Prevalence of SDHB, SDHC, and SDHD germline mutations in clinic patients with head and neck paragangliomas.

BACKGROUND: Paragangliomas are rare and highly heritable tumours of neuroectodermal origin that often develop in the head and neck region. Germline mutations in the mitochondrial complex II genes, SDHB, SDHC, and SDHD, cause hereditary paraganglioma (PGL). METHODS: We assessed the frequency of SDHB, SDHC, and SDHD gene mutations by PCR amplification and sequencing in a set of head and neck paraganglioma patients who were previously managed in two otolaryngology clinics in the USA. RESULTS: Fifty-five subjects were grouped into 10 families and 37 non-familial cases. Five of the non-familial cases had multiple tumours. Germline SDHD mutations were identified in five of 10 (50%) familial and two of 37 ( approximately 5%) non-familial cases. R38X, P81L, H102L, Q109X, and L128fsX134 mutations were identified in the familial cases and P81L was identified in the non-familial cases. Both non-familial cases had multiple tumours. P81L and R38X mutations have previously been reported in other PGL families and P81L was suggested as a founder mutation. Allelic analyses of different chromosomes carrying these mutations did not show common disease haplotypes, strongly suggesting that R38X and P81L are potentially recurrent mutations. Germline SDHB mutations were identified in two of 10 (20%) familial and one of 33 ( approximately 3%) non-familial cases. P131R and M71fsX80 were identified in the familial cases and Q59X was identified in the one non-familial case. The non-familial case had a solitary tumour. No mutations could be identified in the SDHC gene in the remaining four families and 20 sporadic cases. CONCLUSIONS: Mutations in SDHD are the leading cause of head and neck paragangliomas in this clinic patient series. SDHD and SDHB mutations account for 70% of familial cases and approximately 8% of non-familial cases. These results also suggest that the commonness of the SDHD P81L mutation in North America is the result of both a founder effect and recurrent mutations.

Intraoperative auditory assessments as predictors of hearing preservation after vestibular schwannoma surgery.

The purpose of this study was to determine the association of intraoperative auditory brainstem responses (ABRs) and near-field cochlear nerve action potentials (CNAPs) with postoperative hearing preservation in acoustic tumor surgery. Thirty-three consecutive patients undergoing middle fossa surgery had intraoperative surface ABR and direct CNAP assessments. Postoperatively, hearing was assessed. Hearing preservation was defined as any measurable hearing at any frequency and also by the American Academy of Otolaryngology--Head and Neck Surgery (AAO-HNS) hearing preservation classification system. The presence of an ABR or CNAP was associated with hearing preservation and the absence of an ABR, and CNAP was associated with no hearing preservation in 75.6 percent of the cases. The presence of either the ABR or CNAP was not related to AAO-HNS class outcome. ABR and CNAP had a useful rate of prediction of hearing preservation surgery outcome. However, in nearly one-quarter of the cases, no association between ABR or CNAP responses and hearing preservation was found. This finding must be taken into account when determining the clinical usefulness of these techniques.

Hearing preservation in patients with vestibular schwannomas with sudden sensorineural hearing loss.

OBJECTIVE: We evaluated hearing outcomes in patients with sudden hearing loss and vestibular schwannoma who underwent a hearing preservation operation for tumor resection in an effort to determine whether a history of sudden sensorineural hearing loss has an impact on subsequent hearing preservation surgery. METHODS: Retrospective chart review of 45 patients operated between 1990 and 1998. Patients were divided into "Recovery" (n = 22) and "No Recovery" (n = 23) groups based on preoperative hearing recovery. Hearing preservation was assessed using the AAO-HNS hearing classification system. RESULTS: Measurable hearing was preserved in 73% of patients, with 47% having good postoperative hearing (AAO-HNS Classes A-B). There was no significant difference in hearing outcome from patients presenting with progressive hearing loss (45% Classes A-B). There was also no difference in postoperative hearing between the "Recovery" and "No Recovery" groups. CONCLUSIONS: Patients with sudden hearing loss and vestibular schwannoma have the same chance of hearing preservation after tumor removal as those with progressive loss. Preoperative recovery of hearing is not predictive of hearing preservation. Available data support the nerve compression theory as the mechanism of sudden hearing loss in patients with vestibular schwannoma.

Microvascular decompression of the vestibulocochlear nerve for disabling positional vertigo: the House Ear Clinic experience.

