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Lars Arendtnielsen - One of the best experts on this subject based on the ideXlab platform.

  • somatosensory and trophic findings in the Referred Pain area in patients with kidney stone disease
    Scandinavian Journal of Pain, 2013
    Co-Authors: Katja Venborg Pedersen, Lars Arendtnielsen, Asbjorn Mohr Drewes, Ole Graumann, Susanne Sloth Osther, Anne Estrup Olesen, Palle Jorn Sloth Osther
    Abstract:

    Background and purpose Visceral and somatic afferents activate the same neuronal structures in the central nervous system. Assessing somatosensory function and trophic changes in the Referred Pain area may therefore indirectly increase information on mechanisms involved in Painful visceral diseases. The aim of this study was to evaluate the sensory and trophic changes in the flank corresponding to the Referred Pain area in patients with kidney stone disease. Methods A total of 24 patients with unilateral Pain-causing kidney stone disease were studied before and after endoscopic percutaneous kidney stone surgery. Trophic changes and sensitivity on the affected and on the contra-lateral side in the Pain free period were investigated. For this purpose we used standardized experimental sensory testing including pressure stimulation and electrical (single and repeated) skin stimulation. Five repeated stimuli were used to investigate temporal summation (increased responses to repeated stimuli). To investigate trophic changes ultrasound as well as CT-scan was used, since the latter is considered more precise for exact tissue layer measurements. Results The Pain tolerance thresholds to pressure and Pain thresholds to electrical stimulation were not significantly different on the two sides (all P>0.1). After surgery no significant alterations in sensitivity were detected, but there was a tendency to higher Pain thresholds to electrical stimuli on the affected side (single stimuli P=0.06; repeated stimuli P=0.09). No trophic changes were observed (all P>0.3), and there were no relations between the Pain thresholds or trophic findings and the number of colics (all P >0.08). Conclusion In patients with unilateral Pain-causing kidney stone disease the Pain to experimental pressure and electrical stimuli were comparable on the affected and contra-lateral side. For the first time a CT-scan was used to evaluate tissue thickness in the Referred Pain area. No trophic changes were seen in the muscle or subcutaneous tissue at the affected side, and there were no correlations between the Pain thresholds or trophic findings and the patients history of number of colics. After the operation no significant alterations in sensitivity were detected. Implications This study could not confirm previous studies showing Referred hyperalgesia in the skin and trophic changes in the Referred Pain area to Painful visceral disease. Differences in the Pain intensity/duration between different diseases and hence the corresponding central neuronal changes may explain the negative findings in the present study.

  • reproduction of overall spontaneous Pain pattern by manual stimulation of active myofascial trigger points in fibromyalgia patients
    Arthritis Research & Therapy, 2011
    Co-Authors: Hongyou Ge, Thomas Gravennielsen, Cesar Fernandezdelaspenas, Bente Danneskioldsamsoe, Ying Wang, Lars Arendtnielsen
    Abstract:

    Introduction: It has previously been reported that local and Referred Pain from active myofascial trigger points (MTPs) in the neck and shoulder region contribute to fibromyalgia (FM) Pain and that the Pain pattern induced from active MTPs can reproduce parts of the spontaneous clinical FM Pain pattern. The current study investigated whether the overall spontaneous FM Pain pattern can be reproduced by local and Referred Pain from active MTPs located in different muscles. Methods: A spontaneous Pain pattern in FM was recorded in 30 FM patients and 30 healthy subjects served as controls. Local and Referred Pain patterns induced from active (patients) and latent (controls) MTPs were recorded following manual stimulation. The existence of MTPs was confirmed by intramuscular electromyographical registration of spontaneous electrical activity. Results: Local and Referred Pain areas induced from key active MTPs in FM were larger than Pain areas from latent MTPs in healthy controls (P 0.05). The induced Pain area was positively associated with current spontaneous Pain intensity in FM (P < 0.01). The locations of key active MTPs in FM patients were found to have latent MTPs in healthy subjects. The muscles containing key active MTPs in FM are often observed in the muscles of extensor digitorum, trapezius, infraspinatus in the upper part of the body and of quadratus lumborum, gluteus medius in the lower part of the body. Conclusions: The overall spontaneous FM Pain pattern can be reproduced by mechanical stimulation of active MTPs located in different muscles, suggesting that fibromyalgia Pain is largely composed of Pain arising from muscle Pain and spasm. Targeting active MTPs and related perpetuating factors may be an important strategy in FM Pain control. Trial registration: ISRCTN ISRCTN43167547.

  • sustained nociceptive mechanical stimulation of latent myofascial trigger point induces central sensitization in healthy subjects
    The Journal of Pain, 2010
    Co-Authors: Yimeng Xu, Hongyou Ge, Lars Arendtnielsen
    Abstract:

    UNLABELLED: The aim of the study is to test if sustained nociceptive mechanical stimulation (SNMS) of latent myofascial trigger points (MTrPs) induces widespread mechanical hyperalgesia. SNMS was obtained by inserting and retaining an intramuscular electromyographic (EMG) needle within a latent MTrP or a nonMTrP in the finger extensor muscle for 8 minutes in 12 healthy subjects. Pain intensity (VAS) and Referred Pain area induced by SNMS were recorded. Pressure Pain threshold (PPT) was measured immediately before and after, and 10-, 20-, and 30-minutes after SNMS at the midpoint of the contralateral tibialis anterior muscle. Surface and intramuscular EMG during SNMS were recorded. When compared to nonMTrPs, maximal VAS and the area under VAS curve (VASauc) were significantly higher and larger during SNMS of latent MTrPs (both, P < .05); there was a significant decrease in PPT 10 minutes, 20 minutes, and 30 minutes postSNMS of latent MTrPs (all, P < .05). Muscle cramps following SNMS of latent MTrPs were positively associated with VASauc (r = .72, P = .009) and Referred Pain area (r = .60, P = .03). Painful stimulation of latent MTrPs can initiate widespread central sensitization. Muscle cramps contribute to the induction of local and Referred Pain. PERSPECTIVE: This study shows that MTrPs are one of the important peripheral Pain generators and initiators for central sensitization. Therapeutic methods for decreasing the sensitivity and motor-unit excitability of MTrPs may prevent the development of muscle cramps and thus decrease local and Referred Pain.

