Atypical invasion of the temporal bone in vestibular schwannoma

Vestibular schwannomas typically present with erosion of the temporal bone that is limited to the boundaries of the internal auditory canal. Four patients with extensive erosion, excavations, and pseudosatellite defects in the petrous apex are presented. These bony changes extended anteriorly up to the level of the carotid canal. The patients did not have stigmata of neurofibromatosis type 2 and they did not have systemic bony disorders. The tumors did not show any unusual histopathologic changes. Such invasive tumors present an unusual surgical challenge compared to vestibular schwannomas with a more typical pattern of bony erosion. Radiological features and surgical considerations relevant to vestibular schwannomas with this rare presentation are discussed.

L-n-acetyl-cysteine protection against cisplatin-induced auditory neuronal and hair cell toxicity

OBJECTIVES

The aim of this study is to determine the efficacy of L-N-acetyl-cysteine (L-NAC) as a protectant for inner ear auditory sensory cells against the toxic effects of cisplatin.

STUDY DESIGN

Prospective laboratory study of the otoprotective effect of L-NAC on auditory neurons and hair cells in vitro.

METHODS

The study has two arms. The first arm evaluated the neuroprotective effect of L-NAC on early postpartum auditory ganglion cell cultures. Two culture media were used. The two media differed in that one of them was enhanced by the addition of neurotrophins (neurotrophin type 3 and brain-derived neurotrophic factor) and a growth factor (transforming growth factor-beta1). Then the survival of cisplatin-treated auditory neurons was studied before and after pretreatment with protective levels of L-NAC. The second arm of the study evaluated the effect of L-NAC on cisplatin damage initiated to auditory hair cells. Early-postpartum organ of Corti explants were grown in culture. Their rate of survival was studied after exposure to toxic levels of cisplatin. Then, survival of cisplatin-damaged hair cells was studied after they were pretreated with L-NAC.

RESULTS

Pretreatment of cultures with L-NAC protected both auditory neurons and hair cells from the effects of exposure to toxic levels of cisplatin. This observed otoprotective effect was dose dependent.

CONCLUSIONS

Our in vitro studies have demonstrated that L-NAC protected both auditory neurons and hair cells from the toxic effects of cisplatin. Because it protects both of these inner ear structures, L-NAC may be potentially useful in protecting hearing, in general, from cisplatin-induced damage. In addition, L-NAC has low systemic and mucosal toxicity. It also has a low molecular weight that may allow it to readily cross the round window membrane. All these characteristics make it potentially suitable for transtympanic application for the prevention of the ototoxicity of cisplatin in vivo.

Evaluation of esterified hyaluronic acid as middle ear-packing material

OBJECTIVE

To evaluate the efficacy of esterified hyaluronic acid (MeroGel) as a middle ear (ME)-packing material.

DESIGN

Randomized controlled trial.

MATERIAL

Twenty-four guinea pigs.

INTERVENTION

Group 1, MeroGel-treated animals (n = 10), bilateral wounding of ME mucosa with 5 of the animals receiving the MeroGel packing in the left ME and 5 of the animals receiving MeroGel in the right ME; group 2, absorbable gelatin sponge-treated animals (n = 10), with the same experimental protocol as in group 1 except that the absorbable gelatin sponge was the packing material; group 3, untreated animals (n = 4), unilateral wounding of the left ME mucosa in 2 animals and in 2 animals in the right ME, with no packing material. Auditory brainstem recordings were performed for all groups before the ME operation and 5 days and 6 weeks after the operation.

RESULTS

Auditory brainstem response recordings at postoperative day 5 showed that all ears with ME packing had hearing losses in the frequency range of 500 to 4000 Hz. The recovery of hearing acuity at postoperative week 6 was significantly better in group 1 (MeroGel-treated) guinea pigs compared with group 2 (the absorbable gelatin sponge-treated) animals. In group 2 animals, 20% of the packing material remained in the ME cavities and new bone formation was observed, while in group 1 animals, there was less packing material in the ME and no formation of new bone.

CONCLUSIONS

MeroGel is a nonototoxic packing material with a high level of biocompatibility for ME mucosa; it is an effective supportive material following ME surgery and is easily expelled from the ME cavity.

