Journal of Clinical and Experimental Neuropsychology
ISSN: 0168-8634 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/ncen19
Dichotic listening and complex partial seizures Richard J. Roberts , Nils R. Varney , Jane S. Paulsen & Emily D. Richardson To cite this article: Richard J. Roberts , Nils R. Varney , Jane S. Paulsen & Emily D. Richardson (1990) Dichotic listening and complex partial seizures, Journal of Clinical and Experimental Neuropsychology, 12:4, 448-458, DOI: 10.1080/01688639008400992 To link to this article: http://dx.doi.org/10.1080/01688639008400992
Published online: 04 Jan 2008.
Submit your article to this journal
Article views: 7
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Citing articles: 25 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ncen20 Download by: [Central Michigan University]
Date: 10 October 2015, At: 06:57
Journal of Clinical and Experimental Neuropsychology 1990, Vol. 12, No. 4, pp. 448458
0168-8634/90/12W0448$3.00 Q Swets & Zeitlinger
Dichotic Listening and Complex Partial Seizures"
Downloaded by [Central Michigan University] at 06:57 10 October 2015
Richard J. Roberts, Nils R. Varney, Jane S. Paulsen, and Emily D. Richardson Iowa City VA Medical Center and University of Iowa
ABSTRACT This study reports on 24 patients with multiple symptoms of untreated complex partial seizures (CPSz) who performed poorly at baseline assessment on a brief dichotic word listening task and subsequently improved following successful anticonvulsant therapy directed at treating seizure symptoms. These preliminary findings suggest that, in the absence of rnacroscopic structural lesions, dynamic electrophysiological dysfunction may interfere with the processing and transmission of simultaneously presented auditory information.
Although it is well established that impaired dichotic listening performance may result from many types of structural lesions (Springer, 1986) there have been few studies of dichotic listening performance in patients with electrophysiological dysfunction or paroxysmal disorders (Fincham, Yamada, Schottelius, Hayreh, & Damasio, 1979; Mazzucchi & Parma, 1978; Mazzucchi, Visintini, Magnani, Cattelani, & Parma, 1985; McIntyre, Pritchard, & Lombroso, 1976). Accordingly, the primary purpose of the present study is to describe the various patterns of abnormal dichotic listening performance which can be exhibited by patients with untreated symptoms of complex partial seizures (CPSz). The secondary purpose is to establish that some dichotic listening performance deficits in such seizure patients may be normalized or substantially ameliorated when their seizure symptoms are successfully treated with anticonvulsant medication.
* The authors are grateful to Marc E. Hines and two anonymous reviewers for their critical comments on an earlierdraft of this manuscript. The authors also wish to acknowledge the technical assistance of Lon Gorrnan, Jane Kraus, and Carla Blank in conducting the present research. This research was supported by funds from the Veterans Administration. This study is based in part on a paper presented at the 17th Annual Meeting of the International Neuropsychological Society at Vancouver, February 1989. Address reprint requests to: Richard J. Roberts, Ph.D., VA Medical Center (116B), Iowa City, IA 52246; U.S.A. Accepted for publication: May 15, 1989.
