Marit Stjern

Sleep quality, arousal and pain thresholds in migraineurs: a blinded controlled polysomnographic study

BackgroundOur aim was to compare subjective and objective sleep quality and arousal in migraine and to evaluate the relationship between sleep quality and pain thresholds (PT) in controls, interictal, preictal and postictal migraine.MethodsPolysomnography and PT (to pressure, heat and cold) measurements were done in 34 healthy controls and 50 migraineurs. Subjective sleep quality was assessed by sleep diaries, Epworth sleepiness scale, Karolinska sleep questionnaire and Pittsburgh sleep quality index. Migraineurs who had their sleep registration more than 48 h from an attack were classified as interictal while those who were less than 48 h from an attack were classified as either preictal or postictal.ResultsMigraineurs reported more insomnia and other sleep-related symptoms than controls, but the objective sleep differences were smaller and we found no differences in daytime sleepiness. Interictal migraineurs had more awakenings (p=0.048), a strong tendency for more slow-wave sleep (p=0.050), lower thermal pain thresholds (TPT) (heat pain thresholds p=0.043 and cold pain thresholds p=0.031) than controls. Migraineurs in the preictal phase had shorter latency to sleep onset than controls (p=0.003). Slow-wave sleep correlated negatively with pressure PT and slow bursts correlated negatively with TPT.ConclusionLower PT in interictal migraineurs seems related to increased sleep pressure. We hypothesize that migraineurs on the average suffer from a relative sleep deprivation and need more sleep than healthy controls. Lack of adequate rest might be an attack-precipitating- and hyperalgesia-inducing factor.

Interictal quantitative EEG in migraine: a blinded controlled study

Abnormal electroencephalography (EEG) in migraineurs has been reported in several studies. However, few have evaluated EEG findings in migraineurs during a time period when neither the last attack nor the next attack may interact with the results. We, therefore, compared interictal EEG in migraineurs and headache-free subjects with a design controlled for interference by pre-ictal changes. Pre-ictal EEG findings in the painful cranial side during the next attack after registration were also investigated. Correlations between clinical variables and EEG are reported as well. Interictal EEGs from 33 migraineurs (6 with and 27 without aura) and 31 controls were compared. Absolute power, asymmetry and relative power were studied for delta, theta and alpha frequency bands in parieto-occipital, temporal and fronto-central areas. EEG variables were correlated to attack frequency, headache duration, attack duration, pain intensity, photo- and phonophobia. Compared with controls, migraineurs had increased relative theta power in all cortical regions and increased delta activity in the painful fronto-central region. Absolute power and asymmetry were similar among groups. In age-adjusted analyses, headache intensity correlated with increased delta activity. In this blinded controlled study, we found globally increased relative theta activity in migraineurs. A slight interictal brain dysfunction is probably present between attacks.

The effect of sleep restriction on laser evoked potentials, thermal sensory and pain thresholds and suprathreshold pain in healthy subjects

OBJECTIVE Sleep restriction seems to change our experience of pain and reduce laser evoked potential (LEP) amplitudes. However, although LEP-habituation abnormalities have been described in painful conditions with comorbid sleep impairment, no study has previously measured the effect of sleep restriction on LEP-habituation, pain thresholds, and suprathreshold pain. METHOD Sixteen males and seventeen females (aged 18-31years) were randomly assigned to either two nights of delayed bedtime and four hours sleep (partial sleep deprivation) or nine hours sleep. The study subjects slept at home, and the sleep was measured with actigraphy both nights and polysomnography the last night. LEP, thermal thresholds and suprathreshold pain ratings were obtained the day before and the day after intervention. The investigator was blinded. ANOVA was used to evaluate the interaction between sleep restriction and day for each pain-related variable. RESULTS LEP-amplitude decreased after sleep restriction (interaction p=0.02) compared to subjects randomized to nine hours sleep. LEP-habituation was similar in both groups. Thenar cold pain threshold decreased after sleep restriction (interaction p=0.009). Supra-threshold heat pain rating increased temporarily 10s after stimulus onset after sleep restriction (interaction p=0.01), while it did not change after nine hours sleep. CONCLUSION Sleep restriction reduced the CNS response to pain, while some of the subjective pain measures indicated hyperalgesia. SIGNIFICANCE Since LEP-amplitude is known to reflect both CNS-pain-specific processing and cognitive attentive processing, our results suggest that hyperalgesia after sleep restriction might partly be caused by a reduction in cortical cognitive or perceptual mechanisms, rather than sensory amplification.

