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Biomedical subjects

D B Welling

Publications and source records attributed to D B Welling.

At least 19 recordsLinked to original sources

Long-term stapedectomy results with the McGee stapes prosthesis.

OBJECTIVE: To report long-term follow up on patients undergoing stapedectomy with the McGee stapes prosthesis. STUDY DESIGN: A retrospective case series. METHODS: Charts recording 170 stapedectomies (120 primary and 50 revision stapedectomies) from 1989 to 1999 were analyzed, and audiometric data and the findings at repeat exploration reported. RESULTS: Over a 10-year period, 11.2% of patients had failure of their initial air-bone gap closure with the McGee piston. Seventy-seven percent (in 10 of 13 patients) of McGee pistons that failed were found to have the platinum ribbon displaced laterally from the incus and the piston pushed out of the stapedotomy. The failure rate was not significantly different (P =.72) from that in our patients who underwent placement of a Robinson cup prosthesis (9.5%), but the pattern of displacement was unique. Failures occurred earlier with the McGee piston (average time to failure of 2.5 y) than with the Robinson cup (average time to failure of 8.6 y). CONCLUSION: The McGee piston was found to have a unique pattern of dislocation that is likely related to the malleable nature of the platinum ribbon and loosening of the crimped "shepherd's crook" over time.

Follow-Up Studies↗

Expression of cytokine and chemokine genes by human middle ear epithelial cells induced by formalin-killed Haemophilus influenzae or its lipooligosaccharide htrB and rfaD mutants.

To define the role of nontypeable Haemophilus influenzae (NTHI) lipooligosaccharide (LOS) in the induction of proinflammatory cytokine gene expression during otitis media, we compared the abilities of formalin-killed NTHI strain 2019 and its LOS htrB and rfaD mutants to stimulate human middle ear epithelial (HMEE) cell cytokine and chemokine gene expression and production in vitro. Strain DK-1, an rfaD gene mutant, expresses a truncated LOS consisting of only three deoxy-D-manno-octulosonic acid residues, a single heptose, and lipid A. Strain B29, an isogenic htrB mutant, possesses an altered oligosaccharide core and an altered lipid A. HMEE cells were incubated with formalin-killed NTHI 2019, B29, or DK-1. The supernatants and the cells were collected at 2, 4, 8, and 24 h after stimulation. Expression of genes for the cytokines tumor necrosis factor alpha (TNF-alpha), interleukin lbeta (IL-1beta), and IL-6 and for the chemokines macrophage inflammatory protein 1beta (MIP-1beta), monocyte chemotactic peptide 1 (MCP-1), and IL-8 was quantitated by real-time PCR. NTHI B29 did not significantly stimulate any cytokine or chemokine mRNA expression in HMEE cells. In striking contrast, NTHI 2019 induced up to 105-, 139-, and 187-fold increases in HMEE cell expression of IL-1beta, TNF-alpha, and MIP-1beta, respectively (P < 0.01 [2019 versus B29]). NTHI 2019 also induced upregulation of IL-8, IL-6, and MCP-1 mRNA expression (by 26-, 44-, and 14-fold, respectively [P < 0.05 (2019 versus B29)]). The significant induction of cytokine genes was confirmed by quantitating the secretion of cytokines in culture supernatants with an enzyme-linked immunosorbent assay. There were no significant differences in mRNA expression of IL-8, IL-6, and MCP-1 between the 2019- and DK-1-treated groups. The low levels of gene transcripts observed after incubation of HMEE cells with B29 indicate that products of the disrupted NTHI htrB LOS gene may play a major role in induction of these particular inflammatory mediators.

Adult↗

Endolymphatic mastoid shunt: a reevaluation of efficacy.

OBJECTIVES: The main goal of this paper was to statistically reevaluate the efficacy of the endolymphatic shunt procedure for Meniere's disease. METHODS: Thomsen et al (Arch Otolaryngol 1981;107:271-7) reported on the placebo effect in surgery for Meniere's disease in a controlled double-blind study. Thirty patients with typical Meniere's disease in whom medical treatment failed participated in the study. A placebo-controlled blinded surgical study has not since been replicated. We performed a retrospective statistical analysis using data extracted from the published report and reanalyzed it using both the original and new statistical measures and techniques. RESULTS: The original conclusions drawn by Thomsen et al differed considerably from ours in 5 key areas, including postoperative vertigo, nausea and vomiting, tinnitus, and combined score. CONCLUSIONS: This analysis strongly supports the effectiveness of the endolymphatic shunt in the management of Meniere's disease and refutes the placebo effect previously proposed.

