1
|
Abrahamsen R, Naish P. Studies in patients with temporomandibular disorders pain: Can scales of hypnotic susceptibility predict the outcome on pain relief? AMERICAN JOURNAL OF CLINICAL HYPNOSIS 2022; 64:12-19. [PMID: 34748465 DOI: 10.1080/00029157.2020.1863183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Many medical conditions are claimed to benefit when hypnosis is incorporated into their treatment. For some conditions, the claims are largely anecdotal, but the treatment of pain stands out in two ways. First, there is a strong body of evidence that hypnosis can produce clinically useful analgesic effects. Second, since innocuous pain can be induced in the laboratory, the process can be explored rigorously. This idea assumes that experimentally induced pain and clinical pain behave identically. We describe using experimentally induced pain in patients already suffering from temporomandibular disorders. Scanning results indicate that the pain and its amelioration are the same in the two circumstances. Moreover, the absence of any impact upon a nociceptive trigemino-facial reflex implies that the impact of hypnosis is purely cortical. Finally, we address the observation that clinical success correlates poorly with hypnotic susceptibility scores. It is proposed that a painful experimental situation induces anxiety. This, like hypnosis, has been associated with an emphasis on right hemisphere activity. Thus, clinical anxiety may render a person more responsive to hypnosis than would be indicated by a susceptibility test delivered in stress-free circumstances.
Collapse
|
2
|
Khodashenas M, Baghdadi G, Towhidkhah F. A modified Hodgkin-Huxley model to show the effect of motor cortex stimulation on the trigeminal neuralgia network. JOURNAL OF MATHEMATICAL NEUROSCIENCE 2019; 9:4. [PMID: 31152270 PMCID: PMC6544710 DOI: 10.1186/s13408-019-0072-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 05/21/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Trigeminal neuralgia (TN) is a severe neuropathic pain, which has an electric shock-like characteristic. There are some common treatments for this pain such as medicine, microvascular decompression or radio frequency. In this regard, transcranial direct current stimulation (tDCS) is another therapeutic method to reduce pain, which has been recently attracting the therapists' attention. The positive effect of tDCS on TN was shown in many previous studies. However, the mechanism of the tDCS effect has remained unclear. OBJECTIVE This study aims to model the neuronal behavior of the main known regions of the brain participating in TN pathways to study the effect of transcranial direct current stimulation. METHOD The proposed model consists of several blocks: (1) trigeminal nerve, (2) trigeminal ganglion, (3) PAG (periaqueductal gray in the brainstem), (4) thalamus, (5) motor cortex (M1) and (6) somatosensory cortex (S1). Each of these components is represented by a modified Hodgkin-Huxley (HH) model. The modification of the HH model was done based on some neurological facts of pain sodium channels. The input of the model involves any stimuli to the 'trigeminal nerve,' which cause the pain, and the output is the activity of the somatosensory cortex. An external current, which is considered as an electrical current, was applied to the motor cortex block of the model. RESULT The results showed that by decreasing the conductivity of the slow sodium channels (pain channels) and applying tDCS over the M1, the activity of the somatosensory cortex would be reduced. This reduction can cause pain relief. CONCLUSION The proposed model provided some possible suggestions about the relationship between the effects of tDCS and associated components in TN, and also the relationship between the pain measurement index, somatosensory cortex activity, and the strength of tDCS.
