Bioelectronic options for a totally implantable hearing device for partial and total hearing loss

A semi-implantable electromagnetic hearing device (SIMEHD) for sensorineural hearing loss has been developed and tested in animals and limited clinical trial. The authors' electromagnetic transducer, which is the driver of the SIMEHD, when used in reverse mode is applicable to the fabrication of a bioelectronic microphone. Instead of being a driver, it transforms the sound-activated eardrum-ossicular vibration into an electric signal through the NdFeBo magnet implanted on the head of the malleus, interacting in a contactless manner with the electromagnetic coil.

Engineering principles applied to implantable otologic devices

The engineering principles of possible actuators and sensors for totally implantable mid-ear or cochlear hearing devices are summarized. The selection considerations are discussed. The frequency response, and the needed force and displacement at the ossicular chain sites were measured on fresh temporal bones to determine approximately the middle ear device requirements and design considerations. A design example of the actuator and sensor is outlined with laboratory and acute animal evaluation results.

The middle ear bioelectronic microphone for a totally implantable cochlear hearing device for profound and total hearing loss

BACKGROUND

A bioelectronic middle ear microphone (BMEM) has been developed in a laboratory bench model and successfully tested in fresh human temporal bones. A transducer actually has been bench-tested in our laboratory; it was implanted in chronic animal experiments (cats) as well as in humans for a period of 1 year as a driver of a semi-implantable electromagnetic middle ear hearing device (IDE, FDA approved). This BMEM is the result of the use of this same electromagnetic transducer used in a reverse mode. The applicability of the BMEM is for the development of a totally implantable cochlear implant using the eardrum as a diaphragm that transmits vibrations to a magnet cemented to the ossicles. This BMEM is to be powered by a lithium-ion implantable, rechargeable battery.

MATERIALS AND METHODS

To test the efficacy of this BMEM, the experiment was divided into two parts: (1) bench model, and (2) fresh human temporal bones, using an air-core electromagnetic (EM) coil and a ferrite core EM coil for comparison.

RESULTS

In the bench model, the average displacement at 3 kHz was 0.95 microns (peak) for 4 V p-p and 1.65 microns (peak) for 10 V p-p. At 5 kHz, the measurements were somewhat higher. In fresh human temporal bones, with sound source in the ear canal (60 dB HL and 90 dB HL), the result was better with the magnet implanted on the head of the malleus with the incus removed. The ferrite core EM coil with the magnet implanted on the malleus with the incus removed was compared with the air-core EM coil. At 60 dB HL, the ferrite core EM coil yielded more than four times the amplitude of the EM coil. At 90 dB HL, the ferrite core EM coil produced more than five times the amplitude compared with the air-core coil.

CONCLUSION

This BMEM using an EM ferrite coil and a permanent magnet on the head of the malleus is more efficient when compared with an EM air-core coil. This BMEM may be applicable to the construction of a totally implantable cochlear implant. Further research is necessary to integrate this BMEM with the other components of the design concept of the totally implantable cochlear implant.

Complications of rhytidectomy in an otolaryngology training program

OBJECTIVES/HYPOTHESIS

Complications of rhytidectomy have been widely reported in the literature. This study examines the incidence of complications after rhytidectomy in the hands of chief residents under appropriate attending supervision in an otolaryngology-head and neck surgery training program.

MATERIALS AND METHODS

The charts of 96 consecutive SMAS rhytidectomy patients were retrospectively reviewed. Patients were selected for surgery from a clinic designed exclusively for cosmetic facial surgery patients. This clinic was run by the otolaryngology chief resident and was supervised by an attending staff surgeon. Most patients elected local anesthesia and sedation administered by the surgical team. Submental liposuction was performed followed by SMAS plication rhytidectomy.

RESULTS

Follow-up ranged from 1 to 60 months. Complications included expanding hematoma (1%), temporary facial nerve weakness (3%), pretragal/mastoid skin slough (4.2%), permanent ear numbness (1%), hypertrophic scar (3.1%), wound infection (1%), and dissatisfaction with result (4%). There were no cases of permanent facial nerve injury.

CONCLUSION

These complication rates compare favorably with reported rates of larger studies over the past 30 years. These data support the conclusion that rhytidectomy can be performed safely by otolaryngology residents with little morbidity and good patient satisfaction.

External unit for a semi-implantable middle ear hearing device

A miniaturized, low-power external unit has been developed for the clinical trials of a semi-implantable middle ear electromagnetic hearing device (SIMEHD) which uses radio-frequency telemetry to couple sound signals to the internal unit. The external unit is based on a commercial hearing aid which provides proven audio amplification and compression. Its receiver is replaced by an application-specific integrated circuit (ASIC) which: 1) adjusts the direct-current bias of the audio input according to its peak value; 2) converts the audio signal to a one-bit digital form using sigma-delta modulation; 3) modulates the sigma-delta output with a radio-frequency (RF) oscillator; and 4) drives the external RF coil and tuning capacitor using a field-effect transistor operated in class D. The external unit functions as expected and has been used to operate bench-top tests to the SIMEHD. Measured current consumption is 1.65-2.15 mA, which projects to a battery lifetime of about 15 days. Bandwidth is 6 kHz and harmonic distortion is about 2%.

