The subjective visual horizontal after stapedotomy: evidence for an increased resting activity in otolithic afferents

Positive and negative post stapedotomy effects on cervical VEMP recordings; a STROBE analysis

AIMS

The primary goal of the present study was to compare the pre- and post-stapedotomy elicitation and waveform characteristics of both air- and bone-conduction (AC-, BC-) cervical vestibular evoked myogenic potentials (cVEMPs) through an individualized approach. A possible association between audiological characteristics, such as AC- and BC- pure tone audiometry thresholds and air-bone gap and the production of cVEMPs before and after stapedotomy was also investigated.

MATERIAL AND METHODS

Twenty-five ears were subjected to full audiological evaluation as well as AC- and BC-cVEMPs pre- and post-stapedotomy. Four subgroups were studied; consistently present/absent, post-operatively disappeared and restored cVEMPs.

RESULTS

Post-stapedotomy changes in cVEMP elicitability did not reach significance for either AC-cVEMP (OR=5.41, 95% CI 0.88-33.36, P=0.06) or BC-cVEMP (OR=2.40, 95% CI 0.42-13.60, P=0.3). Normal or abnormal AC-cVEMPs were equally subject to post-operative changes (OR=1.95, 95% CI 0.32-12.01, P=0.5), as were BC-cVEMPs (OR=3.75, 95% CI 0.66-21.25, P=0.1). Neither the audiological characteristics nor the surgical outcome, in terms of ABG results, were relevant to the presence or absence of AC- and BC-cVEMPs before or after stapedotomy.

CONCLUSIONS

The presumed changes brought to the sacculus by stapedotomy are minor and beyond the diagnostic abilities of either AC-cVEMPs or BC-cVEMPs, both in terms of cVEMPs elicitability and waveform characteristics. In individual cases, however, which may deserve further investigation, cVEMPs may reappear or disappear after stapedotomy probably following minor changes toward a lower or higher vestibular system resistance for pressure and sound transmission.

Cochlear implant surgery and perioperative dizziness is associated with utricular hyperfunction

BACKGROUND

Dizziness is a common perioperative complication after cochlear implantation (CI). To date, the exact cause behind this phenomenon remains unclear. There is recent evidence to suggest that otolith function, specifically utricular, may be affected shortly after CI surgery, however whether these changes are related to patient symptoms has not yet been investigated.

OBJECTIVE

To determine whether CI surgery and perioperative dizziness is associated with changes on utricular function.

METHODS

We performed an observational study on patients undergoing routine CI surgery. Utricular function was assessed using the Subjective Visual Vertical (SVV), and perioperative dizziness was determined using a questionnaire. The study followed patients before surgery and then again 1-day, 1-week and 6-weeks after implantation.

RESULTS

Forty-one adult CI recipients participated in the study. The SVV deviated away from the operated ear by an average of 2.17° a day after implantation, 0.889° 1 week and -0.25° 6 weeks after surgery. Dizziness contributed to a tilt of 0.5° away from the implanted ear. These deviations were statistically significant.

CONCLUSIONS

CI surgery causes utricular hyperfunction in the operated ear that resolves over 6 weeks. SVV tilts were greater in participants experiencing dizziness, suggesting that utricular hyperfunction may contribute to the dizziness.

Contralesional subjective visual horizontal predicts endolymphatic hydrops

Background: The subjective visual horizontal (SVH) is a test of utricular function that assesses conjugate ocular torsion which is a component of the ocular tilt reaction (OTR). In unilateral destructive peripheral vestibular lesions, the OTR and so the SVH tilt is usually ipsiversive.Aims/objective: Our study aimed to profile the causes of a contraversive SVH tilt in patients with a confirmed unilateral peripheral vestibular deficit.Materials and methods: The clinical records, nystagmus and vestibular investigation characteristics of 52 patients with a unilateral canal paresis (CP) on caloric of ≥30%, a contraversive SVH tilt of ≥4 degrees and at least one pure tone audiometry were retrospectively analysed.Results: The most common diagnosis of patients (n = 39) with a contraversive SVH and ipsilesional CP was endolymphatic hydrops: 35 (67.3%) had Meniere's disease (MD) and 4 (7.7%) had delayed endolymphatic hydrops (DEH). The remaining 13 (25%) of cases had other peripheral aetiologies or an unknown diagnosis. 16 (30.8%) patients had ictal spontaneous nystagmus at the time of SVH or caloric testing.Conclusions and significance: A contraversive SVH with unilateral CP suggests endolymphatic hydrops.

