Brainstem Auditory Evoked Potentials in Migraine-Evidence of Increased Side Differences During the Pain-Free Interval
H.-R Schlake, K.-H. Grotemeyer, B. Hofferberth, I.W. Husstedt, and S. Wiesner Department of Neurology, University of Münster, Albert-Schweitzer-Strasse 33, D-4400 Münster, Federal Republic of Germany. Reprint requests to: Dr. med. Hans-Peter Schlake, Department of Neurology, University of Münster, Albert-Schweitzer-Str.33, D-4400 Münster, Federal Republic of Germany. Accepted for Publication: December 30, 1989. SYNOPSIS
Brainstem auditory evoked potentials (BAEPs) were recorded in 38 unselected patients (6 m./32 f.; age 18-54 yrs.) with various forms of migraine, during the pain-free interval. The values were compared to those of 50 control persons (18 m./32 f.; age 17-75 yrs.). Peak latencies (PL I-VI), interpeak latencies (IPL I-III, Ill-V, I-V) and side differences of all peaks (D I-VI) were calculated. In contrast to PL's of migraine patients, all PL's of control persons were normally distributed. In 6 migraine patients (2 with basilar migraine) PL's were pathologically delayed. Statistical analysis did not show any significant difference in regard to PL's and IPL's between migraine patients and controls. However, side differences of all peaks (except peak IV, VI) were significantly increased in migraine patients as compared to controls. Our results indicate a slight but permanent impairment of brainstem function in migraine. (Headache 30:129-132, 1990) INTRODUCTION
Evoked potentials have proved to be a sensitive method for the detection of even slight cerebral dysfunction. Various data are available on the recording of visual evoked potentials (VEPs) in migraine.1-8 It appears, that an increase in VEP amplitudes is the most consistent finding in headache-free patients without medication.1-5 Additional investigations have shown abnormalities in somatosensory evoked potentials9,10 as well as in contingent negative variation11 in migraine between attacks. Brainstem auditory evoked potentials (BAEP's) are considered to be a sensitive tool for the assessment of brainstem function in areas traversed by auditory pathways. Only a few investigations, however, have been performed on the recording of BAEPs if migraine. Podoshin et al.12 observed a significant increase in peak latencies and interpeak latencies of BAEP's during migraine attacks, while this finding was not confirmed by Ganji13 in a patient during a basilar migraine attack. Recordings of BAEP's in migraine between attacks have yielded contradictory results.12,14-16 It was the purpose of this study to obtain further information on this subject in migraine patients. In addition to the above investigations, side differences of BAEP's were calculated and compared to those of healthy controls. PATIENTS AND METHODS
BAEPs were recorded in 38 migraine patients, 32 females and 6 males. Mean age was 32.4 ± 12.4 (18-54) years. According to the criteria of the Ad Hoc Committee on the Classification of Headache,17 19 patients were suffering from common migraine and 19 from classic migraine (ophthalmic migraine 8; hemiplegic migraine 7; basilar migraine 4). The BAEP findings were compared to those of 50 healthy controls (18 males/32 females) with a mean age of 29.5 ± 12.6 (17-75) years. All patients were outpatients of the headache clinic of the Dept. of Neurology (University of Münster). They underwent a standardized interview as well as a clinical neurological examination. Patients and controls with a history of otitis media, Meniere's disease, sudden