Primary headache pathophysiology in children: The contribution of clinical neurophysiology

Children and adolescents with primary headaches exhibit altered sensory profiles - a multi-modal investigation

BACKGROUND

Pediatric headache is an increasing medical problem that has adverse effects on children's quality of life, academic performance, and social functioning. Children with primary headaches exhibit enhanced sensory sensitivity compared to their healthy peers. However, comprehensive investigations including multimodal sensory sensitivity assessment are lacking. This study aimed to compare sensory sensitivity of children with primary headaches with their healthy peers across multiple sensory domains.

METHODS

The study included 172 participants aged 6 to 17 years (M = 13.09, SD = 3.02 years; 120 girls). Of these 80 participants were patients with migraine, 23 were patients with tension-type headache, and 69 were healthy controls. The following sensory measures were obtained: Mechanical Detection Threshold (MDT), Mechanical Pain Threshold (MPT), Mechanical Pain Sensitivity (MPS), detection and pain threshold for Transcutaneous Electrical Nerve Stimulation (TENS), olfactory and intranasal trigeminal detection threshold, and odor identification ability. Sensory sensitivity was compared between groups with a series of Kruskal-Wallis tests. Binomial regression models were used to compare the relative utility of sensory sensitivity measures in classifying participants into patients and healthy controls, as well as into patients with migraine and tension-type headache.

RESULTS

Patients with migraine had lower MPT measured at the forearm than patients with tension-type headaches and healthy controls. MPS was higher in patients with migraine than in healthy controls. All patients with headaches had lower detection threshold of TENS and higher olfactory sensitivity. Healthy controls showed increased intranasal trigeminal sensitivity. Scores in MPS, TENS, and olfactory and trigeminal thresholds were significantly predicting presence of primary headaches. Additionally, scores in MPT, olfactory and trigeminal threshold were positive predictors of type of headache.

CONCLUSIONS

Children with primary headaches exhibit different sensory profiles than healthy controls. The obtained results suggest presence of increased overall, multimodal sensitivity in children with primary headaches, what may negatively impact daily functioning and contribute to further pain chronification.

TRIAL REGISTRATION

The study was registered in the German Registry of Clinical Trials (DRKS) DRKS00021062.

Pediatric Migraine and Visual Cortical Excitability: A Prospective Observational Study with Sound-Induced Flash Illusions

The pathophysiological mechanisms underlying migraine are more difficult to investigate in children than in the adult population. Abnormal cortical excitability turns out to be one of the most peculiar aspects of migraine, accounting for the manifestations of migraine attacks. Recently, visual cortical excitability has been explored effectively in adult migraineurs with a technique based on cross-modal audio-visual illusions (with sound-induced flash illusions (SIFIs) being reduced in migraineurs compared to non-migraineur subjects). On such a basis, in this study, we investigated visual cortical excitability in children with migraine using SIFIs using combinations of visual and sound stimuli presented randomly. We evaluated 26 children with migraine without aura and 16 healthy children. Migraineurs did not differ from the age-matched healthy subjects regarding fission or fusion illusions but perceived more flashes in trials of multiple flashes with or without beeps. The higher number of SIFIs in migraineur children compared to adults may be due to a greater propensity of visual stimulation to be driven by auditory stimuli (i.e., acoustic dominance). The increased ability to perceive flashes reveals a hyperfunctional visual cortex, demonstrating that the use of SIFIs is a valid tool for assessing visual cortical responsiveness even in pediatric migraine.

Interictal Cognitive Performance in Children and Adolescents With Primary Headache: A Narrative Review

Primary headache is a very common and disabling disease. The burden of pain and recurrent attacks may lead to a poor quality of life, anxiety and depression. An increased risk of low functioning and curricular performances in young patients with primary headache has been described. The mechanisms underlying the relationship between migraine and poor school achievement may be various and could be a reflection of weak cognitive skills. Data concerning the cognitive functioning in the free pain interval in pediatric age are under-investigated and results are far from conclusive. The present review article suggests that, though considered a benign disease, pediatric migraine may be associated to altered neuropsychological functioning in the interictal phase. Although children and adolescents with migraine generally have a normal intelligence, they may show a not homogeneous cognitive profile, characterized by possible difficulties in verbal skills, in particular comprehension abilities. Pediatric primary headache may present altered neuropsychological functioning involving attentional resources, processing speed and memory, particularly verbal memory. Given the impact that this disease can have on school performance and the tendency to persist from childhood to adulthood, a cognitive screening in young patients affected by primary headache is pivotal. Additional neuropsychological research using more homogenous methods is needed.

