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Biomedical subjects

S C Levine

Publications and source records attributed to S C Levine.

At least 37 records · Page 2Linked to original sources
PubMed1995

Calculation abilities in young children with different patterns of cognitive functioning.

This study examined the arithmetic calculation abilities of kindergarten and first-grade children with different patterns of cognitive functioning: children with low language but adequate spatial abilities (Low Language; n = 33, male = 42%); children with low spatial but adequate language abilities (Low Spatial; n = 21, male = 42%); children with general delays (Delayed; n = 21, male = 48%); and children with no language or spatial impairments (Nonimpaired; n = 33, male = 48%). Each child was given a series of addition and subtraction calculations presented as nonverbal problems, story problems, and number-fact problems. Story problems and number-fact problems require mastery of conventional verbal symbols, whereas nonverbal problems do not. The findings show that nonverbal, story, and number-fact problem formats are differentially sensitive to variation in cognitive ability. The Low Language group performed significantly worse than the Nonimpaired group on story problems but not on nonverbal problems or number-fact problems. The Delayed group performed significantly worse than the Nonimpaired group on nonverbal problems as well as on story problems but not on number-fact problems. The Low Spatial group did not differ significantly from the Nonimpaired group on any of the three problem types, although the overall performance of these children was weaker. When we adjusted for finger use on number-fact problems, the Nonimpaired group outperformed both the Low Language and the Delayed groups but not the Low Spatial group. Thus, the finding that the Low Language and Delayed groups perform as well as the Nonimpaired group on number-fact problems is attributable to their greater finger use.

Child↗
PubMed1994

A mental model for early arithmetic.

The authors examined young children's ability to solve nonverbal calculation problems in which they must determine how many items are in a hidden array after items have been added into or taken away from it. Earlier work showed that an ability to reliably solve such problems emerges earlier than verbal calculation ability but did not examine when it first appears. The authors propose that the ability to solve such problems involves domain-general symbolic processes similar to those involved in symbolic play and the use of physical models. Hence the ability to calculate should appear at about 2 years and should be related to overall level of intellectual competence. The authors show that the ability to reliably solve nonverbal calculation tasks emerges only after 2 years of age and that performance on nonverbal calculation problems is highly related to overall level of intellectual competence in children between 3 and 4 years of age.

Child Development↗
PubMed1994

Facial nerve stimulation produced by cochlear implants in patients with cochlear otosclerosis.

Thirty-eight adult cochlear implants have been performed at the University of Minnesota. Facial nerve stimulation by the implant in response to sound has been noted in four of these cases. Three of the four were patients whose sensorineural hearing loss was caused by cochlear otosclerosis. In each case it was possible to place the electrodes, however multiple leads had to be deprogrammed in order to avoid facial nerve stimulation. In each case characteristic radiographic findings of cochlear otosclerosis could be identified on preoperative temporal bone computed tomography scans. Although facial nerve stimulation has been described as a complication of cochlear implantation, it has not been reported to be associated with cochlear otosclerosis. Postoperative programming of the implant may be limited by facial nerve stimulation. In some cases these limits may reduce the efficacy of the device. This possibility should be taken into account during preoperative counseling of patients with cochlear otosclerosis considering cochlear implantation.

Aged↗
PubMed1993

Evaluation of patients with acoustic neuroma with dynamic posturography.

The purpose of the present work was to consider the use of posture tests in patients who had known acoustic tumors. The results suggest that it might be possible to determine whether the tumor is on the inferior or superior branch of the vestibular nerve. This would have clinical significance for planning a surgical approach to the tumor.

Aged↗
PubMed1993

Intracanalicular acoustic neuroma: early surgery for preservation of hearing.

Diagnosis of very small acoustic neuromas has become much more common since the advent of magnetic resonance imaging. Many of the patients so diagnosed have minimal unilateral hearing loss as their only symptom. Because limited information is available on the natural history and prognosis of these lesions, the choice of treatment is controversial. The authors review their recent experience with the surgical treatment of intracanalicular acoustic neuroma. The records of 14 consecutive patients with intracanalicular acoustic neuroma were reviewed with respect to type of presentation, pre- and postoperative facial and auditory nerve function, surgical approach, and complications. Detailed results for patients operated on to preserve hearing are presented. Presenting symptoms were nearly equally divided among diminished hearing, vertigo, and tinnitus. Eleven of the 14 patients had serviceable hearing preoperatively and nine (82%) remained in this condition postoperatively. Facial nerve function was unchanged by operation in 12 patients. Seven operations were performed through the middle fossa, five through the posterior fossa, and two by the translabyrinthine approach. The probability of preserving hearing during surgical excision of intracanalicular acoustic neuroma in patients with serviceable hearing exceeds 80%. Given the relative infrequency of serious complications and the likelihood of progressive hearing loss in the untreated patient, excision of such small tumors shortly after diagnosis may offer the best chance of long-term hearing preservation.

