Interosseous Nerve Research Articles

Use of Wrist Denervation in the Treatment of SLAC and SNAC Wrist by ASSH Members.

Background Scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) are common patterns of wrist arthritis, and surgical treatment options include partial and total wrist arthrodesis and wrist denervation, which maintains the current anatomy while relieving pain. Introduction The purpose of this study is to elucidate current practices within the hand surgery community with respect to the use of anterior interosseous nerve/posterior interosseous nerve (AIN/PIN) denervation in the treatment of SLAC and SNAC wrists. Methods An anonymous survey was distributed to 3,915 orthopaedic surgeons via the American Society for Surgery of the Hand (ASSH) listserv. The survey collected information on conservative and operative management, indications, complications, diagnostic block, and coding of wrist denervation. Results In total, 298 answered the survey. 46.3% ( N = 138) of the respondents used denervation of AIN/PIN for every SNAC stage, and 47.7% ( N = 142) of the respondents used denervation of AIN/PIN for every SLAC wrist stage. AIN and PIN combined denervation was the most common standalone procedure ( N = 185, 62.1%). Surgeons were more likely to offer the procedure ( N = 133, 55.4%) if motion preservation had to be maximized ( N = 154, 64.4%). The majority of surgeons did not consider loss of proprioception ( N = 224, 84.2%) or diminished protective reflex ( N = 246, 92.1%) to be significant complications. 33.5%, 90 respondents reported never performing a diagnostic block prior to denervation. Conclusion Both SLAC and SNAC patterns of wrist arthritis can result in debilitating wrist pain. There is a wide range of treatment for different stages of disease. Further investigation is required to identify ideal candidates and evaluate long-term outcomes.

Median ulnar nerves communication in the forearm: a study with autopsy material.

The incidence of median-ulnar communication in the forearm presents variability in different population groups. The aim of this study was to determine the incidence and morphologic expression of the median-ulnar communication in a sample of the Colombian population. One hundred and eight forearms of autopsy material at the National Institute of Forensic Medicine of Bucaramanga, Colombia were studied. Using an approach of the flexor compartment of forearm the median and ulnar nerves were dissected and the communications between these two structures were characterized. The communicating branch occurred in 28 (25.9%) forearms. It occurred unilaterally in 12 specimens and bilaterally in 8, with statistically significant difference (P=0.01). The communication between the anterior interosseous and ulnar nerves was most frequent, observed in 13 (46.4%) forearms. The length of the communicating branch was 56.9 +/- 8.3 mm. The distance of the proximal and distal points of the communicating branch to the bi- epicondylar line was 59.6 +/- 15.4 mm and 102.7 +/- 23.5 mm respectively. The length of the forearm was 269.8 +/- 15.9 mm. A projection of the communicating branch from the upper third to the midthird of the forearm was observed. The incidence of the median-ulnar communication in the present study is in the high rank reported in the literature; there is an agreement with prior studies in finding more numerous communicating branches in the right forearm. The median-ulnar communication should be taken into account for surgical approach of the forearm.

Evaluation of Early Postoperative Pain and the Effectiveness of Perifracture Site Injections Following Volar Plating for Distal Radius Fractures

Few studies have investigated the effectiveness of early postoperative pain control regimens after volar plating for distal radius fractures. This study evaluated postoperative levels of pain after volar plating of distal radius fractures under axillary nerve block in patients with and without injections of local anesthetics, narcotics, and epinephrine around the fracture site. Perioperative pain levels were prospectively assessed in 44 consecutive patients who had had volar plating for a distal radius fracture under axillary nerve block at a mean time of 2.8 days after trauma. Intravenous, patient-controlled analgesia and prescheduled analgesic medications were administered to all patients. In addition, patients were randomly allocated to 2 groups: perifracture site injection (PI; n = 22) and no perifracture site injection (no-PI; n = 22). At the end of surgery, PI group patients were administered perifracture site injections and blocks of the superficial radial and interosseous nerves with a local anesthetic mixture consisting of ropivacaine, morphine, and epinephrine. During the first 48 hours after surgery, pain visual analog scale (VAS) scores (0 to 100), total amount of narcotic consumption, incidences of additional narcotic requirement, and opioid-related side effects were assessed. The overall mean pain VAS scores among all 44 study subjects were 29 before surgery, and 58, 47, 40, and 27 at 4, 8, 24, and 48 hours after surgery, respectively. Thirteen patients needed additional pain rescue despite the multimodal analgesic approach used. No intergroup differences were observed between the PI and no-PI groups in terms of VAS pain scores, total narcotic consumption, adjuvant pain rescue incidence, and opioid-related side effects. Postoperative mean pain VAS scores after volar plating of distal radius fractures were found to be 58 at 4 hours and 47 at 8 hours. Perifracture site injections were not found to provide any additional pain control benefit. Therapeutic II.

