Chronic daily headache: nosology and pathophysiology

The effect of simultaneous administration of occipital nerve block and cervical myofascial trigger point injection (MTrPI) on headache parameters in chronic migraine patients

BACKGROUND AND AIM

Peripheral myofascial mechanisms have been identified as contributors to migraine pathophysiology. The specific comorbid relationship between migraine and cervical trigger points may exacerbate the occurrence and severity of migraine attacks. Trigger point injections (TPIs) are frequently employed to address headaches and alleviate migraine symptoms. The current study explores the impact of concurrent myofascial trigger point injection (MTrPI) and occipital nerve block (greater occipital nerve block [GONB] + lesser occipital nerve block [LONB]) on the severity of headaches and the number of migraine attacks in individuals with chronic migraine (CM) and cervical myofascial trigger points (MTrPs), with a comparison of occipital nerve block alone (GONB + LONB). During trigger point examination and injection, trapezius, levator scapulae, splenius capitis, temporalis, and sternocleidomastoid muscles were targeted. We planned the treatment based on whether they were in the muscle groups we determined, rather than the number of trigger points.

MATERIALS AND METHOD

This study enrolled 62 individuals experiencing CM with bilateral headache and cervical MTrP who sought care at the Algology Unit within the Departments of Neurology and Physical Therapy and Rehabilitation at Siirt Training and Research Hospital between 2020 and 2022. The CM cohort was stratified into two groups: group 1 received trigger point injections (TrPI), while group 2 underwent concurrent bilateral occipital nerve block (GONB + LONB) and TrPI. Both groups underwent three treatment sessions with bupivacaine 0.5% (1 ml = 5 mg) in weeks 1, 2, and 4. Visual analog scale (VAS) was used to measure the patients' pain intensity. The evaluation included the assessment of the monthly migraine frequency and visual analog scale (VAS) p score for pain before treatment (BT) and after treatment (AT), conducted at baseline and during follow-up visits. Analysis of the data was conducted utilizing IBM SPSS Statistics for Windows version 28.0 software.

RESULTS

Among patients diagnosed with CM and MTrPs, 32 individuals (51.6%) underwent GONB and LONB, while 30 patients (48.4%) received simultaneous GONB, LONB, and cervical MTrPI. Within the entire sample, 51 participants (82.3%) were female, and 11 (17.7%) were male, with a mean age of 32.81 ± 10.75 years. With an average age of 32.81 ± 10.75 years, there was no statistically significant variance between the two groups (p = 0.516). Of the total cohort, 45 individuals (72.6%) reported experiencing headaches persisting for 12 months or longer. Among CM patients, 80% had active trigger points, while 20% had latent trigger points. No statistically significant difference was observed between the groups concerning TrPs (p = 0.158), and the distribution of TrPs was homogenous across the two groups. In group 1, the median (min-max) monthly frequency of migraines reduced from 18.5 days (range: 15.0 to 25.0 days) before treatment to 12.0 days (range: 7.0 to 17.0 days) after treatment (p = 0.000). In group 2, the median monthly frequency of migraines reduced from 16.5 days (range: 15.0 to 22.0 days) before treatment to 4.0 days (range: 2.0 to 8.0 days) after treatment (p = 0.000). The median (min-max) VAS score in group 1 was 8.0 (range: 5.0 to 9.0) before treatment, 4.0 (range: 2.0 to 6.0) at week 1, and 5.0 (range: 4.0 to 8.0) at week 4 (p = 0.000). In group 2, the median VAS score was 7.0 (range: 5.0 to 9.0) before treatment, 0.0 (range: 0.0 to 0.3) at week 1, and 2.0 (range: 0.0 to 0.3) at week 4 (p = 0.000). There were significant distinctions between the groups in terms of both the monthly count of migraine days and the severity of headaches (p = 0.000).

CONCLUSION

The combination of repeated MTrPIs and ONB proves more effective than ONB alone in managing patients with CM and cervical MTrP. In patients with CM, performing TrPs examination and adding treatments for this may contribute to the treatment. In cases where patients endure prolonged episodes of headache associated with chronic migraine, the inclusion of trigger point injections alongside peripheral nerve blocks may offer enhanced therapeutic benefits.

Subsume Pediatric Headaches in Psychiatric Disorders? Critiques on Delphic Nosology, Diagnostic Conundrums, and Variability in the Interventions

PURPOSE OF REVIEW

Tension-type headache (TTH) continues to be the most prevalent type of headache across all age groups worldwide, and the global burden of migraine and TTH together account for 7% of all-cause years lived with disability (YLDs). TTH has been shown to have a prevalence of up to 80% in several studies and presents a wide range and high variability in clinical settings. The aim of this review is to identify gaps in diagnostics, nosology, and variability in the treatment of children and adolescents who present with headaches without an identifiable etiology.

RECENT FINDINGS

Migraine and TTH have been debated to have more similarities than distinctions, increasing chances of misdiagnosis and leading to significant cases diagnosed as probable TTH or probable migraine. The lack of specificity and sensitivity for TTH classification often leads to the diagnosis being made by negating associated migraine symptoms. Although pathology is not well understood, some studies have suggested a neurological basis for TTH, in need of further validation. Some research indicates that nitric oxide signaling plays an integral part in the pain mechanisms related to TTH. Analgesics and non-steroidal anti-inflammatories are usually the first lines of treatment for children with recurring headaches, and additional treatment options include medication and behavioral therapies. With high prevalence and socioeconomic burden among children and adolescents, it's essential to further study Tension-type headaches and secondary headaches without known cause and potential interventions. Treatment studies involving randomized controlled trials are also needed to test the efficacy of various treatments further.

Four Decades of Occipital Nerve Stimulation for Headache Disorders: A Systematic Review

PURPOSE OF REVIEW

Chronic headaches are a significant source of disability worldwide. Despite the development of conventional strategies, a subset of patients remain refractory and/or experience side effects following these treatments. Hence, occipital nerve stimulation (ONS) should be considered as an alternative strategy for intractable chronic headaches. This review aims to provide a comprehensive overview of the effectiveness, safety, mechanisms and practical application of ONS for the treatment of headache disorders.

RECENT FINDINGS

Overall response rate of ONS is 35.7-100%, 17-100%, and 63-100% in patients with cluster headache, chronic migraine and occipital neuralgia respectively. Regarding the long-term effectivity in all groups, 41.6-88.0% of patients remain responders after ≥ 18.3 months. The most frequently reported adverse events include lead migration/fracture (13%) and local pain (7.3%). Based on our results, ONS can be considered a safe and effective treatment for chronic intractable headache disorders. To support more widespread application of ONS, additional research with larger sample sizes should be conducted.