OBJECTIVE: To review characteristics of and outcome in patients undergoing microvascular decompression of the vestibulocochlear nerve. Patients studied had a diagnosis of disabling positional vertigo caused by a vascular loop compressing the VIIIth cranial nerve. STUDY DESIGN: Retrospective chart review and telephone interview. SETTING: Private practice tertiary neurotologic referral center. PATIENTS: Twenty patients with disabling positional vertigo underwent 25 retrosigmoid craniotomies for microvascular decompression between November 1990 and June 1999. The 4 men and 16 women ranged in age from 30 to 71 years (mean age, 46 yr). MAIN OUTCOME MEASURES: Charts were reviewed and patients were contacted by telephone and asked to rate severity of symptoms (tinnitus and dizziness) on a 4-point scale (none = 1, mild = 2, moderate = 3, and severe = 4) before and after surgery. They were also asked to rate their overall disability from their symptoms on the six-point scale established by the American Academy of Otolaryngology-Head and Neck Surgery. Preoperative and postoperative four-frequency (500 Hz, 1 kHz, 2 kHz, and 4 kHz) pure-tone average and speech discrimination scores were calculated and compared. Complications of surgery are also reported. RESULTS: Postoperative tinnitus score and dizziness score showed significant improvement from preoperative scores (p < or = 0.047 and p < or = 0.001, respectively), with 80% of patients improved in dizziness rating; 85% improved in their overall disability rating, and the difference from preoperative to postoperative was significant (p < or = 0.001). The mean postoperative pure-tone averages (15.4 dB) and speech discrimination scores (99%) did not differ from preoperative scores (11.9 dB and 98%). One patient lost all vestibular function in the operated ear (hearing remained intact) as the only complication of surgery. When asked, 83% of patients responded that they would have the surgery again. CONCLUSIONS: Diagnosing disabling positional vertigo secondary to vascular compression of the VIIIth cranial nerve remains the clinical challenge; a clear history plus air-contrast computed tomographic or magnetic resonance imaging make the diagnosis. Microvascular decompression of the vestibulocochlear nerve is a safe and effective operation for these carefully selected patients.

Jacobson's nerve schwannoma: a rare middle ear mass.

The case of a 55-year-old woman with a middle ear mass is presented. The preoperative diagnostic workup, including an audiogram and imaging studies, and the histopathologic findings of the tumor are reviewed. The tumor, a schwannoma, arose from Jacobson's nerve in the middle ear. The surgical anatomy of Jacobson's nerve and the surgical approach to this tumor and to other tumors of the middle ear space are discussed. Tumors of the tympanic cavity are rare, with the exception of cholesteatoma; otherwise, the most common among them are paraganglioma and facial nerve neuroma. This report represents the first documented case of a schannoma arising from Jacobson's nerve in the tympanic cavity.

Early proactive management of vestibular schwannomas in neurofibromatosis type 2.

OBJECTIVE: The treatment of patients with neurofibromatosis Type 2 has always been challenging for neurosurgeons and neurotologists. Guidelines for appropriate management of this devastating disease are controversial. METHODS: A retrospective study of 28 patients with neurofibromatosis Type 2 who underwent 40 middle fossa craniotomies for excision of their acoustic tumors is reported. Eleven patients underwent bilateral procedures. The study focused on hearing preservation and facial nerve results for this group of patients. The 16 male patients and 12 female patients ranged in age (at the time of surgery) from 10 to 70 years, with a mean age of 22.6 years. The mean tumor size was 1.1 cm (range, 0.5-3.2 cm), and the majority of tumors were less than 1.5 cm. RESULTS: Measurable hearing was preserved in 28 ears (70%), with 42.5% being within 15 dB pure-tone average and 15% speech discrimination score of preoperative levels. In 55% of cases there was no change in the hearing class, as defined by the American Academy of Otolaryngology-Head and Neck Surgery. Of the 11 patients who underwent bilateral operations, 9 (82%) retained some hearing bilaterally. After 1-year follow-up periods (mean, 12.8 mo), 87.5% of patients exhibited normal facial nerve function (House-Brackmann Grade I). CONCLUSION: Early surgical intervention to treat acoustic tumors among patients with neurofibromatosis Type 2 is a feasible treatment strategy, with high rates of hearing and facial nerve function preservation.

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.

Proportion of heritable paraganglioma cases and associated clinical characteristics.

