Cervical Vestibular Evoked Myogenic Potentials (cVEMPs) Evoked by Air-Conducted Stimuli in Patients with Functional Neck Dissection.

OBJECTIVE: Cervical vestibular-evoked myogenic potentials (cVEMPs) are short-latency vestibulocollic reflexes. The damage on any point of the vestibulocollic reflex pathway could affect the cVEMPs. Whether neck dissection has an effect on the sacculocollic pathway, and consequently on cVEMPs, remains unexplored. The aim of this study was to evaluate the cVEMP findings in patients with functional neck dissection without vestibular symptoms.

PATIENTS AND METHODS: This cross-sectional study design, 20 patients who had undergone unilateral neck dissection with sparing of the accessory nerve, SCM and internal jugular vein, were included. The response rates (%), cVEMPs parameters such as the prestimulus background EMG [Root mean square (RMS)] activity (μV), P13 and N23 peak latencies (ms), interpeak (N23-P13) interval (ms), scale and non-scale interpeak (N23-P13) amplitudes (μV) were compared between the groups. Amplitude asymmetry ratio (AAR) was calculated.

RESULTS: Twenty patients (14 males and 6 females), age was between 38 and 79 years were included in the study. All of the patients had clear cVEMPs on the NOS, whereas 18/20 (90%) patients had on the NDS. P13 and N23 peak latency of the NDS were found to be significantly longer than the NOS (P = 0.01). There was no significant difference in N23-P13 interpeak interval between two sides (P > 0.05). There was a negative correlation between P13 peak latency and post-operative time (P = 0.042; R = ‑0.484). Scale and non-scale N23-P13 interpeak amplitudes of the NDS were found to be significantly lower than the NOS (P = 0.03). Mean AAR was found as 0.28 ± 0.16 (0.08-0.76). Seven patients (35%) had abnormal amplitude asymmetry. RMS values, were statistically and significantly lower in NDS compared to NOS (P = 0.01). However, no correlation was observed between the RMS values and peak latency and peak amplitude values (P > 0.05).

CONCLUSIONS: cVEMP testing is an easy-to-apply, non-invasive, painless, and recordable test that can be used for evaluations of SAN and SCM function for patients undergoing neck dissection. After neck dissection, VEMP abnormalities can be detected. However, further studies are needed to indicate whether these abnormalities originate within the vestibular system and are due to pathologies originating from the SANs and SCMs. In addition, preoperative and postoperative studies are needed to better guide the clinical application of cVEMP testing.