DICHOTIC LISTENING AND COMPLEX PARTIAL SEIZURES
449
Downloaded by [Central Michigan University] at 06:57 10 October 2015
METHOD Subjects Subjects were 24 patients who: (1) endorsed at least seven of 19 symptoms associated with CPSz on a structured interview during initial clinical assessment; (2) were subsequently regarded as having been successfully treated for their seizure symptoms by their attending physicians; and (3) manifested impaired dichotic word-listening performance at baseline (i.e., at least one dichotic listening index below the fifth centile of the control distribution) or borderline performance (i.e., at least one index below the tenth centile of controls) which subsequently improved after successful treatment of target symptoms with anticonvulsant medications. This series of cases consisted of 22 males and 2 females, with ages varying from 19 to 68 years ( M = 42.0, SD = 1 1.6) and educational level ranging from 8 to 16 years ( M = 13.3, SD = 1.9). All but two patients (patients 10 and 13) were right-handed. Additional demographic and neurodiagnostic data are presented in Table 1 . As can be seen from the table, all patients reported a history of some type of CNS insult capable of producing cerebral dysfunction, most frequently single or multiple episodes of mild-to-moderate closed cranial trauma (CCT) or extremely high fevers (2 104' F, 40OC) in adulthood. Of the 23 patients who received either standard, sleep-deprived, or 24-hour ambulatory EEG evaluations prior to treatment, 65% (15/23) manifested electrophysiologic abnormalities. Of the 15 patients with abnormal EEG findings, eight patients were regarded as manifesting epileptiform activity by the consulting electroencephalographer, (patients 5, 6, 7, 11, 15, 20, 23, 24 in Table l ) , and the remaining seven patients exhibited brain wave activity which was regarded as abnormal, but not necessarily diagnostic of epilepsy (patients 2, 12, 13, 17, 18, 19, 22). Of the 11 patients who received CT scans, only three had abnormal scans, two patients with small lesions in the frontal lobes and one with a tiny lacunar infarct in the postero-inferior aspect of the left putamen. Control subjects were 2 4 hospital employee volunteers (1 8 males, 6 females) with a negative history for CCT and other types of CNS disease. All but three controls were strongly right-handed. Ages of controls ranged from 19 to 66 years (M= 39.2, SD = 1.8). Although the mean ages of the two samples were not significantly different, t (46) = -.90, ns, there was a significant difference in mean years of formal education between patients and controls, t (46) = 2.01, P < .05; however, within the control sample, years of education was not significantly correlated with dichotic listening performance on the #Both index (described below as the best measure of overall efficiency of task performance). Procedure Seizure Symptom Interview. As part of a larger investigation of the phenomenology of seizure symptoms, patients referred for neuropsychological evaluation were routinely administered a structured interview to determine the presence and frequency of common symptoms of CPSz (Neppe, 1981,1983; Roberts, Paulsen, & Varney, 1988). In almost all cases, a family member or reliable informant was also interviewed, and, when the ancillary informant confirmed the presence of a symptom initially denied by the patient (e.g., staring spells), the symptom was regarded as present. The 19 symptoms comprising the interview are presented in Table 2, with symptoms grouped according to whether they are predominantly within the sensory, cognitive/motoric, or affective domains. The mean number of CPSz-like symptoms endorsed by the patient sample was 13.4 (SD = 3.5). D i c b t i c Word Listening Task. A modified version of the dichotic listening task developed by Damasio and Damasio (1979) was administered to all subjects. Stimuli were common English words varying from one to three syllables in length. The first 10 stimuli, which were practice items, involved presentation of a single word to either the right or left ear. On the succeeding 50 test trials, word pairs were presented simultaneously, one word
450
RICHARD J. ROBERTS ET AL.
Table 1: Demographic and Neurodiagnostic Characteristics of Seizure Patients Patient#
Year of Education
Sex
Presumed Etiology'
40
10 14
M M
CCT CCT
18 13
13 12 12
M
5
36 47 19
F
CCT, fever CCT CCT
14 12 9
6
40
12
M
CCT (x2)
18
7
37
13
M
CCT (x2)
10
8 9 10 11
41 42 36 59
15 16 16
M M M M
CCT CCT (x3) CCT, fever CCT
10 12 18 9
12
39
13
M
14
13
57
13
M
CCT (x6), fever CCT
14
43
12
M
11
15
63
14
M
16
27
12
M
17
68
8
M
18
37
16
M
CCT, fever hypoxia CCT, fever Birth hypoxia, fever CVA, hypoxia fever
19
53
12
M
20
50
12
M
21 22
34 37
14 14
M M
23
31
15
M
24
28
13
F
1 2 3
Downloaded by [Central Michigan University] at 06:57 10 October 2015
4
a
Age 44
15
M
#CPSz Symptomsb
18
14 12 7 13
CCT, electrocution CCT
10
CCT Toxic coma CCT
15 18
CCT, fever
17
Closed cranial trauma is abbreviated CCT. Maximum score = 19.