Collapse
Affiliation(s)
| | - Golnaz Baghdadi
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Farzad Towhidkhah
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| |
Collapse
|
3
|
de Tommaso M, Delussi M. Nociceptive blink reflex habituation biofeedback in migraine. FUNCTIONAL NEUROLOGY 2018; 32:123-130. [PMID: 29042000 DOI: 10.11138/fneur/2017.32.3.123] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Reduced habituation of the nociceptive blink reflex (NBR) is considered a trait marker for genetic predisposition to migraine. In this open-label randomized controlled study, we aimed to test the efficacy of a biofeedback training based on learning of habituation of the NBR (NBR biofeedback) compared with pharmacological (topiramate) treatment and NBR biofeedback plus topiramate treatment in a cohort of migraine without aura patients eligible for prophylaxis. Thirty-three migraine patients were randomly assigned to three months of treatment with: 1) NBR biofeedback, 2) NBR biofeedback plus topiramate 50 mg (b.i.d.), or 3) topiramate 50 mg (b.i.d.). Frequency of headache and disability changes were the main study outcomes. Anxiety, depression, sleep, fatigue, quality of life, allodynia and pericranial tenderness were also evaluated. NBR biofeedback reduced the R2 area, without improving R2 habituation. However, it reduced the frequency of headache and disability, similarly to the combined treatment and topiramate alone. Reduced habituation of the NBR is a stable neurophysiological pattern, scarcely modifiable by learning procedures. Training methods able to act on stress-related responses may modulate cortical mechanisms inducing migraine onset and trigeminal activation under stressful trigger factors.
Collapse
|
4
|
Reindl C, Seifert F, Nickel F, Maihöfner C. Neuromodulation of Electrically Induced Hyperalgesia in the Trigeminocervical System. Pain Pract 2015; 16:712-9. [PMID: 26017620 DOI: 10.1111/papr.12320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 04/07/2015] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Trigeminal and cervical afferents converge on neurons of the trigeminocervical complex and may significantly alter the function of these neurons. This interaction may have implications for the pathophysiology and treatment of primary headache disorders. Therefore, the aim of this work was to study pain modulatory mechanisms within the trigeminocervical complex. SUBJECTS We used an electrical pain model challenging pro- and antinociceptive systems in 19 healthy volunteers. METHODS Transcutaneous supraorbital noxious electrical low-frequency stimulation (0.5 Hz), known to induce both hyperalgesia due to central sensitization (as a marker of pain facilitation) and habituation (as a marker of pain inhibition), was combined with different noxious stimulation paradigms applied to the innervation territory of upper cervical afferents. We investigated the effects of concurrent stimulation in the cervical/extratrigeminal system on habituation profiles, hyperalgesic area, pain, and detection thresholds in the trigeminal system. RESULTS It was previously shown that conditioning 20-Hz noxious electrical stimuli may provoke centrally mediated sensory decline that possesses heterotopic antihyperalgesic properties. Occipital and forearm costimulation at a frequency of 20 Hz had no significant modulating effect on supraorbital pain adaptation, hyperalgesic area, or pain perception. Effects for trigeminal stimulation were independent of occipital stimulus intensity. Furthermore, for single occipital stimulation at 0.5 and 20 Hz, no somatosensory changes could be demonstrated within the trigeminal system. CONCLUSION Trigeminal nociception stayed unchanged despite of occipital costimulation.
Collapse
Affiliation(s)
- Caroline Reindl
- Department of Neurology, University Hospital of Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Frank Seifert
- Department of Neurology, University Hospital of Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Florian Nickel
- Department of Neurology, University Hospital of Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.,Department of Neurology, Fürth General Hospital, Fürth, Germany
| | - Christian Maihöfner
- Department of Neurology, University Hospital of Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.,Department of Neurology, Fürth General Hospital, Fürth, Germany
| |
Collapse
|
5
|
Racine M, Tousignant-Laflamme Y, Kloda LA, Dion D, Dupuis G, Choinière M. A systematic literature review of 10 years of research on sex/gender and experimental pain perception - part 1: are there really differences between women and men? Pain 2012; 153:602-618. [PMID: 22192712 DOI: 10.1016/j.pain.2011.11.025] [Citation(s) in RCA: 437] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 11/15/2011] [Accepted: 11/22/2011] [Indexed: 01/08/2023]
Abstract
The purpose of this systematic review was to summarize and critically appraise the results of 10 years of human laboratory research on pain and sex/gender. An electronic search strategy was designed by a medical librarian and conducted in multiple databases. A total of 172 articles published between 1998 and 2008 were retrieved, analyzed, and synthesized. The first set of results (122 articles), which is presented in this paper, examined sex difference in the perception of laboratory-induced thermal, pressure, ischemic, muscle, electrical, chemical, and visceral pain in healthy subjects. This review suggests that females (F) and males (M) have comparable thresholds for cold and ischemic pain, while pressure pain thresholds are lower in F than M. There is strong evidence that F tolerate less thermal (heat, cold) and pressure pain than M but it is not the case for tolerance to ischemic pain, which is comparable in both sexes. The majority of the studies that measured pain intensity and unpleasantness showed no sex difference in many pain modalities. In summary, 10 years of laboratory research have not been successful in producing a clear and consistent pattern of sex differences in human pain sensitivity, even with the use of deep, tonic, long-lasting stimuli, which are known to better mimic clinical pain. Whether laboratory studies in healthy subjects are the best paradigm to investigate sex differences in pain perception is open to question and should be discussed with a view to enhancing the clinical relevance of these experiments and developing new research avenues.