hearing loss or any other otologic and neurologic disorder, were excluded. At the time of investigation all patients were symptom-free and had not taken any medication for at least ten days prior to the investigation. Brainstem auditory evoked potentials (BAEPs). BAEPs were recorded using platinum needle electrodes (Dantec Type 13L70) which were fixed at the vertex and both mastoids. Stimuli generated by 0.1 msec square waves with negative polarity, using a Toennies Era Stimulator were delivered monoaurally through an earphone (Beyer Dynamics DT 48) with contralateral masking. The rate of stimulation was 10/sec. Recordings consisted of the average of two sets of 1250 responses, bandpass 0.2 to 2 KHz, made with a Schwarzer neuroaverager, model Basis 8000; analysis time was 10 msec and stimulus intensity 60 dB SL above the individual threshold of hearing. Based on peak latencies (PL) I-VI of BAEPs, the following parameters were calculated:
-interpeak latencies (IPL): IPL I-III = PL III - PL I IPL III-V = PL V - PL III IPL I-V = PL V - PL I -intraindividual side differences of all peaks (in this paper called "D") D X = 1/2peak X (left side) - peak X (right side)1/2 RESULTS
Statistical analysis of BAEP's in control persons revealed a normal distribution of all PL's and IPL's. As PL's of migraine patients were not normally distributed, statistical comparison was performed using the non-parametric Kolomogorov-Smirnov test for two samples. Table 1 summarizes mean, median, range and standard deviation of absolute BAEP latencies (PL) in controls (11-30) as compared to mean median and range of BAEP's in migraine patients (n = 38). (In migraine patients no standard deviation are given, as the values were not normally distributed.) Statistical analysis did not show any significant differences between both groups. Based on the mean of peak latencies of control persons (PLc) peak latencies of headache patients were considered to be pathologically delayed if exceeding the range of PLc + 2.5 S.D. Pathological BAEP's were obtained in 6 patients with migraine (common migraine: 2; classic migraine: 4, 2 of whom had basilar migraine). Table 2 shows mean, median and range of inter-peak latencies (IPL I-III, Ill-V, I-V) of migraine patients as compared to those of control persons. Based on the IPL's of control persons (IPLc) the IPL's of migraine patients did not exceed the range of IPLc + 2.5 S.D. in any case.
PEAK LATENCIES (msec) I left ear I right ear II left ear II right ear III left ear III right ear IV left ear IV right ear V left ear V right ear VI left ear VI right ear 1)
N1 37 38 37 37 38 38 33 36 38 38 37 37
Mean 1.57 1.57 2.67 2.68 3.72 3.68 4.82 4.80 5.52 5.51 7.01 7.00
Median 1.53 1.52 2.68 2.64 3.67 3.64 4.82 4.82 5.49 5.55 7.14 7.09
Range 1.19 - 2.08 1.33- 2.07 2.17 - 3.48 2.24-3.24 3.34-4.42 3.36-4.21 4.26-5.32 4.26 - 5.35 4.82-6.20 4.98-6.28 6.36-7.85 6.46-7.65
N1 50 50 48 49 50 50 45 43 49 49 45 45
Mean ± S.D. 1.50 ± 0.13 1.52 ± 0.13 2.62 ± 0.17 2.64 ± 0.18 3.69 ± 0.14 3.70 ± 0.14 4.78 ± 0.28 4.81 ± 0.29 5.50 ± 0.29 5.53 ± 0.28 7.14 ± 0.31 7.20 ± 0.29
Median Range 1.51 1.24-1.76 1.53 1.30 - 1.83 2.64 2.14 - 2.88 2.64 2.20-3.07 3.70 3.41-4.01 3.68 3.41-4.00 4.83 4.12-5.59 4.83 4.26 - 5.60 5.48 5.12-6.70 5.48 5.12-6.59 7.10 6.55-7.79 7.15 6.51-7.83
Statistical Analysis Controls/Migraineurs N.S.* N.S.* N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.
The numbers represent the number of patients, whose recordings gave distinct and reproducible results; only these patients are included in the statistical analysis.
*N.S.
