Biomedical subjects
Publications and source records attributed to J L Kemink.
The resources and areas of expertise necessary to establish and maintain a successful children's cochlear implant program is discussed. Insights based on experience with a pediatric patient population are presented.
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Initial reports of the use of parenteral streptomycin for bilateral Meniere's disease (MD) have demonstrated success in reducing the vestibular symptoms and, in some patients, stabilizing hearing. The long-term follow-up (mean, 5.1 years) of 19 patients treated with intramuscular streptomycin for bilateral MD is presented. The amount of streptomycin administered (5 to 50 g) was determined by clinical symptoms and by serial testing of the reduction in the slow-phase velocity on electronystagmography. Episodic vertigo was totally relieved in 12 patients and improved in severity and frequency in an additional 4 patients. Permanent posttreatment dysequilibrium occurred in 47% of the patients treated. The changes in hearing (speech reception threshold) were independent of the therapeutic effect of streptomycin on the vestibular system. The overall results suggest that the intramuscular titration of streptomycin should continue to be considered as one of the therapeutic options in patients with disabling vertigo due to bilateral MD.
Chronic vestibular dysfunction is often a frustrating problem for both patient and physician. A program of customized vestibular habituation therapy is introduced and its efficacy in a group of 65 patients is evaluated. Preliminary findings suggest that 59% of patients will have a dramatic improvement, after which their vestibular symptoms no longer cause any restriction in their lifestyles. An additional 23% of patients note considerable improvement, but have persistent symptoms that continue to restrict their activities. Vestibular habituation therapy is a rational, multidisciplinary approach to the treatment of chronic vestibular dysfunction that is a significant alternative to traditional pharmacologic management. Failure of vestibular compensation after involvement in a disciplined program of habituation therapy constitutes a much stronger indication for vestibular surgery in patients with unilateral peripheral lesions.
Three-dimensional x-ray computed tomography (3DCT) has been useful in planning surgical procedures involving craniofacial reconstruction, the pelvis, hip, spine, knee and shoulder. The clinical use of 3DCT in temporal bone surgery has not been evaluated. We used 3DCT to assess temporal bone anatomy in 9 patients. These cases evaluated two encephaloceles, two postinflammatory dehiscences, two temporal bone fractures, one glomus jugulare tumor, one acoustic neuroma, and one meningioma. We found 3DCT useful in these temporal bone applications as a supplement to standard two-dimensional CT scanning (2DCT). While 3DCT provided a better preoperative understanding of the underlying anatomy, no treatment was modified solely on the basis of the information derived from the 3-D presentation of data. We conclude that, although 3DCT images have some qualitative advantages over 2DCT techniques, their value in further defining temporal bone morphology must be evaluated against the cost entailed by their use.
Advances in the diagnosis and intraoperative management of acoustic neuromas have greatly reduced the incidence of neurologic deficits following their removal. Ninety-three patients underwent acoustic tumor removal during a 41/2-year period, and hearing preservation was attempted in 20 cases. Hearing was preserved in 65% of the entire series, and excellent results were obtained in tumors less than 1.5 cm. No patient with a tumor greater than 1.5 cm had serviceable hearing preserved when total tumor removal was performed. Two patients, one with neurofibromatosis and one with an acoustic neuroma in an only-hearing ear, had planned partial tumor removal with preservation of hearing. Preoperative auditory brainstem response results were not predictive of postoperative hearing preservation. Intraoperative auditory brainstem response monitoring demonstrated that loss of wave V consistently correlated with loss of hearing postoperatively, whereas persistence of wave V (with a latency prolongation not exceeding 3.00 ms) was predictive of successful hearing preservation regardless of latency increases.
Three hundred ninety-seven patients with 407 cutaneous malignancies of the auricle, periauricular region, and cartilaginous external ear canal were reviewed. Tumors were most commonly located in the preauricular and postauricular regions, followed by the helix, concha, antihelix, and ear canal. All lesions were excised with Mohs microscopic control of margins. For lesions requiring lateral temporal bone resection, an adaptation of fresh-tissue microscopic control was used to analyze deep and anterior margins suspected of harboring residual tumor. Two-year minimum follow-up of 229 patients with periauricular and auricular tumors (N = 231 tumors) and 14 patients with cartilaginous ear canal tumors (N = 14 tumors) revealed recurrence rates of 6.9% and 14.3%, respectively. Recurrences were most common in cases of large tumors (greater than 2.5 cm), basal cell carcinomas with morphea elements, and multiply recurrent lesions. We conclude that Mohs surgery is comparatively effective, though not uniformly curative, and can be adapted to supplement excision of large tumors in these regions.
