[The asymptomatic thoracic outlet compression syndrome]. / Das asymptomatische Thoracic-outlet-Kompressionssyndrom.

The thoracic outlet compression syndrome has a great number of clinical variations. Arterial and venous perfusion impairment is an associated symptom, nerve irritation can occur with or without vascular problems. The degree of nerve damage ranges from transient irritation to permanent motoric and sensory defects. The lack of space in the supracostoclavicular compartment is the cause for nerve compression. The degree of neural damage depends on the degree and duration of the compression. Anatomic variations between the clavicle and first rib are frequent causes for the TOS: accessory ribs and muscles, and fibrous bands have been described. A preexisting chronic compression may lead to a subclinical TOS, in this case an inadequate trauma of minor degree may be sufficient to manifest a plexus palsy. Intraoperative findings in children with incomplete and complete brachial plexus palsy and the corresponding findings in adults prompted us to present this communication.

[Intraoperative histological sections in obstetric brachial plexus lesions--comparison of macroscopic appearance, HE staining and toluidine blue staining]. / Intraoperative Schnellschnittdiagnostik bei der geburtstraumatischen Plexusläsion - Gegenüberstellung von Makroskopie, HE-Schnellschnitten und Semidünnschnitten mit Toluidinblau-Färbung.

In brachial plexus lesions and their revision, evaluation of nerve stumps is very important for the reconstructive strategy. We intraoperatively perform cryostat sections, Haematoxilin-Eosin (HE) stained, and compare the clinical appearance of the nerves to the microscopic results. Toluidine blue staining is later used to validate the structural details. Intraneural fibrosis can be traced safely with both staining methods, in root avulsions a histology is helpful, too. For more proximal, intraforaminal lesions semithin section stained with toluidine-blue are less informative than are HE-stained cryostat sections. In these lesions the clinical control by electrical stimulation and evoked potentials is superior.

[Reconstruction of defects at the neuromuscular junction]. / Rekonstruktion bei Defekten im neuromuskulären Ubergang.

Loss of muscle tissue at the area of the neuromuscular junction after tumor resection or after trauma precludes the reconstruction with conventional nerve grafts, because the distal nerve stump is absent. For these cases, we recommend direct insertion of the nerve grafts into the muscle. We describe a standardized technique, which has been performed in 19 patients and led to a mean motor recovery of grade M4 after Highet. The key procedure of this technique is the interfascicular dissection of the nerve grafts, which allows a wide distribution of the grafts into the muscle tissue.

The cervical rib. A predisposing factor for obstetric brachial plexus lesions.

Controversy surrounds the aetiology of obstetric brachial plexus lesions. Most authors consider that it is caused by traction or compression of the brachial plexus during delivery. Some patients, however, present without a history of major traction during delivery, and some delivered by Caesarean section also suffer the injury. In our series of 42 infants, 28 had an Erb's palsy, and the remaining 14 presented with a more extensive lesion, involving the lower roots. In five of these, a complete ossified cervical rib was found. We believe that anatomical variations, such as cervical ribs or fibrous bands, can cause narrowing of the supracostoclavicular space, and render the adjacent nerves more susceptible to external trauma.

[Therapy of soft tissue trauma in the acute phase of severe hand injuries]. / Therapie des Weichteiltraumas in der Akutphase von schweren Handverletzungen.

INTRODUCTION: Complex hand injuries are characterized by a combination of soft tissue injury and additional trauma to functional structures such as nerves, bones, tendons, vessels and joints. A good functional result requires the reconstruction of the injured structures and early mobilisation. Good vascularized soft tissue and stable osteosyntheses are the major prerequisites to avoid infections and to allow early mobilisation. The optimal timing for soft tissue reconstruction remains controversial with respect to the incidence of infections. METHODS: We have evaluated retrospectively our series of complex hand injuries addressing the question whether a delay of soft tissue coverage for up to 72 hours causes significant increase of infection rates. RESULTS: 48 patients were treated with complex injuries of the hand within a three year period between December 1998 and December 2000. The lowest incidence of infections occurred in the group, where soft tissue coverage was completed as an emergency procedure. DISCUSSION: Ideally primary reconstruction of complex hand injuries should be strived for to minimize scar formation as a result of secondary operations and further immobilisation periods. This includes, if necessary, free tissue transfer. Exceptions are situations where the vitality of soft remains uncertain. In these cases, definitive surgery is delayed for a maximum period of 72 hours.

