Brainstem auditory evoked potentials (BAEPs) in childhood migraine

Brainstem auditory-evoked potential habituation and intensity-dependence related to serotonin metabolism in migraine: a longitudinal study

OBJECTIVE

Reduced habituation and increased intensity-dependence of cortical auditory-evoked potentials have been reported in migraine, but it is not known if brainstem mechanisms are chiefly or partly responsible for this hypersensitivity, if brainstem excitability or habituation changes across the migraine cycle, or how excitability relates to symptoms and serotonin metabolism.

METHODS

Brainstem auditory-evoked potentials (BAEPs) to 40, 55, and 70dB binaural rarefaction clicks were recorded in four blocks of 750 stimuli in a blinded longitudinal study in 41 migraine patients. Serotonin was measured in a blood sample from the cubital vein. The test day was classified as baseline, attack, pre-attack or post-attack.

RESULTS

Pre-attack BAEP changes were not found. Wave I, V and interpeak III-V latency increased after the attack. III-V latency correlated with headache history duration and usual headache attack duration. Habituation in wave IV-V dispersion to 40dB was found in controls but not in migraine (p=0.04). Serotonin correlated with BAEP amplitude in controls. Low serotonin correlated with more autonomic symptoms. BAEP intensity-dependence was normal in migraine.

CONCLUSIONS

BAEP latencies, but not amplitude, increase temporarily after a migraine attack. Abnormal habituation of brainstem wave IV-V dispersion in migraine may suggest increased excitation in colliculus inferior at low sound intensities, but no relation to the migraine cycle was found for wave IV-V amplitude, dispersion or habituation. The correlation between BAEP amplitude and serotonin was deranged in migraine patients, but reappeared temporarily within 72h after an attack.

SIGNIFICANCE

No evidence for pre-attack brainstem auditory sensitization was found in migraine. Intensity-dependence of AEP in migraine is probably not a passive reflection of brainstem dysfunction. BAEP changes seem to reflect a slight impact of migraine on serotonergic brainstem pathways.

Electrophysiological studies in migraine: a comprehensive review of their interest and limitations

Electrophysiological methods may help to unravel some of the pathophysiological mechanisms of migraine. Lack of habituation is the principal and most reproducible interictal abnormality in sensory processing in migraineurs. It is found in evoked potential (EP) studies for every stimulation modality including nociceptive stimuli, and it is likely to be responsible for the increased intensity dependence of EP. We have hypothesized that deficient EP habituation in migraine could be due to a reduced preactivation level of sensory cortices because of hypofunctioning subcortico-cortical aminergic pathways. This is not in keeping with simple hyperexcitability of the cortex, which has been suggested by some, but not all, studies of transcranial magnetic stimulation (TMS). A recent study of the effects of repetitive TMS on visual EP strongly supports the hypothesis that migraine is characterized by interictal cortical hypoexcitability. With regard to pain mechanisms in migraine, electrophysiological studies of trigeminal pathways using nociceptive blink and corneal reflexes have confirmed that sensitization of central trigeminal nociceptors occurs during migraine attacks.

Evoked potentials and transcranial magnetic stimulation in migraine: published data and viewpoint on their pathophysiologic significance

Migraine is a disorder in which central nervous sytem dysfunction might play a pivotal role. Electroneurophysiology seems thus particularly suited to study its pathophysiology. We have extensively reviewed evoked potential and transcranial magnetic stimulation studies performed in migraineurs in order to identify their pathophysiologic significance. Publications available to us were completed by a Medline search. Retrieved and personal data were compared with respect to methodology and interpreted according to present knowledge on cortical information processing. Results are in part contradictory which appears to be method-, patient- and disease- related. Nonetheless, both evoked potential and transcranial magnetic stimulation studies demonstrate that the cerebral cortex, and possibly subcortical structures, are dysfunctioning interictally in both migraine with and without aura. These electrophysiologic abnormalities tend to normalise just before and during an attack and some of them seem to have a clear familial and predisposing character. Besides the studies of magnetophosphenes which have yielded contrasting results, chiefly because the method is not sufficiently reliable, most recent electrophysiologic investigations of cortical activities in migraine favour deficient habituation and decreased preactivation cortical excitability as the predominant interictal dysfunctions. We propose that the former is a consequence of the latter and that it could favour both interictal cognitive disturbances as well as a cerebral metabolic disequilibrium that may play a role in migraine pathogenesis. To summarize, electrophysiologic studies demonstrate in migraine between attacks a cortical, and possibly subcortical, dysfunction of which the hallmark is deficient habituation.