Pseudohypoparathyroidism (PHP) is a heterogenous syndrome resulting from bone and renal resistance to parathyroid hormone (PTH). Hypocalcemia and hyperphosphatemia occur despite elevated PTH levels. Head and neck manifestations of PHP include tetany, laryngeal spasm, and ectopic calcification in the eye, dentition, subcutaneous tissue and brain. The first case of malleus head fixation caused by ectopic calcification in a PHP patient is reported. Normalization of serum calcium and phosphate levels does not appear to retard or correct this abnormality. Ossiculoplasty or amplification is currently the recommended treatment in PHP patients with malleus head fixation.
Transmastoid labyrinthectomy has continued to be an important part of the surgical armamentarium for patients with vertigo and nonserviceable hearing loss. Continuing experience substantiates our earlier impression that the vestibular system usually accommodates rapidly to complete unilateral surgical ablation, regardless of age or degree of residual vestibular activity in the ear (as measured by preoperative bithermal caloric testing). Although the symptom of vertigo is reliably treated by transmastoid labyrinthectomy, a patient questionnaire has demonstrated a significant incidence of mild to moderate persisting postoperative dysequilibrium. Although this dysequilibrium is usually not debilitating, this questionnaire has demonstrated its existence more precisely than a retrospective review of the patients' clinical records. This study reviews 110 patients who underwent labyrinthectomy between 1978 and 1985. We remain impressed at the efficacy of the transmastoid labyrinthectomy in relieving the symptom of vertigo.
Auditory brainstem response testing has been a major breakthrough in audiologic screening for acoustic neuroma because of its high degree of sensitivity. Although it is not uncommon for other cerebellopontine angle masses to present with normal ABR findings, reports of eighth nerve tumors with false-negative auditory brainstem response tests are quite rare. A series of 120 acoustic neuromas resected at the University of Michigan was reviewed and revealed two such patients. These two patients presented with asymmetric sensorineural hearing loss and unilateral tinnitus and were found to have completely normal auditory brainstem response. The diagnosis of acoustic neuroma would have been delayed if a comprehensive evaluation had not been pursued.
The middle components of the auditory evoked response (middle latency response, MLR) were evoked by acoustic clicks from the normal-hearing ear and by charge-balanced biphasic current pulses from the severe-to-profoundly hearing-impaired ears of patients undergoing labyrinthectomy for the management of intractable vertigo. A vertex-positive peak with a latency ranging from 27 msec to 38 msec (Pa) was characteristic of both the electric and the acoustic MLR. In subjects, the electric Pa always preceded the acoustic Pa in latency. In addition, the electric Pa had a sharper appearance than did the acoustic Pa. The electric MLRs were elicited by a range of stimulus intensities and persisted after the completion of labyrinthectomy.
Intraoperative facial nerve monitoring provides a potentially useful adjunct to recent surgical advances in neurotology and neurosurgery. These measures further aid the surgeon in preserving facial nerve function by enhancing visual identification with electrical monitoring of mechanically evoked facial muscle activation. Facial nerve monitoring in neurotologic surgery may achieve the following goals: (1) early recognition of surgical trauma to the facial nerve, with immediate feedback made available to the surgeon through monitoring of mechanical activation; (2) assistance in distinguishing the facial nerve from regional cranial nerves and from adjacent soft tissue and tumor with selective electrical stimulation; (3) facilitation of tumor excision by electrical mapping of portions of tumor that are remote from the facial nerve; (4) confirmation of nerve stimulability at the completion of surgery; and (5) identification of the site and degree of neural dysfunction in patients undergoing nerve exploration for suspected facial nerve neoplasm or undergoing decompression in acute facial palsy. This paper provides an overview of intraoperative facial nerve monitoring principles and methodology and reports a recent clinical investigation that demonstrates the utility of facial nerve monitoring in translabyrinthine acoustic neuroma surgery.
Improvement of hearing after excision of an acoustic neuroma has been observed infrequently. We present a case of dramatic recovery of hearing in a patient with a 1-cm acoustic neuroma whose pure-tone thresholds and speech discrimination had profoundly deteriorated while she awaited surgical therapy. Postoperatively, her hearing in the affected ear is equal to that in her other ear, and her speech discrimination exceeds that of her best preoperative audiogram. Issues related to hearing preservation and improvement after acoustic tumor surgery are discussed.