Effect of magnetic resonance imaging on a new electromagnetic implantable middle ear hearing device

OBJECTIVE

A 1.5-T magnetic resonance imager has been shown to be contraindicated for use in patients with pacemakers, cochlear implants, and neurostimulators. Our semi-implantable middle ear device uses a new adhesive bone cement. 4-META/MMA-TBB, for cementation of a 29-mg titanium-encased neodymium-iron-boron (NdFeB) magnet to the incus.

METHODS

Five NdFeB magnets and four solid titanium cylinders were cemented onto the incus of five preserved human temporal bones and two cadaver heads. They were all inserted into a magnetic resonance imager and evaluated for possible disruption.

RESULTS

Owing to the magnetic torque, the three magnets on the temporal bone were disrupted from the incus. The two cylinders on the temporal bones and the two cylinders and two magnets on the whole heads were not affected. The magnetic resonance imaging field did not affect the coercive force of the NdFeB magnets.

CONCLUSION

The large torque produced by a magnetic resonance imager may disrupt the magnet-cement and cement-incus interfaces, causing dislodgement. We postulate that patients with implantable magnets on the incus should not undergo magnetic resonance imaging testing.

Semi-implantable middle ear electromagnetic hearing device for sensorineural hearing loss

A semi-implantable middle ear electromagnetic hearing device (SIMEHD) is proposed for limited clinical trial in adult patients to evaluate the implantable hearing device for moderate to severe sensorineural hearing loss. Food and Drug Administration (FDA) investigational device exemption (IDE) approval has been granted (May 1996) for clinical trials. The implant unit has been evaluated acutely and chronically in animals (cats) with excellent results. Five cats undergoing chronic implantation were allowed to survive an average of 9.6 months, showing that the SIMEHD is biocompatible, functional and without untoward complications. All implant units recovered from the cats were functional, except for wire breakage of the internal antenna. A new antenna was redesigned for human implantation. The SIMEHD system consists of an external and internal unit. The external unit consists of a microphone, audio amplifier, modulator, radio frequency (RF) amplifier, antenna and battery. The internal unit is composed of a receiving antenna, hybrid electronic circuit, air core driving coil, and a target magnet cemented to the incus. All materials in contact with the body are biocompatible and expected to survive indefinitely. The implant unit is miniaturized and manufactured with existing fabrication technology by our industrial collaborator, Wilson Greatbatch, Ltd. The specific aims and major tasks of the proposed research are: a) to evaluate reliability, safety and efficacy of the SIMEHD system in a selected group of patients diagnosed with sensorineural hearing loss, due mainly to presbycusis or aging of the inner ear; and b) to obtain objective and subjective evaluation of audiologic and psychoacoustic performance as compared to the acoustic hearing aid. This paper describes the design, illustrates the actual device (newest prototype) and details the technique for surgical implantation in the attic and mastoid antrum in humans.

A new adhesive bonding material for the cementation of implantable devices in otologic surgery

BACKGROUND

Presently, there are no U.S. Food and Drug Administration (FDA)-approved adhesive bone cements for the surgical fixation of prosthetic materials in the middle ear. A promising new cement, 4-META/MMA-TBB opaque resin, has shown remarkable adhesive properties as a bone cement in vivo. The cement is composed of 4-methacryloyloxyethyl trimellitate anhydride (4-META) and methyl methacrylate (MMA) as monomers and tri-n-butyl borane (TBB) as an initiator.

METHODS

An electromagnetic semiimplantable hearing device presently under development was implanted into the middle ear of six cats using 4-META/MMA-TBB resin to cement a titanium-encased magnet to the incus. The animals were subsequently killed (at a mean of 9.6 months) to assess the (temporal bones and specifically the magnet-incus complex in each animal.

RESULTS

The titanium-encapsulated magnet was firmly adherent to all incuses without any failure of the cement-bone interface. Histopathologic examination of the implanted temporal bones demonstrated lack of middle ear inflammation. Transmission electron microscopy of the incuses demonstrated a unique "hybrid layer" in the bone-side subsurface of the bone-cement interface that elucidates the mechanism of interfacial adhesion.

CONCLUSIONS

Our investigation highlights the special biomechanical properties as well as the biocompatibility of 4-META/ MMA-TBB resin that make it an attractive bone-bonding agent for use in otologic surgery, including its potential usefulness during ossicular reconstruction.