18
11
EEG Findings Normal (x3) Diffuse theta, R. hemisphere spiking Normal Normal Bi-fronto temporal spiking Bi-front0 temporal spiking R.frontal spikeand-wave paroxysmal theta Not Available Normal (x2) Normal Bi-frontal sharp waves Intermittent temporal slowing Continuous bi-frontal slowing Normal Right temporal spiking Normal
L. temporal delta slow waves R.frontal spikes and sharp waves Diffuse delta slow waves L > R temporal theta transients Normal Diffuse theta bursts Bi-temporal spike-and-wave R. frontotemporal spike-and-wave
DICHOTIC LISTENING AND COMPLEX PARTIAL SEIZURES
45 1
Downloaded by [Central Michigan University] at 06:57 10 October 2015
Table 2: Complaints Comprising the Seizure Symptom Interview Sensory Olfactory Illusions Gustatory Illusions Visual Illusions Haptic Illusions Episodic Anesthesias Auditory Illusions Sick Headaches Cognitive/Motoric Episodic Speech Problems Confusional Spells Jamais Vu Deja Vu Memory Gaps Automatic/Unrecalled Behaviors Staring Spells Subjective Mental Decline Unexplained Loss of Consciousness Affective Dysphoria: Chronic Depression, Square-Wave Mood Swings Unexplained Panic, Abrupt Anxiety Rage Attacks/Episodic Dyscontrol
to the right ear and the other to the left. In each stimulus pair, words were of identical duration and contained the same number of syllables. Although the Damasios’ original task consisted of 110 such trials, pilot work in our laboratory indicated that 50 trials were sufficient to establish reliable performance levels. Stimuli were presented over Koss K-20 stereo earphones via an Aiwa model S-WZ00 stereo cassette player at roughly 75 dB peak equivalent sound pressure level (SPL). Prior to performing the dichotic task, all patients and controls were tested for pure tone audiometry thresholds using an Eckstein model 60 audiometer set at 1000,2000, and 4000 Hz. Only subjects whose hearing was intact or who manifested mild (i.e., no more than 25 dB deficit at any one frequency tested) but bilaterally symmetric hearing loss (i.e., both ears within 10 dB of one another) were included. Subjects were required to repeat the words heard in each ear immediately after they were presented, and correct responses were recorded separately for the left (#Left) and right (#Right) channels. The number of trials on which both stimuli were correctly reported (#Both) was computed at the end of the procedure. The Laterality Index (LI). (#R - #L/#R + #L) X 100, used by Damasio and Damasio (1979) to determine if an individual subject manifested a significant relative unilateral extinction, was also calculated. This index, which is essentially a difference score between right and left channels corrected for overall level of performance, is free to vary between +lo0 (complete left-ear suppression) and -100 (complete right-ear suppression), with a score of 0 indicating equal efficiency in reporting from both channels. Because extreme positive and negative scores are both indicative of impaired performance, the absolute value of the Laterality Index, ILII, was employed for all statistical analyses.
Downloaded by [Central Michigan University] at 06:57 10 October 2015
452
RICHARD J. ROBERTS ET AL.
