Four Dichotic Speech Tests Before and After Temporal Lobectomy

Abstract

Thirty patients were tested with four dichotic speech tests before and after temporal lobectomy for control of intractable seizures. Ipsilateral ear scores improved on all tests postoperatively; these improved scores reached statistical significance for the Staggered Spondaic Word Test and for consonant-vowel syllables. This result, combined with a nonsignificant decrease for contralateral ear scores, produced postoperative increase in the ipsilateral minus contralateral ear difference scores, similar to previous literature. Preoperative tests for a larger group of patients showed significantly poorer performance than for normal subjects, for all four tests. Total correct scores, used as a measure of overall auditory processing capacity, were impaired for these patients, but unchanged or slightly improved after surgery.Since the earliest report ( 1) which documented that temporal lobe lesions altered the perception of distorted speech presented to the ear contralateral to the lesion, many investigations have shown subtle auditory effects of central nervous system lesions (2-14). Similar discriminatory effects have been shown experimentally in animals (15, 16).Dichotic auditory tasks involve the presentation of different speech or tonal signals to the two ears simultaneously, and this technique has been useful in studying auditory effects of central nervous system (CNS) lesions. These have usually shown contralateral ear deficits for temporal lobe lesions (4, 6, 7) or bilateral deficits for left temporal lobe lesions (4, 8). A larger contralateral ear deficit has been reported for total hemispherectomy ( 17), and a left ear deficit for patients who have had corpus callosum section (18, 19).A similar kind of altered perception of the contralateral ear signal has been suggested on dichotic tonal or melodic tasks. For example, after temporal lobectomy, Shankweiler (20) reported decreased ability in dichotic melody recognition for the contralateral ear; and Efron and Crandall(2 1) reported a decreased salience for the contribution from the contralateral ear tone to dichotic chord perception.Patients who have had temporal lobectomy for control of seizures have been reported to show a contralateral ear deficit using a dichotic digits task (4, 22) and also using dichotic consonant-vowel (CV) syllables (7). Oxbury and Oxbury (22), using digits, found a significant contralateral ear deficit only if Heschl's gyrus was affected by the lobectomy. Olsen (23) found that, both before and after temporal lobectomy, 40% of patients evaluated for intractable seizures had normal dichotic CV test results for both ears.These previous reports provide information for a limited number of patients with temporal lobectomy, and only the latter study compared preoperative scores to a normal control population. It seemed important to us to extend the available data for these patients, as well as to study several different tests for the same patients. Our purpose is to monitor auditory performance before and after surgery, using readily obtaine...

Altered neural synchronization to pure tone stimulation in patients with mesial temporal lobe epilepsy: An MEG study

“…Hippocampal sclerosis may influence organized processing of bilateral ACs, in accord with recent conceptualizations of epilepsy as a network disease [54]. To date, various cognitive and psychiatric impairments [55] and CAP impairments have been found in patients with mTLE [2,5,6,[8][9][10][11][12][13]. Auditory dysfunction may be caused by impaired connectivity resulting from seizure propagation between the hemispheres.…”

“…In this context, altered CAP refers to changes in the perceptual processing of auditory information in the central nervous system despite normal hearing sensitivity, exhibited as poor auditory discrimination performance, auditory pattern recognition and temporal differentiation [2][3][4]. For example, patients with mTLE show decreased performance in dichotic listening [5][6][7] to both verbal and nonverbal sounds [8], poor performance in anisochrony or irregularity discrimination of rapid auditory sequences [9], and decreased temporal processing in the Gaps-In-Noise test [10] and the duration pattern sequence test [11]. Intractable patients with right mTLE are at risk of speech recognition impairment in real-world listening environments compared with extratemporal lobe epilepsy [12].…”

Effect of lateralized epileptic discharges on the thought flow

“…Collard et al 32 , using verbal dichotic tests in epileptic patients, observed after temporal lobectomy an improvement of the responses in the ipsilateral ear and suggest that paroxysmal activity produces an inhibitory influence in contralateral cortex function.…”

The role of the temporal pole in auditory processing

“…Working in animals, Masterton (2) conclusively demonstrated that the temporal pole and the amygdala are involved in auditory processing, and it is also known that the geniculoamygdaloid pathway plays an importantfunctional role in hearing [1][2][3]. Beginning in 1961, Kimura (4) showed that anterior temporal lobectomy in humans resulted in partial or total abolition of dichotic listening test scores for sounds or messages delivered to the ear contralateral to the operated temporal lobe [4][5][6]. In 1972, Berlin (7) detected subjective auditory deficits following anterior temporal lobectomy [7][8][9] bat only the investigation of Jacobson (10) included objective electrophysiological data.…”