Vestibular Function In Patients Research Articles

Assessment of the audiovestibular system in patients with rheumatoid arthritis

ObjectiveThis study was designed to assess hearing and vestibular function in patients with rheumatoid arthritis (RA) in comparison with a control group. In addition, we correlated these findings in disease activity and severity.Materials and methodsTotally, 40 RA patients (35 women and five men) diagnosed according to the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria and 20 healthy controls (11 women and nine men), whose age ranged from 25 to 66 years with a mean age of 45.5±12.4 years, were included in the study. Each individuals was tested with pure tone audiometry. Mean values of air and bone conduction at each frequency and tympanometric values were calculated for the study groups. Videonystagmography (VNG) test including smooth pursuit, saccade, optokinetic tests, positioning tests, positional test, and water caloric tests was also carried out.ResultsThe mean air conduction threshold values at high frequencies (4000 and 8000 Hz) in the RA group were lower than in the control group. The difference between mean air conduction threshold values of the control group and the RA group at high frequencies was statistically significant (P<0.05). There was no statistically significance between the two groups as regards speech reception threshold, speech discrimination (DIS), and tympanometric values (P>0.05). VNG testing revealed central abnormalities in 12 (30%) patients, peripheral abnormalities in nine (22.5%) patients, and mixed abnormalities in one (2.5%) patient. There was no association between VNG abnormalities in patients with RA and age, sex, duration of disease, accompanying vertigo complaint, and the laboratory findings (P>0.05).ConclusionThere is an association between RA and audiovestibular system dysfunction regardless clinical and demographic situation of patients. We assume that the shearing and vestibular disturbances in RA are more prevalent than previously recognized. High-frequency hearing loss in RA patients could be an indicator of cochlear involvement.

Contrasting results of tests of peripheral vestibular function in patients with bilateral large vestibular aqueduct syndrome.

To analyze and summarize the effect of bilateral large vestibular aqueducts in peripheral vestibular organ function. Eighteen patients with bilateral large vestibular aqueduct syndrome (LVAS; Study Group) and 18 healthy volunteers (Control Group) were investigated using audiometry, caloric test, sensory organization test (SOT), and vestibular-evoked myogenic potential (VEMP) tests. All 18 patients (36 ears) exhibited sensorineural hearing loss. For cervical VEMP (cVEMP), the Study Group showed lower thresholds (Study Group vs. 71.4vs. 75.3dBnHL; p=0.006), N1 latencies (24.1vs. 25.2ms; p=0.026) and shorter P1 (15.3vs. 16.6ms; p=0.003), and higher amplitudes (400.7vs. 247.2µV; p<0.001) than the Control Group. For ocular VEMP (oVEMP), the Study Group had lower thresholds (79.3vs. 81.8dBnHL; p=0.046) and higher amplitudes (40.6vs. 14.4µV; p<0.001) than the Control Group. Fourteen of 16 patients (87.5%) who completed caloric tests had abnormal results, and 10 of 18 patients (55.6%) exhibited abnormal results in SOTs. The hyperfunction of vestibular test in otolithic organs and the hypofunction of vestibular test in semicircular canals, as well as the dysfunction in the balance test were demonstrated in patients with LVAS. Our findings can help clinicians gain a better understanding of the characteristics of vestibular organ function in patients with LVAS, which can facilitate optimal targeted treatment.

The vestibular implant: A probe in orbit around the human balance system.

The primary goal of the vestibular implant is to restore the vestibular function in patients with a disabling bilateral vestibular loss for whom there is currently no available treatment. The prototype developed by our team is a hybrid system consisting of a modified cochlear implant incorporating additional vestibular electrodes. Therefore, in addition of delivering sound information it is also capable of delivering motion information to the central nervous system using electrical stimulation. To date, thirteen patients have been implanted with such vestibular implant prototypes. For ethical reasons, only deaf ears were implanted and all patients experienced a clinical benefit from the hearing rehabilitation. The recent demonstration of partial restoration of the vestibulo-ocular and the vestibulo-collic reflexes in implanted patients suggests that gaze stabilization and postural control, fundamental functions of the balance system, can be artificially restored using a vestibular implant. This allows us to glimpse a useful clinical application in a near future. In parallel, we show how the vestibular implant provides a unique opportunity to explore the integration of the vestibular sensory input into the multisensory, multimodal balance system in humans, since it is able to selectively stimulate the vestibular system.

