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Visual evoked potentials in chronic alcoholism
Addictive Behaviors 32 (2007) 1470 – 1473
Short communication
Visual evoked potentials in chronic alcoholism Bijen Nazliel ⁎, Zehra Arikan, Ceyla İrkec Gazi University Faculty of Medicine Department of Neurology and Psychiatry, Ankara, Turkey
Abstract In order to evaluate the effect of alcohol consumption and the effect of abstinence on central nervous system generated parameters, we performed pattern visual evoked potential (PVEP) recordings on chronic alcoholics. The study was conducted on forty patients diagnosed as chronic alcoholics according to DSM IV criteria. They were aged mean: 42, and had histories of alcohol abuse for at least six years (mean: 21). 15% of the patients demonstrated abnormal VEP results at least in one tested eye. In order to test the effect of abstinence period on P100 latency values, alcoholics were divided in to two subgroups. Group I (Gr I) consisted twenty-four alcoholics who had been abstinent for less than thirty days (mean: 14), and Group II (Gr II) consisted sixteen alcoholics who had been abstinent for more than thirty and less than seventy-six days (mean: 38) The mean P100 latency of Gr I and Gr II was 101 and 102 milliseconds (ms) respectively; and when compared to normal controls the difference was statistically significant ( p: 0.016, p: 0.009). Abnormal VEP in asymptomatic chronic alcoholics suggests that they may be useful in the detection of early changes and in following the progress of patients with the disorder. © 2006 Elsevier Ltd. All rights reserved. Keywords: Chronic alcoholism; Pattern visual evoked potential (PVEP); P100 amplitude; P100 latency
1. Introduction The chronic consumption of alcohol leads to alteration in the central nervous system (CNS), though many patients do not show any other clinical signs than those proper to the alcoholism, especially if they are young or in the initial stages of the illness (Cadeveria, Grau, Roso, & Sanchez-Turet, 1991). However numerous biomedical studies have reported alterations in the central nervous system (CNS) structures and
⁎ Corresponding author. Tunali Hilmi Caddesi 34/10 Kavaklidere, Ankara, Turkey. Fax: +90 312 4182175. E-mail address: [email protected] (B. Nazliel). 0306-4603/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.addbeh.2006.09.006
B. Nazliel et al. / Addictive Behaviors 32 (2007) 1470–1473
1471
functions in alcoholics (Cadeveria, Coraminas, Holguin, Turet, & Grau, 1994; Chan, McLeod, Tuck, Walsh, & Feary, 1986). Even in patients who are clinically only slightly affected, structural and functional alterations can be detected by neuroradiological and neurophysiological methods (Cadeveria et al., 1991). Since the late 1970s functional nervous system degeneration in chronic alcoholics has been investigated by means of evoked potentials (EP) (Diaz, Cadeveria, & Grau, 1990). EP like visual evoked potentials (VEP) provide objective information on the functional integrity of CNS structures and find their greatest clinical use in diagnosis of demyelinating, brainstem, metabolic or sensory organ disease (Brown, Sufit, & Sollinger, 1987; Derici et al., 2003; Irkec, Nazlıel, & Kocer, 2001; Nazliel et al., 2002). In order to evaluate the effect of alcohol consumption and the effect of abstinence on central nervous system generated parameters, we performed pattern VEP (PVEP) recordings on chronic alcoholics. 2. Materials and methods The study was conducted on 40 hospitalized male patients diagnosed as chronic alcoholics according to DSM-IV criteria. Their age range was from twenty-nine to sixty-one years (mean: 42 ± 6). The subjects had histories of alcohol abuse for at least six years (mean: 21 ± 9). At the time of recording, subjects had undergone detoxification treatment for at least seven days (mean = 24) therefore withdrawal linked hypothermia was ruled out as an unlikely concomitant factor. Detoxification had been tested by using alcohol meter everyday. All of them were smoking cigarettes ranging from ten to sixty per day (mean: 26). During testing all patients were seated in a semidarkened room with the stimulus presented on a television monitor 1 meter (m) from the tested eye. Viewing was central and monoocular. Untested eyes were patched. Recordings were performed using Nihon Kohden/Neuropack EMG machine with an analysis time of 500 ms and a sweep speed of 50 ms/s. Low and high frequency filter settings was 1.0 Hz and 100 Hz respectively. Monopolar platinum needle electrodes (Medtronic 22G × 10 mm) placed on the scalp (OZ-FZ) according to 10–20 system were used for recording. In each recording session electrode-to-skin impedance was less than 5 kiloohms (kΩ). The ground electrode was on the forearm. VEP were obtained by monocular checkerboard pattern reversal stimulation as described by our previous study.