  • sustained nociceptive mechanical stimulation of latent myofascial trigger point induces central sensitization in healthy subjects
    The Journal of Pain, 2010
    Co-Authors: Lars Arendtnielsen
    Abstract:

    Abstract The aim of the study is to test if sustained nociceptive mechanical stimulation (SNMS) of latent myofascial trigger points (MTrPs) induces widespread mechanical hyperalgesia. SNMS was obtained by inserting and retaining an intramuscular electromyographic (EMG) needle within a latent MTrP or a nonMTrP in the finger extensor muscle for 8 minutes in 12 healthy subjects. Pain intensity (VAS) and Referred Pain area induced by SNMS were recorded. Pressure Pain threshold (PPT) was measured immediately before and after, and 10-, 20-, and 30-minutes after SNMS at the midpoint of the contralateral tibialis anterior muscle. Surface and intramuscular EMG during SNMS were recorded. When compared to nonMTrPs, maximal VAS and the area under VAS curve (VASauc) were significantly higher and larger during SNMS of latent MTrPs (both, P P r = .72, P = .009) and Referred Pain area ( r = .60, P = .03). Painful stimulation of latent MTrPs can initiate widespread central sensitization. Muscle cramps contribute to the induction of local and Referred Pain. Perspective This study shows that MTrPs are one of the important peripheral Pain generators and initiators for central sensitization. Therapeutic methods for decreasing the sensitivity and motor-unit excitability of MTrPs may prevent the development of muscle cramps and thus decrease local and Referred Pain.

  • Referred Pain from muscle trigger points in the masticatory and neck shoulder musculature in women with temporomandibular disoders
    The Journal of Pain, 2010
    Co-Authors: Cesar Fernandezdelaspenas, Lars Arendtnielsen, Peter Svensson, Fernando Galandelrio, Cristina Alonsoblanco, Rodrigo Jimenezgarcia
    Abstract:

    Abstract Our aim was to describe the Referred Pain patterns and size of areas of trigger points (TrPs) in the masticatory and neck-shoulder muscles of women with myofascial temporomandibular disorders (TMD). Twenty-five women with myofascial TMD and 25 healthy matched women participated. Bilateral temporalis, deep masseter, superficial masseter, sternocleidomastoid, upper trapezius and suboccipital muscles were examined for TrPs by an assessor blinded to the subjects' condition. TrPs were identified with manual palpation and categorized into active and latent according to proposed criteria. The Referred Pain areas were drawn on anatomical maps, digitalized, and measured. The occurrence of active ( P P = .04) were different between groups. In all muscles, there were significantly more active and latent TrP in patients than controls ( P P P P P P P > .703). The local and Referred Pain elicited from active TrPs in the masticatory and neck-shoulder muscles shared similar Pain pattern as spontaneous TMD, which supports the concept of peripheral and central sensitization mechanisms in myofascial TMD. Perspective The current study showed the existence of multiple active muscle TrPs in the masticatory and neck-shoulder muscles in women with myofascial TMD Pain. The local and Referred Pain elicited from active TrPs reproduced Pain complaints in these patients. Further, Referred Pain areas were larger in TMD Pain patients than in healthy controls. The results are also in accordance with the notion of peripheral and central sensitization mechanisms in patients with myofascial TMD.

Cesar Fernandezdelaspenas - One of the best experts on this subject based on the ideXlab platform.

  • characteristics of Referred muscle Pain to the head from active trigger points in women with myofascial temporomandibular Pain and fibromyalgia syndrome
    Journal of Headache and Pain, 2012
    Co-Authors: Cristina Alonsoblanco, Cesar Fernandezdelaspenas, Peter Svensson, Fernando Galandelrio, Ana I Delallaverincon, Pedro Zarcomoreno
    Abstract:

    Our aim was to compare the differences in the prevalence and the anatomical localization of Referred Pain areas of active trigger points (TrPs) between women with myofascial temporomandibular disorder (TMD) or fibromyalgia (FMS). Twenty women (age 46 ± 8 years) with TMD and 20 (age 48 ± 6 years) with FMS were recruited from specialized clinic. Bilateral temporalis, masseter, sternocleidomastoid, upper trapezius, and suboccipital muscles were examined for TrPs. TrPs were identified by palpation and considered active when the Pain reproduced familiar Pain symptom experienced by the patient. The Referred Pain areas were drawn on anatomical maps, digitalized and also measured. A new analysis technique based on a center of gravity (COG) method was used to quantitative estimate of the localization of the TrP Referred Pain areas. Women with FMS exhibited larger areas of usual Pain symptoms than women with myofascial TMD (P < 0.001). The COG coordinates of the usual Pain on the frontal and posterior Pain maps were located more superior in TMD than in FMS. The number of active TrPs was significantly higher in TMD (mean ± SD 6 ± 1) than in FMS (4 ± 1) (P = 0.002). Women with TMD exhibited more active TrPs in the temporalis and masseter muscles than FMS (P < 0.01). Women with FMS had larger Referred Pain areas than those with TMD for sternocleidomastoid and suboccipital muscles (P < 0.001). Significant differences within COG coordinates of TrP Referred Pain areas were found in TMD, the Referred Pain was more pronounced in the orofacial region, whereas the Referred Pain in FMS was more pronounced in the cervical spine. This study showed that the Referred Pain elicited from active TrPs shared similar patterns as usual Pain symptoms in women with TMD or FMS, but that distinct differences in TrP prevalence and location of the Referred Pain areas could be observed. Differences in location of Referred Pain areas may help clinicians to determine the most relevant TrPs for each Pain syndrome in spite of overlaps in Pain areas.