Round window membrane delivery of L-methionine provides protection from cisplatin ototoxicity without compromising chemotherapeutic efficacy

Cisplatin (cis-diamminedichloroplatinum(II) (CDDP)) is a widely used, highly effective, oncolytic agent that has serious ototoxic side-effects. To test the effectiveness of local delivery, of L-methionine (L-Met) as an otoprotective agent against CDDP ototoxicity, we used a rat model of a highly metastatic breast cancer tumor, i.e. Fisher 344 rats implanted with MTLn3 breast cancer cells. Four experimental groups were evaluated--I: untreated; II: CDDP-treated (three dosages); III: systemically-delivered L-Met + CDDP-treated; IV: locally delivered L-Met + CDDP-treated. The integrity of the outer hair cells (OHCs) was determined using scanning electron microscopy (SEM); hearing was assessed by recording auditory brainstem responses (ABRs) at multiple frequencies. The chemotherapeutic effectiveness of CDDP was quantified by measuring changes in tumor mass and the presence of tumor metastasis. L-Met provided otoprotection of the OHCs against CDDP toxicity in the cochleae of rats following either systemic (III) or local (IV) administration. The ABRs were unchanged in each of the L-Met protection Groups (III and IV) and in the untreated animals of Group I. Treatment with CDDP only (II) induced significant hearing losses at both 16 and 18 kHz when compared to ABRs of untreated rats(I). CDDP was effective in controlling the MTLn3 initiated breast cancer tumors in the CDDP-treated (II) and the local L-Met protection, CDDP-treated (IV) Groups. In contrast, the tumors in the systemic L-Met protection, CDDP-treated Group (III) were not controlled by the CDDP treatment regime. This study demonstrates that local delivery of L-Met to the scala tympani of the cochlea via the round window membrane (IV) provides effective protection against CDDP ototoxicity without compromising its ability to control a highly metastatic form of cancer.

Aneurysmal bone cyst of the temporal bone

OBJECTIVE AND IMPORTANCE

Aneurysmal bone cysts (ABC) are benign bone neoplasms which typically involve the spine and long bones. We present a rare case of an ABC in the temporal bone with significant cerebellar compression.

CLINICAL PRESENTATION

The patient was a young boy who presented with several weeks of left posterior auricular pain. Computed tomography, magnetic resonance imaging and angiogram showed an expansile bone neoplasm involving the left petrous temporal bone.

INTERVENTION

A retrosigmoid-transmastoid craniectomy was performed, and total removal of the bone lesion was achieved. The pathological examination revealed the diagnosis of ABC.

CONCLUSION

The postoperative course was uneventful, and the imaging studies demonstrated total removal of the neoplasm. This case represents the imaging and surgical management of a rare ABC in the temporal bone. This diagnosis should be considered in the differential of bone neoplasms in this region.

Split calvarial graft cranioplasty for the prevention of headache after retrosigmoid resection of acoustic neuromas

OBJECTIVE

This study describes the technique and efficacy of split calvarial graft cranioplasty for the reconstruction of retrosigmoid/suboccipital defects following surgery for acoustic neuromas.

STUDY DESIGN

A prospective study of the technique of split calvarial graft cranioplasty, its postoperative healing, and incidence of postoperative headache.

METHODS

The technique requires splitting of the craniotomy bone flap into outer and inner table bone grafts. The combination of both bony grafts allows the coverage of a wider area of posterior fossa dura. This technique was used in 18 patients. All patients were followed for a minimum of 6 months. Eleven of 18 patients were followed for 1 year or longer. Four patients had three-dimensional computed tomography of their skull and area of split calvarial bone graft.

RESULTS

One of 18 patients had a persistent disabling headache at 1 year postoperatively. A natural contour of the retrosigmoid area was achieved in all patients. Three-dimensional computed tomography scan, obtained 6 months postoperatively, showed total coverage of the retrosigmoid area and fusion of the bone flap to the surrounding skull.

CONCLUSION

The technique of split calvarial grafting of posterior fossa defects is a feasible, safe, and effective way of separating the nuchal musculature and posterior fossa dura. The technique also allows the restoration of the contour and bony covering of the retrosigmoid area. The technique is a simple alternative to other types of cranioplasties aimed at reducing the incidence of postoperative headache in patients with acoustic neuromas.

Bone cement reconstruction of the ossicular chain: a preliminary report

OBJECTIVE

To determine the feasibility and efficacy of using a bone cement, Oto-Cem, to reconstruct the ossicular chain.

STUDY DESIGN

Prospective clinical trial on nine consecutively chosen adult patients with ossicular chain defects.

PATIENTS AND SETTING

Nine patients with ossicular chain defects involving the long process of the incus were treated at the Carolina Ear and Hearing Clinic. The ossicular chain was reconstructed using bone cement by itself or in conjunction with a stapes prosthesis.

