scholarly journals Does Dexmedetomidine Have a Perineural Mechanism of Action When Used as an Adjuvant to Ropivacaine?

2017 ◽  
Vol 126 (1) ◽  
pp. 66-73 ◽  
Author(s):  
Jakob H. Andersen ◽  
Ulrik Grevstad ◽  
Hanna Siegel ◽  
Jørgen B. Dahl ◽  
Ole Mathiesen ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Outcome Measure ◽  
Detection Threshold ◽  
Saphenous Nerve ◽  
Heat Pain ◽  
Nerve Blocks ◽  
Heat Stimulation ◽  
Temperature Sensation ◽  
Peripheral Mechanism ◽  
Pain Detection

Abstract Background Dexmedetomidine used as an adjuvant to local anesthetics may prolong the duration of peripheral nerve blocks. Whether this is mediated by a perineural or systemic mechanism remains unknown. The authors hypothesized that dexmedetomidine has a peripheral mechanism of action. Methods The authors conducted a randomized, paired, triple-blind trial in healthy volunteers. All received bilateral saphenous nerve blocks with 20 ml ropivacaine, 0.5%, plus 1 ml dexmedetomidine, 100 µg/ml, in one thigh and 20 ml ropivacaine 0.5% plus 1 ml saline in the other thigh. The primary outcome measure was the duration of block assessed by temperature sensation (alcohol swab). The secondary outcome measure was the duration of block assessed by pinprick, pain during tonic heat stimulation, warmth detection threshold, and heat pain detection threshold. Results All 21 enrolled volunteers completed the trial. The mean duration of block assessed by temperature sensation in the leg receiving ropivacaine plus dexmedetomidine was 22 h (95% CI, 21 to 24) compared to 20 h (95% CI, 19 to 21) in the leg receiving ropivacaine plus placebo with a mean difference of 2 h (95% CI, 1 to 3; P = 0.001). The duration of block was also significantly longer in the leg receiving dexmedetomidine when assessed by pinprick, pain during tonic heat stimulation, and warmth detection threshold but not heat pain detection threshold. One participant experienced numbness in an area in the leg receiving dexmedetomidine. Conclusions Dexmedetomidine prolongs the duration of a saphenous nerve block by a peripheral mechanism when controlling for systemic effects but not necessarily to a clinically relevant extent.

scholarly journals Heat pain detection threshold is associated with the area of secondary hyperalgesia following brief thermal sensitization: a study of healthy male volunteers [Corrigendum]

2017 ◽  
Vol Volume 10 ◽  
pp. 1135-1136
Author(s):  
Morten Sejer Hansen ◽  
Jørn Wetterslev ◽  
Christian Bressen Pipper ◽  
Mohammad Sohail Asghar ◽  
Jørgen Berg Dahl
Keyword(s):  
Detection Threshold ◽  
Heat Pain ◽  
Secondary Hyperalgesia ◽  
Healthy Male ◽  
Healthy Male Volunteers ◽  
Male Volunteers ◽  
Thermal Sensitization ◽  
Pain Detection

scholarly journals Heat pain detection threshold is associated with the area of secondary hyperalgesia following brief thermal sensitization: a study of healthy male volunteers

2017 ◽  
Vol Volume 10 ◽  
pp. 265-274 ◽  
Author(s):  
Morten Sejer Hansen ◽  
Jørn Wetterslev ◽  
Christian Bressen Pipper ◽  
Mohammad Sohail Asghar ◽  
Jørgen Berg Dahl
Keyword(s):  
Detection Threshold ◽  
Heat Pain ◽  
Secondary Hyperalgesia ◽  
Healthy Male ◽  
Healthy Male Volunteers ◽  
Male Volunteers ◽  
Thermal Sensitization ◽  
Pain Detection

Effects of perineural administration of ropivacaine combined with perineural or intravenous administration of dexmedetomidine for sciatic and saphenous nerve blocks in dogs

2021 ◽  
Vol 82 (6) ◽  
pp. 449-458
Author(s):  
Vincent Marolf ◽  
Keila K. Ida ◽  
Danuta Siluk ◽  
Wiktoria Struck-Lewicka ◽  
Michał J. Markuszewski ◽  
...  
Keyword(s):  
Intravenous Administration ◽  
Saphenous Nerve ◽  
Nerve Blocks

High-frequency submaximal stimulation over muscle evokes centrally generated forces in human upper limb skeletal muscles