Mechanical, acoustic and electromagnetic evaluation of the semi-implantable middle ear hearing device (SIMEHD)

The properties of the partially implantable middle ear hearing device (SIMEHD) were extensively studied. The internal unit was subjected to 5,000 cycles of bending at a force of 75 g (gravity) without failure. An accurate measurement of the force output of the SIMEHD was obtained (14-25 dynes/mA). This force is too small to cause any damage to the ossicular chain. The force resulting from electromagnetic interference over a wide frequency range (500 khz -1 Giga (10(9)) Hz) was measured and noted to be within the margin of safety. The frequency response plots (500-8,000 Hz) were also obtained and revealed an excellent ability to amplify middle and high-frequency sounds.

State of the art on the development of the implantable hearing device for partial hearing loss

This article summarizes the state of the art of the implantable hearing devices for partial hearing loss. Devices such as temporal bone stimulators and piezoelectric and electromagnetic middle and inner ear transducers are discussed. Cochlear implants are excluded. (See "Update on Cochlear Implantation" in this issue.) Those readers interested in a more in-depth study of implantable hearing devices should consult the February 1995 issue of The Otolaryngologic Clinics of North America which is dedicated to this matter (Guest Editor: Anthony J. Maniglia, MD).

Midfacial degloving for the management of nasal, sinus, and skull-base neoplasms

The midfacial degloving approach to the midfacial orbital and anterior skull base structures is very versatile. It provides excellent access to a wide range of resections, such as medial maxillectomy, radical maxillectomy with and without orbital exenteration, anterior skull base cranifacial resection, and partial rhinectomy. This technique is useful for removal of benign and malignant lesions. The postoperative complications are rare. Because of absence of external skin incisions the cosmetic results are excellent.

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.

Biomechanical assessment of a new adhesive bone cement for otologic surgery

The adhesion of metallic prostheses to bone is a major problem in otologic surgery. Conventional bone cements lack significant adhesive strength, which predisposes the cemented prosthesis to loosening. The advent of surgically implantable hearing devices is one example where an adhesive cement to secure metal to bone would be useful. The biomechanical properties of a new cement, 4-META/MMA-TBB opaque resin, were evaluated in an animal model. The cement is composed of 4-methacryloyloxyethyl trimellitate anhydride (4-META) and methyl methacrylate (MMA) as monomers and tri-n-butyl borane (TBB) as an initiator. Titanium disks were cemented to the tibias of rabbits, which were sacrificed at 0 and 90 days. Tensile and shear bond strengths between bone and metal were tested at both times. The mean baseline tensile and shear bond strengths were 8.92 MPa and 11.96 MPa, respectively. Adhesive failure occurred at the bone-cement interface. The decrease in bond strength at 90 days was minimal. Thus, 4-META/MMA-TBB cement is a promising new metal-to-bone adhesive that may be useful for the surgical fixation of metallic prostheses in otologic surgery.

Engineering principles of mechanical stimulation of the middle ear

This article presents the transducer principles of possible middle ear hearing devices with their characteristics and selection considerations summarized. The frequency response and the needed force and displacement at the ossicular chain sites were measured to determine approximately the system requirements and design considerations. The power required to vibrate the ossicular chain is estimated to be of the order of 0.1 watt, which is three orders of magnitude smaller than the power consumption of devices being developed in various laboratories. Careful engineering design and evaluation is needed. A design example of the transducer used with a partially implantable, noncontact electromagnetic hearing device is presented in this article with laboratory evaluation results.

The history and development of the implantable hearing aid

Implantable hearing aids have an interesting and colorful history. These devices have usually been investigational, but this has changed. Currently, several implantable devices are available for ongoing clinical trials in humans. They have promise in providing improved hearing in certain cases of conductive, mixed, and sensorineural hearing loss.

Contactless semi-implantable electromagnetic middle ear device for the treatment of sensorineural hearing loss. Short-term and long-term animal experiments

A contactless electromagnetic hearing device has been designed following basic science experiments, improvement of electronics, and precision micromechanics. Different prototypes have been developed and tested in the laboratory, fresh human temporal bones, and acute and chronic animal experimentation. A conductive hearing loss model was first developed in the cat using samarium cobalt as the target magnet. Later, a highly efficient electromagnetic air-core coil was selected to vibrate a neodymium iron boron magnet cemented to the body of the incus and tested in acute and chronic experiments using the cat as the model. In this group of animals, the ossicular chain was left intact. There was no failure of the target magnet, driving coil, or implanted electronics. The only problem encountered in this evaluation was a malfunction of the receiving antenna that had to be redesigned and retrofitted into the implanted units. This system would be suitable for the treatment of moderate to severe sensorineural hearing loss. Planning to begin human clinical trials is ongoing.