(Nazliel et al., 2002). The control group consisted from twenty-five male subjects (mean age: 41.0 ± 12) who attended the EMG laboratory with a prediagnosis of carpal tunnel syndrome, whose nerve conduction studies found out to be normal. 3. Statistical evaluation The soft ware used for statistical evaluation was SPSS 10.0 statistical package program. Results are expressed as mean ± SD. Independent-samples T test was used to compare differences between groups and one-way ANOVA was used to compare differences with in groups. A P value of less than 0.05 was considered to be significant. 4. Results The response to pattern stimulation in the normal subjects was a triphasic response with a prominent positive wave P100 with a peak latency of 90–108 ms mean: 97.3 ± 5.5 ms. The major positive wave P100
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B. Nazliel et al. / Addictive Behaviors 32 (2007) 1470–1473
was downward peak in the record when either eye was stimulated. The mean peak amplitude was 10.2 ± 3.7 microvolts (μV) In the alcoholic group mean P100 latency was 101 ± 9 (range: 89–130) ms and mean P100 amplitude was 10.4 ± 4.5 μV (range: 2.60–25.30). And the difference between the two groups for P100 latency was (p = 0.004 CI(95%): −7.548; −1.461) and for P100 amplitude was not (p = 0.7 CI(95%): −1.732; 1.292) statistically signif icant. In order to test the effect of abstinence period on P100 latency values; alcoholics were divided in to two subgroups. Group I consisted 24 alcoholics who had been abstinent for less than 30 days (range = 7–28, mean = 14) and Group II consisted 16 chronic alcoholics who had been abstinent for more than 30 and less than 76 days (mean = 38). The mean P100 latency of Gr I and Gr II was 101 and 102 ms respectively; and the difference between these two subgroups was not statistically significant (p = 0.6 CI(95%) −5.127; 3.231). When the P100 latency of these subgroups (Gr I, Gr II) were compared to the normal controls like in the total group the difference was statistically significant (p = 0.016 CI(95%) −8.276; −0.875 and p = 0.009 CI(95%) −9.669; −1.377 respectively). The P100 amplitudes of these two subgroups respectively did not significantly differ from those of normal controls (p = 0.1 CI(95%) −2.914; 0.560 and p = 0.2 CI(95%) −1.034; 2.859 respectively). In order to analyze the data of the patients individually we defined a criteria for abnormality. Criteria for defining an abnormal VEP were: a. Latency to the major positive peak (P100) greater than 3 standard deviations (SD) above the mean for control subjects (97 ± 5: 112 ms) b. An absent unilateral or bilateral response c. The amplitude of the VEP is more variable than its latency and it is difficult to establish abnormality unless it is reduced to less than 2 μV or there is a marked difference between the two sides. Because of this, the amplitude of P100 is not considered as a major index of an abnormality. According to the defined criteria six patients (15%) demonstrated abnormal results. Four (10%) of them were in Gr I and 2 (5%) of them were in Gr II. One patient from each group had P100 latency prolongation in both eyes. In the remaining four prolonged P100 latency was present only on one tested eye. Mean latency (r: −0.291, p: 0.069) and amplitude (r: −0.229, p: 0.156) of P100 did not correlate with the mean duration of alcohol abuse and neither with mean time of abstinence from alcohol consumption (r: −0.065, p: 0.692 and r: −0.097, p: 0.550 respectively). 5. Discussion We performed this study to examine the effect of alcohol consumption on PVEP parameters in a selected and described alcoholic sample in a relatively short period of detoxified state in order to test the relation ship between alcohol consumption and stage of detoxification; defined as days of abstinence prior to the recording session. 15% of our patients demonstrated abnormal results in at least one tested eye. P100 latency of alcoholics in our group differed significantly from those of normal controls. Latency in two subgroups of alcoholics formed according to the mean time of abstinence prior to recording session showed that alcoholics continue to have a pathological response up to seventy-five days of abstinence. P100 values were pathologic both in acutely (mean: 14 days) and sub acutely detoxified patients (mean:
B. Nazliel et al. / Addictive Behaviors 32 (2007) 1470–1473
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38 days). Amplitude and latency of P100 did not correlate with the mean duration of alcohol abuse and neither with mean time of abstinence from alcohol consumption. Postuma and Ahmed reported abnormal results respectively in 15% and 13% of patients they studied (Ahmed & Hines, 1983; Postuma & Visser, 1982). Chan and McLead performed VEP recordings in alcoholics who had been abstained for a mean of twenty-two days and found abnormal results in 23% of patients they studied (Chan et al., 1986; Postuma & Visser, 1982). There was a prolongation of the latency and reduction of the amplitude of the P100 component for the whole group. Compared to control subjects, Nicolas et al. showed that chronic alcoholics exhibited a significant prolongation of the P100 latency of visual evoked potentials and related them to the life time dose of ethanol consumed (Nicolas et al., 1997). P100 latency prolongation in alcoholics may be due to various factors. These include demyelization, probably as a result of electrolytic disturbances, changes in membrane properties and changes in gross or fine neuronal structure. There are great differences in terms of individual susceptibility to alcohol, and abnormal VEPs in visually asymptomatic alcoholic patients suggests that there might be a subclinical form of alcohol ampliopia (Chan et al., 1986). Finding abnormal VEP in patients with alcohol-related brain damage suggests that they may be useful in the detection of early changes and in following the progress of patients with the disorder. Long term follow-up studies are needed to learn how and when these abnormalities normalize. References Ahmed, I., & Hines, K. S. (1983). Visual evoked potentials in alcoholics. Clinical Electroencephalography, 14, 17−19. Brown, J. J., Sufit, R. L., & Sollinger, H. W. (1987). Visual evoked potentials following renal transplantation. Electroencephalography and Clinical Neurophysiology, 66, 101−107. Cadeveria, F., Coraminas, M., Holguin, S., Turet, M., & Grau, C. (1994). Reversibility of brainstem evoked potentials abnormalities in abstinent chronic alcoholics: One year follow-up. Electroencephalography and Clinical Neurophysiology, 90, 450−455. Cadeveria, F., Grau, C., Roso, & Sanchez-Turet, M. (1991). Multimodality exploration of event-related potentials in chronic alcoholics. Alcoholism, Clinical and Experimental Research, 15, 607−611. Chan, Y. W., McLeod, J. G., Tuck, R. R., Walsh, J. C., & Feary, P. A. (1986). Visual evoked potential responses in chronic alcoholics. Journal of Neurology, Neurosurgery and Psychiatry, 49, 945−950. Derici, U., Nazlıel, B., Irkec, C., Sindel, S., Arınsoy, T., & Bali, M. (2003). Effect of hemodialysis on visual evoked potential parameters. Nephrology, 8(1), 11−15. Diaz, F., Cadeveria, A. F., & Grau, C. (1990). Short- and middle-latency evoked potentials in abstinent chronic alcoholics: Preliminary f indings. Electroencephalography and Clinical Neurophysiology, 77, 145−150. Irkec, C., Nazlıel, B., & Kocer, B. (2001). The correlation between cerebrospinal f luid f indings and evoked potentials during an acute MS attack. Electromyography and Clinical Neurophysiology, 41(2), 117−1221. Nazliel, B., Akcay, E., Irkec, C., Yetkin, I., Ersoy, R., & Toruner, F. (2002). Pattern visual potential evaluation (PVEP) evaluation in hypothyroidism. Journal of Endocrinological Investigation, 25, 955−958. Nicolas, J. M, Estruch, R., Salemero, M., Orteu, N., Fernandez-Sola, J., Sacanella, E., et al. (1997). Brain impairment in wellnourished chronics is related to ethanol intake. Annals of Neurology, 41, 559−598. Postuma, J., & Visser, S. L. (1982). Visual evoked potentials and alcohol induced brain damage. In J. Courjon, P. Mauguire, & M. Revol (Eds.), Clinical applications of evoked potentials in neurology (pp. 141−149). New York: Raven Press.
