Intraoperative monitoring of the vagus nerve during intracranial glossopharyngeal and upper vagal rhizotomy: technical note.

Intracranial section of the glossopharyngeal and upper vagal rootlets for the treatment of vagoglossopharyngeal neuralgia may cause dysphagia or vocal cord paralysis from injury to the motor vagal rootlets in 10% to 20% of cases. To minimize this complication, we recently applied a technique of intraoperative monitoring of the vagus nerve (previously described by Lipton and McCaffery to monitor the recurrent laryngeal nerve during thyroid surgery) in a patient undergoing intracranial rhizotomy for vagoglossopharyngeal neuralgia. By inserting an electrode in the ipsilateral false vocal cord and stimulating the rostral vagal rootlets intraoperatively under general anesthesia, we could differentiate the rostral vagal motor rootlets from the sensory rootlets. In this patient, the technique allowed us to preserve a rostral vagal rootlet, which if sectioned, could have caused dysphagia or vocal cord paralysis. We conclude that intraoperative monitoring of the rostral vagal rootlets is an important technique to minimize complications of upper vagal rhizotomy.

Proximal-to-distal facial amplitude ratios as predictors of facial nerve function after acoustic neuroma excision.

Electrophysiological studies (for example, electroneuronography, nerve action potentials, absolute amplitudes of the muscle compound action potentials, and stimulation thresholds) do not accurately predict facial nerve function after the excision of acoustic neuromas. To eliminate individual nerve variability, the authors measured the ratio of the amplitudes of muscle compound action potentials produced by stimulating the facial nerve at the brainstem proximally and at the internal auditory meatus near the transverse crest distally after total tumor excision in 20 patients. The mean tumor size was 36 mm. The facial nerves were anatomically intact in all patients after tumor excision. The follow-up period ranged from 14 to 28 months. Facial nerve outcome was determined by a modified House-Brackmann grading scale. Initial facial nerve function was measured at Days 4 to 7 postoperatively, and final function was the grade at last follow up. The following results were obtained: all patients with proximal-to-distal amplitude ratios greater than 2:3 had Grade III or better initial function and Grade I final facial nerve function; 90% of patients with amplitude ratios between 1:3 and 2:3 had Grade III or worse initial facial nerve function, and 100% of these patients had Grade III or better final facial nerve function; all patients with amplitude ratios less than 1:3 had Grade IV or worse initial and final facial nerve function. The authors conclude that the proximal-to-distal amplitude ratios after acoustic neuroma excision can accurately predict postoperative facial nerve function.

Hypermobility of the incudostapedial joint: a clinical entity.

During exploratory tympanotomy for conductive deafness, the surgeon is occasionally perplexed to find no apparent cause for the air-bone gap. This unexplained deafness has been called "inner ear conductive hearing less" because of the apparent absence of pathology in the middle ear. The incudostapedial joint was studied in 68 vertically sectioned temporal bones and the anatomy is presented. Varying amounts of laxity is observed in the normal joint capsule at the time of surgery. A theory is suggested in which an elongated capsule allows incus motion without energy transmission to the stapes. It is proposed that hypermobility of the incudostapedial joint may exist and explain conductive hearing loss of undetermined etiology.

Transpetrosal access to meningiomas juxtaposing the temporal bone.

Meningiomas arising from the petroclival dura have presented a challenge to both otolaryngologists and neurosurgeons. Access by means of subtemporal, suboccipital, translabyrinthine, or transcochlear routes have inherent limitations both surgically as well as from resultant morbidity. Since 1988, the authors have used a transpetrosal transtentorial (combined subtemporal suboccipital presigmoid) approach to these lesions in selected cases. The goals of this technique have been to preserve function of the cranial nerves, to avoid excessive retraction of the temporal lobe and cerebellum, and to eliminate damage to the venous sinus and Labbés vein. Exposure of the base of the tumor for ablation of the blood supply and access for tumor removal is an important advantage of this approach.

Neuroaudiologic abnormalities in patients with type 1 neurofibromatosis.

Although the protean manifestations of neurofibromatosis have been studied for many years, much is yet to be learned about this disease in young children. Specifically, little is known about the prevalence and significance of early neurotologic abnormalities in this population. Our review of the recent literature, however, failed to identify any publication on the use of ABR and acoustic reflex testing in the pediatric neurofibromatosis population. This study reports on a standardized differential diagnostic battery conducted on 44 children diagnosed as having neurofibromatosis. Results of the neuroaudiologic battery indicated that 32% of the children had significant abnormalities on ABR and acoustic reflex dynamic tests. This is a substantially higher prevalence of abnormalities than reported by another group at a recent NIH concensus meeting on neurofibromatosis. Discussion of the implications of these findings regarding evaluation protocols, as well as management for this select patient population, will follow.