MAIN OUTCOME MEASURES

Preoperative audiograms were compared with audiograms 3, 6, and 12 months after reconstruction.

RESULTS

There was a mean pure-tone average (PTA) improvement of 15 dB in patients undergoing incus to stapes suprastructure reconstruction with the bone cement. The incus to mobile footplate reconstruction (using a stapes prosthesis attached to the newly reconstructed incus) resulted in a 34-dB PTA postoperative improvement. Two of the three patients with incus to oval window repairs experienced a 10-dB improvement in PTA. One of the three patients experienced a loss in speech discrimination and a 2-dB loss in PTA.

CONCLUSIONS

Despite the limited number of patients, this preliminary study demonstrates the effectiveness of Oto-Cem in reconstructing a foreshortened incus. There was a substantial hearing improvement in all but one patient in the incus to stapes or the incus to footplate categories.

Mammalian auditory hair cell regeneration/repair and protection: a review and future directions

Regeneration/repair and protection of auditory hair cells and auditory neurons is an exciting, rapidly evolving field. Simultaneous developments in the fields of otobiology and surgical otology have led to new and exciting possibilities in inner ear medicine and surgery; specifically, the treatment or prevention of a variety of types of hearing losses in the foreseeable future. Sensorineural hearing loss in humans is commonly associated with a loss of auditory hair cells. It has been generally accepted that hearing loss resulting from hair cell damage is irreversible because the human ear has been considered to be incapable of regenerating or repairing these sensory elements following severe injury. An organ of Corti explant study has shown that it is possible to initiate the regeneration/repair of mammalian hair cells. In this study, ototoxin-damaged organ of Corti explants from juvenile rats were treated with a combination of retinoic acid (10-8M) and fetal calf serum (10%). TGF-alpha has been identified as a growth factor capable of evoking auditory hair cell regeneration/repair in ototoxin-damaged organ of Corti explants. Preliminary in vitro experiments with juvenile rat organ of Corti explants and in vivo studies in the cochleae of adult guinea pigs indicate that pretreatment followed by continuous treatment of the inner ear with a combination of retinoic acid and TGF-alpha can protect the auditory hair cells from the ototoxic effects of aminoglycosides. Because the integrity of spiral ganglion neurons is also essential for normal auditory function, there is a parallel series of in vitro and in vivo studies of the effects of neurotrophic factors on the survival of auditory neurons and the regeneration of injured neuronal processes. Clinical studies have demonstrated that it is now possible to perform surgeries on the inner ear, i.e., partial or total labyrinthectomies, and maintain hearing. The field of cochlear implantation has also provided insights into both the short- and long-term effects of cochlear fenestration on inner ear function. Administration of growth factors to the inner ears of animals is now possible with the use of implanted catheters and miniature infusion pumps. These advances suggest that localized application of drugs to the human inner ear may be feasible. The aim of this paper has been to provide an overview of advances in the study of the biology of auditory hair cells and auditory neurons, as well as recent relevant surgical advances. Taken together, these advances in otobiology and surgery will, in the future, be combined to devise new and innovative treatments for inner ear disorders.

Papillary endolymphatic sac tumors: CT, MR imaging, and angiographic findings in 20 patients

PURPOSE

To determine the computed tomographic (CT), magnetic resonance (MR) imaging, and angiographic findings of papillary endolymphatic sac tumors.

MATERIALS AND METHODS

Clinical and imaging studies in 20 patients (aged 17-65 years) with histopathologically proved papillary endolymphatic sac tumors were retrospectively reviewed. Patients underwent CT (n = 18), MR imaging (n = 15), or angiography (n = 12). CT scans were evaluated for bone erosion and calcification; MR images, for signal intensity, enhancement patterns, and flow voids; and angiograms, for tumoral blood supply.

RESULTS

All tumors were destructive and contained calcifications centered in the retrolabyrinthine region at CT. The MR imaging appearance varied with lesion size; 12 of 15 tumors showed increased signal intensity at T1-weighted imaging. The high-signal-intensity area was circumferential in lesions 3 cm or smaller and was scattered throughout the lesion in advanced tumors. Only tumors larger than 2 cm had flow voids. The blood supply arose predominantly from the external carotid artery. Large tumors had additional supply from the internal carotid and posterior circulation.

CONCLUSION

Papillary endolymphatic sac tumors are destructive, hypervascular lesions that arise from the temporal bone retrolabyrinthine region. Increased signal intensity at unenhanced T1-weighted MR imaging is common and may help distinguish these lesions from more common, aggressive temporal bone tumors.