Psychosocial factors in children and adolescents with migraine and tension-type headache: a controlled study and review of the literature

We investigated 341 children and adolescents to evaluate the relevance of psychosocial factors in idiopathic headache. According to the criteria of the International Headache Society, 151 subjects had migraine and 94 had tension-type headache (TTH). Ninety-six subjects were headache-free controls. Psychosocial factors covered family and housing conditions, school problems, relations in the peer group, and several other items. We found that migraine patients did not differ from headache-free controls. Patients with TTH more often had divorced parents than the headache-free controls, and they had fewer peer relations than migraineurs and controls. In addition, migraine patients were significantly more often absent from school due to headache. All other psychosocial factors failed to discriminate between the three study groups. In conclusion, this controlled study in children and adolescents suggests that migraine is not related to family and housing conditions, school situation, or peer relations, whereas TTH is associated with a higher rate of divorced parents and fewer peer relations.

The evaluation of headaches in children and adolescents

The importance of a thorough evaluation of each patient with headache is stressed. Details of the data base, pertinent information regarding the physical examination, and thoughts concerning selection of laboratory tests are provided. The majority of headache types seen in pediatric practice can correctly be identified using these methodologies.

Human brain measures of clinical pain: a review. I. Topographic mappings

A comprehensive paper (Parts I and II) has been developed to review the cerebral measures employed in studying the brain neurophysiological activities of clinical pain. Part I focuses on the electro-, magnetic-physiological assessment of clinical pain, and Part II concerns the anatomico-, chemical-physiological assessment of clinical pain. In Part I, these measures include the qualitative inspection of the conventional electroencephalogram, quantitative assessment of brain electrical spectral activity through cortical power spectrum density and coherence analyses, and quantitative averaging of cortical electrical or magnetic activities using brain evoked potentials. The mapping and measurement of these electrical activities and magnetic fields are results of recent advent in computer technology and advanced algorithms. Promises and limitations of these topographic measures in understanding pain in the brain are stated. The next article (Part II) of this paper will review tomographic imaging of pain-related brain activities in regional cerebral flow, the scanning of gross and fine brain structures by computerized axial tomography or magnetic resonance imaging, and the imaging and measurement of brain metabolic changes, energy uptake, and receptor bindings through positron emission tomography or single-photon emission computerized tomography. Molecular chemical transformation by the nuclear magnetic resonance analysis of tissue changes and analgesic-receptor interactions will also be noted.

The blink reflex in migraine

The blink reflex is an objective and useful method to study the trigeminal system. It was recorded in 43 migraine patients and the findings compared with those of 31 healthy controls. The latencies of the R1 component were in the normal range in both groups. The R2 latencies ranged between 30 and 32 ms in the control group. In contrast, more than half of the patients with migraine had R2 latencies between 32 and 35 ms in the migraine group. Some migraine patients had latencies above 35 ms. The R2 latency was statistically significantly different between controls and migraineurs (p < 0.0001). Our findings indicate that trigeminal afferents and/or polysynaptic pathway in brainstem may be altered in migraine.

Brainstem auditory evoked potentials in migraine after Rausedyl provocation

Brainstem auditory evoked potentials were recorded in 34 migraine patients (21 F and 13 M, mean age 37.4 +/- 8.1 years) after Rausedyl (2.5 mg reserpine) provocation. Intramuscular injection of reserpine induces a typical headache in migrainous controls. The findings were compared with those of 40 healthy controls (25 F and 15 M with a mean age of 40 +/- 8.9 years). We evaluated I, III, V and I-III, III-V, I-V peak and interpeak latencies. We did not find significant differences after provocation in the control group. In the migraine group, V waves were delayed significantly and consecutively I-V interpeak latencies were increased. Our results indicate an impairment of the rostral brainstem function after reserpine provocation in migraine patients.

Benefits and risks of anemia correction with recombinant human erythropoietin in children maintained by hemodialysis

Ten children with renal failure (age range 2 years 6 months to 18 years 9 months; median 11 years 10 months), maintained by long-term hemodialysis, had successful correction of their anemia after intravenous administration of recombinant human erythropoietin in a dosage escalating every 2 weeks (75 to 150 to 300 to 450 IU/kg/wk). Mean hemoglobin concentration increased from 6.4 +/- 0.9 to 11.5 +/- 1.0 gm/dl. Blood cell counts used to evaluate the correction of anemia were done after dialysis; this was especially important for children less compliant with water restriction. The higher hemoglobin concentration resulted in improvement of the quality of life, a greater tolerance for physical effort (exercise tolerance doubled and the ventilatory anaerobic threshold increased significantly), correction of some subclinical central nervous system abnormalities detected by evoked potentials testing, and reduction of bleeding time. Few side effects were noted; severe hypertension developed in one patient when postdialysis hematocrit was only 28%, and there were two episodes of hypertransaminasemia with no other evidence of liver dysfunction. We conclude that in children with renal failure the use of recombinant human erythropoietin to correct anemia is safe and strongly advisable, because of the resolution of many of the symptoms correlated with anemia.