Assessment of Saccular Function in Patients With Noise Induced Hearing Loss

BACKGROUND AND OBJECTIVES: Considering saccular receptors are coupled physically with the auditory receptors, VEMP test may provide the information that in the noise induced hearing loss with or without dizziness, damage to the vestibular system, especially saccule is a potential organ with cochlear damage. MATERIAL AND METHODS: 11 patients (22 ears) with HF-SNHL greater than 55dB and 10 patients (10 ears) with sudden hearing loss of varying degree HL as positive control but without clinical manifestations of vestibular pathology tested for vestibular function test was enrolled. VEMP test was done. The results were compared with those of 9-healthy referents (18 ears) examined in the same way. RESULTS: VEMP wave was significantly abolished as twelve of 22 (54.5%) with HF-SNHL, five of 13 (38.5%) and Control group (100%). Though there was no statistically significant relation with P13, N23 latency delay in each group, NIHL showed P13, N23 latency delay trend compared with controls. CONCLUSIONS: Patients with noise induced hearing loss showed significantly more saccular deterioration, estimated as negative VEMP responses than did the controls. This suggests subclinical disturbances of the vestibular system especially of the saccule in noise induced hearing loss.

Comparative Analysis of Vestibular Asymmetry Parameters in Acute Unilateral Peripheral Vestibulopathy

BACKGROUND AND OBJECTIVES: There are known parameters that indicate vestibular asymmetry, such as directional preponderance (DP) on caloric test, asymmetry on slow harmonic acceleration (SHA) test, asymmetry of time constant (Tc) and slow cumulative eye position (SCEP) on velocity step test. Aim of this study is investigate the sensitivity and predictability of the vestibular asymmetry parameters among them. MATERIALS & METHODS: Twenty six patients who were diagnosed as acute unilateral peripheral vestibulopathy were enrolled in this study. We compared each parameter with site of lesion based on the direction of spontaneous nystagmus and canal paresis (CP) which were totally correlated in this group of patients. RESULTS: Positive predictability of each parameter showed 58% in DP, 62% in SHA asymmetry, 62% in SCEP, 38% in Tc. In the cases that each parameter showed positive result, all of DP and SHA asymmetry indicated site of lesion, and showed high correlation coefficient(r=0.89). But in 27% of SCEP and 23% of Tc did not indicate site of lesion. CONCLUSION: All parameters showed low sensitivity for identifying laterality of lesion even the tests were performed within one week after vertigo attack. DP and VOR asymmetry showed high positive predictability for indicating lesion site.