GABA and glutamate in pediatric migraine

Migraine is one of the top 5 most prevalent childhood diseases; however, effective treatment strategies for pediatric migraine are limited. For example, standard adult pharmaceutical therapies are less effective in children and can carry undesirable side effects. To develop more effective treatments, improved knowledge of the biology underlying pediatric migraine is necessary. One theory is that migraine results from an imbalance in cortical excitability. Magnetic resonance spectroscopy (MRS) studies show changes in GABA and glutamate levels (the primary inhibitory and excitatory neurotransmitters in the brain, respectively) in multiple brain regions in adults with migraine; however, they have yet to be assessed in children with migraine. Using MRS and GABA-edited MRS, we show that children (7-13 years) with migraine and aura had significantly lower glutamate levels in the visual cortex compared to controls, the opposite to results seen in adults. In addition, we found significant correlations between metabolite levels and migraine characteristics; higher GABA levels were associated with higher migraine burden. We also found that higher glutamate in the thalamus and higher GABA/Glx ratios in the sensorimotor cortex were associated with duration since diagnosis, i.e., having migraines longer. Lower GABA levels in the sensorimotor cortex were associated with being closer to their next migraine attack. Together, this indicates that GABA and glutamate disturbances occur early in migraine pathophysiology and emphasizes that evidence from adults with migraine cannot be immediately translated to pediatric sufferers. This highlights the need for further mechanistic studies of migraine in children, to aid in development of more effective treatments.

Atypical Facial and Head Pain in Childhood and Adolescence

PURPOSE OF REVIEW

This review will consider forms of atypical facial and head pain in children and adolescents. A brief and general overview of typical head and facial pains and treatments will be offered. Moreover, atypical head and face pain will be discussed with treatment options.

RECENT FINDINGS

The most recent literature including case reports will be evaluated; possible pathophysiological mechanisms, resulting disabilities, and family and social impact will be discussed. General indications for pharmacological treatment will be reviewed, when needed in more disabling cases. Also, non-pharmacological treatments that are especially suitable for this category of patients will be illustrated and discussed.

Applying a Lifespan Developmental Perspective to Chronic Pain: Pediatrics to Geriatrics

An ideal taxonomy of chronic pain would be applicable to people of all ages. Developmental sciences focus on lifespan developmental approaches, and view the trajectory of processes in the life course from birth to death. In this article we provide a review of lifespan developmental models, describe normal developmental processes that affect pain processing, and identify deviations from those processes that lead to stable individual differences of clinical interest, specifically the development of chronic pain syndromes. The goals of this review were 1) to unify what are currently separate purviews of "pediatric pain," "adult pain," and "geriatric pain," and 2) to generate models so that specific elements of the chronic pain taxonomy might include important developmental considerations.

PERSPECTIVE

A lifespan developmental model is applied to the forthcoming Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks-American Pain Society Pain Taxonomy to ascertain the degree to which general "adult" descriptions apply to pediatric and geriatric populations, or if age- or development-related considerations need to be invoked.

Age- and sex-related differences in the presentation of paediatric migraine: A retrospective cohort study

Introduction Although migraine is a common headache complaint in children and adolescents there remains a significant gap in understanding the unique aspects of the disease in these age groups and their evolution with development. The aim of this retrospective cohort study was to identify migraine features that are influenced by age and sex. Methods The headache characteristics of 359 paediatric patients with a clinical diagnosis of migraine from a tertiary paediatric headache clinic were assessed. Patients retrospectively reported headache characteristics during a structured intake interview and clinical exam. Headache characteristics, description and associated symptoms were compared between children (age ≤ 12 years) and adolescents (age > 12 years), and between male and female migraineurs. Results Several migraine features differed significantly with age and/or sex, including: (i) a marked change from a 1:1 sex ratio in children to a 2:1 predominance of girls in adolescents; (ii) a higher frequency of headache attacks per month in adolescents and female migraineurs; (iii) a higher proportion of adolescents endorsed a 'throbbing' pain quality; (iv) a higher proportion of children reporting nausea and vomiting; and (v) a higher proportion of adolescents, particularly female migraineurs, had a diagnosis of a co-morbid anxiety. Conclusion The presentation of migraine, both in terms of its headache characteristics and associated symptoms, appear to vary as a function of age and sex. Given that migraine symptoms have a neural basis, it is not surprising that during the key period of neurodevelopment from childhood to adolescence this may impact their presentation.