Noisy galvanic vestibular stimulation: an emerging treatment option for bilateral vestibulopathy.

Patients with bilateral vestibulopathy (BVP) suffer from persistent imbalance during standing and walking as well as an impaired gaze stabilization during head movements. Disabilities associated with BVP severely compromise patients' daily activities and are often linked to an increased risk of falls. Currently, the only established treatment option in BVP is physical therapy. However, treatment effects of physical therapy in BVP are most often limited and many patients do not adequately recover performance. Therefore, a number of technical therapeutic approaches are being explored that either try to substitute lost vestibular sensation with a congruent stimulation of other sense modalities or to artificially mimic vestibular function by means of an implantable vestibular prosthesis. Besides, attempts have recently been made to augment and optimize residual vestibular function in patients with BVP using an imperceptible noisy galvanic vestibular stimulation (nGVS). This approach is based on the natural phenomenon of stochastic resonance, wherein the signal processing in sensory systems can be improved by adding an appropriate level of noise to the system. Promising first study outcomes of nGVS treatment in patients with BVP indicate the feasibility of a future non-invasive sensory prosthetic device for BVP rehabilitation. This paper gives an overview about recent research on nGVS treatment in patients with BVP and discusses future research perspectives in this field.

Assessment of balance and vestibular functions in patients with idiopathic sudden sensorineural hearing loss.

This study investigated the relationship among the severity of hearing impairment, vestibular function and balance function in patients with idiopathic sudden sensorineural hearing loss (ISSNHL). A total of 35 ISSNHL patients (including 21 patients with vertigo) were enrolled. All of the patients underwent audiometry, sensory organization test (SOT), caloric test, cervical vestibular-evoked myogenic potential (cVEMP) test and ocular vestibular-evoked myogenic potential (oVEMP) test. Significant relationship was found between vertigo and hearing loss grade (P=0.009), and between SOT VEST grade and hearing loss grade (P=0.001). The abnormal rate of oVEMP test was the highest, followed by the abnormal rates of caloric and cVEMP tests, not only in patients with vertigo but also in those without vertigo. The vestibular end organs were more susceptible to damage in patients with vertigo (compared with patients without vertigo). Significant relationship was found between presence of vertigo and SOT VEST grade (P=0.010). We demonstrated that vestibular end organs may be impaired not only in patients with vertigo but also in patients without vertigo. The cochlear and vestibular impairment could be more serious in patients with vertigo than in those without vertigo. Vertigo does not necessarily bear a causal relationship with the impairment of the vestibular end organs. SOT VEST grade could be used to reflect the presence of vertigo state in the ISSNHL patients. Apart from audiometry, the function of peripheral vestibular end organs and balance function should be evaluated to comprehensively understand ISSNHL. Better assessment of the condition will help us in clinical diagnosis, treatment and prognosis evaluation of ISSNHL.

The significance of directional preponderance in the evaluation of vestibular function in patients with vertigo

Objective: To analyze the relationship between directional preponderance (DP), spontaneous nystagmus(SN) and vestibular disorders, and to investigate the significance of DP in directing peripheral vestibular function in patients with vertigo. Methods: This was a retrospective analysis of 394 cases diagnosed with peripheral vestibular disease accompanied by vertigo from March 2012 to June 2014 in the Outpatient Department of the Eye & ENT Hospital of Fudan University. Results of static and dynamic posture equilibrium tests, SN, unilateral weakness(UW), and DP in videonystagmography(VNG) were analyzed and compared. Results: The mean interval time between the last vertigo attack and examination in patients with SN or DP in caloric test were 4.4 d and 7.3 d respectively, and those without SN or DP were 18.3 d and 17.5 d respectively. The patients were divided into two groups according to DP results of caloric test. DP-normal group had 203 cases and DP-abnormal group had 191 cases. Spontaneous nystagmus was presented in 44 cases in the DP-normal group (21.67%) and four in the DP-abnormal group (2.09%). A significant difference was found between the two groups (χ2=35.27, P=0.000). Deficiency of vestibular function was noted in 165 cases in the DP-normal group (81.28%) and 123 (64.40%) in the DP-abnormal group in static and dynamic posture equilibrium tests. The difference between the two groups was statistically significant (χ2=14.26, P=0.000). Conclusion: Compared with DP-normal patients, DP-abnormal patients are more likely to have spontaneous nystagmus and balance disorders due to vestibular dysfunction.