Collapse
Affiliation(s)
- Mélanie Racine
- Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada École de réadaptation, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada Life Sciences Library, McGill University, Montreal, Quebec, Canada Department of Family Medicine and Emergency, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada Research Centre, Montreal Heart Institute, Montreal, Quebec, Canada Department of Anaesthesiology, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | | | | | | | | | | |
Collapse
|
6
|
de Tommaso M, Santostasi R, Devitofrancesco V, Franco G, Vecchio E, Delussi M, Livrea P, Katzarava Z. A comparative study of cortical responses evoked by transcutaneous electrical vs CO2 laser stimulation. Clin Neurophysiol 2011; 122:2482-7. [DOI: 10.1016/j.clinph.2011.05.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 05/03/2011] [Accepted: 05/05/2011] [Indexed: 11/16/2022]
|
7
|
Dong Y, Li J, Zhang F, Li Y. Nociceptive afferents to the premotor neurons that send axons simultaneously to the facial and hypoglossal motoneurons by means of axon collaterals. PLoS One 2011; 6:e25615. [PMID: 21980505 PMCID: PMC3183065 DOI: 10.1371/journal.pone.0025615] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 09/07/2011] [Indexed: 11/19/2022] Open
Abstract
It is well known that the brainstem premotor neurons of the facial nucleus and hypoglossal nucleus coordinate orofacial nociceptive reflex (ONR) responses. However, whether the brainstem PNs receive the nociceptive projection directly from the caudal spinal trigeminal nucleus is still kept unclear. Our present study focuses on the distribution of premotor neurons in the ONR pathways of rats and the collateral projection of the premotor neurons which are involved in the brainstem local pathways of the orofacial nociceptive reflexes of rat. Retrograde tracer Fluoro-gold (FG) or FG/tetramethylrhodamine-dextran amine (TMR-DA) were injected into the VII or/and XII, and anterograde tracer biotinylated dextran amine (BDA) was injected into the caudal spinal trigeminal nucleus (Vc). The tracing studies indicated that FG-labeled neurons receiving BDA-labeled fibers from the Vc were mainly distributed bilaterally in the parvicellular reticular formation (PCRt), dorsal and ventral medullary reticular formation (MdD, MdV), supratrigeminal nucleus (Vsup) and parabrachial nucleus (PBN) with an ipsilateral dominance. Some FG/TMR-DA double-labeled premotor neurons, which were observed bilaterally in the PCRt, MdD, dorsal part of the MdV, peri-motor nucleus regions, contacted with BDA-labeled axonal terminals and expressed c-fos protein-like immunoreactivity which induced by subcutaneous injection of formalin into the lip. After retrograde tracer wheat germ agglutinated horseradish peroxidase (WGA-HRP) was injected into VII or XII and BDA into Vc, electron microscopic study revealed that some BDA-labeled axonal terminals made mainly asymmetric synapses on the dendritic and somatic profiles of WGA-HRP-labeled premotor neurons. These data indicate that some premotor neurons could integrate the orofacial nociceptive input from the Vc and transfer these signals simultaneously to different brainstem motonuclei by axonal collaterals.
