Motor cortex function in fibromyalgia: a pilot study involving near-infrared spectroscopy and co-recording of laser-evoked potentials.

Interaction between the motor and nociceptive systems seems to play an important role in chronic pain. In this pilot study we used a combination of functional near-infrared spectroscopy (FNIRS) and laserevoked potentials (LEPs) during concurrent finger tapping task and noxious laser stimulation in fibromyalgia (FM) patients and controls. The study included 9 healthy subjects and 15 FM patients. During concurrent FNIRS and LEP recording, participants were required either to remain in resting relaxed condition or to execute a finger tapping task with the right hand. In the control group, the left motor cortex showed increased oxyhaemoglobin levels, while the early N1 LEP component was reduced, during the finger tapping task. In FM patients, motor cortex oxyhaemoglobin concentrations were lower during movement, which did not reduce LEPs. The left motor cortex oxyhaemoglobin concentrations had 79.2% diagnostic accuracy. The interplay between motor and pain-related circuits seems to be dysfunctional in FM patients. These results may support a role for motor cortex modulation in the treatment of this disabling disease.

Nociceptive blink reflex habituation biofeedback in migraine.

Reduced habituation of the nociceptive blink reflex (NBR) is considered a trait marker for genetic predisposition to migraine. In this open-label randomized controlled study, we aimed to test the efficacy of a biofeedback training based on learning of habituation of the NBR (NBR biofeedback) compared with pharmacological (topiramate) treatment and NBR biofeedback plus topiramate treatment in a cohort of migraine without aura patients eligible for prophylaxis. Thirty-three migraine patients were randomly assigned to three months of treatment with: 1) NBR biofeedback, 2) NBR biofeedback plus topiramate 50 mg (b.i.d.), or 3) topiramate 50 mg (b.i.d.). Frequency of headache and disability changes were the main study outcomes. Anxiety, depression, sleep, fatigue, quality of life, allodynia and pericranial tenderness were also evaluated. NBR biofeedback reduced the R2 area, without improving R2 habituation. However, it reduced the frequency of headache and disability, similarly to the combined treatment and topiramate alone. Reduced habituation of the NBR is a stable neurophysiological pattern, scarcely modifiable by learning procedures. Training methods able to act on stress-related responses may modulate cortical mechanisms inducing migraine onset and trigeminal activation under stressful trigger factors.

Effects of anodal TDCS stimulation of left parietal cortex on visual spatial attention tasks in men and women across menstrual cycle.

Sex hormonal variations have been shown to affect functional cerebral asymmetries in cognitive domains, contributing to sex-related differences in functional cerebral organization. The aim of this study was to investigate spatial attention by means of a bisection line test and computer-supported attention task during the menstrual cycle in healthy women compared to men, in basal condition and under Transcranial Direct Current Stimulation (TDCS) of the left parietal cortex. Women were studied during the menses, follicular and luteal phases, ascertained by transvaginal ultrasounds. In basal conditions, women showed a clear deviation toward the right in the bisection line test during the menstrual phase, similarly to men. The midpoint recognition in the computer-supported attention task was not influenced by the menstrual cycle for women, while men showed a significant increase in errors toward the left side. The anodal activation of the left parietal cortex did not affect the line bisection task, while in men it reduced the total amount of errors in midpoint recognition observed in the computer supported attention task. The hand-use effect demonstrated by the bisection-line test could be influenced by estrogen fluctuations, while the right hemisphere prevalence in spatial attention appears to be gender-related and scarcely influenced by the menstrual cycle. The left parietal cortex seems to exert a scarce effect on hand-use effect, while its activation is able to revert sex related right hemisphere supremacy.