Primary afferent depolarization of myelinated fibres in the joint and interosseous nerves of the cat.

1. Changes in the excitability of the intraspinal terminals of fibres in the posterior knee joint and interosseous nerves were used as a measure of primary afferent depolarization (PAD) which is associated with presynaptic inhibition of transmission from afferent fibres. These were estimated from changes in the intensity of electrical stimuli required to activate the fibres in 50% of trials. In order to avoid the inclusion of group I muscle afferents which contaminate the joint and interosseal nerves, the analysis was restricted to fibres conducting at less than 75 m s-1 and/or displaying patterns of PAD which differed from those of group Ia and Ib muscle afferents in lower lumbar segments of anaesthetized cats. PAD was evoked by electrical stimulation of ipsilateral hindlimb nerves. 2. PAD of fibres in the posterior knee joint nerve was induced from group I (Ia and Ib) and group II muscle afferents and cutaneous afferents but not by stimulation of the joint or the interosseous nerves. The most effective stimuli were those applied to the superficial peroneal, sural, quadriceps and posterior biceps and semitendinosus nerves. 3. PAD of fibres in the interosseous nerve was also induced by stimulation of group I (Ia and Ib) and group II muscle afferents and cutaneous afferents and, in addition, by stimulation of joint and interosseous nerves. The most effective stimuli were those applied to the superficial peroneal, quadriceps, flexor digitorum longus and posterior biceps and semitendinosus nerves. 4. Individual fibres of the joint and the interosseous nerves were depolarized by only some of the conditioning stimuli. Even the most effective stimuli did not produce PAD in all of the fibres tested. Individual fibres of the joint and the interosseous nerves were depolarized by diverse combinations of afferents of different functional types and of different peripheral nerves. The differences in the sources of PAD were not associated with the conduction velocities and hence are unlikely to be related to differences in the receptor origin of the tested fibres. The diversity in the sources of PAD of individual fibres is interpreted as providing a high degree of differentiation in the control of transmission from receptors in joints and interosseal membranes.

Information processed by dorsal horn spinocerebellar tract neurones in the cat.

1. A group of spinocerebellar tract neurones located in the dorsal horn of the mid-lumbar segments of the spinal cord but outside of Clarke's column have been investigated by intracellular and extracellular recording from their somata. The existence of these neurones has been demonstrated previously using anatomical methods, but their properties have not been investigated in detail. In contrast to the cells of Clarke's column, these neurones were found to process information from both exteroceptors and proprioceptors. 2. All of the investigated neurones were powerfully excited following stimulation of muscle nerves at strengths sufficient to activate group II afferents while there was no evidence for actions from group I afferents onto any of them. Most were excited by group II afferents from many different nerves, including those from muscles acting on different joints. The latencies and properties of the excitatory postsynaptic potentials (EPSPs) suggest that at least a large proportion of them were monosynaptically evoked. 3. All of the neurones were powerfully excited following electrical stimulation of cutaneous afferents. The most potent effects were evoked from the saphenous and sural nerves which innervate the skin of the leg and thigh. In many cases these EPSPs had latencies indicative of a monosynaptic connection. The superficial peroneal and tibial nerves which innervate the skin of the foot evoked EPSPs which were usually smaller and of longer latency. 4. Responses to adequate stimulation of cutaneous afferents were examined in twenty extracellularly recorded neurones. All but one of them could be discharged by weak mechanical stimulation of the skin over the proximal part of the leg and thigh. None were activated from the skin of the foot. 5. Some of the neurones were influenced by stimulation of the posterior knee joint or interosseous nerves. These actions were relatively weak, however, suggesting that the powerful effects seen on stimulation of muscle nerves were unlikely to have been mediated by articular or Pacinian afferents which contaminate them. 6. Excitation from group II afferents was sometimes followed by inhibition (in 27% of the neurones). In almost all cases the inhibitory postsynaptic potentials (IPSPs) were evoked from the same nerves which evoked EPSPs. The minimal latencies of the IPSPs were approximately 1.0 ms longer than those of the EPSPs, suggesting that they were evoked disynaptically. 7. The possibility that these neurones provide information regarding limb position is discussed.