Deterioration of Vestibular Cells in Labyrinthitis.

To quantitatively assess the effect of serous labyrinthitis, suppurative labyrinthitis, and labyrinthitis ossificans on vestibular hair cells, dark cells, and transitional cells. We examined human temporal bone specimens with serous labyrinthitis, suppurative labyrinthitis, and labyrinthitis ossificans, then compared them with age-matched control groups without labyrinthitis. We evaluated the density of type I and II vestibular hair cells, dark cells, and transitional cells in the peripheral sensorial organs. The mean density of type I vestibular hair cells in the maculae of the saccule significantly differed between the serous labyrinthitis group and its control group. The loss of type I and II vestibular hair cells in all of the peripheral sensorial organs was significantly higher in the suppurative labyrinthitis group than in its control group. The mean density of dark cells in the lateral and posterior semicircular canals was significantly lower in the suppurative labyrinthitis group than in its control group. The mean density of type I and II vestibular hair cells, dark cells, and transitional cells was significantly lower in the labyrinthitis ossificans group than in its control group. The loss of vestibular hair cells and degenerative changes in dark cells and transitional cells could affect vestibular function in patients with labyrinthitis.

Vestibular function in patients with Niemann-Pick type C disease.

We investigated whether vestibular dysfunction may cause or contribute to postural imbalance and falls in patients with Niemann-Pick type C disease (NP-C). Eight patients with NP-C disease and 20 healthy controls were examined using the video-based head impulse test (vHIT) and caloric irrigation to investigate horizontal canal function as well as ocular- and cervical vestibular evoked myogenic potentials (o- and cVEMP), and binocular subjective visual vertical estimation (SVV) for otolith function, and static posturography. There were no significant differences in vestibulo-ocular gain, caloric excitability, o-/cVEMP measures or SVV between the two groups. Posturographic total sway path (tSP) and root mean square (RMS) were significantly higher in NP-C than in controls in 3 out of 4 conditions. The Romberg quotient (RQ) to assess the amount of visual stabilization was significantly lower in the NP-C than in the HC group. In contrast to other inherited metabolic disorders, such as Morbus Gaucher type 3, we did not find any evidence for an impairment of canal or otolith function in patients with NP-C as their cause of postural imbalance. Since RQ was low in NP-C patients, indicating proper sensory input, the observed increased postural sway is most likely due to a cerebellar dysfunction in NP-C, which may therefore, explain postural imbalance.

Vestibular Impairment in Frontotemporal Dementia Syndrome

Background: No studies to date have attempted to evaluate frontotemporal lobar degeneration from the perspective of the vestibular system. Objective: The present study examined vestibular function in patients with frontotemporal dementia (FTD) clinical syndrome and evaluated whether vestibular disorders are involved in the clinical symptoms due to FTD. Methods: Fourteen patients with FTD syndrome, as well as healthy elderly controls without dementia, were included in the present study. All subjects underwent vestibular function tests using electronystagmography, such as caloric tests and visual suppression (VS) tests, in which the induced caloric nystagmus was suppressed by visual stimuli. The association between clinical symptoms and vestibular function in the FTD syndrome group was further examined. Results: In the FTD syndrome group, caloric nystagmus was not necessarily suppressed during VS tests. Furthermore, VS was observed to be significantly impaired in FTD syndrome patients with gait disturbance as compared to those without such disturbance. Conclusion: The present study revealed that impairment of VS in patients with FTD results in an inability to regulate vestibular function by means of visual perception, regardless of multiple presumed neuropathological backgrounds. This could also be associated with gait disturbance in patients with FTD syndrome.

