Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “NERVES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2005

The efficacy of a nerve stimulator (Cavermap) to enhance autonomic nerve identification and confirm nerve preservation during total mesorectal excision.

PURPOSE: Sexual dysfunction after total mesorectal excision may be caused by injury to the autonomic nerves. During surgery, nerve identification is not always achieved, and, to date, there has been no method to objectively confirm nerve preservation. The aim of this study was to assess the efficacy of a nerve-stimulating device (CaverMap) to assist in the intraoperative identification of the autonomic nerves during total mesorectal excision, and objectively confirm nerve preservation after proctectomy is completed. PATIENTS AND METHODS: Sexually active consecutive male patients undergoing total mesorectal excision were prospectively enrolled in this study. During pelvic dissection, the surgeon attempted to localize the hypogastric and cavernous nerves. CaverMap was used to confirm these findings and to facilitate the identification in cases of uncertainty. At the completion of proctectomy, the nerves were restimulated to ensure preservation. Factors that could affect the surgeon's ability to localize the nerves and CaverMap to confirm this were evaluated. RESULTS: Twenty-nine male patients with a median age of 58 years were enrolled in this study. An attempt to visualize the hypogastric nerves during dissection was made in 26 patients; the surgeon was able to identify the nerves in 19 (73 percent) patients. CaverMap successfully identified the nerves in six of the seven remaining patients, and failed to identify them in only one case. An attempt to localize the cavernous nerves during dissection was made in 13 patients, of which localization was successful in 8 (61.5 percent) patients. CaverMap improved the identification rate in four of the remaining five patients. After proctectomy, CaverMap successfully confirmed the preservation of both hypogastric and cavernous nerves in 27 of 29 (93 percent) patients. A history of previous surgery statistically correlated with failure to identify the hypogastric nerves by the surgeon (P = 0.005). There were no adverse events related to use of the device. CONCLUSION: CaverMap may be a useful tool to facilitate identification of the pelvic autonomic nerves during total mesorectal excision and to objectively confirm nerve preservation.

Autonomic Pathways↗
PubMed1997

Emergence of radial nerve dominance in median nerve cortex after median nerve transection in an adult squirrel monkey.

Throughout the glabrous representation in Area 3b, electrical stimulation of the dominant (median or ulnar) input produces robust, short-latency excitation, evident as a net extracellular "sink" in the Lamina 4 current source density (CSD) accompanied by action potentials. Stimulation of the collocated nondominant (radial nerve) input produces a subtle short-latency response in the Lamina 4 CSD unaccompanied by action potentials and followed by a clear excitatory response 12-15 ms later. Laminar response profiles for both inputs have a "feedforward" pattern, with initial activation in Lamina 4, followed by extragranular laminae. Such corepresentation of nondominant radial nerve inputs with the dominant (median or ulnar nerve) inputs in the glabrous hand surface representation provides a likely mechanism for reorganization after median nerve section in adult primates. To investigate this, we conducted repeated recordings using an implanted linear multi-electrode array straddling the cortical laminae at a site in "median nerve cortex" (i.e., at a site with a cutaneous receptive field on the volar surface of D2 and thus with its dominant afferent input conveyed by the median nerve) in an adult squirrel monkey. We characterized the baseline responses to median, radial, and ulnar nerve stimulation. We then cut the median nerve and semichronically monitored radial nerve, ulnar nerve and median nerve (proximal stump) evoked responses. The radial nerve response in median nerve cortex changed progressively during the weeks after median nerve transection, ultimately assuming the characteristics of the dominant nerve profile. During this time, median, and ulnar nerve profiles displayed little or no change.

Action Potentials↗
PubMedDate not supplied

[Recovery of facial nerve function using sural nerve transplantation after its injury in acoustic nerve surgery].

