Palmar Nerve Research Articles

Anatomical and ultrasonographic landmarks of the manus nerves in camel (Camelus dromedarius)

This study aims to describe the anatomical and ultrasonographic features of manus nerves to establish a guideline approach for manus nerve block in camel practice. Twelve distal parts of the forelimbs cadavers of freshly slaughtered adult dromedary camels were used in this study. Six manus cadavers were used for anatomical morphology and the other six were used for ultrasonographic examination of the manus nerves. The gross anatomical study revealed the manus of the camel including, the third and fourth metacarpus and digits receives nerve supply from the ulnar, radial, and median nerves. These nerves continued along the camel manus as lateral and medial palmar metacarpal nerves and the axial and abaxial palmar proper digital nerves of the digits III and IV. Ultrasonographic evaluation of each nerve in the manus of the dromedary camel revealed proper localization and tracking of these nerves from the surrounding structures. In conclusion, the present study provides anatomical and ultrasonographic imaging knowledge tracking of the manus nerves in camels. This is important for determining the areas of the nerve block to attain successful regional anesthesia of this region in case of manus injuries in camel.

Dorsal-to-palmar branch neuroanastomosis in horses undergoing palmar digital neurectomy does not reduce neuroma formation or improve outcome.

Chronic foot pain, a common cause of forelimb lameness, can be treated by palmar digital neurectomy (PDN). Complications include neuroma formation and lameness recurrence. In humans, neuroanastomoses are performed to prevent neuroma formation. The aim of the study was to evaluate the outcome of horses undergoing dorsal-to-palmar branch neuroanastomosis following PDN. Retrospective case series. Eighty-five horses with PDN and dorsal-to-palmar branch neuroanastomosis. Medical records for horses undergoing this procedure at two hospitals between 2015 and 2020 were reviewed. Palmar and dorsal nerve branches of the PDN were transected and end-to-end neuroanastomosis was performed by apposition of the perineurium. Follow-up was obtained from medical records and telephone interviews. Success was defined as resolution of lameness for at least one year. Lameness resolved following surgery in 81/85 (95%) horses with 57/84 (68%) sound at one year. Postoperative complications occurred in 19/85 (22%) cases. The main limitations of the study were an incomplete data set, inaccurate owner recall, and variations in procedure. Compared to previous studies, this technique resulted in similar numbers of horses sound immediately after surgery, a comparable rate of postoperative neuroma formation but a higher recurrence of lameness rate at 1 year postoperatively. End-to-end neuroanastomosis of the dorsal and palmar branches of the PDN does not reduce the rate of neuroma formation in horses. Long-term outcome was less favorable compared to previously reported PDN techniques.

Radiofrequency Ablation of Palmar Digital Branches of Ulnar Nerve in a Patient with Ulnar Neuropathy

Ulnar Tunnel Syndrome (UTS) is ulnar neuropathy at the wrist or hand typically caused by ganglion cysts, lipomas, wrist or hand compression, carpal bone fractures, carpal tunnel syndrome, or anything else that can impinge on the nerve. The symptoms of UTS can be uncomfortable and debilitating, with numbness and tingling of the 4th and 5th digits being the most common. Weakness of the ulnar portion of the hand can lead to decreased grip strength. UTS is typically managed with conservative treatment including anti-inflammatory oral medications, splinting, physical therapy, activity modification, acupuncture, and stretching. Second line treatment includes corticosteroid injections, although these have shown to have little efficacy. Surgery is also an option but may lead to iatrogenic ramifications. Radiofrequency ablation (RFA) is a treatment modality used for chronic pain, which utilizes heat to target nociceptive fibers. Traditionally, RFA is used in treating cervical and lumbar radiculopathy, but it is less studied in peripheral nerve areas. This case report examines a patient who had clinically significant pain relief after RFA to the palmar digital branches of the ulnar nerve. The patient was 63-year-old male who presented with left ulnar neuropathy that had been ongoing for 3 years. Despite conservative management, his symptoms of pain, paresthesia, and weakness persisted. The patient then elected to have a left cubital tunnel release at the elbow with anterior subcutaneous transposition. The surgery provided relief for three months but then led to worsening contractures and pain in the 4th and 5th digits of the left hand. Due to persistent symptoms after conservative management and surgical intervention, he was referred to interventional pain clinic. A decision was made to trial a digital nerve block of the left medial and lateral digital palmar nerves. Following the nerve block, the patient reported 100% improvement in pain and increased range of motion and function. Four weeks later, the patient returned for a radiofrequency ablation of the same nerves. In the week following the procedure, the patient reported that the pain in the little finger was entirely resolved. While radiofrequency ablation has become increasingly popular for the treatment of chronic back pain, its use in peripheral nerve pain has been limited to case reports and few randomized control trials. This case report highlights the successful use of radiofrequency ablation in the treatment of little finger pain and ulnar neuropathy by targeting the median and lateral branches of the palmar digital nerve.