Cortical hyper-excitability in healthy children: evidence from habituation and recovery cycle phenomena of somatosensory evoked potentials

AIM

To compare neurophysiological parameters of central nervous system excitability in healthy children/adolescents with those of healthy adults.

METHOD

Two experimental protocols were used in 19 healthy children/adolescents (10 males and 9 females, mean age 9y 11mo [SD 2y 9mo], range 5-15y) and 19 healthy adults (8 males and 11 females, mean age 36y 6mo [SD 7y 9mo], range 27-51y). First, we administered repetitive trains of innocuous electrical stimulation of the median nerve and analysed habituation (progressive attenuation) of the cervical and cortical responses. Second, we administered several blocks of two closely timed electrical innocuous stimuli of the median nerve (with interstimulus intervals set at 5, 10, and 20ms in each block) and analysed the recovery index (the percentage of the response to the second stimulus with respect to that to the first).

RESULTS

Clear-cut neurophysiological signs of cortical hyper-excitability were found in children/adolescents but not in adults. In contrast with the adults, the children/adolescents did not attenuate cortical responses to repetitive stimulation, and presented with extremely shortened recovery cycle. At baseline, both groups presented with comparable cortical responses.

INTERPRETATION

Healthy children/adolescents present cortical hyper-excitability compared with healthy adults. These findings agree with previous findings that show an overall imbalance of excitatory and inhibitory neuronal and neurochemical mechanisms in favour of excitatory ones, in the healthy developing cerebral cortex.

Diagnosis of primary headache in children younger than 6 years: A clinical challenge

Background Criteria defined by the International headache Society are commonly used for the diagnosis of the different headache types in both adults and children. However, some authors have stressed some limits of these criteria when applied to preschool age. Objective Our study aimed to describe the characteristics of primary headaches in children younger than 6 years and investigate how often the International Classification of Headache Disorders (ICHD) criteria allow a definitive diagnosis. Methods This retrospective study analysed the clinical feature of 368 children younger than 6 years with primary headache. Results We found that in our patients the percentage of undefined diagnosis was high when either the ICHD-II or the ICHD-III criteria were used. More than 70% of our children showed a duration of their attacks shorter than 1 hour. The absence of photophobia/phonophobia and nausea/vomiting significantly correlate with tension-type headache (TTH) and probable TTH. The number of first-degree relatives with migraine was positively correlated to the diagnosis of migraine in the patients ( p < 0.001). Conclusions Our study showed that the ICHD-III criteria are difficult to use in children younger than 6 years. The problem is not solved by the reduction of the lowest duration limit for the diagnosis of migraine to 1 hour, as was done in the ICHD-II.

Pattern-Reversal Visual Evoked Potential Parameters and Migraine in the Teenage Population

Although migraine represents one of the most common form of primary headache in the teenage population, most neurophysiologic studies are only on the adulthood. We investigated 38 teenage patients with migraine with aura, 17 male and 21 female, with a mean age of 16.2 years, comparing them with gender- and age-matched patients with migraine without aura and healthy subjects. Also, characteristics of aura were correlated with pattern-reversal visual evoked potential parameters. There was a significant difference in left and right eye N2 wave latencies between migraine with aura and migraine without aura patients or healthy controls. In migraine with aura and migraine without aura, 26.3% of patients had abnormal wave latency. Reported tunnel vision during the aura was correlated with lower N1P1 and/or P1N2 wave amplitudes. Also, higher amplitude in patients with migraine with aura correlated with younger age and earlier disease onset, whereas longer aura duration correlated with prolonged wave latency. Findings suggest that migraine subtypes may be differentiated on the basis of N2 wave latency prolongation.