Double-Blind Method↗

Analysis of the human neurofibromatosis type 2 gene promoter and its expression.

OBJECTIVE: It is hypothesized that transcriptional regulation plays an important role for neurofibromatosis type 2 (NF2) expression in Schwann cells and other cell types. The objective of this study is the isolation and characterization of the transcriptional regulatory elements of the NF2 gene. STUDY DESIGN AND SETTING: A bacterial artificial chromosome library and a partial genomic DNA library were used to isolate the human NF2 gene; NF2 promoter-luciferase constructs were generated, and promoter activities were assayed. This study was carried out in a molecular biology laboratory. RESULTS: A bacterial artificial chromosome clone with an approximately 100-kilobase insert containing nearly the entire human NF2 gene has been isolated. An additional 5' NF2 sequence has also been cloned. Transient transfection experiments demonstrate strong promoter activity from the NF2 5' flanking DNA. CONCLUSIONS: The NF2 gene is approximately 100 kilobases long. Both positive and negative regulatory elements are present in NF2 5' flanking regions. SIGNIFICANCE: Better understanding of the NF2 gene and its regulation will improve molecular diagnostics and ultimately treatment of patients with NF2.

Base Sequence↗

Tumor growth and audiometric change in vestibular schwannomas managed conservatively.

OBJECTIVE: To prospectively define the correlation between changes in tumor volume and audiometric function in vestibular schwannomas managed conservatively. STUDY DESIGN: Prospective longitudinal study. METHODS: Twenty-one patients (age range, 15-84 y; mean age, 63.3 y) with newly diagnosed vestibular schwannomas were enrolled between 1994 and 1999 in a protocol at The Ohio State University Hospital (Columbus, OH) to evaluate the correlation between tumor volume and audiometric change during a period of observation. Patients were evaluated yearly by clinical examination, a standardized internal auditory canal magnetic resonance imaging scan with gadolinium contrast for volumetric analysis, and audiometric function testing. Demographic data, historical features, neurofibromatosis type 2 (NF2) status, initial testing results, and serial testing results were recorded. RESULTS: An increase in tumor volume occurred in 14 of the 21 patients (66%). The pattern of volumetric change was found to be extremely variable. Multiple regression analysis revealed significant correlations of changes in tumor volume with changes in pure-tone average and speech discrimination score (P < .0001 and P = .0021, respectively). Change in tumor volume had greater effect on pure-tone average and speech discrimination score in patients initially with class D audiometric function when compared with those initially in class A (P = .0083 and P = .0245, respectively). The presence of NF2 had an independent protective effect against deterioration of the pure-tone average when compared with patients without NF2 (P = .0125). CONCLUSIONS: This study demonstrated a significant correlation between a change in volume and auditory deterioration in vestibular schwannomas being managed with a trial of observation. A given change in tumor volume appeared to have a greater effect on pure-tone average and speech discrimination score as initial auditory classification declined.

Adolescent↗

Preoperative antibiotics and steroids in vestibular schwannoma excision.

OBJECTIVE: To examine the benefits of preoperative admission for intravenous steroids and antibiotics for patients undergoing vestibular schwannoma excision. STUDY DESIGN: Retrospective cohort study. METHODS: One hundred twenty patients with pathologically confirmed vestibular schwannoma followed for at least 1 year after surgery were included. Sixty patients were assigned to the preoperative admission group and 60 patients to the same-day-admission surgery group. The preoperative admission group was given intravenous dexamethasone (0.1 mg/kg) and intravenous cefazolin (1 g) beginning 12 hours before surgery. The same-day-surgery group received the same dosage of medication beginning at induction of anesthesia. OUTCOMES: Facial nerve function, meningitis, and wound infection rates, duration of hospital stay, and readmission rates were examined. RESULTS: There was no statistical difference in facial nerve function between the groups when controlling for tumor size. Likewise, there was no difference in meningitis or wound infection rates in the groups. As expected, hospital stay was significantly reduced but readmission rates were not affected. CONCLUSIONS: There are no apparent facial nerve function or infection control benefits to 1-day preoperative admission for intravenous steroids and antibiotics for patients undergoing vestibular schwannoma excision.