INTRODUCTION: Statoacoustic n. neurinoma is a benign, slow-growing and usually unilateral tumor. During its growth the tumor exerts pressure on the surrounding anatomic forms within the pontocerebellar angle: cranial nerves, pons, cerebellum. Therefore the first clinical symptoms are ear buzzing and deafness, vision disorders, occipital headache or walking difficulties. The diagnosis of such conditions must be precise, whereas CT (computerized tomography) and MRI (magnetic resonance imaging) are the methods of choice. Surgical tumor removal is the only therapy, but during surgery facial nerve injury occurs. The objective of this paper is a case report of a facial nerve injury and sural nerve transplantation during acoustic neurinoma surgery and recovery of facial nerve function. CASE REPORT: A 23-year-old male patient suffered from ear buzzing in the right ear for a year and a half with gradual development of deafness. Due to frequent headaches and after ophthalmologic examination, the patient was urgently hospitalized at the Neurology Clinic of the Faculty of Medicine in Novi Sad where MRI of the endocranium was performed revealing a tumor of the pontocerebellar right angle, 3 x 3.5 cm in size. The patient has undergone surgery at the Neurosurgery Clinic of the Faculty of Medicine in Pees in Hungary, with suboccipital craniotomy and tumor ablation. During surgery facial nerve injury occurred in the premeatal segment and intraoperative transplantation of sural nerve grafts from the left leg to the distal parts of the facial nerve was performed. The histopathologic finding revealed an acoustic neurinoma (Schwannoma). After surgery a control CT was performed revealing a complete tumor removal. The wound healed per primam intentionem and the patient was released from hospital two weeks later. During the postoperative period physical therapy was performed in the aim of rehabilitation of the facial nerve due to peripheral paralysis. After electrodiagnostic tests using GALVOMED 20 apparatus, massage was performed in the periorbital and perioral regions. Kinesitherapy was also done in front of a mirror several times a day. 6 months after surgery an EMG (electromyography) of m. frontalis dx., m. orbicularis oculi dx. and m. orbicularis oris dx. were performed. The EMG revealed evident reinnervation possibilities. A year after surgery the control MR finding of the endocranium was regular, as well as the control MR two years after surgery (postoperative cyst without signs of recurrence of the removed neurinoma). Control EMG of the m. frontalis dx., m. orbicularis oculi dx., m. orbicularis oris dx. showed signs of reinnervation. DISCUSSION: Tumors of the pontocerebellar angle are usually acoustic nerve neurinomas. 8% of intracranial tumors are Schwannomas. They originate from neurilemmal cells, by rule they grow slowly and are benign tumors. Therefore, for years the only signs pointing to them are ear buzzing and gradual development of deafness. That is why these anamnestic data are important for diagnosis. Headaches, walking difficulties, vision disorders are the usual difficulties due to which patients seek doctor's help. Computerized tomography and magnetic resonance imaging represent the diagnostic methods of choice in establishing the diagnosis. In this case MRI was performed on time. Surgery is the only therapy, but during tumor ablation the facial nerve was injured in the premeatal region. Intraoperative transplantation of grafts taken from sural nerve to proximal and distal parts of the facial nerve provides possibilities for injured nerve regeneration. The process of regeneration of such a nerve is long-term and often permanent 40% axon loss occurs. This is the reason to perform a control EMG two years after surgery. During peripheral paralysis rehabilitation is performed in the aim of preventing contractures. It is achieved by passive exercises in front of a mirror a few times a day. (ABSTRACT TRUNCATED)

Adult↗
PubMed2002

Nerve transfer for treatment of brachial plexus injury: comparison study between the transfer of partial median and ulnar nerves and that of phrenic and spinal accessary nerves.

OBJECTIVE: To compare the effect of using partial median and ulnar nerves for treatment of C(5-6) or C(5-7) avulsion of the brachial plexus with that of using phrenic and spinal accessary nerves. METHODS: The patients were divided into 2 groups randomly according to different surgical procedures. Twelve cases were involved in the first group. The phrenic nerve was transferred to the musculocutaneous nerve or through a sural nerve graft, and the spinal accessary nerve was to the suprascapular nerve. Eleven cases were classified into the second group. A part of the fascicles of median nerve was transferred to be coapted with the motor fascicle of musculocutaneous nerve and a part of fascicles of ulnar nerve was transferred to the axillary nerve. The cases were followed up from 1 to 3 years and the clinical outcome was compared between the two groups. RESULTS: There were 2 cases (16.6%) who got the recovery of M4 strength of biceps muscle in the first group but 7 cases (63.6%) in the second group, and the difference was statistically significant (P<0.025). However, it was not statistically different in the recovery of shoulder function between the two groups. CONCLUSIONS: Partial median and ulnar nerve transfer, phrenic and spinal accessary nerve transfer were all effective for the reconstruction of elbow or shoulder function in brachial plexus injury, but the neurotization using a part of median nerve could obtain more powerful biceps muscle strength than that of phrenic nerve transfer procedure.

