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Biomedical subjects

S G Harner

Publications and source records attributed to S G Harner.

At least 19 recordsLinked to original sources
PubMed1995

Stereotactic radiosurgery using the gamma knife for acoustic neuromas.

PURPOSE: To assess the efficacy and toxicity of stereotactic radiosurgery using the gamma knife for acoustic neuromas. METHODS AND MATERIALS: Between January 1990 and January 1993, 36 patients with acoustic neuromas were treated with stereotactic radiosurgery using the gamma knife. The median maximum tumor diameter was 21 mm (range: 6-32 mm). Tumor volumes encompassed within the prescribed isodose line varied from 266 to 8,667 mm3 (median: 3,135 mm3). Tumors < or = 20 mm in maximum diameter received a dose of 20 Gy to the margin, tumors between 21 and 30 mm received 18 Gy, and tumors > 30 mm received 16 Gy. The dose was prescribed to the 50% isodose line in 31 patients and to the 45%, 55%, 60%, 70%, and 80% isodose line in one patient each. The median number of isocenters per tumor was 5 (range: 1-12). RESULTS: At a median follow-up of 16 months (range: 2.5-36 months), all patients were alive. Thirty-five patients had follow-up imaging studies. Nine tumors (26%) were smaller, and 26 tumors (74%) were unchanged. No tumor had progressed. The 1- and 2-year actuarial incidences of facial neuropathy were 52.2% and 66.5%, respectively. The 1- and 2-year actuarial incidences of trigeminal neuropathy were 33.7% and 58.9%, respectively. The 1- and 2-year actuarial incidence of facial or trigeminal neuropathy (or both) was 60.8% and 81.7%, respectively. Multivariate analysis revealed that the following were associated with the time of onset or worsening of facial weakness or trigeminal neuropathy: (a) patients < age 65 years, (b) dose to the tumor margin, (c) maximum tumor diameter > or = 21 mm, (d) use of the 18 mm collimator, and (e) use of > five isocenters. The 1- and 2-year actuarial rates of preservation of useful hearing (Gardner-Robertson class I or II) were 100% and 41.7% +/- 17.3, respectively. CONCLUSION: Stereotactic radiosurgery using the gamma knife provides short-term control of acoustic neuromas when a dose of 16 to 20 Gy to the tumor margin is used. Preservation of useful hearing can be accomplished in a significant proportion of patients.

Adult↗
PubMed1995

Impact of cranioplasty on headache after acoustic neuroma removal.

We reported previously the incidence of headache after the retrosigmoid removal of an acoustic neuroma as 23% at 3 months, declining to 9% at 2 years after surgery. In an attempt to reduce the incidence and the severity of these headaches, we made one change in our surgical procedure, which was to perform a cranioplasty with methyl methacrylate. Twenty-four patients underwent the cranioplasty and were followed for at least 3 months postoperatively. These patients were matched to 24 patients who did not undergo a cranioplasty. We found a 4% incidence of headache in the cranioplasty group and a 17% incidence in the matched group. No complications were related to this change in our procedure.

Adult↗
PubMed1993

Middle ear adenoma and adenocarcinoma.

Adenomas and adenocarcinomas originating from the middle ear are few in number and have met with significant controversy in the literature. Our experience with 11 previously described patients is updated and five new cases are added. These tumors were seen in persons whose ages ranged from 7 to 77 years. The most common initial symptom was decreased hearing (11 cases), followed by otorrhea (4 cases), and otalgia (4 cases). At the time of diagnosis, facial nerve weakness was present in several patients (seven), and this was a poor prognostic sign. These glandular tumors engender controversy regarding histologic origin and the pathologic demarcation between adenoma and adenocarcinoma. In this review, we show that otorrhea, bone erosion, facial nerve involvement, and aggressive clinical behavior can be the result of lesions that appear microscopically benign. Furthermore, we present evidence of the similarity of these glandular lesions to paragangliomas and carcinoid tumors. Finally, pathologic data are presented to develop the previously unreported theory that the origin for this group of tumors is paraganglionic tissue.

Adenocarcinoma↗
PubMed1993

Headache after acoustic neuroma excision.

