Increased susceptibility to cortical spreading depression in an animal model of medication-overuse headache

Medication-overuse headache: a perspective review

Medication-overuse headache (MOH) is a debilitating condition in which frequent and prolonged use of medication for the acute treatment of pain results in the worsening of the headache. The purpose of this paper is to review the most recent literature on MOH and discuss future avenues for research. MOH accounts for a substantial share of the global burden of disease. Prevalence is often reported as 1-2% but can be as high as 7% overall, with higher proportions among women and in those with a low socioeconomic position. Management consists of withdrawing pain medication, focusing on prophylactic and nonmedical treatments, and limiting acute symptomatic medication. Stress reduction and lifestyle interventions may support the change towards rational pain medication use. Support, follow up, and education are needed to help patients through the detoxification period. There is fertile ground for research in MOH epidemiology, pathophysiology, and neuroimaging. Randomized and long-term follow-up studies on MOH treatment protocols are needed. Further focused research could be of major importance for global health.

Pain modulation is affected differently in medication-overuse headache and chronic myofascial pain - A multimodal MRI study

Background Neuroimaging studies revealed structural and functional changes in medication-overuse headache (MOH), but it remains unclear whether similar changes could be observed in other chronic pain disorders. Methods In this cross-sectional study, we investigated functional connectivity (FC) with resting-state functional magnetic resonance imaging (fMRI) and white matter integrity using diffusion tensor imaging (DTI) to measure fractional anisotropy (FA) and mean diffusivity (MD) in patients with MOH ( N = 12) relative to two control groups: patients with chronic myofascial pain (MYO; N = 11) and healthy controls (CN; N = 16). Results In a data-driven approach we found hypoconnectivity in the fronto-parietal attention network in both pain groups relative to CN (i.e. MOH < CN and MYO < CN). In contrast, hyperconnectivity in the saliency network (SN) was detected only in MOH, which correlated with FA in the insula. In a seed-based analysis we investigated FC between the periaqueductal grey (PAG) and all other brain regions. In addition to overlapping hyperconnectivity seen in patient groups (relative to CN), MOH had a distinct connectivity pattern with lower FC to parieto-occipital regions and higher FC to orbitofrontal regions compared to controls. FA and MD abnormalities were mostly observed in MOH, involving the insula. Conclusions Hyperconnectivity within the SN along with associated white matter changes therein suggest a particular role of this network in MOH. In addition, abnormal connectivity between the PAG and other pain modulatory (frontal) regions in MOH are consistent with dysfunctional central pain control.

Activation of dura-sensitive trigeminal neurons and increased c-Fos protein induced by morphine withdrawal in the rostral ventromedial medulla

Aims

Overuse of medications used to treat migraine headache can increase the frequency of headaches. Sudden abstinence from migraine medication can also lead to a period of withdrawal-induced headaches. The aim of this study was to examine the effect of morphine withdrawal localized to the rostral ventromedial medulla (RVM) on the activity of dura-sensitive spinal trigeminal nucleus caudalis (Vc) neurons.

Methods

Rats were implanted with either morphine or placebo pellets for six to seven days before the microinjection of naloxone methiodide or phosphate-buffered saline into the RVM in urethane-anesthetized animals. Dura-sensitive neurons were recorded in the Vc and the production of c-Fos-like immunoreactivity was quantified.

Results

In chronic morphine-treated animals, naloxone methiodide microinjections produced a significant increase both in ongoing and facial heat-evoked activity and an increase in Fos-positive neurons in the Vc and in the nucleus reticularis dorsalis, a brainstem region involved in diffuse noxious inhibitory controls.

Conclusions

These results indicate that activation of pronociceptive neurons in the RVM under conditions of morphine withdrawal can increase the activity of neurons that transmit headache pain. Modulation of the subnucleus reticularis dorsalis by the RVM may explain the attenuation of conditioned pain modulation in patients with chronic headache.

Triptans disrupt brain networks and promote stress-induced CSD-like responses in cortical and subcortical areas

A number of drugs, including triptans, promote migraine chronification in susceptible individuals. In rats, a period of triptan administration over 7 days can produce "latent sensitization" (14 days after discontinuation of drug) demonstrated as enhanced sensitivity to presumed migraine triggers such as environmental stress and lowered threshold for electrically induced cortical spreading depression (CSD). Here we have used fMRI to evaluate the early changes in brain networks at day 7 of sumatriptan administration that may induce latent sensitization as well as the potential response to stress. After continuous infusion of sumatriptan, rats were scanned to measure changes in resting state networks and the response to bright light environmental stress. Rats receiving sumatriptan, but not saline infusion, showed significant differences in default mode, autonomic, basal ganglia, salience, and sensorimotor networks. Bright light stress produced CSD-like responses in sumatriptan-treated but not control rats. Our data show the first brain-related changes in a rat model of medication overuse headache and suggest that this approach could be used to evaluate the multiple brain networks involved that may promote this condition.

Treatment of medication-overuse headache: A systematic review

INTRODUCTION

The objective of this review is to provide an evidence-based discussion of different treatment strategies for medication-overuse headache (MOH).

METHOD

We searched PubMed for articles discussing the treatment and prognosis of MOH published between 2004 and August 2014. Titles, abstract and articles were reviewed systematically. The level of evidence provided by each study of the included articles was determined according to the American Academy of Neurology Clinical practice guideline manual. We discuss the level of evidence to support the early discontinuation/withdrawal of overused medications, the level of evidence to support the use of preventive treatment, the short- and long-term prognosis, and the outcome according to the class of drug overused in patients diagnosed with MOH.

RESULTS

The initial search resulted in 1313 articles; 68 articles met our inclusion criteria and were discussed. The level of evidence to support early discontinuation of overused medications alone is low due to the absence of controlled studies. Adding preventive medication to early discontinuation led to a better outcome than early discontinuation alone. For patients with chronic migraine (CM) and medication overuse (MO), there are large randomized control trials supporting the use of onabotulinumtoxinA and topiramate without early discontinuation of overuse; however, the evidence is limited since data were obtained from post hoc analysis.

CONCLUSION

Considering current available evidence and the systemic toxicity of overusing acute headache medication, we suggest discontinuation of the overused medication with the addition of preventive medication. Appropriately sized, randomized controlled trials evaluating the safety and long-term efficacy of preventive medication plus early discontinuation of overuse vs preventive medication alone vs early discontinuation of overuse alone are needed.