  • Referred Pain from myofascial trigger points in head neck shoulder and arm muscles reproduces Pain symptoms in blue collar manual and white collar office workers
    The Clinical Journal of Pain, 2012
    Co-Authors: Cesar Fernandezdelaspenas, Ricardo Ortegasantiago, Christian Grobli, Christine Stebler Fischer, Daniel Boesch, Philippe Froidevaux, Lilian Stocker, Richard Weissmann, Javier Gonzaleziglesias
    Abstract:

    Objective: To describe the prevalence and Referred Pain area of trigger points (TrPs) in blue-collar (manual) and white-collar (office) workers, and to analyze if the Referred Pain pattern elicited from TrPs completely reproduces the overall spontaneous Pain pattern. Methods: Sixteen (62% women) blue-collar and 19 (75% women) white-collar workers were included in this study. TrPs in the temporalis, masseter, upper trapezius, sternocleidomastoid, splenius capitis, oblique capitis inferior, levator scapulae, scalene, pectoralis major, deltoid, infraspinatus, extensor carpi radialis brevis and longus, extensor digitorum communis, and supinator muscles were examined bilaterally (hyper-sensible tender spot within a palpable taut band, local twitch response with snapping palpation, and elicited Referred Pain pattern with palpation) by experienced assessors blinded to the participants’ condition. TrPs were considered active when the local and Referred Pain reproduced any symptom and the patient recognized the Pain as familiar. The Referred Pain areas were drawn on anatomic maps, digitized, and measured. Results: Blue-collar workers had a mean of 6 (SD: 3) active and 10 (SD: 5) latent TrPs, whereas white-collar workers had a mean of 6 (SD: 4) active and 11 (SD: 6) latent TrPs (P>0.548). No significant differences in the distribution of active and latent TrPs in the analyzed muscles between groups were found. Active TrPs in the upper trapezius, infraspinatus, levator scapulae, and extensor carpi radialis brevis muscles were the most prevalent in both groups. Significant differences in Referred Pain areas between muscles (P<0.001) were found; pectoralis major, infraspinatus, upper trapezius, and scalene muscles showed the largest Referred Pain areas (P<0.01), whereas the temporalis, masseter, and splenius capitis muscles showed the smallest (P<0.05). The combination of the Referred Pain from TrPs reproduced the overall clinical Pain area in all participants. Conclusions: Blue-collar and white-collar workers exhibited a similar number of TrPs in the upper quadrant musculature. The Referred Pain elicited by active TrPs reproduced the overall Pain pattern. The distribution of TrPs was not significantly different between groups. Clinicians should examine for the presence of muscle TrPs in blue-collar and white-collar workers.

  • prevalence and anatomical localization of muscle Referred Pain from active trigger points in head and neck musculature in adults and children with chronic tension type headache
    Pain Medicine, 2011
    Co-Authors: Cristina Alonsoblanco, Cesar Fernandezdelaspenas, Juan A Pareja, Peter Svensson, Daniel Martin Fernandezmayoralas, Ana I Delallaverincon
    Abstract:

    Objective.  To compare differences in the prevalence and the anatomical localization of the Referred Pain areas of active trigger points (TrPs) in head and neck musculature between adults and children with chronic tension-type headache (CTTH). Design.  A cross-sectional study. Setting.  Some studies had found that Referred Pain from active TrPs reproduce the head Pain pattern in adults. No study has compared clinical differences between Referred Pain patterns elicited by active TrPs between adults and children with CTTH. Patients.  Twenty adults (10 men, 10 women, mean age: 41 ± 11 years) and 20 children (10 boys, 10 girls, mean age: 8 ± 2 years) with CTTH were included. Outcome Measures.  Bilateral temporalis, sternocleidomastoid, upper trapezius, and suboccipital muscles were examined for TrPs. TrPs were identified by palpation and considered active when local and Referred Pains reproduce the headache Pain attacks. The Referred Pain areas were drawn on anatomical maps, digitalized, and also measured. An analysis technique based on a center of gravity (COG) method was used to provide a quantitative estimate of the localization of the TrP Referred Pain areas. Results.  Adults with CTTH exhibited a greater years with headache, higher intensity, and longer headache duration (P < 0.05) compared with children. The COG coordinates of the spontaneous Pain on the dominant side were located more anterior (higher X-value), and spontaneous Pain in the frontal and posterior areas was located more inferior (lower Y-value) in adults than in children. The number of active muscle TrPs was significantly higher (P = 0.001) in adults with CTTH (mean ± standard deviation [SD]: 4 ± 0.8) as compared with children (mean ± SD: 3 ± 0.7). Children with CTTH had larger Referred Pain areas than adults for upper trapezius, sternocleidomastoid, and temporalis (P < 0.001) muscles. The COG coordinates of the Referred Pain areas of temporalis and sternocleidomastoid muscle TrPs were more inferior (lower Y-values) in adults than in children with CTTH. Conclusions.  This study showed that the Referred Pain elicited from active TrPs shared similar Pain patterns as spontaneous CTTH in adults and children. Differences in TrP prevalence and location of the Referred Pain areas can be observed between adults and children with CTTH.

  • multiple active myofascial trigger points reproduce the overall spontaneous Pain pattern in women with fibromyalgia and are related to widespread mechanical hypersensitivity
    The Clinical Journal of Pain, 2011
    Co-Authors: Cristina Alonsoblanco, Cesar Fernandezdelaspenas, Hongyou Ge, Pedro Zarcomoreno, Matilde Moralescabezas, Mariano Florezgarcia
    Abstract:

    Objectives: To determine whether the local and Referred Pain from active myofascial trigger points (MTrPs) reproduce the overall spontaneous fibromyalgia syndrome (FMS) Pain pattern and whether widespread pressure hypersensitivity is related to the presence of widespread active MTrPs in FMS. Methods: Forty-four women with FMS (mean age: 47 ± 8 y) and 50 comparable healthy women (age: 48 ± 7 y) participated in the study. MTrPs in the temporalis, masseter, upper trapezius, splenius capitis, sternocleidomastoid, suboccipital, levator scapulae, scalene, pectoralis major, extensor carpi radialis brevis, extensor digitorum communis, gluteus maximus, piriformis, vastus medialis, and tibialis anterior muscles were explored. Pressure Pain thresholds over 18 tender points specified in the 1990 American College of Rheumatology for FMS were also assessed by an assessor blinded to the condition of the participants. Results: The mean ± SD number of MTrPs for each woman with FMS was 11 ± 3, of which 10 ± were active MTrPs and the remaining 1 ± 1 were latent. Healthy controls only had latent MTrPs (mean±SD: 2 ± 1). The combination of the Referred Pain patterns from active MTrPs fully reproduced the overall spontaneous clinical Pain area in patients with FMS. Patients with FMS had significant lower PPT compared with controls (P < 0.001). Within FMS, a significant positive correlation was found between the number of active MTrPs and spontaneous Pain intensity (r s = 0.455; P = 0.002). Conclusions: The local and Referred Pain elicited from widespread active MTrPs fully reproduced the overall spontaneous clinical Pain area in patients with FMS. Widespread mechanical Pain hypersensitivity was related to a greater number of active MTrPs. This study suggests that nociceptive inputs from active MTrPs may contribute to central sensitization in FMS.