Collapse
Affiliation(s)
- Yulin Dong
- Department of Anatomy and Histology and Embryology, and K. K. Leung Brain Research Centre, the Fourth Military Medical University, Xi'an, China
| | - Jinlian Li
- Department of Anatomy and Histology and Embryology, and K. K. Leung Brain Research Centre, the Fourth Military Medical University, Xi'an, China
- * E-mail: (JL); (YL)
| | - Fuxing Zhang
- Department of Anatomy and Histology and Embryology, and K. K. Leung Brain Research Centre, the Fourth Military Medical University, Xi'an, China
| | - Yunqing Li
- Department of Anatomy and Histology and Embryology, and K. K. Leung Brain Research Centre, the Fourth Military Medical University, Xi'an, China
- * E-mail: (JL); (YL)
| |
Collapse
|
8
|
Impaired somatosensation in tongue mucosa of smokers. Clin Oral Investig 2010; 16:39-44. [PMID: 20938792 DOI: 10.1007/s00784-010-0480-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 09/28/2010] [Indexed: 10/19/2022]
Abstract
Smoking has been indicated as a risk factor for oral diseases and can lead to altered sense of taste. So far, the effects of sensory changes on the tongue are not investigated. In this study, quantitative sensory testing was used to evaluate somatosensory function in the lingual region. Eighty healthy volunteers were investigated (20 smokers, 20 non-smokers). Subjects were bilaterally tested in innervation areas of lingual nerves. Thresholds of cold and warm detection, cold and heat pain, and mechanical detection were determined. As control for systemic, extraoral effects of smoking, tests were additionally performed in 40 volunteers (20 smokers, 20 non-smokers) on the skin of the chin innervated by the mental branch of the trigeminal nerve. Cold (p < 0.001), warm detection thresholds (p < 0.001), and thermal sensory limen (p < 0.001) showed higher sensitivity in non-smokers as compared to smokers. Heat pain and mechanical detection, as well as all tests in the skin of the chin, showed no significant differences. The impaired temperature perception in smokers indicates a reduction of somatosensory functions in the tongue, possibly caused by nerve degeneration associated with smoking. Possible systemic effects of smoking do not seem to affect extraoral trigeminal branches.
Collapse
|
9
|
Yekta SS, Smeets R, Stein JM, Ellrich J. Assessment of trigeminal nerve functions by quantitative sensory testing in patients and healthy volunteers. J Oral Maxillofac Surg 2010; 68:2437-51. [PMID: 20598414 DOI: 10.1016/j.joms.2009.12.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 12/21/2009] [Accepted: 12/21/2009] [Indexed: 10/19/2022]
Abstract
PURPOSE Orofacial sensory dysfunction plays an important role in oral and maxillofacial surgery. Quantitative sensory testing (QST) is a psychophysical approach to evaluate thermal and mechanical somatosensation. PATIENTS AND METHODS The present human study 1) collected normative QST data in extraoral and intraoral regions, 2) analyzed effects of age, gender, and anatomical sites on QST, and 3) applied QST in 11 patients with iatrogenic inferior alveolar nerve lesions. Sixty (30 male and 30 female) healthy volunteers were tested bilaterally in the innervation areas of infraorbital, mental, and lingual nerves. Ten patients with sensory disturbances in innervation areas of the mental nerve were investigated at 1, 4, and 8 weeks after surgery. Another patient with a complete sensory loss after surgery was repetitively tested within 453 days after primary surgery (dental implant) and subsequent surgical reconstruction of the inferior alveolar nerve by autologous graft. RESULTS Older subjects were significantly less sensitive than younger subjects for thermal parameters. Thermal detection thresholds in infraorbital and mental regions showed higher sensitivity in women. Sensitivity to thermal stimulation was higher in the infraorbital region than in the mental and lingual regions. QST monitored somatosensory deficits and recovery of inferior alveolar nerve functions in all patients. CONCLUSIONS Age, gender, and anatomic region affect various QST parameters. QST might be useful in the diagnosis of inferior alveolar nerve disorders in patients. In dentistry, the monitoring of afferent nerve fiber functions by QST might support decisions on further interventions.
