Abstract
The Le Fort I osteotomy is widely used to correct dentofacial deformities. Benign paroxysmal positional vertigo (BPPV) is a common vestibular end organ disorder characterized by short, often recurrent episodes of vertigo. Head trauma is one of the known causes of BPPV. During pterygoid osteotomy, the surgical trauma induced by percussion with the surgical mallet and osteotomes can displace otoliths into the semicircular canal, resulting in BPPV. The aim of this study was to evaluate the potential risk of occurrence of BPPV in individuals undergoing Le Fort I osteotomy. Twenty-three patients were included in this study. The Dix–Hallpike manoeuvre, positional tests using electronystagmography, and vestibular evoked myogenic potential (VEMP) tests were performed 1 week before surgery (T0), 1 week after surgery (T1), and 1 month after surgery (T2). The results were compared statistically. BPPV was observed in three patients. Eleven patients had nystagmus at the T1 evaluation and seven at the T2 evaluation. The difference between the T0 and T1 time points was statistically significant ( P = 0.001). BPPV is a possible complication of Le Fort I osteotomy. Surgeons should be aware of this complication, and the diagnosis of BPPV should be considered in patients who have undergone Le Fort I osteotomy.
Patients with dentofacial deformities, such as congenital and acquired abnormal positioning of the maxilla, mandible, or both, can experience problems with facial aesthetics, mastication, and speech. The correction of midfacial deformities often involves Le Fort I osteotomy with advancement, impaction, or a combination of these movements.
The Le Fort I osteotomy involves surgical trauma induced by percussion with the surgical mallet and osteotomes, along with hyperextension of the neck. It has been shown that this surgical trauma can promote different types of ear problems, such as decreased hearing sensitivity, middle ear pressure, and auditory function, because of the close relationship between the ear and the sphenoid bone.
Benign paroxysmal positional vertigo (BPPV) is a common vestibular end organ disorder characterized by short, often recurrent, episodes of vertigo that are triggered by certain head movements in the plane of the semicircular canals. BPPV occurs in 15–20% of head trauma cases and is rarely reported after maxillofacial surgery.
There are two pathophysiological mechanisms in BPPV: cupulolithiasis and canalithiasis. In cupulolithiasis, otoconial debris in the semicircular canal becomes attached to the cupula and the patient is rendered sensitive to gravity. In canalithiasis, calcium crystals, called otoliths, dislodge from the utricle of the inner ear and move within the lumen of the semicircular canals. When these otoliths move within the canal, they cause endolymph motion during the angular acceleration of the head that stimulates the affected canal, thereby causing vertigo.
There are a few case reports and case series published in the literature concerning BPPV after dental and maxillofacial surgical procedures, such as impacted third molar removal, osteotome techniques for sinus floor elevation, alveolar augmentation by ridge splitting, and septorhinoplasty. There is only one clinical study suggesting that BPPV should be considered in patients who have undergone Le Fort I osteotomy, and knowledge about this complication following orthognathic surgery is still limited. The aims of this prospective study were to comprehensively evaluate the potential risk of occurrence of BPPV in individuals undergoing Le Fort I osteotomy and to compare the results of maxillary advancement and/or impaction procedures.
Patients and methods
This study was approved by the institutional review board and ethics committee of the university. Written informed consent was obtained from all subjects.
This prospective study was conducted between December 2011 and December 2014 in the department of oral and maxillofacial surgery of a university hospital in Istanbul, Turkey. A total of 23 consecutive patients (12 female and 11 male), ranging in age from 18 to 32 years, were included.
All of the patients included were ASA I status according to the American Society of Anesthesiology (ASA) health status classification. Nasotracheal intubations were performed by the same anaesthesiologist using the same agent. The study patients underwent conventional Le Fort I osteotomy, and the pterygomaxillary dysjunction was performed with a reciprocating saw and curved osteotomes by the same surgical team. Postsurgical medication was standard for all subjects. Exclusion criteria were listed as having had a previous ear operation or ear anomaly, a history of BPPV, neurological disorders, orthognathic surgery, maxillofacial deformity, and failure to attend postoperative evaluation appointments.
Electronystagmography (ENG) with the Dix–Hallpike manoeuvre, positional tests, and vestibular evoked myogenic potential (VEMP) tests were performed 1 week before surgery (T0), 1 week after surgery (T1), and 1 month after surgery (T2) in the department of otorhinolaryngology, division of neuro-otology of the study university. All test results were evaluated by the senior author of this paper from the neuro-otology department (L.N.O.), who was blinded to the patient identities. The surgical procedure used was Le Fort I osteotomy with advancement ( n = 11) or a combination of advancement and impaction ( n = 12), with or without mandibular surgeries.
For the Dix–Hallpike manoeuvre, the patient was asked to sit down, with the head turned approximately 45° to the right or left. The patient was then instructed to lie down in the dorsal decubitus position with the examiner holding their head. The head was kept at an approximately 30° extension. The diagnostic criteria included vertigo and the occurrence of characteristic mixed torsional and vertical nystagmus with the upper pole of the eye beating towards the dependent ear and vertical nystagmus beating towards the forehead.
For the positional test, the patient was asked to lie down in the dorsal decubitus position with the head flexed anteriorly by 30°. The patient was then instructed to turn the head to one side and keep it in that position for up to 1 min. The diagnostic criteria included provoked vertigo and horizontal nystagmus.
