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Biomedical subjects

W E Hitselberger

Publications and source records attributed to W E Hitselberger.

At least 37 records · Page 2Linked to original sources
PubMed1994

Translabyrinthine removal of large acoustic neuromas.

Several surgical approaches to the cerebellopontine angle and internal auditory canal have been developed for the removal of acoustic neuromas. The choice of an approach may be influenced by hearing levels and tumor size. We reviewed the records of the primary translabyrinthine removal of 167 large (> or = 4 cm) acoustic neuromas performed between 1982 and 1990. Patients ranged in age from 15 to 83 years, with a mean of 43 years (male, 49%; female, 51%). Total removal was achieved in 95%. The facial nerve was preserved anatomically intact in 91%. At follow-up (mean, 2.1 yr), facial nerve function was acceptable (Grades I-IV) in 75% and good (Grades I-II) in 42%. Vascular complications occurred in 4.8%; however, there were no deaths. A cerebrospinal fluid leak occurred in 9.6% of cases, and meningitis occurred in 8.3%. In patients with large tumors where there is little chance to preserve preoperative hearing, we have successfully used the translabyrinthine approach for total tumor removal. The advantages and disadvantages of both the translabyrinthine and suboccipital approaches are discussed.

Adolescent↗
PubMed1994

Technical modifications to the middle fossa craniotomy approach in removal of acoustic neuromas.

With the increased use of gadolinium-enhanced magnetic resonance imaging studies to detect acoustic neuromas, smaller tumors are discovered more frequently. The middle fossa craniotomy approach for removal of small tumors is ideal for hearing preservation. The authors report hearing preserved at or near the preoperative levels in 71 percent of a series of 24 consecutive patients in whom the middle fossa craniotomy approach was employed. Several technical modifications, including more extensive bony exposure medially, tumor dissection in a medial-to-lateral direction, and topical application of papaverine to the cochlear nerve at the modiolus, have enhanced the ability to preserve hearing.

Adolescent↗
PubMed1993

The middle fossa transpetrous approach for petroclival meningiomas.

Seventeen patients with petroclival meningioma were operated on through a middle fossa transpetrous approach. This approach exposes the anterior cerebellopontine angle through a middle fossa craniotomy with removal of the petrous apex medial to the cochlea and petrous carotid artery. This approach may be enlarged by transection of the superior petrosal sinus and tentorium. The surgical technique and application of the middle fossa transpetrous approach for petroclival meningiomas is presented.

Journal Article↗
PubMed1993

Auditory brainstem implant: I. Issues in surgical implantation.

Most patients with neurofibromatosis type 2 (NF2) are totally deaf after removal of their bilateral acoustic neuromas. Twenty-five patients with neurofibromatosis type 2 have been implanted with a brainstem electrode during surgery to remove an acoustic neuroma. The electrode is positioned in the lateral recess of the fourth ventricle, adjacent to the cochlear nuclei. The present electrode consists of three platinum plates mounted on a Dacron mesh backing, a design that has been demonstrated to be biocompatible and positionally stable in an animal model. Correct electrode placement depends on accurate identification of anatomic landmarks from the translabyrinthine surgical approach and also on intrasurgical electrophysiologic monitoring. Some tumors and their removal can result in significant distortion of the brainstem and surrounding structures. Even in the absence of identifiable anatomic landmarks, electrode location can be adjusted during surgical placement to find the location that maximizes the auditory evoked response and minimizes activation of other monitored cranial nerves. Stimulation of the electrodes produces auditory sensations in most patients, with results similar to those of single-channel cochlear implants. A coordinated multidisciplinary team is essential for successful application of an auditory brainstem implant.

Brain Stem↗
PubMed1992

Retrolabyrinthine vestibular nerve section: evaluation of technical modification in 143 cases.

Selective vestibular nerve section is effective in relieving intractable vertigo while preserving hearing. Histologic study demonstrated overlap of the cochlear and vestibular fibers at the cochleovestibular cleavage plane within the posterior fossa. In the hopes of improving surgical results by sectioning these overlapping vestibular fibers, the technique of sectioning the vestibular division of the eighth nerve was modified to include a small portion of the cochlear division. We have evaluated 143 cases of retrolabyrinthine vestibular nerve section in which this technical modification was employed. A patient questionnaire was used to examine control of vertigo as well as changes in tinnitus, unsteadiness, and disability. Hearing preservation and incidence of complications were also reviewed. Resolution or improvement of vertigo occurred in 93 percent of Menièré's cases and 74 percent of non-Menièré's cases as compared to 97 percent and 68 percent, respectively, in the pre-1986 series.