The retrosigmoid approach to acoustic neuroma removal has recently been criticized for causing frequent and severe headache postoperatively. We review 331 patients who had acoustic neuroma removal by the retrosigmoid approach at one institution. The incidence of postoperative headache was 23 percent at 3 months, 16 percent at 1 year, and 9 percent at 2 years. Management was primarily with analgesics, physiotherapy, and reassurance. No patient had additional surgical treatment. Information available indicates that the incidence of postoperative headache associated with the translabyrinthine approach is similar to that of the retrosigmoid approach. Perhaps filling the craniectomy defect will decrease further the incidence of headache postoperatively.

Facial Nerve↗
PubMed1993

Acoustic neuroma and pregnancy.

From January 1978 through July 1989, 360 patients underwent primary removal of an acoustic neuroma at the Mayo Clinic. Seventy of these patients were women under the age of 46 years; six of them were pregnant between the time of onset of their symptoms and the removal of their tumor. A review of the records of these six women revealed the presenting complaint in most to be central neurologic symptoms rather than labyrinthine symptoms. All had unilateral tumors. These tumors tended to be larger and more vascular than those in the nonpregnant cohort, and to have greater surgical morbidity. The pure-tone hearing levels were normal in four of these patients. All women experienced normal vaginal delivery without complication. Based on our experience with these women, we believe that acoustic neuroma present during pregnancy may be managed by close observation until the postpartum period, provided there are no impending neurologic complications.

Adolescent↗
PubMed1993

Does the distribution of Schwann cells correlate with the observed occurrence of acoustic neuromas? .

Acoustic neuromas account for 75 to 80 percent of cerebellopontine angle tumors and 8 to 10 percent of all intracranial neoplasms. These tumors arise from the Schwann cell sheath that surrounds the peripheral portion of the facial, cochlear, superior, and inferior vestibular nerves. Theoretically, a schwannoma may arise from Schwann cells anywhere along these nerves from the glial-Schwann cell junction to the end organ. Clinically, however, they most frequently originate from the vestibular nerves, occasionally from the facial, and only rarely from the cochlear nerve. This investigation utilized light microscopy, immunochemistry, and digital optical morphologic analysis to determine the distribution of Schwann cells along the facial and vestibulocochlear nerves in an attempt to explain the observed distribution of tumors, and to evaluate currently accepted theories. No direct correlation between the distribution of Schwann cells and the observed distribution of schwannomas was found. Thus, this study did not confirm the currently held theories regarding schwannoma distribution in these nerves.

Cell Count↗
PubMed1992

Effect of BAEP monitoring on hearing preservation during acoustic neuroma resection.

We measured the effect of brainstem auditory evoked potential (BAEP) monitoring on hearing preservation in acoustic neuroma resection in 90 consecutive patients with monitoring compared with 90 historical controls matched for tumor size and preoperative hearing status. In small tumors (less than 2 cm), BAEP monitoring was associated with a higher rate of hearing preservation and a greater chance that the hearing preserved was clinically useful. Changes in the BAEP intraoperatively showed a good correlation with postoperative hearing status.

Evoked Potentials, Auditory, Brain Stem↗
PubMed1992

Current results of the retrosigmoid approach to acoustic neurinoma.

Since 1984 when cranial nerve monitoring became routinely performed at the Mayo Clinic, 255 patients have undergone 256 procedures using the retrosigmoid approach for the removal of acoustic neurinomas. Of these, 221 patients had some hearing before surgery and 52 maintained hearing following surgery. The anatomical continuity of the facial nerve was preserved in 237 of these 256 procedures. It was possible to perform a primary end-to-end anastomosis in seven of the remaining 19 patients, and one patient had a cable graft inserted. Thus, 95.7% of these patients were believed to have potential for spontaneous facial nerve function. Of the 11 patients in whom this was not possible, seven underwent early spinal accessory facial anastomosis, in two hypoglossal-facial anastomosis was performed, and two had no facial nerve procedures and have paralysis of the facial nerve. There were two deaths from a pulmonary embolus in the early postoperative period, both 4 days following otherwise uneventful surgery. The most common postoperative complication was cerebrospinal fluid leakage, which has not resulted in significant permanent morbidity although early repair for this problem is now routinely recommended. Other complications were quite rare and have generally not resulted in any major change in patient lifestyle or activity level. This review reconfirms that the retrosigmoid surgical treatment of acoustic tumors continues to be an acceptable treatment option.