  • reproduction of overall spontaneous Pain pattern by manual stimulation of active myofascial trigger points in fibromyalgia patients
    Arthritis Research & Therapy, 2011
    Co-Authors: Hongyou Ge, Thomas Gravennielsen, Cesar Fernandezdelaspenas, Bente Danneskioldsamsoe, Ying Wang, Lars Arendtnielsen
    Abstract:

    Introduction: It has previously been reported that local and Referred Pain from active myofascial trigger points (MTPs) in the neck and shoulder region contribute to fibromyalgia (FM) Pain and that the Pain pattern induced from active MTPs can reproduce parts of the spontaneous clinical FM Pain pattern. The current study investigated whether the overall spontaneous FM Pain pattern can be reproduced by local and Referred Pain from active MTPs located in different muscles. Methods: A spontaneous Pain pattern in FM was recorded in 30 FM patients and 30 healthy subjects served as controls. Local and Referred Pain patterns induced from active (patients) and latent (controls) MTPs were recorded following manual stimulation. The existence of MTPs was confirmed by intramuscular electromyographical registration of spontaneous electrical activity. Results: Local and Referred Pain areas induced from key active MTPs in FM were larger than Pain areas from latent MTPs in healthy controls (P 0.05). The induced Pain area was positively associated with current spontaneous Pain intensity in FM (P < 0.01). The locations of key active MTPs in FM patients were found to have latent MTPs in healthy subjects. The muscles containing key active MTPs in FM are often observed in the muscles of extensor digitorum, trapezius, infraspinatus in the upper part of the body and of quadratus lumborum, gluteus medius in the lower part of the body. Conclusions: The overall spontaneous FM Pain pattern can be reproduced by mechanical stimulation of active MTPs located in different muscles, suggesting that fibromyalgia Pain is largely composed of Pain arising from muscle Pain and spasm. Targeting active MTPs and related perpetuating factors may be an important strategy in FM Pain control. Trial registration: ISRCTN ISRCTN43167547.

Juan A Pareja - One of the best experts on this subject based on the ideXlab platform.

  • prevalence and anatomical localization of muscle Referred Pain from active trigger points in head and neck musculature in adults and children with chronic tension type headache
    Pain Medicine, 2011
    Co-Authors: Cristina Alonsoblanco, Cesar Fernandezdelaspenas, Juan A Pareja, Peter Svensson, Daniel Martin Fernandezmayoralas, Ana I Delallaverincon
    Abstract:

    Objective.  To compare differences in the prevalence and the anatomical localization of the Referred Pain areas of active trigger points (TrPs) in head and neck musculature between adults and children with chronic tension-type headache (CTTH). Design.  A cross-sectional study. Setting.  Some studies had found that Referred Pain from active TrPs reproduce the head Pain pattern in adults. No study has compared clinical differences between Referred Pain patterns elicited by active TrPs between adults and children with CTTH. Patients.  Twenty adults (10 men, 10 women, mean age: 41 ± 11 years) and 20 children (10 boys, 10 girls, mean age: 8 ± 2 years) with CTTH were included. Outcome Measures.  Bilateral temporalis, sternocleidomastoid, upper trapezius, and suboccipital muscles were examined for TrPs. TrPs were identified by palpation and considered active when local and Referred Pains reproduce the headache Pain attacks. The Referred Pain areas were drawn on anatomical maps, digitalized, and also measured. An analysis technique based on a center of gravity (COG) method was used to provide a quantitative estimate of the localization of the TrP Referred Pain areas. Results.  Adults with CTTH exhibited a greater years with headache, higher intensity, and longer headache duration (P < 0.05) compared with children. The COG coordinates of the spontaneous Pain on the dominant side were located more anterior (higher X-value), and spontaneous Pain in the frontal and posterior areas was located more inferior (lower Y-value) in adults than in children. The number of active muscle TrPs was significantly higher (P = 0.001) in adults with CTTH (mean ± standard deviation [SD]: 4 ± 0.8) as compared with children (mean ± SD: 3 ± 0.7). Children with CTTH had larger Referred Pain areas than adults for upper trapezius, sternocleidomastoid, and temporalis (P < 0.001) muscles. The COG coordinates of the Referred Pain areas of temporalis and sternocleidomastoid muscle TrPs were more inferior (lower Y-values) in adults than in children with CTTH. Conclusions.  This study showed that the Referred Pain elicited from active TrPs shared similar Pain patterns as spontaneous CTTH in adults and children. Differences in TrP prevalence and location of the Referred Pain areas can be observed between adults and children with CTTH.

  • Referred Pain from myofascial trigger points in head and neck shoulder muscles reproduces head Pain features in children with chronic tension type headache
    Journal of Headache and Pain, 2011
    Co-Authors: Cesar Fernandezdelaspenas, Daniel Martin Fernandezmayoralas, Ricardo Ortegasantiago, Silvia Ambitequesada, Domingo Palacioscena, Juan A Pareja
    Abstract:

    Our aim was to describe the Referred Pain pattern and areas from trigger points (TrPs) in head, neck, and shoulder muscles in children with chronic tension type headache (CTTH). Fifty children (14 boys, 36 girls, mean age: 8 ± 2) with CTTH and 50 age- and sex- matched children participated. Bilateral temporalis, masseter, superior oblique, upper trapezius, sternocleidomastoid, suboccipital, and levator scapula muscles were examined for TrPs by an assessor blinded to the children’s condition. TrPs were identified with palpation and considered active when local and Referred Pains reproduce headache Pain attacks. The Referred Pain areas were drawn on anatomical maps, digitalized, and also measured. The total number of TrPs was significantly greater in children with CTTH as compared to healthy children (P < 0.001). Active TrPs were only present in children with CTTH (P < 0.001). Within children with CTTH, a significant positive association between the number of active TrPs and headache duration (rs = 0.315; P = 0.026) was observed: the greater the number of active TrPs, the longer the duration of headache attack. Significant differences in Referred Pain areas between groups (P < 0.001) and muscles (P < 0.001) were found: the Referred Pain areas were larger in CTTH children (P < 0.001), and the Referred Pain area elicited by suboccipital TrPs was larger than the Referred Pain from the remaining TrPs (P < 0.001). Significant positive correlations between some headache clinical parameters and the size of the Referred Pain area were found. Our results showed that the local and Referred Pains elicited from active TrPs in head, neck and shoulder shared similar Pain pattern as spontaneous CTTH in children, supporting a relevant role of active TrPs in CTTH in children.