The occipital alpha rhythm related to the ''migraine cycle" and headache burden: A blinded, controlled longitudinal study

OBJECTIVE Neurophysiological studies have shown a fluctuating neural dysfunction in migraine. This pathophysiological feature has not previously been investigated by quantitative electroencephalography (QEEG). The alpha rhythm is especially interesting, because it is influenced by ischemia and neuronal dysfunction within the posterior circulation area. METHODS We investigated alpha peak frequency, variability, peak power and asymmetry in 41 migraineurs and 32 controls. Electroencephalography (EEG) was recorded on three random days and retrospectively classified as preattack, attack, postattack or interictal, based on the patients headache diaries. We also searched for correlations between alpha rhythm parameters and disease duration, attack duration, attack frequency, pain intensity and photophobia. RESULTS Peak frequency reduction correlated with increasing disease- and attack duration. Frequency variability increased before the attack, while peak power increased during the attack. Alpha peak width, peak frequency and peak power were similar for migraineurs and controls in the interictal period. CONCLUSION The accumulated burden of migraine caused slight alterations in the physiology of the visual cortex. Small alpha rhythm changes were observed along the migraine cycle. SIGNIFICANCE This is a longitudinal, controlled study. It is the first to report changes in alpha rhythm with increased migraine load, even when the QEEG is not influenced by recent or imminent attacks.

Sleep quality, arousal and pain thresholds in tension-type headache: A blinded controlled polysomnographic study

Introduction We aimed to compare subjective and objective sleep quality in tension-type headache (TTH) patients and to evaluate the relationship between sleep quality and pain thresholds (PT) in controls and TTH patients. Methods A blinded cross-sectional study where polysomnography (PSG) and PT (to pressure, heat and cold) measurements were done in 20 patients with TTH (eight episodic (ETTH) and twelve chronic (CTTH) TTH) and 29 healthy controls. Sleep diaries and questionnaires were applied. Results TTH patients had more anxiety (p = 0.001), insomnia (p < 0.0005), daytime tiredness (p < 0.0005) and reduced subjective sleep quality (p < 0.0005) compared to healthy controls. Sleep diaries revealed more long awakenings in TTH (p = 0.01) but no total sleep-time differences. TTH patients had more slow-wave sleep (p = 0.002) and less fast arousals (p = 0.004) in their PSGs. CTTH subjects had lower pressure PT (p = 0.048) and more daytime sleepiness than the controls (p = 0.039). Among TTH lower cold PT (CPT) correlated inversely with light sleep (N1) (r = −0.49, p = 0.003) while slow arousals correlated inversely with headache-frequency (r = −0.64, p = 0.003). Conclusions We hypothesize that TTH patients need more sleep than healthy controls and might be relatively sleep deprived. Inadequate sleep may also contribute to increased pain sensitivity and headache frequency in TTH.

Impaired Awareness of Hypoglycemia in Adults With Type 1 Diabetes Is Not Associated With Autonomic Dysfunction or Peripheral Neuropathy

OBJECTIVE Impaired awareness of hypoglycemia (IAH) is a risk factor for severe hypoglycemia in people with insulin-treated diabetes; autonomic neuropathy has been suggested to underlie its development. The aim was to evaluate a putative association between IAH and autonomic dysfunction using novel and sensitive measures of autonomic neural function. RESEARCH DESIGN AND METHODS Sixty-six adults with type 1 diabetes were studied, 33 with IAH and 33 with normal awareness of hypoglycemia (NAH), confirmed by formal testing. Participants were matched for age, sex, and diabetes duration. Clinical and laboratory evaluations included extensive autonomic function testing, peripheral nerve conduction studies, and quantitative sensory testing. Composite abnormality Z scores were used for group comparisons. RESULTS The IAH and NAH group had similar median (interquartile range) age of 48 (14.5) vs. 47 (14.5) years, diabetes duration of 30 (13.5) vs. 31 (13.5) years, and mean ± SD HbA1c 7.8 ± 2.2% vs. 8.1 ± 1.9%, respectively. The autonomic composite Z score did not differ between the two groups (mean difference −0.15, 95% CI −0.46, 0.16; P = 0.33), nor did the thermal detection (mean difference 0.15, 95% CI −0.31, 0.61; P = 0.51) or nerve conduction scores (mean difference 0.03, 95% CI −0.43, 0.49; P = 0.89). CONCLUSIONS In adults with type 1 diabetes, IAH was not associated with autonomic dysfunction or peripheral neuropathy.

