Assessment of Excitability at the Brainstem and Cortex in Primary Headaches With Allodynia

Neurophysiological and Clinical Outcomes in Episodic Migraine Without Aura: A Cross-Sectional Study

PURPOSE

The aim of this study was to assess differences between people with episodic migraine and healthy controls in some neurophysiological and clinical outcomes, which, in turn, may highlight the differences in sensory processing, especially in cortical excitability, pain processing, and executive function.

METHODS

A cross-sectional study was performed, including the following outcomes: pressure pain thresholds with algometry; resting motor threshold, short-interval intracortical inhibition, and intracortical facilitation with transcranial magnetic stimulation; and executive functions with the trail making test and the frontal assessment battery.

RESULTS

Thirty adults with migraine (36 ± 10 years) and 30 healthy controls (29 ± 14 years) were included in this study. Compared with the healthy controls, participants with migraine presented lower pressure pain thresholds values in all the assessed muscles ( P < 0.001), lower resting motor threshold (-10.5% of the stimulator output, 95% CI: -16.8 to -4.2, P = 0.001, Cohen d = 0.869) and higher short-interval intracortical inhibition motor-evoked potential's amplitude at 3 ms (0.25, 95% CI: 0.05 to 0.46, P = 0.015, Cohen d = 0.662), and worse performances both in trail making test (7.1, 95% CI: 0.9 to 13.4, P = 0.027, Cohen d = 0.594) and frontal assessment battery (-1.1, 95% CI: -1.7 to -0.5, P = 0.001, Cohen d = 0.915).

CONCLUSIONS

Participants with migraine presented significant differences in cortical excitability, executive functions, and pressure pain thresholds, compared with healthy controls.

Clinical diagnostic utility of transcranial magnetic stimulation in neurological disorders. Updated report of an IFCN committee

The review provides a comprehensive update (previous report: Chen R, Cros D, Curra A, Di Lazzaro V, Lefaucheur JP, Magistris MR, et al. The clinical diagnostic utility of transcranial magnetic stimulation: report of an IFCN committee. Clin Neurophysiol 2008;119(3):504-32) on clinical diagnostic utility of transcranial magnetic stimulation (TMS) in neurological diseases. Most TMS measures rely on stimulation of motor cortex and recording of motor evoked potentials. Paired-pulse TMS techniques, incorporating conventional amplitude-based and threshold tracking, have established clinical utility in neurodegenerative, movement, episodic (epilepsy, migraines), chronic pain and functional diseases. Cortical hyperexcitability has emerged as a diagnostic aid in amyotrophic lateral sclerosis. Single-pulse TMS measures are of utility in stroke, and myelopathy even in the absence of radiological changes. Short-latency afferent inhibition, related to central cholinergic transmission, is reduced in Alzheimer's disease. The triple stimulation technique (TST) may enhance diagnostic utility of conventional TMS measures to detect upper motor neuron involvement. The recording of motor evoked potentials can be used to perform functional mapping of the motor cortex or in preoperative assessment of eloquent brain regions before surgical resection of brain tumors. TMS exhibits utility in assessing lumbosacral/cervical nerve root function, especially in demyelinating neuropathies, and may be of utility in localizing the site of facial nerve palsies. TMS measures also have high sensitivity in detecting subclinical corticospinal lesions in multiple sclerosis. Abnormalities in central motor conduction time or TST correlate with motor impairment and disability in MS. Cerebellar stimulation may detect lesions in the cerebellum or cerebello-dentato-thalamo-motor cortical pathways. Combining TMS with electroencephalography, provides a novel method to measure parameters altered in neurological disorders, including cortical excitability, effective connectivity, and response complexity.

The impact of external trigeminal nerve stimulator (e-TNS) on prevention and acute treatment of episodic and chronic migraine: A systematic review

OBJECTIVE

The aim of this systematic review was to analyze the effectiveness and safety of the external trigeminal nerve stimulator (eTNS) for the prevention and acute treatment of migraine attacks in episodic and chronic migraine patients.

METHODS

We have conducted a systematic literature search in four databases that yielded 433 citations and additional seven citations were found via hand-search. Two randomised placebo-controlled trials and five prospective case series were included in the analysis.

RESULTS

Concerning prevention, statistically significant differences were found with respect to reduction of migraine attacks (0.67 less migraine attacks per month), migraine days (1.74 less migraine days per month), headache days (2.28 less headache days per month), and acute antimigraine drug intake (4.24 less instances of acute drug intake per month). Concerning acute treatment, statistically significant differences were found with respect to pain reduction on a visual analogue scale at 1/2/24 h post-acute treatment (1.68/1.02/1.08 improvement, respectively). No serious adverse events occurred in any of the studies.

CONCLUSIONS

While e-TNS has the potential to improve migraine symptoms, for its establishment in the standard practice, high quality comparative data, studies with larger sample sizes, and studies with standard and relevant primary outcome parameters are needed.

Trigeminal Hyperexcitability in Idiopathic Intracranial Hypertension: A Blink Reflex Study

PURPOSE

To compare blink reflex examination findings in patients with idiopathic intracranial hypertension (IIH) with migraineurs and controls and to investigate the role of blink reflex data in the follow-up by evaluating their relationship with clinical symptoms.

METHODS

We included 23 patients with IIH, 15 migraineurs, and 16 controls. Blink reflex was studied with bilateral paired stimulations, and the 2R2/1R2 and 2R2c/1R2c area ratios, 1R2, 2R2, 1R2c, and 2R2c latencies were compared (R2:ipsilateral R2 response, R2c:contralateral R2 response).