Medication-overuse headache: a narrative review

Medication-overuse headache (MOH), which potentially involves 1-2% of the population, is defined as a headache, on ≥ 15 days a month affected, along with overuse of one or other acute attack medications. MOH presents with significant challenges in the headache community, particularly in clinical settings raising various questions about its pathophysiology. Through a review of the current literature and our clinical experience, we have explored the mechanisms through which MOH may occur, provide an understanding of the current state of treatment and detail some possible views on the understanding and treatment of this condition. We evaluate the variations in treatment methods offered globally and understanding of the disorder. Above all interventions, patient education is crucial, which is underscored by an analysis of the academic publications. Given the condition is preventable, early intervention is imperative and patient awareness is highlighted as key. Globally, there is no uniform treatment methodology, which may be advantageous as approaches need to take local circumstances into account.

Functional representation of trigeminal nociceptive input in the human periaqueductal gray

The periaqueductal gray (PAG) is located in the mesencephalon in the upper brainstem and, as part of the descending pain modulation, is considered a crucial structure for pain control. Its modulatory effect on painful sensation is often seen as a systemic function affecting the whole body similarly. However, recent animal data suggest some kind of somatotopy in the PAG. This would make the PAG capable of dermatome-specific analgesic function. We electrically stimulated the three peripheral dermatomes of the trigemino-cervical complex and the greater occipital nerve in 61 humans during optimized brainstem functional magnetic resonance imaging. We provide evidence for a fine-grained and highly specific somatotopic representation of nociceptive input in the PAG in humans and a functional connectivity between the individual representations of the peripheral nerves in the PAG and the brainstem nuclei of these nerves. Our data suggest that the downstream antinociceptive properties of the PAG may be rather specific down to the level of individual dermatomes.

Potential genetic polymorphism of matrix metalloproteinase (MMP)-9 in Iranian migraine patients with Toxoplasma gondii infection

Toxoplasma gondii is an intracellular protozoan parasite that causes neuroinflammation in the brain and a constant need for peripheral leukocyte migration. Matrix metalloproteinase 9 (MMP-9) can play a major role in this neuroinflammation and be implicated in some neurological disorders, such as migraines. Therefore, the genetic polymorphism evaluation of MMP-9 in migraine patients with T. gondii infection was performed. One hundred fourteen migraine patients and 114 healthy controls were evaluated for the presence of anti-Toxoplasma IgG antibodies. Seventy-two migraine patients and 40 healthy controls were randomly selected for assessment of the MMP 9-1562C/T genetic polymorphism. In the preliminary examination, 61 (53.5%) migraine patients and 43 (37.3%) healthy controls were positive for IgG antibodies, with a significant association between T. gondii seropositivity and migraine (OR = 1.90; 95% CI = 1.21-3.223; P = 0.012). Genetic distribution for the polymorphism was not in Hardy-Weinberg equilibrium in cases but showed no significant variation in control groups (P = 0.03 and P = 0.180, respectively). A significant preponderance of the CT + TT genotype was found in migraine subjects compared to controls (P = 0.042) (OR, 1.77, CI, 1.013-2.229). The homozygote muted allele TT had a higher rate in migraine patients (6.9%). There were significant differences in CT + TT genotype between T. gondii positive and negative migraine patients (P = 0.024), but T allele frequencies had no significant variation (OR 1.7 CI, 1.084-2.44 and 0.42 CI, 0.044-3.97, respectively). In conclusion, the results may provide the first evidence for the involvement of the MMP-9 gene polymorphism in the mechanism of migraine pathology following Toxoplasma infection.

Chronic migraine and medication overuse

Though clearly described as far back as the 17th century, chronic migraine has defied precise categorization and has continued to develop as an important diagnostic concept with significant societal impact. Worldwide prevalence is estimated to be between 1% and 3%, and these patients form a dynamic group cycling between chronic and episodic migraine. Theories of pathogenesis are developing supported by recent imaging and other findings. Of the many determinants of progression to chronic migraine, overuse of acute abortive headache medications may be one of the most important modifiable factors. Treatment strategies, in addition to educational measures, have included various preventive migraine medications such as topiramate, valproate, and onabotulinumtoxinA. CGRP monoclonal antibodies are efficacious for the management of chronic migraine both with and without medication overuse.

CGRP antibody therapy in patients with drug resistant migraine and chronic daily headache: a real-world experience

BACKGROUND

Calcitonin gene-related peptide (CGRP) (receptor) antibodies (erenumab, fremanezumab and galcanezumab) are increasingly used in prophylactic treatment of migraine. In the approval studies, severely affected patients with migraine and chronic daily headache without any headache free days were excluded. Thus, less is known about the effectiveness of CGRP antibody treatment in this cohort.

METHODS

Clinical routine data of 32 patients with migraine and daily headache were analysed after three months of treatment with a CGRP antibody (16 erenumab, 7 galcanezumab, 9 fremanezumab), including changes of monthly headache days (MHD) monthly migraine days (MMD) and monthly acute medication intake (AMD) as well as migraine characteristics. Statistical analysis was performed with the Wilcoxon-Test. Migraine characteristics were analysed descriptively.

RESULTS

The number of MHD was significantly reduced (mean reduction (standard error), p-value): (-4.2 (1.3), p = 0.009) as well as MMD (-4.3 (1.6), p = 0.033). Four patients (13 %) reached a 50 % reduction regarding MHD and 8 patients (25 %) regarding MMD, migraine duration and intensity improved under therapy.

CONCLUSIONS

Despite the low responder rate, CGRP antibodies can be effective at least in a few cases of severely affected patients with drug resistant migraine and chronic daily headache.

TRIAL REGISTRATION

Retrospective registered.

Fremanezumab autoinjector pen for the prevention of migraine

Ajovy (fremanezumab, Teva Pharmaceuticals, Israel) is a fully humanized monoclonal antibody that selectively binds both isoforms of the calcitonin gene-related peptide. Calcitonin gene-related peptide is a 37-amino acid neuropeptide involved in central and peripheral pathophysiological events in migraine. It is indicated for prophylaxis of migraine in adults who have at least four migraine days per month, and can be administered as a subcutaneous injection using an autoinjector device, with two dosing options: 225 mg once a month or 675 mg quarterly. In this article, I present data from Phase III clinical trials of fremanezumab in episodic and chronic migraine, in which fremanezumab demonstrated efficacy and had a favorable tolerability profile, with no serious treatment-related adverse events.