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.

Chondrosarcoma of the larynx: challenges in diagnosis and management

Chondrosarcoma is a rare neoplasm of the larynx with approximately 200 cases reported in the literature. The infrequent occurrence of this neoplasm, and its indolent pattern of growth, can result in a delayed or missed diagnosis, thereby jeopardizing the preservation of laryngeal function. Four cases of chondrosarcoma of the larynx are presented demonstrating the challenges in the diagnosis and management of this neoplasm. Conservation surgery remains the mainstay of therapy aiming towards preservation of the framework and function of the larynx. Two innovative reconstructive techniques are presented which made conservation laryngeal surgery possible in two of the four patients. Indeed, surgical resection with sound oncologic principles must be applied and total laryngectomy may be necessary. On rare occasion radiotherapy may be used, although its value remains controversial.

A contactless electromagnetic implantable middle ear device for sensorineural hearing loss

Following basic science experiments, improvement of precision micromechanics and electronics design, and development of different prototypes, a contactless electromagnetic hearing device has been successfully implanted in cats (acute experiments). Chronic animal experiments using the cat as well as the rabbit are ongoing to test the components of the device. A highly efficient air core coil is used to vibrate a neodymium-iron-boron magnet cemented to the body of the incus. The parts of the system, including implanted electronics (hybrid circuit, solid state), are laser welded and hermetically sealed. The system allows for the generation of enough force which vibrates the magnet implanted on the incus. It would be suitable for the treatment of moderate to severe sensorineural hearing loss.

Uvulopalatopharyngoplasty for obstructive sleep apnea in adults: clinical correlation with polysomnographic results

The success of Uvulopalatopharyngoplasty (UPPP) for Obstructive Sleep Apnea (OSA) can be assessed by a variety of parameters including clinical evaluation and polysomnography (PSG). Patients are often reluctant to undergo post-operative testing and insurance companies are often unwilling to reimburse for expensive overnight sleep studies. Due to the reality of these medical and economical problems, can a clinician be confident of the success of UPPP based solely on clinical evaluation? Sixty patients underwent UPPP for the treatment of OSA from July 1987 through June 1992. Patients treated with tracheostomy or other methods were not included in this study. Fifty-three patients (88%) reported an improvement in their symptoms of snoring, daytime somnolence, morning headache and apnea. Twenty-one patients (35%) had post-operative PSG. Eighteen of 21 patients (85%) reported improvement in their symptoms. Eleven of 21 patients (57%) showed objective improvement in their sleep apnea. The objective findings of PSG do not correlate, in a significant number of patients, with subjective clinical improvement of patients treated with UPPP.

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.

Conservative medical management of traumatic pharyngoesophageal perforations

Traditionally, surgical treatment has been the acceptable management for perforation of the pharyngoesophageal tract secondary to blunt and penetrating trauma. From July 1983 to June 1990, we managed 10 patients with this type of lesion by a conservative medical management approach. Mirror or fiberoptic flexible laryngoscopy was performed in the majority of cases to ascertain the nature of the injury. An esophagogram is very helpful to locate and evaluate the extent of the injury. All patients were treated with broad-spectrum intravenous antibiotic therapy and no oral feeding. There were no complications or need for surgical treatment in any of the cases. The head and neck surgeon, in selected cases, should consider the possibility of using conservative management of pharyngoesophageal perforations. This approach has proven in our hands to be relatively safe and cost-effective, resulting in no disability or prolonged hospitalization of our patients. This study involves two institutions (two affiliated hospitals of Case Western Reserve University School of Medicine) with different surgeons selecting appropriate antibiotic therapy. It is a retrospective review. No controls were made by random selection of cases treated surgically. These cases, if not properly managed, may lead to fatal outcomes.

Different options for treatment of inverting papilloma of the nose and paranasal sinuses: a report of 41 cases

Forty-two cases of inverting papilloma of the nose and paranasal sinuses were reviewed from 1972 to 1989. Forty-one patients underwent surgical excision. Of those patients followed up for at least 6 months, lateral rhinotomy was performed in 14 patients and midfacial degloving in 9 patients. The recurrence rates were 29% and 22%, respectively. The other 10 patients underwent excision through an external ethmoidectomy, Caldwell-Luc operation, or intranasal approach. There were five patients (12%) diagnosed with squamous cell carcinoma associated with inverting papilloma. The correlation of malignancy with proptosis, visual changes, infraorbital hypesthesia, and skull base involvement on presenting symptomatology is noted. Inverting papilloma is a benign neoplastic lesion that shows variable aggressiveness. A computed tomography (CT) scan evaluation is very important for the work-up. An aggressive wide surgical excision is best performed through an open approach. The approach for surgical removal should be based on the location and extension of the lesion. A graduating approach from a lesser to a more major excision is advocated even though a risk exists of having to reoperate in about one fifth of the patients who experience a recurrence. A secondary surgical excision, even with craniofacial resection, is essential to eradicate disease in cases of recurrence. Close follow-up is necessary. Further surgery may be indicated. Post-operative radiation therapy is recommended if malignancy is indeed present.