Influence of cochlear implantation on vestibular function

Conclusion Vestibular function in patients can be damaged following cochlear implantation. Therefore, assessing the pre-operative vestibular status, carefully choosing the side of implantation, and preserving function by using minimally invasive surgical techniques are important. Objectives The aim of this study was to assess the influence of cochlear implantation on vestibular function in patients with severe and profound sensorineural hearing loss, and to analyze a possible correlation between the changes in vestibular testing and post-operative vestibular symptoms. Methods Thirty-four patients were evaluated for vestibular function using the cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP, respectively), and 29 patients underwent caloric tests pre-operatively and 4 weeks post-operatively. Results Before surgery, the cVEMPs were recorded bilaterally in 22 patients, unilaterally in eight patients, and absent bilaterally in four patients. The oVEMPs were recorded bilaterally in 19 patients, unilaterally in six patients, and absent bilaterally in nine patients. After implantation, the cVEMPs were absent in 10 patients and the oVEMPs were absent in seven patients on the implanted side. Caloric tests demonstrated canal paresis in 17 patients, and normal responses were recorded in 12 of the 29 patients pre-operatively. There was a significant decrease post-implantation in the ear implanted, with the exception of two patients. Two patients presented with vertigo and another two patients reported slight unsteadiness post-operatively, but all symptoms resolved within 7 days. The impaired vestibular function did not correlate with vestibular symptoms, age, or gender. Function on the contralateral side remained unaffected.

Influence of Diazepam on Video Head Impulse Test in Patients with Acute Vestibular Neuritis: Preliminary Study

Received June 9, 2015 Revised August 28, 2015 Accepted August 30, 2015 Address for correspondence Minbum Kim, MD Department of OtorhinologyHead and Neck Surgery, Catholic Kwandong University College of Medicine, 25 Simgok-ro 100beon-gil, Seo-gu, Incheon 22711, Korea Tel +82-32-290-3978 Fax +82-32-290-3050 E-mail minbumkim78@gmail.com Background and ObjectivesZZAlthough video head impulse test (V-HIT) has emerged as a popular test for vestibular function, there have been no reports about the influence of benzodiazepine on the test. The aim of this study is to investigate the influence of diazepam on the V-HIT in patients with acute vestibular neuritis. Subjects and MethodZZWe retrospectively analyzed charts and medical records of 10 patients diagnosed with acute vestibular neuritis. The patients repeated V-HIT before and after intravenous (IV) injection of diazepam. Gain and presence of catch-up saccade (CUS) were compared. ResultsZZGain in the affected ear was decreased compared to that in the unaffected ear. After the injection of IV diazepam, the presence of CUS was not changed significantly. Gain of CUS in V-HIT was also unchanged both in the affected and unaffected ear after the injection of IV diazepam. ConclusionZZThe influence of IV diazepam on the gain and presence of CUS in V-HIT were insignificant, indicating that it could be considered as a useful test to evaluate vestibular function in patients treated with diazepam. Korean J Otorhinolaryngol-Head Neck Surg 2016;59(1):15-8

Vestibular Implants: 8 Years of Experience with Electrical Stimulation of the Vestibular Nerve in 11 Patients with Bilateral Vestibular Loss

Background: The concept of the vestibular implant is primarily to artificially restore the vestibular function in patients with a bilateral vestibular loss (BVL) by providing the central nervous system with motion information using electrical stimulation of the vestibular nerve. Our group initiated human trials about 10 years ago. Methods: Between 2007 and 2013, 11 patients with a BVL received a vestibular implant prototype providing electrodes to stimulate the ampullary branches of the vestibular nerve. Eye movements were recorded and analyzed to assess the effects of the electrical stimulation. Perception induced by electrical stimulation was documented. Results: Smooth, controlled eye movements were obtained in all patients showing that electrical stimulation successfully activated the vestibulo-ocular pathway. However, both the electrical dynamic range and the amplitude of the eye movements were variable from patient to patient. The axis of the response was consistent with the stimulated nerve branch in 17 out of the 24 tested electrodes. Furthermore, in at least 1 case, the elicited eye movements showed characteristics similar to those of compensatory eye movements observed during natural activities such as walking. Finally, diverse percepts were reported upon electrical stimulation (i.e., rotatory sensations, sound, tickling or pressure) with intensity increasing as the stimulation current increased. Conclusions: These results demonstrate that electrical stimulation is a safe and effective means to activate the vestibular system, even in a heterogeneous patient population with very different etiologies and disease durations. Successful tuning of this information could turn this vestibular implant prototype into a successful artificial balance organ.

