Histological identification of Lugaro cells in the cat cerebellum

Segmental loss of a peripheral nerve has been a challenging reconstructive problem. Management of the nerve gap has been accomplished classically with nerve grafting. However, autogenous nerve grafts are not always available for bridging large nerve gaps, and clinical results of large nerve cable grafts have been disappointing. Newer techniques concentrate on nerve lengthening with different methods. Tissue expansion of peripheral nerves has been producing promising results. Since the introduction of the Ilizarov external fixator, much attention has turned to limb-lengthening techniques and studies investigating the results of nerve and soft tissues lengthened during the course of this procedure. Primary nerve distraction may be an alternative to nerve elongation, by expansion or nerve grafting to repair the peripheral nerve gap. This study describes a device and a model for peripheral nerve distraction in a rat. Primary nerve distraction will need to be subjected to vigorous studies before clinical application.     

Predegenerated nerve allografts versus fresh nerve allografts in nerve repair

This study reevaluated the possibility of using predegenerated nerves as donor nerve allografts for nerve repair and compared the results of functional recovery to those obtained after standard, fresh nerve allograft repair. Twenty donor rats underwent a ligature/ section of the left sciatic nerve 4 weeks before nerve graft harvesting. Forty recipient rats underwent severing of the left sciatic nerve leaving a 15-mm gap between the nerve stumps. Graft repair was undertaken using either the predegenerated left sciatic nerve of the 20 donor rats (predegenerated group, 20 recipient rats) or the normal right sciatic nerve of the 20 donor rats (fresh group, 20 recipient rats). Recovery of function was assessed by gait analysis, electrophysiologic testing and histologic studies. Walking tracks measurements at 2 and 3 months, electromyography parameters at 2 and 3 months, peroperative nerve conduction velocity and nerve action potential amplitude measurements at 3 months, as well as assessments of myelinated nerve fiber density and surface of myelination showed that fresh and predegenerated nerve grafts induced a comparable return of function although there was some trend in higher electrophysiologic values in the predegenerated group. The only slight but significant difference was a larger mean nerve fiber diameter in the nerve segment distal to a predegenerated nerve graft compared to a fresh nerve graft. Although our study does not show a dramatic long-term advantage for predegenerated nerve grafts compared to fresh nerve grafts, their use as prosthetic material is encouraging.     

Stabilization and accurate trimming of nerve ends: practical use of fibrin glue: technical note

OBJECTIVE: Peripheral nerve transection usually results in protrusion of the endoneurial contents ("mushrooming"). Trimming of the nerve ends before repair is often necessary to achieve cut nerve end planes. In this technical report, we describe a technique for stabilization and accurate trimming of nerve ends using fibrin glue. SURGICAL TECHNIQUE: The nerve ends of divided peripheral nerves are coated with fibrin glue and subsequently trimmed using a razor blade before repair. RESULTS: When fibrin glue is applied, a firm layer with a rubbery consistency is formed around the nerve. This layer stabilizes the nerve ends during trimming, and a clear-cut plane of the nerve can be achieved. Moreover, the fibrin glue stabilizes the nerve ends during manipulations caused by suturing of the nerve. CONCLUSION: The technique results in easier handling of the nerve during trimming and manipulation, minimal tissue damage to the nerve, and a clear-cut plane of the nerve.     

Somatotopic redistribution of c-fos expressing neurons in the superficial dorsal horn after peripheral nerve injury

The functional somatotopic reorganization of the lumbar spinal cord dorsal horn after nerve injury was studied in the rat by mapping the stimulus-evoked distribution of neurons expressing proto-oncogene c-fos. In three different nerve injury paradigms, the saphenous nerve was electrically stimulated at C-fibre strength at survival times ranging from 40 h to more than six months: 1) Saphenous nerve stimulation from three weeks onwards after ipsilateral sciatic nerve transection resulted in an increase in the number of Fos-immunoreactive neurons within the dorsal horn saphenous territory in laminae I-II, and an expansion of the saphenous territory into the denervated sciatic territory until 14 weeks postinjury. 2) Saphenous nerve stimulation from five days onwards after ipsilateral sciatic nerve section combined with saphenous nerve crush resulted in an increase in the number of Fos-immunoreactive neurons within the dorsal horn saphenous nerve territory, and an expansion of the saphenous nerve territory into the denervated sciatic nerve territory. 3) Stimulation of the crushed nerve (without previous adjacent nerve section) at five days, but not at eight months resulted in a temporary increase in the number of Fos-immunoreactive neurons within the territory of the injured nerve, and no change in area at either survival time. The results indicate that nerve injury results in an increased capacity of afferents in an adjacent uninjured, or regenerating nerve, to excite neurons both in its own and in the territory of the permanently injured nerve in the dorsal horn. The onset and duration of the increased postsynaptic excitability and expansion depends on the types of nerve injuries involved. These findings indicate the complexity of the central changes that follows in nerve injuries that contain a mixture of uninjured, regenerating and permanently destroyed afferents.     