Baseline Testing and Posttreatment Follow-up. Prior to the seizure symptom interview, the dichotic listening task was administered to patients, typically as part of a 90-min neuropsychological exam. Baseline testing was accomplished prior to anticonvulsant treatment. For reasons unrelated to the present study, patients 11 and 14 were initially tested on carbamazepine, subsequently tested after having been withdrawn from the drug, for at least 3 months, and then restarted on carbamazepine. For clarity of data presentation, the initial dichotic listening scores for these two patients will subsequently be treated as “follow-up” testing (i.e., rather than a true “AB” design, those two patients underwent a “BAB” design). Follow-up testing occurred no sooner than 30 days after a patient was judged by the treating physician to have achieved therapeutic blood levels on anticonvulsant medication. At follow-up, all but four patients had stable serum carbamazepine (Tegretol) levels between 6.0 and 12.0 pg/ml. Of the remaining four patients, one (patient 15) was regarded as improved but incompletely treated with a serum carbamazepine level of 4.0. and three others (patients 1, 3, and 4) were treated with phenytoin (Dilantin). In order to substantiate the favorable opinions of the treating physicians with regard to clinical response to medication, patients were re-interviewed whenever possible at follow-up with regard to the presence and frequency of residual symptoms of CPSz. In order to compensate for the nonblind nature of the follow-up interview, a fairly conservative criterion was adopted for deciding whether a given seizure symptom was still present: if a previously endorsed symptom was reported to have occurred at least once in the month following maximal therapeutic benefit, it was regarded as still present. In all, 18 of 24 patients were re-interviewed within 1 week of posttesting on the dichotic listening task. In addition, because recent observations suggest that the MMPI (Hathaway & McKinley, 1951) can be surprisingly sensitive index of improved behavioral functioning when patients with multiple CPSz-like symptoms are successfully treated with anticonvulsants (Hermann & Melyn, 1984; Roberts et al., 1988), the pre- and posttreatment MMPI profiles of the 12 patients who completed the test at baseline and follow-up were also examined.
RESULTS
Control Performance Descriptive statistics for control performance on the dichotic listening task are presented in Table 3. As can be seen from the table, the task proved quite easy for controls, with n o control obtaining a score of fewer than 35 words correctly reported from a given ear. Control subjects failed to manifest the customary modest right-ear advantage for verbal stimuli, t (23) = -1.52, ns, presumably because the task was so easy. Fifteen subjects performed better in the right ear, six performed better in the left ear, and three performed equally well in both channels. As commonly recommended (e.g., Benton, Hamsher, Varney, & Spreen, 1983; McKhann et al., 1984), the fifth centile of the control distribution was chosen as the cutoff for establishing defective performance on all dichotic listening indices (including the laterality index). Because 95% o f control subjects obtained scores greater than 36 words per ear when data from right and left channels were pooled, scores of 36 and below were regarded as defective #Left and #Right scores. For the #Both score, an index of overall task efficiency,
DICHOTIC LISTENING AND COMPLEX PARTIAL SEIZURES
453
Table 3: Descriptive Statistics for Control Dichotic Listening Performance Dichotic Listening Score
M
Downloaded by [Central Michigan University] at 06:57 10 October 2015
SD Range Cutoff for Defective Performance
#Left
#Right
#Both
LI
41.6 2.6 36-46
42.7 3.9 35-47
37.3 4.6 27-45
3.5' 2.6 -7.9-+9.5
36
36
29
I-8.0 2+10.0
Note: N = 24. Maximum score = 50 for #Left, #Right, and #Both scores. Laterality Index lLIl vanes between -100 and +loo. ' M for LI is based upon the absolute value, ILII.
values of 29 and below were regarded as defective. LI scores greater than +10 were regarded as indicating relative left-ear suppressions, whereas LI values below -8 were regarded as evidence of right-ear suppression.
Patients' Initial Status Individual dichotic listening data for each of the 24 patients prior to and following treatment is presented in Table 4. Fourteen patients (54%) manifested bilaterally impaired performance, 5 performed defectively only in the right channel, 2 performed defectively only in the left channel, and 3 patients (7 through 9) manifested borderline performance (i.e., below the tenth centile of the control distribution) in one ear with performance within normal limits (i.e., at or above the tenth centile for controls) in the other ear. Eighty three percent of the sample (20/24) fell in the defective range on the #Both score. Eleven patients (#lo through 20) manifested left-ear suppressions, and four (#21 through 24) were right-ear suppressors. Eight of the nine remaining patients (#1-5 and 7-9) had LI scores within the range of variability of the control group, indicating comparable levels of performance from both right and left channels. Patient 6 was so impaired at baseline that he produced no correct responses from either ear after 25 trials (despite correctly reporting all 10 monaurally presented practice items), and the task was discontinued for humanitarian reasons, with the patient being assigned scores of 0 for both ears. As expected, multiple Mann-Whitney U tests confirmed that patients performed at significantly lower levels on all four dichotic listening indices than did controls: #Left (p < .OOOl), #Right @ < .OOOl), ##Both(p < .OOOl), and LI (p
ISSN: 0168-8634 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/ncen19
Dichotic listening and complex partial seizures Richard J. Roberts , Nils R. Varney , Jane S. Paulsen & Emily D. Richardson To cite this article: Richard J. Roberts , Nils R. Varney , Jane S. Paulsen & Emily D. Richardson (1990) Dichotic listening and complex partial seizures, Journal of Clinical and Experimental Neuropsychology, 12:4, 448-458, DOI: 10.1080/01688639008400992 To link to this article: http://dx.doi.org/10.1080/01688639008400992
Published online: 04 Jan 2008.