= not significant
PEAK LATENCIES (msec) I III left ear I III right ear III V left ear III V right ear I V left ear I V right ear 1)
Table 1 Absolute Values of Peak Latencies (PL) I-VI of BAEPs in Patients with Various Forms of Migraine as Compared to Healthy Controls (n = 50) MIGRAINE BETWEEN ATTACKS CONTROL PERSONS
Table 2 Interpeak Latencies (IPL) I-III, III-V and I-V of BAEPs in Patients with Various Forms of Migraine (n = 38) in Comparison to Healthy Persons (n = 50). MIGRAINE BETWEEN ATTACKS CONTROL PERSONS Statistical N1 37 38 37 38 36 38
Mean 2.16 2.11 1.80 1.83 3.93 3.94
Median 2.16 2.14 1.83 1.83 3.93 3.98
Range 1.84 - 2.46 1.78- 2.52 1.23.2.35 1.43-2.17 3.17-4.42 3.41 - 4.44
N1 50 50 49 49 49 49
Mean ± S.D. 2.18 ± 0.18 2.17 ± 0.17 1.82 ± 0.24 1.83 ± 0.27 4.00 ± 0.32 4.01 ± 0.29
Median Range 2.13 1.83-2.59 2.15 1.81 - 2.70 1.84 1.39 - 3.12 1.80 1.31-3.07 4.05 3.51-5.24 3.96 3.58 - 5.07
Analysis Controls/Migraineurs N.S.* N.S.* N.S. N.S. N.S. N.S.
The numbers represent the number of patients, whose recordings gave distinct and reproducible results; only these patients are included in the statistical analysis.
*N.S.
= not significant
Statistical comparison reveals no significant difference of any interpeak latency between migrainous patients and controls. In Table 3 mean, median and range of side differences of all BAEP peak latencies (D I-VI) are given as compared to those of the control persons. Mean side differences of all BAEP peak latencies (except peak IV and VI) were significantly increased in migraine patients as compared to those of the control group. DISCUSSION
Migraine attacks are frequently associated with phonophobia and vertigo. Bickerstaff18,19 was the first to introduce "basilar artery migraine" as a migraine subtype, which involves the basilar artery territory. This syndrome is characterized by a throbbing occipital headache initiated by various prodromal brain-stem symptoms including vertigo, ataxia, visual loss, bilateral sensory alterations as well as impairment of consciousness. The existence of another syndrome has been described, characterized by attacks of vertigo associated with nystagmus, ataxia and transient disturbances of vestibular function, but without impairment of consciousness. This symptom complex ("benign recurrent vertigo") may represent a migraine variant?20-23 In general, these disturbances are considered to be of transient nature, reflecting a functional vasomotor disturbance in the areas of supply of basilar artery and posterior cerebral arteries. Some authors, however, have suggested permanent alterations of brainstem functions in patients suffering from migraine.24,25 Only a few reports are given in the literature concerning the recording of BAEP's in migraine patients. The investigation of BAEP's during migraine attacks12,13 as well as in pain-free intervals12,14-16 yield contradictory findings. The results observed in the present study are in agreement with those of the majority of other authors,12,14,15 who also did not find any statistically significant alteration of either BAEP latencies or interpeak latencies in symptom-free migraine patients as compared to healthy controls. Considering the few pathological BAEP results obtained in the present investigation, it appears that patients with basilar migraine more frequently show alterations of BAEP's than patients with other types of migraine; a pathological delay of BAEP latencies was observed in two of four investigated patients with the basilar subtype. The present study, however, revealed a significant increase of side differences of peak latencies I, II, III, V in migraine patients in comparison to control persons. Similar results have been reported by Bussone et al.16 who found inter-ear asymmetries of IPL I-V to be more pronounced in patients with migraine (during and between attacks), compared to healthy controls as well as patients with tension headache. The observed side asymmetries may indicate a slight but permanent imbalance of brainstem functions in migraine. This may possibly be due to an alteration of perfusion in the vertebrobasilar system. It also has been demonstrated that evoked potentials are influenced by cerebral metabolism, i.e. catecholaminergic and serotoninergic pathways.26,27 Together with the reported alterations of visual evoked potentials, somatosensory evoked potentials and contingent negative variation in the pain-free interval of migraine, the present findings therefore may be interpreted as a reflection of slight but permanent alterations of neuronal activities in migraine. REFERENCES
1.