Collapse
Affiliation(s)
- Sareh Said Yekta
- Department of Conservative Dentistry, Periodontology and Preventive Dentistry, Aachen University, Aachen, Germany
| | | | | | | |
Collapse
|
10
|
Aymanns M, Yekta SS, Ellrich J. Homotopic long-term depression of trigeminal pain and blink reflex within one side of the human face. Clin Neurophysiol 2009; 120:2093-2099. [DOI: 10.1016/j.clinph.2009.08.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 08/17/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
|
11
|
de Tommaso M, Sardaro M, Pecoraro C, Di Fruscolo O, Serpino C, Lamberti P, Livrea P. Effects of the remote C fibres stimulation induced by capsaicin on the blink reflex in chronic migraine. Cephalalgia 2007; 27:881-90. [PMID: 17593297 DOI: 10.1111/j.1468-2982.2007.01357.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The aim of this study was to test the function of the diffuse noxious inhibitory control system (DNIC) in chronic and episodic migraine, exploring the blink reflex (BR) modifications induced by topical application of capsaicin on the hand. We evaluated 11 migraine without aura (MA) and nine chronic migraine (CM) patients during the not symptomatic phase; they were compared with 14 non-headache subjects (N). The BR was elicited by weak electrical stimuli delivered to the right supraorbital nerve; it was obtained 10 min and 20 min after the application of 1 ml of 3% capsaicin in a cream base (Teofarma) on the skin of the dorsum of the right hand, and 60 min after capsaicin removal. The subjective pain sensation induced by capsaicin was significantly increased in CM with respect to both MA patients and normal subjects; the R2 area was increased in CM patients during capsaicin application, with respect to controls and MA patients, who did not exhibit any reflex alterations. These results may suggest a failure of DNIC and a disturbed control of the trigeminal reflex at the central level, linked with migraine frequency.
Collapse
Affiliation(s)
- M de Tommaso
- TIRES (Centre of Innnovative Technologies for Signal Detection and Processing), Bari, Italy.
| | | | | | | | | | | | | |
Collapse
|
12
|
Ellrich J, Ristic D, Yekta SS. Impaired thermal perception in cluster headache. J Neurol 2006; 253:1292-9. [PMID: 16649093 DOI: 10.1007/s00415-006-0208-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Accepted: 02/23/2006] [Indexed: 11/30/2022]
Abstract
Cluster headache is characterized by attacks of severe periorbital pain. Repetitive burst activity in afferent fibers may induce plastic alterations in somatosensory synaptic processing as a prerequisite for recurring and chronic pain. This psychophysical study addressed hypothesized dysfunctions in craniofacial somatosensory processing in cluster headache disease. Thermal and mechanical sensory functions in the periorbital region were assessed by quantitative sensory testing (QST) in 25 cluster headache patients and 60 healthy volunteers. Perception of warmth (p<0.01), cold (p<0.000001), and pressure pain (p<0.05) was reduced on the cluster side as compared with the contralateral asymptomatic side. In contrast to healthy volunteers, warm detection threshold (WDT) and thermal sensory limen (TSL) on one side did not positively correlate with the other side. WDT and TSL negatively correlated with the elapsed time since last attack. All patients showed QST abnormalities on the headache side in comparison to healthy controls. Loss of sensory functions strongly preponderated gain. Several lines of evidence indicate a pivotal role of the hypothalamus in cluster headache pathophysiology. The impairment of warm and cold perception in patients may be based upon a dysfunction of the hypothalamus which is strongly involved in thermosensory control.
