Heat pain thresholds and cerebral event-related potentials following painful CO2 laser stimulation in chronic tension-type headache.

Current opinion concerning the pathophysiology of tension-type headache (TTH) and its related pericranial muscle tenderness proposes a primary role of central sensitization at the level of dorsalhorn/trigeminal nucleus as well as the supraspinal level. Investigation of these phenomena can be conducted using laser-evoked potentials (LEPs), which are objective and quantitative neurophysiological tools for the assessment of pain perception. In the present study we examined features of LEPs, as well as cutaneous heat-pain thresholds to laser stimulation, in relation to the tenderness of pericranial muscles in chronic TTH resulting from pericranial muscle disorder, during a pain-free phase. Twelve patients with TTH and 11 healthy controls were examined using the Total Tenderness Scoring (TTS) system. The stimulus was a laser pulse generated by a CO(2) laser. The dorsum of the hand and the cutaneous zones corresponding to pericranial muscles were stimulated. Subjective perception of stimulus intensity was assessed by a visual analogue scale. Two responses, the earlier named N2a and the last named P2, were considered; the absolute latency was measured at the highest peak of each response. The N2a-P2 components' peak-to-peak amplitude was detected. The heat pain threshold was similar in TTH patients and controls at the level of both the hand and pericranial skin. The TTS scores at almost all pericranial sites were higher in TTH patients than in normal controls. The amplitude of the N2a-P2 complex elicited by stimulation of the pericranial zone was greater in TTH patients than in controls; the amplitude increase was significantly associated with the TTS score. Our findings suggest that pericranial tenderness may be a primary phenomenon that precedes headache, and is mediated by a greater pain-specific hypervigilance at the cortical level.

Abnormal brain processing of cutaneous pain in patients with chronic migraine.

Syndromes with chronic daily headache include chronic migraine (CM). The reason for the transformation of migraine into chronic daily headache is still unknown. In this study, we aimed to evaluate heat pain thresholds and event-related potentials following CO(2)-laser thermal stimulation (LEPS) in hand and facial regions in patients with CM, to show changes in nociceptive brain responses related to dysfunction of pain elaboration at the cortical level. The results were compared with findings from normal control subjects and from subjects who suffer from migraine without aura. The effects of stimulus intensity, subjective pain perception and attention were monitored and compared with features of the LEPS. Twenty-five CM patients, 15 subjects suffering from migraine without aura and 15 normal control subjects were enrolled in the study. LEPS amplitude variation was reduced in CM patients with respect to the perceived stimulus intensity, in comparison with migraine without aura patients and control subjects. In both headache groups, the distraction from the painful laser stimulus induced by an arithmetic task failed to suppress the LEPS amplitude, in comparison with control subjects. These results suggest an abnormal cortical processing of nociceptive input in CM patients, which could lead to the chronic state of pain. In both headache groups, an inability to reduce pain elaboration during an alternative cognitive task emerged as an abnormal behaviour probably predisposing to migraine.

Paroxetine and fluoxetine effects on mood and cognitive functions in depressed nondemented elderly patients.

BACKGROUND: A large proportion of the elderly population complains of depressive symptoms. The ideal antidepressant for these patients, who often suffer from numerous concomitant diseases, should not worsen their cognitive functions and should be free of contraindications. METHOD: To assess the effects of 2 selective serotonin reuptake inhibitors on cognitive functions in elderly depressed patients (ICD-10 criteria), we conducted a double-blind, randomized, parallel-group, multicenter study comparing paroxetine (20-40 mg daily) and fluoxetine (20-60 mg daily) treatment for 1 year. Cognitive performance was evaluated by means of the Buschke Selective Reminding Test, the Blessed Information and Memory Test, the Clifton Assessment Schedule, the Cancellation Task Test, and the Wechsler Paired Word Test; the Hamilton Rating Scale for Depression (HAM-D) and the Clinical Anxiety Scale were administered to assess the course of depressive and anxiety symptoms, respectively. RESULTS: 242 patients were enrolled (mean +/- SD age = 75.4 +/- 6.6 years). During the study, no deterioration of cognition was observed; on the contrary, most of the tested cognitive functions improved. Good antidepressant efficacy was maintained for over 1 year with both drugs, based on the percentage of responders to treatment (patients achieving a HAM-D total score < 10; 60%). Both drugs showed a good tolerability and safety profile. CONCLUSION: The 2 antidepressants proved to be suitable for the long-term treatment of depression in the elderly and to be devoid of detrimental effects on the tested cognitive functions.