Cellular activity of resident macrophages during Wallerian degeneration.

The resident macrophages have been accepted as an important component of the peripheral nervous system as Schwann cells. To elucidate their role during Wallerian degeneration without interference from extrinsic hematogenous macrophages, we designed a culture system to investigate the behavior of resident macrophages in vitro. A total of 75 adult male Lewis rats were used; 2. 5-cm-length sciatic nerve explants were harvested. There were three groups. In the culture groups, the nerve explants were incubated in Dulbecco's modified Eagle's medium (DMEM) only or in DMEM supplemented with 2 microm forskolin and 10 microg/ml pituitary extract (mitogenic medium for Schwann cells). In vivo predegenerated nerves and normal nerves were used as the positive and negative controls, respectively. The observation periods extended to 3 weeks. Hematoxylin and eosin (H&E) stain was employed to estimate overall cell number in nerve explants. Macrophages were labeled with ED1; S-100 immunostaining was used to evaluate the presence of Schwann cells during Wallerian degeneration. Trichrome stain and toluidine blue stain were used to visualize the fate of myelin. In the culture groups, the number of resident macrophages increased continuously, although there were significantly fewer resident macrophages than hematogenous macrophages after 3 days of Wallerian degeneration (P < 0.01). Morphologically, resident macrophages contained densely small ED1-positive granules within their cytoplasm, even at later stages of observation, whereas hematogenous macrophages contained typical large ED1-positive foam vacuoles characteristic of their mature phagocytic ability. The cellular activity of Schwann cells was well preserved in the mitogenic medium; however, myelin removal was not significantly enhanced as compared with the DMEM groups (P > 0.05). The clearance of myelin debris was shown to be incomplete in culture groups as compared with the complete removal of myelin debris in the in vivo groups. Resident macrophages were actively involved in Wallerian degeneration, but their phagocytic and proliferation ability was limited. Schwann cells played an adjunctive role during the removal of myelin debris.

Cryopreservation of peripheral nerve grafts.

The utilization of viable biological nerve graft substitutes and nerve allografts raises the problem of nerve storage. To clarify this, rat sciatic nerve segments were harvested and stored in Dulbecco's modified eagle medium. The segments were divided into three groups. In the first group, no cryoprotectant was added, whereas the second had 10% dimethyl sulfoxide (DMSO) added as cryoprotectant. These two groups of nerve segments were subjected to controlled freezing. In a third group, segments were frozen uncontrolled in liquid nitrogen (-196 degrees C). All nerves were replanted orthotopically. Fresh conventional autografts (fourth group) served as control group. Histologically, freezing did not affect the structural elements such as basal lamina tubes and perineurial tissue. Morphometrically, all cryopreserved grafts had significantly reduced axon counts and less myelinization than did controls. Cryoprotected nerves (group 2) showed no different morphometric parameters compared with the group without DMSO (group 1). Controlled freezing was superior to uncontrolled freezing (group 3). Impaired regeneration was attributed mainly to delayed Wallerian degeneration and slower revascularization. Moreover, decreased survival of resident Schwann cells in the graft may impair regeneration due to the lack of neurotrophic, neurotropic, and attachment factors in early regeneration. Grafts subjected to controlled freezing support axonal regeneration to a certain extent, but further studies are required to assess various cooling patterns, cryoprotectants, and graft revascularization.

Viability of cultured nerve grafts: An assessment of proliferation of Schwann cells and fibroblasts.

