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To study the effects of a standard acute medication withdrawal program on short-term cortical plasticity mechanisms in patients with medication overuse headache (MOH). Thirteen patients with MOH and 16 healthy volunteers underwent repetitive transcranial magnetic stimulation (rTMS) over the left motor cortex; in patients with MOH, recordings were performed before and after a 3-week medication withdrawal program. Ten trains of 10 stimuli each (120% resting motor threshold) were delivered at 1 Hz or 5 Hz in two separate sessions in a randomised order. Motor evoked potential (MEP) amplitudes were measured from the right first dorsal interosseous muscle and the slope of the linear regression line from the first to the tenth stimuli was calculated for each participant. All subjects exhibited MEP amplitude inhibition in response to 1 Hz rTMS. Alternatively, the 5-Hz trains of rTMS inhibited rather than potentiated MEP amplitudes in patients with MOH. The physiological potentiating effect of 5 Hz rTMS on MEP amplitudes was restored after drug withdrawal and in proportion with the percentage reduction in monthly headache days in patients with MOH. The results suggest that acute medication withdrawal normalises brain responses in patients with MOH. Clinical improvements after medication withdrawal may reflect the reversal of neurophysiological dysfunction. Accordingly, medication withdrawal should be offered to patients with MOH as early as possible in order to prevent the development of more pronounced alterations in brain plasticity.

Background Neurophysiological investigations have demonstrated that there are distinctive fluctuations in the brain’ se lectric signals between the ictal and interictal periods of recurrent migraine. Whether structural plasticity of the brain is also an important feature of episodic migraine remains unresolved. Aim We therefore investigated the possibility that there are fluctuations over time in whole brain grey matter morphometry of patients affected by episodic migraine without aura (MO). Method Twenty-four patients with untreated MO underwent MRI scans (3-Tesla Siemens Verio) during (n = 10) or between attacks (n = 14) and were compared to a group of 15 healthy volunteers (HV). We then performed voxelbased-morphometry (VBM) analysis of structural T1-weighted MRI scans to determine if changes in brain structure were observed over the course of the migraine cycle. Results During the interictal phase, MO patients had a significantly lower grey matter (GM) density within the right inferior parietal lobule, right temporal inferior gyrus, right superior temporal gyrus, and left temporal pole than did HV. During attacks, GM density increased within the left temporal pole, bilateral insula, and right lenticular nuclei, but no areas exhibited decreased GM density. Conclusion The morphometric GM changes between ictal and interictal phases reported in the present study suggest that abnormal structural plasticity may be an important mechanism of migraine pathology. Given the functional neuroanatomy of these areas, our findings suggest that migraine is a condition associated with global dysfunction of multisensory integration and memory processing. No conflict of interest.

The most common mononeuropathy in the lower extremity involves the nerve. We retrospectively evaluated the etiological predisposing factors and clinical-neurophysiological features of 36 patients affected by peroneal mononeuropathy (PM). In 30 patients, a clear predisposing factor was identified. PM was more frequently perioperative (11 cases), associated with axonal involvement. Unexpectedly, PM was not only due to surgery close to the peroneal region, but was mostly associated with hip surgery and, rarely, with thoracic-abdominal surgery. A postural predisposing factor of PM was also frequently observed, usually associated with a pure conduction block. Conversely, most patients with bedridden predisposing factor presented axonal involvement, which was rarely associated with conduction block. In 25 of 36 PM cases, a long-term follow-up lead to an improvement (12 cases) or to good recovery (13 cases) of PM. In conclusion, our study shows that: (1) in most PM cases it is possible to identify a predisposing factor; (2) there is a good correlation between predisposing factor and neurophysiological involvement, and (3) PM usually has usually a good prognosis.

Background and objectives Studies of spontaneous EEG and visual or somatosensory evoked high frequency oscillations indicate that the abnormal fluctuations of cortical responsivity over time in relation to the migraine attack could be due to abnormal thalamic control. Here we searched for possible structural changes in the thalamus of migraineurs by mean of acquiring diffusion tensor magnetic resonance imaging (MRI). This MRI technique provides quantitative data on water molecular motion, as a marker of tissue structure. Materials & Method – Seventeen untreated migraine without aura (MO) patients underwent MRI scan (3-Tesla Siemens Gyroscan) during (n=7) and between attacks (n=10) and were compared to a group of 14 healthy volunteers (HV). We examined fractional anisotropy (FA) and mean diffusivity (MD) in the thalamus.