Adolescent↗
PubMed2006

[Applied anatomic study on the repair of the facial nerve defect by the anastomosis of the facial nerve with the phrenic nerve].

OBJECTIVE: To explore of the anatomic basis of the anastomosis of the facial nerve with the phrenic nerve. METHOD: Bilateral microsurgical dissection was performed on eleven human cadavers fixed with formalin. The following length data were measured with calipers: the distance between the bifurcation of the facial nerve trunk and the phrenic nerve root, the useful length of the facial nerve trunk and the phrenic nerve, and the distance between the overlapped nerve ends. RESULT: The length from the root of the the phrenic nerve to the level of the subclavian vein was (7.2 +/- 1.6) cm. The length from the root of the phrenic nerve to the bifurcation of the facial nerve trunk was (7.23 +/- 0.9) cm. The length from the bifurcation of the facial nerve trunk to the level below the horizontal semicircular canal was 2.7-3.5 cm, 1.0-1.5 cm longer than that cut below the level of the stylomastoid foramen. The cutting nerve ends were placed side by side. The distance between the overlapped nerve ends was 0.4-1.8 cm. CONCLUSION: In 20 specimens the tension-free anastomosis of the facial nerve with the phrenic nerve that cut in the subclavian vein level can be achieved, in 2 specimens the tension-free anastomosis can not be achieved.

Adult↗
PubMed2004

Sensory nerve conduction of the plantar nerve compared with other nerve conduction tests in rats.

OBJECTIVE: In rats the available techniques for evaluation of sensory nerve conduction are limited. We report a new method of sensory nerve conduction of the plantar nerve using needle electrodes as the recording electrodes behind the medial malleolus and ring electrodes as the stimulating electrodes around the three middle toes. METHODS: We performed this sensory nerve conduction test in 25 rats during their growth over a 6 weeks' period and compared this method with the motor nerve conduction and H-reflex sensory nerve conduction of the tibial nerve in 10 rats, and with the motor and mixed nerve conductions of the tail nerve in 15 rats. RESULTS: There was a highly or moderately significant correlation between the body weight and sensory nerve conduction velocity (NCV) of the plantar nerve, mixed NCV and motor NCV of the tail nerve, indicating a growth-related increase in the NCV. The growth-related increase in the NCV was not observed in the motor and H-reflex sensory nerve conductions of the tibial nerves. CONCLUSIONS: This test is simple and reliable and can be used for the sensory nerve conduction test in rats.

Aging↗
PubMed2002

Laryngeal recurrent nerve injury in surgery for benign thyroid diseases: effect of nerve dissection and impact of individual surgeon in more than 27,000 nerves at risk.

OBJECTIVE: To evaluate the effect of recurrent nerve dissection on the incidence of recurrent laryngeal nerve injury (RLNI) and to analyze the performance of individual surgeons. SUMMARY BACKGROUND DATA: Dissection of the recurrent nerve is mandatory in total thyroidectomy, but its relative merit in less extensive resections is not clear. The reported rates of RLNI differ widely; this may reflect a variation in the performance of individual surgeons. METHODS: The authors studied the incidence of RLNI in primary surgery for benign thyroid disease during three periods in a single center. In period 1 (1979-1990; 9,385 consecutive patients, 15,865 nerves at risk), the recurrent nerve was not exposed. In period 2 (1991-1998; 6,128 patients, 10,548 nerves at risk), dissection of the recurrent nerve was the standard procedure. Global outcome and individual performance in these two periods were compared and presented to the surgeons. The effect of this quality control procedure was tested in 1999 (period 3; 930 patients, 1,561 nerves at risk). RESULTS: Exposure of the recurrent nerve significantly reduced the global rate of postoperative and permanent RLNI. Some but not all surgeons improved their results by recurrent nerve dissection (e.g., permanent RLNI rates ranged from 0% to 1.1%). The documented significant differences in individual performances did not affect the outcome in period 3. The extent of nerve dissection was a source of variability; the rate of permanent RLNI averaged 0.9%, 0.3%, and 0.1% for surgeons who only localized, partially exposed, and completely dissected the recurrent nerve, respectively. CONCLUSIONS: Recurrent nerve dissection significantly reduces the risk of RLNI. Extensive dissection facilitates visual control of nerve integrity during resection and is therefore superior to a more limited exposure of the nerve. Quality control can improve the global outcome and identify the variability in individual performance. This cannot be eliminated by merely confronting surgeons with comparative data; hence, it is important to search for the underlying causes.

