Case report

A 50-year-old male with no significant medical problems, exhibiting partial edentulism in the upper maxilla and bone resorption of the latter, resulting in a poor aesthetic appearance ( Fig. 1 ) was scheduled for OSFE with simultaneous implant placement. The osteotomy was initiated with a piezoelectric device, followed by a 2 mm twist drill drilling to 1 mm short of the sinus floor. Percussion with the lesser diameter osteotome was then applied until the cortical sinus floor was fractured. Insertion and removal of osteotomes was performed in a straight path with light malleting. A 3.5 mm diameter, 11 mm long implant was successfully placed in site 1.6. Two more 3.5 mm diameter, 11 mm long implants were successfully inserted with conventional drill technique in sites 1.4 and 1.1. The surgery lasted 80 min. Immediately after recovery from the anaesthetic, the patient experienced intense vertigo accompanied by nausea. He had no previous history of dizziness, so an anti-vertigo drug was prescribed (betahistine 8 mg 2 times a day for 2 days after surgery) to manage his symptoms. The symptoms persisted on the day after surgery so the patient was referred to an ear, nose and throat (ENT) specialist. After evaluating his history and clinical examination a prompt diagnosis was made of BPPV associated with cupulolithiasis of the right posterior semicircular canal. The patient was successfully treated using Epley’s manoeuvre. He reported complete resolution of his vertigo and nausea during a follow-up examination on the next day. The anti-vertigo drug therapy was stopped. A Dix–Hallpike test was performed and judged to be negative because nystagmus was not observed and there were no reports of vertigo or nausea. The patient was evaluated weekly for 1 month and he continued to report complete resolution of all symptoms.

Postoperative radiograph. Note the presence of fractured bone fragments and the elevation of the sinus membrane.

Discussion

The installation of oral implants in the maxillary premolar or first molar region using OSFE is an ideal replacement of strategically important abutments and may help to avoid less comfortable removable appliances or the use of extension bridges with increased risks of technical failures.

BPPV has been reported as a postoperative complication following OSFE. Unlike the high incidence of perforation of the Schneiderian membrane, the incidence of OSFE-related BPPV is less than 3% (4 in 146 patients). Symptoms of BPPV include brief attacks of vertigo and nausea that are provoked by angular position changes of the head. Symptoms resolve within several days to weeks or may persist chronically. Dix and Hallpike introduced the term ‘benign paroxysmal positional vertigo’ and described the Dix–Hallpike manoeuvre and criteria for diagnosing BPPV.

Schuknecht theorized that BPPV is triggered by relatively heavy debris, from degenerating otoconia of the utricular macula, settling on the cupula of posterior semicircular canal (cupulolithiasis). The posterior semicircular canal is the area most commonly involved in the pathogenesis of BPPV, probably because it is located at the most dependent position in the vestibular apparatus in an upright person. If debris dislodges, it will tend to fall to the back and bottom of the system where the posterior semicircular canal is located.

Diagnosis is a problem because a variety of clinical syndromes are diagnosed as BPPV, and numerous entities present with vertigo induced by changes in position or resemble a BPPV. The diagnosis of BPPV is made by observing the classic eye movements in association with a through evaluation of the patient’s medical history (e.g. associated symptoms and their duration, previous surgical interventions, history of infections or trauma, and medications).

The Dix–Hallpike test confirms the diagnosis. The test is performed by moving the patient rapidly from a sitting position to a position with the head-hanging 45° below the horizontal, with each ear alternately undermost. A positive result is considered a burst of vertigo accompanied by characteristic nystagmus, which is typical of stimulation of the posterior semicircular canal.

Various treatments have been proposed for BPPV, including drugs, surgery and vestibular rehabilitation exercises. The primary management includes manoeuvres to reposition the debris into the utricule so that there is no abnormal manifestation of the vestibule-ocular reflexes when the position of the head is changed.