Adult↗
PubMed1992

Extended middle fossa and retrolabyrinthine approaches in acoustic neuroma surgery: case reports.

Hearing conservation surgery for small acoustic neuromas is well accepted. At present, two approaches are primarily used: the suboccipital and the middle fossa. The middle fossa approach to the internal auditory canal has the advantage of using bony landmarks to identify and protect the facial nerve. Because of anatomic constraints presented by the superior semicircular canal however, its uses are limited to intracanalicular tumors or tumors protruding only slightly into the cerebellopontine angle. By extending the approach through the superior semicircular canal, a wide access to the cerebellopontine angle can be safely obtained. In this study three procedures, two through the superior semicircular canal and one through the posterior semicircular canal, were utilized for hearing conservation surgery. By immediately sealing off the canal ends, hearing preservation was accomplished in two out of three of these cases. The dictum that labyrinthine opening invariably leads to anacusis should be reconsidered. By utilizing approaches through the semicircular canal, it is possible that morbidity from this surgery may be reduced.

Cerebellar Neoplasms↗
PubMed1992

Acoustic tumors: effect of surgical removal on tinnitus.

Tinnitus is common in patients with acoustic tumors and may be the initial symptom leading to diagnosis. We might anticipate that tumor removal would alleviate preoperative tinnitus. However, few have studied this systematically. Further, the effect of tumor removal in those with no preoperative tinnitus has rarely been examined. In this study, a questionnaire was sent retrospectively to patients who had undergone surgical removal of an acoustic tumor, addressing the characteristics of tinnitus, and asking whether surgery had directly affected tinnitus. A total of 134 questionnaires were returned. Those who indicated preoperative tinnitus tended to show small but statistically significant improvements in the perceived severity of the tinnitus after surgery, although the symptom rarely resolved entirely. Those with no preoperative tinnitus have an approximately 50 percent chance of developing it following surgery.

Adult↗
PubMed1991

The treatment of small acoustic tumors: now or later?

Prior to the advent of microneurosurgery, the operative mortality for acoustic tumor removal was high and management often consisted of observation until sufficient symptoms warranted removal. The treatment of these tumors has evolved, and recent introduction of gadolinium-enhanced magnetic resonance imaging (MRI) allows the diagnosis of very small intracanalicular acoustic tumors before hearing has been significantly affected. For such tumors, some surgeons advocate the premicrosurgical philosophy of observation rather than removal. Our results of small acoustic tumor removal with attempt at hearing preservation were reviewed. From 1961 to June 1989, 39 acoustic tumors 0.5 cm or less were removed by the middle fossa approach. Measurable hearing was preserved in 67%, and facial function 1 year postoperatively was normal or nearly normal in 97%. There was no other permanent operative morbidity. Given our results, early surgical removal of small acoustic tumors is advocated.

Adolescent↗
PubMed1990

Auditory brain stem implant: effect of tumor size and preoperative hearing level on function.

The auditory brain stem implant is an investigational device designed to provide hearing sensations to patients without functioning auditory nerves. We analyzed results from 17 implants in 15 patients to determine if tumor size or preoperative hearing level might be related to proper device function. We found no significant correlation between preoperative hearing level or tumor size and device function. We also found no significant correlation between preoperative hearing level and tumor size in these 15 patients.

Adolescent↗
PubMed1990

Cochlear nucleus anatomy related to central electroauditory prosthesis implantation.