OBJECTIVE/HYPOTHESIS: To determine the heritable proportion of paraganglioma (PGL) and identify clinical features associated with heritable PGL. STUDY DESIGN: Patients diagnosed with head and neck PGLs, identified retrospectively through clinical otolaryngology practices and/or participation in previous PGL research studies, were given a medical and family history questionnaire. METHODS: Questionnaire information was used to classify participants as having "heritable" or "non-heritable" cases of PGL. Classification of the participants identified through otolaryngology clinics was used to estimate the heritable proportion of PGL. Statistical analysis was performed to identify significant differences in the clinical characteristics of the heritable versus non-heritable groups. RESULTS: Among the otolaryngology clinic population, 35% were classified as having heritable PGL. Individuals with heritable PGL were younger on average than those with non-heritable PGL. The majority of non-heritable participants were female, but there was an equal gender ratio among the heritable participants. Individuals diagnosed with a carotid body tumor (CBT) were 5.8 times more likely to be classified as heritable than those diagnosed with PGL at other anatomic locations. CONCLUSIONS: Approximately 35% of individuals who present to an otolaryngologist with a head and neck PGL have inherited a predisposition for this growth. Among individuals diagnosed with head and neck PGL, those diagnosed with CBT are 5.8 times more likely to have an inherited predisposition than those diagnosed with PGL at other anatomic locations.

Complications of venous insufficiency after neurotologic-skull base surgery.

OBJECTIVE: To characterize the incidence and complications resulting from venous insufficiency after neurotologic-skull base surgery. STUDY DESIGN: Retrospective case review of >3,500 cases. SETTING: Tertiary referral center, inpatient surgery. PATIENTS: Six patients: four with complications related to chronic venous insufficiency and two with complications related to acute venous insufficiency. INTERVENTION(S): Medical (steroids, acetazolamide, hyperventilation, mannitol) and surgical (lumboperitoneal shunt, optic nerve decompression, embolectomy) interventions were undertaken. MAIN OUTCOME MEASURE(S): Chronic venous insufficiency: nonobstructive hydrocephalus manifested by headache, disequilibrium, and papilledema with resultant visual loss. Acute venous insufficiency: acute nonobstructive hydrocephalus resulting in mental status abnormalities in the postoperative period. CONCLUSIONS: (1) Incidence of 1.5 per 1,000 cases. (2) Acute and chronic forms with different pathogenesis. (3) Acute form presents postoperatively with change in consciousness and herniation, and may proceed to death. (4) Chronic form presents months or years postoperatively with headache, disequilibrium, and visual changes from papilledema. (5) Occurs almost solely in patients with preoperative abnormalities of the venous collecting system. (6) Causes mental status changes postoperatively.

Jacobson's nerve schwannoma presenting as middle ear mass.

Schwannoma is one of the common benign middle ear space tumors. Middle ear space schwannomas may originate from the nerves of the tympanic cavity or by extensions from outside the middle ear space. In the English-language literature, the facial nerve and chorda tympani nerve, but not yet the tympanic branch of glossopharyngeal nerve (Jacobson's nerve), have been reported as the origins of intrinsic middle ear space schwannomas. We present the clinical and radiologic features of a middle-space schwannoma originating from Jacobson's nerve, and suggest that such a tumor be included in the differential diagnosis of middle ear tumors.

Lesions of the internal auditory canal and cerebellopontine angle in an only hearing ear: is surgery ever advisable?

OBJECTIVE: To define the indications for surgery in lesions of the internal auditory canal (IAC) and cerebellopontine angle (CPA) in an only hearing ear. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: Seven patients with lesions of the IAC and CPA who were deaf on the side opposite the lesion. Five patients had vestibular schwannoma (VS), and one each had meningioma and progressive osseous stenosis of the IAC, respectively. The opposite ear was deaf from three different causes: VS (neurofibromatosis type 2 [NF2]), sudden sensorineural hearing loss, idiopathic IAC stenosis. INTERVENTION(S): Middle fossa removal of VS in five, retrosigmoid resection of meningioma in one, and middle fossa IAC osseous decompression in one. MAIN OUTCOME MEASURE: Hearing as measured on pure-tone and speech audiometry. RESULTS: Preoperative hearing was class A in four patients, class B in two, and class C in one. Postoperative hearing was class A in three patients, class B in one, class C in two, and class D in one. CONCLUSIONS: Although the vast majority of neurotologic lesions in an only hearing ear are best managed nonoperatively, in highly selected cases surgical intervention is warranted. Surgical intervention should be considered when one or more of the following circumstances is present: (1) predicted natural history of the disease is relatively rapid loss of the remaining hearing, (2) substantial brainstem compression has evolved (e.g., large acoustic neuroma), and/or (3) operative intervention may result in improvement of hearing or carries relatively low risk of hearing loss (e.g., CPA meningioma).