Submit your article to this journal
Article views: 7
View related articles
Citing articles: 25 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ncen20 Download by: [Central Michigan University]
Date: 10 October 2015, At: 06:57
Journal of Clinical and Experimental Neuropsychology 1990, Vol. 12, No. 4, pp. 448458
0168-8634/90/12W0448$3.00 Q Swets & Zeitlinger
Dichotic Listening and Complex Partial Seizures"
Downloaded by [Central Michigan University] at 06:57 10 October 2015
Richard J. Roberts, Nils R. Varney, Jane S. Paulsen, and Emily D. Richardson Iowa City VA Medical Center and University of Iowa
ABSTRACT This study reports on 24 patients with multiple symptoms of untreated complex partial seizures (CPSz) who performed poorly at baseline assessment on a brief dichotic word listening task and subsequently improved following successful anticonvulsant therapy directed at treating seizure symptoms. These preliminary findings suggest that, in the absence of rnacroscopic structural lesions, dynamic electrophysiological dysfunction may interfere with the processing and transmission of simultaneously presented auditory information.
Although it is well established that impaired dichotic listening performance may result from many types of structural lesions (Springer, 1986) there have been few studies of dichotic listening performance in patients with electrophysiological dysfunction or paroxysmal disorders (Fincham, Yamada, Schottelius, Hayreh, & Damasio, 1979; Mazzucchi & Parma, 1978; Mazzucchi, Visintini, Magnani, Cattelani, & Parma, 1985; McIntyre, Pritchard, & Lombroso, 1976). Accordingly, the primary purpose of the present study is to describe the various patterns of abnormal dichotic listening performance which can be exhibited by patients with untreated symptoms of complex partial seizures (CPSz). The secondary purpose is to establish that some dichotic listening performance deficits in such seizure patients may be normalized or substantially ameliorated when their seizure symptoms are successfully treated with anticonvulsant medication.
* The authors are grateful to Marc E. Hines and two anonymous reviewers for their critical comments on an earlierdraft of this manuscript. The authors also wish to acknowledge the technical assistance of Lon Gorrnan, Jane Kraus, and Carla Blank in conducting the present research. This research was supported by funds from the Veterans Administration. This study is based in part on a paper presented at the 17th Annual Meeting of the International Neuropsychological Society at Vancouver, February 1989. Address reprint requests to: Richard J. Roberts, Ph.D., VA Medical Center (116B), Iowa City, IA 52246; U.S.A. Accepted for publication: May 15, 1989.
