed using the Mann–Whitney U test and Spearman correlation analysis. A p-value <0.05 was considered statistically significant.
Results
The study group consisted of 65 patients with LCL, and the control group comprised 33 individuals without LCL. In total, 98 participants were evaluated, including 65 females (66.3%) and 33 males (33.7%).
There were no statistically significant differences between patients with LCL and the control group in terms of age, PTA, HF-PTA, TEOAE, and the presence of tinnitus (p=0.07, p= 0.22, p=0.18, p=0.51, p=0.81, respectively). The cervical Cobb angle was significantly lower in the study group compared to the control group (p<0.01) (Fig. 1 and Table 1). There was a statistically significant difference between patients with LCL and the control group in terms of sex. However, in the two-way ANOVA, sex alone was not found to have a significant effect on hearing loss (p=0.87). In the same analysis, LCL alone showed a possible effect on PTA (p=0.06). A significant interaction was identified between LCL and sex (p=0.034). When these three parameters were evaluated together, it was concluded that the presence of LCL in males increases the tendency toward hearing loss. However, in HF-PTA, sex alone had no significant effect on hearing loss (p=0.83). Similarly, for CDP, sex alone had no effect on PTA or HF-PTA (p=0.27 and p=0.07, respectively).
The presence of tinnitus in LCL, CDP, and control groups. LCL, loss of cervical lordosis; CDP, cervical disc pathology.
Demographic, audiological, and cervical Cobb angle characteristics of patients with and without LCL
A correlation analysis was conducted to determine the correlation between PTA scores and direct radiographic findings, revealing a negative low-grade correlation between the cervical Cobb angle and HF-PTA scores, although it was not statistically significant (ρ=−0.16; p=0.21). Additionally, a positive correlation was found between age and PTA, as well as HF-PTA in patients with LCL (p=0.01, ρ=0.34 and p<0.01, ρ=0.51, respectively).
The study group comprised 57 patients with CDP, and the control group comprised 41 individuals without CDP. Overall, 68 participants (69.4%) were female and 30 (30.6%) were male. The demographic, audiological, and MRI findings of patients with CDP and those without CDP are shown in Table 2. PTA and HF-PTA values were significantly higher in the study group compared to the control group (p=0.04 and p=0.02, respectively). The cervical Cobb angle and TEOAE were significantly lower in the group with CDP compared to the control group (p=0.01 and p=0.02, respectively) (Table 2).
Demographic, audiological, and lateral cervical radiograph characteristics of patients with and without CDP
Among the patients with CDP, 17 (30%) had pathology in the upper cervical region (C3-4 and C4-5); 40 (70%) had pathology in the lower cervical region (C5-6 and C6-7). There were no statistically significant differences between the level of pathology and PTA, HF-PTA, TEOAE, and Cobb angle (p= 0.71, p=0.77, p=0.23, and p=0.77, respectively).
Among the patients with CDP, 37 (65%) had bulging, 14 (25%) had protrusion, and 6 (10%) had both bulging and protrusion. There were no statistically significant differences between the type of CDP and PTA, HF-PTA, and TEOAE (p= 0.78, p=0.48, and p=0.23, respectively).
Among the patients with CDP, 40 (70%) had LCL, while 17 (30%) did not. CDP was detected in 40 (62%) of the patients with LCD, while it was not observed in 25 (38%) (p=0.39).
Discussion
Vertebrogenic hearing loss, which may present with symptoms such as aural fullness, tinnitus, otalgia, and hearing impairment in cases of cervical dysfunction, was first described by Palmer in 1985 [12]. Subsequent studies have demonstrated that cervical spinal abnormalities, particularly in the upper segments, may affect the arteries or nerves related to the inner ear and impair their function through various mechanisms [12]. Another proposed mechanism involves proprioceptive pathway activation due to cervical pain, which may alter the intensity coding of auditory neurons, leading to hearing loss and tinnitus [9]. Pathologies such as osteoarthritis, rheumatoid arthritis, and cervical disc herniation may exert pressure on the basilar artery or the anterior inferior cerebellar artery in the upper cervical vertebrae, potentially resulting in auditory symptoms including hearing loss and tinnitus [12].
Vasaghi-Gharamaleki, et al. [13] reported that male patients with restricted left cervical rotation following cervical trauma had a higher likelihood of hearing loss at pure-tone thresholds (250, 500, 1,000, 2,000 Hz). Similarly, Karam, et al. [12] found significantly elevated hearing thresholds in male patients with cervical spondylosis and limited left rotation.
Previous studies had proposed that decreased vertebral artery hemodynamics, along with weakness and atrophy of the neck extensor muscles, may contribute to the pathogenesis of LCL [13]. LCL, a common cervical pathology, may arise from prolonged poor posture, degenerative disc disease, or trauma. Common symptoms include chronic neck pain, headaches, back pain, and restricted movement [14]. To the best of our knowledge, there are no existing studies in the literature that evaluate hearing in patients with LCL. In our study, no statistically significant difference in hearing thresholds was found between the LCL group and the control group.
Cervical disc herniation refers to the clinical condition caused by degenerative disc material compressing cervical spinal nerve roots, often seen in young adults [14]. “Bulging” describes a condition where the intervertebral disc material protrudes beyond its normal boundaries while the annulus fibrosus remains intact. In contrast, “protrusion” involves focal herniation of the nucleus pulposus through a tear or weak spot in the annulus fibrosus [15,16]. In line with the literature, our study found significantly elevated hearing thresholds at both speech and high frequencies in patients with CDP compared to the control group.