An interneuronal relay for group I and II muscle afferents in the midlumbar segments of the cat spinal cord.

1. The properties of interneurones located in the 4th lumbar segment of the cat spinal cord (L4 interneurones) have been investigated by intracellular and extracellular recording from individual neurones. The study focused on interneurones projecting to hind-limb motor nuclei and/or interposed in pathways from group II muscle afferents. The projection to motor nuclei was assessed from antidromic activation of the neurones by stimuli applied in the motor nuclei of the 7th lumbar (L7) segment. 2. Interneurones which projected to gastrocnemius-soleus or hamstring motor nuclei were found in laminae VI and VII and at the border between laminae VII and VIII. The dominant peripheral input to most of them was from group II muscle afferents, but they were also influenced by group I muscle afferents and by afferents in cutaneous, joint and interosseous nerves. Both excitatory post-synaptic potentials (e.p.s.p.s) and inhibitory post-synaptic potentials (i.p.s.p.s) were evoked from all of these fibre systems. 3. The same kind of multimodal input was also found in other interneurones in laminae VI and VII. However, their axonal projections were not identified and they might have included neurones projecting to motor nuclei (though outside the areas which were stimulated) as well as neurones with more local actions. 4. Interneurones located in laminae IV and V of the dorsal horn appeared to constitute a separate functional population since both their projections and their input differed from those of the more ventrally located interneurones; none of the dorsal horn interneurones were found to project to motor nuclei and none had input from group I afferents, although they were influenced by group II muscle afferents and by afferents in cutaneous, joint and interosseous nerves. 5. Many of the excitatory actions from group I and II afferents upon L4 interneurones were found to be evoked monosynaptically. A high proportion of L4 neurones synapsing upon motoneurones would thus be interposed in disynaptic reflex pathways from these afferents. In comparison to actions evoked via interneurones of the caudal lumbar segments, any post-synaptic potentials (p.s.p.s) evoked via L4 interneurones would be delayed. These delays would amount to 0.4-0.9 ms for p.s.p.s. from group I afferents and by 0.5-2.5 ms for group II p.s.p.s. 6. In many interneurones, particularly those located ventrally, i.p.s.p.s. were evoked by group I and II muscle afferents at latencies which indicated that they were evoked disynaptically. They may therefore reflect inhibitory interactions between subpopulations of L4 interneurones.(ABSTRACT TRUNCATED AT 400 WORDS)

Field potentials generated by group II muscle afferents in the middle lumbar segments of the cat spinal cord.

1. A powerful projection from group II muscle afferents of hind-limb muscles to the 3rd, 4th and 5th segments of the lumbar spinal cord has been demonstrated by focal synaptic field potential recording. 2. Field potentials were found at two locations: one in the dorsal horn (Rexed's laminae IV and V) and the other in the intermediate zone and ventral horn (Rexed's laminae VII and VIII). In the dorsal horn the field potentials were exceptionally large and were evoked only by group II afferents. At more ventral locations, they were smaller and were sometimes preceded by small field potentials evoked by group I afferents. 3. At both locations field potentials could be evoked by stimulation of a number of hind-limb muscle nerves at strengths sufficient to activate group II afferents. However, some nerves consistently evoked more powerful effects than others and the largest potentials were from the nerves to quadriceps, sartorius and to the pretibial flexor muscles (tibialis anterior and extensor digitorum longus). Activation of articular afferents (from the knee joint nerve) or Pacinian corpuscle afferents (from the interosseous nerve) evoked small field potentials at some locations. 4. In the dorsal horn the latency of the field potentials was so short that they must have been generated monosynaptically. Field potentials in the ventral horn had longer latencies, by 0.5-1.0 ms, but they also appear to have been monosynaptically evoked by slowly conducting intraspinal collaterals. This conclusion is based primarily on the effects of intraspinal stimulation which was found to antidromically activate afferents with the appropriate latencies and thresholds. 5. Evidence is presented that the dorsal and ventral field potentials are generated by afferents whose receptors can be activated by small (less than 100 micron) muscle stretches.