Frequency of pediatric migraine with aura in a clinic-based sample

OBJECTIVE

To assess the prevalence and risk factors for pediatric migraine with aura (MWA) among patients presenting to pediatric neurology clinics.

BACKGROUND

Headache is a common complaint among children, and the prevalence of migraine is about 8%. Up to one third of adults with migraine report experiencing aura; however, the exact percentage in children is unknown.

METHODS

Medical records of children presenting with headache to three pediatric neurology clinics in Haifa in the last 5 years were retrospectively reviewed. Inclusion criteria were a diagnosis of migraine headache at 5-18 years of age.

RESULTS

Of 260 children (140 female) who had migraine, 26.2% experienced aura. MWA was more common among females compared to males (32.6% vs 18.9%, P < .01) and among older children (OR: 2.50, 95% CI: 1.20-5.20; P < .01). Among those who experienced aura, visual aura was more common in females than males (66.7% vs 33.3%, P < .04). Family history of migraine was strongly related to MWA (P < .02): the odds of MWA were 2.46 times greater in children who had a family history of migraine. (OR: 2.46, 95% CI: 1.08-5.62; P < .03).

CONCLUSIONS

MWA is as common in children as in adults. Aura is more common in older children. Children who have MWA are more likely to have a family history of migraine.

Laser-evoked potential habituation and central sensitization symptoms in childhood migraine

Objectives

Few studies have addressed central sensitization symptoms and pain processing in childhood migraine. Our aims were to examine pain sensitivity and responses, including habituation, evoked by CO2 laser stimuli (laser-evoked potentials (LEPs)) in a cohort of children with migraine compared to non-migraine controls and to determine the correlation between LEP features and signs of central sensitization.

Methods

Thirty-five patients 8–15 years of age with migraines without aura were evaluated during the inter-critical phase and were compared to 17 controls. LEPs were analyzed, and their main features were correlated with clinical symptoms including allodynia and pericranial tenderness.

Results

The laser-evoked pain threshold was lower and the N2P2 vertex complex amplitude was higher in children with migraines. Furthermore, habituation of vertex waves of LEPs clearly showed a tendency toward progressive amplitude enhancement in the migraine group. Acute allodynia and inter-critical pericranial tenderness correlated with trigeminal LEP features, particularly with the abnormal habituation pattern.

Discussion

Abnormalities of pain processing and symptoms of central sensitization appear to be characteristics of children with migraine. Reduced habituation and progressive amplification of cortical responses to laser stimuli indicate an overactive nociceptive system at the onset of migraine, and this hyperactivity may subtend allodynia and pericranial tenderness. Future prospective trials may aid in the early identification of clinical phenotypes that display a tendency to develop into the chronic form of migraine, warranting a timely therapeutic approach.

White matter microstructure abnormalities in pediatric migraine patients

BACKGROUND

Diffusion tensor (DT) magnetic resonance imaging (MRI) provides several quantities with the potential to disclose white matter (WM) microstructural abnormalities. We explored alterations of WM architecture in pediatric migraine patients using DT MRI and two different methods of analysis.

METHODS

Dual-echo and DT MRI scans were acquired from 15 pediatric migraine patients and 15 age-matched controls. Whole-brain voxel-wise comparisons of WM DT MRI abnormalities were performed using tract-based-spatial-statistics (TBSS). A DT probabilistic tractography analysis was also run.

RESULTS

Both TBSS and DT tractography analysis showed that, compared to controls, pediatric migraine patients had significant lower mean (MD), axial (AD) and radial (RD) diffusivity of WM tracts located in the brainstem, thalamus and fronto-temporo-occipital lobes, bilaterally. Patients also experienced increased fractional anisotropy (FA) of the optic radiations. No correlation was found between WM tract abnormalities and disease duration and attack frequency.

CONCLUSIONS

Pediatric migraine patients harbor diffuse brain WM microstructural abnormalities. High FA and low MD, AD and RD in these patients might be explained by repeated neuronal activation, which may lead to cell swelling and stimulate activity-dependent myelin-modulation, or by increased fiber and dendritic densities. Both these mechanisms might reflect a hyperexcitability of the brain in migraineurs.