Anti-Bacterial Agents↗

Transcochlear repair of persistent cerebrospinal fluid leaks.

OBJECTIVE: The purpose of this study is to demonstrate the utility of a modified transcochlear obliteration of the petrous apex in repair of persistent cerebrospinal fluid (CSF) leaks. A review of temporal bone computed tomography (CT) scans and histological preparations for potential air cells leading to such leaks is also presented. STUDY DESIGN: Retrospective case review in an academic tertiary referral center. METHODS: Patients for inclusion in this study had previously undergone either a suboccipital or translabyrinthine removal of an intracranial tumor with subsequent transmastoid and middle ear obliteration of air cell tracts to stop a CSF leak. Ninety CT scans and 178 temporal bones were reviewed and assessed for peritubal and petrous apex pneumatization. RESULTS: Four patients had initial obliteration of the orifice of the eustachian tube and middle ear that failed to prevent leakage of CSF. The leak was ultimately controlled by a transcochlear petrous apicectomy. From The Ohio State University temporal bone collection, 178 specimens were available for examination. Peritubal pneumatization was found in 42% of the bones examined. The CT scans showed unilateral petrous apex pneumatization in 30% of the specimens and bilateral pneumatization in 11%. CONCLUSIONS: Continuity of air cell tracts from the petrous apex surrounding the internal auditory canal to the medial eustachian tube can provide a path for CSF rhinorrhea that is difficult to stop by conventional means. A modified transcochlear approach successfully terminated persistent leaks in four such patients.

Adult↗

Sensorineural hearing loss after occlusion of the enlarged vestibular aqueduct.

OBJECTIVE: This study aimed to report the hearing results of endolymphatic sac occlusion in patients with enlarged vestibular aqueduct syndrome. STUDY DESIGN: The study design was a multiinstitutional retrospective case series. SETTING: The study was conducted at tertiary otologic referral centers. PATIENTS: The study included 10 previously unreported patients with progressive sensorineural hearing loss and vestibular aqueducts greater than 1.5 mm in diameter on computerized tomography. INTERVENTION: Occlusion of the enlarged vestibular aqueduct was performed by means of a transmastoid surgical approach. Either intraluminal endolymphatic sac obliteration (five patients) or extraluminal extradural endolymphatic sac obliteration (five patients) was accomplished with temporalis fascia. MAIN OUTCOME MEASURES: The postoperative pure tone average (PTA) and speech discrimination scores were compared with the preoperative levels using conventional audiometry. RESULTS: Nine of 10 patients experienced some degree of sensorineural hearing loss. The median change in PTA was a loss of 21 decibels (dB), and 50% of the patients experienced a sensorineural hearing loss greater than 25 dB. Postoperative change in PTA ranged from +10 dB to -59 dB. The median change in speech discrimination score was a loss of 27.5%. Only one patient had an improvement in both speech discrimination score and pure tone averages after surgery. Patients who underwent extraluminal occlusion had a median PTA loss of 12 dB, and patients who underwent open sac occlusion had a median PTA loss of 34 dB. These were not statistically different. CONCLUSION: In this series of 10 patients, 5 had a greater than 25 dB decrease in hearing after occlusion of the enlarged vestibular aqueduct. Surgical occlusion of the enlarged vestibular aqueduct showed no significant benefit in hearing preservation. The otologic surgeon is alerted to the potential for severe sensiorineural hearing loss after occlusion of the enlarged vestibular aqueduct.

Adolescent↗

Assessment of internal auditory canal tumors: a comparison of contrast-enhanced T1-weighted and steady-state T2-weighted gradient-echo MR imaging.