DICHOTIC LISTENING AND COMPLEX PARTIAL SEIZURES
449
Downloaded by [Central Michigan University] at 06:57 10 October 2015
METHOD Subjects Subjects were 24 patients who: (1) endorsed at least seven of 19 symptoms associated with CPSz on a structured interview during initial clinical assessment; (2) were subsequently regarded as having been successfully treated for their seizure symptoms by their attending physicians; and (3) manifested impaired dichotic word-listening performance at baseline (i.e., at least one dichotic listening index below the fifth centile of the control distribution) or borderline performance (i.e., at least one index below the tenth centile of controls) which subsequently improved after successful treatment of target symptoms with anticonvulsant medications. This series of cases consisted of 22 males and 2 females, with ages varying from 19 to 68 years ( M = 42.0, SD = 1 1.6) and educational level ranging from 8 to 16 years ( M = 13.3, SD = 1.9). All but two patients (patients 10 and 13) were right-handed. Additional demographic and neurodiagnostic data are presented in Table 1 . As can be seen from the table, all patients reported a history of some type of CNS insult capable of producing cerebral dysfunction, most frequently single or multiple episodes of mild-to-moderate closed cranial trauma (CCT) or extremely high fevers (2 104' F, 40OC) in adulthood. Of the 23 patients who received either standard, sleep-deprived, or 24-hour ambulatory EEG evaluations prior to treatment, 65% (15/23) manifested electrophysiologic abnormalities. Of the 15 patients with abnormal EEG findings, eight patients were regarded as manifesting epileptiform activity by the consulting electroencephalographer, (patients 5, 6, 7, 11, 15, 20, 23, 24 in Table l ) , and the remaining seven patients exhibited brain wave activity which was regarded as abnormal, but not necessarily diagnostic of epilepsy (patients 2, 12, 13, 17, 18, 19, 22). Of the 11 patients who received CT scans, only three had abnormal scans, two patients with small lesions in the frontal lobes and one with a tiny lacunar infarct in the postero-inferior aspect of the left putamen. Control subjects were 2 4 hospital employee volunteers (1 8 males, 6 females) with a negative history for CCT and other types of CNS disease. All but three controls were strongly right-handed. Ages of controls ranged from 19 to 66 years (M= 39.2, SD = 1.8). Although the mean ages of the two samples were not significantly different, t (46) = -.90, ns, there was a significant difference in mean years of formal education between patients and controls, t (46) = 2.01, P < .05; however, within the control sample, years of education was not significantly correlated with dichotic listening performance on the #Both index (described below as the best measure of overall efficiency of task performance). Procedure Seizure Symptom Interview. As part of a larger investigation of the phenomenology of seizure symptoms, patients referred for neuropsychological evaluation were routinely administered a structured interview to determine the presence and frequency of common symptoms of CPSz (Neppe, 1981,1983; Roberts, Paulsen, & Varney, 1988). In almost all cases, a family member or reliable informant was also interviewed, and, when the ancillary informant confirmed the presence of a symptom initially denied by the patient (e.g., staring spells), the symptom was regarded as present. The 19 symptoms comprising the interview are presented in Table 2, with symptoms grouped according to whether they are predominantly within the sensory, cognitive/motoric, or affective domains. The mean number of CPSz-like symptoms endorsed by the patient sample was 13.4 (SD = 3.5). D i c b t i c Word Listening Task. A modified version of the dichotic listening task developed by Damasio and Damasio (1979) was administered to all subjects. Stimuli were common English words varying from one to three syllables in length. The first 10 stimuli, which were practice items, involved presentation of a single word to either the right or left ear. On the succeeding 50 test trials, word pairs were presented simultaneously, one word
450
RICHARD J. ROBERTS ET AL.
Table 1: Demographic and Neurodiagnostic Characteristics of Seizure Patients Patient#
Year of Education
Sex
Presumed Etiology'
40
10 14
M M
CCT CCT
18 13
13 12 12
M
5
36 47 19
F
CCT, fever CCT CCT
14 12 9
6
40
12
M
CCT (x2)
18
7
37
13
M
CCT (x2)
10
8 9 10 11
41 42 36 59
15 16 16
M M M M
CCT CCT (x3) CCT, fever CCT
10 12 18 9
12
39
13
M
14
13
57
13
M
CCT (x6), fever CCT
14
43
12
M
11
15
63
14
M
16
27
12
M
17
68
8
M
18
37
16
M
CCT, fever hypoxia CCT, fever Birth hypoxia, fever CVA, hypoxia fever
19
53
12
M
20
50
12
M
21 22
34 37
14 14
M M
23
31
15
M
24
28
13
F
1 2 3
Downloaded by [Central Michigan University] at 06:57 10 October 2015
4
a
Age 44
15
M
#CPSz Symptomsb
18
14 12 7 13
CCT, electrocution CCT
10
CCT Toxic coma CCT
15 18
CCT, fever
17
Closed cranial trauma is abbreviated CCT. Maximum score = 19.