Diener HC, Ndosi NK, Koletzki E, Langohr D: Visual evoked potentials in migraine, in Pfaffenrath V, Lundberg PO, Sjaastad O (eds): Updating in Headache. Berlin-Heidelberg-New York, Springer-Verlag, 1985, pp 101-106.
2.
Gawel M, Connolly JF, Clifford Rose F: Migraine patients exhibit abnormalities in the visual evoked potential. Headache 23:49-52, 1983.
3.
Kennard C, Gawel M, Rudolph N de M, Cliffford Rose F: Visual evoked potentials in migraine subjects. Res Clin Stud Headache 6:73-80, 1978.
SIDE DIFFERENCES OF PEAK LATENCIES (sec-6) DI D II D III D IV DV D VI 1)
Table 3 Side Differences (D) of BAEP Peak Latencies I-VI in Patients with Various Forms of Migraine (n = 38) as Compared to Those of Control Persons (n = 50) MIGRAINE BETWEEN ATTACKS CONTROL PERSONS
N1 37 37 38 31 37 37
Mean 9.1 11.2 10.1 10.3 12.1 16.5
Median 5 6 6.5 8 9 11
Range 0-53 0-54 0-47 0-41 0-78 0-93
N1 50 50 50 41 49 44
Mean ± S.D. 4.9 6.7 6.4 13.3 6.5 11.5
Median 3 3 5.5 11 4 3.5
Range 0-20 0-46 0-29 0-42 0-30 0-60
Statistical
Analysis Controls/Migraineurs p < 0.025 p < 0.01 p < 0.05 N.S.* p < 0.025 N.S.
The numbers represent the number of patients, whose recordings gave distinct and reproducible results; only these patients are included in the statistical analysis.
*N.S.
= not significant
4.
Lehtonen JB: Visual evoked potentials for single flashes and flickering light in migraine. Headache 14:1-13, 1974.
5.
Nyrke T, Lang AH: Spectral analysis of visual potentials evoked by sine wave modulated light in migraine. Clin Neurophysiol 53:436-442, 1982.
6.
Raudino F: Visual evoked potential in patients with migraine. Headache 28:531-533, 1988.
7.
Richey ET, Kooi KA, Waggoner RW: Visually evoked potentials in migraine. Electroenceph clin Neurophysiol 21:23-27, 1966.
8.
Marsters JB, Good PA, Mortimer MJ: A diagnostic test for migraine using the visual evoked potential. Headache 28:526-530, 1988.
9.
Milone F, D'Andrea G, Canazi AR, Zanini R: Somatosensory evoked potentials patterns in migraine sufferers. Cephalalgia 5(suppl 3):470-474, 1985.
10.
Montagna P, Zucconi M, Zappia M, Liguori R: Somatosensory evoked potentials in migraine and tension headache. Headache 25:115, 1985.
11.
Maertens de Noordhout A, Timsit-Berthier M, Schoenen J: Contingent negative variation (CNV) in migraineurs before and during prophylactic treatment with beta-blockers. Cephalalgia 5(suppl 3):34-35, 1985.
12.
Podoshin L, Ben-David J, Pratt H, Fradis M, Shaft B, Weller B, Wajsbort J, Zellinger M: Auditory brainstem evoked potentials in patients with migraine. Headache 27:27-29, 1987.
13,
Ganji S: Basilar artery migraine: EEG and evoked potential patterns during acute stage. Headache 26:220-223, 1986.
14.
Battistella PA, Suppiej A, Casara G, Cavinato MS, Olivotto D, Pitassi I, Zachello F: Brainstem auditory evoked potentials (BAEPs) in childhood migraine. Headache 28:204-206, 1988.
15.