The effect of intra-tympanic dexamethasone on the vestibular function in patients with recurrent vertigo

Conclusion: The low clinical efficacy of the treatment for patients included in this work correlates with no noticeable effect on the vestibular function. Objective: To assess follow-up in patients with idiopathic and secondary Ménière’s disease after treatment with intra-tympanic dexamethasone and correlate clinical findings with changes in the vestibular-ocular reflex elicited after stimulation of each of the six semicircular canals. Methods: This is a single center retrospective review of patients presenting the clinical symptomatology of Meniérè’s disease treated with intra-tympanic dexamethasone. An audiometric evaluation was performed in each patient before and after treatment. The study cohort was divided into two groups: those evaluated after a short period of time and after a long period of time. Results: The study included 30 patients, mean age = 61 years. Differences in mean pure-tone average before and after treatment were non-significant for both treated (0.61 dB, p = 0.723) and untreated (0.59 dB, p = 0.609) ears. Vestibular–ocular reflex gain averages in the treated ear after treatment were 0.73 (superior semicircular canal), 0.86 (horizontal semicircular canal), and 0.69 (posterior semicircular canal). The gain did not vary significantly in the Superior (p = 0.194), the Horizontal (p = 0.646), or the Posterior Semicircular Canal (p = 0.820). Similar were obtained for the untreated ear.

Condition of vestibular function in patients with Meniere's disease for the early term after treatment

The efficiency rating of the treatment in patients with Meniere's disease was performed with the help of different methods in accordance to vestibular function for the early term (in 3 months) after treatment. Improvement of clinical course was observed in all groups of patients. However. complex therapy became the most effective method which included pneumomassage of labyrinthine windows and kinesitherapy. The article shows advantages of complex therapy over the medication therapy according to assessment of vestibular dysfunction.

Evaluation of Vestibular Function in Patients with Chronic Suppurative Otitis Media

Objective: The objective of this study was to assess vestibular functions in patients with chronic suppurative otitis media (CSOM) with and without sensorineural hearing loss. Study Design: This was a prospective case study performed at a tertiary referral university hospital. Sixty patients with CSOM were included, and patients with a history of head trauma, diabetes, hypertension, previous ear surgery, use of ototoxic drugs, neurological deficits and suspected fistulae were excluded. Patients and Methods: The patients underwent basic audiological evaluation, and clinical and instrumental vestibular evaluation. The incidence and extent of vestibular dysfunction in patients with CSOM were analyzed. Results: A total of 42 males and 16 females with a mean age of 29.5 years were included in this study. Forty ears had tubotympanic disease and 19 had cholesteatoma. There were 14 ears with sensorineural hearing loss. A positive history of vertigo was reported in 53.5% of the cases. Rotatory chair abnormalities were found in 70% of the cases, caloric hypofunction was found in 61.6%, and vestibular myogenic evoked potentials were abnormal in 25%. The only positive correlation with vestibular dysfunction was the duration of disease. Conclusions: The vestibular system is significantly affected in cases with CSOM. Both semicircular canals and the saccule are affected. All patients with long-standing CSOM should be evaluated for vestibular dysfunction irrespective of their hearing levels.

Effect of strabismus on vestibular functions: value of its correction

Objective Studies that evaluate the relationship between strabismus and vestibular functions are very scarce with no consensus between their results. Hence, this study was designed to evaluate vestibular functions in patients with strabismus and to find out the effect of surgical correction of strabismus on vestibular functions. Materials and methods Thirty patients with strabismus aged between 10 and 33 years constituted the study group. The following procedures were carried out: otological examinations, detailed vertigo history, neurological and ophthalmological examinations, basic audiological evaluation, office tests for vestibular evaluation, videonystagmography, and computerized dynamic posturography. These vestibular tests either office tests or laboratory tests were performed three times, before eye surgery and 1 month and 2 months after eye surgery. Results Before surgery, in office tests for vestibular function, 36.6% of patients had abnormal results in dynamic visual acuity, whereas 26.7 and 16.7% had abnormalities in head thrust and head shake tests. In addition, 43.3% had abnormal sharpened Fukuda stepping test, whereas 33.3 and 13.3% had abnormal CTSIB and Fukuda stepping test. Reduction in equilibrium scores as well as condition 3, 5, and 6 of sensory organization test in all patients showed abnormal videonystagmography test results. Improvement occured postoperatively in office as well as laboratory tests. Conclusion Vestibular functions in strabismus patients are globally better in postoperative than in preoperative conditions, and this improvement appeared to be stable.