Lead exposure and the central auditory processing abilities and cognitive development of urban children: the Cincinnati Lead Study cohort at age 5 years.

This analysis examined the relationship between lead exposure as registered in whole blood (PbB) and the central auditory processing abilities and cognitive developmental status of the Cincinnati cohort (N = 259) at age 5 years. Although the effects were small, higher prenatal, neonatal, and postnatal PbB levels were associated with poorer central auditory processing abilities on the Filtered Word Subtest of the SCAN (a screening test for auditory processing disorders). Higher postnatal PbB levels were associated with poorer performance on all cognitive developmental subscales of the Kaufman Assessment Battery for Children (K-ABC). However, following adjustment for measures of the home environment and maternal intelligence, few statistically or near statistically significant associations remained. Our findings are discussed in the context of the related issues of confounding and the detection of weak associations in high risk populations.

Intraoperative experience with neuromotor evoked potentials. A review of 60 consecutive cases.

STUDY DESIGN: A review of 60 surgical cases for correction of scoliosis, during which neuromotor evoked potentials and somatosensory evoked potentials were monitored. OBJECTIVES: To determine the validity and reliability of intraoperative neuromotor evoked potential monitoring in cases of scoliosis, where damage to the motor tracts of the spinal cord can occur. SUMMARY OF BACKGROUND DATA: Recently, the validity of neuromotor evoked potentials monitoring has been challenged, suggesting that the responses are not necessarily neuromotor evoked responses, but a combination of neuromotor and somatosensory evoked responses. This theory rendered the responses a potentially invalid measure of motor ability. However, despite controversy surrounding this topic, many professionals consider neuromotor evoked potential monitoring to be a successful and reliable measure of motor spinal cord function. METHODS: The results of neuromotor evoked potential testing were reviewed in 60 consecutive cases of children who underwent surgery for scoliosis. A standard protocol described in 1995 by Owen was used. RESULTS: Clinically useful neuromotor evoked potentials were obtained for 54 patients (90%). Inability to obtain neuromotor evoked potentials occurred in six patients (10%). CONCLUSIONS: This two-part study demonstrated the efficacy and reliability of neuromotor evoked potential monitoring during scoliosis surgery and examined the sources of difficulty in achieving accurate and valid results.

Effects of occupational exposure to organic solvents and noise on hearing.

This study explored the effects of occupational exposure to solvents and noise on hearing. Interviews and hearing tests were conducted for printing and paint manufacturing workers. The experimental groups included unexposed (N = 50) workers and workers exposed to noise (N = 50), noise and toluene (N = 51), or an organic solvent mixture (N = 39). The risk of hearing loss was greater for the exposed groups than for the unexposed group. The adjusted relative risk estimates were four times greater [95% confidence interval (95% CI) 1.4-12.2] for the noise group, 11 times greater (95% CI 4.1-28.9) for the noise and toluene group, and five times greater (95% CI 1.4-17.5) for the solvent-mixture group. The findings suggest that exposure to the studied solvents had a toxic effect on the auditory system and that an interaction between noise and toluene took place. The audiological results of the noise and toluene group suggest a central auditory pathway involvement in the hearing losses observed.

Prediction of bithermal caloric response from monothermal stimulation.

The use of either cold or warm caloric stimulation alone as a screening tool for unilateral weakness has been suggested as a means of both shortening testing time and reducing patient discomfort. The validity of the monothermal caloric test must be well established before it can be routinely used in clinical situations. The purpose of this investigation was to re-evaluate the monothermal caloric test by examining the correlations between unilateral weakness derived from bithermal caloric stimulation compared to monothermal caloric results using either warm or cool stimulation alone. A retrospective analysis of 200 patients indicated significant correlations between bithermal and monothermal unilateral weakness for patients with unilateral weakness of less than 15% and greater than 30% for both warm and cool water stimulation. For patients with 15% to 30% unilateral weakness, the bithermal and monothermal calorics were significantly correlated for only the cool condition. When predicting normal or greater than 20% unilateral weakness, either of the monothermal calorics have greater than 85% efficiency, with specificity greater than 94% and sensitivity greater than 64%. However, the false-negative rate is 29% for warm and 36% for cool calorics. The high rate of false-negative findings indicates that screening tests have no place in a diagnostic battery, especially in view of the implications for missing significant pathology.

