Current status of genetic discoveries in migraine: familial hemiplegic migraine and beyond

Spectrum of migraine variants and beyond: The individual syndromes in children

"Migraine-related conditions" are probably the second most common condition after seizure encountered in pediatric neurology requiring frequent Emergency Department visits. Among migraines, migraine-related condition presents with an acute onset sign or symptom other than headache or visual aura of unknown etiology. A delay in diagnosis is a common occurrence. Previously, the authors proposed a common clinical profile and suggested that the future review should seek the applicability of the common profile in aid to clinical diagnosis of migraine-related individual syndromes. Authors describe the clinical characteristics and differential diagnosis of the spectrum of migraine variants and beyond in children.

Relief from migraine headache with aripiprazole treatment

There have been many reports of the association between migraine headaches and psychiatric disorders as well as of the utility of dopamine antagonists in the treatment of migraine headache. There is increasing evidence to support the activation of dopaminergic systems as a primary component of migraine pathogenesis. This report documents 3 cases of female migraineurs who received the dopamine modulator aripiprazole for treatment of co-occurring psychiatric disorders and experienced a decrease in migraine frequency and severity. A hypothesis as to the mechanism of action of dopamine regulation in migraine treatment is discussed.

Effects of pyrethroids on voltage-sensitive calcium channels: a critical evaluation of strengths, weaknesses, data needs, and relationship to assessment of cumulative neurotoxicity

The Food Quality Protection Act of 1996 requires that the U.S. Environmental Protection Agency conduct cumulative risk assessments for classes of pesticides that have a common mode or mechanism of action. For the pyrethroid insecticides, disruption of voltage-sensitive sodium channel function is generally accepted as the mechanism underlying acute neurotoxicity. However, data exist which suggest that voltage-sensitive calcium (Ca(2+)) channels (VSCC) may also be important targets of pyrethroid action. VSCC are important to neuronal function during development and for neurotransmitter release, gene expression, and electrical excitability in the nervous system. Disruption of these and other processes mediated by VSCC can result in neurotoxicity. If effects on VSCC are demonstrated to contribute to pyrethroid neurotoxicity, then such effects will have to be considered when making decisions regarding cumulative risk of exposure to this class of compounds. This document provides a critical review of the data related to the hypothesis that VSCC are important targets of pyrethroid effects. Data supporting effects of pyrethroids on VSCC have been generated by several different laboratories using different techniques and biological preparations. Thus, the many reports of effects on VSCC provide evidence that pyrethroids may interact with VSCC. However, evidence to support a role of VSCC in pyrethroid neurotoxicity is based entirely on in vitro observations, and numerous limitations exist in these data, including: (1) lack of defined concentration-response relationships, with some effects observed only at relatively high concentrations, (2) the use of indirect measures of VSCC function, (3) data from nonmammalian species, (4) data from studies that have not been peer-reviewed, (5) the need for replication of some effects, and (6) inconsistent or contradictory results from different laboratories/preparations. Thus, at the present time, it is premature to conclude that effects on VSCC play an important role in the acute neurotoxicity of pyrethroid insecticides in mammals. To demonstrate that VSCC are important targets of pyrethroid neurotoxicity in mammals, in vivo studies supporting a role for pyrethroid effects on VSCC are needed. Additional support could be provided by demonstration of direct effects of pyrethroid compounds on mammalian neuronal VSCC in vitro, including demonstration that concentration-response relationships are similar, or greater, in sensitivity to effects of pyrethroids on voltage-sensitive sodium channels. If such effects were to be demonstrated, the rationale for considering VSCC as targets of pyrethroid compounds when assessing cumulative risk would be strengthened. However, at the present time, the data available neither support nor refute conclusively the hypothesis that effects on VSCC are important to the acute neurotoxicity of pyrethroids.

The clinical spectrum of migraine

The wide clinical spectrum of migraine frequently challenges the physician's diagnostic acumen. A structured approach to the patient and a better comprehension of this variability of presentation, should translate into better quality of care for migraineurs.

Serial MRI in a case of familial hemiplegic migraine

We report MRI findings in a patient with familial hemiplegic migraine (FHM) with repeated episodes of hemiparesis. FHM is caused by a penetrant autosomal dominant genetic mutation; several mutations have been genotyped, involving brain-expressed ion channels. We found cerebral oedema, dilatation of intracerebral vessels and decreased water diffusion contralateral to the hemiparesis, not respecting vascular territories, with subsequent complete resolution of both clinical and imaging abnormalities. These results are thought to be consistent with an underlying primary neuronal pathology with secondary vascular effects, as opposed to the traditional, primarily vascular, model of migraine aetiology.

Comparison of visual and auditory evoked cortical potentials in migraine patients between attacks

OBJECTIVE

As both habituation of pattern reversal visual evoked potentials (PR-VEP) (Schoenen J, Wang W, Albert A, Delwaide PJ. Potentiation instead of habituation characterizes visual evoked potentials in migraine patients between attacks. Eur J Neurol 1995;2:115-122) and intensity dependence of auditory evoked cortical potentials (IDAP) (Wang W, Timsit-Berthier M, Schoenen J. Intensity dependence of auditory evoked potentials in migraine: an indication of cortical potentiation and low serotonergic neurotransmission? Neurology 1996;46:1404-1409) were found abnormal in migraine between attacks, we have searched for intraindividual correlations between both tests in 59 migraine patients (22 with aura [MA], 37 without aura [MO]) and in 23 healthy volunteers (HV).

METHODS

Amplitude change of the PR-VEP N1-P1 was measured between the 1st and 5th block of 50 sequential averagings during continuous stimulation at 3.1 Hz. IDAP was computed from N1-P2 amplitudes of 100 averagings during stimulations at 40, 50, 60 and 70 dB SL. Amplitude-stimulus intensity function (ASF) slopes and amplitude changes between 40 and 70 dB were calculated. MO and MA differed from HV in PR-VEP amplitude change (P=0.007) and IDAP slope (P = 0.0004).

RESULTS

There was no significant correlation between VEP amplitude changes and IDAP slopes, nor between the latter two and attack frequency or disease duration. A negative correlation was found between the amplitude of the first block of averaged responses and potentiation of VEP in all subject groups (P = 0.03) as well as between the amplitude of the auditory evoked potential, at 40 dB, and the percentage of amplitude increase between 40 and 70 dB in MO (P = 0.004) and MA (P = 0.007). ASF slopes and 40 dB amplitudes were significantly correlated only in the MA group (P = 0.002). These results confirm the interictal deficit of habituation in cortical processing of repetitive visual and auditory information in migraine. Since there is no intraindividual correlation between the cortical responses to these sensory modalities they are complementary tools for the study of migraine and may help to identify subgroups of patients with distinct pathophysiological mechanisms.

CONCLUSIONS

The strong negative correlation between the initial amplitude of evoked potentials and their amplitude increase during subsequent averaging confirms that the response potentiation in migraine is likely to be due to a reduced preactivation level of sensory cortices.