Fatal and other major complications of endoscopic sinus surgery

Endoscopic sinus surgery has become an acceptable technique for the treatment of chronic sinus disease. This report analyzes five complications which came to my attention. Two cases were orbital:1 bilateral blindness due to damage of the optic nerves, and 1 damage of medial rectus muscle. The other 3 cases were intracranial:two cribriform plate damage with frontal lobe injury and hematoma, and 1 damage of the anterior cerebral artery, resulting in death. This rather novel technique, especially when used by less-experienced surgeons, has major complications similar to what has been reported with the traditional intranasal sphenoethmoidectomy. Knowledge of anatomy, good training, and meticulous surgical technique are very important. Endoscopic sinus surgery in patients with extensive pathology should be used with caution, especially if general anesthesia is selected or if excessive bleeding occurs. It would be beneficial to otolaryngologists to have previous experience in the traditional technique before adopting endoscopic sinus surgery to their armamentarium. Even then, major complications may occur in the hands of very experienced surgeons. Early recognition and proper management of these complications are of utmost importance in order to minimize disability or prevent death.

Cranial nerve injuries following carotid endarterectomy: an analysis of 336 procedures

Cranial nerve injuries may result from carotid endarterectomy. From January 1984 to December 1987, a total of 336 carotid endarterectomies were performed at University Hospitals of Cleveland and Cleveland Veterans Administration Hospital. Forty-five cranial nerve injuries were documented (13.5%). Twenty patients (6%) had documented unilateral vocal cord paralysis, 16 (4.8%) had hypoglossal injuries, 8 (2.4%) had facial nerve paresis, and 1 (0.3%) had an injury to the spinal accessory nerve. Although most injuries were due to either retraction or edema of cranial nerves, long-term follow-up regarding recovery of function is very important. We feel that proper clinical evaluation of these patients should be routinely done preoperatively in order to document possible preexisting cranial nerve deficits. Postoperatively, if symptoms of possible cranial nerve abnormalities occur, these patients should have a thorough head and neck evaluation in order to identify possible lesions and institute further treatment to improve their quality of life.

Maxillary ameloblastoma: case report

Ameloblastoma of the maxilla is an unusual epithelial tumor of odontogenic origin. Although it is considered benign, it can behave in a slowly growing infiltrative fashion, with multiple recurrences and eventual intracranial, or even distant, spread. Information on this tumor consists, to a large extent, of case reports presented in the oral surgery literature. This study is a retrospective review of our combined institutional experience with nasomaxillary tumors from 1980 to 1988. Among these cases were four patients with maxillary ameloblastoma, two males and two females, ranging in age from 16 to 66 years at presentation. Disease extent varied from ameloblastoma localized to a cyst in the maxillary sinus to extensive maxillary and ethmoid involvement. Follow-up ranged from 2 to 13 years, and disease course varied from apparent disease control to persistent intracranial tumor, despite attempts at extirpation. An analysis of this experience and the related literature is presented, along with recommendations for radical therapy, when appropriate, to best ensure control.

Metronidazole in head and neck surgery--the effect of lengthened prophylaxis

Previous studies of antibiotic prophylaxis have shown that treatment for 24 hours has been beneficial for head and neck surgery and that longer periods of antibiotic therapy have not improved results. Metronidazole (Flagyl), unlike other antibiotics tested, has been shown to be effective in an experimental abscess, even if treatment is begun up to 120 hours after administration of inoculum. This article presents a prospective, randomized, multifactorial study comparing a brief vs. a prolonged duration of metronidazole and cefazolin prophylaxis in 50 consecutive patients with a head and neck cancer undergoing operation. Patients receiving 2 days vs. 7 or more days of antibiotic prophylaxis were compared. Statistical analysis of data demonstrated a striking reduction in severity of wound complications and a reduced incidence of wound infections in the group treated with 7 or more days of antibiotic prophylaxis.

