Photic EEG-driving responses related to ictal phases and trigger sensitivity in migraine: a longitudinal, controlled study

INTRODUCTION

Photic driving is believed to be increased in migraineurs and has been interpreted as a sign of cortical hyperexcitability. However, most previous studies have included patients in various phases of the migraine cycle. The results are, therefore, difficult to interpret as neurophysiological abnormalities tend to accumulate close to the attack in migraineurs.

SUBJECTS AND METHODS

We recorded steady state visual evoked EEG-responses (SSVEPs) for 6, 12, 18 and 24 Hz flash stimuli from 33 migraineurs without aura, eight migraineurs with aura and 32 healthy controls. Interictal recordings were compared pair-wise with recordings before, during and after attack, as well as with EEGs from healthy controls. Driving power was also correlated with sensory hypersensitivity and severity of migraine.

RESULTS

Between attacks, driving responses to 18 Hz and 24 Hz were attenuated in migraineurs without aura. Driving power of 12 Hz increased before the attack. Attack trigger sensitivity, photophobia, pain intensity and a family history of migraine were related to decreased and/or symmetric photic driving.

CONCLUSIONS

Earlier results may have overestimated the driving response in migraine due to inclusion of recordings during the preictal interval and/or habituation among controls. Abnormal photic driving may be related to the pathophysiology of clinical sensory hypersensitivity.

What initiates a migraine attack? Conclusions from four longitudinal studies of quantitative EEG and steady-state visual-evoked potentials in migraineurs

OBJECTIVES

Quantitative electroencephalograpic (QEEG) frequency spectra and steady-state visual-evoked potentials (SSVEP) are indicators of corticothalamic excitability (e.g., arousal). Increased interictal excitability is suggested to be an important element in the migraine pathophysiology. In this paper, we summarize our results from four studies of QEEG and SSVEP recordings in migraineurs interictally and in the days before an attack with the intention to shed light on attack-initiating mechanisms.

MATERIAL AND METHODS

Thirty-two healthy controls, 33 migraineurs without and eight with aura each had three EEGs with photic stimulation on different days. Using the patient headache diaries, we classified the recordings as interictal, preictal, ictal, or post-ictal retrospectively. Interictal recordings were compared pairwise with attack-related EEGs from the same patient as well as with control EEGs. We also correlated clinical variables with the QEEG and SSVEP data.

RESULTS

Between attacks, we found increased relative theta activity and attenuated medium-frequency photic responses in migraineurs without aura compared with those in controls. Within 36 h before the attack, slow and asymmetric EEG activity developed. Increased trigger sensitivity and photophobia correlated with higher theta power and depressed photic responses. Attack duration, migraine history duration, and pain intensity were associated with EEG slowing.

CONCLUSIONS

A general tendency toward EEG slowing and depression of photic responses characterized the migraine group. This pattern was also related to increased severity of symptoms. A change in cortical activity occurred within 36 h before attacks. Our results indicate that thalamocortical hypoexcitability is associated with attack initiation and sensory hypersensitivity in migraine.

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.

Age prediction in sub-adults based on MRI segmentation of 3rd molar tissue volumes

PURPOSE

Our aim was to investigate tissue volumes measured by MRI segmentation of the entire 3rd molar for prediction of a sub-adult being older than 18 years.

MATERIAL AND METHOD

We used a 1.5-T MR scanner with a customized high-resolution single T2 sequence acquisition with 0.37 mm iso-voxels. Two dental cotton rolls drawn with water stabilized the bite and delineated teeth from oral air. Segmentation of the different tooth tissue volumes was performed using SliceOmatic (Tomovision^©). Linear regression was used to analyze the association between mathematical transformation outcomes of the tissue volumes, age, and sex. Performance of different transformation outcomes and tooth combinations were assessed based on the p value of the age variable, combined or separated for each sex depending on the selected model. The predictive probability of being older than 18 years was obtained by a Bayesian approach.

RESULTS

We included 67 volunteers (F/M: 45/22), range 14-24 years, median age 18 years. The transformation outcome (pulp + predentine)/total volume for upper 3rd molars had the strongest association with age (p = 3.4 × 10^-9).