The influence of MR field strength on the detection of focal liver lesions with superparamagnetic iron oxide

Isolated nerve segments may inherently contain all of the necessary factors required to support regeneration within a silicone tube conduit placed across a nerve gap. Thirty-six adult Lewis rats each weighing approximately 250 g were randomized into three groups. A sciatic nerve gap (13-15 mm in length) was bridged by an empty silicone tube (Group I), a silicone tube containing a short 2-mm interposed nerve segment (Group II), or a nerve autograft (Group III). At 16 weeks postoperatively, no regeneration was observed through the empty silicone tube. In contrast, regeneration across the silicone tube containing the isolated nerve segment was equivalent to that noted through nerve autografts as assessed by histological, electrophysiological, and functional criteria. Thus, an interposed nerve segment will extend the length of successful nerve regeneration through a silicone tube conduit.     

Involvement of delta- and mu-opioid receptors in the potentiation of brain-stimulation reward

Human, dog, cat and rat dental pulps were investigated for the presence and distribution of galanin-like immunoreactive (-IR) nerve fibers, and the possible origin of pulpal galanin-IR nerve fibers in the rat was examined. Galanin-IR nerve fibers were present in the dental pulps of all species examined. Two types of galanin-IR nerve fibers were distinguished with regard to morphology; thin varicose nerve fibers and thick smooth-surfaced nerve fibers. Thin varicose galanin-IR nerve fibers were seen to run along the blood vessel in the human, dog and cat root pulp. In the coronal pulp, galanin-IR nerve fibers ran toward the odontoblastic layer but they did not form the subodontoblastic nerve plexus. In rat molar pulp, few galanin-IR nerve fibers were observed; the distribution of these nerve fibers was similar to those in human, dog and cat pulp. In contrast, many thick smooth-surfaced galanin-IR nerve fibers were observed near the blood vessels in incisor pulp of the rat; occasionally a few varicose galanin-IR nerve fibers were also observed. Transection of the inferior alveolar nerve or mandibular nerve caused complete disappearance of galanin-IR nerve fibers in rat dental pulp, while surgical sympathectomy of the superior cervical ganglion did not affect their distribution. The present results indicate that galanin-IR nerve fibers are present in the mammalian dental pulp, and that the intrapulpal galanin-IR nerve fibers in the rat originate from the trigeminal ganglion and are primary afferents.     

Proximal median and ulnar resections. Results of primary and secondary repairs

PURPOSE OF THE STUDY: Recovery after median and ulnar nerve proximal repair is widely appreciated. The place and time for secondary functional reconstruction remains controversial. MATERIAL AND METHOD: From January 1983 to January 1990, 66 patients suffering from proximal injury of the median or ulnar nerves underwent nerve repair. Forty-five patients had a postoperative follow-up of more than 24 months: 24 isolated ulnar nerve lesions, 12 isolated median nerve lesions, and 9 combined median and ulnar nerve lesions. Ten patients were given a primary microsurgical nerve suture in our department. Thirty-eight patients underwent a delayed or secondary nerve repair of one or both nerves: 8 secondary nerve sutures, and 35 nerve grafts in 31 patients. RESULTS: Muscular strength, sensitivity, motion, and pain were better after primary nerve sutures (when technically possible) or after shortly delayed secondary sutures, although 40 per cent of patients treated with nerve grafts get final "good" or "very good" results. The time between the injury and nerve repair was the most significant prognosis factor. Results of ulnar nerve repairs at the elbow were statistically better with anterior transposition as compared to in situ repairs (p < 0.005). Fourteen patients required secondary functional reconstruction. Tendon transfers were performed at least 24 months after nerve repair. DISCUSSION: Nerve repair of proximal lesion to the median or ulnar nerves depends on the type of injury, but is advised even when delayed. Residual deficit following nerve repair should require functional transfers depending on hand sensitivity and extrinsic function.     