Abnormal brain processing of cutaneous pain in migraine patients during the attack.

We examined cutaneous pain thresholds using CO(2) laser stimuli during migraine attacks, and defined the evoked cortical potential characteristics. Ten patients without aura were studied during attacks and for at least 72 h subsequently. Pain stimuli were generated on the dorsum of both hands and the right and left supraorbital zones, using pulses from a CO(2) laser. Absolute latencies of scalp potentials were measured at the highest peak of each response component, and the peak-to-peak amplitudes of N2a-P2 components were recorded. Cutaneous pain thresholds were significantly reduced on both the symptomatic and non-symptomatic sides during the attack, in comparison with the headache-free phase. The N2a-P2 complexes also increased in amplitude during attacks in comparison with the pain-free side. Thus, cutaneous hyperalgesia occurs during migraine attack, and is subtended by central sensitization phenomena, probably involving the cortex.

High and low frequency transcutaneous electrical nerve stimulation inhibits nociceptive responses induced by CO2 laser stimulation in humans.

The aim of the study was to evaluate the effects of transcutaneous electric nerve stimulation (TENS) on CO(2) laser evoked potentials (LEPs) in 16 normal subjects. The volar side of the forearm was stimulated by 10 Hz TENS in eight subjects and by 100 Hz TENS in the remainder; the skin of the forearm was stimulated by CO(2) laser and the LEPs were recorded in basal conditions and soon after and 15 min after TENS. Both low and high frequency TENS significantly reduced the subjective rating of heat stimuli and the LEPs amplitude, although high frequency TENS appeared more efficacious. TENS seemed to exert a mild inhibition of the perception and processing of pain induced by laser Adelta fibres activation; the implications of these effects in the clinical employment of TENS remain to be clarified.

Insomnia, quality of life and psychopathological features.

Most of the studies about chronic insomnia focused only on specific features, providing in this way a partial outlook of the problem. The aim of this study was to examine a sample of chronic insomniacs from different points of view, by estimating the prevalence of stress, psychopathological symptoms, psychiatric disorders, changes in quality of life and illness behaviour. Forty-three patients (54.4%) experienced some psychosocial stressors in the last 6 months preceding the enrollment in the study. More than 55% of insomniacs reported symptoms of psychopathology. One or more than one psychiatric disorder was diagnosed in 61.5% of insomniacs. Life events could play a role in facilitating the transformation of a psychopathological symptom in a psychiatric disorder, since patients with a psychiatric diagnosis showed a higher percent of stress. The more noticeable disability in the group of insomniacs with psychiatric disorders and the absence of a corresponding worsening in illness behaviour suggests that insomniacs feelings about their health status are so negative to be not fatherly worsen by comorbidity in spite of a worsen disability. The evaluation of insomniacs should be as much detailed as possible, without neglecting tests for the evaluation of disability and illness behaviour, which are important not only for a correct diagnosis but also for monitoring the effects of therapies.

Modulation of trigeminal reflex excitability in migraine: effects of attention and habituation on the blink reflex.

