Quantitative evaluation of blood perfusion to nerves included in the anterolateral thigh flap using indocyanine green fluorescence angiography: a different contrast pattern between the vastus lateralis motor nerve and femoral cutaneous nerve.

BACKGROUND: Better postoperative results can be expected in nerve reconstruction when vascularized nerve grafts are used. Previous studies reported reconstruction with flaps including "vascularized" nerves; however, few have evaluated blood supply to these nerves. The aim of this study was to quantitatively assess blood perfusion to nerves included in anterolateral thigh (ALT) flaps by indocyanine green (ICG) fluorescence angiography. PATIENTS AND METHODS: Participants comprised eight patients who underwent reconstructive surgery with nerve defects using free ALT flaps, including the vastus lateralis motor nerve and/or femoral cutaneous nerve. Intraoperative ICG fluorescent angiography was performed. Time after the drug injection and the intensity of fluorescence in these nerves were analyzed as time-intensity curves. Maximum intensity (Imax), time to Imax (Tmax), and time at the beginning of intensity elevation (Te) were measured at three points: Point C, the central portion of the flap-attached region of the nerve; Point P, 2 cm from the proximal flap-attached edge; and Point D, 2 cm from the distal edge. RESULTS: Imax and Te at point C and Imax/Tmax-Te at point P were significantly different between these two nerves (p = 0.03125, p = 0.02895, p = 0.03125, respectively). Fluorescence in the vastus lateralis motor nerve was slightly quicker and stronger than that in the femoral cutaneous nerve, and also exhibited an axial pattern of fluorescence. CONCLUSION: Intraoperative ICG fluorescent angiography can be used to determine which nerve is better for nerve reconstruction. The indexes of Imax, Te, and Imax/Tmax-Te may be the suitable criteria for decision making regarding donor nerve selection.

Ischemia of the lateral femoral cutaneous nerve during periacetabular osteotomy using Smith-Petersen approach.

BACKGROUND: Lateral femoral cutaneous nerve (LFCN) injury is a common complication in the Smith-Petersen approach to the hip. This complication may be induced by neural ischemia or direct trauma during the procedure. The purpose of this study was to investigate the relationship between the neural ischemia of LFCN and postoperative sensory disturbance. MATERIALS AND METHODS: Nineteen patients who underwent periacetabular osteotomy through the Smith-Petersen approach were investigated. To evaluate neural ischemia, we measured the blood flow of LFCN using a laser Doppler flowmetry. The measurements were performed before and after osteotomy at the point 1 cm distal from the lower border of the inguinal ligament. LFCN was retracted to the medial side during the procedure. There was no direct trauma to LFCN in all cases. Postoperative sensory disturbance was evaluated at 2 weeks, 3 months, and 1 year follow-up after surgery. RESULTS: After osteotomy, the blood flow of LFCN was decreased to 2.4 from 3.3 ml min(-1) 100 g(-1) when compared with that before osteotomy (P < 0.01). Postoperatively, 14 of 19 patients had sensory disturbance at 2 weeks, 8 of 19 patients at 3 months, and 2 of 19 patients at 1 year follow-up. The blood flows of both patients who had persistent symptoms over 1 year after surgery had been decreased by more than 50% during operation. CONCLUSIONS: Decrease of blood flow of LFCN by more than 50% seems to cause persistent symptoms after surgery through the Smith-Petersen approach even if direct trauma to the nerve is avoided. Excessive traction by retractors is thought to be the main cause of blood flow reduction.

Neurovascular anatomy of sartorius muscle flaps: implications for local transposition and facial reanimation.

BACKGROUND: The sartorius muscle is a superficial muscle of the thigh that possesses highly suitable qualities for many uses in local transposition and free muscle transfer. However, a paucity of description of the neurovascular anatomy of the sartorius has contributed to its infrequent use in these roles. METHODS: Both human and canine studies were undertaken to delineate the neurovascular anatomy of the sartorius and to determine the role for surgical delay clinically. Fifty-five human cadaveric sartorius muscles and 30 canine cadaveric sartorius muscles underwent angiographic and dissection studies, and the location and course of the vessels and nerves supplying sartorius are described. A subsequent study was undertaken in two live canines in which the vascular supply to the sartorius was evaluated before and after surgical delay. RESULTS: The sartorius is supplied by an average of six or seven vascular pedicles, the size, location, and course of which are described. The nerve supply to the sartorius enters at its proximal end and uniformly arises from a branch of the femoral nerve. Variations in branching patterns and course of nerves and vessels are described. Living canine studies demonstrated the dilatation of intramuscular vessels following surgical delay, with the contrast injection of a single remaining vascular pedicle shown to vascularize the entire length of the sartorius muscle. CONCLUSIONS: The sartorius is highly suitable for local transposition and free muscle transfer for facial reanimation. The neurovascular anatomy is reliable, and the use of surgical delay can augment its vascular supply and increase the arc of rotation for local transposition.