Development of spatial integration depends on top-down and interhemispheric connections that can be perturbed in migraine: a DCM analysis

In humans, spatial integration develops slowly, continuing through childhood into adolescence. On the assumption that this protracted course depends on the formation of networks with slowly developing top-down connections, we compared effective connectivity in the visual cortex between 13 children (age 7-13) and 14 adults (age 21-42) using a passive perceptual task. The subjects were scanned while viewing bilateral gratings, which either obeyed Gestalt grouping rules [colinear gratings (CG)] or violated them [non-colinear gratings (NG)]. The regions of interest for dynamic causal modeling were determined from activations in functional MRI contrasts stimuli > background and CG > NG. They were symmetrically located in V1 and V3v areas of both hemispheres. We studied a common model, which contained reciprocal intrinsic and modulatory connections between these regions. An analysis of effective connectivity showed that top-down modulatory effects generated at an extrastriate level and interhemispheric modulatory effects between primary visual areas (all inhibitory) are significantly weaker in children than in adults, suggesting that the formation of feedback and interhemispheric effective connections continues into adolescence. These results are consistent with a model in which spatial integration at an extrastriate level results in top-down messages to the primary visual areas, where they are supplemented by lateral (interhemispheric) messages, making perceptual encoding more efficient and less redundant. Abnormal formation of top-down inhibitory connections can lead to the reduction of habituation observed in migraine patients.

Migraine equivalents as part of migraine syndrome in childhood

BACKGROUND

Migraine equivalents are common clinical conditions without a headache component, occurring as repeated episodes with complete remission between episodes. They include abdominal migraine, cyclical vomiting, benign paroxysmal vertigo, and benign paroxysmal torticollis. Other clinical entities, such as motion sickness and limb pain have been associated with migraine. We aimed to investigate the prevalence of migraine equivalents in a large population of children referred to a pediatric headache center and to analyze the possible relationship between migraine equivalents and headache features.

METHODS

A total of 1134 of children/adolescents (73.2% with migraine and 26.8% with tension-type headache) were included. Patients were divided into two groups according to the episode frequency (high and low). Pain intensity was rated on a three-level graduate scale (mild, moderate, and severe pain).

RESULTS

Migraine equivalents were reported in 70.3% of patients. Abdominal migraine (48.9%), limb pain (43.9%), and motion sickness (40.5%) were the most common migraine equivalents. Although headache type (migraine or tension-type headache) did not correlate with migraine equivalents presence (χ(2) = 33.2; P = 0.27), high frequency of headache episodes correlated with the occurrence of migraine equivalents. Moreover, migraine equivalents indicated a protective role for some accompanying feature of the headache episode.

CONCLUSIONS

Our results suggest that migraine equivalents should not be considered merely as headache precursors, but they as part of the migrainous syndrome. Thus, their inclusion among the diagnostic criteria for pediatric migraine/tension-type headache is useful.

Risk factors for migraine and tension-type headache in 11 year old children

BACKGROUND

Though migraine and tension type headache are both commonly diagnosed in childhood, little is known about their determinants when diagnosed prior to puberty onset. Our aim was to determine psychosocial- and health-related risk factors of migraine and tension-type headache in 11 year old children.

METHODS

871 New Zealand European children were enrolled in a longitudinal study at birth and data were collected at birth, 1, 3.5, 7, and 11 years of age. Primary headache was determined at age 11 years based on the International Headache Society. Perinatal factors assessed were small for gestational age status, sex, maternal smoking during pregnancy, maternal perceived stress, and maternal school leaving age. Childhood factors assessed were sleep duration, percent body fat, television watching, parent and self-reported total problem behaviour, being bullied, and depression.

RESULTS

Prevalence of migraine and tension-type headache was 10.5% and 18.6%, respectively. Both migraine and TTH were significantly associated with self-reported problem behaviour in univariable logistic regression analyses. Additionally, migraine was associated with reduced sleep duration, and both sleep and behaviour problems remained significant after multivariable analyses. TTH was also significantly associated with antenatal maternal smoking, higher body fat, and being bullied. For TTH, problem behaviour measured at ages 3.5 and 11 years both remained significant after multivariable analysis. Being born small for gestational age was not associated with either headache group.

CONCLUSIONS

Although they share some commonality, migraine and tension-type headache are separate entities in childhood with different developmental characteristics. The association between primary headache and problem behaviour requires further investigation.