Ex vivo study shows novel, rapid, suture-free tenotomy technique for the equine deep digital flexor tendon.

To describe the feasibility of a novel thread-transecting technique for the tenotomy of the equine deep digital flexor tendon (DDFT). 39 equine distal limb specimens. Under ultrasonographic guidance, a surgical thread was percutaneously placed around the DDFT through 2 needle punctures (lateral and medial) using a Tuohy needle in equine limbs (22 forelimbs, 17 hindlimbs). The DDFT was transected by a back-and-forth motion of the thread until the loop emerged from the entry puncture site. Each specimen was dissected and assessed for completeness of transection and iatrogenic damage under direct visualization. Descriptive statistics were reported. Complete DDFT transection was achieved in all 39 limbs, taking an average of 8.6 minutes per procedure. Iatrogenic damage to surrounding structures occurred in 17 (44%) limbs, with 6 (15%) limbs having more than 1 structure damaged. Damage to the communicating branch of the palmar or plantar nerves was the most commonly seen. DDFT tenotomy in equine limb specimens was effectively performed using a novel thread-transecting technique. The procedure is quick, and no suturing is needed, but damage to surrounding structures is possible. Further assessment of the procedure and clinical significance of its potential iatrogenic damage in clinical cases is needed.

Clinical study of palmar foot pain in 30 polo ponies with forelimb lameness in Thailand

Palmar foot pain is an important chronic problem that impairs the abilities of sport horses. Though there are several research on different types of horses, there is a lack of information regarding polo horses, which are known for using in unique sport. Therefore, this research aimed to find the prevalence of palmar foot pain in polo ponies with forelimb lameness in Thailand. The horses included in this study were 30 Argentine polo ponies: 10 geldings and 20 mares, aged from 7 to 20 years old. All were barefoot and had not exercised for at least 2 months. The ponies underwent lameness examination procedures with subjective and objective evaluation, including a trot on a straight line, left and right lunging, a full forelimb flexion test and a toe wedge test. Close inspections of hoof conformation, hoof percussion and hoof testing were done before performing a palmar digital nerve block. The result showed that 25 (83.33%) of 30 polo ponies had forelimb lameness, which can be divided into 56.7% with unilateral forelimb lameness, and 26.7% with bilateral forelimb lameness. There were 17 (56.7%) polo ponies that responded positively to the full flexion test and 25 (83.33%) that responded positively to the hoof tester and percussion at the frog area. However, only 9 ponies (30%) were positive to palmar nerve block. In conclusion, this study reveals a notable incidence of forelimb lameness and palmar foot pain. Understanding palmar foot pain prevalence is vital for further equine health management.

Dose effect and duration of action of liposomal bupivacaine administered as a perineural analgesic in a reversible and adjustable frog-pressure model of equine lameness.