Previous studies demonstrated that the viability of nerve grafts had a positive effect on nerve regeneration, while the cold storage of nerve grafts obtained few viable cells at the later stage. The purpose of this study was to examine the cellular activities of Schwann cells and fibroblasts in cultured nerve grafts prior to transplantation. 2.5-cm long sciatic nerve grafts were harvested from 75 male Lewis rats. Two different media were utilized to culture the nerve grafts up to 3 weeks: Dulbecco's modified eagle medium (DMEM) only or DMEM supplemented with 2 microM forskolin and 10 microg/ml pituitary exact (mitogen medium for Schwann cells). In vivo predegenerated and normal nerve grafts were used as positive and negative controls, respectively. We employed a 5-bromo-2'-deoxyuridine (BrdU) incorporation method to evaluate the proliferating cells in the cultured nerve grafts. S-100 and vimentin immunostaining were used to estimate the presence of Schwann cells and fibroblasts in all nerve grafts at different intervals. The results showed that the proliferating cells increased progressively under culture conditions. The proliferating cells distributed evenly in small fascicles (average diameter 251 +/- 71.5 microm), whereas they appeared mainly in the margin of large fascicles (average diameter 624 +/- 87.3 microm). The mitogen medium stimulated Schwann cell multiplication more significantly in comparison with DMEM after 3 days of culture (P < 0.01), however, there were fewer fibroblasts present in the mitogen medium than in DMEM after 2 days of culture (P < 0.01). It is suggested that the viability of nerve grafts can be preserved under culture conditions. Furthermore, the cellular activity of the Schwann cells and fibroblasts in nerve grafts can be manipulated in in vitro Wallerian degeneration.

[Surgical replantation]. / Replantationschirurgie.

In the early days of replantation surgery, if viability was restored the operation was judged a success. Nowadays restoration of viability alone is not sufficient to fulfill the criteria of successful replantation, which are as follows: Lack of severe systemic disturbances due to the replantation, a "functional extremity" according to the definition of Chen et al. (1978), no or little pain at the site of the replantation, good aesthetic results, and an acceptable length of time for rehabilitation and return to normal life. Successful replantation needs a therapy concept that is based on an exact definition of the amputation injury from the viewpoint of the amount of severance, the level of the amputation, and the type of amputation mechanism, complete knowledge of current replantation indications, and exact selection of patients amenable for replantation.

Timing of free microsurgical tissue transfer for the acute phase of hand injuries.

Because of favourable survival rates in replantation surgery and a high standard of free tissue transfer the interval between injury and microsurgical reconstruction has become gradually shorter. The acute phase can be defined as the interval ranging from emergency procedures within 24 hours to urgent procedures done within 72 hours. Bearing in mind the infection rates that have been reported of 1.5% for the acute phase and 17.5% for the late phase, we should encourage emergency reconstructions. However, in most cases of upper extremity injuries, reconstruction with conventional flaps is possible. Between 1981 and 1995 we did 72 acute post-traumatic free tissue transfers to the upper extremity in our unit within 72 hours (urgently). There were no significant differences in the incidence of infections when acute were compared with urgent procedures. As a result we support the concept of urgent operations. The following advantages are to be considered: urgent operations allow a second look operation, the viability of the extremity can be assessed, and the reconstructive procedure can be planned more precisely. Last but not least, the procedure is done during the day time with better operating conditions.

Replantation of the complete external genitals.

Most cases of genital amputation represent an isolated penile amputation; the combined amputation of both penile and testes is reported very seldom. We describe a case of complete amputation of the external genitals with successful replantation and good functional outcome. The problem is analyzed with respect to operative strategy, ischemic periods, postoperative management, and psychiatric background. For the replantation of the testes, time frames are comparable to those for macroreplantations.

[Time limited immunosuppression in allogenic nerve transplant in the rat]. / Die zeitlich begrenzte Immunsuppression am allogenen Nerventransplantat der Ratte.

