Citations

Significant progress in molecular genetics has advanced our understanding of the genetic basis of migraine. The fundamentals of molecular genetics, and the recent advances in the field, are important for clinicians to understand, as they provide a foundation for critical appraisal of the literature, unprecedented insights into the pathogenesis of the disorder, and reveal promising treatment targets for future drug development. This paper provides a primer of molecular genetics and will be followed by a companion paper on the genetic advances in migraine, the methodology of genome wide association studies, and the potential clinical implications.

Objective Preclinical evaluation of headache by behavioral assessment of reward from pain relief. Methods Inflammatory mediators (IMs) or control solution were applied to the rat dura mater to elicit a presumed state of cephalic pain. Hind paw incision was used in separate groups of animals to model noncephalic postsurgical pain. Drugs were given systemically or microinjected within the rostral ventromedial medulla (RVM), nucleus accumbens (NAc), or rostral anterior cingulate cortex (rACC). Peripheral nerve block was produced at the level of the popliteal fossa, and behavior was assessed using evoked sensory stimuli or conditioned place preference (CPP). Immunohistochemistry and brain microdialysis measurements were performed. Results Dural IMs produced long‐lasting generalized cutaneous allodynia. RVM lidocaine produced CPP, increased NAc c‐Fos, and dopamine release selectively in rats receiving dural IMs; CPP was blocked by intra‐NAc α‐flupenthixol, a dopaminergic antagonist. Intravenous α‐calcitonin gene‐related peptide (αCGRP) (8–37) produced CPP and elicited NAc dopamine release selectively in rats treated with dural IMs. Prior lesion of the rACC or treatment with systemic sumatriptan or αCGRP (8–37) abolished RVM lidocaine‐induced CPP in IM‐treated rats. Sumatriptan treatment blocked NAc dopamine release in IM‐treated rats receiving RVM lidocaine. Systemic sumatriptan did not alter pain relief‐induced CPP in rats with incisional injury. Interpretation Cephalic pain was unmasked in rats by assessment of motivated behavior to seek relief. Relief of pain activates the dopaminergic reward pathway to elicit negative reinforcement of behavior. Medications clinically effective for migraine headache selectively elicit relief of ongoing cephalic, but not postsurgical, noncephalic pain. These studies provide a platform for exploring migraine pathophysiology and for the discovery of new headache therapies. Ann Neurol 2013;74:257–265

Reversible cerebral vasoconstriction syndrome ( RCVS ) is a cerebrovascular disorder with a clinical picture that continues to be refined. It has presented to multiple subspecialties over the past several decades, bringing with it many questions regarding risk factors, diagnosis, and management. Answers have been forthcoming but many questions remain. RCVS presents with recurrent, secondary thunderclap headaches and predominantly affects young women. The mechanism of vasoconstriction is unclear, but there has been speculation regarding a hyperadrenergic state. Diagnosis requires physician awareness, vascular imaging, and knowledge of the differential. The hallmark of its diagnosis is reversibility. Management is empiric, usually with calcium‐channel blockers, as there are no controlled treatment trials for RCVS . Randomized controlled trials are needed.

Objective To describe a standardized methodology for the performance of peripheral nerve blocks ( PNB s) in the treatment of headache disorders. Background PNBs have long been employed in the management of headache disorders, but a wide variety of techniques are utilized in literature reports and clinical practice. Methods The A merican H eadache S ociety S pecial I nterest S ection for PNBs and other I nterventional P rocedures convened meetings during 2010‐2011 featuring formal discussions and agreements about the procedural details for occipital and trigeminal PNBs . A subcommittee then generated a narrative review detailing the methodology. Results PNB indications may include select primary headache disorders, secondary headache disorders, and cranial neuralgias. Special procedural considerations may be necessary in certain patient populations, including pregnancy, the elderly, anesthetic allergy, prior vasovagal attacks, an open skull defect, antiplatelet/anticoagulant use, and cosmetic concerns. PNBs described include greater occipital, lesser occipital, supratrochlear, supraorbital, and auriculotemporal injections. Technical success of the PNB should result in cutaneous anesthesia. Targeted clinical outcomes depend on the indication, and include relief of an acute headache attack, terminating a headache cycle, and transitioning out of a medication‐overuse pattern. Reinjection frequency is variable, depending on the indications and agents used, and the addition of corticosteroids may be most appropriate when treating cluster headache. Conclusions These recommendations from the A merican H eadache S ociety S pecial I nterest S ection for PNBs and other I nterventional P rocedures members for PNB methodology in headache disorder treatment are derived from the available literature and expert consensus. With the exception of cluster headache, there is a paucity of evidence, and further research may result in the revision of these recommendations to improve the outcome and safety of these interventions.

Concussion awareness and management in sports have gained a great deal of attention in light of research illustrating the potentially devastating consequences of repeated traumatic brain injuries. In order to address this public health crisis, numerous states have passed legislation that mandates medical clearance before being eligible to return to play of concussed athletes by a qualified healthcare provider. As the number of qualified healthcare providers with expertise in the diagnosis and management of concussions remains very small, patient safety and the ability to fulfill these legislative return-to-play requirements present unique problems to rural communities without easy access to subspecialty care. Telemedicine is a possible means by which to address the needs of the rural student-athlete.