Adolescent↗
PubMed1991

Auditory monitoring during acoustic neuroma removal.

Preservation of hearing has become attainable for patients with small acoustic neuromas. Brain-stem auditory evoked response was monitored intraoperatively in 60 patients undergoing acoustic neuroma surgery via the posterior fossa approach. The overall rate of hearing preservation was 30% in the monitored group and 20% in 60 patients who were matched for tumor size and preoperative hearing level and underwent the same surgical procedure but without intraoperative brain-stem auditory evoked response monitoring. The rate of hearing preservation was correlated with tumor size: with tumors less than or equal to 1 cm, hearing was preserved in 82% of monitored and 36% of unmonitored patients; hearing was not preserved with tumors larger than 3 cm. Intraoperative brain-stem auditory evoked response monitoring appears to have improved the preservation of hearing during removal of small tumors.

Adolescent↗
PubMed1991

Longitudinal followup of patients with Menière's disease.

The etiology, pathophysiology, and natural history of Menière's syndrome are poorly understood. The reported studies have had inadequate followup or insufficient numbers of patients to allow conclusions about the natural history. Our study group was 119 patients who had the classic symptom complex of episodic vertigo, tinnitus, and hearing loss in the year 1970. After initial review of these charts, follow-up information was obtained by questionnaire, telephone interview, chart review, or repeat examination, when possible, both in 1983 and in 1988, for a total followup of 18 years. In the patients with followups of at least 14 years, vertiginous episodes had disappeared completely in 50% of patients and somewhat resolved in 28%; hearing was absent in 48% and worse in 21%. Surprisingly, 43% of patients underwent surgery at some point for control of vertigo. Bilateral disease was present initially in 13% and developed subsequently in 45% of patients. Other areas reviewed included the efficacy of long-term medical treatment, frequency and severity of vertiginous attacks, and contralateral ear symptoms.

Adult↗
PubMed1990

Preoperative and postoperative auditory brain-stem response results for patients with eighth-nerve tumors.

Preoperative and postoperative auditory brain-stem response results and audiologic data were reviewed for seven patients whose hearing was preserved after eighth-nerve tumor surgery. Auditory brain-stem response absolute latencies (I, III, and V) and interpeak intervals (I-III, III-V, and I-V) were identified more often postoperatively than preoperatively. Even though postoperative absolute latencies were usually abnormal, the interpeak intervals were usually normal following surgery. Postoperative hearing sensitivity was unchanged or slightly poorer for five of the seven patients, but postoperative speech discrimination was the same or better for six of the seven patients. All three patients having acoustic reflex testing showed improvement postoperatively.

Adult↗
PubMed1990

Retrosigmoid removal of acoustic neuroma: experience 1978-1988.

The need to preserve hearing during acoustic neuroma removal has rekindled interest in labyrinth-sparing procedures. This review of 11 years' experience with the retrosigmoid approach to acoustic neuroma removal includes 335 procedures in 332 patients. There were no intraoperative deaths; two patients died in the postoperative period. The facial nerve was preserved in 86.3% of procedures, and auditory function was preserved in 45 procedures (34% of those tumors were 2 cm or smaller). Postoperative complications occurred in 101 procedures, the most common being cerebrospinal fluid otorhinorrhea in 40 cases; 25 of these required secondary surgery. Meningitis occurred 16 times and aspiration 8 times; all other complications were less frequent. Tumor removal was incomplete in eight procedures; in only one of these cases has tumor recurred. The six recurrences usually were identified 5 or more years postoperatively. This has prompted us to follow patients for 7 years postoperatively. Major changes in our management include the use of the supine position and of electrophysiologic monitoring. Advantages of the approach are: (1) wide access to the tumor, (2) applicability to all tumor sizes, (3) potential to preserve facial and auditory function in all cases, and (4) ability to change procedure without sacrificing labyrinth. This review confirms our confidence in this approach to acoustic neuroma removal.

