Studies of MEMS Acoustic Sensors as Implantable Microphones for Totally Implantable Hearing-Aid Systems

There is a need for high-quality implantable microphones for existing semiimplantable middle-ear hearing systems and cochlear prosthesis to make them totally implantable, thus overcoming discomfort, inconvenience, and social stigma. This paper summarizes and compares the results of an in-vitro study on three design approaches and the feasibility of using microelectromechanical system acoustic sensors as implantable microphones to convert the umbo vibration directly into a high-quality sound signal. The requirements of sensors were selected including the ability to withstand large body shocks or sudden changes of air pressure. Umbo vibration characteristics were extracted from literature and laboratory measurement data. A piezoelectric vibration source was built and calibrated to simulate the umbo vibration. Two laboratory models of the acoustic sensor were studied. The model-A device, using electrets-microphone as the sensor, was designed and tested in the laboratory and on temporal bones. The results verify that the laboratory measurement is consistent with the temporal bone characterization and achieves a near flat frequency response with a minimum detectable signal of a 65-dB sound-pressure-level (SPL) at 1 kHz. The model-B sensor was then designed to increase the sensitivity and provide an easy mounting on umbo. The model-B device can detect 40-dB SPL sound in the 1-2 kHz region, with 100-Hz channel bandwidth. The results of model-A and model-B displacement sensors and the acceleration sensor are summarized and compared. A preliminary design of the implantable displacement sensor for totally implantable hearing-aid systems is also presented.

Diagnosis and management of spontaneous cerebrospinal fluid-middle ear effusion and otorrhea

OBJECTIVES/HYPOTHESIS

Spontaneous leak of cerebrospinal fluid (CSF) into the middle ear can occur in adults without a history of temporal bone trauma or fracture, meningitis, or any obvious cause. Therefore, clues may be lacking that would alert the otolaryngologist that fluid medial to an intact eardrum, or fluid emanating from an eardrum perforation, is likely to be CSF fluid. A review of relevant medical literature reveals that herniation of the arachnoid membrane through a tegmen defect may be congenital, or CSF leak may occur when dynamic factors (i.e., brain pulsations or increases in intracranial pressure) produce a rent in the arachnoid membrane. Because tegmen defects may be multiple rather than single, identifying only one defect may not be sufficient for achieving definitive repair. Data on nine cases of spontaneous CSF leak to the ear in adult patients from four medical centers are presented and analyzed to provide collective information about a disorder that can be difficult to diagnose and manage.

STUDY DESIGN

Retrospective review of nine cases of spontaneous CSF middle ear effusion/otorrhea.

RESULTS

The majority of patients presented with symptoms of aural fullness and middle ear effusion. Many developed suspicious clear otorrhea only after insertion of a tympanostomy tube. Two patients had multiple defects in the tegmen and dura, and five patients had meningoencephaloceles confirmed intraoperatively. Five patients underwent combined middle cranial fossa/transmastoid repair. Materials used in repair included temporalis fascia, free muscle graft, Oxycel cotton, calvarial bone, pericranium, bone wax, and fibrin glue.

CONCLUSIONS

CSF middle ear effusion/otorrhea can develop in adults without a prior history of meningitis or head trauma or any apparent proximate cause. Although presenting symptoms can be subtle, early suspicion and confirmatory imaging aid in establishing the diagnosis. Because surgical repair by way of a mastoid approach alone can be inadequate if there are multiple tegmen defects, a middle fossa approach alone, or in combination with a transmastoid approach, should be considered in most cases.

Hearing Rehabilitation Using the BAHA Bone-Anchored Hearing Aid: Results in 40 Patients

OBJECTIVE

This study evaluates the U.S. experience with the first 40 patients who have undergone audiologic rehabilitation using the BAHA bone-anchored hearing aid.

STUDY DESIGN

This study is a multicenter, nonblinded, retrospective case series.

SETTING

Twelve tertiary referral medical centers in the United States.

PATIENTS

Eligibility for BAHA implantation included patients with a hearing loss and an inability to tolerate a conventional hearing aid, with bone-conduction pure tone average levels at 60 dB or less at 0.5, 1, 2, and 4 kHz.

INTERVENTION

Patients who met audiologic and clinical criteria were implanted with the Bone-Anchored Hearing Aid (BAHA, Entific Corp., Gothenburg, Sweden).

MAIN OUTCOME MEASURES

Preoperative air- and bone-conduction thresholds and air-bone gap; postoperative BAHA-aided thresholds; hearing improvement as a result of implantation; implantation complications; and patient satisfaction.