To determine the dose effect of peri-neural liposomal bupivacaine (LB) in an induced forelimb lameness model. 12 clinically normal adult horses. A randomized cross-over design was performed with 1 limb receiving saline and the other LB: low dose (6), high dose (6). Lameness was induced in 1 forelimb using a frog-pressure model. In the lame limb, peri-neural injection of the palmar nerves at the proximal sesamoid bones was performed using saline, low dose LB (0.25 mg/kg) (LDLB), or high dose LB (0.5mg/kg) (HDLB) in random order with a 1-week washout period between treatments. Distal limb swelling, mechanical nociceptive thresholds (MNT), and objective lameness data were collected before and up to 72 hours after peri-neural anesthesia. Data analysis was performed with mixed model ANOVA, equality of medians test, and Kaplan Meier survival analysis. Compared with baseline, horses treated with LDLB and HDLB had improvements in MNT and lameness (P < .001). In the LDLB group, the median duration of analgesia was 4.5 hours (range = 3-6 hours) and the median return to lameness was 7 hours (range = 4-24 hours). In the HDLB group, the median duration of analgesia was 12 hours (range = 4-48 hours) and the median return to lameness was 9 hours (range = 3-48 hours). Mild to moderate swelling was identified in 11/12 (92%) LB limbs. Both LDLB and HDLB resulted in loss of skin sensation and improvement of lameness. There was high variability among horses in duration of action for both doses.

Effect of 2% Topical Lidocaine Gel on Discomfort from Electrical Stimulation During Nerve Conduction Studies- A Prospective Double-Blind Placebo-Controlled Study.

Procedure discomfort can limit electrodiagnostic studies. Reducing discomfort can maximize the benefits of these diagnostic tools. This study targeted the discomfort associated with nerve conduction studies (NCS). This was a prospective randomized double-blind placebo-controlled study comparing the effect of topical lidocaine gel (2%) versus analgesic-free lubricant gel (K-Y gel) on pain perception during NCS. Sequential patients (n=130) referred for routine NCS participated in the study. We applied 1 mL of lidocaine gel to one palm, and 1 mL of K-Y gel to the other as a control. After 20-45 min of application, graded increments of electrical stimulation intensity were delivered to record the median and ulnar mixed palmar nerve responses. Patients were then asked to score the degree of pain felt from electrical stimulation over each palm using the Wong-Baker Faces Pain Scale (WBFPS) and the Numeric Rating Scale (NRS), independent of baseline pain. Mean WBFPS and NRS scores for lidocaine-treated palms were significantly lower than those for controls using parametric paired t-test (3.79 vs 4.37 and 3.35 vs 3.78 respectively, all p-values<0.05). Subgroup analysis showed a significant decrease in mean scores in females, patients aged ≤50 years, patients without a history of previous NCS, and patients without comorbidities (all p-values<0.05). Median scores using nonparametric Wilcoxon ranked test also showed statistically significant differences (all p-values<0.05). The results indicate that topical lidocaine 2% gel reduces discomfort associated with NCS. However, despite the statistical significance, clear clinical significance may be lacking. Clinical implementation may be considered for the subgroups that showed the greatest benefit. Further studies that incorporate more efficient drug delivery methods may yield better results.

The sensitivity of median versus ulnar palmar mixed nerve study in the early diagnosis of carpal tunnel syndrome

BackgroundElectrodiagnostic tests (EDX) are the most frequent and applicable studies in early diagnosis of carpal tunnel syndrome (CTS), but the definitive sensitive and specific tests are still under study. We aimed to evaluate the role of the median versus ulnar palmar mixed nerve study (Mix M-U), and its sensitivity in comparison to other provocative comparison studies, in supporting the early diagnosis of CTS. This cross-sectional study included 142 idiopathic early CTS hands from 100 patients and 71 hands from 50 healthy subjects as a control group. We did routine median motor and sensory studies and 4 comparative tests namely median versus radial sensory study (MVR), Mix M-U, median versus ulnar sensory study (MVU), and median versus ulnar lumbrical-interossei motor study (LU-IN).ResultsThe routine median motor and sensory latency and amplitude showed a statistically significant difference between CTS and control groups as (p< 0.05) and a highly statistically significant difference between the 2 groups as regards the 4 comparative tests as (p< 0.0001). The specificities of all the 4 comparative tests were higher than 90%. MVR test had the highest sensitivity (92.2%) and followed by Mix M-U study (82.2%) and MVU (78.7%), and the least sensitive test was the LM-IN (66.9%).ConclusionsAlthough the patients’ results fall within the normal range according to the reference range in the literature, it showed a statistically significant difference when compared to controls. A high percentage of those symptomatic patients showed results of typical CTS when tested with the comparative studies so there is a need to use these sensitive tests to diagnose cases with early CTS. According to sensitivity studies, the selection of which tests to do in order is a challenging choice. For the diagnosis of cases with early CTS with a normal ordinary motor and sensory studies, MVR comparative technique appeared as the best sensitive and specific provocative electrophysiological test followed by the Mix M-U test. We recommend the use of a combination of both tests first in the diagnosis of early CTS and if one of them was negative we can use the other comparative studies MVU and then LM-IN studies.