Revision surgery for otosclerosis: An overview

Stapes surgery for otosclerosis has been proved to be a very satisfying procedure. However, the condition is difficult for the patients with no or little hearing gain after surgery and for those who had sudden or gradual hearing loss after a successful air-bone gap closure in the follow-up period. The issue of re-exploring the middle ear is challenging. A general review of this subject from several points of view remains lacking. In this study, articles related with the revision surgery for otosclerosis have been reviewed after a PubMed research and common and/or contradictory points were documented. The aim of this study is to give an insight to diagnostic and therapeutic approaches for the clinicians in patients who need a revision surgery. In conclusion, prosthesis problems, loose prosthesis in stapedotomy and migrated prosthesis in stapedectomy are the most common causes for revision surgery. Most important indicators which effect better hearing outcome following revision surgery are those ears with the presence of incus, with no obliteration of oval window, with small fenestra stapedotomy and the experience of surgeon. The risk of neurosensorial hearing loss in revision cases is not high but the hearing gain is limited as compared to primary cases. The rate of 10 dB air-bone gap closure is around 60%-70% at most and even less promising results have been reported. Patient’s demands and expectations have to be clarified in a realistic way.

Surgery of the ear and the lateral skull base: pitfalls and complications

Surgery of the ear and the lateral skull base is a fascinating, yet challenging field in otorhinolaryngology. A thorough knowledge of the associated complications and pitfalls is indispensable for the surgeon, not only to provide the best possible care to his patients, but also to further improve his surgical skills. Following a summary about general aspects in pre-, intra-and postoperative care of patients with disorders of the ear/lateral skull base, this article covers the most common pitfalls and complications in stapes surgery, cochlear implantation and surgery of vestibular schwannomas and jugulotympanal paragangliomas. Based on these exemplary procedures, basic "dos and don'ts" of skull base surgery are explained, which the reader can easily transfer to other disorders. Special emphasis is laid on functional aspects, such as hearing, balance and facial nerve function. Furthermore, the topics of infection, bleeding, skull base defects, quality of life and indication for revision surgery are discussed. An open communication about complications and pitfalls in ear/lateral skull base surgery among surgeons is a prerequisite for the further advancement of this fascinating field in ENT surgery. This article is meant to be a contribution to this process.

Immediate postoperative nystagmus and vestibular symptoms after stapes surgery

CONCLUSION

Vestibular disturbance is frequent, but mild even immediately after stapes surgery. Vestibular symptoms improved or disappeared quickly, and they did not correlate with nystagmus. Outpatient stapes surgery performed under local anaesthesia is a feasible approach.

OBJECTIVE

Vestibular symptoms are common and may prevent outpatient surgery. The time course of vestibular disturbance is unclear, and we aimed to evaluate it immediately after the operation in the recovery room.

METHODS

Twenty patients with otosclerosis undergoing stapedotomy were prospectively included in the study. Postoperative symptoms were collected and nystagmus was recorded with video-oculography (VOG) on average 29 min after the surgery.

RESULTS

None of the patients had spontaneous nystagmus with gaze fixation. Nine patients (45%) had slow spontaneous horizontal nystagmus (mean slow phase velocity of 1.1°/s) in the primary position without gaze fixation. In seven of these, the nystagmus obeyed Alexander's law. Nine patients (45%) had vestibular symptoms at the end of the surgery, and four patients at the time of VOG recording. Vertigo was experienced immediately after the operation in five, floating sensation in two, and unspecific dizziness in two patients. Vestibular symptoms were mild or moderate in most patients. The occurrence of nystagmus did not correlate with vestibular symptoms (p > 0.05).