Impact of vascularization type on peripheral nerve microstructure.

Experimental and clinical studies have demonstrated that vascularized nerve grafts are superior to nonvascularized nerve grafts with respect to healing. By means of the inherent vascularity in vascularized nerve grafts, Schwann cells remain viable, and endoneurial necrosis and fibrosis are not seen. In this study the effects of three different vascularization patterns on the vascular microstructure of a nerve segment in the rat based on the femoral artery and vein was investigated. Sixty adult male Wistar Albino rats were divided into five groups. In each group, a 1.5-cm segment of femoral nerve was transected at two sides, without disturbing the unity of the contents of the femoral sheath. The experimental design consisted of prefabricated venous nerve segment, venous nerve segment, arterial nerve segment, no blood flow, and controls groups. To assess the microstructure of the nerve segment, myelin and Schwann cell morphology and fibrosis were examined. There were many Schwann cells with near normal morphology in the venous nerve segment and arterial nerve segment groups. In conclusion, the venous nerve segment model in which Schwann cell viability was high due to the presence of sufficient and uninterrupted blood supply to the nerve graft, resulting in successful nerve healing, showed superior results over others.

A modification of the neural-island flap: 'split neural-island flap'.

The purpose of this study was to demonstrate the new concept of a consistent and reliable skin-flap design supplied solely by the intrinsic vasculature of a split cutaneous nerve. A total of 88 Wistar rats were used in this experiment, which was divided into three parts. In Part I (n=20), the vascular anatomy and the fascicular anatomy of the lateral femoral cutaneous nerve were established. In Part II (n=44), split neural-island flaps were created. Two skin flaps (measuring 2x3 cm each) were harvested based solely on the lateral femoral cutaneous nerve, which was split into two based on its fascicles. In Part III (n=24), a surgical delay procedure was applied in order to augment the survival areas of split neural-island flaps. On postoperative day 7, the viability of all flaps was evaluated. The results of the anatomic studies demonstrated that the lateral femoral cutaneous nerve consisted of usually two (80%), rarely three, fascicles (20%). Meticulous dissection enabled us to separate these fascicles without disrupting the perineural vasculature around each fascicle. The mean flap survival rate in the acutely elevated split neural-island flap group in Part II was 6.2+/-3.1%, whereas survival in the graft group was 0.0%. Results of Part III of the experiment demonstrated a significantly higher survival rate for the delayed split neural-island flap (98.5+/-2.8%) compared to the acutely elevated split neural-island flap (P<0.05). In conclusion, this is a reliable skin flap that can be nourished solely by the intrinsic vasculature of an interfascicularly dissected ('split') nerve.

Neuroregeneration in composite tissue allografts: effect of low-dose FK506 and mycophenolate mofetil immunotherapy.

BACKGROUND: The immunosuppressant FK506 has been reported to increase the rate of peripheral nerve regeneration in nerve crush injury and nerve allograft models. The purpose of this study was to determine whether low doses of FK506 and mycophenolate mofetil had a neuroregenerative effect in revascularized peripheral nerve allografts in a rat hind limb transplantation model. METHODS: Wistar Furth rat recipients received limbs from syngeneic Wistar Furth donors (group 1, n = 4) or from allogeneic August X Copenhagen Irish rat donors (group 2, n = 6). Wistar Furth recipients received limbs from August X Copenhagen Irish donors and were treated with FK506/mycophenolate mofetil for 5 months (group 3, n = 7). At the end of the follow-up period, histomorphometric analysis of sciatic and tibial nerves from transplanted and intact hind limbs was conducted. Sciatic and tibial nerves were examined at the level of coaptation and near the neuromuscular junction, respectively. RESULTS: Transplanted limbs in groups 1 and 3 completed the study without rejection, while the limbs in group 2 were rejected within a few days. Sciatic and tibial nerve analysis in groups 1 and 3 limbs showed myelinated axons of various diameters but in significantly fewer numbers than in nontransplanted contralateral nerves. The number and size of myelinated axons of transplanted nerves at corresponding levels were not significantly different between syngeneic and allogeneic (FK506/mycophenolate mofetil-treated) transplants. CONCLUSIONS: The authors conclude that long-term neuroregeneration of revascularized peripheral nerves using low-dose FK506/mycophenolate mofetil was similar to that of syngeneic transplants. The occurrence of acute rejection episodes with low-dose FK506/mycophenolate mofetil did not appear to benefit nor impair neuroregeneration.