Spatial organization of cortical and subcortical afferent projections of the neostriatum in dogs

Injury to the facial nerve in the temporal bone presents a challenge to the recovery of nerve function, in that the fallopian canal in which it lies is poorly vascularized. This study was designed to determine if wrapping an intratemporal facial nerve defect repaired with a cable graft with a well-vascularized temporoparietal fascial (TPF) flap would improve facial nerve regeneration. To evaluate this question, a defect was created in the intratemporal left facial nerve of 10 rabbits. All nerves were repaired using cable grafts. In 5 animals, the nerve graft was wrapped with temporoparietal fascia, whereas in the other 5 rabbits it was not. Three additional animals underwent exposure only. The contralateral nerve served as a control in all animals. Quantitative analysis of the nerve graft 12 weeks after repair revealed greater recovery of original fiber diameter and myelin sheath thickness in TPF flap-wrapped repairs. Histological evidence of improved neural regeneration and functional nerve recovery was also seen in the repairs where the TPF flap was utilized. Nerve conduction and electromyographic studies of the cable-grafted nerve at 6 and 12 weeks were equivocal, however.     

Classical conditioning of a flexor nerve response in spinal cats: Effects of tibial nerve CS and a differential conditioning paradigm.

Examined, in 4 experiments using 59 cats, the effects of a differential conditioning paradigm on the deep peroneal motor nerve response. Results show that flexor nerve response increases were produced when the conditioned stimulus/stimuli (CS) was delivered to the whole tibial nerve or to the medial plantar branch. The responses to CS/unconditioned stimuli presentations on the superficial peroneal nerve increased, whereas responses to CS presentations on the tibial nerve remained unchanged. However, lack of extinction effects in the superficial peroneal data suggests that stimulation of the tibial nerve potentiated superficial peroneal evoked responses. Furthermore, responses evoked by stimulation of either nerve increased when paired trials were given on the tibial nerve. These data demonstrate that stimulation of the tibial nerve potentiates responses to superficial peroneal nerve stimulation but that superficial peroneal nerve stimulation has no effect on responses to CS presentations to the tibial nerve. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Motor denervation induces altered muscle fibre type densities and atrophy in a rat model of neuropathic pain

Loose ligation of a sciatic nerve in rats (chronic constriction injury; CCI) provokes sensory, autonomic, and motor disturbances like those observed in humans with partial peripheral nerve injury. So far, it is unknown whether these motor disturbances result from (mechanical) allodynia or from damage to the motor neuron. These considerations prompted us to assess, in CCI rats, the density of motor axons in both the ligated sciatic nerve and the ipsilateral femoral nerve. To this end, we determined the number of cholinesterase positive fibres. It has been demonstrated previously that muscle fibre type density may be used as a measure of motor denervation and/or hypokinesia. Therefore, the myofibrillar ATPase reaction was employed to assess fibre type density in biopsies obtained from the lateral gastrocnemius muscle (innervated by sciatic nerve) and rectus femoris muscle (innervated by femoral nerve). We observed axonal degeneration of motor fibres within the loosely ligated sciatic nerve, both at an intermediate (day 21) and at a late stage (day 90) after nerve injury. The reduction in the number of motor nerve fibres was more pronounced distal to the site of the ligatures than proximal. A (less pronounced) reduction of motor fibres was observed in the ipsilateral (non-ligated) femoral nerve. In line with these findings, we observed altered fibre type densities in muscle tissue innervated by the ligated sciatic nerve as well as the non-ligated femoral nerve indicative of motor denervation rather than hypokinesia. The findings of this study suggest that the motor disorder induced by partial nerve injury involves degeneration of motor nerve fibres not only within the primarily affected nerve but also within adjacent large peripheral nerves. This spread outside the territory of the primarily affected nerve suggests degeneration of motor neurons at the level of the central nervous system.     

Intraneural mucous cysts of peripheral nerves

We present three cases of a rare mucous cyst inside the peripheral nerves of the upper extremity; a lateral cutaneous nerve of the forearm, a dorsal sensory branch of the ulnar nerve, and a median nerve at the wrist. All our cases were intraneural, and we excised longitudinal strips of the cyst wall between nerve fascicles in all, preserving nerve function in each case.     