Subjective visual vertical in patients with ear surgery

CONCLUSION

Dysequilibrium is one of the most important side effects of ear surgery. The subjective visual vertical can be used as a good indicator for the evaluation of otolithic function in patients with ear surgery.

OBJECTIVE

To investigate the influence of various types of ear surgery on the otolithic organs.

METHODS

Seventy-one patients underwent ear surgery. Subjective visual vertical (SVV) test was performed before and after ear surgery. We investigated the directional changes of SVV before and after the ear surgery.

RESULTS

The postoperative SVV of two patients who underwent translabyrinthine removal of vestibular schwannoma shifted toward the operated side, but following other surgical procedures the SVV tended to shift toward the healthy side.

Perioperative Recordings of Vestibular-Evoked Myogenic Potentials in Otosclerosis

OBJECTIVES

The aim of the present study was to investigate saccular function in patients with otosclerosis. Furthermore, the influence of stapedotomy on the vestibular-evoked myogenic potentials (VEMPs) should be demonstrated.

STUDY DESIGN

Prospective study.

SETTING

Tertiary referral center.

METHODS

Bone-conducted tone-burst-evoked VEMPs were measured in 23 patients (25 ears) with unilateral or bilateral otosclerosis preoperatively and postoperatively.

RESULTS

Preoperatively, VEMPs could be recorded in 11 ears (44%). There was no statistically significant correlation among the extent of preoperative sensorineural hearing loss, age, and VEMP measurements. Postoperatively, VEMPs were found in 14 ears (56%). In three cases (12%), VEMPs reappeared after surgery. The rare cases of preoperative vertigo could not be correlated to the nonappearance of VEMPs.

CONCLUSION

Stapedotomy surgery does not influence VEMPs, implying that the saccular receptors are not injured by surgery. Moreover, in some cases, the elicitability of VEMPs was improved by stapedotomy surgery. Seemingly, otosclerosis can influence the generation of VEMPs most probably due to an involvement of the otolith organ's saccular receptors. No correlation was found between the clinical occurrence of vertigo and the elicitability of VEMPs.

Video-oculography findings in patients with otosclerosis

OBJECTIVE

To evaluate the existence of vestibular irritation with video-oculography before and after stapes surgery and to examine whether there would be signs of specific end-organ irritation.

STUDY DESIGN

A prospective study of preoperative and postoperative nystagmus, vertigo, and hearing thresholds.

SETTING

University hospital, tertiary referral center.

PATIENTS

Thirty-three patients (mean age, 47 yr) with otosclerosis.

INTERVENTION

Stapedotomy/stapedectomy with laser or microdrill.

MAIN OUTCOME MEASURES

Spontaneous, gaze-evoked, and head-shaking nystagmus was measured preoperatively and approximately 1 week, 1 month, and 3 months after the operation. Three dimensions of nystagmus were identified and their slow-phase velocities were calculated.

RESULTS

Spontaneous horizontal nystagmus was found preoperatively in 18% (slow-phase velocities, 1.3-3.3 deg/s) and postoperatively in 11 to 19% of the patients (slow-phase velocities, 1.3-3.8 deg/s). Head-shaking nystagmus was not detected preoperatively. After the operation, 11 to 15% of the patients had head-shaking nystagmus (slow-phase velocities, 6.6-17.8 deg/s), but this prevalence did not differ statistically significantly from the preoperative level (p = 0.18). Vertical nystagmus was found equally pre- and postoperatively. Torsional nystagmus was not found. One week after the operation, nine patients (27%) had some sensation of vertigo, but it lasted over 1 month in only one patient. We found no significant correlation with vertigo and the types of nystagmus.

CONCLUSION

Nystagmus with a low slow-phase velocity can occur in patients with otosclerosis. However, according to the video-oculographic findings and subjective symptoms, significant vestibular dysfunction seems to be rare and temporary after stapes surgery.

Head-body righting reflex from the supine position and preparatory eye movements

CONCLUSION

Saccular and utricular maculae can provide information on the supine static position, considering that both have pronounced curved structures with hair cells having a variety of polarization vectors that enable them to sense an inverted position and thus direct the righting reflex.