Short communication
Visual evoked potentials in chronic alcoholism Bijen Nazliel ⁎, Zehra Arikan, Ceyla İrkec Gazi University Faculty of Medicine Department of Neurology and Psychiatry, Ankara, Turkey
Abstract In order to evaluate the effect of alcohol consumption and the effect of abstinence on central nervous system generated parameters, we performed pattern visual evoked potential (PVEP) recordings on chronic alcoholics. The study was conducted on forty patients diagnosed as chronic alcoholics according to DSM IV criteria. They were aged mean: 42, and had histories of alcohol abuse for at least six years (mean: 21). 15% of the patients demonstrated abnormal VEP results at least in one tested eye. In order to test the effect of abstinence period on P100 latency values, alcoholics were divided in to two subgroups. Group I (Gr I) consisted twenty-four alcoholics who had been abstinent for less than thirty days (mean: 14), and Group II (Gr II) consisted sixteen alcoholics who had been abstinent for more than thirty and less than seventy-six days (mean: 38) The mean P100 latency of Gr I and Gr II was 101 and 102 milliseconds (ms) respectively; and when compared to normal controls the difference was statistically significant ( p: 0.016, p: 0.009). Abnormal VEP in asymptomatic chronic alcoholics suggests that they may be useful in the detection of early changes and in following the progress of patients with the disorder. © 2006 Elsevier Ltd. All rights reserved. Keywords: Chronic alcoholism; Pattern visual evoked potential (PVEP); P100 amplitude; P100 latency
1. Introduction The chronic consumption of alcohol leads to alteration in the central nervous system (CNS), though many patients do not show any other clinical signs than those proper to the alcoholism, especially if they are young or in the initial stages of the illness (Cadeveria, Grau, Roso, & Sanchez-Turet, 1991). However numerous biomedical studies have reported alterations in the central nervous system (CNS) structures and
⁎ Corresponding author. Tunali Hilmi Caddesi 34/10 Kavaklidere, Ankara, Turkey. Fax: +90 312 4182175. E-mail address: [email protected] (B. Nazliel). 0306-4603/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.addbeh.2006.09.006
B. Nazliel et al. / Addictive Behaviors 32 (2007) 1470–1473
1471
functions in alcoholics (Cadeveria, Coraminas, Holguin, Turet, & Grau, 1994; Chan, McLeod, Tuck, Walsh, & Feary, 1986). Even in patients who are clinically only slightly affected, structural and functional alterations can be detected by neuroradiological and neurophysiological methods (Cadeveria et al., 1991). Since the late 1970s functional nervous system degeneration in chronic alcoholics has been investigated by means of evoked potentials (EP) (Diaz, Cadeveria, & Grau, 1990). EP like visual evoked potentials (VEP) provide objective information on the functional integrity of CNS structures and find their greatest clinical use in diagnosis of demyelinating, brainstem, metabolic or sensory organ disease (Brown, Sufit, & Sollinger, 1987; Derici et al., 2003; Irkec, Nazlıel, & Kocer, 2001; Nazliel et al., 2002). In order to evaluate the effect of alcohol consumption and the effect of abstinence on central nervous system generated parameters, we performed pattern VEP (PVEP) recordings on chronic alcoholics. 2. Materials and methods The study was conducted on 40 hospitalized male patients diagnosed as chronic alcoholics according to DSM-IV criteria. Their age range was from twenty-nine to sixty-one years (mean: 42 ± 6). The subjects had histories of alcohol abuse for at least six years (mean: 21 ± 9). At the time of recording, subjects had undergone detoxification treatment for at least seven days (mean = 24) therefore withdrawal linked hypothermia was ruled out as an unlikely concomitant factor. Detoxification had been tested by using alcohol meter everyday. All of them were smoking cigarettes ranging from ten to sixty per day (mean: 26). During testing all patients were seated in a semidarkened room with the stimulus presented on a television monitor 1 meter (m) from the tested eye. Viewing was central and monoocular. Untested eyes were patched. Recordings were performed using Nihon Kohden/Neuropack EMG machine with an analysis time of 500 ms and a sweep speed of 50 ms/s. Low and high frequency filter settings was 1.0 Hz and 100 Hz respectively. Monopolar platinum needle electrodes (Medtronic 22G × 10 mm) placed on the scalp (OZ-FZ) according to 10–20 system were used for recording. In each recording session electrode-to-skin impedance was less than 5 kiloohms (kΩ). The ground electrode was on the forearm. VEP were obtained by monocular checkerboard pattern reversal stimulation as described by our previous study.