RESULTS

The most common indications for implantation included chronic otitis media or draining ears (18 patients) and external auditory canal stenosis or aural atresia (7 patients). Overall, each patient had an average improvement of 32+/-19 dB with the use of the BAHA. Closure of the air-bone gap to within 10 dB of the preoperative bone-conduction thresholds (postoperative BAHA-aided threshold vs. preoperative bone-conduction threshold) occurred in 32 patients (80%), whereas closure to within 5 dB occurred in 24 patients (60%). Twelve patients (30%) demonstrated 'overclosure' of the preoperative bone-conduction threshold of the better hearing ear. Complications were limited to local infection and inflammation at the implant site in three patients, and failure to osseointegrate in one patient. Patient response to the implant was uniformly satisfactory. Only one patient reported dissatisfaction with the device.

CONCLUSIONS

The BAHA bone-anchored hearing aid provides a reliable and predictable adjunct for auditory rehabilitation in appropriately selected patients, offering a means of dramatically improving hearing thresholds in patients with conductive or mixed hearing loss who are otherwise unable to benefit from traditional hearing aids.

Outpatient tympanomastoidectomy: factors affecting hospital admission

BACKGROUND

Outpatient tympanomastoidectomy is common in many medical centers. However, failure of same-day discharge is often the result of postoperative nausea and vomiting (PONV). Many times this leads to hospital admission after tympanomastoidectomy, and it is often difficult to predict before surgery whether PONV will be an issue that impedes same-day discharge.

OBJECTIVE

To determine the clinical factors correlated with the incidence of PONV requiring hospital admission after chronic ear surgery by hypothesizing that the complexity of a particular case, as measured using a 10-point scale, is predictive of surgical time or failure of same-day hospital discharge.

STUDY DESIGN

Retrospective medical chart review of 103 patients having mastoidectomy with tympanoplasty for chronic otitis media over a 2-year period.

METHODS

We recorded patient age, clinical data, surgical times, types of agents used for induction and maintenance of anesthesia, use of prophylactic antiemetic drugs, types and doses of analgesic agents, and PONV. Univariate and multivariate logistic regression analyses were performed to determine which variables were associated with PONV that required hospital admission.

RESULTS

One third of patients studied were safely discharged from the hospital the day of surgery, and 92% were discharged within 23 hours. The most common cause for observation admission to the hospital was PONV. The only variable in multivariate analysis that significantly correlated with PONV mandating hospital admission after tympanomastoid surgery was a history of motion sickness or PONV (odds ratio, 5.21; P =.02). Although severity of disease did not correlate with length of hospital stay, it directly correlated with length of surgery.

CONCLUSIONS

A history of PONV or motion sickness is predictive of PONV and length of hospital stay. Routine planning for a 23-hour overnight observation stay seems warranted for all patients undergoing tympanomastoidectomy, despite severity of disease.

Patients' perceived outcomes after stapedectomy for otosclerosis

We conducted a retrospective study of 29 patients who had undergone stapedectomy for otosclerosis to determine how well their subjective perceptions of hearing improvement correlated with objective audiometric measurements. Patients expressed their assessments of hearing function by completing two versions of the Hearing Disability and Handicap Scale (HDHS). One version of the HDHS was based on patients' retrospective recollections of their hearing impairment prior to surgery, and the other reflected their assessment of their current function. We evaluated these HDHS data both separately and in conjunction with pre- and postoperative audiometric findings. Following surgery, the group's mean pure-tone average improved significantly, from 58 to 27 dB--that is, the average patient had a moderately severe hearing loss preoperatively and only a mild hearing loss postoperatively. Significant improvement was also reflected in the difference between the mean pre- and postoperative HDHS scores, although some patients indicated that they experienced almost no improvement. Overall, our findings indicated that there was a relationship between objective and subjective assessments of hearing improvement following surgery, but that it was weak. Although most patients perceived significant improvement, the degree of that perceived improvement cannot be predicted from the pure-tone audiogram. We conclude, therefore, that a significant difference between audiometric findings and HDHS self-assessments is useful in identifying patients who might benefit from additional counseling and/or aural rehabilitation.

Spondyloepiphyseal dysplasia congenita associated with conductive hearing loss

Spondyloepiphyseal dysplasia is a disorder characterized by abnormalities of growth. Previous studies of this disorder have identified a significant incidence of associated hearing loss. Hearing loss has been reported to occur in 25 to 30% of affected patients. To date, all reports of associated hearing loss have indicated the presence of a sensorineural component. In this article, we report the case of a child who was diagnosed with spondyloepiphyseal dysplasia congenita and who was found to have a significant conductive hearing loss with a Carhart's notch, indicating the likely presence of stapes footplate fixation. We also review the diagnosis of this condition and the literature associated with hearing loss as it occurs with this disorder.