Aggressive papillary tumors of the temporal bone: an immunohistochemical analysis in tissue culture

Aggressive papillary tumors of the temporal bone are neoplasms that are locally invasive and destructive. Previously classified on histologic study as middle ear adenomas or adenocarcinomas, observational evidence suggested that they arose from endolymphatic sac. To evaluate this hypothesis, we established a tissue culture from cells derived from such a papillary tumor and compared immunohistochemical stains of the original tumor with stains on endolymphatic epithelium. Similarities in expression of neuroectodermal antigens were observed. Similar staining antigens in cells derived from tumor and the endolymphatic sac provide evidence that epithelium from endolymphatic sac is the site of origin for these aggressive neoplasms. In tissue culture the cells remain contact inhibited and dependent on serum or growth factors with survival beyond the expected senescence at 30 to 50 generations. Therefore the cell culture technique provides a model for study of the disruption of growth control and invasive properties of this tumor.

Aggressive papillary tumors of the endolymphatic sac: clinical and tissue culture characteristics

Aggressive papillary tumors of the temporal bone are neoplasms that were recently re-classified as tumors of the endolymphatic sac. They typically invade the mastoid bone and otic capsule and can grow into the petrous apex. The authors have treated three patients with this rare neoplasm and grown one of the tumors in tissue culture. This report reviews the clinical presentation in the three patients and the immunohistochemical staining characteristics of the tumor and tumor culture as compared to those of the endolymphatic sac. Findings support the hypothesis that aggressive papillary lesions of the temporal bone arise from the endolymphatic sac. Additionally, it is noted that the tumor culture maintains the characteristics of the original tumor and thus provides an exciting laboratory model for further study of this rare neoplasm.

Ossiculoplasty with Polymaleinate Ionomeric Prosthesis

With the continued concern over the possible transmission of viral infections through homologous middle ear implants, there is increasing pressure to develop a truly biocompatible alloplastic middle ear prosthesis. The polymaleinate ionomer, which has been used in dentistry as a filling and luting material for more than 15 years, has recently been used to construct total and partial ossicular replacement prostheses. In an attempt to evaluate these new implants, a multicenter prospective clinical trial was initiated. To date, 92 patients have undergone implantation. The follow-up interval ranged from 3 months to 22 months. Although it is premature to discuss the long-term results, the preliminary surgical experience and audio-metric data with these implants are reviewed. From a surgical perspective, the ionomeric prostheses were easily contoured with a diamond burr and were not prone to shattering. Preliminary follow-up audiometric data were available on 80 patients (59 partial ossicular replacement prostheses and 21 total ossicular replacement prostheses). Of the 59 partial ossicular replacement prostheses the air-bone gaps (average of 500 Hz, 1 kHz, 2 kHz and 3 kHz) were as follows: 0 dB to 10 dB, 15 (25%) of 59; 11 dB to 20 dB, 20 (34%) of 59; 21 dB to 30 dB, 11 (19%) of 59; and greater than 30 dB, 13 (22%) of 59. Of the 21 total ossicular replacement prostheses the air-bone gaps were as follows: 0 dB to 10 dB, 6 (29%) of 21; 11 dB to 20 dB, 6 (29%) of 21; 21 dB to 30 dB, 5 (24%) of 21; and greater than 30 dB, 4 (19%) of 21.

Ossiculoplasty with polymaleinate ionomeric prosthesis

With the continued concern over the possible transmission of viral infections through homologous middle ear implants, there is increasing pressure to develop a truly biocompatible alloplastic middle ear prosthesis. The polymaleinate ionomer, which has been used in dentistry as a filling and luting material for more than 15 years, has recently been used to construct total and partial ossicular replacement prostheses. In an attempt to evaluate these new implants, a multicenter prospective clinical trial was initiated. To date, 92 patients have undergone implantation. The follow-up interval ranged from 3 months to 22 months. Although it is premature to discuss the long-term results, the preliminary surgical experience and audiometric data with these implants are reviewed. From a surgical perspective, the ionomeric prostheses were easily contoured with a diamond burr and were not prone to shattering. Preliminary follow-up audiometric data were available on 80 patients (59 partial ossicular replacement prostheses and 21 total ossicular replacement prostheses). Of the 59 partial ossicular replacement prostheses the air-bone gaps (average of 500 Hz, 1 kHz, 2 kHz and 3 kHz) were as follows: 0 dB to 10 dB, 15 (25%) of 59; 11 dB to 20 dB, 20 (34%) of 59; 21 dB to 30 dB, 11 (19%) of 59; and greater than 30 dB, 13 (22%) of 59. Of the 21 total ossicular replacement prostheses the air-bone gaps were as follows: 0 dB to 10 dB, 6 (29%) of 21; 11 dB to 20 dB, 6 (29%) of 21; 21 dB to 30 dB, 5 (24%) of 21; and greater than 30 dB, 4 (19%) of 21.