(Nazliel et al., 2002). The control group consisted from twenty-five male subjects (mean age: 41.0 ± 12) who attended the EMG laboratory with a prediagnosis of carpal tunnel syndrome, whose nerve conduction studies found out to be normal. 3. Statistical evaluation The soft ware used for statistical evaluation was SPSS 10.0 statistical package program. Results are expressed as mean ± SD. Independent-samples T test was used to compare differences between groups and one-way ANOVA was used to compare differences with in groups. A P value of less than 0.05 was considered to be significant. 4. Results The response to pattern stimulation in the normal subjects was a triphasic response with a prominent positive wave P100 with a peak latency of 90–108 ms mean: 97.3 ± 5.5 ms. The major positive wave P100
1472
B. Nazliel et al. / Addictive Behaviors 32 (2007) 1470–1473
was downward peak in the record when either eye was stimulated. The mean peak amplitude was 10.2 ± 3.7 microvolts (μV) In the alcoholic group mean P100 latency was 101 ± 9 (range: 89–130) ms and mean P100 amplitude was 10.4 ± 4.5 μV (range: 2.60–25.30). And the difference between the two groups for P100 latency was (p = 0.004 CI(95%): −7.548; −1.461) and for P100 amplitude was not (p = 0.7 CI(95%): −1.732; 1.292) statistically signif icant. In order to test the effect of abstinence period on P100 latency values; alcoholics were divided in to two subgroups. Group I consisted 24 alcoholics who had been abstinent for less than 30 days (range = 7–28, mean = 14) and Group II consisted 16 chronic alcoholics who had been abstinent for more than 30 and less than 76 days (mean = 38). The mean P100 latency of Gr I and Gr II was 101 and 102 ms respectively; and the difference between these two subgroups was not statistically significant (p = 0.6 CI(95%) −5.127; 3.231). When the P100 latency of these subgroups (Gr I, Gr II) were compared to the normal controls like in the total group the difference was statistically significant (p = 0.016 CI(95%) −8.276; −0.875 and p = 0.009 CI(95%) −9.669; −1.377 respectively). The P100 amplitudes of these two subgroups respectively did not significantly differ from those of normal controls (p = 0.1 CI(95%) −2.914; 0.560 and p = 0.2 CI(95%) −1.034; 2.859 respectively). In order to analyze the data of the patients individually we defined a criteria for abnormality. Criteria for defining an abnormal VEP were: a. Latency to the major positive peak (P100) greater than 3 standard deviations (SD) above the mean for control subjects (97 ± 5: 112 ms) b. An absent unilateral or bilateral response c. The amplitude of the VEP is more variable than its latency and it is difficult to establish abnormality unless it is reduced to less than 2 μV or there is a marked difference between the two sides. Because of this, the amplitude of P100 is not considered as a major index of an abnormality. According to the defined criteria six patients (15%) demonstrated abnormal results. Four (10%) of them were in Gr I and 2 (5%) of them were in Gr II. One patient from each group had P100 latency prolongation in both eyes. In the remaining four prolonged P100 latency was present only on one tested eye. Mean latency (r: −0.291, p: 0.069) and amplitude (r: −0.229, p: 0.156) of P100 did not correlate with the mean duration of alcohol abuse and neither with mean time of abstinence from alcohol consumption (r: −0.065, p: 0.692 and r: −0.097, p: 0.550 respectively). 5. Discussion We performed this study to examine the effect of alcohol consumption on PVEP parameters in a selected and described alcoholic sample in a relatively short period of detoxified state in order to test the relation ship between alcohol consumption and stage of detoxification; defined as days of abstinence prior to the recording session. 15% of our patients demonstrated abnormal results in at least one tested eye. P100 latency of alcoholics in our group differed significantly from those of normal controls. Latency in two subgroups of alcoholics formed according to the mean time of abstinence prior to recording session showed that alcoholics continue to have a pathological response up to seventy-five days of abstinence. P100 values were pathologic both in acutely (mean: 14 days) and sub acutely detoxified patients (mean:
