Eight patients in the migraine group (7, 18.4 % unilateral; 1, 2.6 % bilateral) demonstrated absent oVEMP responses, while responses could not be obtained for three patients in the TTH group (2, 6.7 % unilateral; 1, 3.3 % bilateral) and five patients in the control group (3, 6.0 % unilateral; 2, 4.0 % bilateral). A low response rate was observed in migraineurs, but no statistical difference was detected in the response rate of oVEMP among groups (Table 2). In oVEMP, the migraine group had mean latencies of bilateral n1 and left p1 significantly longer than the other groups (p < 0.05). Mean amplitudes of n1-p1 were lower than in the other groups, but the difference did not reach statistical significance (Table 3). No significant difference was observed in the AR amplitude or interaural latency differences of oVEMP. Illustrated examples of oVEMP tracings in controls and patients with migraine are shown in Fig. 1. Box plots of statistically significant oVEMP parameters are shown in Fig. 2.
Table 2 VEMP response rates in headache patients and healthy controls
TTH (n = 30) Migraine (n = 38) Controls (n = 50)
oVEMP
Bilateral response, n (%) 27 (90.0 %) 30 (78.9 %) 45 (90.0 %)
Unilateral response, n (%) 2 (6.7 %) 7 (18.4 %) 3 (6.0 %)
No response, n (%) 1 (3.3 %) 1 (2.6 %) 2 (4.0 %)
cVEMP
Bilateral response, n (%) 23 (76.7 %) 34 (89.5 %) 46 (92.0 %)
Unilateral response, n (%) 7 (23.3 %) 4 (10.5 %) 3 (6.0 %)
No response, n (%) 0 (0 %) 0 (0 %) 1 (2.0 %)
TTH tension-type headache, oVEMP ocular vestibular evoked myogenic potential, cVEMP cervical vestibular evoked myogenic potential
Table 3 oVEMP results of headache patients and healthy controls
Parameters TTH Migraine Controls
Left side
latency n1 (ms) 11.29 ± 0.78** 12.34 ± 1.43*,** 11.29 ± 0.73*
latency p1 (ms) 16.09 ± 0.83 17.05 ± 1.95* 16.11 ± 0.82*
n1-p1 interpeak latency (ms) 4.79 ± 0.87 4.75 ± 1.22 4.82 ± 0.92
n1-p1 amplitude 11.64 ± 6.73 8.00 ± 5.21+ 11.66 ± 9.14
Right side
latency n1 (ms) 11.42 ± 0.86** 12.41 ± 1.41*,** 11.58 ± 0.90*
latency p1 (ms) 16.41 ± 0.89 16.99 ± 2.02 16.20 ± 1.04
n1-p1 interpeak latency (ms) 4.99 ± 1.02 4.58 ± 1.24 4.62 ± 1.00
n1-p1 amplitude 11.29 ± 6.77 7.51 ± 4.47+ 11.76 ± 10.79
Interside difference
interaural latency diff., n1 0.64 ± 0.86 0.91 ± 0.97 0.74 ± 0.72
interaural latency diff., p1 0.64 ± 0.55 0.84 ± 0.95 0.78 ± 0.62
amp. asymmetry ratio, n1 0.23 ± 0.17 0.28 ± 0.17 0.23 ± 0.16
amp. asymmetry ratio, n1 0.22 ± 0.19 0.28 ± 0.21 0.24 ± 0.15
*p < 0.05, statistically significant between patients with migraine and controls; **p < 0.05, statistically significant between patients with migraine and patients with TTH; values are expressed as the means ± standard deviation
TTH tension-type headache, oVEMP ocular vestibular-evoked myogenic potential, amp amplitude
Fig. 1 oVEMP and rectified cVEMP responses in normal subjects (a-1, b-1, respectively) and migraine patients (a-2, b-2, respectively). oVEMP: ocular vestibular evoked myogenic potential; cVEMP: cervical vestibular evoked myogenic potential
Fig. 2 Box plots of latency of oVEMP. Latencies of a left n1, b left p1, and c right n1. Horizontal dashed lines indicate the grand average. *p < 0.05, statistically significant difference between migraine patients and healthy controls; † p < 0.05, statistically significant difference between migraine patients and patients with TTH; oVEMP: ocular vestibular evoked myogenic potential