Minimally invasive technique of auricular cartilage harvest for tissue engineering

Tissue engineered human cartilage is presently being utilized in clinical research programs in a variety of medical disciplines including otolaryngology, urology, and orthopedics. In this study, we present a new methodology for auricular cartilage harvest that can be applied to tissue engineering. Eight 16-week-old pigs were subjected to a traditional open cartilage harvest technique involving suture closure, while the other ear was subjected to the closed stitchless cartilage harvest, using a 12-gauge core biopsy needle. Surgical time was significantly (p < 0.0001) shorter (3.5 +/- 2.8 min for closed vs. 14.4 +/- 5 min for open), and no sutures where utilized in the closed technique. Sample weights were significantly (p < 0.00001) greater (0.115 +/- 0.028 g vs. 0.045 +/- 0.005 g) for the closed techniques. However, the minimally invasive closed technique had fewer incidents of bruising, hematoma, long-term stitch abscess, and scarring. Cell culture data shows no disadvantage to either technique with regards to cell growth characteristics. Final histological data from donor ears indicates favorable results with the minimally invasive technique. This technique preserves cell viability and isolation efficiency while decreasing surgical time and lessening postoperative complications.

Temporal bone fractures: otic capsule sparing versus otic capsule violating clinical and radiographic considerations

OBJECTIVE

To assess the practicality and utility of the traditional classification system for temporal bone fracture (transverse vs. longitudinal) in the modern Level I trauma setting and to determine whether a newer system of designation (otic capsule sparing vs. otic capsule violating fracture) is practical from a clinical and radiographic standpoint.

METHODS

The University of Massachusetts Medical Center Trauma Registry was reviewed for the years 1995 to 1997. Patients identified as sustaining closed head injury were reviewed for basilar skull fracture and temporal bone fracture. Clinical and radiographic records were evaluated by using the two classification schemes.

RESULTS

A total of 2,977 patients were treated at the trauma center during this time. Ninety (3%) patients sustained a temporal bone fracture. The classic characterization of transverse versus longitudinal fracture (20% vs. 80%, respectively) was unable to be determined in this group; therefore, clinical correlation to complications using that paradigm was not possible. By using the otic capsule violating versus sparing designation, an important difference in clinical sequelae and intracranial complications became apparent. Compared with otic capsule sparing fractures, patients with otic capsule violating fractures were approximately two times more likely to develop facial paralysis, four times more likely to develop CSF leak, and seven times more likely to experience profound hearing loss, as well as more likely to sustain intracranial complications including epidural hematoma and subarachnoid hemorrhage.

CONCLUSION

The use of a classification system for temporal bone fractures that emphasizes violation or lack of violation of the otic capsule seems to offer the advantage of radiographic utility and stratification of clinical severity, including severity of Glasgow Coma Scale scores and intracranial complications such as subarachnoid hemorrhage and epidural hematoma.

Facial canal decompression leads to recovery of combined facial nerve paresis and trigeminal sensory neuropathy: case report

BACKGROUND

Trigeminal sensory neuropathy is often associated with facial idiopathic nerve paralysis (Bell's palsy). Although a cranial nerve viral polyneuropathy has been proposed as the usual cause, in many instances the etiology remains unclear. This case report of recovery of both trigeminal and facial neuropathy after surgical decompression of the facial nerve suggests an anatomic link.

METHODS

A case of a 39-year-old woman presenting with recurrent unilateral facial paralysis is summarized. Her fifth episode, which did not spontaneously recover, was associated with retroorbital and maxillary pain as well as sensory loss in the trigeminal distribution.

RESULTS

A middle cranial fossa approach for decompression of the lateral internal auditory canal, labyrinthine segment of the facial nerve and the geniculate ganglion was performed. The patient's pain and numbness resolved immediately postoperatively, and the facial paralysis improved markedly.

CONCLUSION

This result implicates a trigeminal-facial reflex as hypothesized by others. It suggests that decompression of the facial nerve can lead to improvement in motor and sensory function as well as relief of pain in some patients with combined trigeminal and facial nerve dysfunction.

Merkel cell carcinoma of the external auditory canal invading the intracranial compartment

PURPOSE

To report an unusual case of an intracranial extension of Merkel cell carcinoma originating in the external ear canal and causing neurological deficits.

CASE REPORT

An 86-year-old woman, with a 16-month history of an external auditory canal mass, presented with hemiparesis, facial paralysis, and obtundation. Radiographic images showed an intracranial mass extending into the petrous bone.

METHOD

The patient had a craniotomy for intracranial tumor resection with concurrent mastoidectomy for facial nerve decompression and obtundation and hemiparesis were resolved. Residual tumor was subsequently treated with adjuvant radiation therapy, and facial nerve function consequently improved.

CONCLUSION

Merkel cell tumors rarely invade the intracranial compartments. Residual tumor and neurological deficits may respond to adjuvant radiation therapy.