Adult↗
PubMed1993

Rehabilitation of the lower cranial nerves.

Brain stem lesions frequently cause dysfunction of the lower cranial nerves. Even with successful treatment, dysfunction may remain. Various methods for rehabilitating the patient with persistent lower cranial nerve dysfunction are presented.

Accessory Nerve↗
PubMed1993

Tympanic and transtympanic electrocochleography in acoustic neuroma and vestibular nerve section surgery.

Eighth nerve action potential (AP) amplitudes and latencies and cochlear microphonic (CM) amplitudes were compared using tympanic and transtympanic electrocochleography (ECOG) in two patient groups. Tympanic ECOG was performed with a wick electrode placed on the tympanic membrane (TM). Transtympanic ECOG was performed with a needle electrode placed on the promontory of the anesthetized patient. Eighteen subjects were tested by tympanic ECOG as part of a preoperative assessment for either acoustic neuroma removal or transection of the vestibular portion of the eighth cranial nerve. Surgery occurred within 1 week of the preoperative evaluation. Intraoperative auditory monitoring was performed using transtympanic ECOG. Baseline recordings were compared to the preoperative tympanic ECOG data. Stimuli were condensation and rarefaction clicks and tone bursts, presented by an insert earphone. As expected, the two methods resulted in essentially identical response latencies and large amplitude differences, although the response amplitudes were extremely variable. The AP amplitude and the CM amplitude did not increase by the same factor with the transtympanic (TT) electrode compared to the tympanic electrode. On comparison of preoperative and intraoperative response amplitudes with regard to stimulus polarity, tympanic electrocochleography appears to be a useful method of gathering preliminary information on the status of the patient's auditory system. In this study, tympanic ECOG was found to have some predictive value when trying to ascertain the best intraoperative monitoring situation.

Acoustic Stimulation↗
PubMed1992

Variations in characteristic perceptual asymmetry: modality specific and modality general components.

The current study investigates sources of between-subjects variation in asymmetry scores on visual half-field and dichotic listening tasks. For each of these presentation modalities, subjects were given multiple laterality tasks. Results indicate that about 50% of the between-subjects variations in asymmetry scores in each modality is attributable to individual differences in perceptual asymmetries that are not stimulus-specific, referred to as "characteristic perceptual asymmetries" in this paper. In addition, the question of whether individual differences in characteristic perceptual asymmetries are modality specific, modality general, or both was investigated by entering subjects' asymmetry scores from visual half-field and dichotic listening tasks into a principal component analysis. The results of this analysis indicate that there are both modality specific and modality general influences on subjects' characteristic perceptual asymmetries.

Adult↗
PubMed1992

Development of calculation abilities in young children.

This study investigates the development of skills for solving verbally and nonverbally presented calculation problems in children between 4 and 6 years of age. Identical addition and subtraction calculations were presented in three problem-type formats: nonverbal problems, story problems, and number-fact problems. The nonverbal problems involved presenting sets of physical referents that were then transformed either by adding or removing elements. The child saw the initial set and the number of elements that were added or removed, but not the final set. The task was to construct an array that contained the number of elements in the final set. The story problems and number-fact problems were presented orally, without props. Results indicate that children as young as 4 years of age have some success on the nonverbal problems, showing that they can transform sets by adding or subtracting elements. In contrast, children do not achieve comparable levels of success on the story problems or number-fact problems until 5 1/2 to 6 1/2 years of age. Moreover, throughout the age range tested, children performed better on nonverbal problems than on either story problems or number-fact problems. These results suggest that children's earliest ability to add and subtract is based on experiences combining and separating sets of objects in the world and that this ability precedes the development of conventional verbal methods of calculating.

Aptitude↗
PubMed1992

Effect of ear-canal air pressure on evoked otoacoustic emissions.