18
11
EEG Findings Normal (x3) Diffuse theta, R. hemisphere spiking Normal Normal Bi-fronto temporal spiking Bi-front0 temporal spiking R.frontal spikeand-wave paroxysmal theta Not Available Normal (x2) Normal Bi-frontal sharp waves Intermittent temporal slowing Continuous bi-frontal slowing Normal Right temporal spiking Normal
L. temporal delta slow waves R.frontal spikes and sharp waves Diffuse delta slow waves L > R temporal theta transients Normal Diffuse theta bursts Bi-temporal spike-and-wave R. frontotemporal spike-and-wave
DICHOTIC LISTENING AND COMPLEX PARTIAL SEIZURES
45 1
Downloaded by [Central Michigan University] at 06:57 10 October 2015
Table 2: Complaints Comprising the Seizure Symptom Interview Sensory Olfactory Illusions Gustatory Illusions Visual Illusions Haptic Illusions Episodic Anesthesias Auditory Illusions Sick Headaches Cognitive/Motoric Episodic Speech Problems Confusional Spells Jamais Vu Deja Vu Memory Gaps Automatic/Unrecalled Behaviors Staring Spells Subjective Mental Decline Unexplained Loss of Consciousness Affective Dysphoria: Chronic Depression, Square-Wave Mood Swings Unexplained Panic, Abrupt Anxiety Rage Attacks/Episodic Dyscontrol
to the right ear and the other to the left. In each stimulus pair, words were of identical duration and contained the same number of syllables. Although the Damasios’ original task consisted of 110 such trials, pilot work in our laboratory indicated that 50 trials were sufficient to establish reliable performance levels. Stimuli were presented over Koss K-20 stereo earphones via an Aiwa model S-WZ00 stereo cassette player at roughly 75 dB peak equivalent sound pressure level (SPL). Prior to performing the dichotic task, all patients and controls were tested for pure tone audiometry thresholds using an Eckstein model 60 audiometer set at 1000,2000, and 4000 Hz. Only subjects whose hearing was intact or who manifested mild (i.e., no more than 25 dB deficit at any one frequency tested) but bilaterally symmetric hearing loss (i.e., both ears within 10 dB of one another) were included. Subjects were required to repeat the words heard in each ear immediately after they were presented, and correct responses were recorded separately for the left (#Left) and right (#Right) channels. The number of trials on which both stimuli were correctly reported (#Both) was computed at the end of the procedure. The Laterality Index (LI). (#R - #L/#R + #L) X 100, used by Damasio and Damasio (1979) to determine if an individual subject manifested a significant relative unilateral extinction, was also calculated. This index, which is essentially a difference score between right and left channels corrected for overall level of performance, is free to vary between +lo0 (complete left-ear suppression) and -100 (complete right-ear suppression), with a score of 0 indicating equal efficiency in reporting from both channels. Because extreme positive and negative scores are both indicative of impaired performance, the absolute value of the Laterality Index, ILII, was employed for all statistical analyses.
Downloaded by [Central Michigan University] at 06:57 10 October 2015
452
RICHARD J. ROBERTS ET AL.
Baseline Testing and Posttreatment Follow-up. Prior to the seizure symptom interview, the dichotic listening task was administered to patients, typically as part of a 90-min neuropsychological exam. Baseline testing was accomplished prior to anticonvulsant treatment. For reasons unrelated to the present study, patients 11 and 14 were initially tested on carbamazepine, subsequently tested after having been withdrawn from the drug, for at least 3 months, and then restarted on carbamazepine. For clarity of data presentation, the initial dichotic listening scores for these two patients will subsequently be treated as “follow-up” testing (i.e., rather than a true “AB” design, those two patients underwent a “BAB” design). Follow-up testing occurred no sooner than 30 days after a patient was judged by the treating physician to have achieved therapeutic blood levels on anticonvulsant medication. At follow-up, all but four patients had stable serum carbamazepine (Tegretol) levels between 6.0 and 12.0 pg/ml. Of the remaining four patients, one (patient 15) was regarded as improved but incompletely treated with a serum carbamazepine level of 4.0. and three others (patients 1, 3, and 4) were treated with phenytoin (Dilantin). In order to substantiate the favorable opinions of the treating physicians with regard to clinical response to medication, patients were re-interviewed whenever possible at follow-up with regard to the presence and frequency of residual symptoms of CPSz. In order to compensate for the nonblind nature of the follow-up interview, a fairly conservative criterion was adopted for deciding whether a given seizure symptom was still present: if a previously endorsed symptom was reported to have occurred at least once in the month following maximal therapeutic benefit, it was regarded as still present. In all, 18 of 24 patients were re-interviewed within 1 week of posttesting on the dichotic listening task. In addition, because recent observations suggest that the MMPI (Hathaway & McKinley, 1951) can be surprisingly sensitive index of improved behavioral functioning when patients with multiple CPSz-like symptoms are successfully treated with anticonvulsants (Hermann & Melyn, 1984; Roberts et al., 1988), the pre- and posttreatment MMPI profiles of the 12 patients who completed the test at baseline and follow-up were also examined.