RESULTS

2R2/1R2 area ratios at 200, 300, and 500 ms interstimulus intervals were significantly higher in the IIH group compared with the controls, and significantly higher 2R2/1R2 area ratio at 200 ms interstimulus interval was also detected in the IIH group compared with the migraine group. Significantly shorter 2R2 latencies were found at 500 and 800 ms interstimulus intervals in IIH group compared with the migraine group and controls. Significantly higher 2R2/1R2 area ratios at 500, 800 ms, and 2R2c/1R2c area ratios at 300, 500, and 800 ms were detected in patients with IIH in remission compared with patients with attacks.

CONCLUSIONS

The significant increase in R2 recovery rates in patients with IIH in remission suggests that there is an increased excitability in the trigeminal pathways. Our findings may provide a new perspective for IIH mechanism related to trigeminal hyperexcitability and evaluating new management strategies.

Identification of Allodynic Migraine Patients with the Turkish Version of the Allodynia Symptom Checklist: Reliability and Consistency Study

INTRODUCTION

Cutaneous allodynia is regarded as an expression of central sensitization in migraine. Although the gold standard is quantitative sensory testing, several practical assessment questionnaires have been developed to assess allodynia in migraine. We aimed to establish the first valid Turkish allodynia assessment questionnaire based on a 12-item allodynia symptom checklist and to evaluate the associated factors.

METHODS

The first part of the study included the translation and cultural adaptation of a Turkish version of the checklist. The Turkish version of the questionnaire was administered to 344 episodic and chronic migraine patients, who were chosen according to the International Classification of Headache Disorders -III beta criteria.

RESULTS

The total checklist score showed excellent test-retest reliability (r=0.821). The internal consistency of the checklist was assessed using Cronbach alpha values and was found to be acceptable (Cronbach alpha for the checklist=0.767). Data analysis revealed that 10 items of the questionnaire adequately identified allodynic subjects. Cutaneous allodynia was present in 218 (63.4%) migraine patients. Allodynia was more prominent in patients experiencing migraine with aura (p=0.008) and in females (p<0.001). Multiple logistic regression analysis found that female gender, aura existence, longer headache duration, and higher attack frequency were the major determinants of cutaneous allodynia.

CONCLUSION

Allodynia is common and has clinical significance in migraine; therefore, establishing a validated Turkish questionnaire for the assessment of allodynia was necessary. In this study, a Turkish version of the allodynia symptom checklist was validated and found to be convenient for the identification of allodynia in migraine patients.

Characterization of Migraineurs Having Allodynia: Results of a Large Population-based Study

OBJECTIVE

Allodynia reflects the clinical correlate of central sensitization, but it is usually neglected in clinical headache management. We aimed to report the prevalence and previously unnoticed associations of allodynia in migraineurs by a nationwide face-to-face questionnaire-based study by physicians.

METHODS

A total of 5323 households were examined for headache according to the diagnostic criteria of International Classification of Headache Disorders-II. Detailed headache features, premonitory signs, demographics, socio-economic status, and hormonal status of female individuals were analyzed with regard to the presence of allodynia in patients with definite migraine.

RESULTS

Allodynia was present in 61.1% of migraineurs in the general population of Turkey. The duration and severity of attacks (P<0.0001), photophobia (P=0.001), phonophobia, and also osmophobia (P<0.0001), as well as premonitory signs (P=0.018), showed significant associations with allodynia. Migraineurs with aura or family history of migraine more often reported allodynia in comparison with those without (P=0.001 and 0.028, respectively). Allodynic migraineurs had a higher rate of physician consults and high levels on the Migraine Disability Assessment questionnaire, reflecting increased burden of headache. Furthermore, migraineurs with allodynia had high probability of attacks close to menses. Migraine improved during pregnancy, but it worsened after menopause or during oral contraceptive use in individuals experiencing allodynia when compared with those without allodynia.

DISCUSSION

The duration, severity, and disability of migraine attacks, photophobia, phonophobia, and osmophobia, as well as premonitory signs, showed significant associations with allodynia in the general population. Moreover, migraineurs with aura or family history of migraine more often reported allodynia, and allodynic migraneurs were more sensitive to hormonal changes. Allodynia, which seems to indicate higher tendency to central sensitization, should be implemented in daily headache practice to predict the prognosis and high levels of migraineous involvement.

Assessment of Blink Reflex in Genetic Generalized Epilepsy Patients With Eyelid Myoclonia

Eyelid myoclonia (EM) with or without absences are a rare type of generalized seizures associated with a variety of epilepsy syndromes with an unknown pathophysiology. The aim of this study was to investigate the possible contribution of the brainstem structures in this underrecognized special type of seizures. Sixteen consecutive patients with EM, diagnosed with genetic generalized epilepsy (GGE) according to International League Against Epilepsy 2010 criteria were included. Brainstem excitabilities were examined by blink reflex (BR) studies. The results of BR studies in GGE patients with EM were statistically compared with 2 control groups; namely age- and gender-matched healthy volunteers and juvenile myoclonic epilepsy (JME) patients without any absences and using similar antiepileptic drugs. There were no statistical differences between the thresholds of the BR studies and the BR recovery curves in terms of amplitudes and areas of healthy subjects, JME patients and GGE patients with EM. Our findings do not support a profound interictal hyperexcitability in the BR-related brainstem structures of the GGE patients with EM. It can be considered that EM may be associated with excitability changes of the occipital cortex and other cortical areas.