Benna P, Bianco C, Costa P, Piazza D, Bergamasco B: Visual evoked potentials and brainstem evoked potentials in migraine and transient ischemia attacks. Cephalalgia 5(suppl 2):53-58, 1985.
16.
Bussone G, Sinatra Me, Boiardi A, La Mantie L, Frediani F, Cocchini F: Brainstem auditory evoked potentials in migraine patients in basal conditions and after chronic flunarizine treatment. Cephalalgia 5(supp12):177-180, 1985.
17.
Ad Hoc Committee on Classification of Headache: Classification of Headache. Arch Neurol 6:173-176, 1962.
18.
Bickerstaff ER: Basilar artery migraine. Lancet 1:15-17, 1961.
19.
Bickerstaff ER: Impairment of consciousness in migraine. Lancet 2:1057-1058, 1961.
20.
Fenichel GM: Migraine as a cause of benign paroxysmal vertigo in childhood. J Pediatr 71:114-116, 1967.
21.
Koehler B: Benign paroxysmal vertigo of childhood: a migraine equivalent. Eur J Pediatr 134:149-151, 1980.
22.
Moretti G, Manzoni GC. Caffarra P, Parma M: "Benign recurrent vertigo" and its connection with migraine. Headache 20:344-346, 1980.
23.
Slater R: Benign recurrent vertigo. J Neurol Neurosurg Psychiat 42:363-367, 1979.
24.
Kayan A, Hood JD: Neuro-otological manifestations of migraine. Brain 107:1123-1142, 1984.
25.
Lance JW, Lambert GA, Goadsby PJ, Duckworth JW: Brainstem influences on the cephalic circulation: experimental data from cat and monkey of relevance to mechanism of migraine. Headache 23:258-265, 1983.
26.
Kangasniemi P, Falck B, Langvik V-A, Hyyppä MT: Levotryptophan treatment in migraine. Headache 18:161-166, 1978.
27.
Schoenen J, Timsit-Berthier M, Timsit M: Correlations between contingent negative variation and plasma levels of catecholamines in headache patients. Cephalalgia 5(suppl 3):480-1985.
H.-R Schlake, K.-H. Grotemeyer, B. Hofferberth, I.W. Husstedt, and S. Wiesner Department of Neurology, University of Münster, Albert-Schweitzer-Strasse 33, D-4400 Münster, Federal Republic of Germany. Reprint requests to: Dr. med. Hans-Peter Schlake, Department of Neurology, University of Münster, Albert-Schweitzer-Str.33, D-4400 Münster, Federal Republic of Germany. Accepted for Publication: December 30, 1989. SYNOPSIS
Brainstem auditory evoked potentials (BAEPs) were recorded in 38 unselected patients (6 m./32 f.; age 18-54 yrs.) with various forms of migraine, during the pain-free interval. The values were compared to those of 50 control persons (18 m./32 f.; age 17-75 yrs.). Peak latencies (PL I-VI), interpeak latencies (IPL I-III, Ill-V, I-V) and side differences of all peaks (D I-VI) were calculated. In contrast to PL's of migraine patients, all PL's of control persons were normally distributed. In 6 migraine patients (2 with basilar migraine) PL's were pathologically delayed. Statistical analysis did not show any significant difference in regard to PL's and IPL's between migraine patients and controls. However, side differences of all peaks (except peak IV, VI) were significantly increased in migraine patients as compared to controls. Our results indicate a slight but permanent impairment of brainstem function in migraine. (Headache 30:129-132, 1990) INTRODUCTION
Evoked potentials have proved to be a sensitive method for the detection of even slight cerebral dysfunction. Various data are available on the recording of visual evoked potentials (VEPs) in migraine.1-8 It appears, that an increase in VEP amplitudes is the most consistent finding in headache-free patients without medication.1-5 Additional investigations have shown abnormalities in somatosensory evoked potentials9,10 as well as in contingent negative variation11 in migraine between attacks. Brainstem auditory evoked potentials (BAEP's) are considered to be a sensitive tool for the assessment of brainstem function in areas traversed by auditory pathways. Only a few investigations, however, have