Sources of input to interneurones mediating group I non‐reciprocal inhibition of motoneurones in the cat.

Intracellular recordings have been made from laminae V-VI interneurones interposed in pathways of non-reciprocal inhibition of motoneurones from group I afferents of triceps surae and/or plantaris. A comparison of actions of brief stretches of triceps surae and plantaris with actions of electrical stimulation of nerves of these muscles revealed that I a afferents influenced about a half of the interneurones excited by I b afferents. Electrical stimulation of seven muscles nerves, three cutaneous nerves, posterior knee joint and interosseous nerves, the red nucleus and the pyramidal tract, evoked excitatory post-synaptic potentials (e.p.s.p.s) in various proportions of interneurones. Most of the interneurones were excited monosynaptically, or both monosynaptically and disynaptically by group I afferents. This, together with a very small proportion of interneurones in which e.p.s.p.s were evoked only disynaptically, indicates that the same last-order interneurones may subserve di- and trisynaptically evoked inhibition of motoneurones. Other fibre systems excited these interneurones monosynaptically (interosseal, rubro- and corticospinal), disynaptically (cutaneous, rubro- and corticospinal) and polysynaptically. The coupling of the earliest e.p.s.p.s from group II and joint afferents could not be established, but was consistent with their mediation by only one or two interposed interneurones. Inhibition was evoked from all fibre systems with excitatory input to the same or to other interneurones of the sample, except from group II afferents, the effects of which were found in a much smaller number of cells and may not be fully representative.

Distribution of oligosynaptic group I input to the cat medial gastrocnemius motoneuron pool.

To characterize the oligosynaptic group I afferent input to the cat medial gastrocneumius (MG) motoneuron pool, the medial branch of the tibial nerve (MTIB: flexor digitorum and hallucis longus, popliteus, tibialis posterior and interosseous nerves), the nerves to flexor digitorum and hallucis longus (FDHL), or the nerves to the quadriceps muscles (QUAD) were stimulated at submaximal group I strength while recording intracellularly from MG motoneurons. Since previous work indicates that stimulation of these nerves at group I strength produces no significant monosynaptic Ia excitation or Renshaw inhibition of MG motoneurons, group I effects were assumed to be predominantly, though not exclusively, due to the action of Ib-fibers. Evidence supporting this assumption is presented in the following paper. MTIB, FDHL, and QUAD postsynaptic potentials (PSPs) were most commonly inhibitory. Since the MTIB, FDHL, and QUAD nerves are composed predominantly of fibers innervating muscles with extensor action, their inhibitory effect on MG motoneurons is consistent with previous findings that stimulation of Ib-afferents in nerves to extensor muscles produces di- and trisynaptic inhibition of extensor motoneurons. However, excitatory effects were observed in about one third of the motoneurons, indicating that oligosynaptic group I input is not homogeneously distributed within the MG motoneuron pool. Variations in QUAD, FDHL, and MTIB PSP pattern and amplitude were correlated with variations in the PSP pattern evoked by stimulation of the sural nerve: excitatory oligosynaptic group I PSPs generally appeared in motoneurons receiving excitatory cutaneous (sural nerve) input, whereas inhibitory PSPs generally appeared in motoneurons receiving some inhibitory cutaneous input and were largest in motoneurons receiving predominantly inhibition from the sural nerve. These variations in QUAD, FDHL, and MTIB PSP pattern and amplitude were not due to variations in resting potential and were only partly due to variations in intrinsic motoneuron properties or motoneuron "type." Our results indicate that activation of these cutaneous and group I muscle afferents can exert similar effects on the MG motoneuron pool. Moreover, the presence of a strong correlation between the distributions of cutaneous and oligosynaptic group I PSPs within a single motoneuron pool is consistent with the results of previous studies that have shown that some of the input to motoneurons from these peripheral afferents is mediated through common interneurons.