  • multiple active myofascial trigger points and pressure Pain sensitivity maps in the temporalis muscle are related in women with chronic tension type headache
    The Clinical Journal of Pain, 2009
    Co-Authors: Cesar Fernandezdelaspenas, Lars Arendtnielsen, Hongyou Ge, Pascal Madeleine, Ana B Caminero, A Guillemmesado, Juan A Pareja
    Abstract:

    Objective: To describe the common locations of active trigger points (TrPs) in the temporalis muscle and their Referred Pain patterns in chronic tension type headache (CTTH), and to determine if pressure sensitivity maps of this muscle can be used to describe the spatial distribution of active TrPs. Methods: Forty women with CTTH were included. An electronic pressure algometer was used to assess pressure Pain thresholds (PPT) from 9 points over each temporalis muscle: 3 points in the anterior, medial and posterior part, respectively. Both muscles were examined for the presence of active TrPs over each of the 9 points. The Referred Pain pattern of each active TrP was assessed. Results: Two-way analysis of variance detected significant differences in mean PPT levels between the measurement points (F = 30.3; P < 0.001), but not between sides (F = 2.1; P = 0.2). PPT scores decreased from the posterior to the anterior column (P < 0.001). No differences were found in the number of active TrPs (F = 0.3; P = 0.9) between the dominant side the nondominant side. Significant differences were found in the distribution of the active TrPs (x 2 = 12.2; P < 0.001): active TrPs were mostly found in the anterior column and in the middle of the muscle belly. The analysis of variance did not detect significant differences in the Referred Pain pattern between active TrPs (F = 1.1, P = 0.4). The topographical pressure Pain sensitivity maps showed the distinct distribution of the TrPs indicated by locations with low PPTs. Conclusions: Multiple active TrPs in the temporalis muscle were found, particularly in the anterior column and in the middle of the muscle belly. Bilateral posterior to anterior decreased distribution of PPTs in the temporalis muscle in women with CTTH was found. The locations of active TrPs in the temporalis muscle corresponded well to the muscle areas with lower PPT, supporting the relationship between multiple active muscle TrPs and topographical pressure sensitivity maps in the temporalis muscle in women with CTTH.

  • Referred Pain elicited by manual exploration of the lateral rectus muscle in chronic tension type headache
    Pain Medicine, 2009
    Co-Authors: Cesar Fernandezdelaspenas, Robert D Gerwin, Maria Luz Cuadrado, Juan A Pareja
    Abstract:

    Objective.  To analyze the presence of Referred Pain elicited by manual examination of the lateral rectus muscle in patients with chronic tension-type headache (CTTH). Design.  A case-control blinded study. Setting.  It has been found previously that the manual examination of the superior oblique muscle can elicit Referred Pain to the head in some patients with migraine or tension-type headache. However, a Referred Pain from other extraocular muscles has not been investigated. Methods.  Fifteen patients with CTTH and 15 healthy subjects without headache history were included. A blinded assessor performed a manual examination focused on the search for myofascial trigger points (TrPs) in the right and left lateral rectus muscles. TrP diagnosis was made when there was Referred Pain evoked by maintained pressure on the lateral corner of the orbit (anatomical projection of the lateral rectus muscle) for 20 seconds, and increased Referred Pain while the subject maintained a medial gaze on the corresponding side (active stretching of the muscle) for 15 seconds. On each side, a 10-point numerical Pain rate scale was used to assess the intensity of Referred Pain at both stages of the examination. Results.  Ten patients with CTTH (66.6%) had Referred Pain that satisfied TrPs diagnostic criteria, while only one healthy control (0.07%) reported Referred Pain upon the examination of the lateral rectus muscles (P < 0.001). The elicited Referred Pain was perceived as a deep ache located at the supraorbital region or the homolateral forehead. Pain was evoked on both sides in all subjects with TrPs, with no difference in Pain intensity between the right and the left. The average Pain intensity was significantly greater in the patient group (P < 0.001). All CTTH patients with Referred Pain recognized it as the frontal Pain that they usually experienced during their headache attacks, which was consistent with active TrPs. Conclusion.  In some patients with CTTH, the manual examination of lateral rectus muscle TrPs elicits a Referred Pain that extends to the supraorbital region or the homolateral forehead. Nociceptive inputs from the extraocular muscles may sustain the activation of trigeminal neuron, thus sensitizing central Pain pathways and exacerbating headache.

  • association of cross sectional area of the rectus capitis posterior minor muscle with active trigger points in chronic tension type headache a pilot study
    American Journal of Physical Medicine & Rehabilitation, 2008
    Co-Authors: Cesar Fernandezdelaspenas, Lars Arendtnielsen, Maria Luz Cuadrado, Juan A Pareja
    Abstract:

    Objective: To investigate whether cross-sectional area (CSA) of the suboccipital muscles was associated with active trigger points (TrPs) in chronic tension-type headache (CTTH). Design: Magnetic resonance imaging (MRI) of the cervical spine was performed in 11 females with CTTH aged from 26 to 50 yrs old. CSA for both rectus capitis posterior minor (RCPmin) and rectus capitis posterior major (RCPmaj) muscles were measured from axial T1-weighted images, using axial MRI slices aligned parallel to the C2/3 intervertebral disc. A headache diary was kept for 4 wks to record the Pain history. TrPs in the suboccipital muscle were identified by eliciting Referred Pain to palpation, and increased Referred Pain with muscle contraction. TrPs were considered active if the elicited Referred Pain reproduced the head Pain pattern and features of the pattern seen during spontaneous headache attacks. Results: Active TrPs were found in six patients (55%), whereas the remaining five patients showed latent TrPs. CSA of the RCPmin was significantly smaller (F = 13.843; P = 0.002) in the patients with active TrPs (right side: 55.9 ± 4.4 mm 2 ; left side: 61.1 ±: 3.8 mm 2 ) than in patients with latent TrPs (right side: 96.9 ± 14.4 mm 2 ; left side: 88.7 ± 9.7 mm 2 ). No significant differences were found for CSA of the RCPmaj between the patients with either active or latent TrP (P > 0.5). Conclusions: It seems that muscle atrophy in the RCPmin, but not in the RCPmaj, was associated with suboccipital active TrPs in CTTH, although studies with larger sample sizes are now required. It may be that nociceptive inputs in active TrPs could lead to muscle atrophy of the involved muscles. Muscle disuse or avoidance behavior can also be involved in atrophy.