been performed on the recording of BAEPs if migraine. Podoshin et al.12 observed a significant increase in peak latencies and interpeak latencies of BAEP's during migraine attacks, while this finding was not confirmed by Ganji13 in a patient during a basilar migraine attack. Recordings of BAEP's in migraine between attacks have yielded contradictory results.12,14-16 It was the purpose of this study to obtain further information on this subject in migraine patients. In addition to the above investigations, side differences of BAEP's were calculated and compared to those of healthy controls. PATIENTS AND METHODS
BAEPs were recorded in 38 migraine patients, 32 females and 6 males. Mean age was 32.4 ± 12.4 (18-54) years. According to the criteria of the Ad Hoc Committee on the Classification of Headache,17 19 patients were suffering from common migraine and 19 from classic migraine (ophthalmic migraine 8; hemiplegic migraine 7; basilar migraine 4). The BAEP findings were compared to those of 50 healthy controls (18 males/32 females) with a mean age of 29.5 ± 12.6 (17-75) years. All patients were outpatients of the headache clinic of the Dept. of Neurology (University of Münster). They underwent a standardized interview as well as a clinical neurological examination. Patients and controls with a history of otitis media, Meniere's disease, sudden hearing loss or any other otologic and neurologic disorder, were excluded. At the time of investigation all patients were symptom-free and had not taken any medication for at least ten days prior to the investigation. Brainstem auditory evoked potentials (BAEPs). BAEPs were recorded using platinum needle electrodes (Dantec Type 13L70) which were fixed at the vertex and both mastoids. Stimuli generated by 0.1 msec square waves with negative polarity, using a Toennies Era Stimulator were delivered monoaurally through an earphone (Beyer Dynamics DT 48) with contralateral masking. The rate of stimulation was 10/sec. Recordings consisted of the average of two sets of 1250 responses, bandpass 0.2 to 2 KHz, made with a Schwarzer neuroaverager, model Basis 8000; analysis time was 10 msec and stimulus intensity 60 dB SL above the individual threshold of hearing. Based on peak latencies (PL) I-VI of BAEPs, the following parameters were calculated:
-interpeak latencies (IPL): IPL I-III = PL III - PL I IPL III-V = PL V - PL III IPL I-V = PL V - PL I -intraindividual side differences of all peaks (in this paper called "D") D X = 1/2peak X (left side) - peak X (right side)1/2 RESULTS
Statistical analysis of BAEP's in control persons revealed a normal distribution of all PL's and IPL's. As PL's of migraine patients were not normally distributed, statistical comparison was performed using the non-parametric Kolomogorov-Smirnov test for two samples. Table 1 summarizes mean, median, range and standard deviation of absolute BAEP latencies (PL) in controls (11-30) as compared to mean median and range of BAEP's in migraine patients (n = 38). (In migraine patients no standard deviation are given, as the values were not normally distributed.) Statistical analysis did not show any significant differences between both groups. Based on the mean of peak latencies of control persons (PLc) peak latencies of headache patients were considered to be pathologically delayed if exceeding the range of PLc + 2.5 S.D. Pathological BAEP's were obtained in 6 patients with migraine (common migraine: 2; classic migraine: 4, 2 of whom had basilar migraine). Table 2 shows mean, median and range of inter-peak latencies (IPL I-III, Ill-V, I-V) of migraine patients as compared to those of control persons. Based on the IPL's of control persons (IPLc) the IPL's of migraine patients did not exceed the range of IPLc + 2.5 S.D. in any case.