In 1992, Epley introduced the canalith repositioning procedure based on the theory of canalolithiasis. The procedure begins with the patient sitting on the examination table with his head turned 45° to the affected ear. The patient’s body is quickly brought backwards into a slight head-hanging position, keeping the head turned to the same side. The next stage includes rotating the head slowly towards the unaffected ear, which is now undermost. The patient is rolled to a side-lying position with the head turned 45° towards the same (unaffected) ear and downward to the floor. The patient is brought slowly back to the sitting position. The result of Epley’s manoeuvre is that otoconia moves through the posterior and anterior semicircular canal and finally enters the utricular cavity, where it becomes harmless. After the canalith repositioning procedure the patient is advised to not lie back, bend over or tilt the head for the next 2 days. The patient must sleep in a slightly elevated position and avoid turning towards the affected ear during sleep.

Numerous conditions have been associated with BPPV (secondary BPPV), including head and neck trauma, post surgery (e.g. stapedectomy, cochlear implantation, osteotome maxillary sinus lift, molar teeth extraction, vestibular neuronitis, prolonged bed rest, infections, insufficiency and tumours). BPPV is a more common finding, than previously thought, following head trauma, and there is general consensus that the vestibular system should be included in the examination process.

Surgical trauma, specifically the pressure exerted by the osteotomes, determines the detachment of the otoliths from the utricular macula. The patient’s head position, hyperextended and tilted opposite to the side on which the surgeon is working, favours the entry of free-floating particles into the posterior semicircular canal of the implanted site.

To understand the pathodynamics of iatrogenic osteotome-related BPPV the authors think it is necessary to be familiar with the skull stress trajectories in the maxilla and zygoma. Several techniques have been used to study the stress trajectories of the facial skeleton. The photoelastic technique showed that in an experimental situation there are 3 main stress trajectories in the face: the maxillo-nasal, the maxillo-zygomatic, and the maxillo-pterygoid. The application of external loads by means of osteotomes produces stresses in the alveolar and maxillary regions. In the area of the premolar and molars, the trajectories follow a parallel direction with the roots of these teeth. Stresses are uniformly distributed on both sides of the zygomatico-maxillary suture.

The more likely pathophysiological mechanism is represented by an indirect trauma of the posterior labyrinth due to the use of osteotomes on bony structures in relation to the close proximity to the temporal bone. This possibility leads to the hypothesis that BPPV is a possible, although not frequent, complication of surgical interventions, such as dental or maxillofacial surgery.

Vibration would propagate through the maxillo-zygomatic stress trajectory, up to the posterior labyrinth. At this level, mechanical energy would be transferred to the endolymphatic liquid, resulting in macular trauma able to determine the otoconial separation. Another hypothesis considers the tilting of the head during oral-maxillofacial surgery. It is possible to hypothesize that the surgical traumatic event acts as a triggering factor on a pre-existing substratum.

In patient with antecedents of BPPV, the use of OSFE is not advised. To avoid BPPV, the patient is advised to get up slowly after surgery, and excessive tapping with the mallet during surgery should be avoided.

BPPV is self-limiting and the symptoms often subside or disappear within 6 months of onset. Although the symptoms tend to wax and wane, they are incapacitating when present. The nausea may prevent the patient from performing daily activities. Motion sickness medications are sometimes helpful in controlling the nausea but are generally not beneficial.

The canalith repositioning procedure is very effective in treating the problem. The implant surgeon should be aware of BPPV and take complaints of dizziness following OSFE, very seriously. In current clinical practice, the incidence of BPPV secondary to OSFE is underestimated because BPPV is a self-limiting disease with spontaneous (within 1 month) recovery for which an otoneurological evaluation is not usually performed.

Indications for the use of OSFE should be considered critically regarding bone quality and quantity. Taking the patient’s history, to assess possible risk factors for BPPV, should be considered in the indication for, and planning of, implant site preparation with osteotomes. BPPV should be considered in all patients with postoperative positional vertigo, particularly after OSFE. The oral and maxillofacial surgeon should be able to recognize this common clinical entity and promptly refer the patient to an ENT specialist to guarantee early diagnosis and treatment. This will lessen the risk of long-lasting postoperative symptoms linked to BPPV, providing relief for the patient and maintaining a good medico-legal guarantee for the surgeon.

The usual age of onset of BPPV is 50–60 years; the incidence increasing with age. The authors think that the increasing use of implant bed preparation procedures involving osteotomes and surgical mallet percussion, particularly among middle-aged patient and the elderly, will increase the incidence of this post-surgical complication. The risk of postoperative vertigo should be always mentioned when obtaining informed consent for an OSFE procedure.