Genetics, pathophysiology, diagnosis, treatment, management, and prevention of migraine

Migraine is a neurological ailment that is characterized by severe throbbing unilateral headache and associated with nausea, photophobia, phonophobia and vomiting. A full and clear mechanism of the pathogenesis of migraine, though studied extensively, has not been established yet. The current available information indicates an intracranial network activation that culminates in the sensitization of the trigemino-vascular system, release of inflammatory markers, and initiation of meningeal-like inflammatory reaction that is sensed as headache. Genetic factors might play a significant role in deciding an individual's susceptibility to migraine. Twin studies have revealed that a single gene polymorphism can lead to migraine in individuals with a monogenic migraine disorder. In this review, we describe recent advancements in the genetics, pathophysiology, diagnosis, treatment, management, and prevention of migraine. We also discuss the potential roles of genetic and abnormal factors, including some of the metabolic triggering factors that result in migraine attacks. This review will help to accumulate current knowledge about migraine and understanding of its pathophysiology, and provides up-to-date prevention strategies.

Rhynchophylline attenuates migraine in trigeminal nucleus caudalis in nitroglycerin-induced rat model by inhibiting MAPK/NF-кB signaling

Migraine causes severe health and social issues worldwide. Rhynchophylline (Rhy) is one of the major active components of Uncaria rhynchophylla that is used for the treatment of headache in Traditional Chinese Medicine. In the current study, the effect of Rhy on nitroglycerin (NTG)-induced migraine was assessed and the associated mechanism was also explored to explain its function. Rats were pre-treated with Rhy of two doses (10 mg/kg and 30 mg/kg) and then subjected to NTG to induce migraine symptoms. Thereafter, the electroencephalogram (EEG) signaling, spontaneous behaviors, levels of indicators related to oxidative stress, and expression of calcitonin gene-related peptide (CGRP) were measured to assess the anti-migraine function of Rhy. Moreover, the activities of MAPK/NF-κB pathway under the administrations of Rhy were also detected. The results showed that NTG induced EEG and behavior disorders in rats, which was associated with the initiation of oxidative stress and increased expression of CGRP. Nevertheless, the pre-treatments with Rhy attenuated the damages induced by NTG by reversing the levels of all the above indicators. The results of western blotting demonstrated that the anti-migraine effect of Rhy was accompanied by the inhibition of MAPK/NF-кB pathway. The findings outlined in the current study revealed an alternative mechanism of Rhy in protecting brain tissues against migraine: the agent exerted its effect by suppressing MAPK/NF-кB pathway, which would ameliorate impairments associated with migraine.

Oral transmucosal delivery of naratriptan

Naratriptan (NAR) is currently used as the hydrochloride salt (NAR.HCl) for the treatment of migraine and is available in tablet dosage forms for oral administration. Buccal drug delivery offers a number of advantages compared with conventional oral delivery including rapid absorption, avoidance of first pass metabolism and improved patient compliance. We have previously prepared and characterised the base form of NAR and shown that it has more favourable properties for buccal delivery compared with NAR.HCl. This study describes the design and evaluation of a range of formulations for oral transmucosal delivery of NAR base. Permeation studies were conducted using excised porcine buccal tissue mounted in Franz cells. Of the neat solvents examined, Transcutol^® P (TC) showed the greatest enhancement effects and was the vehicle in which NAR was most soluble. The mechanisms by which TC might promote permeation were further probed using binary systems containing TC with either buffer or Miglyol 812^® (MG). Mass balance studies were also conducted for these systems. The permeation of TC as well as NAR was also monitored for TC:MG formulations. Overall, TC appears to promote enhanced membrane permeation of NAR because of its rapid uptake into the buccal tissue. Synergistic enhancement of buccal permeation was observed when TC was combined with MG and this is attributed to the increased thermodynamic activity of NAR in these formulations. Significantly enhanced permeation of NAR was achieved for TC:MG and this was also associated with less TC remaining on the tissue or in the tissue at the end of the experiment. To our knowledge this is the first report where both enhancer and active have been monitored in buccal permeation studies. The findings underline the importance of understanding the fate of vehicle components for rational formulation design of buccal delivery systems.

Topiramate in the Treatment of Chronic Migraine

The purpose of this study was to evaluate the efficacy of topiramate in the treatment of chronic migraine. This was a double-blind, randomized, placebo controlled, parallel-group study. Patients suffering from chronic migraine with analgesic overuse were randomly assigned in a 1 : 1 ratio to receive topiramate or placebo. Following a baseline phase of eight weeks, the study drug was titrated in 25-mg increments over one week to 50 mg daily. Titration phase was followed by a 8-week maintenance phase. Number of days with headache during a 28-day period was the efficacy variable. At baseline, there was no difference in the number of days with headache between patients treated with topiramate and those treated with placebo (mean ± SD: 20.9 ± 3.2 and 20.8 ± 3.2, respectively). During the last 4 week-maintenance phase, topiramate-treated patients experienced a significantly lower 28-day headache frequency in comparison to those treated with placebo (mean number of days with headache ± SD: 8.1 ± 8.1 vs. 20.6 ± 3.4, P < 0.0007). Topiramate at low doses proved to be an effective therapeutic approach to reduce headache frequency in patients with chronic migraine and analgesic overuse.

Chronic Daily Headache in Children and Adolescents: A Multi-Faceted Syndrome

Chronic daily headache (CDH) is a multi-faceted, often complex pain syndrome in children and adolescents. Chronic daily headache may be primary or secondary. Chronic migraine and chronic tension-type are the most frequent subtypes. Chronic daily headache is co-morbid with adverse life events, anxiety and depressive disorders, possibly with other psychiatric disorders, other pain syndromes and sleep disorders; these conditions contribute to initiating and maintaining CDH. Hence, early management of episodic headache and treatment of associated conditions are crucial to prevention. There is evidence for the benefit of psychological therapies, principally relaxation and cognitive behavioral, and promising information on acupuncture for CDH. Data on drug treatment are based primarily on open label studies. The controversies surrounding CDH are discussed and proposals for improvement presented. The multifaceted nature of CDH makes it a good candidate for a multi-axial classification system. Such an approach should facilitate biopsychosocial management and enhance consistency in clinical research.