2009 ◽  
Vol 106 (2) ◽  
pp. 370-377 ◽  
Author(s):  
Jean-Sébastien Blouin ◽  
Lee D. Walsh ◽  
Peter Nickolls ◽  
Simon C. Gandevia
Keyword(s):  
Upper Limb ◽  
High Frequency ◽  
Biceps Brachii ◽  
Fine Motor ◽  
Nerve Blocks ◽  
Ia Afferents ◽  
Lower Limb Muscles ◽  
Peripheral Mechanism ◽  
Central Origin ◽  
Motor Activities

Control of posture and movement requires control of the output from motoneurons. Motoneurons of human lower limb muscles exhibit sustained, submaximal activity to high-frequency electrical trains, which has been hypothesized to be partly triggered by monosynaptic Ia afferents. The possibility to trigger such behavior in upper limb motoneurons and the potential unique role of Ia afferents to trigger such behavior remain unclear. Subjects ( n = 9) received high-frequency trains of electrical stimuli over biceps brachii and flexor pollicis longus (FPL). We chose to study the FPL muscle because it has weak monosynaptic Ia afferent connectivity and it is involved in fine motor control of the thumb. Two types of stimulus trains (100-Hz bursts and triangular ramps) were tested at five intensities below painful levels. All subjects exhibited enhanced torque in biceps and FPL muscles after both types of high-frequency train. Torques also persisted after stimulation, particularly for the highest stimulus intensity. To separate the evoked torques that resulted from a peripheral mechanism (e.g., muscle potentiation) and that which resulted from a central origin, we studied FPL responses to high-frequency trains after complete combined nerve blocks of the median and radial nerves ( n = 2). During the blocks, high-frequency trains over the FPL did not yield torque enhancements or persisting torques. These results suggest that enhanced contractions of central origin can be elicited in motoneurons innervating the upper limb, despite weak monosynaptic Ia connections for FPL. Their presence in a recently evolved human muscle (FPL) indicates that these enhanced contractions may have a broad role in controlling tonic postural outputs of hand muscles and that they may be available even for fine motor activities involving the thumb.

scholarly journals Ejaculatory Pain

2007 ◽  
Vol 107 (2) ◽  
pp. 298-304 ◽  
Author(s):  
Eske K. Aasvang ◽  
Bo Møhl ◽  
Henrik Kehlet
Keyword(s):  
Chronic Pain ◽  
Sexual Dysfunction ◽  
Quantitative Sensory Testing ◽  
Groin Hernia ◽  
Pain Treatment ◽  
Detection Threshold ◽  
Control Group ◽  
Sensory Testing ◽  
Detection Thresholds ◽  
Pain Detection

Background Sexual dysfunction due to ejaculatory and genital pain after groin hernia surgery may occur in approximately 2.5% of patients. However, the specific psychosexological and neurophysiologic characteristics have not been described, thereby precluding assessment of pathogenic mechanisms and treatment strategies. Methods Ten patients with severe pain-related sexual dysfunction and ejaculatory pain were assessed in detail by quantitative sensory testing and interviewed by a psychologist specialized in evaluating sexual functional disorders and were compared with a control group of 20 patients with chronic pain after groin hernia repair but without sexual dysfunction, to identify sensory changes associated with ejaculatory pain. Results Quantitative sensory testing showed significantly higher thermal and mechanical detection thresholds and lowered mechanical pain detection thresholds in both groups compared with the nonpainful side. Pressure pain detection threshold and tolerance were significantly lower in the ejaculatory pain group compared with the control group. 'The maximum pain was specifically located at the external inguinal annulus in all ejaculatory pain patients, but not in controls. The psychosexual interview revealed no major psychosexual disturbances and concluded that the pain was of somatic origin. All patients with ejaculatory pain had experienced major negative life changes and deterioration in their overall quality of life and sexual function as a result of the hernia operation. Conclusions Postherniotomy ejaculatory pain and pain-related sexual dysfunction is a specific chronic pain state that may be caused by pathology involving the vas deferens and/or nerve damage. Therapeutic strategies should therefore include neuropathic pain treatment and/or surgical exploration.

scholarly journals Nerve Blocks around the Knee in Children

1984 ◽  
Vol 12 (1) ◽  
pp. 14-17 ◽  
Author(s):  
P. M. Kempthorne ◽  
T. C. K. Brown
Keyword(s):  
Tibial Nerve ◽  
Common Peroneal Nerve ◽  
Saphenous Nerve ◽  
Popliteal Fossa ◽  
Nerve Stimulator ◽  
Nerve Blocks ◽  
Peripheral Nerve Stimulator ◽  
Below The Knee ◽  
The Common ◽  
Equinus Deformity

Analgesia below the knee can be achieved by blocking the tibial nerve and the common peroneal nerve in the popliteal fossa, and the saphenous nerve adjacent to the knee. The anatomy and technique of nerve block in the popliteal fossa is described, the nerve being located prior to blockade using a peripheral nerve stimulator. The block as described has been used in children for postoperative analgesia, as a diagnostic block, and as an adjunct to the physiotherapy management of severe equinus deformity after brain injury.