The effect of ear-canal air pressure on click-evoked otoacoustic emissions was measured for pressures ranging from 200 to -200 daPa and stimulus levels ranging from 60-90 dB PeSPL. Positive and negative ear-canal pressures (relative to ambient pressure) reduced the emission amplitude by 3-6 dB. A spectral analysis of the emissions revealed that the effect of ear-canal air pressure is that of a high-pass filter with a cutoff frequency of 2600 Hz and a slope of 4 dB/oct. The spectral changes are the expected effect of an increase in stiffness of the middle ear and were independent of pressure polarity and click level. Ear-canal air pressure substantially reduced the reproducibility of the emission waveform, in many cases rendering the emission indistinguishable from background noise. The implication of these findings for hearing screening applications is that a high false alarm rate may occur in normal-hearing patients with intratympanic air pressures that are significantly different from ambient pressure.

Adult↗
PubMed1992

Tympanic electrocochleography for evaluation of endolymphatic hydrops.

There has been increased interest in electrocochleography for the diagnosis and intraoperative monitoring of patients with endolymphatic hydrops. Attention has been focused on the determination of the summating potential:action potential (SP:AP) ratio from alternating polarity clicks. Review of this technique at the University of Minnesota led to a reevaluation of the usual interpretation of these recordings. Separate examination of the rarefaction and condensation click recordings provides insight into abnormal response patterns. Cases are presented to illustrate a variety of normal and abnormal patterns including abnormal differences in the latency of condensation and rarefaction-click-generated action potentials, increased summating potential, uncanceled cochlear microphonic, and reduced action potential and summating potential amplitudes. These response categories may be useful in understanding the pathophysiology of Meniere's disease.

Acoustic Stimulation↗
PubMed1992

Tympanic electrocochleography: normal and abnormal patterns of response.

Electrocochleography has been widely used in human and animal studies of endolymphatic hydrops. A variety of response patterns have been reported in normal and hydropic ears. Recent clinical studies have focused almost exclusively on the amplitude ratio of the summating potential (SP) and action potential (AP) derived from alternating polarity click responses. In this report normal response patterns are described with a tympanic membrane electrode employing condensation, rarefaction and alternating polarity clicks and tone burst stimulation. A variety of response abnormalities are described in patients with suspected endolymphatic hydrops. The exclusive use of alternating polarity clicks is not adequate to reveal the nature of these abnormalities.

Acoustic Stimulation↗
PubMed1991

Sources of between-subjects variability in perceptual asymmetries: a meta-analytic review.

A number of studies have reported correlations between subjects' asymmetry scores on left and right hemisphere specialized tasks. In this paper we report the results of meta-analyses performed on these correlations. Results showed positive correlations between subjects' asymmetry scores on left and right hemisphere specialized tasks in both modalities (asymmetry scores were computed as R-L for both left and right hemisphere specialized tasks). Thus, in both modalities, some of the between-subjects variability in asymmetry scores appears to reflect non-stimulus specific individual differences in perceptual asymmetry. For the visual asymmetry tasks, results also showed that the subjects' asymmetry scores on left and right hemisphere specialized tasks were more highly correlated under conditions of bilateral than unilateral input. This finding suggests that bilateral tasks may be more sensitive to "characteristic perceptual asymmetry" than unilateral tasks.

Dichotic Listening Tests↗
PubMed1991

Inferring patterns of hemispheric specialization for individual subjects from laterality data: a two-task criterion.

Sixty-three subjects (31 dextrals and 32 sinistrals) were given two visual half-field laterality tasks (recognition of words and faces). Subjects were classified as having typical or atypical hemispheric specialization on the basis of the relative magnitude of their asymmetry scores on the two laterality tasks. Those subjects whose word asymmetry scores were larger than their face asymmetry scores (asymmetry scores computed as RVF-LVF for both tasks) were classified into Group Typical and those subjects whose word asymmetry scores were smaller than their face asymmetry scores were classified into Group Atypical. For both dextrals and sinistrals, the proportion of subjects classified into Groups Typical and Atypical was consistent with estimates of the incidence of typical and atypical hemispheric asymmetry patterns based on sodium amytal testing. These results support the hypothesis that the relative magnitude of asymmetry scores on left and right hemisphere specialized tasks index individual differences in patterns of hemispheric specialization.

Adolescent↗
PubMed1991

Relative value of diagnostic tests for small acoustic neuromas.

Auditory brainstem response is now widely employed as a screening test for acoustic neuromas because it is equally sensitive when standardized against computed tomography. We have detected eight small (less than 10 mm) acoustic neuromas using gadolinium enhanced magnetic resonance imaging. In three of these cases, the auditory brainstem response was falsely negative. In contrast, 19 patients with larger tumors (greater than or equal to 10 mm) were found to have no false negative auditory brainstem responses. Auditory brainstem response appears to be less sensitive for detecting small, symptomatic acoustic neuromas.

Adult↗