Karam, et al. [12] suggested that restricted cervical rotation may be associated with both hearing loss and dizziness. Vasaghi-Gharamaleki, et al. [13] similarly showed that rotational limitations following cervical trauma could lead to auditory dysfunction. Our study supports the hypothesis that CDP may contribute to hearing loss, in line with previous reports.
Audiological symptoms such as hearing loss and tinnitus appear to be less common in lower cervical pathologies compared to upper cervical ones. Cervical rotation predominantly occurs in the upper cervical region, particularly at the atlantoaxial joint [5]. However, in our study, no significant difference was observed in PTA thresholds, HF-PTA, and TEOAE values between upper and lower cervical disc pathologies.
Cervical pathologies not only contribute to hearing loss but may also play a role in tinnitus. Cervical spine dysfunction may compromise vertebral artery flow, thereby affecting blood supply to the cochlea and auditory pathways, which could exacerbate tinnitus. Compression of cervical nerves may result in abnormal signaling to the auditory cortex, potentially manifesting as tinnitus [17]. Michiels, et al. [18] found that cervical spine dysfunction was significantly more prevalent in patients with cervicogenic somatic tinnitus compared to other tinnitus patients in a cohort of 87 subjects.
LCL, cervicogenic somatic tinnitus, and cervicogenic vertigo share certain pathophysiological features. In a study by Delen, et al. [8], tinnitus was more prevalent in patients with LCL (n=24; 25%) compared to those without (n=46; 17.4%), though the difference was not statistically significant (p=0.53). Another study showed that among 42 patients diagnosed with lower cervical disc herniation, 57.5% reported dizziness, while 47.5% reported tinnitus, most commonly at 6,000 Hz and 55 dB. In a study evaluating cervical vestibular-evoked myogenic potentials (c-VEMP), patients with LCL had significantly lower c-VEMP presence, delayed P1 latencies, and reduced P1-N1 amplitudes compared to controls [19].
Contrary to the literature, our study found no significant relationship between the presence or severity of tinnitus and either CDP or LCL. HF-PTA thresholds were observed to be significantly higher in the CDP group compared to the control group (p=0.02). PTA speech thresholds, on the other hand, were borderline significantly higher than in the control group (p=0.04). It is known that cochlear damage initially affects high frequencies, causing inner hair cell dysfunction, which subsequently leads to subjective tinnitus sensation due to abnormal neural activity in the brainstem and cortex. Hearing loss is known to affect speech frequencies later. Similar to the involvement of speech frequencies, tinnitus may represent a symptom that could emerge in patients at a later stage. Additionally, the lack of difference in tinnitus may be due to the inclusion of younger and middle-aged patients without comorbidities known to contribute to tinnitus. To our knowledge, this is the first study to specifically evaluate the effects of cervical pathologies on inner ear function in a cohort without confounding systemic diseases.
Because cochlear damage typically begins at the basal turn and progresses apically, high-frequency audiometry can detect early dysfunction before speech frequencies are affected. This highlights the importance of incorporating high-frequency audiometry in routine evaluations for patients at risk of hearing loss due to cervical pathologies [20]. It may serve as a valuable tool in identifying early auditory changes linked to cervical spine disorders.
Treatment of cervical pathology has been shown to improve tinnitus symptoms [10]. Yang, et al. [21] demonstrated that patients undergoing anterior cervical decompression surgery for cervical spondylosis experienced greater improvement in tinnitus severity and functional scores compared to those managed conservatively. This improvement may be related to restored blood flow to the inner ear or relief of nerve root compression. However, there is limited evidence in the literature that treatment of cervical pathologies can reverse or halt the progression of hearing loss. We consider that if high-frequency hearing loss can be detected before speech frequencies are affected, management of the underlying cervical pathology may contribute to preventing further progression, or at least necessitate close monitoring and the implementation of preventive measures to preserve hearing. However, to assert that treatment of cervical pathology can indeed halt this progression, longer follow-up periods and post-treatment hearing outcome evaluations would be more appropriate.
Based on the findings of our study, it may be inferred that CDP has a greater impact on the auditory system than LCL. Given this association, audiological assessment should be considered in the clinical evaluation of patients with CDP to facilitate early diagnosis and possible rehabilitation. Furthermore, evaluation of inner ear function should include both speech and high-frequency hearing thresholds.
Our study has some limitations. First, the sample size was relatively small, which may be attributed to the exclusion of patients with comorbid conditions such as diabetes and hypertension. Second, audiological evaluations following treatment of CDP were not included. This limitation stems from the individualized nature of cervical pathology management, which precluded treatment standardization across the cohort. Nevertheless, to our knowledge, this study is the first to comprehensively evaluate the impact of both CDP and LCL on hearing and tinnitus, providing a foundation for future research.
In conlusion, in patients diagnosed with LCL and CDP, hearing loss and tinnitus symptoms should be thoroughly evaluated. In addition to standard PTA, high-frequency audiometry should be utilized to monitor auditory thresholds over time.
Notes
Conflicts of Interest
The authors have no financial conflicts of interest.
Author Contributions
Conceptualization: Hande Arslan. Data curation: Zeynep Özer, Cem Demirel. Formal analysis: Hande Arslan. Investigation: Hande Arslan, Zeynep Özer. Methodology: Hande Arslan. Project administration: Hande Arslan. Software: Zeynep Özer, Cem Demirel. Supervision: Doğukan Özdemir. Validation: Doğukan Özdemir. Visualization: Doğukan Özdemir, Merve Mutlu Çekim. Writing—original draft: Hande Arslan. Writing—review & editing: Hande Arslan, Doğukan Özdemir, Merve Mutlu Çekim. Approval of final manuscript: all authors.
Funding Statement
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Acknowledgments
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