The habituation to sensory stimuli of different modalities is reduced in migraine patients. However, the habituation to pain has never been evaluated. Our aim was to assess the nociceptive pathway function and the habituation to experimental pain in patients with migraine. Scalp potentials were evoked by CO(2) laser stimulation (laser evoked potentials, LEPs) of the hand and facial skin in 24 patients with migraine without aura (MO), 19 patients with chronic tension-type headache (CTTH), and 28 control subjects (CS). The habituation was studied by measuring the changes of LEP amplitudes across three consecutive repetitions of 30 trials each (the repetitions lasted 5 min and were separated by 5-min intervals). The slope of the regression line between LEP amplitude and number of repetitions was taken as an index of habituation. The LEPs consisted of middle-latency, low-amplitude responses (N1, contralateral temporal region, and P1, frontal region) followed by a late, high-amplitude, negative-positive complex (N2/P2, vertex). The latency and amplitude of these responses were similar in both patients and controls. While CS and CTTH patients showed a significant habituation of the N2/P2 response, in MO patients this LEP component did not develop any habituation at all after face stimulation and showed a significantly lower habituation than in CS after hand stimulation. The habituation index of the vertex N2/P2 complex exceeded the normal limits in 13 out of the 24 MO patients and in none of the 19 CTTH patients (P<0.0001; Fisher's exact test). Moreover, while the N1-P1 amplitude showed a significant habituation in CS after hand stimulation, it did not change across repetitions in MO patients. In conclusion, no functional impairment of the nociceptive pathways, including the trigeminal pathways, was found in either MO or CTTH patients. But patients with migraine had a reduced habituation, which probably reflects an abnormal excitability of the cortical areas involved in pain processing.
The objectives of this paper are to evaluate the efficacy and tolerability of topiramate, given at the dose of 100 mg/day, in the prophylactic treatment of migraine. The hypothesis that migraine is the result of a condition of neuronal hyperexcitability and the quest for drugs that are able to limit the number of crises justifies the attempt to utilise the new antiepileptic drugs in the prophylaxis of this pathology, which is so important due to its high prevalence and due to the high disability it causes. The study was randomised double-blind versus placebo, lasting 16 weeks, and was preceded by a run-in period of 4 weeks. One hundred and fifteen patients were randomly allocated to treatment with topiramate (TPM) or placebo: 35 patients completed the study in the TPM group and 37 patients in the placebo group. At the end of the double-blind phase of study, in the TPM group, we recorded a significant reduction in the frequency of migraine crises (from 5.26 at baseline to 2.60 in the last 4 weeks), a significant reduction in the quantity of symptomatic drugs taken as compared to the placebo control group (from 6.17+/-1.80 SD to 2.57+/-0.80) and a significant downward trend in the number of days of disability over the 16-week period of therapy. In the TPM group, side effects were transient and well tolerated. TPM has thus proven its efficacy and tolerability in the prophylaxis of migraine.
8 Children surgically treated for posterior fossa arachnoid cyst are described. In all the cases an enlarging head was the presenting sign; intracranial hypertension was evident in 6 patients; 2 children were clinically regarded as being affected by ‘arrested’ hydrocephalus. Preoperative subarachnoid lumbar infusion tests (8 cases) and prolonged intraventricular CSF pressure recordings (2 cases) demonstrated abnormal CSF dynamics in 6 cases. Ultramicroscopic examinations of the cyst wall (4 cases) suggest alterations in the anatomical arrangement of the arachnoid membrane, which supports the hypothesis of maldevelopment as the origin of the lesion.
The deficient habituation of the vertex N2/P2 complex was partly restored after successful treatment of medication-overuse headache, reflecting a modification in pain-processing pathways.
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