Erythropoietin-augmented isovolemic hemodilution in skull-base surgery. Case report

Human erythropoietin in concert with intraoperative hemodilution, tumor embolization, and surgical staging was used to manage a red blood cell mass in an anemic Jehovah's Witness patient with a hypervascular meningioma. Erythropoietin (3000 U thrice weekly) and oral iron (1300 mg daily) were given for 1 month prior to surgery, raising the hemoglobin level from 11.8 to 14.1 gm/100 ml. A posterior fossa craniectomy combined with a temporal craniectomy was then performed so that partial petrosectomy, section of the transverse sinus, incision of the tentorium, and exposure of the lesion could be carried out. The first stage of the surgery was terminated immediately prior to tumor mobilization. Isovolemic hemodilution was initiated just before the skin incision. Postoperatively, the hemoglobin concentration dropped to 11.5 gm/100 ml. The erythropoietin dose was doubled and administration of oral iron continued, leading to a hemoglobin level of 14.0 gm/100 ml at 1 month after the first operation. The tumor was embolized using superselective catheterization. The next day, at the second stage of the surgery, the tumor was extirpated, again employing isovolemic hemodilution. By the 4th postoperative day, the hemoglobin level had dropped to 9.4 gm/100 ml. The patient made an uncomplicated recovery. Erythropoietin therapy contributed substantially to the successful outcome of this case. Since erythropoietin has the potential to augment all other forms of autologous banking, its role in elective neurosurgery may become increasingly important in an era of heightened concern about heterologous transfusion.

Bilateral cholesterol granuloma: an unusual presentation as an intradural mass

The origin of the cholesterol granuloma is controversial; however, it is believed to result from an inflammatory response of the temporal bone to an obstruction of the pneumatized air cells. Hemorrhage into the air cells results in a foreign-body reaction and progressive granuloma formation. As the process develops, bone is eroded by this expansile lesion, often involving the middle ear, the petrous apex, and the cerebellopontine angle. We present the first reported case of cholesterol granulomas manifesting as bilateral intradural lesions adjacent to the temporal lobes. The fact that it presents bilaterally with sclerotic mastoids makes this presentation even more unique. Its location might cast controversy on the existing theories of development. A literature review of the cholesterol granuloma will be discussed, relating it to this patient's unusual presentation.

The transcranial translabyrinthine approach to acoustic neuromas

We originally described the transcranial translabyrinthine approach (TCTL) to acoustic neuroma. The approach is a labyrinthine dissection that is performed via the suboccipital exposure. It allows a complete and direct visualization of the internal auditory canal and the identification of the facial nerve at "Bill's bar." The TCTL enhances the suboccipital approach and adapts to its concepts of the classical transmastoid translabyrinthine approach. We hereby report our initial experience with the TCTL and present the surgical results in six additional cases. We also discuss the indications of this approach and compare it to alternative approaches that are used for the removal of large acoustic neuromas that extend laterally in the internal auditory canal.

Split-calvaria osteoplastic rotational flap for anterior fossa floor repair after tumor excision. Technical note

A split-calvaria osteoplastic rotational flap to repair the anterior fossa floor after tumor excision was devised and tested clinically. At surgery, the flap is outlined between the glabella and the vertex. After the pericranium between the glabella and the flap's anterior pole is elevated to form its pedicle, a full-thickness craniotomy is performed to expose the diploic aspect of the bone graft donor site (when the graft is relatively wide, bifrontal craniotomies may be advantageous). The diploic space is split in situ, taking care to protect the pedicle and its attachments to the osseous segment. Linear osteotomies in the outer table are created to mobilize the flap. With the flap rotated frontally, the craniotomy is completed. After tumor extirpation, the margins of the osseous segment of the flap are shaped to conform to the defect of the anterior fossa floor. Transverse osteotomies are performed so that the graft's convex curve conforms to that of the anterior fossa floor. The flap is then rotated into position. Follow-up evaluation in two patients at 22 and 30 months demonstrated bone integrity of the anterior fossa floor with graft preservation. Transient postoperative cerebrospinal fluid (CSF) rhinorrhea, which occurred in Case 1, was avoided in Case 2 by placing the osseous segment of the graft coplanar with the bone floor of the fossa. Neither patient had late meningitis or CSF rhinorrhea. The split-calvaria osteoplastic rotational flap may represent an advance toward the ideal reconstruction of the anterior cranial fossa floor.