The central electroauditory prosthesis is now used to stimulate the cochlear nuclei to obtain auditory perception in patients with bilateral cochlear nerve transection who are undergoing bilateral acoustic tumor removal. In this study, we used fixed cadaver specimens to identify visible landmarks for accurate placement of the central electroauditory prosthesis through a combined suboccipital-translabyrinthine opening. Histologic features of the regions of probable implantation of the central electroauditory prosthesis were also investigated. We found that the following landmarks might have surgical significance: (1) the tenia of the inferior velum of the fourth ventricle, which crosses the surface of the ventral cochlear nucleus and the vestibulocochlear nerve; (2) the angle between the vestibulocochlear and glossopharyngeal nerves; and (3) the foramen of Luschka. It is suggested that an incision be made in the tenia for insertion of the prosthesis into the lateral recess and eventual placement on the ventral cochlear nucleus surface. To study regions of potential stimulation, we injected ink into different sites on the exposed surface of the cochlear nuclei. We then histologically examined neuronal populations adjacent to the sites. We found that a portion of the ventral cochlear nucleus localized within the lateral recess might be the most appropriate location for placement of the central electroauditory prosthesis.

Cochlea↗
PubMed1990

Hearing preservation after acoustic tumor removal: long-term results.

This report examines the durability of preserved postoperative hearing in 25 middle fossa acoustic tumor patients with a minimum follow-up of 3 years. The mean follow-up time for this group was more than 8 years, with a maximum of almost 20 years. The initial postoperative audiogram was compared to the most recent audiogram for each patient, with change in the nonoperated ear serving as the control. Fourteen of the patients (56%) had a significant loss of the preserved hearing in the operated ear over time. The mean loss of speech discrimination was 25%, and the mean loss of speech reception threshold was 12 dB. Only one of the 14 patients had a similar loss in the contralateral ear. No recurrent tumors were identified. Good preoperative hearing is an obvious criterion for selection of candidates for hearing preservation surgery. Results of this study emphasize that a good initial postoperative hearing level is necessary to offset the potential deterioration of hearing that may occur over time.

Adolescent↗
PubMed1990

Middle fossa decompression of the internal auditory canal in acoustic neuroma surgery: a therapeutic alternative.

Unilateral acoustic neuromas in only-hearing ears and bilateral acoustic neuromas (NF-2) are separate entities, but both pose a common problem because surgical removal has the potential to leave the patient totally deafened. A middle fossa decompression of the internal auditory canal (IAC) was performed in 8 patients (5 with NF-2 tumors and 3 with neuromas in an only-hearing ear). In 5 of the 8, the speech discrimination scores at the 6-month follow-up were better than preoperative scores. After 6 months, however, hearing regressed at variable rates. Although not a definitive therapeutic treatment, decompression of the IAC appears to improve and perhaps prolong useful hearing, which gains valuable time for rehabilitation. Rigid follow-up by computed tomography scans or magnetic resonance imaging is essential.

Adult↗
PubMed1990

Sex hormone receptors in acoustic neuromas.

We performed quantitative assays for estrogen, progesterone, and testosterone receptors in 19 acoustic neuroma specimens from ten men and nine women. No patient received preoperative or intraoperative glucocorticoids, mineralocorticoids, or sex hormones. All tumors were unilateral and removed by the translabyrinthine approach. No tumor specimen was positive for estrogen or testosterone receptors. Three of ten men and seven of nine women had tumors positive for progesterone receptors (10 fmol/mg cytosol protein or greater). This between-sex difference was of borderline significance by the Mann-Whitney U test (p = 0.08). This finding indicates the need for further investigations of endocrinologic therapy as a possible treatment of acoustic neuromas.

Female↗
PubMed1989

Acoustic tumor surgery. Prognostic factors in hearing conversation.

Preoperative selection criteria for hearing conservation surgery in patients with acoustic tumors continues to be unresolved. The level of hearing that is worth saving is still debatable. However, most acoustic tumor surgeons agree that hearing preservation is less likely the larger the tumor. We reviewed the results of 106 middle fossa acoustic tumor removals with attempted hearing preservation. Measurable postoperative hearing remained in 59% of 97 cases analyzed for postoperative hearing results. Tumor size, preoperative auditory brain-stem response, and preoperative electronystagmography were found to be useful in predicting successful postoperative hearing preservation. We found no correlation between the level of preoperative hearing and our ability to preserve measurable postoperative hearing. A new classification system is proposed for reporting hearing results after acoustic tumor surgery. It is based on functional hearing results and we believe it is simpler than previously proposed systems.

Audiometry↗