Intraoral-extramaxillary sinus approach for ligation of the maxillary artery: an anatomic study with clinical correlates

Surgical control of severe epistaxis is usually reserved for cases refractory to more conservative techniques. We present our experience with intraoral ligation of the maxillary artery as it courses through the buccal fat pad before it enters the pterygopalatine fossa and branches posterior to the maxilla. This technique has been found useful in the control of nasal hemorrhage as well as an adjunct to other surgical procedures, such as removal of benign and malignant neoplasms involving the maxilla and paranasal sinuses. This technique was used for ligation of the maxillary artery in 20 patients. The artery was readily identified in some cases, but required more extensive dissection in others; therefore, an anatomic study in 18 preserved and fresh cadaver specimens was undertaken to investigate the variability of the maxillary artery in the region of the buccal fat pad. There appeared to be significant variation in the distance from the buccal mucosal incision site, as well as variation in the relationship to the pterygoid muscles. This relationship to the pterygoids explains the occasional difficulty in locating the artery for ligation. This technique represents a reasonable alternative to the more traditional transantral approach to ligation of the maxillary artery, as long as the surgeon understands the anatomy of the region, its variations, and where the artery may be located if not immediately apparent. No major complications have been experienced.

Intracranial abscesses secondary to nasal, sinus, and orbital infections in adults and children

Nineteen cases of intracranial abscesses secondary to infection of the midface are reported. The most common underlying cause was bacterial sinusitis. Other etiologic factors included mucormycosis following steroid therapy, Wegener's granulomatosis, nasal dermoid cyst and sinus tract, tooth abscesses, aspergillosis following chemotherapy for leukemia, squamous cell carcinoma of the frontal sinus, infected methylmethacrylate plate for a prior skull fracture, and a case of gauze packing left in the sinus following surgery. Anaerobic organisms were the predominant cause of the abscesses. The most dangerous intracranial complication was subdural abscess, which occurred in seven patients in this series. Three of them died. Four cases of frontal and parietal lobe abscesses were treated with systemic antibiotics only. This approach has not been well emphasized in our literature. Steroid therapy should not be used for the treatment of sinus and orbital infections. It can result in dreadful complications. The overall mortality rate in this series was 21% (4 of 19), despite aggressive treatment and close cooperation between the neurosurgeon, otolaryngologist, and other specialists. Early diagnosis and adequate treatment are paramount.

Tracheogastric puncture for vocal rehabilitation following total pharyngolaryngoesophagectomy

Speech rehabilitation postpharyngolaryngoesophagectomy has not received significant emphasis. We describe our experience with five patients who underwent a delayed tracheogastric puncture (TGP) after pharyngogastric anastomosis. When compared to patients who had undergone tracheoesophageal puncture (TEP) after laryngectomy, speech intelligibility and fluency were adequate for conversational speech, but voice quality was characterized by lower pitch, reduced intensity, slower rate, and a "wet" quality. There were no complications related to the TGP. TGP is a safe and often useful procedure for voice and speech restoration in patients who have undergone total pharyngolaryngoesophagectomy and pharyngogastric anastomosis.

Newer technique of laryngeal reinnervation: superior laryngeal nerve (motor branch) as a driver of the posterior cricoarytenoid muscle

This report analyzes the experience gained using two different techniques to reinnervate the paralyzed vocal cord. In the neurotization group, the superior laryngeal nerve (SLN) motor branch-cricothyroid muscle pedicle was used to reinnervate the posterior cricoarytenoid muscle. In the direct nerve anastomosis group, the SLN was anastomosed to the abductor branch of the recurrent laryngeal nerve (RLN), and the ansa hypoglossi (AH) to the adductor branch of the RLN. A third group of animals (control) had the right RLN sectioned without any anastomosis. About 5 to 6 months postoperatively the animals were killed painlessly and evaluated. The neurotization group revealed vocal fold mobilization on the right side to have an average of about half of the mobility of the left, normal side. After the RLN and SLN on the left were severed as well as the AH bilaterally, the vocal cord mobility was reduced to about one fourth. The direct nerve anastomosis group showed about fourfold less vocal cord mobility than the neurotization group. After the SLN, RLN, and AH were severed bilaterally, the control group showed no vocal cord mobility. The neurotization technique has been selected for further experimentation in human adults.

Speech restoration and complications of primary versus secondary tracheoesophageal puncture following total laryngectomy

The tracheoesophageal (TE) fistula with a speech prosthesis has become the method of choice for vocal rehabilitation in many postlaryngectomy patients. Several modifications of the procedure have been described including primary TE puncture at the time of laryngectomy. Fear of increased risk of complications has kept the primary procedure from widespread usage. Our series of 95 TE fistula procedures from 1980 to 1988 revealed 33 to be primary and 62 secondary. Eighty-five percent (85%) (28 of 33) patients in the primary group achieved long-term satisfactory speech (1 year or more of follow-up). Complications occurred in 36% of this group of patients. The success rate for the secondary group was 69% (43 of 62), while the complication rate was 21%. There were no instances of death, sepsis, or mediastinitis associated with either primary or secondary TE fistula patients. It appears that the primary TE fistula can be performed as safely and effectively as the secondary procedure.