Current techniques for ossicular reconstruction include ossicular autografts and homografts, and plastic and ceramic prostheses. Experimental testing of ceramic materials has led to the development of a nonporous, bioactive form of glass ceramic (Ceravital) for tympanoplastic reconstruction. To determine the clinical usefulness of these implants, Ceravital ossicular reconstructions were evaluated in 37 patients treated at the University of Michigan Medical Center during an 18-month period. Thirty-two patients (86%) with chronic ear disease underwent Ceravital ossicular reconstruction with tympanoplasty with or without mastoidectomy. Five other patients (14%) underwent ossicular reconstruction--2 for congenital anomalies, 2 for temporal bone trauma, and 1 patient for glomus tympanicum removal. Patient follow-up ranged from 2.2 to 3.8 years, with a mean follow-up period of 2.9 years. Prosthesis extrusion occurred in one case (3%). Mean preoperative and postoperative (2-year) pure tone air-bone gaps were 41.6 dB and 21.3 dB, respectively. Hearing was improved in 35 of 37 patients (95%). Postoperative pure tone air-bone gap was closed to 20 dB or less in 23 patients (62%). Hearing gains were greater with partial rather than total reconstructions (p = 0.14) and significantly greater with intact canal wall rather than canal wall down tympanoplasties (p less than 0.05). Initial results obtained with the Ceravital ossicular prosthesis compare favorably with those obtained using other methods of alloplastic reconstruction. These preliminary data suggest that Ceravital is an effective alternative prosthetic material for ossicular reconstruction.
Wound infection, cerebrospinal fluid leak, and meningitis are serious potential complications of neurotologic procedures that transgress the posterior cranial fossa dura. A study of 236 patients was made to determine the effect of perioperative intravenous antibiotics and topical bacitracin irrigation on the incidence of these complications. Of the 236 patients, 170 (72%) underwent translabyrinthine resection of acoustic tumors, while 66 (28%) underwent retrolabyrinthine vestibular nerve section. Patients were divided into four groups: those who received no antibiotics, those who received perioperative intravenous antibiotics only, those who received topical bacitracin irrigation only, and those who received a combination of perioperative intravenous antibiotics and topical bacitracin irrigation. There were no untoward effects of either perioperative intravenous antibiotics or topical bacitracin. The results indicate that bacitracin irrigation reduced the incidence of wound infection from 9% to 2% (p less than 0.05); of cerebrospinal fluid leak from 12% to 5% (p less than 0.04); and of all targeted complications combined from 22% to 9% (p less than 0.006). Furthermore, the topical bacitracin irrigation only group showed a statistically significant reduction in wound infections compared to the perioperative intravenous antibiotic only group (p less than 0.02). The incidence of meningitis was statistically unaffected by any of our treatment protocols.
As a result of advances in neuro-otology and neurosurgery, surgeons often operate in the vicinity of sensitive and delicate neural structures in an attempt to restore their function, remove tumor, or alleviate distressing and disabling symptoms. Concerns about preservation of neural function during these surgical procedures have provided the need and motivation for the development and adaptation of neurophysiologic techniques designed to provide feedback about impending trauma. The most common functions that are at risk in neuro-otologic surgery are related to the auditory nerve and centers and the facial nerve. This paper deals with principles and practices of intraoperative monitoring of auditory function. The following applications are illustrated and discussed: 1) intraoperative monitoring of auditory function during posterior fossa tumor resection, 2) auditory brain stem response and VIIIth nerve monitoring during retrolabyrinthine vestibular nerve section, 3) monitoring of auditory function during microvascular decompression of cranial nerve VII, VIII, or IX, and 4) special applications related to cochlear implant surgery.
Electric middle-latency auditory evoked responses (EMLRs) to transtympanic promontory stimulation were obtained from 19 of 22 ears of profoundly hearing-impaired patients evaluated for cochlear implant candidacy. The EMLRs were characterized by positive polarity peaks with latencies ranging from 20 to 30 ms, with the majority of responses exhibiting peaks in the range of 26 to 30 ms. Generally, the configuration of the EMLRs closely resembled the configuration of acoustic MLRs. While in most cases, behavioral thresholds to identical promontory stimulation were slightly lower, EMLR thresholds closely approximated behavioral electrical promontory thresholds. The EMLR thresholds correlated positively with implanted thresholds and exhibited a negative correlation with implanted dynamic current ranges.
Three cases of primary adenocarcinoma of the temporal bone which simulated a glomus jugulare tumor (on the basis of a thorough preoperative evaluation) are detailed. In each case, a vascular mass was seen beneath an intact tympanic membrane and angiography revealed the presence of a highly vascular mass centered on the jugular bulb. Computed tomography revealed erosive changes within the jugular fossa that were characteristic of a glomus jugulare tumor; in two cases, a significant posterior fossa extension was documented. The intraoperative findings failed to suggest a lesion different from paraganglioma in two of the cases; in the remaining case, the erosion of both bone and dura was diffuse and more suggestive of a malignant neoplasm. A discussion of the clinical behavior of adenocarcinomas of the middle ear is included in order to emphasize the importance of differentiating these lesions preoperatively from the more commonly encountered paragangliomas.