Adolescent↗
PubMed1991

Nerve regeneration through a two-ply biodegradable nerve guide in the rat and the influence of ACTH4-9 nerve growth factor.

Biodegradable polyurethane-based (PU) nerve guides, instilled with or without ACTH4-9 analog (a melanocortin) were used for bridging an 8 mm gap in the rat sciatic nerve and were evaluated for function and histological appearance after 16 weeks of implantation. Autologous nerve grafts functioned as controls. The guides successfully enabled the sciatic nerve to regenerate across the 8 mm gap, thus effectively reestablishing the contact between the proximal and distal nerve ends. The mean conduction velocity, motor latency, and muscle action potentials of all the nerve guides did not differ significantly from the autografts. The histological quality of the regeneration in the nerve guides was significantly better than in the autografts; in the nerve guides, a well-defined nerve cable of normal architecture had regenerated without extensive endoneural scarring as seen in the autografts. ACTH4-9 instilled in the nerve guides showed a slight, but significant, increase in the number of myelinated axons. It is concluded that biodegradable PU nerve guides result in similar functional recovery when compared with autografts, but their histological quality is significantly better. ACTH4-9 showed only slight, but significant, improved nerve growth promoting activity. Therefore biodegradable PU nerve guides with ACTH4-9 would appear to be promising alternatives to autografts for bridging nerve defects.

Adrenocorticotropic Hormone↗
PubMed2005

Nerve regeneration through a healthy nerve trunk: a new and hopeful conduit for bridging nerve defects.

BACKGROUND: Considering a healthy nerve trunk as the hypothetically ideal conduit, a new experimental model using an intact nerve for bridging a nerve defect was contemplated. METHODS: Thirty rats were used. In group I (double coaptation), a segment was removed from the peroneal nerve. Both the proximal and distal stumps were repaired end-to-side to the tibial nerve. In group II (only distal coaptation), only the distal nerve stump was repaired. In group III (control), the transected segment was immediately repaired primarily in its original orientation as a nerve graft. A walking track analysis was conducted periodically for 28 months. The horseradish peroxidase retrograde labeling technique was used for tracking the origin of the axons presented in the distal stump of the peroneal nerve in group I, and morphologic studies were also carried out for all the groups. RESULTS: Functional assessment revealed that the difference between group I and group II was significant. The horseradish peroxidase labeling test suggested that the nerve fibers in the distal stump of the peroneal nerve were mostly from its original proximal stump passed by the way of the tibial nerve bridge. CONCLUSION: This study suggested that the axons of the proximal stump of a sectioned nerve can sprout into another intact nerve trunk by the way of an end-to-side repair site, regenerate, and advance in its epineurium distally for a distance and pass into its original distal stump if it was repaired end-to-side. It was thought that the technique could be used in clinical cases with short nerve defects as an alternative method to grafts and conduits.

Anastomosis, Surgical↗
PubMed2001

Interleukin-6 and nerve growth factor levels in peripheral nerve and brainstem after trigeminal nerve injury in the rat.

Earlier studies have demonstrated that inflammation plays a role in the development of evoked pain following partial nerve injury. In this report, we demonstrate bilateral changes in interleukin-6 (IL-6) and nerve growth factor (nerve growth factor) levels following unilateral infraorbital nerve (infraorbital nerve) constriction. infraorbital nerve constriction resulted in an initial period of decreased mechanical sensitivity (1 and 3 days), followed by recovery (7 days) and then a marked bilateral mechanical hypersensitivity (10 and 28 days). nerve growth factor levels in the injured infraorbital nerve were elevated on all days, but peak concentrations of nerve growth factor were observed on day 3. A smaller increase was also observed on days 1, 3, and 7 in the uninjured nerve. A bilateral elevation of IL-6 was also seen on days 3 and 10 in the infraorbital nerve, and in the brainstem on days 3, 7 and 10 after constriction. No changes in mechanical sensitivity were found after a sham-injury, but there was a small increase in brainstem IL-6 ipsilaterally at 7 days. We conclude from these data that increases in IL-6 and nerve growth factor may contribute to the development of mechanical allodynia after trigeminal nerve injury, but they are not specifically correlated with the onset or duration of pain behaviors.