Valproate ameliorates nitroglycerin-induced migraine in trigeminal nucleus caudalis in rats through inhibition of NF-кB

BACKGROUND

As a complex nervous system disease, migraine causes severe healthy and social issues worldwide. Valproate (VPA) is a widely used treatment agent against seizures and bipolar disorder, and its function to alleviate damage due to migraine has also been verified in clinical investigations. However, the mechanism underlying the protective effect of VPA against migraine remains poorly revealed. In the current study, the major purpose was to uncover the mechanism which drove VPA to antagonize migraine.

METHODS

Nitroglycerin (NTG) was employed to induce a migraine model in rats and the migraine animals were exposed to treatment of VPA of different doses. Thereafter, the levels of indicators related to oxidative stress were measured and used to evaluate the anti-oxidant potential of VPA. The expression of calcitonin gene-related peptide (CGRP) and c-Fos was also quantified with ELISA and immunohistochemistry, respectively. Western blotting and electrophoretic mobility shift assays (EMSA) were conducted to explore the effect of VPA treatment on NF-кB pathway.

RESULTS

NTG induced the activation of oxidative stress and led to migraine in model animals, but pre-treatment with VPA attenuated the damage due to migraine attack in brain tissues. The level of lipid peroxidation was significantly reduced while the prodcution of anti-oxidant factors was restored. Furthermore, expressions of CGRP and c-Fos, which represented the neuronal activation, were also down-regulated by VPA. The results of western blotting and EMSA demonstrated that the above mentioned effect of VPA acted through the inhibition of NF-кB pathway.

CONCLUSIONS

Although controversies on the effect of VPA on NF-кB pathway existed, our study revealed an alternative mechanism of VPA in protecting against migraine, which would promote the development of therapeutic strategies of migraine.

The diagnosis and treatment of chronic migraine

Migraine is the most common disabling brain disorder. Chronic migraine, a condition characterized by the experience of migrainous headache on at least 15 days per month, is highly disabling. Patients with chronic migraine present to primary care, are often referred for management to secondary care, and make up a large proportion of patients in specialist headache clinics. Many patients with chronic migraine also have medication overuse, defined as using a compound analgesic, opioid, triptan or ergot derivative on at least 10 days per month. All doctors will encounter patients with chronic headaches. A basic working knowledge of the common primary headaches, and a rational manner of approaching the patient with these conditions, allows a specific diagnosis of chronic migraine to be made quickly and safely, and by making this diagnosis one opens up a substantial number of acute and preventive treatment options. This article discusses the current state of management of chronic migraine.

MRI in headache

Headaches are described as primary, where no contributing cause is found, or secondary, where a discrete lesion or other condition has triggered the phenotype. Primary headache is a common condition; migraine causes much of the morbidity in this population, at great personal and economic cost. The decision to use MRI is a common dilemma facing clinicians, particularly as primary headache phenotypes can be triggered by secondary causes. Studies demonstrate that there is no appreciable difference in the frequency of pathological and incidental findings in common headache populations compared with the general community. Imaging is therefore not routinely required where a primary headache diagnosis can be made. Clinicians must be aware of the risk of manufacturing morbidity in uncovering incidental and nonsignificant imaging changes. However, patients demonstrating 'red flags' on medical history and examination do require imaging to help exclude a secondary cause of symptoms. Other headache phenotypes, such as the trigeminal autonomic cephalalgias, also generally require MRI.

The outcomes for nasal contact point surgeries in patients with unsatisfactory response to chronic daily headache medications

The nasal contact point may act as a trigger point or peripheral enhancer in patients with chronic daily headaches. A total of 42 patients had unsatisfactory response to medical treatment for chronic daily headache with radiologic evidence of nasal contact point. Of them, 12 (28.5%) patients were positive for the local anesthetic test. Those patients were operated upon to separate this contact by either septoplasties or submucous resections with or without partial turbinectomies. The mean headache frequency was reduced from 22 to 7 days/month. The mean headache severity was reduced from 5.6 to 2.4. Eight (19%) patients became completely free from headache and its medications, six (75%) of them were positive for local anesthetic test. The patients were satisfied with postoperative monotherapy, or headache severity and frequency could be tolerated without medications in 26 (62%) patients. There was no improvement in seven (16.6%) patients and only one patient (2%) became worse. The overall satisfaction was 83 and 81% for positive and negative anesthetic tests, respectively. The average monthly medication cost was reduced from $85 to 32. Nasal contact point surgery for chronic daily headache patients can satisfy them compared to previously unsatisfactory medications. Nasal contact point may contribute to potentiating or triggering chronic daily headache.

Topiramate in migraine progression

Increasing evidence shows that migraine, typically considered as an episodic disease, is a chronic and, in some patients, progressive disorder. Among neuromodulators used for migraine prevention, topiramate has a high level of evidence-based efficacy. Through its wide range of mechanisms of action topiramate increases the activation threshold resulting in neuronal stabilization and thereby reducing cortical neurons hyperexcitability, which is believed to be an important electrophysiological feature underlying the pathogenesis of epilepsy and migraine. Recent studies show that migraineurs have subclinical structural brain changes and persistent alteration of pain perception, in some cases correlated with the duration of the disease and the frequency of attacks that might play a role in the transformation of episodic migraine to chronic forms. An early and prolonged preventive treatment might reduce the risk of such transformation. Recent evidence suggests that topiramate, by reducing migraine frequency and use of acute medication, may prevent the negative progression of migraine. Furthermore, two recently completed multicenter, randomised, placebo-controlled trials have shown that treatment with topiramate 100 mg/day is effective and well tolerated in patients already progressed to chronic migraine and difficult to treat conditions associated with medication-overuse. Topiramate seems to be a preventive treatment, which might be able to act at different levels of the migraine cycle: reduction of frequency in episodic migraine, prevention, and treatment of chronic migraine.

Epidemiology, risk factors, and treatment of chronic migraine: a focus on topiramate

The term chronic daily headache refers to a heterogeneous group of headache disorders characterized by a frequency of headaches on > or = 15 days per month. Chronic migraine is a subtype of chronic daily headache. The prevalence of chronic migraine is approximately 1%. Baseline attack frequency and acute medication overuse have been identified as potential risk factors for the progression of migraine from an episodic disorder to a chronic condition. There is an unmet patient need for effective and safe treatments for patients with chronic migraine, but data from rigorous controlled trials are limited. Previous studies have demonstrated that topiramate is an effective and safe preventive treatment for episodic migraine. In addition, pilot studies have suggested the utility of topiramate for the prevention of chronic migraine. Two randomized, double-blind, placebo-controlled, multicenter trials investigating the efficacy and safety of topiramate in the treatment of patients with chronic migraine have recently been completed. This review presents comparative data from these 2 clinical trials, which suggest that topiramate at a dose of 100 mg daily is effective and generally well tolerated in chronic migraine.