Postoperative pain following excision of acoustic neuroma by the suboccipital approach: observations on possible cause and potential amelioration

Incisional pain and headache have been reported following cerebellopontine angle surgery via the suboccipital approach. The high incidence and severity of pain determined in a retrospective study of acoustic tumor patients prompted the present prospective study. Various modifications of the suboccipital approach have been employed in an attempt to isolate a possible cause and potential method of minimizing this problem. The results of this study suggest that pain may be caused, in part, by adherence of healing nuchal soft tissue to underlying dura following suboccipital craniectomy. The substitution of a craniotomy with bone flap replacement, which prevents such adhesion, appears to have significantly reduced the postoperative pain associated with the suboccipital approach.

Transcranial translabyrinthine approach to vestibular schwannomas

Surgeons who utilize the suboccipital approach for the removal of large vestibular schwannomas, can perform a planned labyrinthectomy from within the intracranial cavity via the suboccipital exposure. This transcranial translabyrinthine approach provides one of the major advantages of the conventional transmastoid translabyrinthine approach, namely, unambiguous identification of the facial nerve as it exits the internal auditory canal, without the need for complete mastoidectomy and labyrinthectomy. The labyrinthectomy is best performed prior to the complete exposure of the internal auditory canal. The approach requires the surgeon to identify the endolymphatic sac intracranially, then drill the temporal bone and follow the vestibular aqueduct to the utricle. The lateral and superior semicircular canal ampullae, the superior vestibular nerve, Bill's bar, and the facial nerve at the lateral end of the internal auditory canal can then be identified. After testing on multiple cadaver temporal bones, this approach was used in patients with large tumours that extended far laterally in the internal auditory canal. The steps in the technique are described in detail.

Transient evoked otoacoustic emissions: clinical applications and technical considerations

Otoacoustic emissions are defined as sound energy emitted by the cochlea. They are believed to be generated by the outer hair cells of the Organ of Corti. Several types of evoked otoacoustic emissions have been described. At present, transient-evoked otoacoustic emissions (TEOAEs) equipment is readily available commercially for clinical purposes. This paper describes our early experience with this equipment from a clinician's perspective. It reviews some of the technical problems we have encountered and their solutions. It also presents selected clinical examples where TEOAEs were particularly helpful in the clinical setting, thus illustrating the potential usefulness of this new clinical tool.

Pain after surgery for acoustic neuroma

Postoperative pain after surgery in the cerebellopontine angle (CPA) is acknowledged to occur, but is rarely taken into account as a factor in the analysis of morbidity of such surgery. It is widely acknowledged that some patients, having undergone such surgery, particularly by means of the suboccipital approach, report significant post-operative pain and headache. This study was undertaken to determine the incidence and severity of pain after excision of acoustic neuromas and to establish whether this differed between the suboccipital and translabyrinthine routes. Ninety-one percent of all patients (n = 58), who had the suboccipital approach used for removal of their tumor, were surveyed. A smaller group (n = 40), matched for tumor size, age, and sex, but in whom the translabyrinthine approach was used, was similarly studied. A standard questionnaire, designed to detect and quantify postoperative pain, was administered to each patient. Of patients who underwent tumor excision by means of the suboccipital approach, 63.7% experienced significant local discomfort and headache, whereas this was notably absent in all those who had undergone translabyrinthine excision. In view of the significant morbidity noted to follow the suboccipital approach, several modifications of the surgical technique used were devised.

Periaqueductal approach to cholesterol granulomas of the petrous apex

The periaqueductal approach for the drainage of cholesterol granulomas of the petrons apex is described. As with previously reported approaches, the periaqueductal approach takes advantage of the high pneumatization of the temporal bone in this disease. It requires dissection of the supralabyrinthine air cell tract as well as air cells medial to the posterior semicircular canal. This requires a circumferential bony dissection, skeletonization, and preservation of the vestibular aqueduct and the identification of the internal auditory canal. This periaqueductal approach preserves hearing and provides an alternative to the infralabyrinthine and infracochlear approaches when their use is precluded by variations in the temporal bone.