BACKGROUND AND PURPOSE: Although contrast-enhanced T1-weighted MR imaging is the standard of reference for diagnosing tumor in the cerebellopontine angle, high-resolution T2-weighted imaging may show more details of the seventh and eighth cranial nerve branches, resulting in more accurate tumor volume measurements. The purpose of this study was to compare two MR sequences for their ability to delineate internal auditory canal tumors. METHODS: Twenty-seven ears in 21 patients with 16 confirmed schwannomas were studied with the 3D T2-weighted prototype segment-interleaved motion-compensated acquisition in steady state (SIMCAST) and the T1-weighted contrast-enhanced spoiled gradient-echo (SPGR) techniques. Twenty-eight axial sections were acquired using parameters of 17/3.3 (TR/TE), a 40 degrees flip angle, a 20 x 15-cm or 22 x 16-cm field of view (FOV), a 512 x 256 matrix, and a 0.4- or 1.2-mm section thickness for the SIMCAST technique, and 30/4.2, a 30 degrees flip angle, a 20 x 20-cm FOV, a 512 x 288 matrix, and a 1.5-mm section thickness for the SPGR technique. Tumor appearance and depiction of surrounding anatomy, including the cranial nerves, were evaluated. Tumor volumes were measured by manual tracing. RESULTS: Both sequences clearly identified tumors that ranged in size from 0.06 to 3.0 cm3. Measurements on both sequences agreed, on average, within 14%. The information from both sequences was complementary. SIMCAST usually delineated the CSF spaces better, whereas SPGR more clearly showed the tumor/brain boundary. CONCLUSION: SIMCAST and SPGR are suitable for tumor detection and volume measurements. SPGR has somewhat better contrast, but SIMCAST excels at depicting the surrounding anatomy and tumor involvement of the seventh and eighth cranial nerves.

Adolescent↗

The learning curve in vestibular schwannoma surgery.

OBJECTIVE: This study aimed to examine the effect of surgical team experience on facial nerve function and complication rate in vestibular schwannoma surgery. STUDY DESIGN: The study design was a retrospective analysis of a case series. SETTING: The study was conducted at a tertiary referral center. PATIENTS: One hundred sixty consecutive patients undergoing vestibular schwannoma excision participated. INTERVENTION: Surgical excision of vestibular schwannoma via a translabyrinthine, middle cranial fossa, suboccipital, or combined approach was performed. MAIN OUTCOME MEASURES: Facial nerve function (House-Brackmann score) and complication rates including cerebrospinal fluid leak and meningitis compared by groups of 20 patients were measured. RESULTS: There was a statistically significant improvement in the number of patients achieving a House-Brackmann grade I result between the first 20 patients (35% House-Brackmann grade 1) and the ensuing 7 groups of 20 patients (74% House-Brackmann grade 1) by chi2 analysis. When considering House grades I and II together, there was no statistically significant difference in facial nerve function in the first 20 patients (80%) compared to the last 7 groups of 20 patients (88%) by Tukey's pairwise comparisons (p = 0.245). Mean tumor size was not significantly different in the groups studied (p = 0.54). The total cost of patient care declined over the study period; however, the wide case-to-case variance made it so that this trend was not statistically significant (p = 0.448). CONCLUSIONS: A learning curve of 20 patients was demonstrated by this study to have been necessary for attaining acceptable standards in the surgical removal of vestibular schwannomas by a new surgical team. The findings of this study may have implications for patient care and surgeon training.

Adolescent↗

Clinical manifestations of mutations in the neurofibromatosis type 2 gene in vestibular schwannomas (acoustic neuromas).

Vestibular schwannomas (acoustic neuromas) continue to cause significant facial nerve and hearing morbidity, despite marked improvement in diagnosis and treatment. Mutation of a tumor-suppressor gene on human chromosome 22 has been found to be associated with vestibular schwannoma formation. The central hypothesis of this study is that specific mutations in the neurofibromatosis type 2 (NF2) gene may produce specific clinical characteristics or phenotypic expressions. The purposes of this investigation are: 1. to determine what proportion of vestibular schwannomas from patients with spontaneous unilateral and familial bilateral schwannomas have mutations present within the NF2 gene; 2. to determine whether specific types of mutations are associated with a specific clinical manifestation of this disease; and 3. to further define the relationship between newly discovered mutations within the NF2 tumor-suppressor gene and possible clinical applications of this knowledge to advance diagnosis and treatment of patients with NF2 and spontaneous vestibular schwannomas. DNA from 61 schwannomas (29 unilateral vestibular schwannomas and 32 from patients with bilateral vestibular schwannomas [NF2]) were examined, and 33 unique mutations were identified. Significant differences were found in the frequency, distribution, and type of mutation between the NF2 schwannomas and the spontaneous vestibular schwannomas. Three clinical subtypes of NF2 were identified. In tumors from 28 patients, no mutations were identified. Of the 33 mutations identified in the NF2 gene, 30 were likely to result in loss of tumor-suppressor function from protein truncation; however, three milder mutations termed missense mutations were associated with milder clinical manifestations of the disease and had a slower estimated growth rate. Variable clinical presentation in patients whose tumors had severe or truncating types of mutations suggest that factors in addition to the mutation class are likely to be responsible for a portion of the clinical expression of disease. New diagnostic options are now available for NF2 that will improve the likelihood of hearing and facial nerve preservation and ultimately have significant impact on the management of vestibular schwannomas.