Peter Svensson - One of the best experts on this subject based on the ideXlab platform.

  • Referred Pain and sensations evoked by standardized palpation of the masseter muscle in healthy participants
    Journal of oral and facial pain and headache, 2018
    Co-Authors: Manabu Masuda, Takashi Iida, Fernando G Exposto, Lene Baadhansen, Misao Kawara, Osamu Komiyama, Peter Svensson
    Abstract:

    Aims: To determine if standardized palpation of the masseter muscle can evoke Referred Pain and/or sensations in healthy individuals and to compare the mechanical sensitivities in response to three different levels of palpation force. Methods: A total of 32 Pain-free individuals participated. The right masseter muscle was divided into 15 test sites. Mechanical sensitivity of the masseter was assessed with three mechanical stimuli (0.5 kg, 1.0 kg, or 2.0 kg) applied by palpometers to the 15 test sites for 5 seconds each site. Participants scored the perceived intensity of Pain and unpleasantness of each of the three mechanical stimuli on 0-100 numeric rating scales (NRS). After each stimulus, the duration of aftersensation was measured, and the participants were also asked to indicate areas within the orofacial region with Referred Pain/sensations. Data were tested using analysis of variance, Tukey post hoc, and McNemar's tests with a 5% level of significance. Results: Referred Pain/sensations were most commonly evoked with the 2.0-kg stimulus (34.4% of participants; P < .05) compared to the 1.0-kg (12.5%) and 0.5-kg stimuli (3.1%). There were significant effects of stimulus intensity on NRS scores for Pain and unpleasantness, as well as for aftersensation (P < .05). There were significant effects on NRS scores for Pain and unpleasantness for the 1.0- and 2.0-kg stimuli (P < .05) and on aftersensation for the 2.0-kg stimulus (P < .05). Conclusion: These results indicate that Referred Pain/sensations in the orofacial region are frequent phenomena among healthy individuals during standardized palpation of the masseter muscle.

  • characteristics of Referred muscle Pain to the head from active trigger points in women with myofascial temporomandibular Pain and fibromyalgia syndrome
    Journal of Headache and Pain, 2012
    Co-Authors: Cristina Alonsoblanco, Cesar Fernandezdelaspenas, Peter Svensson, Fernando Galandelrio, Ana I Delallaverincon, Pedro Zarcomoreno
    Abstract:

    Our aim was to compare the differences in the prevalence and the anatomical localization of Referred Pain areas of active trigger points (TrPs) between women with myofascial temporomandibular disorder (TMD) or fibromyalgia (FMS). Twenty women (age 46 ± 8 years) with TMD and 20 (age 48 ± 6 years) with FMS were recruited from specialized clinic. Bilateral temporalis, masseter, sternocleidomastoid, upper trapezius, and suboccipital muscles were examined for TrPs. TrPs were identified by palpation and considered active when the Pain reproduced familiar Pain symptom experienced by the patient. The Referred Pain areas were drawn on anatomical maps, digitalized and also measured. A new analysis technique based on a center of gravity (COG) method was used to quantitative estimate of the localization of the TrP Referred Pain areas. Women with FMS exhibited larger areas of usual Pain symptoms than women with myofascial TMD (P < 0.001). The COG coordinates of the usual Pain on the frontal and posterior Pain maps were located more superior in TMD than in FMS. The number of active TrPs was significantly higher in TMD (mean ± SD 6 ± 1) than in FMS (4 ± 1) (P = 0.002). Women with TMD exhibited more active TrPs in the temporalis and masseter muscles than FMS (P < 0.01). Women with FMS had larger Referred Pain areas than those with TMD for sternocleidomastoid and suboccipital muscles (P < 0.001). Significant differences within COG coordinates of TrP Referred Pain areas were found in TMD, the Referred Pain was more pronounced in the orofacial region, whereas the Referred Pain in FMS was more pronounced in the cervical spine. This study showed that the Referred Pain elicited from active TrPs shared similar patterns as usual Pain symptoms in women with TMD or FMS, but that distinct differences in TrP prevalence and location of the Referred Pain areas could be observed. Differences in location of Referred Pain areas may help clinicians to determine the most relevant TrPs for each Pain syndrome in spite of overlaps in Pain areas.

  • prevalence and anatomical localization of muscle Referred Pain from active trigger points in head and neck musculature in adults and children with chronic tension type headache
    Pain Medicine, 2011
    Co-Authors: Cristina Alonsoblanco, Cesar Fernandezdelaspenas, Juan A Pareja, Peter Svensson, Daniel Martin Fernandezmayoralas, Ana I Delallaverincon
    Abstract:

    Objective.  To compare differences in the prevalence and the anatomical localization of the Referred Pain areas of active trigger points (TrPs) in head and neck musculature between adults and children with chronic tension-type headache (CTTH). Design.  A cross-sectional study. Setting.  Some studies had found that Referred Pain from active TrPs reproduce the head Pain pattern in adults. No study has compared clinical differences between Referred Pain patterns elicited by active TrPs between adults and children with CTTH. Patients.  Twenty adults (10 men, 10 women, mean age: 41 ± 11 years) and 20 children (10 boys, 10 girls, mean age: 8 ± 2 years) with CTTH were included. Outcome Measures.  Bilateral temporalis, sternocleidomastoid, upper trapezius, and suboccipital muscles were examined for TrPs. TrPs were identified by palpation and considered active when local and Referred Pains reproduce the headache Pain attacks. The Referred Pain areas were drawn on anatomical maps, digitalized, and also measured. An analysis technique based on a center of gravity (COG) method was used to provide a quantitative estimate of the localization of the TrP Referred Pain areas. Results.  Adults with CTTH exhibited a greater years with headache, higher intensity, and longer headache duration (P < 0.05) compared with children. The COG coordinates of the spontaneous Pain on the dominant side were located more anterior (higher X-value), and spontaneous Pain in the frontal and posterior areas was located more inferior (lower Y-value) in adults than in children. The number of active muscle TrPs was significantly higher (P = 0.001) in adults with CTTH (mean ± standard deviation [SD]: 4 ± 0.8) as compared with children (mean ± SD: 3 ± 0.7). Children with CTTH had larger Referred Pain areas than adults for upper trapezius, sternocleidomastoid, and temporalis (P < 0.001) muscles. The COG coordinates of the Referred Pain areas of temporalis and sternocleidomastoid muscle TrPs were more inferior (lower Y-values) in adults than in children with CTTH. Conclusions.  This study showed that the Referred Pain elicited from active TrPs shared similar Pain patterns as spontaneous CTTH in adults and children. Differences in TrP prevalence and location of the Referred Pain areas can be observed between adults and children with CTTH.