Isolated cranial nerve palsies in multiple sclerosis

During a 10 year period 24 patients with definite multiple sclerosis with isolated cranial nerve palsies were studied (third and fourth nerve: one patient each, sixth nerve: 12 patients, seventh nerve: three patients, eighth nerve: seven patients), in whom cranial nerve palsies were the presenting sign in 14 and the only clinical sign of an exacerbation in 10 patients. MRI was carried out in 20 patients and substantiated corresponding brainstem lesions in seven patients (third nerve: one patient, sixth nerve: four patients, eighth nerve: two patients). Additional abnormal findings of electro-oculography, or masseter reflex, or blink reflex, or combinations of these were found in 20 patients and interpreted in favour of a brainstem lesion at the level of the respective cranial nerve. In 11 of 14 patients with isolated cranial nerve palsies as the presenting sign of multiple sclerosis, dissemination in space was documented by MRI, and in the remaining three by evoked potentials. In patients with multiple sclerosis with isolated cranial nerve palsies, MRI is the most sensitive method of documenting dissemination in space and electrophysiological testing the most sensitive at disclosing brainstem lesions.     

Greater petrosal nerve surgery in long-term cluster headache (author's transl)

Report on three cases with cluster headache for a period of 10 to 20 years, respectively. This was healed by resection of the greater petrosal nerve. In these patients the nerve was found in a bony canal of a length of 5 to 6 mm between the geniculate ganglion and the facial nerve hiatus. In this region the nerve was blurred free, luxated from the canal, and resected. Histological control of this part of the nerve revealed a fibrosis of the peri- and epineurium and a degeneration of some nerve fibers. Histological control in a greater number of cases is recommended.     

The association between different patterns of hand symptoms and objective evidence of median nerve compression: a community-based survey

OBJECTIVE: To examine the association between different patterns of hand symptoms and the presence of delayed nerve conduction in the general population. METHODS: We performed a 2-stage screening survey involving a questionnaire on current hand symptoms, and nerve conduction testing in samples of subjects with and without symptoms. Of 648 respondents to the symptom questionnaire, 212 reported hand symptoms. In all, 155 were tested for nerve conduction of sensory and motor median nerve latencies, including 40 who had reported no symptoms. Patterns of hand symptoms were compared with nerve conduction results and associations weighted back to the general population. RESULTS: The presence of any hand symptoms had only a 40% sensitivity for delayed nerve conduction on latency testing. The presence of typical symptoms of carpal tunnel syndrome had a much lower sensitivity. CONCLUSION: In a community setting, the distribution of hand symptoms does not usefully correlate with the presence of delayed nerve conduction in the median nerve.     

Purification and characterization of fatty acid-binding proteins from brown adipose tissue of the rat

Every nerve must have the capacity to adapt to different positions by passive movement relative to the surrounding tissue. This capacity is called longitudinal excursion (LE). The LE of the sciatic nerve has been studied in 40 Wistar rats. The LE was measured, the nerve was cut, sutured, a metallic body was put into the anastomotic site for later radiographic controls (at the 8th week) and then the anastomosis was protected with different kinds of tissue. After 16 weeks the sciatic nerve was exposed, the LE was measured again and the nerve was dissected out for light microscopy. The LE is produced by two mechanisms: 1) rectification of the undulating course of the nerve and 2) elasticity of the neural connective tissue sheaths. The paraneurim provides a gliding tissue. During flexion movements, it acts as an external support and keeps the nerve under a longitudinal compression force. The normal LE is the release of this compression. These properties enable the nerve to glide without changing its diameter. The gag after nerve section is approximately 75% of LE. After repairing the nerve the new LE is 55% of the original value. In peripheral nerve surgery, to create a new nerve-bed or to protect the anastomoses, a muscle flap should be avoided. On the other hand, no difference could be found between other tissue flaps. When transposing a nerve, the submuscular position is preferable to the intramuscular position.     

The mechanisms of the recovery of nerve ending functions during the reinnervation of skeletal muscle

At the experiments on the frog cutaneous-pectoris muscle the nerve terminal functions in course of reinnervation process were investigated by electrophysiological and morphological methods. At the 20-25th days after the nerve crushing the nerve terminal response, which reflect the nerve terminal currents, formed the propagated action potential, were restored and the arising of evoked transmitter secretion occurred. The regenerating terminals are characterized by a low amplitude and altered shape of responses, by small velocity of the excitation propagation and the low level of evoked transmitter release. The 4-aminopyridine effect at the new formed nerve terminals was quite another, than at the intact nerve terminals. This data concluded, that the membrane of regenerating nerve terminal have a low density and a small gradient of sodium channels along the terminal and have not a calcium-activated potassium channels. It was proposed, that different kinds of channels are inserted into the nerve endings membrane at the different periods of the reinnervation process.     