Headache associated with pituitary tumors

The objective of this study is to analyze the presence of headache in pituitary tumors and their characteristics, the relationship between pituitary tumor size, biological type, local extension and intrasellar pressure (ISP). This is a prospective study, of 64 consecutive patients presenting with primary pituitary masses at Neuroendocrinological Department of General Hospital of Fortaleza from October 2005 to December 2006. We analyzed sex, age, headache (laterality, site, severity, quality, frequency, duration, associated symptoms, time of onset, trigger, alleviating factors and familial history) and tumor characteristics (type, size, quiasmatic compression, cavernous sinus invasion, sella turcica destruction, cystic or solid mass and ISP). We observed a statistic significant factor between pituitary tumor and tumor size, optic compression, sellar destruction, cavernous sinus invasion and ISP. Biochemical-neuroendocrine factors, mainly in prolactinomas, seem to be an important factor in the determination of headache. The presence of headache in pituitary tumor is related to a combination of factors, including ISP, tumor extension, relationship with the sellar structures, patient predisposition, familial history, and functional disturbance within the hypothalamo-pituitary axis.

Is migraine a neuropathic pain syndrome?

The understanding of migraine pathophysiology has evolved from the belief that migraine is a vascular disorder, to evidence that better defines migraine as a neurogenic disorder associated with secondary changes in brain perfusion. There is evidence to suggest that the early phase of migraine pain results from neurogenic inflammation affecting cranial blood vessels and dura. Allodynia, hyperalgesia, and expansion of nociceptive fields occur during most well-established migraine attacks. These clinical features of migraine are evocative of those traditionally associated with neuropathic pain. A hypothesis that defines migraine pain as a unique neuropathic pain disorder can imply the potential for neural plasticity and may provide insight into the mechanisms that underlie the transformation of episodic to chronic forms of migraine. The neuropathic pain model of migraine pathophysiology not only paves the way for mechanism-based treatment strategies that can improve the acute and preventive management of migraine attacks, but also opens the door for the discovery of novel therapeutic targets. It also lends momentum to an understanding of clinically intriguing topics such as opiate-induced hyperalgesia and medication-overuse headache (rebound headache), opioid resistance in the treatment of chronic headache, and disease modification in defending against the potential for migraine transformation.

Neurovascular pains: implications of migraine for the oral and maxillofacial surgeon

Epidemiologic studies have shown that migraine headaches are a common finding in the general population, often associated with a high degree of disability. Additionally, migraine has a reported comorbidity with other medical conditions, most notably with chronic pains, such as temporomandibular disorders. The pathophysiologic mechanisms involved with migraine are suggestive of an increased and prolonged hyperexcitability to stimuli, especially within the trigeminal distribution. Because migraine is mediated by branches of the trigeminal nerve it has the potential to mimic other types of pains, such as toothache or sinusitis. It is therefore recommended that oral and maxillofacial surgeons be familiar with the diagnostic criteria for migraine headaches to identify and appropriately treat such individuals who present to their clinics.

Chronic pain may change the structure of the brain

Recently, local morphologic alterations of the brain in areas ascribable to the transmission of pain were detected in patients suffering from phantom pain, chronic back pain, irritable bowl syndrome, fibromyalgia and two types of frequent headaches. These alterations were different for each pain syndrome, but overlapped in the cingulate cortex, the orbitofrontal cortex, the insula and dorsal pons. These regions function as multi-integrative structures during the experience and the anticipation of pain. As it seems that chronic pain patients have a common "brain signature" in areas known to be involved in pain regulation, the question arises whether these changes are the cause or the consequence of chronic pain. The author suggests that the gray matter change observed in chronic pain patients are the consequence of frequent nociceptive input and should thus be reversible when pain is adequately treated.

Neurostimulation in primary headache syndromes

Neurostimulation therapy involves the use of peripheral or central nerve electrical stimulation approaches for the treatment of medically intractable headache. Currently, for peripheral stimulation the main approach is that of occipital nerve stimulation, while for central stimulation deep-brain approaches with the target of the region of the posterior hypothalamic gray matter have been explored. Target conditions include migraine and the trigeminal autonomic cephalalgias: cluster headache, paroxysmal hemicrania and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing/cranial autonomic features (SUNCT/SUNA), as well as hemicrania continua. The initial results are encouraging and given the very significant disability of medically intractable primary headaches, this is a very promising area for patients and physicians alike.

Prognostic significance of personality profiles in patients with chronic migraine

BACKGROUND AND OBJECTIVE

The aim of this study was to assess whether the psychological profile may have prognostic significance in chronic migraine patients.

METHODS

The Minnesota Multiphasic Personality Inventory-2 was used for the psychological assessment of patients with chronic migraine to explore personality traits. Patients with psychiatric disease and medication overuse were excluded. One hundred and two patients completed the study. Migraine-related disability was measured using the Migraine Disability Assessment questionnaire at baseline (T(0)) and again after 2 years (T(1)), during which patients received prophylactic treatment for migraine. At T(1) patients were classified into those exhibiting significant improvement (group 1: scores reduced by at least 50%) and those with unsatisfactory changes in headache-related disability (group 2: scores reduced by less than 50%).

RESULTS

At T(1) 49 patients were in group 1 and 53 in group 2; at T(0), group 1 patients had significantly lower Minnesota Multiphasic Personality Inventory-2 scores in the neurotic (hypochondriasis: P < .01; depression: P < .001; hysteria: P < .01) and schizophrenia (P < .05) scales. None of the other variables studied, ie, age, sex, age at migraine onset, number of years from chronic migraine onset, T(0) Migraine Disability Assessment score, T(0) headache frequency, severity and temporal pattern (continuous vs intermittent) differed significantly between the groups.

CONCLUSIONS

Findings suggest that psychological factors can influence the clinical course of chronic migraine and that psychological evaluation with Minnesota Multiphasic Personality Inventory-2 may be a reliable approach to obtain prognostic data and information for therapy planning in patients with chronic migraine.