Prognostic factors for hearing preservation in vestibular schwannoma surgery.

OBJECTIVE: To determine whether prognostic indicators for hearing preservation could be identified in patients with vestibular schwannoma undergoing middle fossa craniotomy resection. STUDY DESIGN: Prospective case review. SETTING: Private practice tertiary referral center. PATIENTS: 333 patients with serviceable hearing and vestibular schwannoma resected by middle fossa craniotomy from 1992 to 1998. MAIN OUTCOME MEASURES: Potential prognostic indicators, including tumor size and nerve of origin, preoperative pure-tone average, speech discrimination, distortion product otoacoustic emission testing, age, auditory brainstem response (ABR), and electronystagmography. RESULTS: Postoperative hearing near preoperative levels was attained in 167 patients (50%), with an American Academy of Otolaryngology-Head and Neck Surgery Class A hearing result in 33% and a Class B result in 26%. Comparison of potential prognostic indicators between groups with hearing preserved and the group with no measurable hearing revealed significant differences in preoperative hearing, ABR, and tumor origin data. Better preoperative hearing, shorter intraaural wave V latency, shorter absolute wave V latency, and superior vestibular nerve origin were associated with higher rates of hearing preservation. CONCLUSIONS: Preoperative hearing status, ABR, and intraoperative tumor origin data were shown to be of value as prognostic indicators.

Cerebrospinal fluid otorrhea through a congenitally patent fallopian canal.

Cerebrospinal fluid (CSF) otorrhea is a relatively rare entity that may occur either as a spontaneous occurrence or as a result of trauma or surgery. Spontaneous CSF leaks may be found during tympanocentesis, myringotomy, or tube insertion for chronic middle ear effusion. Rapid identification of the problem and timely treatment are required to avoid life-threatening complications such as meningitis. The site of leakage must also be identified so that the disorder can be treated effectively. Computed tomography, magnetic resonance imaging, and radionucleotide localization scanning all play a role in the early identification of the leakage site. A detailed knowledge of possible CSF leakage pathways aids in evaluating imaging studies. We report 2 rare cases of CSF otorrhea through a congenitally patent facial canal and their management.

Conservative facial nerve management in jugular foramen schwannomas.

OBJECTIVE: Although transposition of the facial nerve is crucial in infiltrative vascular lesions involving the jugular foramen, the objective was to show that a conservative approach to management of the facial nerve is sufficient with jugular foramen neuromas because of their noninfiltrative, less vascular nature and medial location in the jugular foramen. STUDY DESIGN: Retrospective case review. SETTING: Tertiary, private, multiphysician, otologic practice. PATIENTS: Sixteen patients with jugular foramen schwannoma (18 procedures) treated between January 1975 and October 1995. The 8 male and 8 female patients ranged in age from 13 to 66 years (mean age 47.7 years). INTERVENTION: One-stage, total jugular foramen neuroma removal without transposition of the facial nerve, using a variety of surgical approaches. MAIN OUTCOME MEASURES: Facial nerve transposition (yes or no), House-Brackmann facial nerve grade, lower cranial nerve status, complications. RESULTS: One-stage total tumor removal was accomplished in all the cases. In 13 (72%) of the neuromas, removal was accomplished without facial nerve transposition. Transposition was performed in 2 revision cases in which scar tissue from a previous operation prevented complete control of the carotid artery and safe removal, 2 cases with large tumor extension anteriorly to the petrous apex, and 1 case with extensive involvement of the middle ear. A House-Brackmann facial nerve Grade I or II was obtained in 16 of the 18 procedures, with 1 Grade III and 1 case that remained Grade V, as it was preoperatively. CONCLUSIONS: One-stage, total tumor removal can be achieved with excellent control of the important vascular structures and without transposition of the facial nerve in a majority of jugular foramen schwannomas.

Coexpression of neurotrophic growth factors and their receptors in human facial motor neurons.