Changes in nerve root motion and intraradicular blood flow during intraoperative femoral nerve stretch test. Report of four cases.

OBJECT: It is not known whether changes in intraradicular blood flow (IRBF) occur during the femoral nerve stretch test (FNST) in patients with lumbar disc herniation. An FNST was conducted in patients with lumbar disc herniation to observe the changes in IRBF, and results were then compared with clinical features. METHODS: The study was composed of four patients with L3-4 disc herniation who underwent microdiscectomy. Patients were placed prone immediately before surgery, so that their knee flexed on the operating table with the hip joint kept in hyperextension, and the FNST was performed to confirm at which region pain developed in the anterolateral thigh. During the operation, the hernia-affected nerve roots were visualized under a microscope. The needle sensor of a laser Doppler flowmeter was then inserted into each nerve root immediately above the hernia, and the change in IRBF was measured during the intraoperative FNST. After removal of the herniated disc, a similar procedure was repeated and IRBF was measured again. The intraoperative FNST showed that the hernia compressed the nerve roots and there was marked disturbance of gliding, which was reduced to only a few millimeters. During the test, IRBF decreased by 92.8 to 100% (mean 96.9 +/- 3.7% [+/- standard error of the mean]) relative to the blood flow before the test. This study demonstrated that the blood flow in the nerve root is reduced when the nerve root is compressed in vivo. CONCLUSIONS: The intraoperative FNST showed that the hernia compressd the nerve roots and there was marked disturbance of gliding, which was reduced to only a few millimeters. During the test, IRBF decreased by 92.8 to 100% (96.9 +/- 3.7% [mean +/- standard error of the mean]).

Nerve biopsy findings in different patterns of proximal diabetic neuropathy.

Besides distal symmetrical sensory polyneuropathy (DSSP), middle-aged diabetic patients may present with focal or multifocal neuropathies, including proximal neuropathy of the lower limbs, the pathophysiological features of which are uncertain. We studied 10 non-insulin-dependent diabetic patients, 45 to 72 years of age, who developed a painful proximal neuropathy of the lower limbs for which other causes of neuropathy were carefully excluded. The proximal neuropathy was asymmetrical in all patients, sensory in 4, motor and sensory in the others. Signs of DSSP were present in all. A sample of the intermediate cutaneous nerve of the thigh, a sensory branch of the femoral nerve, was taken by biopsy and examined by light and electron microscopy. Examination of the nerve specimens revealed ischemic nerve lesions in 3 patients. Nerve ischemia was associated with vasculitis and inflammatory infiltration in 2 of them. In the other patients the lesions of the cutaneous nerve of the thigh included a varying incidence of axonal and demyelinative lesions similar to those observed in DSSP, with mild inflammatory infiltration in 4 of them. The density of myelinated and of unmyelinated was variably decreased. This study shows that axonal and demyelinative lesions similar to those found in diabetic DSSP are present in proximal nerves in mild forms of proximal diabetic neuropathy; while nerve ischemia, inflammatory infiltration, and vasculitis are encountered in the most severe forms of proximal diabetic neuropathy.

[Neurogenic intermittent claudication of the femoral nerve caused by occlusion of the common iliac artery]. / Neurogene Claudicatio intermittens des N. femoralis durch Verschluss der A. iliaca communis.

A 52 year old heavy smoker complained of paresthesiae and pain at the ventral side of the right thigh and the antero-medial side of the right lower leg as well as weakness of the right quadriceps femoris during exercise. Clinical examination revealed a paresis of the right quadriceps, hypesthesia and hypalgesia in the area of the femoral nerve and a reduced right patellar reflex after 10 min walking. An occlusion of the right common iliac artery was diagnosed by angiography. Following transluminal angioplasty and implantation of an intravascular stent, the patient was free of symptoms. On the basis of the clinical observations following recanalisation of the common iliac artery, the symptoms can best be explained by a reduced perfusion of the iliolumbar artery supplying the upper part of the femoral nerve, causing ischemia of the femoral nerve during exercise. In conclusion, stenosis/occlusion of the common iliac artery should be considered as a differential diagnosis of quadriceps weakness and paresthesia in the area of the femoral nerve associated with exercise.

A substantial part of GLUT-1 in crude membranes from muscle originates from perineurial sheaths.