The effect of long-term denervation on the ultrastructure of Pacinian corpuscles in the cat.

The ultrastructure of Pacinian corpuscles of the cat located in the crural region and innervated by the interosseous nerve was studied 1 to 14 months after denervation. Both the Pacinian inner core and capsule remained well preserved one month after denervation. However, the denervated inner cores underwent progressive atrophy and wasting, which resulted in a gradual reduction of the amount of inner-core cells and lamellae, widening of interlamellar clefts, formation of empty spaces in the axial region and a considerable increase in the number of collagen fibrils. In spite of the wasting, the inner core still survived 14 months after denervation, but at least half of its volume became occupied by collagen fibrils which surrounded the remaining inner-core cells and lamellae. Collagen fibrils assembled in the denervated core were markedly thinner than those found in the capsule, as is also the case in normal Pacinian corpuscles. In the capsule, discrete focal degeneration, occasional pyknosis of the innermost capsular cells and macrophage infiltration were observed from the first month after nerve section onward, but the number of capsular layers remained within the normal range (30-40) up to 14 months after denervation.

Pioneer growth cones in virgin mesenchyme: an electron-microscope study in the developing chick wing

Axons grow out along predictable routes of specific destinations. An EM study of the early development of one of the main chick wing nerves - the interosseous nerve - helps to show how they do it. The growing tip of the nerve appears frayed, consisting of nerve fibres occurring singly or in small bundles, taking slightly divergent paths. Most of these pioneer nerve fibres have the characteristic appearance of growth cones. They are not seen to advance along fibrils of the intercellular matrix (as one might expect from some tissue culture experiments), but instead are generally in close contact over their whole surface either with mesenchyme cells or with other nerve fibres. The same is true of the axons at more proximal levels of the developing nerve: they too are never naked, but always in contact either with other axons or with mesenchyme cells. Later nerve fibres follow the pioneers: their growth cones travel out in contact with the pre-existing axons, within the primitive perineurium formed by the enveloping mesenchyme cells, and most often close to the periphery of the fascicle.

Lipoma, a cause of paralysis of deep radial (posterior interosseous) nerve

Lipoma, a cause of paralysis of deep radial (posterior interosseous) nerve

Post-synaptic excitation and inhibition from primary afferents in neurones of the spinocervical tract.

1. Intra- and extracellular recordings were made from cells of the spinocervical tract in the lumbosacral spinal cord. A convergence of monosynaptic excitatory post-synaptic potentials (EPSPs) and disynaptic inhibitory post-synaptic potentials (IPSPs) was a general pattern of effects from the low threshold cutaneous fibres. Unitary IPSPs, probably mediated via the same disynaptic path, were evoked by light touch of hairs, which was also the adequate stimulus for exciting the cells. The receptive field for unitary IPSPs was closely related to the excitatory receptive field but was eccentric, not of a surround type.2. EPSPs, IPSPs, or both, were evoked from the flexor reflex afferents in the great majority of neurones. Disynaptic IPSPs may be evoked from the interosseous nerve. No effects were produced by volleys in group I muscle afferents.3. It is suggested, on the basis of the spatial organization of the excitatory and inhibitory receptive skin fields, that the spinocervical tract may give information regarding the direction of tactile stimuli.

Cortical responses to impulses from single Pacinian corpuscles in the cat's hind limb

Individual Pacinian corpuscles situated near the cat's crural interosseous membrane were exposed and stimulated with weak mechanical pulses delivered by a piezo-electric transducer element, impulses so initiated being monitored in the interosseous nerve. With the nerve intact, single impulses were found to be capable of evoking in contralateral area II small predominantly surface-positive cortical potentials, usually less than 40 μV in amplitude. In some instances, use of an averaging computer was necessary to reveal their presence. When two impulses from the same or from different corpuscles were set up at various time intervals, summation or occasionally facilitation of cortical response occurred at short intervals followed by depression persisting for several hundred msec: single impulses also depressed the response to subsequent electrical stimulation of the nerve. These observations confirm the great security of transmission at synapses interposed on pathways to cortex, and demonstrate the occurrence of considerable spatial and temporal spread of action from the single active input fibre.