Auditory processing abilities in children with previous middle ear effusion.

The present study was designed to determine whether auditory processing disorders are present in children with documented middle ear effusion (MEE) that required surgical treatment. Children with previous MEE and control subjects, in two age groups, were studied using five tests of auditory processing abilities: low-pass filtered speech, staggered spondaic word test, speech in noise, auditory sequential memory, and sound blending. Results found differences in groups at mean age 7 on the filtered speech tests, but no statistical differences were found on any other test at age 7 or on any test at mean age 9. The results indicate that well-managed MEE appears to have no long-term effects on children acquiring this disease.

Central auditory function.

Central auditory disorders in children and adults have become more widely recognized in patients seen by otolaryngologists and audiologists. This article briefly defines those clinical entities, discusses the historic background of testing, and describes current and future test approaches to assessment of central auditory disorders.

The effects of chronic middle ear effusion on speech and language development -- a descriptive study.

In this study, the speech and language skills of children with histories of chronic middle ear effusion were analyzed. Forty-seven children between the ages of one year eleven months and five years five months were given a battery of speech and language tests in the course of a diagnostic evaluation. All the children had been referred to speech pathology by a physician because of a suspected communication disorder. All subjects had histories of three or more episodes of middle era effusion, with the first episode occurring prior to 18 months of age. All medical records were checked and in-depth case histories were obtained in order to rule out other possible complicating factors that might have contributed to a speech and language delay. The results of this study revealed essentially age-appropriate receptive language skills in this group of children. Expressive language and articulatory skills were significantly below chronological age level expectation, indicating the possible serious effects of chronic middle ear effusion on speech and language development.

Effect of middle-ear dysfunction and disease on hearing and language in high-risks infants.

The effect of middle-ear dysfunction and disease on hearing and language development at one year of age was evaluated for 143 high-risk infants. These infants were categorized as normal or abnormal based on otologic history, otoscopic examinations, and on tympanometric examinations. Language was significantly related to gestational age, being delayed by approximately the amount of prematurity. Language scores were therefore adjusted for gestational age. Speech-detection threshold was not related to gestational age, and was used as the measure of hearing. Hearing levels were negatively correlated with adjusted language quotients. Infants with abnormal otologic histories reported were not different from infants with normal histories in either hearing or language development. Infants with bilateral otoscopic abnormalities had significantly higher speech-detection thresholds, but did not differ in language development from those with bilaterally normal otoscopy. Infants who were abnormal bilaterally by tympanometric examination had significantly higher speech-detection thresholds as well as significantly delayed language development. A significant effect on both hearing and language was found among those infants bilaterally abnormal by tympanometry for whom evidence of middle-ear disease was not visualized by otoscopic examination. Implications of these findings are discussed.

Development and standardization of SCAN-A: test of auditory processing disorders in adolescents and adults.

This paper reports on the development and standardization of SCAN-A: Test of Auditory Processing Disorders in Adolescents and Adults. The standardization version of SCAN-A included six subtests; two filtered words (FW) subtests, two auditory figure-ground (AFG) subtests, a competing words (CW) subtest, and a competing sentences (CS) subtest. Studies included development of normative results on subjects at different ages, determination of subtests to retain in the final version, investigation of test-retest reliability, and a concurrent validity study comparing the results of SCAN-A to SCAN scores obtained on the same subjects. The final version of SCAN-A contains four subtests that take 20 minutes to administer. Raw scores can be converted to standard scores and percentile ranks. Cut-off scores are suggested for normal, questionable, and abnormal performance.

Development and standardization of SCAN-C Test for Auditory Processing Disorders in Children.

This paper reports on the development and standardization of SCAN-C: Test for Auditory Processing Disorders in Children-Revised. The revisions include new test instructions that have been reworded to make them easier for young children, aural stimuli presented on a compact disc, a revision of the Competing Words subtest, and the addition of a Competing Sentences subtest. Normative data on the new test were obtained on 650 children age 5 years, 0 months, to 11 years, 11 months. Analysis of new standardization data revealed systematic improvement in performance with increasing age. A new method of calculating the composite standard score gives equal weighting to each subtest of SCAN-C. Subtest test-retest reliability was substantially improved over the original SCAN, with SCAN-C correlations ranging from .65 to .82 for 5 to 7 year olds. Concurrent validity tests found that SCAN-C test results can be viewed with the same confidence as SCAN.

Central auditory processing in a patient with bilateral temporal lobe tumors: case report.