Analysis of Variance↗
PubMed1990

Spinal nerve root origin of the median, ulnar and musculocutaneous nerves and their muscle nerve branches to the canine forelimb.

The contribution individual ventral spinal nerve roots made to the canine median nerve, ulnar nerve, musculocutaneous nerve, and their muscle nerve branches was determined electrophysiologically. Each spinal nerve root was sequentially stimulated. Utilizing quantitative signal averaging techniques, the evoked potential was measured at each tested peripheral nerve. Evoked potential to the median nerve originated from the seventh cervical spinal root (C7) through the second thoracic spinal root (T2) with most input from C8 and T1. The ulnar nerve received evoked potential from C7-T2. Although T1 provided the major input to both the median and ulnar nerves, the relative contribution of T1 was greater in the ulnar nerve. The musculocutaneous nerve received input from ventral spinal roots C6-T1 with C6 and C7 providing most of the evoked potential. The ventral spinal roots which supplied the bulk of the evoked potential to a particular muscle nerve were consistent between individual dogs. Variation of evoked potential input was greatest from spinal roots which supplied less than 10% of the total potential.

Animals↗
PubMed2000

Modulation of peripheral nerve regeneration: a tissue-engineering approach. The role of amnion tube nerve conduit across a 1-centimeter nerve gap.

A new type of a biodegradable nerve graft conduit material, the amnion tube, has been developed in our laboratory. To test the tube in the peripheral nerve regeneration process, it was initially applied across a 1-cm sciatic nerve gap in rats and was compared with other nerve conduit materials. We used male Sprague-Dawley rats as our animal model. The experiment included 66 rats that were randomly assigned into five groups: autograft (n = 17), amnion tube (n = 19), silicone tube (n = 20), no repair (n = 7), and sham group (n = 3). The process of peripheral nerve regeneration was evaluated at 2, 4, 10, and 17 weeks following injury and repair by using morphologic and functional assessments of the outcome of nerve regeneration in each animal. Nerve regeneration across the amnion tube nerve conduit was comparable with that seen in autograft and superior to that of the silicone group. A uniform nerve tissue was seen filling and crossing the amnion conduit, and the regenerated nerve from the proximal stump reached the distal end and was undifferentiated from the normal nerve tissues. At 4 months, the amnion tube biodegraded and no longer could be identified and differentiated from the nerve tissues. The amnion tube animal group showed a number of axons very close to that in the nerve autograft group (37,157 versus 33,054). Functional recovery at a 2- to 4-week interval was significantly statistically higher only in the amnion tube animal group (p = 0.01). However, the improvement disappeared between 10 and 17 weeks. In conclusion, the amnion tube is a potential ideal nerve conduit material secondary to its unique characteristics: it contains important neurotropic factors, is biodegradable, provokes a very weak immune response, is semiflexible, is readily available, and is easily manufactured into different sizes and diameters.

Amnion↗
PubMed1989

Peripheral nerve pathological findings in familial amyloid polyneuropathy: a correlative study of proximal sciatic nerve and sural nerve lesions.

To analyze the peripheral nerve pathological abnormalities in familial amyloid polyneuropathy, a correlative pathological study was carried out on the spinal nerve roots, proximal sciatic nerves, sural nerves, and brachial plexuses from 3 patients with the disease in Japan. The spinal nerve roots appeared to be unaffected except for amyloid deposition on the epineurium. In sciatic nerves and brachial plexuses the nerve lesions had a multifocal distribution, showing prominent interstitial edema in the endoneurium frequently adjacent to deposits of amyloid; in these regions the nerve fibers were severely depleted. A teased-fiber study revealed that segmental demyelination was the predominant type of nerve fiber abnormality. However, these findings were not seen in the sural nerves; instead a diffuse fiber loss with axonal degeneration was observed. It is suggested that multifocal lesions in the proximal portions of the long extremity nerves could summate distally to produce a symmetrical polyneuropathy in the disease. In addition to a space-occupying effect of amyloid deposits in the endoneurium, severe endoneurial edema associated with amyloid deposition in blood vessels and the endoneurial interstitium may induce ischemia in nerve fibers, thus causing the progressive polyneuropathy in this disorder.

