***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective To investigate trigeminal sensory processing in patients with migraine using a novel “ nociception-specific ” blink reflex . Methods Seventeen patients with unilateral migraine headache were studied within 6 hours of onset . Blink reflexes were elicited with a st and ard stimulating electrode ( st and ard blink reflex ) and concentric stimulating electrode ( nociception-specific blink reflex ) during the acute migraine attack , after treatment with IV lysine acetylsalicylate ( 1,000 mg ) or oral zolmitriptan ( 5 mg ) and interictally . Results After st and ard stimulation , no differences were detected for the R1 and R2 onset latencies and areas under the curve ( AUC ) between the different time points and the headache and nonheadache side . Nociception-specific stimulation revealed a shortening of R2 onset latencies ( 44.3 ± 5.4 ms for headache side vs 48.9 ± 5.8 ms for nonheadache side ) during the acute migraine attack compared with the headache-free interval ( 49.8 ± 5.3 vs 49.8 ± 4.5 ms ) . The AUC of the R2 increased on the headache side by 680 % and on the nonheadache side by 230 % compared with the headache-free interval . Drug treatment parallel to pain relief increased the onset latencies  ( zolmitriptan : 48.0 ± 8.2 ms for headache side vs 52.3 ± 7.6 ms for nonheadache side ; lysine acetylsalicylate : 48.0 ± 5.0 ms for headache side vs 51.2 ± 5.6 ms for nonheadache side ) and reduced the AUC of R2  ( zolmitriptan by 45 % and lysine acetylsalicylate by 48 % ) . Conclusion The data suggest temporary sensitization of central trigeminal neurons during acute migraine attacks The aim of this study was to evaluate the function of pain modulating systems subserving diffuse noxious inhibitory controls ( DNICs ) in primary headaches . DNICs were examined in 24 migraineurs , 17 patients with chronic tension-type headache ( CTTH ) and 20 healthy subjects by means of nociceptive flexion RIII reflex and the cold pressor test ( CPT ) as heterotopic noxious conditioning stimulation ( HNCS ) . The subjective pain thresholds ( Tp ) and the RIII reflex threshold ( Tr ) were significantly lower in CTTH vs. controls . In controls a significant inhibition of the RIII reflex was observed during the CPT ( -30± , P < 0.05 ) . Conversely , migraine and CTTH patients  showed facilitation ( + 31± , P < 0.05 and + 40± , P < 0.01 , respectively ) of the RIII reflex during the HNCS . This study demonstrates a dysfunction in systems subserving DNICs in both migraine and CTTH . Impairment of endogenous supraspinal pain modulation systems may contribute to the development and /or maintenance of central sensitization in primary headaches OBJECTIVE This study aims to determine if cervical medial branch radiofrequency neurotomy reduces psychophysical indicators of augmented central pain processing and improves motor function in individuals with chronic whiplash symptoms . DESIGN Prospect i ve observational study of consecutive patients with healthy control comparison . SETTING Tertiary spinal intervention centre in Calgary , Alberta , Canada . SUBJECTS Fifty-three individuals with chronic whiplash associated disorder symptoms ( Grade 2 ) ; 30 healthy controls . METHODS Measures were made at four time points : two prior to radiofrequency neurotomy , and 1- and 3-months post-radiofrequency neurotomy . Measures included : comprehensive quantitative sensory testing ( including brachial plexus provocation test ) , nociceptive flexion reflex , and motor function ( cervical range of movement , superficial neck flexor activity during the craniocervical flexion test ) . Self-report pain and disability measures were also collected . One-way repeated measures analysis of variance and Friedman 's tests were performed to investigate the effect of time on the earlier measures . Differences between the whiplash and healthy control groups were investigated with two-tailed independent sample s t-test or Mann-Whitney tests . RESULTS Following cervical radiofrequency neurotomy , there were significant early ( within 1 month ) and sustained ( 3 months ) improvements in pain , disability , local and widespread hyperalgesia to pressure and thermal stimuli , nociceptive flexor reflex threshold , and brachial plexus provocation test responses as well as increased neck range of motion ( all P < 0.0001 ) . A nonsignificant trend for reduced muscle activity with the craniocervical flexion test ( P > 0.13 ) was measured . CONCLUSIONS Attenuation of psychophysical measures of augmented central pain processing and improved cervical movement imply that these processes are maintained by peripheral nociceptive input OBJECTIVES Activation of the trigeminovascular system and sensitisation of brainstem trigeminal nuclei are thought to play an important role in migraine . The aim of this study was to investigate the blink reflex and its habituation in patients with " chronic migraine " . METHODS We studied 35 patients suffering from " chronic migraine " ( IHS classification criteria ) outside and during a spontaneous attack , and 35 control subjects .  