Improved axon diameter and myelin sheath thickness in facial nerve cable grafts wrapped in temporoparietal fascial flaps

Injury to the facial nerve in the temporal bone presents a challenge to the recovery of nerve function, in that the fallopian canal in which it lies is poorly vascularized. This study was designed to determine if wrapping an intratemporal facial nerve defect repaired with a cable graft with a well-vascularized temporoparietal fascial (TPF) flap would improve facial nerve regeneration. To evaluate this question, a defect was created in the intratemporal left facial nerve of 10 rabbits. All nerves were repaired using cable grafts. In 5 animals, the nerve graft was wrapped with temporoparietal fascia, whereas in the other 5 rabbits it was not. Three additional animals underwent exposure only. The contralateral nerve served as a control in all animals. Quantitative analysis of the nerve graft 12 weeks after repair revealed greater recovery of original fiber diameter and myelin sheath thickness in TPF flap-wrapped repairs. Histological evidence of improved neural regeneration and functional nerve recovery was also seen in the repairs where the TPF flap was utilized. Nerve conduction and electromyographic studies of the cable-grafted nerve at 6 and 12 weeks were equivocal, however.

Hemangioma of the Middle Ear

An 80-year-old woman was referred to the Massachusetts Eye and Ear Infirmary by her primary care physician for evaluation of a red mass behind her right tympanic membrane. The patient gave a history of a long-standing, stable, right-sided hearing loss and denied all other aural symptoms, including tinnitus, vertigo, otorrhea, and otalgia. Her past otolaryngologic history was significant for a transcanal excision of a hemangioma originating in the right epitympanum in 1953.

Trigeminal neo-neurotization of the paralyzed face

Sporadic reports throughout the literature have documented the spontaneous return of facial function following deliberate intraoperative sacrifice of the facial nerve. Trigeminal reinnervation of the facial muscles has been suggested as one possible mechanism for this occurrence. Evidence for the phenomenon of trigeminal neo-neurotization has been documented experimentally. The case of a 62-year-old woman who underwent total left parotidectomy with transection of a large facial nerve segment is presented in order to provide further clinical evidence supporting trigeminal neo-neurotization of the facial nerve. Despite the lack of any efforts to reinnervate the patient or graft the facial nerve defect, the patient spontaneously developed return of facial function. Postoperative clinical and electrical testing in this case supports trigeminal-facial reinnervation as the cause for return of facial function. The case report is summarized with a brief discussion, and the relevant literature is thoroughly reviewed.

Invisible culprit: intralabyrinthine schwannomas that do not appear on enhanced magnetic resonance imaging

Intralabyrinthine schwannoma (ILS) is an infrequent tumor that arises in isolation within the periphery of the temporal bone. Only 32 cases have been reported to date in the literature, of which 12 were discovered at autopsy. Prior to the advent of gadolinium-enhanced magnetic resonance imaging (Gd-MRI), only 1 ILS had been diagnosed preoperatively. However, after Gd-MRI became a common modality, 5 ILSs were imaged. Two additional cases are reported that were discovered during labyrinth-destructive surgery despite normal Gd-MRI findings. Possible explanations for and potential ramifications of nonenhancing ILS are discussed.

Ganglionic hamartoma of the intracanalicular acoustic nerve causing sensorineural hearing loss

OBJECTIVE

This article highlights the clinical presentation and treatment issues of ganglionic hamartoma of the internal auditory canal and emphasizes the similarity of this lesion to acoustic neuroma regarding its audiologic and radiographic characteristics.

STUDY DESIGN

This article is composed of case reports and a literature review.

SETTING

The study was performed at a university hospital/tertiary referral center.

PATIENT

A patient with biopsy-proven ganglionic hamartoma of the acoustic nerve was studied.

INTERVENTION

Intervention consisted of surgical therapy.

MAIN OUTCOME MEASURE

The main outcome measure was clinical evaluation.

RESULTS

The result was successful removal of lesions with facial nerve preservation.

CONCLUSIONS

An intracanalicular ganglionic hamartoma resulted in progressive sensorineural hearing loss and magnetic resonance imaging findings suggestive of small acoustic neuroma. This lesion, composed of an admixture of ganglion cells, fibroadipose-tissue, and normal myelinated axons, although rare, should be added to the differential diagnosis of internal auditory canal lesions.

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.

Differential expression of transthyretin in papillary tumors of the endolymphatic sac and choroid plexus

Aggressive papillary tumors of the temporal bone, occurring sporadically or as part of von Hippel-Lindau disease, have been shown to originate within the endolymphatic sac or duct. Also implicated as a potential precursor from which some of these tumors may arise is ectopic choroid plexus epithelium. To aid in the differentiation between papillary tumors of endolymphatic sac and duct origin and those arising from choroid plexus, an immunohistochemical study using stains for transthyretin (TTR), cytokeratins, S-100 protein, epithelial membrane antigen (EMA), and glial fibrillary acidic protein (GFAP) was carried out on archival specimens of normal and neoplastic endolymphatic sac and duct and choroid plexus epithelium. Transthyretin, a marker for choroid plexus epithelium, was found to show differential expression between choroid plexus papillomas and aggressive papillary tumors of the endolymphatic sac or duct. Therefore the use of TTR in concert with other immunohistochemical stains appear to aid in the differentiation between intracranial and intratemporal papillary tumors arising from choroid plexus and endolymphatic sac or duct epithelium.