Collapse
Affiliation(s)
- Jens Ellrich
- Department of Neurosurgery, Experimental Neurosurgery Section, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.
| | | | | |
Collapse
|
13
|
Cruccu G, Iannetti GD, Truini A. Chapter 28 Brainstem reflexes and their relevance to pain. HANDBOOK OF CLINICAL NEUROLOGY 2006; 81:411-IX. [PMID: 18808850 DOI: 10.1016/s0072-9752(06)80032-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
14
|
Cruccu G, Biasiotta A, Galeotti F, Iannetti GD, Innocenti P, Romaniello A, Truini A. Chapter 14 Diagnosis of trigeminal neuralgia: a new appraisal based on clinical and neurophysiological findings. ACTA ACUST UNITED AC 2006; 58:171-86. [PMID: 16623330 DOI: 10.1016/s1567-424x(09)70067-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- G Cruccu
- Department of Neurological Sciences, "La Sapienza" University, 00185 Rome, Italy.
| | | | | | | | | | | | | |
Collapse
|
15
|
Yekta SS, Lamp S, Ellrich J. Heterosynaptic long-term depression of craniofacial nociception: divergent effects on pain perception and blink reflex in man. Exp Brain Res 2005; 170:414-22. [PMID: 16328263 DOI: 10.1007/s00221-005-0226-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 09/08/2005] [Indexed: 10/25/2022]
Abstract
Noxious low-frequency stimulation (LFS) of presynaptic nerve fibers induces long-term depression (LTD) of synaptic transmission. In vitro studies suggest a sole homosynaptic effect. Consequently, the present study addressed the hypothesis that LTD of craniofacial nociception in man is mediated by a homosynaptic mechanism. Nociceptive supraorbital afferents were excited by electric pulses via a concentric electrode in ten healthy volunteers. The electrically evoked bilateral blink reflex (BR) was recorded from both orbicularis oculi muscles by surface electrodes. The BR was evoked in blocks of ten electric stimuli each (0.1 Hz) with an interblock interval of 8 min. Conditioning noxious LFS (1 Hz, 20 min) was applied via concentric electrode either to the same site as BR test stimuli (ipsilateral) or to the corresponding contralateral forehead area (contralateral). LFS and test stimulus intensities corresponded to about threefold the pain threshold. After three baseline stimulus blocks, either conditioning ipsilateral or contralateral LFS were applied or stimulation was interrupted for 20 min as a control task. Afterwards, test stimulation blocks were continued for 40 min. Each volunteer participated in all three sessions on different days. Noxious LFS induced LTD of the BR independently from the side of conditioning stimulation. Pain perception decreased after ipsilateral LFS but not after contralateral LFS. The bilateral effect of noxious LFS on the BR provides evidence for heterosynaptic LTD based on bilateral projections of supraorbital nerve afferents onto spinal trigeminal nuclei. The divergent effect on pain perception may be due to a preferential contralateral projection of nociceptive afferents onto reflex interneurons but not onto trigeminothalamic projection neurons.
Collapse
Affiliation(s)
- Sareh Said Yekta
- Department of Neurosurgery, Experimental Neurosurgery Section, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | | | | |
Collapse
|
16
|
Abstract
The majority of the studies on laser evoked potentials (LEPs) have been focused on hand and foot stimulations and only lately on the trigeminal system. Because of a high receptor density in the facial skin and the very short conduction distance, LEP recordings after trigeminal stimulation are easier and quicker than those after stimulation of the limb extremities. Laser pulses with a stimulus intensity close to perception threshold can evoke well-defined LEPs. Few trials are sufficient to yield stable and reproducible averages. Even ultralate LEPs related to the C-fibre input are comparatively easily obtained from the trigeminal territory. The brain generators of the main LEP waves are probably very close for the trigeminal and limb stimulations. Trigeminal LEPs have been found absent or delayed in patients with trigeminal neuralgia, trigeminal neuropathies, posterior fossa tumors, and brainstem infarctions or demyelinating plaques. Conversely, trigeminal LEPs appear to be enhanced in patients with migraine. High-intensity pulses directed to any trigeminal division also elicit reflex responses: a blink-like reflex in the orbicularis oculi and a single silent period in the contracting masseter muscle. The availability of a neurophysiological method of assessing function of the trigeminal nociceptive pathways reaching both the cerebral cortex and the brainstem reflex circuits, has provided new opportunities for investigating the pathophysiology of orofacial pain syndromes.
Collapse
Affiliation(s)
- A Romaniello
- Department of Neurological Sciences, University La Sapienza, Viale Università 30, 00185 Rome, Italy
| | | | | | | |
Collapse
|