Objective:This study aimed to analyze the results of auditory and vestibular function tests in patients with unilateral vestibular schwannoma and explore their association with tumor size. Methods:Clinical data from 81 patients diagnosed with unilateral vestibular schwannoma who underwent pure-tone audiometry（PTA）, cervical and ocular vestibular evoked myogenic potentials（c/oVEMP）, as well as video head impulse test（vHIT）, and subsequently underwent surgical treatment, were retrospectively analyzed. Patients were categorized into groups based on tumor size: small （≤ 15 mm）, medium（16-30 mm）, and large （>30 mm）, determined by the maximum tumor diameter on contrast-enhanced MRI scans. Results:PTA results indicated hearing loss in 73 cases（90.1%）; vestibular function tests revealed abnormal rates for the anterior semicircular canal, horizontal semicircular canal, posterior semicircular canal, utricle, and saccule at 29.6%, 77.8%, 54.3%, 90.1%, and 92.6%, respectively. Statistically, no significant differences were found in preoperative hearing test results among patients in different groups（F=0.393, P=0.676）. However, significant differences were observed in horizontal semicircular canal gain（r=-0.248, P=0.025）, abnormal rates of horizontal semicircular canal catch-up saccades（r=0.507, P<0.001）, as well as cVEMP（χ²=15.111, P=0.004） and oVEMP thresholds（χ²=18.948, P<0.001） across varying tumor size groups. Conclusion:The extent of hearing loss in patients with vestibular schwannoma is not correlated with tumor size, whereas the degree of vestibular dysfunction demonstrates a correlation with tumor size.
Humans ; Neuroma, Acoustic/physiopathology* ; Retrospective Studies ; Audiometry, Pure-Tone ; Vestibular Function Tests ; Vestibular Evoked Myogenic Potentials ; Female ; Male ; Head Impulse Test ; Middle Aged ; Adult ; Semicircular Canals/physiopathology* ; Aged ; Hearing Loss/physiopathology*

BACKGROUNDDetermining the nerve of origin for vestibular schwannoma (VS), as a method for predicting hearing prognosis, has not been systematically considered. The vestibular test can be used to investigate the function of the superior vestibular nerve (SVN) and the inferior vestibular nerve (IVN). This study aimed to preoperatively distinguish the nerve of origin for VS patients using the vestibular test, and determine if this correlated with hearing preservation.

METHODSA total of 106 patients with unilateral VS were enrolled in this study prospectively. Each patient received a caloric test, vestibular-evoked myogenic potential (VEMP) test, and cochlear nerve function test (hearing) before the operation and 1 week, 3, and 6 months, postoperatively. All patients underwent surgical removal of the VS using the suboccipital approach. During the operation, the nerve of tumor origin (SVN or IVN) was identified by the surgeon. Tumor size was measured by preoperative magnetic resonance imaging.

RESULTSThe nerve of tumor origin could not be unequivocally identified in 38 patients (38/106, 35.80%). These patients were not subsequently evaluated. In 26 patients (nine females, seventeen males), tumors arose from the SVN and in 42 patients (18 females, 24 males), tumors arose from the IVN. Comparing with the nerve of origins (SVN and IVN) of tumors, the results of the caloric tests and VEMP tests were significantly different in tumors originating from the SVN and the IVN in our study. Hearing was preserved in 16 of 26 patients (61.54%) with SVN-originating tumors, whereas hearing was preserved in only seven of 42 patients (16.67%) with IVN-originating tumors.

CONCLUSIONSOur data suggest that caloric and VEMP tests might help to identify whether VS tumors originate from the SVN or IVN. These tests could also be used to evaluate the residual function of the nerves after surgery. Using this information, we might better predict the preservation of hearing for patients.

Adult ; Female ; Hearing ; Humans ; Male ; Neuroma, Acoustic ; pathology ; physiopathology ; Vestibular Nerve ; physiology

OBJECTIVE: To observe the ocular vestibular evoked myogenic potential (oVEMP) and the cervical vestibular evoked myogenic potential (cVEMP) in patients with vestibular diseases. METHOD: From March, 2011 to March, 2012, 13 patients (14 ears) with peripheral vestibular diseases were recruited. Each patient underwent conventional oVEMP and cVEMP examinations elicited by intensive air conducted sound (short tone burst, 500 Hz) in bilateral ears. RESULT: Thirteen cases (14 ears) were included in this study. They were 3 cases (3 ears) with Ramsay Hunt syndrome, 3 cases (4 ears) with acoustic neuroma, 1 case (1 ear) with VII and VIII cranial nerve trauma after head injury, 2 cases (2 ears) with vestibular neuritis, 3 cases (3 ears) with Meniere's disease, and Icase (1 ear) with unilateral hypoplasia of the internal auditory canal. Altogether, oVEMP could be elicited in only 2 ears (14. 3%) and cVEMP were found abnormal in 11 ears (78. 6%). CONCLUSION The otolithic vestibular end organs and their input pathways could be examined by cVEMP and oVEMP examinations in patients with peripheral vestibular disorders.
Acoustic Stimulation ; Eye ; Humans ; Meniere Disease ; Neuroma, Acoustic ; Otolithic Membrane ; Vestibular Diseases ; physiopathology ; Vestibular Evoked Myogenic Potentials ; Vestibular Neuronitis ; Vestibule, Labyrinth