CONCLUSION

MRI segmentation of tooth tissue volumes might prove useful in the prediction of age older than 18 years in sub-adults.

Prediction of Age Older than 18 Years in Sub-adults by MRI Segmentation of 1st and 2nd Molars

PURPOSE

To investigate prediction of age older than 18 years in sub-adults using tooth tissue volumes from MRI segmentation of the entire 1st and 2nd molars, and to establish a model for combining information from two different molars.

MATERIALS AND METHODS

We acquired T2 weighted MRIs of 99 volunteers with a 1.5-T scanner. Segmentation was performed using SliceOmatic (Tomovision©). Linear regression was used to analyse the association between mathematical transformation outcomes of tissue volumes, age, and sex. Performance of different outcomes and tooth combinations were assessed based on the p-value of the age variable, common, or separate for each sex, depending on the selected model. The predictive probability of being older than 18 years was obtained by a Bayesian approach using information from the 1st and 2nd molars both separately and combined.

RESULTS

1st molars from 87 participants, and 2nd molars from 93 participants were included. The age range was 14-24 years with a median age of 18 years. The transformation outcome (high signal soft tissue + low signal soft tissue)/total had the strongest statistical association with age for the lower right 1st (p= 7.1*10-4 for males) and 2nd molar (p=9.44×10-7 for males and p=7.4×10-10 for females). Combining the lower right 1st and 2nd molar in males did not increase the prediction performance compared to using the best tooth alone.

CONCLUSION

MRI segmentation of the lower right 1st and 2nd molar might prove useful in the prediction of age older than 18 years in sub-adults. We provided a statistical framework to combine the information from two molars.

X-linked hypophosphataemia

X-linked hypophosphataemia is a rare genetic disorder that causes renal phosphate wasting, impaired mineralisation of teeth and bones, skeletal deformities and limited mobility, all of which significantly impact on health and quality of life. This clinical review examines the recommendations for diagnosing, treating and monitoring adults with the condition.

CT and MR imaging used in age estimation: a systematic review

Computer Tomography (CT) and Magnetic Resonance Imaging (MRI) may be useful tools in assessment of age of an individual. This article presents a review of published studies using CT or MRI in dental age estimation. They were published between July 2004 and September 2017 investigating different types of teeth, methods and formulae for age estimation. Twenty-seven articles were included. The different studies show good results, and it seems that a combination of different types of teeth, methods (depending on the degree of root formation) and cooperation between different disciplines in the same study gives a higher accuracy.

MRI segmentation of tooth tissue in age prediction of sub-adults - a new method for combining data from the 1st, 2nd, and 3rd molars

PURPOSE

We aimed to establish a model combining MRI volume measurements from the 1st, 2nd and 3rd molars for age prediction in sub-adults and compare the age prediction performance of different combinations of all three molars, internally in the study cohort.

MATERIAL AND METHOD

We examined 99 volunteers using a 1.5 T MR scanner with a customized high-resolution single T2 sequence. Segmentation was performed using SliceOmatic (Tomovision©). Age prediction was based on the tooth tissue ratio (high signal soft tissue + low signal soft tissue)/total. The model included three correlation parameters to account for statistical dependence between the molars. Age prediction performance of different combinations of teeth for the three molars was assessed using interquartile range (IQR).

RESULTS

We included data from the 1st molars from 87 participants (F/M 59/28), 2nd molars from 93 (F/M 60/33) and 3rd molars from 67 (F/M 45/22). The age range was 14-24 years with a median age of 18 years. The model with the best age prediction performance (smallest IQR) was 46-47-18 (lower right 1st and 2nd and upper right 3rd molar) in males. The estimated correlation between the different molars was 0.620 (46 vs. 47), 0.430 (46 vs. 18), and 0.598 (47 vs. 18). IQR was the smallest in tooth combinations including a 3rd molar.

CONCLUSION

We have established a model for combining tissue volume measurements from the 1st, 2nd and 3rd molars for age prediction in sub-adults. The prediction performance was mostly driven by the 3rd molars. All combinations involving the 3rd molar performed well.