OBJECTIVE

The vestibular system is essential for the structuring of motor behaviour, senses linear and angular acceleration and has a strong influence on posture and balance at rest, during locomotion and in head body righting reflexes.

MATERIAL AND METHODS

Using guinea pigs in the supine position with a symmetrical head and trunk position, the ocular position was analysed to ascertain whether any ocular movement that occurred would adopt a spatial deviation indicative of the subsequent head and body righting. The characteristics of the righting reflex (direction, latency, duration and velocity) were analysed in guinea pigs from position signals obtained from search coils implanted in the eye, head and pelvis. The animals were kept in a supine position for a few seconds or even minutes with the eyes in a stable primary position and the head and body symmetrical and immobile.

RESULTS

The righting reflex took place either immediately or after a slow deviation of the eyes. In both cases the righting sequence (eyes, head, body) was stereotyped and consistent. The direction of head and body righting was along the longitudinal axis of the animal and was either clockwise or anticlockwise and the direction of righting was related to the direction of the eye deviation. The ocular deviation and the direction of deviation that initiated and determined the direction of the righting reflex could be explained by possible otolithic activation.

Benign paroxysmal positional vertigo after stapedectomy

OBJECTIVE

To determine the incidence of benign paroxysmal positional vertigo (BPPV) following stapedectomy in a patient group and the efficacy of the Epley maneuver in this group.

STUDY DESIGN

Prospective study in a university-based tertiary referral system.

METHODS

The patient group comprised 63 patients who had undergone stapedectomy; a control group consisted of normal healthy individuals with no otolaryngological complaints. All individuals underwent the Dix-Hallpike maneuver for the diagnosis of BPPV. Patients who exhibited vertigo, torsional nystagmus (which reverses its direction on return to sitting position) preceded by a latent period, and the fatigability of these findings were considered to have BPPV. If the test result was positive, they underwent the Epley therapeutic maneuver.

RESULTS

Four of the patients who had undergone a stapedectomy showed characteristic findings of BPPV. No individual in the control group had BPPV. All patients responded well to the Epley maneuver.

CONCLUSIONS

Stapedectomy may be regarded as an etiological factor in BPPV. Because the fenestra is located in the posterior part of the stapes footplate, the pathophysiology appears to be related to utricular rather than saccular trauma. Correct measurement of the distance between the incus and stapes footplate is essential in stapedectomy. An Internet survey of the relevant literature in English shows a scarcity of publications on the incidence of BPPV following stapedectomy. In the present study, 63 patients who had undergone a stapedectomy were investigated for the presence of BPPV; all had Dix-Hallpike maneuvers performed for the diagnosis. Sixty-three individuals with no otolaryngological complaints made up the control group. Four of the patients who had undergone stapedectomy showed characteristic findings of BPPV, and no individual in the control group had BPPV; the difference between the two groups was statistically significant. All four of the patients diagnosed with BPPV responded well to the Epley maneuver. The pathophysiology appears to be related to utricular trauma. Correct measurement of the distance between the incus and stapes footplate is essential in stapedectomy.

Assessing otolith function by the subjective visual vertical

The effects of peripheral vestibular diseases on the subjective visual vertical (SVV) are resumed and provide the basis for some insights into the otolith pathophysiology. With a normal range of 0 +/- 2 deg (when measured in an upright body position), the SVV was shifted by 11 +/- 6 deg toward the ipsilateral ear in 40 patients following an acute unilateral vestibular deafferentiation (UVD), but in the opposite direction in 9 of 52 patients after stapes surgery. These opposite effects suggest a push-pull mechanism of the pairs of otolith organs with respect to the SVV. The dissociation between the SVV and the perception of body position indicates influences by unconscious reflexive mechanisms such as ocular cyclotorsion on the SVV. In chronic UVD patients, lateral shifts of the subjects during constant angular velocity rotation into various eccentric positions (+/- 16 cm) revealed a shift of the "center of graviception" close to the remaining intact contralateral inner ear. To date, this seems to be the most consistent test for clinical identification of a chronic compensated unilateral loss of otolith function. The findings regarding asymmetries in otolithic sensitivity to medially and laterally directed roll-tilts remain controversial, probably mainly because of influences of extravestibular cues.