Alcohol, Vol. 7, pp. 311-313. ©Pergamon Press plc, 1990. Printed in the U.S.A.
0741-8329/90 $3.00 + .00
Afferent Information Processing in Patients With Chronic Alcoholism. An Evoked Potential Study H.-M. MEINCK, 1 K. RADER,* G. W I E D I T Z A N D L. A D L E R *
Departments of Clinical Neurophysiology and *Psychiatry, University of GOttingen, FRG R e c e i v e d 5 July 1988; A c c e p t e d 30 N o v e m b e r 1989
MEINCK, H.-M., K. RADER, G. WIEDITZ AND L. ADLER. Afferent informationprocessing in patients with chronicalcoholism. An evokedpotential study. ALCOHOL 7(4) 311-313, 1990.--Visual evoked potentials (VEP), median nerve sensory conduction velocity (SNCV) as well as sensory evoked potentials (SEP), and brainstem acoustic evoked potentials (BAEP) were investigated on both sides in 40 patients with chronic alcoholism (mean age 37 years) without clinical signs of alcohol-induced central nervous system lesions. The results were compared to those obtained in 40 normal controls (mean age 32 years). In both groups, the parameters were analysed by means of both dependence and interdependence statistics. Dependence statistics (ANOVA) revealed significant differences between both groups. In 70% of the patients, at least one pathological parameter (>mean ± 2.5 SD) was found; about 38% of the patients had two or more pathological values. Most pathological parameters were observed with BAEP testing (45% of patients) followed by SNCV (33%), median nerve SEP (30%), and VEP (10%). No significant clustering of pathological parameters was found in certain patients. By means of interdependence statistics, evidence is presented for a disturbance of sensory processing in the brainstem auditory pathways of the patients. Alcoholism
Evoked potentials
Sensory processing
AN increased incidence of abnormal evoked potentials (EPs) is well established in patients suffering from chronic alcoholism (1--6, 9, 11, 12). However, not only the mechanism, but also the specificity and site of the alcohol-induced disturbances of afferent information processing are, at present, speculative. The aim of the present study was to find out whether a) there exists a differential vulnerability of afferent pathways to alcohol, and b) there is any clustering of abnormal EPs among individual patients which possibly might indicate a higher risk for alcohol-induced syndromes of central nervous system (CNS) lesions. Some preliminary results have been published elsewhere (15).
neurological or mental disorders (including substantial head trauma) except for polyneuropathy (n = 21), delirium tremens (n = 13), and seizures in withdrawal (n = 12) were excluded. The electrophysiological findings were compared to those obtained from 40 normal unmatched controls, 17 males and 23 females, all staff members or medical students, aged 3 2 -+ 10 years. Control subjects were known from personal contact with the authors to be either abstinent or nondependent occasional alcohol consumers. Visual evoked potentials (VEP), median nerve somatosensory evoked potentials (SEP) and brainstem acoustic evoked potentials (BAEP) as well as antidromic median nerve sensory conduction velocity (SNCV) were investigated on both sides using routine procedures. The VEP was evoked by repetitive reversal (1.7/sec) of a checkerboard pattern projected via a mirror on a screen [cf. (9)], and was recorded from O z - C z with surface electrodes (200 sweeps summated). The SEP was evoked by rectangular pulses (0.1 msec, 5 to 15 rnA, stimulus frequency 2.7/sec, summation of 500 stimuli) and recorded from C3'/C4' to Fz (filter: 20-1000 Hz). SEP latencies were corrected for body height. The BAEPs were elicited by monaural application of a damped rarefaction-condensation sinus tone via earphones (duration 0.1 msec, stimulus frequency 11.3/sec, stimulus intensity 90 dB above hearing level, summation of 2000 responses) and recorded from between the ipsilateral mastoid and the vertex (filter: 100-3000 Hz). The
METHOD Forty-four consecutive male patients aged 37-+ 9 years were studied 1-5 weeks (mean: 2 weeks) after alcohol withdrawal. Patients were not investigated until they were detoxified from drugs (clomethiazol, diazepam, carbamazepine) and were free of their symptoms for at least three days. At the time of investigation the individual duration of alcohol dependence ranged between 1 and 25 (mean: 14.7-+6.2 SD) years. All patients met at least one first-level criterion for the diagnosis of alcoholism (10), most often seizures in withdrawal or delirium tremens. All except four belonged to the gamma-type of alcoholism (6). Patients with past or present drug abuse or with ophthalmological, otological,
~Requests for reprints should be addressed to Prof. Dr. H.-M. Meinck, Neurologische Universit/itsklinik, Im Neuenheimer Feld 400, D-6900 Heidelberg, FRG.