PEAK LATENCIES (msec) I left ear I right ear II left ear II right ear III left ear III right ear IV left ear IV right ear V left ear V right ear VI left ear VI right ear 1)
N1 37 38 37 37 38 38 33 36 38 38 37 37
Mean 1.57 1.57 2.67 2.68 3.72 3.68 4.82 4.80 5.52 5.51 7.01 7.00
Median 1.53 1.52 2.68 2.64 3.67 3.64 4.82 4.82 5.49 5.55 7.14 7.09
Range 1.19 - 2.08 1.33- 2.07 2.17 - 3.48 2.24-3.24 3.34-4.42 3.36-4.21 4.26-5.32 4.26 - 5.35 4.82-6.20 4.98-6.28 6.36-7.85 6.46-7.65
N1 50 50 48 49 50 50 45 43 49 49 45 45
Mean ± S.D. 1.50 ± 0.13 1.52 ± 0.13 2.62 ± 0.17 2.64 ± 0.18 3.69 ± 0.14 3.70 ± 0.14 4.78 ± 0.28 4.81 ± 0.29 5.50 ± 0.29 5.53 ± 0.28 7.14 ± 0.31 7.20 ± 0.29
Median Range 1.51 1.24-1.76 1.53 1.30 - 1.83 2.64 2.14 - 2.88 2.64 2.20-3.07 3.70 3.41-4.01 3.68 3.41-4.00 4.83 4.12-5.59 4.83 4.26 - 5.60 5.48 5.12-6.70 5.48 5.12-6.59 7.10 6.55-7.79 7.15 6.51-7.83
Statistical Analysis Controls/Migraineurs N.S.* N.S.* N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.
The numbers represent the number of patients, whose recordings gave distinct and reproducible results; only these patients are included in the statistical analysis.
*N.S.
= not significant
PEAK LATENCIES (msec) I III left ear I III right ear III V left ear III V right ear I V left ear I V right ear 1)
Table 1 Absolute Values of Peak Latencies (PL) I-VI of BAEPs in Patients with Various Forms of Migraine as Compared to Healthy Controls (n = 50) MIGRAINE BETWEEN ATTACKS CONTROL PERSONS
Table 2 Interpeak Latencies (IPL) I-III, III-V and I-V of BAEPs in Patients with Various Forms of Migraine (n = 38) in Comparison to Healthy Persons (n = 50). MIGRAINE BETWEEN ATTACKS CONTROL PERSONS Statistical N1 37 38 37 38 36 38
Mean 2.16 2.11 1.80 1.83 3.93 3.94
Median 2.16 2.14 1.83 1.83 3.93 3.98
Range 1.84 - 2.46 1.78- 2.52 1.23.2.35 1.43-2.17 3.17-4.42 3.41 - 4.44
N1 50 50 49 49 49 49
Mean ± S.D. 2.18 ± 0.18 2.17 ± 0.17 1.82 ± 0.24 1.83 ± 0.27 4.00 ± 0.32 4.01 ± 0.29
Median Range 2.13 1.83-2.59 2.15 1.81 - 2.70 1.84 1.39 - 3.12 1.80 1.31-3.07 4.05 3.51-5.24 3.96 3.58 - 5.07
Analysis Controls/Migraineurs N.S.* N.S.* N.S. N.S. N.S. N.S.
The numbers represent the number of patients, whose recordings gave distinct and reproducible results; only these patients are included in the statistical analysis.
*N.S.