BACKGROUNDSmall acoustic neuromas seldom result in typical vestibular symptoms, despite the tumor arising from the vestibular nerve. In this study, we have shown that abnormal gait in eleven patients with small acoustic neuroma could be detected in gait analysis by the use of tactile sensor. Patients displayed no oculomotor abnormality and had tumors less than 10 mm from the porus acoustics.

METHODSGait related parameters including the coefficients of variations (CV) of stance, swing, double support, area ratio of trajectories of center of force (TCOF), in addition to the foot pressure difference between both feet, were used for assessment of gait.

RESULTSThe CV of swing and the area ratio of TCOF were greater in patients than those in the control group (P < 0.05). The values of these two parameters became greater under an eyes closed condition compared to eyes open (P < 0.05) in the patient group.

CONCLUSIONThese results indicate that gait analysis may be helpful to assess vestibulospinal function of patients with small acoustic neuroma, the slight vestibular deficits of which can not be detected by visual observation.

Adult ; Aged ; Female ; Gait Disorders, Neurologic ; diagnosis ; etiology ; Humans ; Male ; Middle Aged ; Neuroma, Acoustic ; physiopathology

OBJECTIVESTo evaluate the long-term facial nerve function of patients following microsurgical removal of large and huge acoustic neuroma, and to identify the factors that influence these outcomes.

METHODSA retrospective review was performed which included 176 consecutive patients with a large acoustic neuroma (≥ 30 mm) underwent a retrosigmoid craniotomy for tumor resection between January 2002 to November 2009. House-Brackmann (HB) Scale was used preoperatively and in a long-term follow-up after surgery. Test for linear trend was applied for statistic analysis.

RESULTSComplete resection was achieved in 168 (95.5%) of these 176 patients with a mortality of 1.7%. Anatomic preservation of the facial nerve was attained in 96.0% of the patients. In the series of 96 patients who had at least 1-year follow-up (mean 3.0 years) the facial nerve function preservation (HB grade 1 - 2) was totally attained in 79 patients (82.3%), and 40 of 55 patients (72.7%) who presented huge tumors (diameter > 40 mm) among the 96 patients had facial nerve function preserved. Analysis showed that facial nerve function correlated linearly with tumor sizes (χ(2) = 14.114, ν = 1, P < 0.05).

CONCLUSIONSComplete removal of large and giant acoustic neuroma may be obtained via retrosigmoid approach with facial nerve preservation. Excellent long-term facial function can be expected in the majority of patients who undergo microsurgical removal of vestibular schwannoma via the suboccipital retrosigmoid approach. Tumor size is a significant prognostic parameter for facial nerve function following vestibular schwannoma surgery.

Adolescent ; Adult ; Aged ; Facial Nerve ; physiopathology ; surgery ; Female ; Follow-Up Studies ; Humans ; Male ; Microsurgery ; Middle Aged ; Neuroma, Acoustic ; surgery ; Prognosis ; Retrospective Studies ; Treatment Outcome ; Young Adult

OBJECTIVE: To establish the normal value of the vestibular evoked myogenic potential (VEMP), and to determine the characteristics of VEMP in patients with acoustic neuroma (AN) and to explore the significance of VEMP in diagnosis of AN. METHOD: Click-evoked VEMP was recorded with surface electrodes attached on the sternocleidomastoid muscle. Latencies and amplitudes of specific waveform of VEMP were measured. The hearing normal subjects including 26 males and 20 females were chosen to establish the normal value of VEMP. VEMP was investigated in 14 patients with AN who underwent surgery during the period of 2006-2007 as well as auditory brainstem response (ABR) and vestibular caloric test. RESULT: Of 46 subjects with normal hearing, VEMP was present in both ears in 43 subjects, absent in either ear in three subjects. The reducible rate is 93.5% (86/92). The nor-mal value obtained from 86 reducible ears were as follows (means +/- standard deviation): latency of p13 (11.86 +/- 2.11) ms, latency of n23 (18.57 +/- 2.19) ms, interval time between p13 and n23 (6.71 +/- 1.69) ms, amplitude of p13n23 (24.18 +/- 8.22) microV. Interaural variances in 43 subjects whose VEMP were available were as follows (means +/- standard deviation): /deltap13 (0.64 +/- 0.61) ms, /deltan23/(1.05 +/- 0.97) ms, interval time between /delta13n23/ (0.84 +/- 0.81) ms, amplitude ratio (max/min) 1.32 +/- 0. 37, interaural asymmetric ratio of VEMP 0.12 +/- 0.11. Of the 14 patients with AN, VEMP was absent on the affected side in eight patients, absent on either side in three patients, and present on the unaffected side in 11 patients. VEMP presented on the affected side in three patients was significantly prolonged in /deltapl3/ and /deltap13n23/. CONCLUSION Patients with AN characterized with VEMP could be useful in the diagnosis of AN combined together with other tests.
Acoustic Stimulation ; Adult ; Case-Control Studies ; Electromyography ; Evoked Potentials, Auditory ; Female ; Humans ; Male ; Middle Aged ; Neuroma, Acoustic ; physiopathology ; Vestibular Function Tests ; Young Adult