Adult↗
PubMed2004

Distal nerve elongation vs nerve grafting in repairing segmental nerve defects in rabbits.

Segmental nerve defects have been repaired with nerve grafts. However, regenerating fibers must go through two coaptation sites, and donor site morbidities are inevitable. We elongated the distal nerve segment using a tissue expander and reconnected the nerve. We compared these results with those of nerve grafting. Nerve injury models were created in the median nerves of both forelimbs in 27 rabbits. The right nerve was repaired by elongation, and the left by tibial nerve grafting. The length of the elongation was the same as that of the graft in each animal. Eight rabbits had a 10-mm segment repaired, 9 had a 15-mm segment repaired, and 10 had a 20-mm segment repaired. Evaluated outcomes were nerve conduction velocity, contractile force of the flexor muscle, axons number, and fiber diameter. The elongated and grafted groups did not differ substantially on any outcome. Distal nerve elongation could be an alternative to nerve grafting for repairing large nerve defects.

Analysis of Variance↗
PubMed1997

[Anatomical study and clinical application of transfer of pronator quadratus branch of anterior interosseous nerve in the repair of thenar branch of median nerve and deep branch of ulnar nerve].

In order to obtain the anatomical basis of transferring the anterior interosseous nerve to repair the injury of thenar or ulnar nerve at the wrist level, ten fresh cadaveric forearms were dissected. The pronator quadratus branch of the median nerve was (1.5 +/- 0.4) mm in diameter with (866 +/- 144) nerve fibers. The recurrent branch of median nerve was (1.7 +/- 0.3) mm in diameter with (1,120 +/- 97) nerve fibers. The deep branch of ulnar nerve was (2.1 +/- 0.4) mm in diameter with (1,318 +/- 120) nerve fibers. To repair the thenar recurrent branch, nerve graft should be used to bridge between the distal end of the anterior interosseous nerve and the origination of the recurrent branch. The deep branch of the ulnar nerve could be repaired by direct suture after being dissected proximally. In patients, the technique was applied to repair 17 cases of injury of thenar branch and 3 cases of injury of deep branch of ulnar nerve. Among them, seventeen cases were followed up from 2 to 7 years. On electromyogram it was normal in 10. The myodynamia was restored in different degree: M2 in 2, M3 in 5, M4 in 7, M5 in 3. The procedure of the operation and the matters needed attention during the operation were discussed.

Adolescent↗
PubMed1982

Peripheral nerve phospholipid composition: development in normal nerve and age-dependent changes in Wallerian degenerated nerve.

The phospholipid composition of normal peripheral nerve as a function of developmental age as well as that of Wallerian-degenerated nerve as a function of age at nerve transection and duration of Wallerian degeneration have been quantitated in rabbit sciatic nerve. During development, increases in the proportions of ethanolamine plasmalogen, sphingomyelin, and combined phosphatidyl serine plus phosphatidyl inositol and decreases in the proportions of phosphatidyl choline and phosphatidyl ethanolamine correlated well with the concurrent myelin accretion. During Wallerian degeneration, age-dependent changes in phospholipid composition were observed. The large and statistically significant increase in the proportion of phosphatidyl choline and decrease in the proportion of ethanolamine plasmalogen were manifest promptly in nerves transected at 2 weeks of age but in a delayed manner in nerves transected at 8, 12, and 20 weeks of age. The rate of loss of individual phospholipids was greater in nerves transected at younger ages. The findings from normal developing peripheral nerve may well serve as baseline data for subsequent studies of phospholipid composition in pathological peripheral nerve. The findings from Wallerian-degenerated peripheral nerve provide additional evidence for age-dependent chemical changes occurring in Wallerian-degenerated peripheral nerve that may be of significance in explaining the superior functional recovery from peripheral nerve injury observed in younger compared with older subjects.