The distribution of GLUT-1 and GLUT-4 in cryosections of rat skeletal muscles was investigated immunocytochemically. Intense labeling of GLUT-1 was found in the perineurial sheaths of intramuscular nerves, whereas only a very faint signal was associated with the sarcolemma, and labeling of extraneural vessels was not detectable. The majority of the GLUT-4 reactivity was located at the periphery of muscle cells in nonuniform patches, and GLUT-4 was absent in vessels and nerves. In sections of femoral nerve GLUT-1 was confined to the perineurial sheath and endoneurial vessels. The contribution of GLUT-1 from intramuscular perineurial sheaths to total GLUT-1 in a muscle was determined from immunoblots of crude membranes isolated from mixtures of homogenates of excised nerves and muscles. The recovery of GLUT-1 increased linearly with the amount of nerve added, and it was calculated that GLUT-1 from intramuscular perineurial sheaths accounted for approximately 60% of the GLUT-1 content in a membrane fraction from soleus muscle or red gastrocnemius. The remaining 40% of GLUT-1 is likely to originate from the sarcolemma.

Study of microcirculation of rat femoral nerve and development of a new vascularized nerve graft model.

This study was designed to investigate the microcirculation of the rat femoral nerve and to develop a vascularized nerve graft (VNG) model which is reliable, consistent, and simple. The rat was chosen for considerations of cost and simplicity of the model. One and 2 cm long femoral nerve segments were transected proximally and distally and left attached to the femoral artery and vein in all animals. Experimental groups included the following procedures: 1) the femoral artery and vein were ligated distally and an arteriovenous (AV) fistula just proximal to the ligature was constructed; 2) distal ligation only of the femoral artery and vein was done; 3) ligation of the femoral artery and vein was done both distally and proximally; 4) control: no ligation or construction of an AV fistula were done. Neurovascular segments in all groups were wrapped with a thin silicone sheath to prevent neurovascularization from the surrounding tissues. At seven days postoperatively, viability of the segments was assessed by fluorescein dye and microangiography studies, followed by histologic evaluation. Results showed that a 1- or 2-cm long femoral nerve segment, when left attached to distally ligated femoral vessels and an intact neurovascular sheath, is a simple design to reproduce and can serve reliably as a VNG model in the rat.

Femoral neuropathy as a complication of aortic surgery.

In a series of 1006 aortic operations for atherosclerotic occlusive or aneurysmal disease a femoral neuropathy with paresis of the quadriceps femoris muscle and sensory disturbances occurred in 34 patients or 3.4%. The femoral nerve palsy was left-sided 23 times, right-sided 9 times and bilateral twice. Twenty-nine patients had a complete recovery after 1/2 to 1 years. It is suggested that the femoral neuropathy is of ischaemic nature and caused by aortic clamping. The scant blood supply of the intrapelvic section of the femoral nerve is derived from the iliolumbar artery, a branch of the internal iliac artery, and from the deep circumflex iliac artery, a branch of the external iliac artery. On the right side the deep circumflex iliac artery gives more branches to the nerve and there are more anastomoses with the fourth and fifth lumbar arteries, than on the left side. This may be the explanation for the preference of the nerve palsy for the left side.

Regeneration in vascularized and free nerve grafts. A comparative morphological study in rats.

The regeneration of vascularized nerve grafts was compared with conventional free "cable" grafts. For the creation of a vascularized femoral nerve graft in the rat an arteriovenous fistula was constructed to overcome blood flow problems. The histo-morphological results showed better and more rapid regeneration in the group with a vascular pedicle. The arteriovenous fistulae were all patent even after five months.

Histological studies of vascularised nerve graft and conventional nerve graft.

Histological studies of vascularised nerve graft versus conventional nerve graft were performed in eighteen rat femoral nerves using microsurgical technique. This experiment showed that there was no difference in the degree of vascularisation, reticulin framework collapse, rate and extent of axonal regeneration and remyelination between the two groups.

Femoral neuropathy due to common iliac artery occlusion.

A patient with an atherosclerotic common iliac artery occlusion had acute onset of femoral neuropathy, which resolved after revascularization. This case indicates that ischemia can cause femoral neuropathy and that ischemia may be the explanation for some previously unexplained postoperative femoral neuropathies.

Subclinical entrapment of the lateral femoral cutaneous nerve: an autopsy study.

Five out of 12 lateral femoral cutaneous nerves, removed at routine autopsies, showed pathologic changes in myelinated nerve fibers in the vicinity of the inguinal ligament. These changes included both local demyelination and Wallerian degeneration, particularly affecting the fibers with the largest diameters. The presence of polarized internodal swellings on single nerve fibers from two specimens suggested that mechanical factors were involved in pathogenesis. Endoneurial vascular thickening confined to the region of the inguinal ligament was also seen and may be implicated in the production of some of the symptoms of meralgia paresthetica (MP).