  • Referred Pain from muscle trigger points in the masticatory and neck shoulder musculature in women with temporomandibular disoders
    The Journal of Pain, 2010
    Co-Authors: Cesar Fernandezdelaspenas, Lars Arendtnielsen, Peter Svensson, Fernando Galandelrio, Cristina Alonsoblanco, Rodrigo Jimenezgarcia
    Abstract:

    Abstract Our aim was to describe the Referred Pain patterns and size of areas of trigger points (TrPs) in the masticatory and neck-shoulder muscles of women with myofascial temporomandibular disorders (TMD). Twenty-five women with myofascial TMD and 25 healthy matched women participated. Bilateral temporalis, deep masseter, superficial masseter, sternocleidomastoid, upper trapezius and suboccipital muscles were examined for TrPs by an assessor blinded to the subjects' condition. TrPs were identified with manual palpation and categorized into active and latent according to proposed criteria. The Referred Pain areas were drawn on anatomical maps, digitalized, and measured. The occurrence of active ( P P = .04) were different between groups. In all muscles, there were significantly more active and latent TrP in patients than controls ( P P P P P P P > .703). The local and Referred Pain elicited from active TrPs in the masticatory and neck-shoulder muscles shared similar Pain pattern as spontaneous TMD, which supports the concept of peripheral and central sensitization mechanisms in myofascial TMD. Perspective The current study showed the existence of multiple active muscle TrPs in the masticatory and neck-shoulder muscles in women with myofascial TMD Pain. The local and Referred Pain elicited from active TrPs reproduced Pain complaints in these patients. Further, Referred Pain areas were larger in TMD Pain patients than in healthy controls. The results are also in accordance with the notion of peripheral and central sensitization mechanisms in patients with myofascial TMD.

  • experimentally induced muscle Pain induces hypoalgesia in heterotopic deep tissues but not in homotopic deep tissues
    Brain Research, 1998
    Co-Authors: Thomas Gravennielsen, Victor Babenko, Peter Svensson, Lars Arendtnielsen
    Abstract:

    Abstract The ability of muscle Pain to generate somatosensory sensibility changes is controversial. Thus, in the present study, tonic infusion of hypertonic saline (5%, 7.1 ml administered over 15 min) into the tibialis anterior (TA) muscle was used as an experimental model to induce local and Referred Pain. The sensibility to high-intensity pressure stimuli applied to the local Pain area, Referred Pain area and an arm was assessed in 14 healthy volunteers. Infusion of isotonic (0.9%) saline into the other leg served as control. The subject continuously scored the Pain intensity on an electronic visual analogue scale (VAS). Pressure Pain threshold (PPT) was determined on the TA muscle (2 cm and 10 cm from the infusion site), at the frontal aspect of the ankle (area of Referred Pain) and on the arm. To minimise the skin component of the PPT, the skin covering the assessment sites was anaesthetised with an anaesthetic creme. The PPTs were obtained before and after cutaneous analgesia, 1 min and 10 min after infusion start and 10 min after the Pain had disappeared. Infusion of hypertonic saline caused significantly (P

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  • healthy Pain free individuals with a history of distal radius fracture demonstrate an expanded distribution of experimental Referred Pain toward the wrist
    Pain Medicine, 2020
    Co-Authors: Victor Domenechgarcia, Thorvalur S Palsson, Shellie Boudreau, Pablo Bellostalopez, Pablo Herrero, Thomas Gravennielsen
    Abstract:

    OBJECTIVE: Nociception caused by injuries may sensitize central mechanisms causing expanded Pain areas. After recovery, the status of such Pain distribution and sensitivity mechanisms is unknown. The present study investigated whether individuals who have fully recovered from a distal radius fracture demonstrate increased Pain sensitivity and expanded distribution of pressure-induced Pain. DESIGN: Cross-sectional single-blinded study. SETTING: Clinical setting. SUBJECTS: Twenty-three Pain-free individuals with a history of Painful distal radius fracture and 22 nonfractured, age/gender-matched controls participated in two experimental sessions (day 0, day 1) 24 hours apart. METHODS: Pressure Pain thresholds (PPTs) were recorded bilaterally at the extensor carpi radialis longus (ECRL), infraspinatus, and gastrocnemius muscles. Spatial distribution of Pain was assessed following 60-second Painful pressure stimulation at the ECRL (bilateral) and the infraspinatus muscles on the fractured or dominant side. Participants drew Pain areas on a body map. After day 0 assessments, prolonged Pain was induced by eccentric exercise of wrist extensors on the fractured/dominant side. RESULTS: Compared with controls, pressure-induced ECRL Pain in the fracture group Referred more frequently toward the distal forearm (P < 0.005) on day 0. Both groups showed larger Pain areas on day 1 compared with day 0 (P < 0.005), although the fracture group showed a larger relative change between days (P < 0.005). The fracture group showed larger Pain areas on the fracture side compared with the contralateral side on both days (P < 0.005). CONCLUSIONS: Prolonged Pain and recovered prior Painful injuries like fractures may sensitize Pain mechanisms manifested as expanded Pain distribution. Pressure-induced Referred Pain can be a simple Pain biomarker for clinical use.

  • reproduction of overall spontaneous Pain pattern by manual stimulation of active myofascial trigger points in fibromyalgia patients
    Arthritis Research & Therapy, 2011
    Co-Authors: Hongyou Ge, Thomas Gravennielsen, Cesar Fernandezdelaspenas, Bente Danneskioldsamsoe, Ying Wang, Lars Arendtnielsen
    Abstract:

    Introduction: It has previously been reported that local and Referred Pain from active myofascial trigger points (MTPs) in the neck and shoulder region contribute to fibromyalgia (FM) Pain and that the Pain pattern induced from active MTPs can reproduce parts of the spontaneous clinical FM Pain pattern. The current study investigated whether the overall spontaneous FM Pain pattern can be reproduced by local and Referred Pain from active MTPs located in different muscles. Methods: A spontaneous Pain pattern in FM was recorded in 30 FM patients and 30 healthy subjects served as controls. Local and Referred Pain patterns induced from active (patients) and latent (controls) MTPs were recorded following manual stimulation. The existence of MTPs was confirmed by intramuscular electromyographical registration of spontaneous electrical activity. Results: Local and Referred Pain areas induced from key active MTPs in FM were larger than Pain areas from latent MTPs in healthy controls (P 0.05). The induced Pain area was positively associated with current spontaneous Pain intensity in FM (P < 0.01). The locations of key active MTPs in FM patients were found to have latent MTPs in healthy subjects. The muscles containing key active MTPs in FM are often observed in the muscles of extensor digitorum, trapezius, infraspinatus in the upper part of the body and of quadratus lumborum, gluteus medius in the lower part of the body. Conclusions: The overall spontaneous FM Pain pattern can be reproduced by mechanical stimulation of active MTPs located in different muscles, suggesting that fibromyalgia Pain is largely composed of Pain arising from muscle Pain and spasm. Targeting active MTPs and related perpetuating factors may be an important strategy in FM Pain control. Trial registration: ISRCTN ISRCTN43167547.

  • contribution of the local and Referred Pain from active myofascial trigger points in fibromyalgia syndrome
    Pain, 2009
    Co-Authors: Hongyou Ge, Thomas Gravennielsen, Pascal Madeleine, Bente Danneskioldsamsoe, Lars Arendtnielsen
    Abstract:

    The generalized hypersensitivity associated with fibromyalgia syndrome (FMS) may in part be driven by peripheral nociceptive sources. The aim of the study was to investigate whether local and Referred Pain from active myofascial trigger points (MTrPs) contributes to fibromyalgia Pain. FMS patients and healthy controls (n = 22 each, age- and gender-matched) were recruited. The surface area over the upper trapezius muscle on each side was divided into 13 sub-areas (points) of 1 cm in diameter for each point. Pressure Pain threshold (PPT) and the local and Referred Pain pattern induced by manual palpation at 13 points bilaterally in the upper trapezius were recorded. Results showed that PPT levels at all measured points were significantly lower in FMS than controls. Multiple active MTrPs (7.4 ± 2.2) were identified bilaterally in the muscle in FMS patients, but no active MTrPs were found in controls. The mid-fiber region of the muscle had the lowest PPT level with the largest number of active MTrPs in FMS and with the largest number of latent MTrPs in controls. The local and Referred Pain pattern induced from active MTrPs bilaterally in the upper trapezius muscle were similar to the ongoing Pain pattern in the neck and shoulder region in FMS. In conclusion, active MTrPs bilaterally in the upper trapezius muscle contribute to the neck and shoulder Pain in FMS. Active MTrPs may serve as one of the sources of noxious input leading to the sensitization of spinal and supraspinal Pain pathways in FMS.

  • sensory and motor effects of experimental muscle Pain in patients with lateral epicondylalgia and controls with delayed onset muscle soreness
    Pain, 2005
    Co-Authors: Helen Slater, Lars Arendtnielsen, Anthony Wright, Thomas Gravennielsen
    Abstract:

    This study compares the effect of experimental muscle Pain on deep tissue sensitivity and force attenuation in the wrist extensors of patients with lateral epicondylalgia (n=20), and healthy controls (n=20) with experimentally induced sensori-motor characteristics simulating lateral epicondylalgia. Delayed onset muscle soreness (DOMS) in wrist extensors of healthy controls was induced by eccentric exercise in one arm 24 h prior to injection (Day 0). Saline-induced Pain intensity (visual analogue scale, VAS), distribution, and quality were assessed quantitatively in both arms for both groups. Pressure Pain thresholds (PPT) were assessed at three different sites in the wrist extensors. Maximal grip force and wrist extension force were recorded. In response to saline-induced Pain in the extensor carpi radialis brevis, regardless of arm, the patient group demonstrated a significantly quicker Pain onset (P<0.01), mapped larger Pain areas and more Referred Pain areas, compared to healthy controls (P<0.03). Pain persisted significantly longer in the sore arm of the patient group, compared with all other arms (P<0.02). Patients demonstrated significant bilateral hyperalgesia at extensor carpi radialis brevis during and post saline-induced Pain compared to pre-injection and healthy controls (P<0.04). The sore arm in patients and the DOMS arms in healthy subjects showed significantly reduced maximal force (P<0.0001), at all Day 1 times compared with the control arms. In patients, the bilateral increase in deep tissue sensitivity and enlarged Referred Pain areas during saline-induced Pain might suggest involvement of central sensitisation.

  • opioid insensitive hypoalgesia to mechanical stimuli at sites ipsilateral and contralateral to experimental muscle Pain in human volunteers
    Experimental Brain Research, 2002
    Co-Authors: Thomas Gravennielsen, Stephen J Gibson, Rene Johannes Laursen, Lars Arendtnielsen
    Abstract:

    Musculoskeletal Pains are often characterised by Referred Pain and hyperalgesia. The aim of the present study was to examine the sensitivity to pressure and pinprick at sites ipsi- and contralateral to capsaicin-induced Pain in the tibialis anterior (TA) muscle. Visual analogue scale (VAS) scores of the sensation to sub- and supra-Pain threshold stimuli by pressure and pinprick were recorded before, during and after experimental muscle Pain. It was found that pressure stimulation (120% of baseline Pain threshold) delivered over the ipsilateral deep peroneal nerve between the 1st and 2nd metatarsal bones showed a significant increase in VAS scores during muscle Pain. The Referred Pain did not overlap this hyperalgesic site. Ipsilateral test sites at the TA muscle, great toe and between the 3rd and 4th metatarsal bones did not show any changes in response to pressure stimulation during Pain. In contrast, test sites at the ipsilateral ankle showed hypoalgesia to pressure during muscle Pain. In the contralateral leg hypoalgesia to pressure was found at all sites during Pain. The decreased sensitivity to pressure was confirmed with both sub- and supra-pressure Pain-threshold stimuli. VAS scores to pinprick were either decreased or unchanged during Pain compared to before Pain. Naloxone administrated in a placebo-controlled manner had no effect on hypoalgesia to pressure or pinprick during muscle Pain. Thus, the generalised decreased sensitivity may reflect activation of non-opioid endogenous Pain inhibitory systems. The lack of change in sensitivity at some sites could indicate a competitive balance between excitatory and inhibitory mechanisms. The deep peroneal nerve specifically innervates both the TA muscle and the only site of hyperalgesia indicating spatial summation of afferent activity from these structures.