Transcarpal Motor Conduction Velocity: Repeatability and Application in Carpal Tunnel Syndrome.

Conduction velocity of the short segment of the median motor nerve, across wrist (transcarpal motor conduction velocity (TCMCV)), has been used to increase diagnostic yield in carpal tunnel syndrome (CTS). However, repeatability of this parameter has not been studied till date. It has not been used as an indicator of response to treatment. Using surface stimulation techniques, it is difficult to localize the sites of stimulation of transcarpal segment of median nerve in palm. As a result, small errors in measurements of TCMCV can be magnified and variability of TCMCV may occur on successive measurements. Despite this possible variation, TCMCV can be a useful tool for assessing response to therapy, if its repeatability is assessed and a cut-off value determined for a significant change in nerve conduction velocity. In this study, it was determined whether TCMCV is repeatable. If found to be repeatable, we show a method to determine the cut-off value of the change in this parameter for it to be considered significant. Difference between values of TCMCV on successive measurements was obtained in hands of 26 controls. Repeatability of this parameter was determined in this control population following criteria of British Standards Institution. In 19 patients of CTS, treated with intracarpal steroid injection, pre-treatment and post-treatment values of TCMCV, and of symptom severity scale (SSS) and functional status scale (FSS), were obtained at 1, 2, and 3 months after treatment. Repeat measurements of TCMCV were made in each hand of all controls. After applying criteria of British Standards Institution, to such recordings, TCMCV was found to be repeatable and the cut-off value for significant change determined. According to this cut-off value, 4 patients of CTS showed improvement in TCMCV, with consistent improvement in SSS and FSS. Change in TCMCV corroborated qualitatively with changes in SSS and FSS. Repeatability of TCMCV can be assessed by criteria of British Standards Institution and a cut-off value determined to use it as an indicator of response to treatment in CTS.

Entrapment of the palmar cutaneous branch of the median nerve: A neuropathy difficult to notice

Palmar cutaneous branch of the median nerve (PCBMN) arises at average 7 cm proximal to and at the radial side of the distal wrist crease. Isolated entrapment of PCBMN is rare and difficult to detect. The literature review only yielded case reports. In this study, we wanted to present two cases of rare palmar cutaneous nerve entrapment, wherein one patient was treated conservatively and the other one with surgery. In conclusion, pain and discomfort in the thenar region may be a manifestation of palmar cutaneous nerve entrapment. Careful evaluation and treatment planning are essential in these patients.

Minimally Invasive Carpal Tunnel Release Using a Hook Knife through a Small Transverse Carpal Incision: Technique and Outcome.

Compared to the classic open technique, limited exposure techniques have the advantages of less scar pain, more grip and pinch strength, and earlier return to daily life. We evaluated the effectiveness and safety of our novel method of minimally invasive carpal tunnel release using a hook knife through a small transverse carpal incision. This study included 111 carpal tunnel decompressions in 78 patients who underwent carpal tunnel release from January 2017 to December 2018. We performed carpal tunnel release using a hook knife through a small transverse incision just proximal to the wrist crease under local infiltration of lidocaine with tourniquet inflation in the upper arm. All patients were tolerable during the procedure and discharged following the procedure on the same day. At an average of 29.4 months of follow-up (range, 12-51 months), all but one patient (99%) revealed complete or near complete symptomatic recovery. The average of the symptom severity score on the Boston questionnaire was 1.31 ± 0.30 and the average of the functional status score was 1.19 ± 0.26. The final mean Quick Disabilities of the Arm, Shoulder, and Hand questionnaire (QuickDASH) score was 8.66 (range, 2-39). There was no superficial palmar arch injury or nerve injury of the palmar cutaneous branch, recurrent motor branch, or median nerve itself as a complication of the procedure. No patient showed any wound infection or wound dehiscence. Our carpal tunnel release using a hook knife through a small transverse carpal incision performed by an experienced surgeon is a safe and reliable method that is expected to have the benefits of simplicity and minimal invasiveness.