= not significant
Statistical comparison reveals no significant difference of any interpeak latency between migrainous patients and controls. In Table 3 mean, median and range of side differences of all BAEP peak latencies (D I-VI) are given as compared to those of the control persons. Mean side differences of all BAEP peak latencies (except peak IV and VI) were significantly increased in migraine patients as compared to those of the control group. DISCUSSION
Migraine attacks are frequently associated with phonophobia and vertigo. Bickerstaff18,19 was the first to introduce "basilar artery migraine" as a migraine subtype, which involves the basilar artery territory. This syndrome is characterized by a throbbing occipital headache initiated by various prodromal brain-stem symptoms including vertigo, ataxia, visual loss, bilateral sensory alterations as well as impairment of consciousness. The existence of another syndrome has been described, characterized by attacks of vertigo associated with nystagmus, ataxia and transient disturbances of vestibular function, but without impairment of consciousness. This symptom complex ("benign recurrent vertigo") may represent a migraine variant?20-23 In general, these disturbances are considered to be of transient nature, reflecting a functional vasomotor disturbance in the areas of supply of basilar artery and posterior cerebral arteries. Some authors, however, have suggested permanent alterations of brainstem functions in patients suffering from migraine.24,25 Only a few reports are given in the literature concerning the recording of BAEP's in migraine patients. The investigation of BAEP's during migraine attacks12,13 as well as in pain-free intervals12,14-16 yield contradictory findings. The results observed in the present study are in agreement with those of the majority of other authors,12,14,15 who also did not find any statistically significant alteration of either BAEP latencies or interpeak latencies in symptom-free migraine patients as compared to healthy controls. Considering the few pathological BAEP results obtained in the present investigation, it appears that patients with basilar migraine more frequently show alterations of BAEP's than patients with other types of migraine; a pathological delay of BAEP latencies was observed in two of four investigated patients with the basilar subtype. The present study, however, revealed a significant increase of side differences of peak latencies I, II, III, V in migraine patients in comparison to control persons. Similar results have been reported by Bussone et al.16 who found inter-ear asymmetries of IPL I-V to be more pronounced in patients with migraine (during and between attacks), compared to healthy controls as well as patients with tension headache. The observed side asymmetries may indicate a slight but permanent imbalance of brainstem functions in migraine. This may possibly be due to an alteration of perfusion in the vertebrobasilar system. It also has been demonstrated that evoked potentials are influenced by cerebral metabolism, i.e. catecholaminergic and serotoninergic pathways.26,27 Together with the reported alterations of visual evoked potentials, somatosensory evoked potentials and contingent negative variation in the pain-free interval of migraine, the present findings therefore may be interpreted as a reflection of slight but permanent alterations of neuronal activities in migraine. REFERENCES
1.
Diener HC, Ndosi NK, Koletzki E, Langohr D: Visual evoked potentials in migraine, in Pfaffenrath V, Lundberg PO, Sjaastad O (eds): Updating in Headache. Berlin-Heidelberg-New York, Springer-Verlag, 1985, pp 101-106.
2.
Gawel M, Connolly JF, Clifford Rose F: Migraine patients exhibit abnormalities in the visual evoked potential. Headache 23:49-52, 1983.
3.
Kennard C, Gawel M, Rudolph N de M, Cliffford Rose F: Visual evoked potentials in migraine subjects. Res Clin Stud Headache 6:73-80, 1978.
SIDE DIFFERENCES OF PEAK LATENCIES (sec-6) DI D II D III D IV DV D VI 1)
Table 3 Side Differences (D) of BAEP Peak Latencies I-VI in Patients with Various Forms of Migraine (n = 38) as Compared to Those of Control Persons (n = 50) MIGRAINE BETWEEN ATTACKS CONTROL PERSONS
N1 37 37 38 31 37 37
Mean 9.1 11.2 10.1 10.3 12.1 16.5
Median 5 6 6.5 8 9 11
Range 0-53 0-54 0-47 0-41 0-78 0-93
N1 50 50 50 41 49 44
Mean ± S.D. 4.9 6.7 6.4 13.3 6.5 11.5
Median 3 3 5.5 11 4 3.5
Range 0-20 0-46 0-29 0-42 0-30 0-60
Statistical
Analysis Controls/Migraineurs p < 0.025 p < 0.01 p < 0.05 N.S.* p < 0.025 N.S.
The numbers represent the number of patients, whose recordings gave distinct and reproducible results; only these patients are included in the statistical analysis.
*N.S.
= not significant
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