The modulation of trigeminal reflex excitability in migraine patients was evaluated during the asymptomatic phase by studying the effects of attention, habituation and preconditioning stimulus on the R2 and R3 components of the blink reflex (BR). Fifty patients suffering from migraine without aura, 20 affected by migraine with aura and 35 sex- and age-matched controls were selected. In subgroups of migraine with-aura and without-aura patients, and normal controls, the blink reflex was elicited during different cognitive situations: (a) spontaneous mental activity; (b) stimulus anticipation; (c) recognition of target numbers. In the remaining subjects, R2 and R3 habituation was evaluated by repetitive stimulation at 1, 5, 10, 15, 20, 25 and 30 s intervals. The R2 and R3 recovery curves were also computed. A reduced R3 threshold with a normal pain threshold was found in migraine with-aura and without-aura patients; the R3 component was not significantly correlated with the pain thresholds in patients and controls. The R2 and R3 components were less influenced by the warning of the stimulus in migraine without-aura and migraine with-aura patients, in comparison with the control group. A slight increase of both R2 and R3 recovery after preconditioning stimulus was also observed in migraine patients, probably caused by a phenomenon of trigeminal hyperexcitability persisting after the last attack. The abnormal BR modulation by alerting expresses in migraine a dysfunction of adaptation capacity to environmental conditions, probably predisposing to migraine.

Early modifications of auditory event-related potentials in carriers of the Huntington's disease gene.

The P3 wave is one cognitive component of event-related potentials (ERP) used to investigate various types of dementia. The aim of this study was to use the odd-ball paradigm to evaluate the P3 in Huntington's Disease (HD) gene carriers who showed no symptoms of chorea, compared to a group of mildly affected HD patients. We selected 14 HD patients and six individuals who, despite testing positive for the HD gene, did not show any clinical evidence of the disease. Thirty-six normal subjects were also selected as controls. Statistical evaluation of N1, P2, N2 and P3 latencies and amplitudes was performed in each group. Both the N2 latency and the P3 latency corrected for age (cP3) were significantly correlated with the duration of illness in pooled symptomatic and presymptomatic gene carriers. However, these latencies did not correlate with any clinical scale or psychometric test, including WAIS subtests. As the individual P3 latency of the majority of HD patients and all presymptomatic gene carriers was distributed within normal confidence intervals, and no correlation existed between ERP parameters and the signs of illness progression, the data appear to provide preliminary evidence against the valence of P3 in detecting the early cognitive impairment of HD.

Topographic and dipolar analysis of laser-evoked potentials during migraine attack.

OBJECTIVE: The aim of this study was to perform further evaluation of laser-evoked potentials (LEPs) during migraine attacks using multichannel recording and topographic analysis. Specifically, this study aimed to confirm the pattern previously observed in acute migraine, while also defining the components of LEPs that are mainly modified during headache, as well as the correlation between features of LEPs and clinical variables. In addition, we aimed to conduct a dipolar source analysis of the main LEP waves in migraine patients to check the variability in the source location of LEPs during acute migraine. BACKGROUND: An amplitude enhancement of LEPs was previously detected during migraine attack using a single scalp derivation on the vertex; hyperalgesia to heat stimuli was also detected for both the face and hand. METHODS: Eighteen patients suffering from migraine without aura were analyzed. The supraorbital zones and the dorsum of the hand were stimulated on both the symptomatic and nonsymptomatic sides in all patients. The LEPs were recorded via 25 scalp electrodes. Dipolar source analysis of the P2 components was performed using a spherical model in all patients and using a realistic Magnetic Resonance model in four patients. RESULTS: During attacks, the later waves, and particularly the P2 component, were significantly enhanced; the amplitude of the P2 component obtained during the attack by stimulation of the supraorbital zone on the side of the headache was significantly correlated with the intensity of pain and the frequency of headache. In our patients, the P2 wave was generated in the anterior cingulate cortex, with a shift toward its rostrocaudal portion, and was mainly devoted to elaboration of the emotive compound of pain during migraine attack. CONCLUSIONS: Cortical activation by laser stimuli during migraine attack was confirmed. This effect was more pronounced in patients with a higher frequency of migraine attacks. This may be due to a lack of inhibitory control over the transmission of pain to the cortex. The increased activation of cortical areas devoted to attention and emotion may be linked to headache.