Influence on Vestibular Function by Auditory Neuropathy

ObjectiveThe main purpose of the present study was to describe the vestibular function in patients with auditory neuropathy (AN), and to assess their ability to maintain balance. MethodsVestibular function tests were performed on 32 patients with AN and 36 normal subjects including electronystagmopraphy(ENG) and static postrography(SPG). The results from the two groups were compared. ResultsEquilibrium function in patients with AN, was abnormal, compared to normal subjects. ConclusionVestibular function tests, especially static postrography, should be performed on patients with AN.

Effects of EAS cochlear implantation surgery on vestibular function

Conclusions: The patients who received electric acoustic stimulation (EAS) cochlear implantation had relatively good vestibular function compared with the patients who did not have residual hearing. The vestibular function was well preserved after atraumatic EAS surgery. The round window approach and soft electrode are preferred to decrease the risk of impairing vestibular function. Objectives: The aim of this study was to examine the characteristic features of vestibular functions before and after implantations in patients undergoing EAS. Methods: Vestibular functions in patients who underwent EAS implantation were examined by caloric testing and vestibular evoked myogenic potential (VEMP) in 11 patients before and in 13 patients after implantation. Results: Preoperative evaluation showed that of the 11 patients, most (73%) had good vestibular function. One of 11 patients (9%) had decreased response in postoperative VEMP but all of the patients had unchanged results in postoperative caloric testing.

Evaluation of the vestibulo-ocular reflex using sinusoidal off-vertical axis rotation in patients with canal paresis

The vestibulo-ocular reflex (VOR) was studied to determine the utility of off-vertical axis rotation (OVAR) in evaluating vestibular function in patients with canal paresis (CP). Our goal was to determine whether there is any correlation between caloric responses and sinusoidal rotatory responses. Subjects were rotated in a sinusoidal pattern with eyes open in complete darkness. Frequencies of 0.4 and 0.8Hz with a maximum angular velocity of 60°/s at either earth-vertical axis rotation (EVAR) or OVAR were used. Twenty-three control subjects and 21 patients with CP were investigated. Results showed that (1) the VOR gain difference between EVAR and OVAR in the CP patients was not significant at 0.4Hz and at 0.8Hz; (2) the gain during 0.4Hz EVAR was less in the bilateral CP patients compared to controls; and (3) the VOR gain of the affected side at 0.8Hz was significantly less during OVAR than during EVAR. We concluded that the absence or reduction of caloric responses does not indicate the absence of vestibular function. In addition, separation analysis of the VOR gain of affected and intact sides is useful for evaluating laterality of otolith function in patients with CP.

Cochlear Implantation Rarely Alters Horizontal Vestibulo-ocular Reflex in Motorized Head Impulse Test

Determine the change in vestibular function in patients receiving a unilateral cochlear implant, and to compare these results with other signs and symptoms. Prospective cohort study. Academic tertiary referral center. Forty-four adults (mean age, 55 yr; range, 30-76 yr) receiving their first cochlear implant. Cochlear implantation. Horizontal high-frequency vestibulo-ocular reflex (VOR) was measured using the motorized head impulse rotator preoperatively and twice (on average two and 19 months) postoperatively. VOR gain and asymmetry were calculated (mean ± standard deviation). Symptoms were assessed with a structured questionnaire. Gain on the operated side was 0.77 ± 0.26 preoperatively, 0.75 ± 0.30 in the early and 0.73 ± 0.33 in the late postoperative control, and did not change significantly. Mean asymmetry remained within 9% to 10% in all test occasions. Dizziness symptom score or dizziness-related quality of life score did not change significantly. General quality-of-life score improved significantly from that of preoperative 3.5 ± 1.2 to that of 2.6 ± 1.1 postoperatively (p = 0.01). Subjective hearing scores improved significantly from 4.9 ± 0.3 to 2.4 ± 1.0, respectively (p = 0.0000). Gain was decreased significantly in 4 patients (10%) in the early and in 2 patients (7%) in the late postoperative control. Late high-frequency loss of vestibular function or vestibular symptoms is rare but possible after cochlear implantation surgery. This should be taken into account in patient counseling especially when considering bilateral cochlear implant surgery.