Pronator Quadratus: A Preferable Recipient for Targeted Muscle Reinnervation of Neuromas in the Hand.

Targeted muscle reinnervation (TMR) has emerged as a useful solution to the problem of painful neuromas and is increasingly being applied in many clinical circumstances. Relatively little has been written about TMR for painful neuromas of the hand, and what has been written describes use of the intrinsic muscles as recipients for the nerve transfer. Except in cases of amputation, intrinsic muscle sacrifice carries morbidity. Furthermore, TMR to intrinsic muscles will place the nerve coaptation in areas subject to pressure with loading of the palm. For these reasons, the pronator quadratus may be a preferable target muscle when performing TMR for painful neuromas of the hand. In this report, we describe the rationale for its use and demonstrate the surgical technique and outcomes with case examples.

High-frequency Ultrasonography of the Digital and Palmar Nerve Branches of the Hand in Peripheral Nerve Diseases.

Peripheral nerve ultrasound is a well-established imaging technique to evaluate certain peripheral nerve pathologies. However, there is a poor correlation between ultrasound abnormalities of peripheral nerves and electrodiagnostic or clinical evidence of axonal loss. This is a significant limitation of peripheral nerve ultrasound, as many peripheral nerve diseases encountered in clinical settings are related to axonal loss. Furthermore, clinical and electrodiagnostic evidence of axonal loss directly correlates with disability in all peripheral nerve diseases. However, due to the floor effects often encountered in electrodiagnostic studies, these correlations, as well as definitive diagnoses, are often challenging. Thus, imaging techniques that correlate with axonal loss are essential for expanding the utility of peripheral nerve ultrasound as a potential biomarker for peripheral nerve diseases. With new technological advancements and the ever-increasing imaging capabilities of high-frequency ultrasound, the palmar and digital nerve branches of the hand can be imaged with exceptionally high resolution even using point-of-care ultrasound devices. Their superficial and distal-most anatomic locations are ideal for evaluating polyneuropathies, as these branches degenerate earliest during axonal loss. However, no studies have systematically evaluated these nerve branches to determine if they can be reproducibly measured with ultrasound. The current protocol was adapted for the systematic assessment of cross-sectional areas of the median and ulnar nerves in the palmar surface and digits of the hand. This protocol provides reference data for a subset of nerves that demonstrate high intraclass correlation coefficients between three separate ultrasonographers. Finally, as a proof of concept and to demonstrate the clinical applications of this protocol, representative data from individuals with genetically confirmed inherited polyneuropathies are compared with established normative data to examine cross-sectional area differences.

Preservation of terminal branches of the palmar cutaneous branch of the median nerve in open carpal tunnel release.

Post-operative pain in the palm and scar area is the most common complication after carpal tunnel release and injury to the terminal branches of the palmar cutaneous nerve is generally considered one of the causes for this complication. The Authors performed an intraoperative study preserving the terminal branches of the palmar cutaneous branch of the median nerve and verifying the frequency, location and direction of the branches that cross an interthenar incision. Eighty-five consecutive patients (57 F - 28 M, mean age 66 y) underwent carpal tunnel release between February and June 2021. The cutaneous branches crossing the incision were identified and preserved by careful dissection. Subsequently they were counted and classified by their direction and distance from the proximal border of the transverse carpal ligament. Sensory branches were found in 40 % of cases (34/85) and their origin was observed at an average of 1.05 cm (0-1.8 cm) distal from the proximal border of the carpal tunnel. A total of 44 branches were observed of which 23 branches crossed the incision with a transverse course and 21 with an oblique, generally proximal-distal radio-ulnar course. The subcutaneous layer overlying the distal third of the transverse carpal ligament was found to be devoid of sensory branches, therefore it can be considered a relatively safe area. Isolation and protection of palmar sensory branches is important for improving carpal tunnel release results. This goal can be more easily achieved by locating the skin incision on the distal third of the transverse carpal ligament, where the sensory branches have a lower frequency, possibly associated with a second proximal incision (biportal technique) to better visualize the proximal portion of the ligament and antebrachial fascia.