A rejection response of peripheral nerve allografts eliminates the Schwann cells without destroying the tubular architecture and leads to a regeneration of inferior quality. Under immunosuppression this rejection is prevented, and allogenic Schwann cells persist in the grafts, leading to a better regeneration result. In adult rats of the strains DA and LEW.1W, a 2,5 cm segment of the sciatic nerve was grafted. Under Cyclosporin A regeneration was allowed to take place for 12 weeks. Thereafter, immunosuppression was discontinued in one group and gradually reduced in another. Regeneration quality was compared after an additional six weeks in comparison to an autologous control. Best regeneration was observed in the autologous control; no statistical differences were observed between the two experimental groups. Gradual reduction of immunosuppression did not result in an atraumatic replacement of donor derived Schwann cells by recipient derived ones. Allogenic nerve grafting needs continuous immunosuppression, which to date precludes it from clinical application.

[Timing of free microsurgical tissue transplantation in hand injuries during the acute phase]. / Zeitpunktwahl der freien mikrochirurgischen Gewebetransplantation bei Handverletzungen in der Akutphase.

Due to favourable survival rates in replantation surgery and a high standard of free tissue transplantation, the interval between injury and microsurgical reconstruction has continuously decreased in the past. The acute phase can be defined as the interval ranging from emergency procedures within 24 hours to "urgence différée" procedures within 72 hours. Bearing in mind the infection rates of 1.5% and 17.5% respectively as it has been reported in the literature, we should encourage emergency reconstructions. However, in most cases of upper extremity injuries, reconstruction with conventional flaps is possible. Between 1981 and 1991, 674 free tissue transplantation have been performed in our unit, 61% of the cases of free tissue transplantations to the upper extremity were done in the acute phase, the majority within 72 hours (urgence différée). No significant differences in rates of infections were evident comparing acute phase and urgence différée procedures. Because of this, we still support the concept of urgence différée. In our opinion the following advantages have to be considered: urgence différée allows a second loop operation, the vitality of the extremity can be ascertained, and the reconstructive procedure can be planned more precisely. Last not least, a procedure performed during the day-time assures better operating conditions. This concept is demonstrated with clinical cases.

Preservation of peripheral nerve grafts: a comparison of normal saline, HTK organ preservation solution, and DMEM Schwann cell culture medium.

The regeneration of peripheral nerve grafts was evaluated in a rat model, after pretreating the grafts with Schwann cell culture medium, HTK organ preservation solution, and normal saline, under cold ischemic conditions for different time periods. Following orthotopic replantation of the grafts into donor animals, the quality of regeneration was assessed after 6 weeks, compared to positive controls (autologous transplantation) and negative controls (acellular grafts). The regenerative quality in the Schwann cell culture groups with ischemic periods of 32 and 72 hr was comparable to normal controls. Significantly minor regeneration was detected in specimens undergoing 14 and 120 hr of ischemia in the Schwann cell culture medium and in the HTK and normal saline groups, regardless of ischemic time. Among the conclusions was that controlled proliferation of Schwann cells seems to be a basic principle for preservation of peripheral nerve grafts.

[Muscle-specific changes in free latissimus dorsi transplantation in the rat model]. / Muskelspezifische Veränderungen bei der freien Latissimus dorsi-Transplantation im Rattenmodell.

The aim of this study is to gain further knowledge concerning the regeneration of reinnervated, freely transplanted muscles. Therefore, we used a rat model, consisting of eight rats per group, in which the latissimus dorsi muscle was transplanted orthotopically, after a period of time of two and twelve weeks harvested, then evaluated histologically and enzyme-histochemically. As controls we used a group of non-operated muscles. At date of removal, the patency of the vascular anastomoses was checked clinically and histologically. Additionally, electrophysiological measurements and conventional and enzyme-histochemical histologies were performed. Two weeks after the free neurovascular flap transplantation, the muscle was not innervated yet, histologically a dissolved pattern of type 1 and type 2 muscle fibers was found. After twelve weeks of time, the muscles were reinnervated again, muscle contraction was positive after electrical stimulation and the typical pattern of fibers was reestablished.

Morphometric changes in free neurovascular latissimus dorsi flaps: an experimental study.