311
312
MEINCK, R.~DER, WIEDITZ AND ADLER
VEP
excluded from this study because of variability of EP (particularly BAEP) latencies greater than 5%. Results of EP testing were accepted as abnormal if the individual latencies were longer than m e a n - 2.5 SD of the control group. The shortest EP latencies from each subject were considered for statistical analysis. The neurophysiological parameters were pooled in a data bank, corrected for gender and age, and further calculations were performed on an Univac 1180 using Dixon's BMDP (7). The following subprograms were applied: 2V (variance analysis), 4M (factor analysis), and 3D (t-test).
SEP ~ormal A
I
10 tJV ~
~
-
RESULTS
6
lbom
~5 ms
BAEP
/ 0.3uV
,,~
.
FIG. 1. Specimen recordings of the visual (VEP), median nerve somatosensory (SEP), and brainstem acoustic evoked potentials (BAEP) from normal subjects and chronic alcoholic patients. Vertical and horizontal calibrations are identical for each pair of registrations.
SNCV was determined by means of stimulating the median nerve at the wrist (stimulus duration 0.1 msec, 10--15 mA, cathode distal) and recording of the antidromic nerve action potential from the index finger with ring electrodes. Each neurophysiological test was repeated at least once, and the recordings were accepted only if the intertest variation was less than 5%. Four patients were
Some specimen recordings of multimodality evoked potentials in both patients and controls are shown in Fig. 1, and the principal results of this study are presented in Table 1: The mean values of almost all parameters were delayed in the patient group (N = 40). On the whole, 16 patients had normal EPs, 15 patients had one pathological EP, and 9 patients had two pathological EPs. If the SNCV was additionally considered, entirely normal results were obtained from 12 patients; 13 patients had one, 11 patients had two, and 4 patients had three abnormal tests. With regard to the individual tests, the BAEP was most sensitive (18 patients = 45%; the individual BAEP components being delayed with about the same incidence) followed by the SNCV (13 patients = 33%), the SEP (12 patients = 30%), and the VEP (4 patients = 10%). Comparison of the median nerve SNCV and SEP data showed that only 5 of 15 delayed SEPs were associated with (and thus attributable to) a delayed SNCV. Correspondingly, the presence of clinical polyneuropathy was not significantly associated with delayed EPs of either modality. Interdependence statistical analysis of the data (product moment correlation) revealed significant correlations between the latencies of the individual BAEP components and the SEP (p
0741-8329/90 $3.00 + .00
Afferent Information Processing in Patients With Chronic Alcoholism. An Evoked Potential Study H.-M. MEINCK, 1 K. RADER,* G. W I E D I T Z A N D L. A D L E R *
Departments of Clinical Neurophysiology and *Psychiatry, University of GOttingen, FRG R e c e i v e d 5 July 1988; A c c e p t e d 30 N o v e m b e r 1989
MEINCK, H.-M., K. RADER, G. WIEDITZ AND L. ADLER. Afferent informationprocessing in patients with chronicalcoholism. An evokedpotential study. ALCOHOL 7(4) 311-313, 1990.--Visual evoked potentials (VEP), median nerve sensory conduction velocity (SNCV) as well as sensory evoked potentials (SEP), and brainstem acoustic evoked potentials (BAEP) were investigated on both sides in 40 patients with chronic alcoholism (mean age 37 years) without clinical signs of alcohol-induced central nervous system lesions. The results were compared to those obtained in 40 normal controls (mean age 32 years). In both groups, the parameters were analysed by means of both dependence and interdependence statistics. Dependence statistics (ANOVA) revealed significant differences between both groups. In 70% of the patients, at least one pathological parameter (>mean ± 2.5 SD) was found; about 38% of the patients had two or more pathological values. Most pathological parameters were observed with BAEP testing (45% of patients) followed by SNCV (33%), median nerve SEP (30%), and VEP (10%). No significant clustering of pathological parameters was found in certain patients. By means of interdependence statistics, evidence is presented for a disturbance of sensory processing in the brainstem auditory pathways of the patients. Alcoholism
Evoked potentials
Sensory processing
AN increased incidence of abnormal evoked potentials (EPs) is well established in patients suffering from chronic alcoholism (1--6, 9, 11, 12). However, not only the mechanism, but also the specificity and site of the alcohol-induced disturbances of afferent information processing are, at present, speculative. The aim of the present study was to find out whether a) there exists a differential vulnerability of afferent pathways to alcohol, and b) there is any clustering of abnormal EPs among individual patients which possibly might indicate a higher risk for alcohol-induced syndromes of central nervous system (CNS) lesions. Some preliminary results have been published elsewhere (15).