Fatal and major complications secondary to nasal and sinus surgery

The purpose of this study was to review 40 major or fatal complications secondary to nasal and sinus surgery that were referred to the author for consultation or other reasons. The most frequent complications were intracranial, which occurred in 13 cases, and resulted in four deaths. Blindness occurred in ten patients (two bilaterally). Three other fatalities resulted from internal carotid artery damage. Three patients died of anesthesia-related problems and one survived malignant hyperthermia. In all, ten patients died as a result of intracranial catastrophe, hemorrhage, or general anesthesia complications. Although some complications are preventable, others may be unavoidable, even in the hands of well-trained, experienced surgeons.

Preservation of hearing in the surgical removal of cerebellopontine angle tumors

It is claimed that postsurgical hearing preservation is possible in about 5 to 8 per cent of cases of acoustic neuroma. Even with small tumors, hearing preservation can be accomplished in about half of the patients who are fortunate to have anatomic integrity of facial and cochlear nerves, as well as intact inner ear blood supply at the end of the surgical procedure. Monitoring of seventh and eighth nerve function through evoked potentials may be important. On the other hand, even if evoked potentials are preserved during surgery with wave V latency and amplitude similar to preoperative recording, hearing may still be completely lost during the immediate postoperative period. There is no predictable pattern that assures postoperative preservation of hearing. In Case 2, the seventh and eighth nerves as well as the inner ear blood supply were carefully dissected and anatomically and electrophysiologically preserved during the intraoperative period. At the end of the surgical procedure, the evoked potentials were the same as preoperatively. Nevertheless, the patient ended up with no detectable hearing postoperatively. We feel that the suboccipital-retrosigmoid transcanal approach can be safely used for the removal of cerebellopontine angle tumors of all sizes. We believe the argument that "only the translabyrinthine approach can accomplish total tumor removal" is not valid. No complications have been attributed by having the patient in the semisitting position. Older patients, who cannot tolerate the semisitting position, are operated on while in the park bench position. Planned subtotal removal of a CPA tumor is done with the patient in the supine position (transmastoid-retrolabyrinthine or retrosigmoid). The relationship between the otologic surgeon and neurosurgeon is very important. The surgical approach used should be selected on the basis of the combined experience of the surgical team. Finally, an attempt should be made to preserve facial nerve function and hearing in all suitable patients. The postoperative course using the suboccipital-retrosigmoid approach is usually benign, and the patients are discharged from the hospital between 7 and 10 days following surgery. The translabyrinthine approach, in our opinion, should be reserved for smaller lesions in patients with anacusis or with residual hearing that is not worth saving.

Implantable hearing devices. State of the art

The use of implantable hearing devices to help persons with conductive hearing loss is still in its infancy. The advantages and disadvantages of the various models of implantable hearing devices currently being developed are discussed. Their clinical use is described, and the potential benefits of each are presented.

Direct nerve implantation vs. nerve-muscle pedicle: a comparative study of reinnervation in the rabbit

To determine the optimal method for reinnervation of the paralyzed head and neck musculature, we compared direct muscular nerve implants (DNI) with nerve-muscle pedicles (NMP) in rabbits. In 25 anesthetized animals, one ansa hypoglossi nerve was cut. Five animals served as controls and two groups of 10 each received cross-over DNIs or NMP from one sternothyroid to the contralateral sternohyoid muscle. The transplanted nerves of animals that survived long enough for neurotization to occur (8 DNIs, 5 NMPs) were stimulated with 3 to 10 mA. 0.05 msec pulse trains to obtain force curves from corresponding straps. Fiber diameters and areas were calculated on muscles harvested before the animals were killed. There was a nonsignificant trend toward stronger contraction in the NMP group, but NMP fibers were significantly larger than those in DNI and control groups (p less than 0.001).

Newer techniques of laryngeal reinnervation

We relate the experience obtained in the use of the right superior laryngeal nerve (motor branch)--cricothyroid muscle pedicle flap in dogs in an attempt to reinnervate the right posterior cricoarytenoid muscle (PCA). The right vocal cord was paralyzed by severance and removal of 2.5 cm of the right recurrent laryngeal nerve. Evaluation 6 months postoperatively revealed the vocal fold remobilization on the right side to have an average of about one half the mobility of the left, normal side. After the recurrent laryngeal and superior laryngeal nerves on the left were severed, the vocal cord mobility dropped to only about one fourth. This suggests that the dogs had contralateral reinnervation. Nevertheless, the right vocal cord mobility, driven only by the right superior laryngeal nerve, was enough to secure an adequate airway without the need for a tracheotomy. This experiment was statistically significant on comparison with a control group. Electromyographic studies as well as PCA histochemistry were performed.