The differential diagnosis of chronic daily headaches: an algorithm-based approach

Chronic daily headaches (CDHs) refers to primary headaches that happen on at least 15 days per month, for 4 or more hours per day, for at least three consecutive months. The differential diagnosis of CDHs is challenging and should proceed in an orderly fashion. The approach begins with a search for "red flags" that suggest the possibility of a secondary headache. If secondary headaches that mimic CDHs are excluded, either on clinical grounds or through investigation, the next step is to classify the headaches based on the duration of attacks. If the attacks last less than 4 hours per day, a trigeminal autonomic cephalalgia (TAC) is likely. TACs include episodic and chronic cluster headache, episodic and chronic paroxysmal hemicrania, SUNCT, and hypnic headache. If the duration is > or =4 h, a CDH is likely and the differential diagnosis encompasses chronic migraine, chronic tension-type headache, new daily persistent headache and hemicrania continua. The clinical approach to diagnosing CDH is the scope of this review.

Botulinum toxin type a prophylactic treatment of episodic migraine: a randomized, double-blind, placebo-controlled exploratory study

OBJECTIVE

This exploratory trial evaluated the safety and efficacy of multiple treatments of botulinum toxin type A (BoNTA; BOTOX, Allergan, Inc., Irvine, CA, USA) as prophylactic treatment of episodic migraine headaches.

DESIGN AND METHODS

This was an 11-month randomized, double-blind, placebo-controlled, exploratory study. Patients were screened during a 30-day baseline period, and eligible patients with 4 or more migraine episodes and < or =15 headache days entered a single-blind 30-day placebo run-in period. Patients were classified as placebo nonresponders (PNR) if they had at least 4 moderate-to-severe migraine episodes and did not experience at least a 50% decrease from baseline in the frequency of migraine episodes following their placebo treatment. All other subjects were classified as placebo responders (PR). Patients were randomized within each stratum (PNR, PR) to 3 treatments with BoNTA (110 to 260 U of BoNTA per treatment cycle) or placebo at 90-day intervals using a modified follow-the-pain treatment paradigm. The primary efficacy outcome measure was the mean change from baseline in the frequency of migraine episodes for the 30 days prior to day 180 in the PNR group. Secondary efficacy measures included the proportion of patients with a decrease from baseline of 50% or more migraine episodes per 30-day period. Patients were allowed to take concomitant acute and prophylactic headache medications. Adverse events were reported.

RESULTS

A total of 809 patients were screened and 369 patients (89.2% female; mean age, 45 years; range, 20 to 65 years) entered the placebo run-in period and were subsequently randomized to BoNTA or placebo. The mean total dose of BoNTA was 190.5 units (U) (range, 110 U to 260 U). The predetermined primary efficacy endpoint was not met. Substantial mean improvements of 2.4 and 2.2 fewer migraine episodes per month at day 180 in the PNR stratum treated with BoNTA and placebo, respectively, were observed (P > .999). From day 180 through the end of the study (day 270) at least 50% of all patients in each treatment group had a decrease from baseline of 50% or more migraine episodes per 30-day period. However, in the group of patients with > or =12 headache days at baseline (and < or =15 headache days), BoNTA patients experienced a mean change from baseline of -4.0 headache episodes at day 180 compared with -1.9 headache episodes in the placebo group (P= .048). The majority of treatment-related adverse events were transient and mild to moderate in severity. Only 7 patients (1.9%) discontinued the study due to adverse events (6 BoNTA, 1 placebo).

CONCLUSION

There were no statistically significant between-group differences in the mean change from baseline in the frequency of migraine episodes per 30-day period. There were substantial, sustained improvements during the course of the study in all groups. Multiple treatments with BoNTA were shown to be safe and well tolerated over an active treatment period lasting 9 months.

Topiramate reduces headache days in chronic migraine: a randomized, double-blind, placebo-controlled study

The aim of this study was to evaluate the efficacy and tolerability of topiramate for the prevention of chronic migraine in a randomized, double-blind, placebo-controlled trial. Chronic migraine is a common form of disabling headache presenting in headache subspecialty practice. Preventive treatments are essential for chronic migraine management, although there are few or no controlled empirical trial data on their use in this patient population. Topiramate is approved for the prophylaxis of migraine headache in adults. Patients (18-65 years) who experienced chronic migraine (defined as > or =15 monthly migraine days) for > or =3 months prior to trial entry and had > or =12 migraine days during the 4-week (28-day) baseline phase were randomized to topiramate or placebo for a 16-week, double-blind trial. Topiramate was titrated (25 mg weekly) to a target dose of 100 mg/day, allowing dosing flexibility from 50 to 200 mg/day, according to patient need. Existing migraine preventive treatments, except for antiepileptic drugs, were continued throughout the trial. The primary efficacy measure was the change in number of migraine days from the 28-day baseline phase to the last 28 days of the double-blind phase in the intent-to-treat population, which consisted of all patients who received at least one dose of study medication and had one outcome assessment during the double-blind phase. Health-related quality of life was evaluated with the Migraine Specific Quality of Life Questionnaire (MSQ, Version 2.1), the Headache Impact Test (HIT-6) and the Migraine Disability Assessment (MIDAS) questionnaires, and tolerability was assessed by adverse event (AE) reports and early trial discontinuations. Eighty-two patients were screened. Thirty-two patients in the intent-to-treat population (mean age 46 years; 75% female) received topiramate (mean modal dose +/- SD = 100 +/- 17 mg/day) and 27 patients received placebo. Mean (+/-SD) baseline number of migraine days per 4 weeks was 15.5 +/- 4.6 in the topiramate group and 16.4 +/- 4.4 in the placebo group. Most patients (78%) met the definition for acute medication overuse at baseline. The mean duration of treatment was 100 and 92 days for topiramate- and placebo-treated patients, respectively. Study completion rates for topiramate- and placebo-treated patients were 75% and 52%, respectively. Topiramate significantly reduced the mean number of monthly migraine days (+/-SD) by 3.5 +/- 6.3, compared with placebo (-0.2 +/- 4.7, P < 0.05). No significant intergroup differences were found for MSQ and HIT-6. MIDAS showed improvement with the topiramate treatment group (P = 0.042 vs. placebo). Treatment emergent adverse events were reported by 75% of topiramate-treated patients (37%, placebo). The most common AEs, paraesthesia, nausea, dizziness, dyspepsia, fatigue, anorexia and disturbance in attention, were reported by 53%, 9%, 6%, 6%, 6%, 6% and 6% of topiramate-treated patients, respectively, vs. 7%, 0%, 0%, 0%, 0%, 4% and 4% of placebo-treated patients. This randomized, double-blind, placebo-controlled trial demonstrates that topiramate is effective and reasonably well tolerated when used for the preventive treatment of chronic migraine, even in the presence of medication overuse.

