Patient headache questionnaires can improve headache diagnosis and treatment in children.

OBJECTIVE: To examine trends in diagnosis of headache and migraine in a large pediatric neurology cohort, and test whether an electronic health record (EHR)-integrated headache questionnaire can increase specificity of diagnosis and likelihood of prescribing migraine treatment. BACKGROUND: Under-diagnosis of migraine contributes to the burden of disease. As we founded our Pediatric Headache Program in 2013, we recognized that the proportion of patients with headache who were given a diagnosis of migraine was much lower than expected. METHODS: We developed a patient headache questionnaire, initially on paper (2013-2014), then in an electronic database (2014-2016), and finally integrated into our electronic health record (pilot: 2016, full: May 2017). We compared diagnoses and prescribed treatments for new patients who were given a headache diagnosis, looking at trends in the proportion of patients given specific diagnoses (migraine, etc.) versus the non-specific diagnosis, "headache." Next, we conducted a prospective cohort study to test for association between provider use of the form and the presence of a specific diagnosis, then for an association between specific diagnosis and prescription of migraine treatment. RESULTS: Between July 2011 and December 2022 the proportion of new headache patients who were given a diagnosis of migraine increased 9.7% and non-specific headache diagnoses decreased 21.0%. In the EHR cohort (June 2017-December 2022, n = 15,122), use of the provider form increased the rate of specific diagnosis to 87.2% (1839/2109) compared to 75.5% (5708/7560) without a patient questionnaire, nearly doubling the odds of making a specific diagnosis (odds ratio [OR] 1.90, 95% confidence interval [CI]: 1.65-2.19). Compared to those given only a non-specific headache diagnosis who were prescribed a migraine therapy 53.7% (1766/3286) of the time, 75.3% (8914/11836) of those given a specific diagnosis received a migraine therapy, more than doubling the odds of prescription (OR 2.39, 95% CI: 2.20-2.60). CONCLUSIONS: Interventions to improve specificity of diagnosis were effective and led to increased rates of prescription of migraine treatments. These results have been sustained over several years. This headache questionnaire was adapted into the Foundation system of EpicCare, so it is broadly available as a clinical and research tool for institutions that use this EHR software.

Development of a text message-based headache diary in adolescents and children.

BACKGROUND: International guidelines recommend diaries in migraine trials for prospective collection of headache symptoms. Studies in other patient populations suggest higher adherence with electronic diaries instead of pen-and-paper. This study examines the feasibility of a text message-based (texting) diary for children and adolescents with headache. METHODS: This is a secondary analysis of data from a study validating a pediatric scale of treatment expectancy. We developed a Health Insurance Portability and Accountability Act-compliant texting diary collecting headache characteristics, medication use, and disability with 3-5 core daily questions for 4 or 12 weeks depending on headache treatment. Adherence was incentivized. RESULTS: 93 participants consented to the expectancy study. Five participants opted for a paper diary for follow-up. 88 participants chose the texting diary with 28 4-week and 60 12-week participants. Five participants did not complete the enrollment visit. Of those remaining 83, 89% of 4-week and 93% of 12-week participants responded on at least 80% of days. On average, participants fully completed 88% (4-week cohort) and 90% (12-week) of diary entries. CONCLUSIONS: Text messages are a promising method for collecting patient-reported data. Adherence was similar to that reported for paper diaries in other pediatric migraine trials, but time-stamped entries ensure real-time data collection.

Trigeminal Pain Responses in Obese ob/ob Mice Are Modality-Specific.

How obesity exacerbates migraine and other pain disorders remains unknown. Trigeminal nociceptive processing, crucial in migraine pathophysiology, is abnormal in mice with diet induced obesity. However, it is not known if this is also true in genetic models of obesity. We hypothesized that obese mice, regardless of the model, have trigeminal hyperalgesia. To test this, we first evaluated trigeminal thermal nociception in leptin deficient (ob/ob) and control mice using an operant thermal assay. Unexpectedly, we found significant hypoalgesia in ob/ob mice. Because thermal hypoalgesia also occurs in mice lacking the transient receptor potential vanilloid 1 channel (TRPV1), we tested capsaicin-evoked trigeminal nociception. Ob/ob and control mice had similar capsaicin-evoked nocifensive behaviors, but ob/ob mice were significantly less active after a facial injection of capsaicin than were diet-induced obese mice or lean controls. Conditioned place aversion in response to trigeminal stimulation with capsaicin was similar in both genotypes, indicating normal negative affect and pain avoidance. Supporting this, we found no difference in TRPV1 expression in the trigeminal ganglia of ob/ob and control mice. Finally, we assessed the possible contribution of hyperphagia, a hallmark of leptin deficiency, to the behavior observed in the operant assay. Ob/ob and lean control mice had similar reduction of intake when quinine or capsaicin was added to the sweetened milk, excluding a significant contribution of hyperphagia. In summary, ob/ob mice, unlike mice with diet-induced obesity, have trigeminal thermal hypoalgesia but normal responses to capsaicin, suggesting specificity in the mechanisms by which leptin acts in pain processing.