The subtemporal-transpetrous approach for excision of petroclival tumors

The subtemporal transpetrous approach to the petroclival region uses a combination of techniques, including a petrosectomy and a subtemporal and suboccipital craniotomy. Ligation of the greater petrosal sinus, sigmoid sinus, and retraction of the temporal lobe affords wide exposure to the petroclival region and ventral brainstem and minimizes the need for facial nerve translocation. This approach has been successfully used in the management of 10 large tumors of the region, including chondrosarcomas, chordomas, meningiomas, and schwannomas. The history and evolution of this technique and its relation to other similar approaches is discussed.

A method for determining interaural attenuation in animal models of asymmetric hearing loss

Asymmetric or unilateral sensorineural hearing loss is an important hall-mark of various forms of sensorineural hearing loss. Animal research regarding the etiology and mechanism of these disorders often requires hearing estimates in each ear of experimental animals. Monaural auditory testing of animals with experimentally induced unilateral hearing loss therefore requires prior knowledge of interaural attenuation (IAA) to facilitate contralateral masking. The purpose of this study is to describe a method of determining frequency-specific IAA data and to present relevant information obtained in the rats--a frequently used animal in studies of acquired sensorineural hearing loss. A custom-made sound source was designed to accomplish threshold determination at important frequencies in the dynamic range of rats. Six male Long-Evans rats were surgically monauralized by ablation/obliteration of the cochlea. Auditory brainstem response (ABR) thresholds were determined for ipsilateral and contralateral presentations of 2-kHz, 10-kHz, and 40-kHz toneburst. IAA was calculated by subtracting the frequency-specific ABR threshold obtained from the normal ear from that obtained following tone presentation to the 'dead' ear, and was found to average 65.0 +/- 10.5 dB at 2 kHz, 45.0 +/- 8.4 dB at 10 kHz, and 47 +/- 15.1 dB at 40 kHz (+/- standard deviation). Using data obtained from the animal demonstrating the smallest IAA, masking is not needed until a threshold asymmetry of 50 dB at 2 kHz and 30 dB at 10 and 40 kHz is observed. In order to obtain bilateral auditory threshold information in any animal model of asymmetric hearing loss, data regarding IAA are needed in order to know when to apply contralateral masking and therefore avoid crossover stimulation of the non-test ear. The protocol presented herein provides guidelines for use in any animal model of sensorineural hearing loss which may demonstrate unilateral or asymmetric deficits.

Delayed facial paralysis after acoustic neuroma surgery: factors influencing recovery

Patients with satisfactory facial nerve function [House-Brackmann (HB) grade I or II] immediately after acoustic neuroma surgery are at risk for delayed facial paralysis. To study this problem, 255 consecutive patients who underwent acoustic neuroma excision with facial nerve preservation were identified. Delayed facial paralysis occurred in 62 (24.3%) patients; 90% ultimately recovered to their initial postoperative HB grade, and 98.3% recovered to within one grade of their initial HB level. Paralysis occurred at an average of 3.65 postoperative days (range, 1-16 days). The average time to maximal recovery for those with changes of 1, 2, 3, and 4 HB grades was 5.6, 21.5, 39.8, and 50.5 weeks, respectively. The early onset of paralysis (< 48 h after surgery) resulted in shorter average recovery times. Of patients who demonstrated nerve deterioration to grades IV-VI, 20 of 38 required tarsorrhaphy or gold-weight placement. We conclude that the over-whelming majority of patients with delayed facial paralysis after acoustic neuroma surgery do eventually recover to their postoperative HB grade. The magnitude and timecourse of delayed facial paralysis are predictive factors for subsequent recovery.

The use of the temporoparietal fascial flap in temporal bone reconstruction

After routine canal wall down mastoidectomy, local muscle flaps with and without bone paté, cartilage and fascia are the standard techniques available to otologists wishing to obliterate the mastoid and reconstruct the external auditory canal. Reconstructive options for temporal bone defects after extirpative surgery for cancer, osteoradionecrosis, and revision surgery for chronic granulomatous otitis media, however, are few. Although the neighboring temporoparietal fascia flap (TPFF), based on the superficial temporal vessels, has been frequently employed for auricular reconstruction, its versatility in temporal bone reconstruction has not been widely explored. The TPFF has recently been employed at our institution in 11 patients who presented with a variety of reconstructive problems, including defects after temporal bone resection, surgery for malignant otitis externa, and revision mastoid surgery. Follow-up in these patients ranged from 1 to 43 months (average 18.4 months) and surgical objectives of achieving a dry mastoid bowl, fully epithelialized canal, and/or reduction of mastoid cavity volume was attained in 100% of cases. The TPFF offers many advantages to the otologic surgeon when faced with reconstruction dilemmas that center around a poorly vascularized mastoid cavity and temporal bone. The TPFF is a reliable source of local well-vascularized tissue that is extremely pliable and facilitates both hearing and nonhearing preservation temporal bone reconstruction.