neurological or mental disorders (including substantial head trauma) except for polyneuropathy (n = 21), delirium tremens (n = 13), and seizures in withdrawal (n = 12) were excluded. The electrophysiological findings were compared to those obtained from 40 normal unmatched controls, 17 males and 23 females, all staff members or medical students, aged 3 2 -+ 10 years. Control subjects were known from personal contact with the authors to be either abstinent or nondependent occasional alcohol consumers. Visual evoked potentials (VEP), median nerve somatosensory evoked potentials (SEP) and brainstem acoustic evoked potentials (BAEP) as well as antidromic median nerve sensory conduction velocity (SNCV) were investigated on both sides using routine procedures. The VEP was evoked by repetitive reversal (1.7/sec) of a checkerboard pattern projected via a mirror on a screen [cf. (9)], and was recorded from O z - C z with surface electrodes (200 sweeps summated). The SEP was evoked by rectangular pulses (0.1 msec, 5 to 15 rnA, stimulus frequency 2.7/sec, summation of 500 stimuli) and recorded from C3'/C4' to Fz (filter: 20-1000 Hz). SEP latencies were corrected for body height. The BAEPs were elicited by monaural application of a damped rarefaction-condensation sinus tone via earphones (duration 0.1 msec, stimulus frequency 11.3/sec, stimulus intensity 90 dB above hearing level, summation of 2000 responses) and recorded from between the ipsilateral mastoid and the vertex (filter: 100-3000 Hz). The
METHOD Forty-four consecutive male patients aged 37-+ 9 years were studied 1-5 weeks (mean: 2 weeks) after alcohol withdrawal. Patients were not investigated until they were detoxified from drugs (clomethiazol, diazepam, carbamazepine) and were free of their symptoms for at least three days. At the time of investigation the individual duration of alcohol dependence ranged between 1 and 25 (mean: 14.7-+6.2 SD) years. All patients met at least one first-level criterion for the diagnosis of alcoholism (10), most often seizures in withdrawal or delirium tremens. All except four belonged to the gamma-type of alcoholism (6). Patients with past or present drug abuse or with ophthalmological, otological,
~Requests for reprints should be addressed to Prof. Dr. H.-M. Meinck, Neurologische Universit/itsklinik, Im Neuenheimer Feld 400, D-6900 Heidelberg, FRG.
311
312
MEINCK, R.~DER, WIEDITZ AND ADLER
VEP
excluded from this study because of variability of EP (particularly BAEP) latencies greater than 5%. Results of EP testing were accepted as abnormal if the individual latencies were longer than m e a n - 2.5 SD of the control group. The shortest EP latencies from each subject were considered for statistical analysis. The neurophysiological parameters were pooled in a data bank, corrected for gender and age, and further calculations were performed on an Univac 1180 using Dixon's BMDP (7). The following subprograms were applied: 2V (variance analysis), 4M (factor analysis), and 3D (t-test).
SEP ~ormal A
I
10 tJV ~
~
-
RESULTS
6
lbom
~5 ms
BAEP
/ 0.3uV
,,~
.
FIG. 1. Specimen recordings of the visual (VEP), median nerve somatosensory (SEP), and brainstem acoustic evoked potentials (BAEP) from normal subjects and chronic alcoholic patients. Vertical and horizontal calibrations are identical for each pair of registrations.
SNCV was determined by means of stimulating the median nerve at the wrist (stimulus duration 0.1 msec, 10--15 mA, cathode distal) and recording of the antidromic nerve action potential from the index finger with ring electrodes. Each neurophysiological test was repeated at least once, and the recordings were accepted only if the intertest variation was less than 5%. Four patients were
Some specimen recordings of multimodality evoked potentials in both patients and controls are shown in Fig. 1, and the principal results of this study are presented in Table 1: The mean values of almost all parameters were delayed in the patient group (N = 40). On the whole, 16 patients had normal EPs, 15 patients had one pathological EP, and 9 patients had two pathological EPs. If the SNCV was additionally considered, entirely normal results were obtained from 12 patients; 13 patients had one, 11 patients had two, and 4 patients had three abnormal tests. With regard to the individual tests, the BAEP was most sensitive (18 patients = 45%; the individual BAEP components being delayed with about the same incidence) followed by the SNCV (13 patients = 33%), the SEP (12 patients = 30%), and the VEP (4 patients = 10%). Comparison of the median nerve SNCV and SEP data showed that only 5 of 15 delayed SEPs were associated with (and thus attributable to) a delayed SNCV. Correspondingly, the presence of clinical polyneuropathy was not significantly associated with delayed EPs of either modality. Interdependence statistical analysis of the data (product moment correlation) revealed significant correlations between the latencies of the individual BAEP components and the SEP (p