Greater occipital nerve injection in primary headache syndromes--prolonged effects from a single injection

Most patients with primary headache syndromes who have frequent attacks of pain have tenderness in the sub-occipital region. Injection of the greater occipital nerve (GON) with local anesthetic and corticosteroids has been widely used in clinical practice for many years, yet there is no clear understanding of its mechanisms of action. Moreover, there is no current gold-standard of practice regarding GON injections in the management of headache. We audited of our practice to generate hypotheses about the range of primary headaches that might benefit, to determine response rates to power future studies, and to assess whether we should continue to do this procedure. Twenty-six of fifty-seven injections in 54 migraineurs yielded a complete or partial response that lasted for the partial response a median of 30 days. For cluster headache 13 of 22 injections yielded a complete or partial response lasting for a median of 21 days for the partial response. Tenderness over the GON was strongly predictive of outcome, although local anesthesia after the injection was not. The presence or absence of medication overuse did not predict outcome. Apart from two patients with a small patch of alopecia the injection was well tolerated. GON injection is a useful tool in some patients that provides interim relief while other approaches are explored. It is remarkable that in all conditions in which an effect is observed the response time so much exceeds the local anesthetic effect that the mechanism of action may well be through changes in brain nociceptive pathways.

Botulinum toxin type A for the prophylactic treatment of chronic daily headache: a randomized, double-blind, placebo-controlled trial

OBJECTIVES

To identify a treatment-responsive population for botulinum toxin type A (BoNTA) and to evaluate the safety and efficacy of 3 different doses of BoNTA as prophylactic treatment of chronic daily headache (CDH).

PATIENTS AND METHODS

A randomized, double-blind, placebo-controlled study of BoNTA in patients with CDH was conducted from July 6, 2001, through November 7, 2003, at 28 North American study centers. Eligible patients were injected with BoNTA at 225 U, 150 U, 75 U, or placebo and returned for additional masked treatments at day 90 and day 180. Patients were assessed every 30 days for 9 months. The primary efficacy end point was the mean change from baseline in the frequency of headache-free days at day 180 for the placebo nonresponder group.

RESULTS

For this study, 702 patients were enrolled and randomized. The primary efficacy end point was not met. Mean improvements from baseline at day 180 of 6.0, 7.9, 7.9, and 8.0 headache-free days per month were observed in the placebo nonresponder group treated with BoNTA at 225 U, 150 U, 75 U, or placebo, respectively (P=.44). An a priori-defined analysis of headache frequency revealed that BoNTA at 225 U or 150 U had significantly greater least squares mean changes from baseline than placebo at day 240 (-8.4, -8.6, and -6.4, respectively; P=.03 analysis of covariance). Only 27 of 702 patients (3.8%) withdrew from the study because of adverse events, which generally were transient and mild to moderate.

CONCLUSIONS

Although the primary efficacy end point was not met, all groups responded to treatment. The 225 U and 150 U groups experienced a greater decrease in headache frequency than the placebo group at day 240. The placebo response was higher than expected. BoNTA was safe and well tolerated. Further study of BoNTA prophylactic treatment of CDH appears warranted.

The clinical characteristics of headache in patients with pituitary tumours

The clinical characteristics of 84 patients with pituitary tumour who had troublesome headache were investigated. The patients presented with chronic (46%) and episodic (30%) migraine, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT; 5%), cluster headache (4%), hemicrania continua (1%) and primary stabbing headache (27%). It was not possible to classify the headache according to International Headache Society diagnostic criteria in six cases (7%). Cavernous sinus invasion was present in the minority of presentations (21%), but was present in two of three patients with cluster headache. SUNCT-like headache was only seen in patients with acromegaly and prolactinoma. Hypophysectomy improved headache in 49% and exacerbated headache in 15% of cases. Somatostatin analogues improved acromegaly-associated headache in 64% of cases, although rebound headache was described in three patients. Dopamine agonists improved headache in 25% and exacerbated headache in 21% of cases. In certain cases, severe exacerbations in headache were observed with dopamine agonists. Headache appears to be a significant problem in pituitary disease and is associated with a range of headache phenotypes. The presenting phenotype is likely to be governed by a combination of factors, including tumour activity, relationship to the cavernous sinus and patient predisposition to headache. A proposed modification of the current classification of pituitary-associated headache is given.

Botulinum Toxin Type A (BOTOX ® ) for the Prophylactic Treatment of Chronic Daily Headache: A Randomized, Double‐Blind, Placebo‐Controlled Trial

OBJECTIVE

The objective of this study was to evaluate the safety and efficacy of botulinum toxin type A (BoNT-A; BOTOX, Allergan, Inc.) for the prophylactic treatment of chronic daily headache (CDH).

BACKGROUND

Several open-label and small controlled trials suggest that BoNT-A may be effective in the prophylactic treatment of headache.

DESIGN AND METHODS

This was an 11-month, randomized double-blind, placebo-controlled study of BoNT-A for the treatment of patients aged 18 to 65 years old with 16 or more headache days per 30 days conducted at 13 North American study centers. Following a 30-day screening period and a 30-day, single-blind, placebo-response period to identify placebo responders, eligible patients from both the placebo responder and placebo nonresponder groups were injected with BoNT-A or placebo every 90 days and assessed every 30 days for 9 months, a period encompassing three treatment cycles. The primary efficacy measure was the change from baseline in the frequency of headache-free days in a 30-day period for the placebo nonresponder group at day 180, the chosen efficacy time point. The secondary efficacy measure was the proportion of patients with a decrease from baseline of 50% or more in the frequency of headache days per 30-day period for the placebo nonresponder group at day 180. The change from baseline in the frequency of headaches (per 30-day period), the proportion of patients with a decrease from baseline of 50% or greater in the frequency of headaches per 30-day period, acute medication use, and adverse events were also assessed.