Teflon granuloma presenting as an enlarging, gadolinium enhancing, posterior fossa mass with progressive hearing loss following microvascular decompression

Deleterious effects of Teflon strand placement during microvascular decompression (MVD) for hemifacial spasm are rare. In this report, a patient who had previously undergone suboccipital MVD for hemifacial spasm presented 3 years postoperatively with a progressive asymmetric sensorineural hearing loss and magnetic resonance imaging evidence of an enlarging ipsilateral gadolinium enhancing 1-cm cerebellopontine angle lesion. At surgery a granuloma was found displacing the structures of the internal auditory canal. Histologically, evidence of a Teflon fiber-induced giant cell granuloma was identified. This paper reviews the literature of Teflon-induced histopathology as it relates to posterior fossa MVD surgery, as well as its relation to this previously unreported complication.

Early temporalis muscle transposition for the management of facial paralysis

Temporalis muscle transposition is a reliable surgical technique for the reanimation of patients with long-standing facial paralysis. It is often employed when facial nerve reinnervation via crossover or cable grafting is not possible. Temporalis muscle transposition can also be used for the immediate treatment of complete facial paralysis due to insults leaving the facial nerve anatomically intact but requiring a prolonged recovery time (more than 1 year). Because temporalis muscle transposition does not interfere with neuronal regeneration, it may be employed early in the management of complete facial paralysis when recovery is predicted to be extended and incomplete. The authors report their experience with early temporalis muscle transposition in the management of facial paralysis in 56 patients with an anatomically intact facial nerve. More than 90% of these patients achieved improved symmetry at rest as well as purposeful movement at the corner of the mouth. In the last 30 patients, the temporoparietal fascial flap was simultaneously harvested and successfully used to obliterate the donor site defect. In conjunction with the immediate implantation of a gold weight in the ipsilateral upper eyelid, this approach to the early management of facial paralysis helps reduce the period of facial disability from years to weeks in a select group of patients.

Endolymphatic sac tumors: histopathologic confirmation, clinical characterization, and implication in von Hippel-Lindau disease

The term "endolymphatic sac tumor" (ELST) was coined to identify the likely origin of aggressive papillary tumors of the temporal bone. To evaluate the validity of this designation, the temporal bone collection at the Massachusetts Eye and Ear Infirmary was accessed in an effort to determine the pathologic relationship between these tumors and the endolymphatic sac. The search resulted in the identification of a de-novo papillary epithelial lesion arising within the confines of the endolymphatic sac in a patient with von Hippel-Lindau (VHL) disease who harbored a large, destructive ELST in the opposite temporal bone. This finding provides the most substantial evidence to date regarding the origin of the ELST and the accuracy of its nomenclature. Seven additional clinical cases of ELST were identified and analyzed in order to define the natural history of these tumors. All patients had a history of sensorineural hearing loss diagnosed an average of 10.6 years prior to tumor discovery. The presence of a polypoid external auditory canal mass, facial paralysis, and evidence of a destructive mass arising on the posterior fossa surface of the temporal bone were common physical and radiographic findings. The management of these patients, as well as those who are probably prone to such tumors (i.e., VHL patients), is discussed.

Fibrous dysplasia of the temporal bone: ten new cases demonstrating the spectrum of otologic sequelae

monostotic. Although most patients had a conductive hearing loss, 17% of patients demonstrated profound sensorineural hearing loss ascribable to the lesion, and facial nerve sequelae were noted in nearly 10% of cases. Cholesteatoma complicated almost 40% of cases, usually in the form of a canal cholesteatoma. Ten new cases of temporal bone fibrous dysplasia are described not only to further clarify the spectrum of otologic sequelae but also to help illustrate available treatment options. In addition, this report documents, in three new cases, the previously undescribed progression of conductive hearing loss to profound sensorineural deafness secondary to fibrous dysplasia.

