Pathophysiology of migraine headache

Spatiotemporally varying visual hallucinations: II. Spectral classification and comparison with theory

In order to better understand the nature of visual hallucinations, and to test predictions of spatiotemporally oscillating hallucinations from a recent corticothalamic model of visual dynamics, clinical descriptions of hallucinations are used to establish boundaries on the spatiotemporal frequencies observed in various disorders. Detailed comparisons with hallucinations during migraine aura demonstrate that key features are consistent with corticothalamic origin and specific abnormalities, but underline the need for more detailed quantitative data to be obtained on temporally oscillating hallucinations more generally.

Neuro-ophthalmologic manifestations of primary headache disorders

Headaches are the most common disorders of the central nervous system affecting 46% of the adult population worldwide. Headaches may be lifelong illnesses, often associated with substantial disability for the individual and the population as a whole. The International Classification of Headache Disorders (ICHD-II) codifies headache disorders into fourteen categories, predominantly primary headaches and secondary headache disorders. Primary headache disorders, mainly migraine and trigeminal autonomic cephalgias (TACs), are frequently associated with neuro-ophthalmologic manifestations. Ophthalmologists are often the first physicians to be involved in the deciphering of headache-related visual disturbances. This article reviews two major primary headache disorders, migraine and trigeminal autonomic cephalgias, and discusses their neuro-ophthalmic complications, clinical presentation, and treatment.

1 Hz rTMS enhances extrastriate cortex activity in migraine: Evidence of a reduced inhibition?

We recently reported a paradoxical facilitatory effect of 1 Hz repetitive TMS (rTMS) on the primary visual cortex in migraine possibly due to the failure of inhibitory circuits, unable to be upregulated by low frequency rTMS. To investigate if inhibitory circuit dysfunction extends beyond striate cortex in migraine with aura, we studied the effects of 1 Hz rTMS over the right extrastriate cortex on perception of illusory contours in these patients. Low-frequency rTMS enhanced activity of extrastriate cortex in migraineurs, speeding up reaction times on illusory contour perception. This finding supports the view of a failure of inhibitory circuits also involving the extrastriate cortex in migraine with aura.

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.

Do over-the-counter medications for migraine hinder the physician?

The availability of many over-the-counter drugs that were formerly prescription medications enable patients with migraine to self-medicate easily and delay entry into the appropriate medical management. The potential for adverse effects, drug interactions, and analgesic rebound headaches can often be complications that hinder treatment. Over-the-counter products force the patient to employ a less effective step-care approach as opposed to evidence-based guidelines.