Bifid median nerve: a case report at the wrist

The median nerve is a terminal branch of the brachial plexus. It arises in the axilla and ends in the hand by dividing into three common palmar nerves after passing through the carpal tunnel deep to the flexor retinaculum at the wrist. The bifid median nerve corresponds to a bifurcation of the median nerve trunk inside the carpal tunnel. It is a rare variation that is often associated with the persistence of the wrist median artery. The authors report here a fortuitous discovery of a case of bifid median nerve during the wrist dissection of a cadaverous melanoderm belonging to the Wolof ethnic group in Senegal. The bifurcation started at about 14 cm distal and lateral to the medial bicipital groove with the medial trunk ending in the third interdigital space and the lateral trunk which gave four branches. There was neither the wrist median artery nor any other variations of the normal structures at the wrist. The bifid median nerve is rare but should be kept in mind. Being aware of this kind of variation is important to avoid nerve lesions during carpal tunnel surgery.

Construction Worker with Painful Swelling on the Hand

A 27-year-old right-handed construction worker presented to the emergency department with a 1-week history of an enlarging, rounded, and painful swelling at the base of the right thumb (Figure 1). A history of trauma was denied. On clinical examination, there was no numbness or paresthesia. However, the Tinel sign of the palmar thumb nerve was positive. Capillary refill was normal. Leucocyte count and C-reactive protein level were within the normal range. Point-of-care sonography showed a subcutaneous, hypoechogenic lesion of 3 × 2 × 1 cm over the thenar muscles with substantial vascularization (Figure 2).

Desensitisation of the distal forelimb following intrathecal anaesthesia of the carpal sheath in horses.

The effect of intrathecal anaesthesia of the carpal sheath on distal forelimb sensitivity in horses remains unknown. To assess the effect of carpal sheath anaesthesia on skin sensitivity of the distal forelimb and to determine potential locations for desensitisation of palmar nerves. In vivo experimental and descriptive anatomical studies. Mepivacaine hydrochloride 2% (0.6mg/kg) was injected unilaterally in the carpal sheath of 8 horses. Mechanical nociception of the distal forelimb was measured with a dynamometer and compared with the control limb at t0, t15, t30, t60, t90, t120 and t180minutes . Additionally, the carpal sheath of 10 pairs of cadaveric limbs was injected with latex and potential locations for anaesthetic diffusion to the neighbouring nerves were identified during longitudinal dissection (one limb) and in 3-cm-thick transverse cuts (opposite limb). Six of 8 horses (75%) were completely desensitised at the level of both heel bulbs. Anaesthetic injection was not smooth in the 2 horses without desensitisation. Desensitisation started between 30 and 60minutes in 67% of desensitised heel bulbs (8/12), and 50% (6/12) of them were still completely desensitised at 180minutes. Cadaveric specimens revealed close proximity between the sheath and the medial palmar nerve as it travels inside the mesotenon of the digital flexor tendons in the carpal region and with both palmar nerves at the proximal metacarpal region. Skin mechanical nociception does not necessarily correlate with deep pain but remains the main clinical tool used by practitioners to assess distal limb anaesthesia. Intrathecal anaesthesia of the carpal sheath led to distal limb skin desensitisation through diffusion to the palmar nerves at 2 possible locations. Carpal sheath anaesthesia should be interpreted within 15minutes following injection and anaesthetic blocks distal to the carpus should be delayed for more than 3hours following carpal sheath anaesthesia.

Digit innervation of the thoracic limb of Criollo horses: Anatomical description and consequences to perineural blocks.