Metoclopramide enhances the effect of photodynamic therapy on xenografted human squamous cell carcinoma of the head and neck

OBJECTIVE

Photodynamic therapy (PDT) is a promising new treatment modality for head and neck cancer that is based on the uptake of a systemically administered photosensitizer in tumor tissue and local illumination of the lesion by a high-intensity visible light source, typically a tunable argon-pumped dye laser. We developed a new photosensitizer named silicon phthalocyanine [SiPc(OH) OSi(CH3)2(CH2)3N(CH3)2, abbreviated as SiPc IV], which yields superior PDT responses in vitro and in vivo compared with other clinically used photosensitizers. However, tumor regrowth following SiPc IV-based PDT is still a therapeutic problem. The benzamide derivatives, for example, have been shown to enhance tumor ablation when used during radiotherapy and chemotherapy. Therefore, we used metoclopramide hydrochloride, a benzamide derivative, to evaluate its effects on PDT response.

DESIGN

Intradermally injected human squamous cell carcinoma cells were grown to 40 to 80 mm3 in athymic nude mice and irradiated with 675-nm light (75 J/cm2, 75 mW/cm2) 24 hours after the intraperitoneal injection of SiPc IV (1.0 mg/kg). Metoclopramide hydrochloride (2 to 48 mg/kg) was injected intraperitoneally 1 hour before and 24 and 48 hours after irradiation.

RESULTS

Tumors exposed to PDT alone showed 80% to 90% tumor regression with regrowth in most animals within 20 days. Tumors treated with metoclopramide hydrochloride (48 mg/kg) plus PDT demonstrated 100% tumor regression without regrowth up to the time of killing (150 days). No observable toxic effects were clinically apparent with the high doses of metoclopramide.

CONCLUSIONS

Our results show that administering metoclopramide in combination with PDT may be a promising approach to the management of head and neck cancer.

Fibrous dysplasia of the temporal bone: imaging findings

Lichtenstein [1] in 1938 coined the term fibrous dysplasia to describe a disorder characterized by the progressive replacement of normal bone elements by fibrous tissue. Histopathologically, these lesions consist of an abnormal proliferation of fibrous elements intermixed with haphazardly arranged trabeculae of woven bone. The disease can involve any bone in the body. In the head and neck, the skull and facial bones are involved in 10-25% of cases of monostotic fibrous dysplasia and in 50% of the polyostotic variety. Involvement of the temporal bone, however, is relatively rare, and only 53 cases have been reported. The three major radiographic classifications of fibrous dysplasia are pagetoid, sclerotic, and cystic. Any of these types may involve the temporal bone and related structures, including the external canal, middle ear, jugular foramen, or, rarely, the otic capsule. In this essay, we illustrate the radiographic features of the disease based on our experience with seven cases, seen at our institution since 1977, of fibrous dysplasia involving the temporal bone.

Non-paraganglioma jugular foramen lesions masquerading as glomus jugulare tumors

Pulsatile tinnitus, hearing loss, lower cranial nerve deficits, and radiographic evidence of a vascular lesion of the jugular foramen have been considered diagnostic of a glomus jugulare tumor. Angiographic evidence of a blood supply from the external carotid artery system, including the ascending pharyngeal artery, further substantiates this diagnosis. This diagnostic algorithm for tumors of the jugular fossa is usually followed by either a surgical exenteration of a presumed glomus jugulare tumor via an infratemporal fossa approach or radiation therapy in selected patients. Pre-treatment biopsy of such lesions is typically not done, nor is it recommended widely in the literature. As demonstrated in this report, a number of lesions, including hemangiopericytoma and extramedullary plasmacytoma presenting in the jugular foramen can mimic glomus jugulare tumors in all aspects of their clinical and radiographic presentation. Omission of a pre-treatment biopsy can lead to a treatment plan appropriate for glomus tumors but suboptimal for these rare pathologic entities. A pre-treatment biopsy of lesions of the jugular foramen by exploratory tympanotomy or postauricular mastoidotomy provides a pathologic diagnosis on which to base treatment of lesions of the jugular foramen, without adding substantial morbidity or decreasing the chances of cure.

Parotidectomy: a ten year experience with fine needle aspiration and frozen section biopsy correlation

During the years 1980 through 1990, 247 patients underwent parotidectomy at our institution for the removal of primary parotid lesions. Charts were reviewed in an effort to document the distribution of pathology in patients undergoing parotidectomy and the histopathology from each case was organized and tallied by virtue of the final specific diagnoses. An additional goal of this study was to evaluate the efficacy of pre-operative fine-needle aspiration biopsy (FNAB) and frozen section pathology in accurately predicting final histopathology. In our series, 86.7% of lesions were found to be benign and 13.3% were malignant in nature. When compared to final pathologic findings, FNAB yielded a diagnostic accuracy rate of 89.3% with a 2.1% false negative rate with regards to pre-operative detection of malignancy. Frozen section biopsy was found to have a diagnostic accuracy of 94.1% and also demonstrated a 2.1% false-negative rate. We believe these studies are indeed complementary to each other, as reflected in the 96.2% diagnostic accuracy achieved with a combination of FNAB and frozen section biopsy information. This report will review the patterns of misdiagnosis for each modality of diagnostic testing and present the parotid histopathology found over a 10-year period.