The purpose of this article is to report the audiologic and central auditory processing abilities of a 34-year-old male with a right temporal lobe tumor and a history of bilateral tumors of the temporal lobes. The patient was evaluated presurgical re-exploration and again at 2.5 months and 4 months postoperatively. Test results demonstrated little change in peripheral hearing abilities; however, marked fluctuations were recorded on several tests administered postoperatively. Overall, this patient demonstrated a wide range of performance on tests of central auditory function, notably scores that decreased postoperatively and returned to better than baseline on the SCAN-A and repeated abnormal scores on the Pitch Pattern Sequence Test and the Symbol Digit Modality Test. Auditory Fusion Test-Revised results were initially normal, were markedly abnormal immediately postoperative, and returned to normal during the second postoperative visit. Our purpose in conducting this case study was to demonstrate, with central auditory processing test findings as well as magnetic resonance images, functional disorders of communication in a pre- and postoperative patient with a temporal lobe tumor.

Effects of methylphenidate on the auditory processing abilities of children with attention deficit-hyperactivity disorder.

Stimulant medications are widely used as part of the treatment for children with attention deficit-hyperactivity disorder (ADHD). The current study investigated the effects of methylphenidate on auditory vigilance, auditory processing abilities, and receptive language abilities of children with ADHD. Twenty subjects (17 males and 3 females) ranged in age from 7 to 13 years. Each subject had been diagnosed as having ADHD and had been prescribed methylphenidate for the control of hyperactivity. The test battery included the Auditory Continuous Performance Test (ACPT), SCAN (a screening test for auditory processing disorders in children), and the Token Test for Children. Results indicated that there was significant improvement in the children's performance on all measures when on methylphenidate. Implications of these findings are discussed.

Validity of the Auditory Continuous Performance Test in differentiating central processing auditory disorders with and without ADHD.

The use of continuous performance tasks has been examined as a potential measure for clinical/laboratory identification of Attention-deficit/hyperactivity disorder. The present study compared the performance of 30 children, 26 boys and 4 girls ranging in age from 9-0 to 12-11, with central auditory processing disorders (CAPD) who did not meet criteria for coexisting ADHD with the performance of children with CAPD coexisting with ADHD (CAPD/ADHD) on the Auditory Continuous Performance Test (ACPT). In interpreting the results, the variability as well as the actual counts for correct responses and total errors were considered. Results indicated limited potential for the use of the ACPT in the differential diagnosis of ADHD. Implications of the results as well as considerations for future research are discussed.

An assessment technique for children with auditory-language processing problems.

The purpose of this study was to develop a new multilayer clinical assessment technique to evaluate auditory-language processing abilities in children. Following a 90-min in-service workshop on auditory-language processing problems, 46 nonhandicapped first-, second-, and third-grade students were referred by their classroom teachers for an evaluation of auditory-language processing abilities. Twelve "normally" achieving first-, second-, and third-grade students were randomly selected as controls. Standardized and nonstandardized measures included a pure tone and impedance test, selected subtests of the Clinical Evaluation of Language Functions (Linguistic Concepts, Relationships and Ambiguities, Oral Directions, Spoken Paragraphs, Word Associations, and Model Sentences), the Goldman-Fristoe-Woodcock (GFW) Memory for Sequence Test, Sound Mimicry Test, Sound-Symbol Association Test, and the GFW Test of Auditory Discrimination. Nonstandardized measures included an Observational Profile of Classroom Communication and an informal language sample. Results indicated 87% of 46 (n = 40) children were identified as having auditory-language processing problems. In-service training was an effective means to heighten teachers' awareness for referring subjects. Additionally, the Observational Profile of Classroom Communication was an effective procedure for teachers to systematically observe and document communication behaviors in the context of the classroom.

A comparison of the SSW and language test results.

The purpose of this paper is to determine the relationship between the SSW and a battery of auditory-language tests in a group of children suspected of auditory processing problems. Thirty-one children between the ages of 6.2 and 10.4 were referred by their classroom teachers. All children were administered a pure tone and an acoustic immittance battery, the SSW test, selected subtests of the Clinical Evaluation of Language Functions, the Goldman-Fristoe-Woodcock Auditory Skills Battery, an elicited language sample, and the Observational Profile of Classroom Communication. No significant correlations were found between the SSW right competing and left competing conditions and the auditory-language test battery. The findings suggest that these two test approaches measure different aspects of auditory processing abilities in children, and both are required to adequately describe auditory processing abilities at all levels.