Refining a great idea: the consolidation of PECS I, PECS II and serratus blocks into a single thoracic fascial plane block, the SAP block

2019 ◽  
pp. rapm-2019-100745 ◽  
Author(s):  
Carlo D Franco ◽  
Konstantin Inozemtsev
Keyword(s):  
Brachial Plexus ◽  
Chest Wall ◽  
Mechanism Of Action ◽  
Sensory Innervation ◽  
Common Mechanism ◽  
Nerve Blocks ◽  
Intercostal Nerves ◽  
Lateral Branches ◽  
Fascial Plane Block ◽  
Fascial Plane

The popularity of ultrasound-guided nerve blocks has impacted the practice of regional anesthesia in profound ways, improving some techniques and introducing new ones. Some of these new nerve blocks are based on the concept of fascial plane blocks, in which the local anesthetic is injected into a plane instead of around a specific nerve. Pectoralis muscles (PECS) and serratus blocks, most commonly used for post op analgesia after breast surgery, are good examples. Among the nerves targeted by PECS/serratus blocks are different branches of the brachial plexus that traditionally have been considered purely motor nerves. This unsubstantiated claim is a departure from accepted anatomical knowledge and challenges our understanding of the sensory innervation of the chest wall. The objective of this Daring Discourse is to look beyond the ability of PECS/serratus blocks to provide analgesia/anesthesia of the chest wall, to concentrate instead on understanding the mechanism of action of these blocks and, in the process, test the veracity of the claim. After a comprehensive review of the evidence we have concluded that (1) the traditional model of sensory innervation of the chest wall, which derives from the lateral branches of the upper intercostal nerves and does not include branches of the brachial plexus, is correct. (2) PECS/serratus blocks share the same mechanism of action, blocking the lateral branches of the upper intercostal nerves, and so their varied success is tied to their ability to reach them. This common mechanism agrees with the traditional innervation model. (3) A common mechanism of action supports the consolidation of PECS/serratus blocks into a single thoracic fascial plane block with a point of injection closer to the effector site. In a nod to transversus abdominus plane block, the original inspiration for PECS blocks, we propose naming this modified block, the serratus anterior plane block.

scholarly journals A Robot Has a Mind of Its Own Because We Intuitively Share It

2020 ◽  
Vol 10 (18) ◽  
pp. 6531
Author(s):  
Mizuho Sumitani ◽  
Michihiro Osumi ◽  
Hiroaki Abe ◽  
Kenji Azuma ◽  
Rikuhei Tsuchida ◽  
...  
Keyword(s):  
Pain Intensity ◽  
Facial Expressions ◽  
Detection Threshold ◽  
Two Dimensions ◽  
Virtual Agent ◽  
Cold Pain ◽  
Detection Thresholds ◽  
Pain Detection ◽  
Pain Experiences ◽  
The Mind

People perceive the mind in two dimensions: intellectual and affective. Advances in artificial intelligence enable people to perceive the intellectual mind of a robot through their semantic interactions. Conversely, it has been still controversial whether a robot has an affective mind of its own without any intellectual actions or semantic interactions. We investigated pain experiences when observing three different facial expressions of a virtual agent modeling affective minds (i.e., painful, unhappy, and neutral). The cold pain detection threshold of 19 healthy subjects was measured as they watched a black screen, then changes in their cold pain detection thresholds were evaluated as they watched the facial expressions. Subjects were asked to rate the pain intensity from the respective facial expressions. Changes of cold pain detection thresholds were compared and adjusted by the respective pain intensities. Only when watching the painful expression of a virtual agent did, the cold pain detection threshold increase significantly. By directly evaluating intuitive pain responses when observing facial expressions of a virtual agent, we found that we ‘share’ empathic neural responses, which can be intuitively emerge, according to observed pain intensity with a robot (a virtual agent).

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