A new approach to serial monitoring of ultra-high frequency hearing

Early detection of drug-induced hearing loss is best accomplished by monitoring hearing at the ultra-high frequencies. Unfortunately, at these frequencies, sound pressure at the tympanic membrane (TM) critically depends on the placement of the sound source and on the size and shape of each individual external ear. Thus, presentation of the same sound may yield substantially different sound pressures in different ears. Moreover, only a slight change in the position of an earphone may yield large changes in sound pressure at the tympanic membrane. As a consequence of these characteristics, the reliability of ultra-high-frequency audiometry is poorer than at conventional audiometric frequencies. However, for the early detection of ototoxicity, it is necessary only to monitor for increases in thresholds. Accordingly, a sound-delivery system was developed which fixes the relative position of the sound source and the ear. This system ensures that sounds at the same level may be presented during different test sessions. To assess the stability of ultra-high-frequency thresholds, normal hearing subjects were tested in sessions separated by several weeks. Thresholds were obtained between 1 and 16 kHz and were found to be reliable. It is concluded that this type of system can be used for monitoring the ototoxic effects of drug therapy.

Effect of short-term intraocular pressure elevation on the rabbit electroretinogram

Pattern electroretinograms (PERGs), with a presumed ganglion cell origin, and oscillatory potentials (OPs), with a presumed inner retinal origin, are reduced in glaucoma. Flash ERGs are reduced at intraocular pressures (IOPs) greater than 60 mm Hg. A study was designed to investigate the time-course of change in PERGs, OPs, and flash ERGs after increasing the IOP of ten rabbit eyes to 35-45 mm Hg by using a suction-cup apparatus. Although flash ERG b-wave amplitude was unchanged (P = 0.32), PERGs were reduced (P less than 0.001) immediately after IOP elevation, as were OPs (P = 0.03). Both PERG and OP amplitudes returned to normal immediately after normal IOP was restored. This study showed that the rabbit is a suitable model for studying PERGs. It also suggested that moderate IOP elevation for 10 min reversibly impaired ganglion cell and inner retinal function in the rabbit, although more external function was unchanged.

Static flicker perimetry in glaucoma and ocular hypertension

The visual threshold for standard and flickering targets was determined and compared in 8 glaucoma patients, 8 glaucoma suspects and 13 normal controls. Using a Goldmann size III standard white light target, 25 points in the central 30 degrees of the visual field were tested. The location of these points was designed to reflect areas of the visual field commonly affected by glaucomatous damage. The same determinations were then repeated with the test target flickering at 25 Hz. All glaucoma patients had elevation of the visual threshold compared to normal controls for both standard and flickering targets. The absolute value of threshold elevation was not significantly different between standard and flickering lights. However, when larger targets were used, flicker thresholds were an average 8 dB higher (p less than 0.05) in the glaucoma patients compared to the normals, suggesting improved identification of glaucomatous damage with the use of larger flickering targets.

Consequences of middle ear bone dust during neurotologic surgery

Most otologists are cautioned at some point in their training that if bone dust is allowed to enter the middle ear while the mastoid is being drilled, there may be adverse consequences. Two cases of ossicular fixation and conductive hearing loss after retrolabyrinthine vestibular nerve section prompted us to examine the issue of bone dust in the middle ear. In a study of 13 temporal bones that had undergone neurotologic surgery, we found 11 that showed evidence of viable bone dust in the middle ear, and three that had ossicular fixation. Viable bone dust was always encased in a mucous membrane lining. These findings suggest that bone dust that enters the middle ear may indeed remain viable and cause ossicular fixation. The surgeon should therefore take every precaution to prevent bone dust from entering the middle ear during neurotologic procedures in which conservation of hearing is attempted.

Visual function deficits in glaucoma. Electroretinogram pattern and luminance nonlinearities

The pattern electroretinogram is abnormal in glaucoma. Part of the pattern electroretinogram may be attributed to the summation of responses to luminance increases and decreases (nonlinear luminance responses). We conducted a study to investigate the effect of glaucoma on the pattern electroretinogram component waves and to determine if the flicker electroretinogram nonlinear components are abnormal in glaucoma. We tested 35 subjects in two replications of four conditions: 10- and 20-Hz flicker, and 4- and 10-Hz pattern reversal. Only the even harmonics were recorded. The patients with glaucoma had reduced electroretinogram amplitudes for all measures relative to the normal subjects. Electroretinogram amplitudes of those suspected of having glaucoma were intermediate. The greatest amplitude reductions were for the 10-Hz flicker electroretinogram and the 4-Hz pattern electroretinogram. These results confirm pattern electroretinogram abnormalities and reveal flicker electroretinogram abnormalities in glaucoma.