The VEMP test was performed with the patient in a sitting position with his or her chin turned over the contralateral shoulder, tensing the sternocleidomastoid muscle (SCM). Surface electromyographic activity was recorded with an evoked acoustic potential system (VEMP System, Eclipse preamplifier EPA 4V, Smart EP 15; Interacoustics a/s, Assens, Denmark). Active non-inverting recording electrodes were placed in the middle third part of the SCM. Reference electrodes were placed ipsilateral to the sternal manubrium region near the tendon of the SCM and a ground electrode was placed in the centre of the forehead. The VEMP responses were obtained by binaural acoustic stimulation and recorded from bilateral SCMs. Tone bursts at 500 Hz were delivered through an inserted earphone at a rate of 5.1/s for an average of 200 repetitions (500 Hz, 120 dB SPL hearing level intensity, stimulation rate 5.1/s). Electromyographic signals were amplified and band-pass filtered (range 10–1500 Hz). Electromyographic signals were recorded for 50 ms. Mean peak latencies (in milliseconds) of the two early waves (p13 and n23, recorded as P1 and N1, respectively) were measured on the side ipsilateral to the stimulation. Recordings were determined by averaging 200 stimuli, and two traces from each test were assessed to estimate reproducibility . Skin resistance was lower than 5 kΩ. The initial negative–positive biphasic waveform comprised peaks N1 and P1. The amplitudes of N1 and P1 at the maximal intensity of stimulation were analyzed in each evaluation.
Statistical analysis
Data were analyzed using IBM SPSS Statistics for Windows, version 21.0 (IBM Corp., Armonk, NY, USA). The results for the three evaluation time points (T0, T1, and T2) were compared statistically with repeated measures analysis of variance (ANOVA) and paired samples t -tests. The results for isolated maxillary advancement and concomitant maxillary impaction – advancement were also compared statistically using the Student t -test. Continuity (Yates) correction, Fisher’s exact test, the χ 2 test, and the McNemar test were used for the nominal data. All differences associated with a chance probability of 0.05 or less were considered statistically significant.
Results
The mean age of all included patients was 23 years. The mean amount of maxillary advancement was 5 mm and the mean amount of impaction was 1.5 mm. No complications were observed during the surgical procedures and no persistent BPPV occurred in any of the study patients.
BPPV was diagnosed in three out of the 23 patients. Regarding the Dix–Hallpike manoeuvre and positional tests, 11 patients had nystagmus at the T1 evaluation and seven at the T2 evaluation. The difference between the T0 and T1 time points was statistically significant ( P = 0.001) ( Table 1 ).
When the patients who underwent isolated advancement were compared to those who underwent concomitant maxillary advancement and impaction, no statistically significant difference was observed at any of the evaluation time points ( Table 2 ).
| With impaction | Without impaction | P -value | |
|---|---|---|---|
| Nystagmus, n (%) | |||
| T0 | 0 (0%) | 0 (0%) | – |
| T1 | 8 (66.7%) | 3 (27.3%) | 0.141 a |
| T2 | 5 (41.7%) | 2 (18.2%) | 0.371 b |
| P -value c | |||
| T0–T1 | 0.008 ** | 0.250 | |
| T0–T2 | 0.063 | 0.500 | |
| T1–T2 | 0.375 | 1.000 | |
Regarding the P1 and N1 values of the VEMP tests for both the left and right ears of the patients, there were no statistically significant differences between the evaluation time points ( Table 3 ). For concomitant advancement-impaction patients P1 and N1 values of the left ears are statistically significant at T1 point. The differences between T0–T1 and T1–T2 of right ears’ P1 values are also statistically significant for these patients. For the isolated maxillary advancement patients; the differences between T0–T1 and T0–T2 of left ears’ P1 values, and the differences between T0–T1 and T1–T2 of left ears’ N1 values are statistically significant. ( Tables 4 and 5 ).
| P1 right | P1 left | N1 right | N1 left | |
|---|---|---|---|---|
| Mean ± SD | Mean ± SD | Mean ± SD | Mean ± SD | |
| T0 | 15.42 ± 2.32 | 16.09 ± 2.22 | 24.15 ± 2.66 | 23.83 ± 2.78 |
| T1 | 16.31 ± 3.52 | 15.13 ± 3.18 | 24.73 ± 4.05 | 22.9 ± 3.05 |
| T2 | 15.38 ± 2.64 | 15.74 ± 2.38 | 23.97 ± 3.27 | 23.34 ± 3.03 |
| P -value a | 0.193 | 0.457 | 0.237 | 0.540 |
| P -value b | ||||
| T0–T1 | 0.256 | 0.239 | 0.488 | 0.261 |
| T0–T2 | 0.944 | 0.504 | 0.806 | 0.435 |
| T1–T2 | 0.067 | 0.225 | 0.087 | 0.442 |
| P1 right | With impaction Mean ± SD |
Without impaction Mean ± SD |
P -value a | P1 left | With impaction Mean ± SD |
Without impaction Mean ± SD |
P -value a |
|---|---|---|---|---|---|---|---|
| T0 | 14.86 ± 3.09 | 16.03 ± 0.75 | 0.227 | T0 | 15.70 ± 2.90 | 16.52 ± 1.12 | 0.388 |
| T1 | 17.36 ± 2.99 | 15.15 ± 3.83 | 0.136 | T1 | 16.39 ± 3.45 | 13.76 ± 2.29 | 0.045 * |
| T2 | 16.06 ± 2.79 | 14.64 ± 2.37 | 0.206 | T2 | 16.42 ± 2.78 | 15.01 ± 1.69 | 0.160 |
| P -value b | 0.011 * | 0.180 | P -value b | 0.589 | 0.048 * | ||
| P -value c | P -value c | ||||||
| T0–T1 | 0.011 * | 0.456 | T0–T1 | 0.532 | 0.015 * | ||
| T0–T2 | 0.230 | 0.070 | T0–T2 | 0.316 | 0.035 * | ||
| T1–T2 | 0.024 * | 0.561 | T1–T2 | 0.966 | 0.110 | ||
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