An EMG device with a specific habituation test program was used to elicit and record blink reflex responses and to r and omly repeat stimulations at different time intervals so as to induce habituation . RESULTS The R(1 ) and R(2 ) latencies , amplitudes and areas of the basal blink reflex were similar in patients studied both outside and during an attack as well as in control subjects , whereas the blink reflex habituation responses were markedly reduced in patients studied outside an attack . The percent changes in the R(2 ) areas from the baseline values , obtained when stimuli were delivered at time intervals of 10 , 5 , 4 , 3 , 2 and 1s , were statistically different ( p<0.01-p<0.001 ) from those of the same patients studied during a migraine attack and of those of control subjects . There was a significant correlation between decreased habituation of the blink reflex and a higher frequency of attacks . The stimulus intensities of the blink reflex ( multiples of the detection threshold intensities ) were significantly lower ( p<0.001 ) on the side affected , or more severely affected , by headache in patients studied during a migraine attack . CONCLUSIONS The decreased habituation of the blink reflex outside an attack reflects abnormal excitability in " chronic migraine " , which normalizes during the attacks . The inverse correlation between the frequency of attacks and habituation responses confirms the abnormal excitability induced by the high frequency of attacks . Central sensitisation mechanisms ( allodynia ) may explain the lower detection thresholds observed on the side affected by headache in patients during the attacks . SIGNIFICANCE The blink reflex and its habituation may help shed light on the subtle neurophysiological changes that occur in migraine patients between and during attacks Trigeminal and somatic nociceptive systems were studied in controls ( n = 15 ) , episodic migraine ( n = 16 ) , analgesics ( n = 14 ) and triptan-induced medication overuse headache ( MOH ) ( n = 15 ) before and after withdrawal . Patients with MOH and comorbid depressive symptoms and depression without headache were studied to investigate the influence of depression . Trigeminal nociception was studied by simultaneous registration of  pain-related cortical potentials ( PREP ) and  nociceptive blink reflex ( nBR ) following nociceptive-specific electrical stimulation of the forehead . Somatic nociception was evaluated using PREP of upper limbs . We found facilitation of both trigeminal and somatic PREP but not of nBR in MOH , which normalized after withdrawal . No differences were found comparing analgesics vs. triptan MOH . No differences were observed between controls and patients with episodic migraine and depression without headache . A transient facilitation was found of trigeminal and somatic nociceptive systems in MOH , which was more pronounced on a supraspinal level OBJECTIVE To determine whether abnormalities of peripheral and central nociceptive sensory input processing exist outside areas of spontaneous pain in patients with fibromyalgia ( FM ) as compared with controls , by using quantitative sensory testing ( QST ) and a neurophysiologic paradigm independent from subjective reports . METHODS A total of 164 out patients with FM who were attending a self-management program were invited to participate in the study . Data for 85 patients were available and were compared with those for 40 non-FM controls matched for age and sex .  QST was performed using thermal , mechanical , and electrical stimuli at locations of nonspontaneous pain . Pain assessment was 2-fold and included use of subjective scales and the spinal nociceptive flexion reflex ( NFR ) , a specific physiologic correlate for the objective evaluation of central nociceptive pathways . Question naires regarding quality of life and the impact of FM were available . RESULTS Participants were mainly middle-aged women , with a mean disease duration of 8 years . Between-group differences were significant for neurophysiologic , clinical , and quality of life measures . In patients with FM , peripheral QST showed significantly altered cold and heat pain thresholds , and tolerance to cold pain was radically reduced . The median NFR threshold in patients with FM ( 22.7 mA [ range 17.5 - 31.7 ] ) was significantly