Aging↗
PubMed1982

Tropism in nerve regeneration in vivo. Attraction of regenerating axons by diffusible factors derived from cells in distal nerve stumps of transected peripheral nerves.

We re-examined the hypothesis of Cajal3, later refuted by Weiss and Taylor20, that cells in distal stumps of transected peripheral nerves exert an attractive (tropic) effect on regenerating axons. This question was re-assessed in vivo using surgical materials and assay procedures not available to those workers. Proximal stumps of transected rat sciatic or cat peroneal nerves were inserted into the single inlet end of a hollow, Y-shaped Silastic implant. Regenerating axons were provided with alternative targets consisting of a vacant arm vs one occupied by a sciatic nerve graft (rat), or a tibial (Tout) vs peroneal (Pout) distal nerve stump (cat). In some cases Pout was rendered metabolically compromised relative to Tout by exposing the former to dry ice and inhibitors of DNA and RNA synthesis. At 4.5 or 6 weeks postoperatively, the number of regenerating axons in each fork of the implant was assessed by morphometric analysis (total number of non-myelinated and myelinated axons greater than 1 micron in diameter at 4.5 weeks, and total number of myelinated axons at 6 weeks postoperatively), or by quantification of an axonally transported label. Rat sciatic nerve fibers exclusively regenerated toward the nerve graft, suggesting the existence of a neurotropic lure. In cats, morphometric analysis revealed a 10-(4.5 week) and 6-fold (6 week) greater number of axons growing towards untreated Tout vs treated Pout. When both distal stumps were untreated, more axons were seen in forks leading to Pout. Analysis of transported label confirmed the preferential growth of axons towards untreated Tout vs treated Pout for both motor and sensory axons. In separate experiments, Nuclepore filters (0.2 microns, pore size) were inserted between distal nerve stumps and outlet ends of Silastic implants. Preferential regeneration toward untreated stumps was observed if the distance between proximal and distal nerve stumps was equal to but not greater than 4-5 mm. These results suggest that peripheral nerve fiber regeneration in vivo can be directed by cells in distal stumps of transected nerves, and that this effect can be mediated over distances of several millimeters via diffusible factors.

Animals↗
PubMed1999

Anesthetic efficacy of the mylohyoid nerve block and combination inferior alveolar nerve block/mylohyoid nerve block.

OBJECTIVE: The purpose of this study was to measure the degree of anesthesia obtained with the mylohyoid nerve block and the combination mylohyoid nerve block/conventional inferior alveolar nerve (IAN) block in mandibular teeth. STUDY DESIGN: With the use of a repeated-measures design, 30 subjects randomly received each of 3 combinations of injections at 3 separate appointments. The combinations were as follows: mylohyoid nerve block (1.8 mL of 2% lidocaine with 1:100,000 epinephrine) + IAN block (3.6 mL of 2% lidocaine with 1:100,000 epinephrine); mock mylohyoid nerve block + IAN block (3.6 mL of 2% lidocaine with 1:100,000 epinephrine); mylohyoid nerve block (1.8 mL of 2% lidocaine with 1:100,000 epinephrine) + mock IAN block. The mylohyoid injections were aided by the use of a peripheral nerve stimulator. Mandibular anterior and posterior teeth were blindly tested with a pulp tester at 4-minute cycles for 60 minutes postinjection. Anesthesia was considered successful when 2 consecutive 80 readings were obtained. RESULTS: One hundred percent of the subjects had lip numbness with the mylohyoid nerve block + IAN block and mock mylohyoid nerve block + IAN block techniques. For these 2 techniques, anesthetic success rates were higher in posterior teeth (73% to 93%) than in anterior teeth (33% to 60%). There were no significant differences (P > .05) between the 2 techniques. The mylohyoid nerve block + mock IAN block technique resulted in a very low success rate (0% to 17%) and was significantly different (P < .05) from the mylohyoid nerve block + IAN block technique. CONCLUSIONS: The results of this study suggest that the mylohyoid nerve block does not by itself predictably provide pulpal anesthesia in mandibular teeth and does not significantly enhance pulpal anesthesia when administered in combination with the IAN block.

Adult↗