Criollo horse breeding is an important economic activity in South America. Because of their athletic performance, these animals tend to show great incidence of musculoskeletal disorders, many of them diagnosed by means of perineural blocks. However, incorrect interpretation of these blocks may be due to anatomical differences in nerve distribution. The objective of this study was to describe the innervation of the digit region of thoracic limbs in Criollo horses, in order to improve the interpretation of tests for claudication diagnosis based on nerve block. Thirty thoracic limbs from Criollo horses were dissected. It could be observed that in 90% of the limbs, dorsal branches of the palmar nerve originated proximally to the proximal sesamoid bone. In 93% of the cases, the palmar digital nerve and the dorsal branches communicated; in 87% of the cases, communication between branches of the dorsal branch was observed; and in 27% (8/30) of the limbs, the palmar metacarpal nerve and the dorsal branch presented communications. None of the specimens showed complete symmetry in the distribution of nerves in contralateral limbs. The high frequency of communication between the nerves may be a particularity of the Criollo breed that may interfere with the interpretation of perineural blocks. Based on the anatomical position, it may be inferred that divergent results in Criollo horses may occur when abaxial sesamoid nerve block is used. Palmar digital nerve block may be less influenced by these variations, provided it is performed as distal as possible from the ungular cartilage.

Systemic and local effects of lidocaine or mepivacaine when used for intravenous regional anaesthesia of the distal limb in standing sedated horses.

Local anaesthetics are being combined clinically with amikacin in intravenous regional limb perfusion (IVRLP), with limited knowledge on the analgesia provided and its onset and duration of action after tourniquet application and release. To evaluate the systemic clinical effect, limb withdrawal to nociceptive stimulation, and plasma and synovial fluid concentrations after IVRLP with lidocaine or mepivacaine in standing sedated horses. Prospective, controlled, randomised, cross-over study. Six healthy adult horses were sedated and received IVRLP with lidocaine, mepivacaine or saline (negative control), or perineural anaesthesia of the medial and lateral palmar and palmar metacarpal nerves (positive control) in one forelimb with a 3-week washout period between trials. Electrical and mechanical stimuli were used to test nociceptive threshold of the limb before and after IVRLP/perineural anaesthesia. For lidocaine and mepivacaine trials, blood was collected from the jugular vein and synovial fluid from the radiocarpal joint before, during and out to 24hours after IVRLP. Drug concentrations were measured using high-performance liquid chromatography. Nociceptive thresholds for lidocaine, mepivacaine and perineural anaesthesia trials were significantly increased compared with saline and baseline values at 10, 20 and 30minutes, with no differences between anaesthetic trials. During this time, horses had lower heart rates than IVRLP with saline. After tourniquet release at 30minutes, nociceptive thresholds for lidocaine and mepivacaine trials gradually returned to baselines, whereas perineural anaesthesia trial remained unchanged out to an hour. Plasma lidocaine and mepivacaine concentrations were ≤50ng/mL while the tourniquet was in place, significantly increasing 10minutes after tourniquet release. Maximal lidocaine and mepivacaine concentrations in synovial fluid were reached 25minutes after IVRLP injection. Amikacin was not included in the perfusate. Similar to perineural anaesthesia, IVRLP with lidocaine or mepivacaine provides anti-nociception to the distal limb in standing sedated horses while a tourniquet is applied with concentrations remaining below toxic levels in plasma and synovial fluid.

Pacinian corpuscles in the human fetal foot: A study using 3D reconstruction and immunohistochemistry

PurposeOur group had recently described human hand Pacinian corpuscles (PCs): the hand PCs are not simply arranged along the digital palmar nerves but often exhibited specific morphologies known uncommonly. However, there is still no or few information about human foot PCs. Materials and methodsWe observed transverse sections of all five toes including the interdigital area obtained from 12 feet of eight fetuses at 28–33 weeks (crown-rump length 230–290mm). Serial sections were prepared for 3D reconstructions and measurement. ResultsFoot PCs were characterized by (1) a dense distribution in the interdigital area in contrast to a few PCs in the distal tip of the all five toes; (2) abundant dorsal PCs including those in the nail bed and: (3) a long chain of PCs in the flexor tendon sheath of all five toes. Therefore, a distal dominance was not evident in the foot in contrast to the hand and, a tendon sheath contained much greater numbers of PCs than the hand. A tree-like or bouquet-like arrangement of PCs along a short perforating artery to the palmar digital skin was seen in the foot as we had described in the hand. The tree of foot PCs was sometimes seen laying transversely along the digital skin surface, not toward the skin. ConclusionIt is still unknown that, in utero, how the PCs distribution became different between the hand and foot: it might be determined genetically in a region-specific manner.