Heat hyperalgesia and mechanical hypersensitivity induced by calcitonin gene-related peptide in a mouse model of neurofibromatosis.

This study examined whether mice with a deficiency of neurofibromin, a Ras GTPase activating protein, exhibit a nociceptive phenotype and probed a possible contribution by calcitonin gene-related peptide. In the absence of inflammation, Nf1+/- mice (B6.129S6 Nf1/J) and wild type littermates responded comparably to heat or mechanical stimuli, except for a subtle enhanced mechanical sensitivity in female Nf1+/- mice. Nociceptive phenotype was also examined after inflammation induced by capsaicin and formalin, which release endogenous calcitonin gene-related peptide. Intraplantar injection of capsaicin evoked comparable heat hyperalgesia and mechanical hypersensitivity in Nf1+/- and wild type mice of both genders. Formalin injection caused a similar duration of licking in male Nf1+/- and wild type mice. Female Nf1+/- mice licked less than wild type mice, but displayed other nociceptive behaviors. In contrast, intraplantar injection of CGRP caused greater heat hyperalgesia in Nf1+/- mice of both genders compared to wild type mice. Male Nf1+/- mice also exhibited greater mechanical hypersensitivity; however, female Nf1+/- mice exhibited less mechanical hypersensitivity than their wild type littermates. Transcripts for calcitonin gene-related peptide were similar in the dorsal root ganglia of both genotypes and genders. Transcripts for receptor activity-modifying protein-1, which is rate-limiting for the calcitonin gene-related peptide receptor, in the spinal cord were comparable for both genotypes and genders. The increased responsiveness to intraplantar calcitonin gene-related peptide suggests that the peripheral actions of calcitonin gene-related peptide are enhanced as a result of the neurofibromin deficit. The analgesic efficacy of calcitonin gene-related peptide receptor antagonists may therefore merit investigation in neurofibromatosis patients.

Validation of four reference genes for quantitative mRNA expression studies in a rat model of inflammatory injury.

BACKGROUND: Real-time quantitative PCR (qPCR) is a technique frequently used to measure changes in mRNA expression. To ensure validity of experimental findings, it is important to normalize the qPCR data to reference genes that are stable and unaffected by the experimental treatment to correct for variability among samples. Unlike in some models of neuropathic pain, reference genes for models of inflammatory injury have not been validated. This study examined four candidate reference genes in an effort to identify and validate optimal genes for normalization of transcriptional changes occurring in the dorsal horn of the spinal cord and the rostral ventromedial medulla (RVM) following intraplantar injection of complete Freund's adjuvant (CFA). RESULTS: The expression of hypoxanthine phosphoribosyltransferase 1 (Hprt1), beta-actin (Actb), mitogen-activated protein kinase 6 (Mapk6), and beta-2-microglobulin (B2m) was quantified in the dorsal horn and RVM of rats four days or two weeks after intraplantar injection of CFA or saline. The range of expression levels among these four genes differed by as much as 16-fold within the dorsal horn and the RVM. All four of these reference genes were stably expressed in both tissues and did not differ between saline and CFA-treated animals. Analyses using the statistical algorithms in geNorm and NormFinder programs determined that Mapk6 was the most stable gene and recommended the combination of Mapk6 and Actb, or Mapk6 and Hprt1, in such experimental conditions. CONCLUSIONS: This study validated the four genes Hprt1, Actb, Mapk6 or B2m and showed that any one or combination of two of them are good reference genes for normalization of mRNA expression in qPCR experiments in the spinal cord and RVM in the CFA model of inflammatory injury.

Spinal nerve ligation decreases γ-aminobutyric acidB receptors on specific populations of immunohistochemically identified neurons in L5 dorsal root ganglion of the rat.