Adenotonsillectomy. A safe outpatient procedure

Traditionally, adenotonsillectomy in children and tonsillectomy in adults have been performed as inpatient procedures. Our experience with this procedure as outpatient started in 1975 at the University of Miami-Jackson Memorial Medical Center. From 1975 to 1987, 1428 cases performed in Florida and Cleveland were reviewed to evaluate the safety and efficacy of the technique used. Bismuth subgallate and epinephrine mixture for hemostasis is used without relying on electrocautery, ties, or suture technique to control bleeding. The incidence of immediate and delayed postoperative bleeding in a series of patients was extremely low (four [0.28%] of 1428 cases). Our technique has good hemostatic properties allowing vessels to contract and retract into the muscle of the tonsillar fossae and adenoid bed. Bismuth subgallate activates factor XII (Hageman factor) and, therefore, markedly accelerates the cascade of blood clotting. Outpatient adenotonsillectomy is safe, cost-effective, and minimizes psychologic implications, which may be an important factor, especially in children. Ambulatory adenotonsillectomy has not been well emphasized in the literature.

Electromagnetic implantable middle ear hearing device of the ossicular-stimulating type: principles, designs, and experiments

This report analyzes the principles, describes designs, and discusses the advantages and disadvantages of different types of implantable middle ear hearing devices. Preliminary acute experiments using an electromagnetic transducer for an implantable hearing device of the ossicular-stimulating type were performed in cats. A miniature samarium cobalt rare earth magnet was cemented on the head of the stapes. An electromagnetic coil powered either by direct wiring or by telemetry was used to stimulate the stapes. The performance of the system was evaluated by electrophysiologic assessment of hearing (brain stem evoked response potentials). The findings showed that the device is functional with good "implant gain" (35 dB average) and consumes reasonably low current (0.6 mA) with telemetry. Further investigation is necessary in order to develop an implantable middle ear hearing device with successful clinical application.

Activation of Hageman factor (factor XII) by bismuth subgallate, a hemostatic agent

Bismuth subgallate is an effective agent in preventing hemorrhage after adenotonsillectomy. The experiments described demonstrate that this may occur through the activation of Hageman factor by this agent. Bismuth subgallate shortened the clotting time of whole blood, an action localized to an effect on the early steps of the intrinsic pathway; bismuth subgallate did not accelerate the thrombin time or prothrombin time of normal plasma, but could be substituted for kaolin as an activator of coagulation in assays of the partial thromboplastin time. The action of bismuth subgallate was localized to an effect on Hageman factor. It did not induce coagulation of plasma samples deficient in any of the recognized factors participating in the intrinsic pathway of thrombin formation, but it shortened the clotting time of plasma deficient in factor VII, a component of the extrinsic pathway. Evidence was obtained that Hageman factor exposed to bismuth subgallate corrected the defect of Hageman factor-deficient plasma and acquired amidolytic properties in the absence of other clotting factors. These studies provide a rationale for the hemostatic properties of bismuth subgallate.

Peritonsillar and neck abscesses in the pediatric age group

A retrospective study was performed on 93 abscesses in children admitted for diagnosis and treatment at Rainbow Babies and Childrens Hospital, University Hospitals of Cleveland, during a 15-year period from 1972 to 1987. Forty-five percent were peritonsillar, 20.5% superficial neck, 21.5% submandibular-submental, 9.6% retropharyngeal, and 3.4% parapharyngeal. All four complications resolved without sequelae. Early diagnosis and adequate treatment were of paramount importance to achieve a low complication rate and a short hospital stay. Bacteriology and antibiotic therapy, as well as surgical treatment, are discussed.

Dynamic rehabilitation of the paralyzed face: I. Electronic control of reinnervated muscles from intact facial musculature in the rabbit

An entirely satisfactory solution to dynamic rehabilitation of the paralyzed facial musculature has not yet been found. Recent interest in selective reinnervation of the laryngeal musculature, synchronous with appropriate afferent information, has led us to propose that miniature strain gauges be placed on one or more muscles of facial expression on the intact side to channel electrical signals to the opposite corresponding facial musculature reinnervated via nerve-muscle pedicles. In order to avoid introducing extraneous factors related to facial motion, this principle was first studied on crossover ansa hypoglossi nerve-muscle pedicles in New Zealand white rabbits. Surgery was performed on a total of five animals that were under general anesthesia with xylazine and ketamine, through a midline neck incision. The animals were reexplored after 12 weeks, and after verification that reinnervation had taken place, a vertical incision was made under the external canthus, in order to expose the facial nerve. A miniature strain gauge was then sutured on the facial musculature and connected to a central modulating unit that was, in turn, linked to the nerve-muscle pedicle via a monopolar electrode. Facial wiggle that resulted from direct electrical facial nerve stimulation caused synchronous contraction of all reinnervated strap muscles under study; this was documented on film and through facial and strap muscle activity tracings. Our next step will be to extend this principle to paralyzed facial muscles. If successful, this system could be miniaturized for long-term implantation in human beings.