RESULTS
Control Performance Descriptive statistics for control performance on the dichotic listening task are presented in Table 3. As can be seen from the table, the task proved quite easy for controls, with n o control obtaining a score of fewer than 35 words correctly reported from a given ear. Control subjects failed to manifest the customary modest right-ear advantage for verbal stimuli, t (23) = -1.52, ns, presumably because the task was so easy. Fifteen subjects performed better in the right ear, six performed better in the left ear, and three performed equally well in both channels. As commonly recommended (e.g., Benton, Hamsher, Varney, & Spreen, 1983; McKhann et al., 1984), the fifth centile of the control distribution was chosen as the cutoff for establishing defective performance on all dichotic listening indices (including the laterality index). Because 95% o f control subjects obtained scores greater than 36 words per ear when data from right and left channels were pooled, scores of 36 and below were regarded as defective #Left and #Right scores. For the #Both score, an index of overall task efficiency,
DICHOTIC LISTENING AND COMPLEX PARTIAL SEIZURES
453
Table 3: Descriptive Statistics for Control Dichotic Listening Performance Dichotic Listening Score
M
Downloaded by [Central Michigan University] at 06:57 10 October 2015
SD Range Cutoff for Defective Performance
#Left
#Right
#Both
LI
41.6 2.6 36-46
42.7 3.9 35-47
37.3 4.6 27-45
3.5' 2.6 -7.9-+9.5
36
36
29
I-8.0 2+10.0
Note: N = 24. Maximum score = 50 for #Left, #Right, and #Both scores. Laterality Index lLIl vanes between -100 and +loo. ' M for LI is based upon the absolute value, ILII.
values of 29 and below were regarded as defective. LI scores greater than +10 were regarded as indicating relative left-ear suppressions, whereas LI values below -8 were regarded as evidence of right-ear suppression.
Patients' Initial Status Individual dichotic listening data for each of the 24 patients prior to and following treatment is presented in Table 4. Fourteen patients (54%) manifested bilaterally impaired performance, 5 performed defectively only in the right channel, 2 performed defectively only in the left channel, and 3 patients (7 through 9) manifested borderline performance (i.e., below the tenth centile of the control distribution) in one ear with performance within normal limits (i.e., at or above the tenth centile for controls) in the other ear. Eighty three percent of the sample (20/24) fell in the defective range on the #Both score. Eleven patients (#lo through 20) manifested left-ear suppressions, and four (#21 through 24) were right-ear suppressors. Eight of the nine remaining patients (#1-5 and 7-9) had LI scores within the range of variability of the control group, indicating comparable levels of performance from both right and left channels. Patient 6 was so impaired at baseline that he produced no correct responses from either ear after 25 trials (despite correctly reporting all 10 monaurally presented practice items), and the task was discontinued for humanitarian reasons, with the patient being assigned scores of 0 for both ears. As expected, multiple Mann-Whitney U tests confirmed that patients performed at significantly lower levels on all four dichotic listening indices than did controls: #Left (p < .OOOl), #Right @ < .OOOl), ##Both(p < .OOOl), and LI (p