Adolescent↗
PubMed1990

[Auditory brainstem response in the aged and elderly].

Auditory brainstem response(ABR) was studied in 63 old healthy individuals (mean age = 66.42 +/- 9.88 years). They presented some degree of hearing loss (pure tone hearing threshold for 4 frequencies less than or equal to 30dB HL). Meanwhile 24 younger subjects (half for each sex, mean age = 17.61 +/- 2.63 years) with normal hearing were chosen as the control group. It was found that (a) the older group had greater mean values for both absolute peak latencies and inter-peak latencies than the younger group. The results indicate that age-related hearing loss is due to cochlear pathology but do not exclude the possibility of central auditory involvement. (b) the main parameters of ABR in both ears for each individual were quite symmetric. This fact implicates the diagnostic significance in differentiating presbycusis and space occupying lesion in the brainstem. (c) sex also affected the ABR in both age groups. Males were easier to be affected than females.

Aged↗
PubMed1988

Mast cell pharyngitis as a cause of supraglottic edema.

A 30-year-old nonatopic woman had experienced a 9-year history of persistent symptoms of supraglottic edema. She had previously undergone epiglottectomy and excision of redundant left arytenoid tissue to improve her breathing and dysphagia. Uvular tissue was removed surgically at our clinic for histopathological examination of the excised tissues. This revealed diffuse infiltration by mast cells, many of which appeared degranulated. Uvular tissue from control patients undergoing uvulopalatopharyngoplasty for obstructive sleep apnea contained significantly fewer mast cells per high power field. To our knowledge such a degree of mast cell infiltration into supraglottic tissues has not been reported previously or associated with clinical symptoms.

Adult↗
PubMed1988

The effect of fibrin tissue adhesive on the middle and inner ears of chinchillas.

The purpose of this study was to examine potential toxic effects of fibrin tissue adhesive to the middle and inner ears. Using the chinchilla as our experimental model, we placed fibrin sealant on either the footplate or the round window membrane in one ear, and placed similar amounts of normal saline in the same area of the opposite ear. In addition, the fibrin adhesive was used to anchor a fascia lata graft for myringoplasty. Both fibrin adhesive and normal saline produced mild reactions in the middle and inner ears when they were placed on the round window membrane; little reaction occurred when fibrin adhesive was placed on the oval window or when it was used for myringoplasty.

Animals↗
PubMed1988

Intraoperative monitoring of the facial nerve.

Anatomic preservation of the facial nerve, with maximal facial function, is one of the goals of acoustic neuroma surgery. Application of electrophysiologic monitoring techniques is useful in achieving this goal. Preoperative electromyography and nerve conduction studies provide important prognostic information for preservation of the nerve and postoperative function. Intraoperative electromyography alerts the surgeon to facial nerve proximity and potential injury. Direct nerve stimulation is utilized to confirm the location and integrity of the nerve. Matched-pair analysis of two groups of patients demonstrated an increased ability to preserve the facial nerve with less postoperative facial deformity.

Adolescent↗
PubMed1987

Improved preservation of facial nerve function with use of electrical monitoring during removal of acoustic neuromas.

Continuous spontaneous electromyographic activity and responses to electrical stimulation of the facial nerve in the surgical field were monitored in 48 patients undergoing primary removal of an acoustic neuroma. The operative and postoperative results in these patients were compared with the results in 48 patients who were matched for age and size of tumor and who underwent the same surgical procedure without intraoperative monitoring. Eighty-three percent of the patients had preoperative evidence of facial neuropathy, which was more severe with larger tumors. Postoperative facial nerve function was most accurately predicted on the basis of the extent of facial neuropathy on preoperative electrophysiologic testing. Anatomic preservation of the facial nerve in patients with large tumors was substantially improved in the monitored patients (67%) in comparison with those without monitoring (33%). No difference was noted in facial nerve function in the two groups of patients immediately postoperatively. By 3 months, the degree of improvement in the monitored group exceeded that in those who were not monitored, particularly in patients with medium-sized and large tumors.

Adult↗