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.

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.

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.

Central auditory evaluation of patients with spasmodic dysphonia.

Spasmodic dysphonia is a focal laryngeal dystonia characterized by inappropriate contractions of the intrinsic laryngeal musculature. The prevalence of associated neurological findings has led to detailed investigation of the central nervous system. Previous research revealed latency abnormalities in patients' auditory brainstem responses. The present study further investigated central auditory findings in patients with spasmodic dysphonia, including brainstem and cortical function. Fourteen normal-hearing patients with spasmodic dysphonia were tested using the auditory brainstem response (ABR) and SCAN-A test of central auditory processing. The ABR estimated brainstem transmission time and evaluated auditory pathway integrity at a high stimulus rate. SCAN-A assessed the auditory cerebral cortex. Implications of these findings are discussed. We found no ABR abnormalities in subjects with spasmodic dysphonia. Positive SCAN-A findings were negligible. The ABR findings contradict previous reports.

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.

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.

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.

Predictability of recovery from Bell's palsy using evoked electromyography.

The role of surgery in the treatment of idiopathic facial paralysis (Bell's Palsy) has been the subject of much controversy. Some have advocated aggressive surgical therapy to prevent nerve injury based on evoked electromyography (EEMG) results. The present study analyzes the outcome of 23 patients who presented with Bell's palsy and were evaluated with EEMG. Of the 15 patients who showed greater than 90 percent compound action potential reduction in the affected side, a widely used criterion for surgical decompression of the facial nerve, almost half (47%) had normal to near-normal recovery, and only three (20%) had residual severe dysfunction. Results infer that patients who meet surgical criteria based on EEMG results but who do not undergo surgery do not show a greater morbidity. The authors conclude that conservative criteria should be used when recommending facial nerve decompression.

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.

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.

Intraoperative facial nerve monitoring in chronic ear surgery: a resident training experience.

Intraoperative facial nerve monitoring has been accepted as a valuable adjunctive modality to be employed in a variety of neurotologic and skull base surgical procedures. However, the role that electrical or mechanical stimulation assessment plays in chronic ear surgery is less well defined, especially in a residency training program. In this study, 250 consecutive operative cases of chronic otitis media, with and without cholesteatoma were monitored with the Xomed-Treace Nerve Integrity Monitor, NIM-2 system. Data regarding electrophysiologic monitoring parameters; electromechanical artifact, including system failure; and surgical outcome were analyzed. Although not a substitute for anatomic identification of the facial nerve, intraoperative monitoring provides an additional technique to optimize resident surgical education.

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.

Evaluation of cochlear function in a patient with "far-advanced" otosclerosis.

A patient with "far-advanced" otosclerosis with a profound bilateral hearing loss was evaluated for cochlear reserve using transtympanic electrocochleography (ECoG) and promontory stimulation. Results indicated that both ECoG and promontory responses were present, indicating that cochlear function was present bilaterally. A stapedectomy resulted in closure of the air-bone gap. Postoperative hearing yielded excellent aided responses compared to no measurable preoperative hearing aid benefit. This case serves to demonstrate the value of evaluating cochlear function using these electrophysiologic techniques.

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.

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.

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.

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.

Management of the acoustic neuroma in an only hearing ear.

Heightened physician awareness of the sociologic and psychologic trauma related to deafness coupled with an increased emphasis on early diagnosis has prompted the employment of sophisticated diagnostic studies in an attempt at identification of an acoustic neuroma as a cause of hearing loss. Because profound bilateral hearing impairment is a catastrophic event, the management and care of an individual with an eighth nerve lesion in an only hearing ear remains a significant challenge for both patient and physician. In this article we will summarize our experience with this unique patient population through case presentations that will include diagnostic testing and intraoperative and perioperative findings. The literature regarding diagnosis and management will be reviewed. Recommendations for options available in the care of these patients will be discussed.