B. Nazliel et al. / Addictive Behaviors 32 (2007) 1470–1473
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38 days). Amplitude and latency of P100 did not correlate with the mean duration of alcohol abuse and neither with mean time of abstinence from alcohol consumption. Postuma and Ahmed reported abnormal results respectively in 15% and 13% of patients they studied (Ahmed & Hines, 1983; Postuma & Visser, 1982). Chan and McLead performed VEP recordings in alcoholics who had been abstained for a mean of twenty-two days and found abnormal results in 23% of patients they studied (Chan et al., 1986; Postuma & Visser, 1982). There was a prolongation of the latency and reduction of the amplitude of the P100 component for the whole group. Compared to control subjects, Nicolas et al. showed that chronic alcoholics exhibited a significant prolongation of the P100 latency of visual evoked potentials and related them to the life time dose of ethanol consumed (Nicolas et al., 1997). P100 latency prolongation in alcoholics may be due to various factors. These include demyelization, probably as a result of electrolytic disturbances, changes in membrane properties and changes in gross or fine neuronal structure. There are great differences in terms of individual susceptibility to alcohol, and abnormal VEPs in visually asymptomatic alcoholic patients suggests that there might be a subclinical form of alcohol ampliopia (Chan et al., 1986). Finding abnormal VEP in patients with alcohol-related brain damage suggests that they may be useful in the detection of early changes and in following the progress of patients with the disorder. Long term follow-up studies are needed to learn how and when these abnormalities normalize. References Ahmed, I., & Hines, K. S. (1983). Visual evoked potentials in alcoholics. Clinical Electroencephalography, 14, 17−19. Brown, J. J., Sufit, R. L., & Sollinger, H. W. (1987). Visual evoked potentials following renal transplantation. Electroencephalography and Clinical Neurophysiology, 66, 101−107. Cadeveria, F., Coraminas, M., Holguin, S., Turet, M., & Grau, C. (1994). Reversibility of brainstem evoked potentials abnormalities in abstinent chronic alcoholics: One year follow-up. Electroencephalography and Clinical Neurophysiology, 90, 450−455. Cadeveria, F., Grau, C., Roso, & Sanchez-Turet, M. (1991). Multimodality exploration of event-related potentials in chronic alcoholics. Alcoholism, Clinical and Experimental Research, 15, 607−611. Chan, Y. W., McLeod, J. G., Tuck, R. R., Walsh, J. C., & Feary, P. A. (1986). Visual evoked potential responses in chronic alcoholics. Journal of Neurology, Neurosurgery and Psychiatry, 49, 945−950. Derici, U., Nazlıel, B., Irkec, C., Sindel, S., Arınsoy, T., & Bali, M. (2003). Effect of hemodialysis on visual evoked potential parameters. Nephrology, 8(1), 11−15. Diaz, F., Cadeveria, A. F., & Grau, C. (1990). Short- and middle-latency evoked potentials in abstinent chronic alcoholics: Preliminary f indings. Electroencephalography and Clinical Neurophysiology, 77, 145−150. Irkec, C., Nazlıel, B., & Kocer, B. (2001). The correlation between cerebrospinal f luid f indings and evoked potentials during an acute MS attack. Electromyography and Clinical Neurophysiology, 41(2), 117−1221. Nazliel, B., Akcay, E., Irkec, C., Yetkin, I., Ersoy, R., & Toruner, F. (2002). Pattern visual potential evaluation (PVEP) evaluation in hypothyroidism. Journal of Endocrinological Investigation, 25, 955−958. Nicolas, J. M, Estruch, R., Salemero, M., Orteu, N., Fernandez-Sola, J., Sacanella, E., et al. (1997). Brain impairment in wellnourished chronics is related to ethanol intake. Annals of Neurology, 41, 559−598. Postuma, J., & Visser, S. L. (1982). Visual evoked potentials and alcohol induced brain damage. In J. Courjon, P. Mauguire, & M. Revol (Eds.), Clinical applications of evoked potentials in neurology (pp. 141−149). New York: Raven Press.