decreased compared with that in controls ( 33 mA [ range 28.1 - 41 ] ) . A cutoff value of < 27.6 mA for NFR provided sensitivity of 73 % and specificity of 80 % for detecting central allodynia in the setting of FM . CONCLUSION Our results strongly , although indirectly , point to a state of central hyperexcitability of the nociceptive system in patients with FM . The NFR can be used to assess central allodynia in FM . It may also help discriminate patients who may benefit from use of central ly acting analgesics Background : Visceral hypersensitivity has been evidence d in patients with irritable bowel syndrome ( IBS ) but its mechanisms remain poorly eluci date d. We investigated the spinal transmission of nociceptive signals in IBS patients by analysing the effects of rectal distensions on electromyographic recordings of the somatic nociceptive flexion ( RIII ) reflex , an objective index of spinal nociceptive processes . Methods : Fourteen IBS and 10 healthy volunteers were included in the study . Slow ramp ( 40 ml/min ) and rapid phasic ( 900 ml/min , 10 , 20 , 30 , and 40 mm Hg ) rectal distensions were r and omly performed while the RIII reflex evoked by electrical stimulation of the sural nerve at the ankle was continuously recorded from the ipsilateral biceps femoris . Results : In healthy volunteers , significant progressive inhibition of the RIII reflex was observed during slow ramp distension ( 61 (13)% of control values ) while biphasic effects ( facilitation and inhibition ) were observed during rapid distensions . In contrast , in IBS patients , the RIII reflex was significantly facilitated during slow ramp distension ( 139 (15)% of control values ) and inhibitions induced by rapid distensions were significantly reduced . Volumes of distension and rectal compliance were similar in both groups . Conclusions : Our results provide direct evidence that a hyperexcitability of spinal nociceptive processes is present in a large subgroup of IBS patients & NA ; The processing of pain‐related , body‐related and neutral words was assessed in chronic pain patients and matched healthy controls . During and after word presentation at perception threshold , electromyographic activity ( EMG ) , heart rate , skin conductance level and electroencephalographic ( EEG ) data from 11 electrode sites were recorded .  Startle responses were measured to suprathreshold word stimuli . Although the patients did not recognize more pain‐related words , they produced an enhanced left‐hemispheric N100 and N200 to pain‐related as compared to neutral words . In addition , the patients did not show a distinct P300 but a continuous positive shift to all words extending into the 800‐ms range . Skin conductance levels to the pain‐related words were also enhanced in patients only . These data partially support the notion of pain‐related implicit memory structures in the brain of chronic pain patients that may selectively draw attention to pain‐related stimuli and may thus enhance pain perception The aim of this study was to investigate central anti-nociceptive mechanisms of i.v . acetylsalicylic acid ( ASA ) and oral zolmitriptan ( ZOL ) in migraine patients and healthy subjects using the ‘ nociceptive ’ blink reflex ( nBR ) .  Twenty-eight migraine patients received ASA ( n = 14 , 1000 mg i.v ) or ZOL ( n = 14 , 5 mg p.o ) during the acute migraine attack and interictally . Thirty healthy subjects received either ASA or ZOL vs. placebo using a double blind cross over design . nBR was recorded in all patients and subjects before , 60 and 90 min after treatment . ASA and ZOL did not inhibit nBR responses in healthy subjects . Both ASA and ZOL  suppressed nBR responses  ( ASA by 68 % , ZOL by 78 % ) only during the acute attack but not interictally . The data suggest , that the anti-nociceptive effects of migraine drugs on the trigeminal nociceptive processing are different during and outside an acute migraine attack 
    Output:
    
Reflexive threshold was lower in people with clinical pain than it was in pain-free controls , but reflex size , latency , and duration were unaffected .
The pattern of difference was not consistent with sensitisation of nociceptive neurones , as these changes were not isolated to the affected body part but was more consistent with top-down cognitive control reflective of heightened protection of body tissue .
The pattern of modulation is dependent on potentially complex evaluative mechanisms .
We offer recommendations for future investigations and suggest that defensive reflex threshold may reflect a biomarker of a broader psychological construct related to bodily protection , rather than sensitisation of primary nociceptors , spinal nociceptors , or pain