This study examined the distribution of γ-aminobutyric acid (GABA)(B) receptors on immunohistochemically identified neurons, and levels of GABA(B(1)) and GABA(B(2)) mRNA, in the L4 and L5 dorsal root ganglia (DRG) of the rat in the absence of injury and 2 weeks after L5 spinal nerve ligation. In uninjured DRG, GABA(B(1)) immunoreactivity colocalized exclusively with the neuronal marker (NeuN) and did not colocalize with the satellite cell marker S-100. The GABA(B(1)) subunit colocalized to >97% of DRG neurons immunoreactive (IR) for neurofilament 200 (N52) or calcitonin gene-related peptide (CGRP), or labeled by isolectin B4 (IB4). Immunoreactivity for GABA(B(2)) was not detectable. L5 spinal nerve ligation did not alter the number of GABA(B(1)) -IR neurons or its colocalization pattern in the L4 DRG. However, ligation reduced the number of GABA(B(1)) -IR neurons in the L5 DRG by ≈38% compared with sham-operated and naïve rats. Specifically, ligation decreased the number of CGRP-IR neurons in the L5 DRG by 75%, but did not decrease the percent colocalization of GABA(B(1)) in those that remained. In the few IB4-positive neurons that remained in the L5 DRG, colocalization of GABA(B(1)) -IR decreased to 75%. Ligation also decreased levels of GABA(B(1)) and GABA(B(2)) mRNA in the L5, but not the L4 DRG compared with sham-operated or naïve rats. These findings indicate that the GABA(B) receptor is positioned to presynaptically modulate afferent transmission by myelinated, unmyelinated, and peptidergic afferents in the dorsal horn. Loss of GABA(B) receptors on primary afferent neurons may contribute to the development of mechanical allodynia after L5 spinal nerve ligation.

Genetic enhancement of calcitonin gene-related Peptide-induced central sensitization to mechanical stimuli in mice.

UNLABELLED: Calcitonin gene-related peptide (CGRP) is a key player in migraine. To address the role of CGRP in mechanical allodynia, which is a common feature of migraine, we used CGRP-sensitized transgenic mice. These mice have elevated nervous-system expression of the human receptor activity-modifying protein-1 (hRAMP1) subunit of the CGRP receptor. Under baseline conditions, the nestin/hRAMP1 mice and control littermates had similar hindpaw withdrawal thresholds to von Frey filaments. The effect of CGRP was tested using a filament that elicited a withdrawal response on 20% of its presentations. Following intrathecal injection of 1 nmol CGRP in the nestin/hRAMP1 mice, the response frequency was 80% within 30 minutes. The antagonist CGRP(8-37) blocked the increased response. In control littermates, a 5-fold higher dose of CGRP was required to elicit a similar response. In contrast to intrathecal injection, peripheral CGRP did not increase the mechanical responses. Intraplantar injection of capsaicin was used to test the efficacy of endogenous CGRP. Capsaicin increased mechanical responses in the nestin/hRAMP1 and control mice, although a higher dose was required in controls. In contrast to control mice, there was also a contralateral paw response in nestin/hRAMP1 mice, which is consistent with central sensitization. PERSPECTIVE: In this study we show central CGRP-induced mechanical allodynia that is enhanced by overexpression of RAMP1 in nervous system. These data suggest that hypersensitivity to CGRP could be a potential mechanism underlying central sensitization in migraine and point to CGRP-receptor antagonists as a possible therapy for other pain disorders.

Sensitization of calcitonin gene-related peptide receptors by receptor activity-modifying protein-1 in the trigeminal ganglion.

The neuropeptide calcitonin gene-related peptide (CGRP) from the trigeminal ganglion has been established as a key player in the pathogenesis of migraine. In this study, we provide evidence that the responsiveness of neuronal CGRP receptors is strongly enhanced in vitro and in vivo by expression of human receptor activity-modifying protein-1 (hRAMP1), an obligatory subunit of the CGRP receptor. We first demonstrated that activation of CGRP receptors on cultured trigeminal ganglion neurons increased endogenous CGRP mRNA levels and promoter activity. The promoter activation was cAMP dependent and blocked by the antagonist BIBN4096BS [1-piperidinecarboxamide, N-[2-[[5-amino-l-[[4-(4-pyridinyl)-l-piperazinyl]carbonyl]pentyl]amino]-1-[(3,5-dibromo-4-hydroxyphenyl)methyl]-2-oxoethyl]-4-(1,4-dihydro-2-oxo-3(2H)-quinazolinyl)], a new antimigraine drug. Gene transfer using an adenoviral hRAMP1 expression vector increased the maximal production of cAMP by 1.8 +/- 0.2-fold and decreased the EC50 to 2.3 +/- 0.8 nM from 9.0 +/- 5.9 nM and 15.6 +/- 5.2 nM in uninfected and control-infected cultures, respectively. To establish whether RAMP1 is limiting in vivo as indicated from the culture studies, a transgenic mouse expressing hRAMP1 in the nervous system was generated. After CGRP injection into the whiskerpad, the hRAMP1 transgenic mice displayed 2.2 +/- 0.2-fold greater plasma extravasation, which is a measure of neurogenic inflammation. These results demonstrate that RAMP1 is functionally rate limiting for CGRP receptor activity in the trigeminal ganglion, which raises the possibility that elevated RAMP1 might sensitize some individuals to CGRP actions in migraine.