Adult↗

Middle fossa transpetrosal approach for petroclival and brainstem tumors.

OBJECTIVE: The purpose of the study was to demonstrate the utility of the middle fossa transpetrosal approach with anterior petrosectomy for difficult-to-access petroclival and pontine lesions. STUDY DESIGN: Retrospective case review in academic tertiary referral center. METHODS: Patients for inclusion had pontine and prepontine lesions of the petroclival region. Middle fossa transpetrosal approach with anterior petrosectomy with excision or biopsy of the lesion was performed. The main outcome measure was postoperative neurologic status including motor and cranial nerve function. RESULTS: No patient experienced neuromuscular compromise or cranial nerve deficits as a direct result of the surgical procedure. Complications consisted of a subdural temporal lobe hemorrhage and one case of cerebrospinal fluid rhinorrhea. CONCLUSIONS: The middle fossa transpetrosal approach with anterior petrosectomy was utilized for five patients with petroclival or pontine tumors. In this small series, it served well to spare cranial nerves and allowed avoidance of serious vascular injury. To our knowledge, this is the first reported use of this procedure for pontine venous angiomas.

Adolescent↗

Intracranial tumors mimicking benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo is a common type of vertigo seen by the otolaryngologist; however, intracranial tumors can mimic benign paroxysmal positional vertigo in their presentation. A review of patients seen in the Department of Otolaryngology at The Ohio State University between July 1992 and August 1996 identified five patients with intracranial pathologic conditions mimicking benign paroxysmal positional vertigo. These patients were first seen with episodic vertigo associated with positional change. Failure of the symptoms to respond to the particle repositioning maneuver or the finding of associated auditory or neurologic symptoms prompted further evaluation by magnetic resonance imaging of the brain, which revealed intracranial pathologic conditions including two meningiomas, a vestibular schwannoma, a glioma, and a lipoma. These findings suggest that patients seen with symptoms like those of benign paroxysmal positional vertigo who do not show improvement after undergoing the particle repositioning maneuver or those who describe associated auditory or neurologic symptoms should have magnetic resonance imaging done to rule out intracranial pathologic conditions. Additionally, benign paroxysmal positional vertigo and intracranial tumors may coexist.

Adult↗

Endolymphatic sac occlusion for the enlarged vestibular aqueduct syndrome.

OBJECTIVE: To test the efficacy of occlusion of the enlarged vestibular aqueduct to treat the progressive sensorineural hearing loss associated with the enlarged vestibular aqueduct (EVA) syndrome. STUDY DESIGN: Prospective controlled study. SETTING: Tertiary care referral center. PATIENTS: Sixteen consecutive patients (29 affected ears) with progressive sensorineural hearing loss and vestibular aqueducts >1.5 mm in diameter without other inner ear anomalies participated in this study. INTERVENTION: In 10 patients with progressive hearing loss, the EVA was occluded in the ear with worse hearing by placing a fascia graft between the posterior fossa dura overlying the endolymphatic sac and intraosseous duct and the posterior semicircular canal without opening the endolymphatic sac. In the operative ears, serial postoperative audiograms were compared with the contralateral ear in patients with bilateral EVA and with the other nonoperated control ears. MAIN OUTCOME MEASURES: The rate of decline of pure-tone average and speech discrimination before surgery in the operated ear was compared with the rate of decline postoperatively in the same ear. The rates of decline in the nonoperated contralateral ear from the same patient and the nonoperated control ears from other patients were also used for comparison with the postoperative rate of decline in the operated ears. RESULTS: There was no statistically significant change in the rate of hearing loss in patients undergoing occlusion of the EVA. CONCLUSIONS: Extraluminal soft-tissue occlusion of the EVA appears to be a safe procedure but has not yet been shown to be significantly effective in altering the sensorineural hearing loss accompanying the EVA syndrome. Further surgical intervention does not appear warranted until such time that longitudinal follow-up shows sufficient evidence of efficacy of the procedure.