BACKGROUNDAlthough various monitoring techniques have been used routinely in the treatment of the lesions in the skull base, iatrogenic facial paresis or paralysis remains a significant clinical problem. The aim of this study was to investigate the effect of intraoperative facial motor evoked potentials monitoring with transcranial electrical stimulation on preservation of facial nerve function.

METHODFrom January to November 2005, 19 patients with large acoustic neuroma were treated using intraoperative facial motor evoked potentials monitoring with transcranial electrical stimulation (TCEMEP) for preservation of facial nerve function. The relationship between the decrease of MEP amplitude after tumor removal and the postoperative function of the facial nerve was analyzed.

RESULTSMEP amplitude decreased more than 75% in 11 patients, of which 6 presented significant facial paralysis (H-B grade 3), and 5 had mild facial paralysis (H-B grade 2). In the other 8 patients, whose MEP amplitude decreased less than 75%, 1 experienced significant facial paralysis, 5 had mild facial paralysis, and 2 were normal.

CONCLUSIONSIntraoperative TCEMEP can be used to predict postoperative function of the facial nerve. The decreased MEP amplitude above 75 % is an alarm point for possible severe facial paralysis.

Adult ; Aged ; Electric Stimulation Therapy ; Electromyography ; Evoked Potentials, Motor ; Facial Nerve ; physiopathology ; Female ; Humans ; Male ; Middle Aged ; Monitoring, Intraoperative ; Neuroma, Acoustic ; physiopathology

OBJECTIVETo investigate the value of intraoperative auditory monitoring techniques in acoustic neuroma surgery.

METHODSTen cases with acoustic neuroma were resected with retrosigmoid approach. Continuous hearing monitoring of auditory brainstem responses (ABR) and transtympanic electrocochleography (ECochG) was performed during operation.

RESULTSBefore surgery, 3 patients had class A hearing, 4 had class B hearing, and 3 had class C hearing. With ABR monitoring, 5 patients had waves I , III and V, 5 had only waves I preoperation. After anesthesia,only 2 cases had waves I, III and V, 6 had wave I (Compound action potential, CAP N1 is equivalent to wave I of ABR) and 2 had no waves. The hearing was preserved in 2 cases, which had class A hearing post operation with tumor size <2 cm. With continuous hearing monitoring, the waves of I , III and V could be evoked in one case. In another case, the waves of I, III could be evoked after the tumor resection with the disappearance of wave V. The hearing was not preserved in 8 cases. The 6 out of 8 cases showed up CAP (waves I ) waveform. The CAP amplitudes decreased significantly in 4 cases and even dropped to zero while dissecting the tumor at the lateral end of the internal auditory canal (IAC) or clamping the internal auditory artery (IAA) during operation. After surgery, the CAP amplitudes were recovered to 50%-60% of normal level or normal. In one case, although the cochlear nerve was cut down, the CAP could still be recorded after the tumor resection. However, the CAP amplitudes was dropped to zero while pressurized and pulled cochlea nerve of brainstem lateral and the wave disappeared post-operation in another cases. The waves had not been recorded in two cases after anesthesia. One of them showed low amplitude of CAP wave when the tumor partially removed. The others had no wave all the time.

CONCLUSIONSIn combination with ABR monitoring, ECochG proved to be a useful supplementary tool for hearing preservation in acoustic neurinoma surgery. Drilling of the IAC and tumor removal at the lateral end of the IAC were the most critical steps for achieving hearing preservation. The surgeon's experience are the most significant factors influencing the hearing outcome after removal of acoustic neuroma.

Adolescent ; Adult ; Audiometry, Evoked Response ; Cochlear Nerve ; physiopathology ; Evoked Potentials, Auditory, Brain Stem ; Female ; Humans ; Male ; Middle Aged ; Monitoring, Intraoperative ; methods ; Neuroma, Acoustic ; physiopathology ; surgery ; Young Adult