Neuronal development and maintenance of facial motor neurons is believed to be regulated by neurotrophic growth factors. Using celloidin-embedded sections, we evaluated immunoreactivity of 11 neurotrophic factors and their receptors in facial nuclei of human brain stems (4 normal cases, and 1 from a patient with facial palsy and synkinesis). In the normal subjects, positive immunoreactivity of the growth factor neurotrophin-4 and acidic fibroblast growth factor (aFGF) was observed in facial motor neurons, as was positive immunoreactivity against ret, the receptor shared by glial cell line-derived neurotrophic factor and neurturin. Immunoreactivity was moderate for the receptor trkB and strong for trkC. In the case of partial facial palsy, surviving cells failed to show immunoreactivity against neurotrophins. However, immunoreactivity of aFGF was up-regulated in both neuronal and non-neuronal cells in this patient. Results suggest that these trophic growth factors and their receptors may protect facial neurons from secondary degeneration and promote regrowth of the facial nerve after axotomy or injury.

Acoustic tumor growth: implications for treatment choices.

BACKGROUND: Knowledge of acoustic neuroma (AN) growth is essential for treatment planning. METHODS: A retrospective analysis of 119 patients with AN (mean age, 65 years; range, 37-84 years) followed with interval magnetic resonance imagings (MRIs) was performed. Change in maximum tumor dimension as a function of follow-up period was analyzed. RESULTS: Overall, maximum tumor dimension increased >2 mm in only 30% of patients. Of those that grew, the mean growth rate was 3.8 mm/year (maximum, 25 mm/year). Age, gender, and laterality did not predict growth. Most tumors that grew (86.1 %) were <20 mm at presentation. However, tumors >20 mm were statistically more likely to grow (71%, p =0.028). CONCLUSIONS: Most ANs followed with periodic MRIs do not grow. Available clinical information usually cannot predict growth. Serial MRIs are advocated for all patients treated with observation.

Intraoperative corticosteroids in acoustic tumor surgery.

BACKGROUND: Corticosteroids are frequently used for the prevention and treatment of neural edema. Although perioperative steroid therapy has been used in patients undergoing acoustic neuroma removal, the efficacy of such therapy has not been previously documented. METHODS: A retrospective review of 169 patients who underwent acoustic neuroma surgery with (n = 75) or without (n = 94) a single dose of intraoperative corticosteroids was performed. Tumor size ranged from 0.4 cm to 6 cm (mean, 2.1; SD, 1.0) The translabyrinthine approach was used in 85% of the patients, and the middle cranial fossa approach was used in 13%. Data were analyzed for differences in postoperative facial function and complication rates. RESULTS: After controlling for differences in tumor size, no significant effects of steroid therapy were found for any of the outcome variables. CONCLUSIONS: This retrospective study showed no apparent benefit from intraoperative steroid use in acoustic neuroma surgery. A prospective, randomized, placebo-controlled trial should be performed to confirm these findings.

Report of 190 consecutive cases of large acoustic tumors (vestibular schwannoma) removed via the translabyrinthine approach.

OBJECT: The choice of approach for surgical removal of large acoustic neuromas is still controversial. The authors reviewed the results in a series of patients who underwent removal of large tumors via the translabyrinthine approach. METHODS: The authors conducted a database analysis of 190 patients (89 men and 101 women) with acoustic neuromas 3 cm or greater in size. The mean age of these patients was 46.1+/-15.6 years. One hundred seventy-eight patients underwent primary translabyrinthine surgical removal and 12 underwent surgery for residual tumor. Total tumor removal was accomplished in 183 cases (96.3%). The tumor was adherent to the facial nerve to some degree in 64% of the cases, but the facial nerve was preserved anatomically in 178 (93.7%) of the patients. Divided nerves were repaired by primary attachment or cable graft. Facial nerve function was assessed immediately after surgery, at the time of discharge, and at 3 to 4 weeks and 1 year after discharge. Excellent function (House-Brackmann facial nerve Grade I or II) was present in 55%, 33.9%, 38.8%, and 52.6% of the patients for each time interval, respectively, with acceptable function (Grades I-IV) in 81% at 1 year. Cerebrospinal fluid leakage that required surgical repair occurred in only 1.1% of the patients and meningitis in 3.7%. There were no deaths. CONCLUSIONS: Use of the translabyrinthine approach for removal of large tumors resulted in good anatomical and functional preservation of the facial nerve, with minimum incidence of morbidity and no incidence of mortality. The authors continue to recommend use of this approach for acoustic tumors larger than 3 cm and for smaller tumors when hearing preservation is not an issue.