Association Between Calcium Metabolism and Inner Ear Function: Evidence of Auditory and Vestibular Dysfunction in Primary Hyperparathyroidism
Description
The aim of this study is to evaluate the vestibular and auditory functions of patients with primary hyperparathyroidism. (PHPT) he experimental group composed of 25 patients with PHPT, and the control group composed of 25 age- and sex-matched healthy adults. The participants underwent a standardized audiovestibular assessment. The audiological battery included tympanometry, pure-tone audiometry (PTA), speech discrimination (SD), and speech reception threshold (SRT). Vestibular function was assessed with videonystagmography (VNG), video head impulse test (vHIT), and symptom burden was quantified using the Dizziness Handicap Inventory (DHI). In addition, a binary logistic regression analysis was performed to evaluate whether bone mineral density (BMD), parathyroid hormone (PTH), vitamin D, and calcium levels were associated with the presence of pathological saccades (0 = absent, 1 = present). The groups were statistically similar in terms of sex distribution and age. Patients with PHPT exhibited significantly elevated pure-tone thresholds at 250-8000 hz and higher mean PTA and SRT values compared with controls, while mean SD scores were slightly lower but not statistically significant. VOR gains on vHIT were significantly reduced across all semicircular canals in the PHPT group, whereas VNG findings did not differ between groups. DHI total scores were also significantly higher in the PHPTgroup, indicating greater perceived vestibular disability. There was no significant association between BMD, PTH, vitamin D, or calcium levels and the presence of pathological saccades PHPT is associated with subclinical auditory and vestibular dysfunction, likely mediated by disturbances in calcium and vitamin D metabolism, underscoring the importance of early evaluation and follow-up in this population. In this prospective case–control study, we comprehensively evaluated auditory and vestibular function in patients with primary hyperparathyroidism (PHPT) with specific attention to calcium and vitamin D metabolism. Compared with age- and sex-matched controls, PHPT patients exhibited elevated hearing thresholds, reduced vestibulo-ocular reflex gains on vHIT, and higher DHI scores, while conventional VNG parameters did not differ. We also performed logistic regression including bone mineral density, parathyroid hormone, vitamin D, and calcium; none showed a significant association with pathological saccades. These findings suggest subclinical audiovestibular involvement in PHPT and highlight the potential value of routine screening in this population. This study is, to our knowledge, the first to demonstrate objective canal dysfunction on vHIT alongside subclinical hearing impairment in PHPT.
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Steps to reproduce
Videonystagmography: The videonystagmography (VNG) test battery was performed using Visual Eyes™ (Interacoustics, Middlefart, Denmark) to assess vestibulo-ocular reflexes and nystagmus. After calibration, tests were performed sequentially. The VNG test battery included spontaneous nystagmus test, oculomotor tests (gaze, saccade, smooth pursuit and optokinetic tests), head shake test and positional (Dix-Hallpike maneuver, supine roll maneuver) tests. Video Head Impulse Test: vHIT measurements were obtained with the EyeSeeCam vHIT system (Interacoustics A/S, DK-5610, Assens, Denmark), and data were analyzed using OtoAccess™ software. Goggles with a monocular camera that can be changed to the right and left side, a laser source placed in the middle, and fixed to the head with a rubber band were used. Participants were seated 1.2 m from a plain blank wall. The camera position was adjusted to provide a clear view of the pupil, and the system was calibrated before testing. The protocol comprised three subtests assessing the lateral (horizontal) and the anterior and posterior (vertical) semicircular canals (SCCs) in both ears. Throughout the procedure, subjects were instructed to relax the head–neck musculature and not to take his eyes off the target point set during the calibration on the wall.(11). Head impulses were delivered in the six SCC planes according to McGarvie et al (12). For the horizontal canals, the examiner grasped the head with both hands and applied small-amplitude, rapid, unpredictable head thrusts to the right and left at an angle of 15°. For the vertical canals, the head was oriented 45° toward the side being tested and impulses were applied forward and backward while the subject maintained visual fixation. At least ten impulses were recorded for each canal. Vestibulo-ocular reflex (VOR) gain and gain asymmetry (GA) were calculated for all canals. GA defined as follows: GA = (Right SSC gain − left SSC gain) / (Right SSC gain + left SSC gain) × 100. Overt and covert corrective saccades were identified. An abnormal vHIT response was defined as a VOR gain < 0.80 and/or the presence of corrective saccades with peak velocity > 100°/s. (13). Subjective Vestibular Assessment: The Dizziness Handicap Inventory (DHI) is a commonly utilized standardized questionnaire for assessing the perceived effects of dizziness on daily activities. DHI was originally developed and validated in English by Jacopson and Newman (14) and adapted and validated for Turkish population by Canbal et al. (15) The DHI consists of 25 questions and examines the effects of dizziness as 'physical' (7 questions), 'emotional' (9 questions), and 'functional' (9 questions) under three subheadings. The participants' answers to every question are scored as never (0 points), sometimes (2 points), and always (4 points), and therefore, the overall score varies between 0 and 100. A higher score means that the negative effect of dizziness is more excess.
Institutions
- Ondokuz Mayis Universitesi Tip FakultesiSamsun