Photodynamic therapy of human squamous cell carcinoma in vitro and in xenografts in nude mice

Photodynamic therapy (PDT) of cancer is an experimental tumor therapy which is based on the combined use of a systematically administered photosensitizer to a tumor-bearing host and local illumination of the lesion by a high-intensity visible light source, typically a tunable argon dye laser. Human squamous cell carcinoma (HSCC) is the most frequently encountered malignancy of the head and neck. In this study, responses of HSCC cells to PDT were examined in in vitro and in vivo systems. In in vitro studies, the HSCC cells showed a positive photodynamic response with Photofrin-II (Pf-II), chloroaluminum phthalocyanine tetrasulfonate (AlPcTS), and a newly synthesized silicon phthalocyanine (SiPc IV). Single cell suspension of HSCC injected subcutaneously on the back of athymic nude mice resulted in a well-circumscribed tumor mass. The animals required a low tumor dose for the successful establishment of a tumor. The tumor was minimally immunogenic and showed neither macroscopic signs of early metastasis to lung, kidney, liver, or spleen nor evidence of surrounding erythema, fluctuation, or tenderness until the late stages of necrosis. Intraperitoneal administration of AlPcTS or SiPc IV to tumor-bearing mice resulted in rapid uptake of the photosensitizers in liver, skin, and tumor tissue. Twenty-four hours following the intraperitoneal administration of AlPcTS or SiPc IV to tumor-bearing animals, the tumor to normal skin ratio of the photosensitizer was 1.6 or 1.5, respectively. Administration of Pf-II (5 mg/kg) to tumor-bearing animals followed 24 hours later by irradiation of the tumor (135 J/cm2, 630 nm light from an argon pumped-dye laser) resulted in greater than 80% ablation in tumor volume 24 hours post-PDT. These characteristics make this tumor model system suitable for PDT studies of human tumor cells in vitro as well as in vivo.

Pulmonary sequelae of intraparenchymal bismuth subgallate

Bismuth subgallate (BSG) is a heavy metal compound which is effective in lowering the incidence of hemorrhage after adenotonsillectomy and has been demonstrated to activate Factor XII. In a minority of children, the paste has been suctioned from the cuffless oral endotracheal tube after adenotonsillectomy. No pulmonary sequelae have been noted in these patients. To assess the effect of BSG aspiration, 75 rats were divided into groups receiving either intratracheal BSG or saline. Early and late parenchymal effects were documented at 5 and 30 days following administration. Although there were no differences in the general well-being, activity level, or weight in these rats, acute pneumonia followed by a histiocytic, foreign-body response was noted in a significant number of rats in the BSG group. Although no clinical pulmonary sequelae of BSG use have been noted in our patients, this information should alert clinicians to the risks of BSG use in the pulmonary-compromised patient, and encourage them to either employ all methods of preventing aspiration in such patients when using BSG, or to use another hemostatic modality for the utmost safety.

Inferior mastoidectomy-hypotympanic approach for surgical removal of glomus jugulare tumors: an anatomical and radiologic study emphasizing distances between critical structures

The technique of inferior mastoidectomy-hypotympanic dissection, with preservation of the middle and inner ear structures, has been established for radical surgical removal of glomus tumors involving the skull base. In order to study the gross anatomic differences and correlate with the computed tomography (CT) scan, 20 human temporal bones were dissected and accurate measurements between vital structures were made. This study revealed a wide variation in distances between the neurovascular structures, whereas the distances between inner ear structures were not statistically different. This original study of critical distances of gross topographic anatomical structures and CT correlation is very helpful indeed in the understanding of variations found in the surgical removal of lesions involving this important and challenging area of the skull base. The inferior mastoidectomy-hypotympanic dissection has been performed in the removal of six suitable tumors involving the jugular bulb area. This technique, combined with upper cervical dissection, is very useful for the radical removal of such neoplasms with preservation of external and middle ear structures as well as the function of the facial, eighth, and other lower cranial nerves.

Angioedema: 5 years' experience, with a review of the disorder's presentation and treatment

Angioedema is a problem that the otolaryngologist-head and neck surgeon is often asked to treat. This report concerns 17 patients admitted for care during a 5-year period. At their initial presentation, 94% of these patients manifested signs and symptoms of angioedema in the head and neck; three of them required urgent tracheotomy or intubation. As treatment of complement-mediated angioedema is distinct, an etiology-specific diagnostic and treatment protocol is presented. Of the patients, 35% had recent initiation of angiotensin-converting enzyme (ACE) inhibitor therapy for hypertension, and 6% demonstrated classic hereditary angioedema. However, the majority of them (59%) had unclear etiologies for their symptoms. Since angioedema is the final result of several possible abnormalities, a thorough knowledge of the differential diagnosis and clinical presentation is vital to patient management.