Blood flow in mobilized nerves: results in a rabbit sciatic nerve model

The purpose of this study was to evaluate the immediate effect on capillary blood flow of surgical mobilization of 15 cm of the rabbit sciatic and tibial nerve. Capillary nerve blood flow was determined with 16-micron radioactive microspheres. Thirty-seven rabbits were divided into six groups. In the control group A (n = 7), the in situ nerve blood flow was determined. In group B (n = 7), the nerve was mobilized, leaving only the proximal and distal endoneurial vascular supplies; blood flow increased compared with in situ values in most segments. In group C (n = 5), the nerve was mobilized as in group B, but also transected distally; blood flow was markedly decreased in the distal segments but was maintained up to a diameter-to-length ratio of 1:63. In group D (n = 6), the nerve was not mobilized, but was transected proximally and distally; blood flow increased in all segments. In group E (n = 5), the nerve was mobilized and transected proximally and distally, leaving only nerve branches intact; blood flow was significantly higher in segments of the nerve from which nerve branches originated with the nerve receiving blood flow through its branches. In group F (n = 6), the nerve was mobilized, all extrinsic vessels except one were transected, and the proximal and distal nerve was transected; flow was maintained to a diameter:length ratio of 1:41 from the source of blood flow. Therefore, it does appear that long lengths of nerve may be mobilized and transposed while maintaining sufficient blood flow.     

A case of mediastinal tuberculous lymphadenitis with tracheal stenosis

The extracellular fluid pathway in the facial nerve and the diffusion of a tracer from the facial nerve to other cranial nerves was examined in the rabbit. Sodium fluorescein solution was injected into either the facial nerve fascicles or the epineurial connective tissue as a tracer at the stylomastoid foramen and then localized by fluorescence microscopy. In the facial nerve, fluorescence was observed in the endoneurium and external nerve sheath (epineurium and perineurium) through the geniculate ganglion following injection into the nerve fascicles. The vestibular, trigeminal, and glossopharyngeal ganglia also showed fluorescence on the injection side in ganglion cells and intercellular connective tissues. The results suggested that the endoneurial connective tissue constitutes a diffusion pathway inside the facial nerve fascicles and that the extracellular fluid pathway from the facial nerve to these cranial ganglia may be related to the neural spread of inflammation or neoplastic metastasis.     

An evaluation of the incisive nerve block and combination inferior alveolar and incisive nerve blocks in mandibular anesthesia

The purpose of this study was to measure the degree of anesthesia obtained with the incisive nerve block, the inferior alveolar nerve block and a combination of both injections in mandibular teeth. Using a repeated measures design, 40 subjects randomly received an incisive nerve block, a conventional inferior alveolar nerve block, or a combination inferior alveolar nerve block plus an incisive nerve block using either lidocaine or saline (control), at four successive appointments. The mandibular teeth and contralateral canine (+/- controls) were blindly tested with an Analytic Technology pulp tester at 4-min cycles for 60 min. An 80 reading indicated complete pulpal anesthesia. The incisive nerve block alone did not result in successful pulpal anesthesia in the central, lateral, first, and second molars. It was successful in the first and second premolars but the duration was approximately 30 min. The combination inferior alveolar nerve block plus incisive nerve block was successful in the first and second premolars, and enhanced anesthesia for the laterals and first molars.     

Study on the intraneural topography of the brachial plexus

An accurate intraneural topography of the nerve fascicules in the brachial plexus provides a correct diagnosis and proper treatment of brachial nerve injuries. Four specimens of the branchial plexus were harvested from human cadavers by careful dissection and serially cross-sectioned from the nerve root level to the peripheral nerve. A spatial relationship between each nerve fascicule was observed and traced proximo-distally with a stereoscopic microscope. The main results and conclusions are as follows: 1. Four types of normal variation were identified in the composing elements of the brachial plexus. It is special interest to note the one in which both the fifth and sixth cervical nerve roots are composed of the dorsal scapular nerve. The existence of normal variations should be taken into account when determining the level and degree of branchial plexus injuries. 2. The nerve fascicules composing each peripheral nerve are most easily discerned at the cord level of the branchial plexus where there are no definite fiber exchanges between those nerve fascicules. These results would indicate that reconstructive nerve operations can be done successfully at the cord level or, at most, at the division level.