RESULTS

Of 571 patients assessed over the baseline period, 355 (mean age, 43.5 years; 300/355 [84.5%] female) were enrolled and randomized. At the end of the placebo run-in period, 279 patients (79%) were classified as placebo nonresponders and 76 patients (21%) as placebo responders. Subsequently, patients were randomized within each group to receive either BoNT-A or placebo. In the placebo nonresponder stratum, the mean number of headache-free days at baseline was 5.8 (+/-4.7) for BoNT-A- versus 5.5 (+/-4.7) for placebo-treated patients. At day 180, placebo nonresponders treated with BoNT-A had an improved mean change from baseline of 6.7 headache-free days per 30-day period compared to a mean change from baseline of 5.2 headache-free days for placebo-treated patients. The between-group difference of 1.5 headache-free days favored BoNT-A treatment, although the difference between the groups was not statistically significant. However, a statistically significant difference was observed at day 180 endpoint for the secondary efficacy measure. A significantly higher percentage of BoNT-A patients had a decrease from baseline of 50% or greater in the frequency of headache days per 30-day period at day 180 (32.7% vs. 15.0%, P=.027). Also, the mean change from baseline in the frequency of headaches per 30-day period at day 180 was -6.1 for BoNT-A patients vs. -3.1 for the placebo patients (P=.013). Only 4 of 173 BoNT-A patients (2.3%) discontinued the study due to adverse events. The majority of treatment-related adverse events were transient and mild to moderate in severity.

CONCLUSIONS

BoNT-A treatment resulted in patients having, on average, approximately seven more (1 week) headache-free days compared to baseline. Although at the primary time point (day 180) the BoNT-A treatment resulted in a 1.5 between-group difference compared to placebo, this difference was not statistically significant. The treatment met secondary efficacy outcome measures, including the percentage of patients experiencing a 50% or more decrease in the frequency of headache days, in addition to statistically significant reductions in headache frequency. BoNT-A was also well tolerated in patients with CDH.

Management of trigeminal autonomic cephalgias and hemicrania continua

The trigeminal autonomic cephalgias (TACs) are a group of primary headache disorders characterised by unilateral trigeminal distribution pain that occurs in association with ipsilateral cranial autonomic features. This group of headache disorders includes cluster headache, paroxysmal hemicrania and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT syndrome). Although hemicrania continua has previously been classified amongst the TACs, its nosological status remains unclear. Despite their similarities, these disorders differ in their clinical manifestations and response to therapy, thus underpinning the importance of recognising them. We have outlined the clinical manifestations, differential diagnoses, diagnostic workup and the treatment options for each of these syndromes.

Migraine: diagnosis and management

Migraine is the most common form of disabling primary headache and affects approximately 12% of studied Caucasian populations. Non-pharmacological management of migraine largely consists of lifestyle advice to help sufferers avoid situations in which attacks will be triggered. Preventive treatments for migraine should usually be considered on the basis of attack frequency, particularly its trend to change with time, and tract-ability to acute care. Acute care treatments for migraine can be divided into non-specific treatments (general analgesics, such as aspirin or non-steroidal anti--inflammatory drugs) and treatments relatively specific to migraine (ergotamine and the triptans). The triptans--sumatriptan, naratriptan, rizatriptan, zolmitriptan, almotriptan, eletriptan and frovatriptan--are potent serotonin, 5-HT1B/1D, receptor agonists which represent a major advance in the treatment of acute migraine. Chronic daily headache in association with analgesic overuse is probably the major avoidable cause of headache disability in the developed world.

Does chronic daily headache arise de novo in association with regular use of analgesics?

BACKGROUND

The prevalence of chronic daily headache in association with regular use of analgesics is about 2%. Whether regular use of analgesics has a causal or consequential relationship to daily headache has not been established. A causal relationship has been suggested consequent to the observation of improvement or resolution of headache following analgesic withdrawal in patients attending headache clinics, but this observation has not been validated by controlled trials.

PURPOSE

The aim of our investigation was to determine whether regular use of analgesics is associated with the development of chronic daily headache de novo and to characterize the clinical phenotype of those headaches by carefully studying chronic daily headache in patients with regular use of analgesics for a nonheadache indication.

METHODS

Patients attending a rheumatology-monitoring clinic of second-line agents were interviewed by a training neurologist with regard to their analgesic and headache history. Headache classification was according to the criteria of the International Headache Society. Daily headache characteristics were surveyed via a standardized questionnaire, and headache features were further explored by a trained medical interviewer.

RESULTS

Of 110 patients presenting to a rheumatology-monitoring clinic, 73% had a diagnosis of rheumatoid arthritis, 23% had seronegative arthritis, and 4% comprised a miscellaneous group. One hundred three were using one or more analgesics regularly for their arthritis. Of this group, 8 (7.6%) reported a history of chronic daily headache, each of whom reported a history of migraine. The onset of migraine occurred before the onset of chronic daily headache in 7 patients and at about the same time as the chronic daily headache in 1 patient. In those with onset of migraine prior to chronic daily headache, the mean interval before the onset of headache was 30 years (range, 10 to 50 years). Regular use of analgesics preceded the onset of daily headache in 5 patients by a mean of 5.4 years (range, 2 to 10 years). In 1 patient, analgesic use and the development of daily headache occurred at about the same time. In 1 patient, the onset of daily headache preceded regular use of analgesics by almost 30 years. Five of those with regular use of analgesics had been taking an opiate-based preparation in combination with a nonsteroidal anti-inflammatory agent in 4. Two had been on a combination of acetaminophen (paracetamol) and a nonsteroidal anti-inflammatory drug. The minimum number of tablets per week was 7, and the mean was 48 (range, 7 to 87). Of those patients who did not have daily headache, 41% had a history of migraine and 27% reported a history of tension-type headache.

CONCLUSION

These findings suggest that individuals with primary headache, specifically migraine, are predisposed to developing chronic daily headache in association with regular use of analgesics.

Opioid resistance in chronic daily headache: a synthesis of ideas from the bench and bedside

Chronic daily headache is a complex pain disorder that encompasses many diagnostic and therapeutic challenges. Our understanding of the pathophysiologic processes of intermittent migraine has improved over the past decade, but the biologic basis of chronic daily headache remains obscure. Some of the more common issues confounding management of patients who experience chronic daily headache are medication overuse, psychiatric comorbidity, refractoriness to pharmacologic treatments, and disability. Long-acting opioid analgesics would appear to provide a viable treatment option for those patients who remain refractory to other treatment interventions; however, clinical experience often does not support this belief. Current concepts of the pathophysiologic basis of chronic pain and associated neural plasticity may elucidate a biologic basis for the general inefficacy of opioids in the management of chronic daily headache. This article explores the models of pathophysiology for migraine and chronic daily headache, the concept of chronic daily headache as a neuropathic pain syndrome, neural plasticity in the context of neuropathic pain states, the physiologic basis for opioid tolerance and opioid-induced hyperalgesia, and how each of these conditions interact to provoke the general lack of opioid efficacy often observed in the management of chronic daily headache.