This study was designed to investigate regeneration of reinnervated, free transplanted muscles. We used a rat model, consisting of eight rats per group, in which the latissimus dorsi muscle was transplanted orthotopically and then harvested and evaluated after 2 and 12 weeks. Age-matched control animals were used to oppose non-operated muscles. At date of removal the patency of the vascular anastomoses was checked clinically and histologically. Electrophysiological measurements were also performed and conventional and enzyme histochemical histological slides manufactured. Two weeks after the free neurovascular flap transfer the muscle was not yet innervated, and histologically a dissolved pattern of type 1 and type IIA muscle fibres was found. The muscle fibres demonstrated a decrease of more than 50% cross-sectional area. After 12 weeks the muscles were reinnervated again; muscle contraction was positive with electrical stimulation and the cross-sectional area had regained 80% of the activity of normal muscle fibres. With enzyme histochemical staining the typical type grouping of reinnervated muscles could be demonstrated.

[Regeneration of peripheral nerves after interposition of acellular muscle into larger defects]. / Regeneration peripherer Nerven nach Interposition grösserer Defekte durch azellulären Muskel.

Peripheral nerve grafting is an established procedure in reconstructive surgery. Nerve grafts, however, are only available to a limited extent and patients are faced with neurologic deficits at the donor areas. Pretreated skeletal muscle has been proposed as an alternative grafting material. In nine adult Sprague-Dawley rats, a 2 cm gap of the sciatic nerve is grafted with a M. gracilis segment which has been pretreated through repeated freezing and thawing. Regeneration is evaluated after six weeks postoperatively. The results are compared to nine conventional nerve grafts. Regeneration was evident in all grafts. Histologically, the muscle grafts revealed a high proportion of connective tissue, a good vascularisation but an inferior degree of myelinisation. Morphometrically, the muscle grafts proved to be inferior according to axon counts and myelinisation. Muscle grafts provide a substrate comparable to peripheral nerves regarding the tubular architecture based on laminin. There are however no viable Schwann cells within these substitutes, which makes them inferior compared to conventional nerve grafts for peripheral nerve repair. These results are discussed with respect to further experiments concerning allogeneic nerve grafting and peripheral nerve preservation.

[The Dellon tube in injuries of peripheral nerves]. / Die Dellon-Röhrchen bei Verletzungen peripherer Nerven.

Experimental efforts are being undertaken to improve nerve transplantation as a method for peripheral nerve repair. Major disadvantages of nerve transplantation are the creation of neurologic deficits at the donor site and the limited availability of nerve grafts. Mackinnon and Dellon propose the interposition of synthetic, biodegradable tubes as a nerve conduit for clinical use. This method is described according to its theoretical background and the surgical technique. The interposition of synthetic tubes seems possible for short defects in finger nerves, but will render unfavourable results in long defects of peripheral mixed nerves.

Peripheral nerve allografts: survey of present state in an experimental model of the rat.

Rejection and regeneration processes in peripheral nerve allografts are analyzed in this review of a series of experiments with special reference to the possible clinical application of peripheral nerve allografting in clinical reconstructive surgery. A long segment of the sciatic nerve (2.5 cm) was grafted between congenic rat strains across a maximal genetic barrier; immunohistologically, donor- and recipient-derived structures can be differentiated. If allografting was performed without immunosuppression, a rejection response with consecutive regeneration of minor quality was observed. Under immunosuppression with cyclosporin A no rejection response was observed and regeneration quality was comparable to control autografts. The persistence of donor-derived Schwann cells in the immunosuppressed allografts can be demonstrated immunohistologically. After discontinuation of immunosuppression a rejection response is exerted. We conclude that Schwann cells are eliminated from peripheral nerves during rejection. Consecutive regeneration of minor quality is possible, which implies the ingrowth of recipient-derived Schwann cells into the rejected allograft. Under immunosuppression, allogenic Schwann cells survive and actively promote regeneration. They are still immunologically competent and can exert rejection when immunosuppression is discontinued. A certain degree of replacement of donor-derived Schwann cells seems possible.