Habituation of laser-evoked potentials by migraine phase: a blinded longitudinal study

BackgroundMigraineurs seem to have cyclic variations in cortical excitability in several neurophysiological modalities. Laser-evoked potentials (LEP) are of particular interest in migraine because LEP specifically targets pain pathways, and studies have reported different LEP-changes both between and during headaches. Our primary aim was to explore potential cyclic variations in LEP amplitude and habituation in more detail with a blinded longitudinal study design.MethodsWe compared N1 and N2P2 amplitudes and habituation between two blocks of laser stimulations to the dorsal hand, obtained from 49 migraineurs with four sessions each. We used migraine diaries to categorize sessions as interictal (> one day from previous and to next attack), preictal (< one day before the attack), ictal or postictal (< one day after the attack). Also, we compared 29 interictal recordings from the first session to 30 controls.ResultsN1 and N2P2 amplitudes and habituation did not differ between preictal, interictal and postictal phase sessions, except for a post hoc contrast that showed deficient ictal habituation of N1. Habituation is present and similar in migraineurs in the interictal phase and controls.ConclusionsHand-evoked LEP amplitudes and habituation were mainly invariable between migraine phases, but this matter needs further study. Because hand-evoked LEP-habituation was similar in migraineurs and controls, the present findings contradict several previous LEP studies. Pain-evoked cerebral responses are normal and show normal habituation in migraine.

Alterations in post-movement beta event related synchronization throughout the migraine cycle: A controlled, longitudinal study

Background The migraine brain is believed to have altered cortical excitability compared to controls and between migraine cycle phases. Our aim was to evaluate post-activation excitability through post-movement beta event related synchronization (PMBS) in sensorimotor cortices with and without sensory discrimination. Subjects and methods We recorded EEG of 41 migraine patients and 31 healthy controls on three different days with classification of days in relation to migraine phases. During each recording, subjects performed one motor and one sensorimotor task with the right wrist. Controls and migraine patients in the interictal phase were compared with repeated measures (R-) ANOVA and two sample Student’s t-test. Migraine phases were compared to the interictal phase with R-ANOVA and paired Student’s t-test. Results The difference between PMBS at the contralateral and ipsilateral sensorimotor cortex was altered throughout the migraine cycle. Compared to the interictal phase, we found decreased PMBS at the ipsilateral sensorimotor cortex in the ictal phase and increased PMBS in the preictal phase. Lower ictal PMBS was found in bilateral sensorimotor cortices in patients with right side headache predominance. Conclusion The cyclic changes of PMBS in migraine patients may indicate that a dysfunction in deactivation and interhemispheric inhibition of the sensorimotor cortex is involved in the migraine attack cascade.

P04.4 The α-rhythm in migraine: A longitudinal EEG study

Introduction: Increased variability (instability) of posterior a-rhythm accompanied the preictal phase in one study of migraineurs with aura. This observation has never been confirmed, and migraineurs without aura have not been investigated. It is also unknown how the temporal relationship to the migraine attack influences the electroencephalogram (EEG). Aim: to measure a-rhythm frequency, a-rhythm variability and power at different times during the ‘‘migraine cycle’’. Methods: EEG was recorded at three different days from 40 migraineurs and 33 age and sex matched controls. A fast Fourier transform (FFT) was applied to occipital and parietal EEG, and the spectral a-band frequency, variability and power was calculated. The headache diary of the migraineurs enabled us to classify recordings as interictal, preictal, ictal and postictal. Results: a-frequency variability was more asymmetric in migraineurs with aura compared with controls, but most a parameters were not different between groups. The symptomatic hemisphere had increased variability and slower peak frequency in this group as well. The subdivision of the interictal period in preictal, postictal and silent period, revealed a few group differences not discovered when analysing data from the whole interictal period. Lower a start frequency in the symptomatic hemisphere before attack and in the asymptomatic side after attack was found in migraineurs with aura compared with patients without aura. We found a slowing of the alpha frequency with increasing age in the migraine group that was not present among controls. Slowing was also found with duration of attack and photophobia. Conclusion: Our results that a-rhythm is generally normal in migraine; however, in a few EEG variables we observed changes which might suggest the presence of a fluctuating occipital instability in migraine. Postictal apeak depression was the most consistent EEG change.