Adolescent↗

Particulate matter in the posterior semicircular canal.

The pathoetiology of benign paroxysmal positional vertigo (BPPV) is controversial. Particulate matter within the posterior semicircular canal has been identified intraoperatively in patients with BPPV but has also been reported in non-BPPV patients at the time of translabyrinthine surgery (Parnes LS, McClure JA. Free-floating endolymphatic particles: a new operative finding during posterior semicircular canal occlusion. Laryngoscope 1992;102:988-92; Schuknecht HF, Ruby RRF. Cupulolithiasis. Adv Otorhinolaryngol 1973;20: 434-43; Kveton JF, Kashgarian M. Particulate matter within the membranous labyrinth: pathologic or normal? Am J Otol 1994;15:173-6). The nature of the particulate matter remains unknown. The purpose of this study was to prospectively examine the posterior semicircular canal of patients with and without a clinical history of BPPV for the presence of particulate matter. Seventy-three patients without BPPV symptoms undergoing labyrinthine surgery (vestibular schwannoma excision or labyrinthectomy) and 26 patients with BPPV undergoing the posterior semicircular canal occlusion procedure were compared. Additionally, 70 archived temporal bones without a history of BPPV were examined microscopically for the presence of particulate matter within the lumen of the membranous labyrinth. No particles were observed intraoperatively in any of the 73 patients without a history of BPPV. Particulate matter was observed in 8 of 26 patients at the time of the posterior semicircular canal occlusion procedure for intractable BPPV. Of the 70 temporal bones examined, 31 did not show significant postmortem changes and also did not demonstrate cupulolithiasis or canalithiasis. Particulate matter from within the membranous posterior semicircular canal was removed from one patient at the time of posterior semicircular canal occlusion for intractable BPPV symptoms and was examined by scanning electron microscopy. The particulate matter appeared morphologically consistent with degenerating otoconia. These data show a statistically significant association between the presence of particles within the posterior semicircular canal in this study and the symptom complex of BPPV.

Ear, Inner↗

Inner and middle ear hyperbaric oxygen-induced barotrauma.

Patients receiving hyperbaric oxygen (HBO) therapy can sustain inner and middle ear barotrauma. The purpose of this study is to define the incidence and significance of HBO-related barotrauma, in addition to establishing guidelines for prophylactic myringotomy or tympanostomy tube placement. Thirty patients were stratified into two groups (those able to autoinflate and those unable to autoinflate the middle ear) and barotrauma was assessed by otoscopy, tympanometry, high-frequency audiometry, and distortion product otoacoustic emission (DPOAE) testing. Ten of 11 patients (91%) from the noninflater group suffered middle ear barotrauma, and seven of 19 patients (37%) from the autoinflater group sustained middle ear barotrauma. Patients unable to autoinflate the middle ear were shown to have a higher incidence and greater severity of barotrauma than patients able to autoinflate. Pretreatment pressure-equalizing tubes or myringotomies should be considered for patients undergoing HBO therapy who have an artificial airway or have eustachian tube dysfunction and have failed conservative medical intervention. A significant change in DPOAEs (loss of emissions over a 1-kHz range) was found in four of 15 autoinflaters (27%) and two of seven noninflaters (29%). There was no significant difference between the groups. The decrease in DPOAEs was not associated with a change in conventional audiometry.

Barotrauma↗

Hemangioma of the temporal bone in a patient presumed to have Ménière's syndrome.

This case report describes a patient with a facial nerve hemangioma of 8 years' duration that initially caused most of the symptoms of Ménière's syndrome: fullness, sensorineural hearing loss, dizziness, tinnitus, and disruption of balance. The hearing loss was in the high-frequency range (> or = 3,000 Hz); typically, the initial hearing loss in Ménière's syndrome is in the low-frequency range. Mild facial nerve weakness and punctate keratitis due to corneal exposure appeared 8 years later. Contrast-enhanced magnetic resonance imaging and high-resolution computed tomography depicted the lesion and made preoperative diagnosis possible. With meticulous surgical removal of the tumor, which was intertwined with the facial nerve, facial nerve function was preserved.

Cranial Nerve Neoplasms↗