Uvulopalatopharyngoplasty in a child with obstructive sleep apnea. A case report

Uvulopalotopharyngoplasty (UPPP) has been recently popularized for the treatment of snoring and sleep apnea syndrome (SAS). All reported cases so far have been adults and the use of this procedure in the pediatric age group has not as yet been reported. Obstructive sleep apnea in children has been classically treated previously either medically or by adeno-tonsillectomy. The case of a three year old child with obstructive sleep apnea secondary to a large uvula and a redundant soft palate is reported. The child was successfully treated by UPPP, and remained free of symptoms for a follow-up period of one year.

A comparison of betaxolol and timolol in open angle glaucoma and ocular hypertension

In a randomized, double-masked study, 41 patients with primary open-angle glaucoma or ocular hypertension were treated with betaxolol 0.5% or timolol 0.5% drops for 26 weeks. The average decrease in intraocular pressure (IOP) over the total study period was significant with both betaxolol (-6.3 mmHg) and timolol (-7.2 mmHg) in patients receiving no adjunctive therapy. There was no difference between betaxolol and timolol with respect to changes from baseline IOP. Significantly decreased mean brachial arterial pressure (MAP) was seen only with timolol, although the difference between the two groups was not significant. Pulse, pupil size, and basal tear secretion were unchanged in both groups. Burning upon instillation of the drops was more frequent with betaxolol.

Comparative aqueous outflow facility measurements by pneumatonography and Schiotz tonography

Tonography was performed on 36 eyes of 15 normal and 3 primary open angle glaucoma patients using pneumatonography and classical Schiotz tonography. The average values of the coefficient of outflow facility (C) for the whole sample were virtually identical with both methods. However, both intersubject and interobserver variability were significantly higher with penumatonography. Although both methods provide comparable aggregate estimates of aqueous outflow facility, we think that Schiotz tonography is more reliable than pneumatonography because of the greater mechanical stability of the Schiotz instrument on the eye. On the other hand, pneumatonography offers the advantage of a shorter test period (2 min instead of 4).

Decreased intraocular pressure in the hypertensive human eye with betaxolol, a beta 1-adrenergic antagonist

In a double-masked randomized prospective study, 19 adult white subjects with primary open-angle glaucoma or ocular hypertension were treated twice daily with drops of 0.25% betaxolol (a relatively selective beta 1-adenoceptor antagonist) or placebo for six weeks. The nine betaxolol-treated subjects demonstrated a statistically significant average decrease in intraocular pressure of 3.8 +/- 5 mm Hg, evident after one week and persisting throughout the entire six-week treatment period. The ten placebo-treated subjects exhibited a statistically nonsignificant increase in intraocular pressure of 0.4 +/- 2.4 mm Hg. Mean systemic arterial blood pressure, pulse rate, corneal sensitivity, pupil diameter, and basal tear secretion remained unchanged in both groups. Transient stinging upon instillation of the eyedrops was the only side effect in the betaxolol-treated subjects but in no case did it necessitate cessation of therapy.

Is the endolymphatic sac always accessible?

All surgical manipulations of the endolymphatic sac have a common requirement: to identify the intradural part. We studied the position of the intradural endolymphatic sac in relation to the posterior semicircular canal, the sigmoid sinus, the retrofacial air cell tract, and the jugular bulb in 50 temporal bones. The intradural sac was identifiable in 48 cases; in two the sac either was absent or would not have been identifiable surgically without jeopardizing other important structures, particularly the posterior semicircular canal.

A transsternal approach to the upper thoracic vertebrae

An anterior surgical approach to the upper thoracic vertebrae has been described. A T-shaped skin incision is used, with the horizontal limb 1 cm above the clavicle, and the vertical limb extending in the midline over the body of the sternum. A portion of the manubrium sterni, as well as the medial third of the clavicle, is resected; the avacular tissue plane between the carotid sheath laterally and the trachea and esophagus medially is developed to reach the prevertebral space. After surgery, immediate fusion is performed using the clavicle and manubrium. This procedure is well tolerated, and was associated with minimal morbidity and no mortality in a series of seven patients.

Endolymphatic sac: possible role in autoimmune sensorineural hearing loss

Histologic examination of the temporal bone of a patient with Wegener's granulomatosis showed involvement of the vessels of the endolymphatic sac (ELS) but no involvement of the vasculature of the rest of the inner ear. Autoimmune sensorineural hearing loss in this patient may have been due to interference of antigens and antibodies with the filtering capacity of the ELS, leading to imbalance of inner ear fluids. Histologic findings reemphasize that the cochlea and ELS have different blood supplies.