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Prevention and management of sigmoid and pelvic ischemia associated with aortic surgery.

Ischemia of the colon, rectum, and pelvis continues to be a significant source of morbidity and mortality after aortic reconstruction. Complications associated with colonic and pelvic ischemia are severe and include impotency, buttock claudication, colonic and rectal infarction, buttock and perineal necrosis, and spinal cord or lumbar plexus injury. To prevent these complications the vascular surgeon must make every attempt to guarantee the adequacy of colonic and pelvic blood supply after aortic reconstructive procedures. During open surgical repair of aneurysms or aortoiliac arterial occlusive disease, patent inferior mesenteric arteries must either be routinely reimplanted or selectively ligated on the basis of object intraoperative assessment of colonic perfusion. In addition, when possible, antegrade perfusion should be maintained in patent internal iliac arteries, and femoral reconstructions should include reconstruction of the deep femoral artery to assure adequate perfusion of potential pelvic collaterals. The rate of colonic and pelvic ischemia after endovascular aneurysm repair appears lower than after open repair, but all of the complications of colonic and pelvic ischemic seen after open repairs have been reported after endoluminal aneurysm repair. Thus, during stent-graft repair of abdominal aortic aneurysms, all attempts also should be made to preserve pelvic perfusion by maintaining antegrade flow to a least one patent internal iliac artery. The principle to remember in the management of complications of pelvic ischemia associated with aortic reconstruction is prevention because when complications of pelvic ischemia occur, the damage often is irreversible.

Aorta↗

Ropivacaine plasma concentrations are similar during continuous lumbar plexus blockade using the anterior three-in-one and the posterior psoas compartment techniques.

PURPOSE: To compare ropivacaine blood concentrations obtained after a continuous lumbar plexus block performed either by the anterior three-in-one femoral (FEM) technique or the posterior (psoas compartment; PSOAS) technique. METHODS: As a substudy of a larger clinical trial, 24 patients were randomly allocated to receive a bolus of 30 mL of ropivacaine 0.5% plus epinephrine 1:200,000 followed by an infusion of ropivacaine 0.2% at 12 mL.hr(-1) for 48 hr via one of the two continuous lumbar plexus block techniques. Plasma ropivacaine concentrations, up to 48 hr, were measured by high performance liquid chromatography. RESULTS: Mean plasma ropivacaine concentrations were higher in the PSOAS group at 15, 30, and 60 min (two-way analysis of variance, P < 0.0001) but areas under the curve were similar for both groups (FEM 452.4 +/- 253.6 mg.hr(-1).L(-1), PSOAS 433.4 +/- 99.0 mg.hr(-1).L(-1)). Mean maximal plasma concentrations were observed at 48 hr and were comparable for the two techniques (FEM 2630.9 +/- 1470.3 ng.L(-1), PSOAS 2325.1 +/- 604.2 ng.mL(-1)). There was no correlation between blood concentrations at 48 hr and body weight (r2 = 0.085, P = 0.21). One patient in the FEM group achieved a concentration of 6201 ng.mL(-1) at 48 hr. CONCLUSIONS: Although the posterior PSOAS block results in higher early plasma concentrations of local anesthetic than the anterior three-in-one FEM block, both techniques are equivalent with regards to their potential toxicity when a continuous infusion is administered. Local anesthetic accumulation occurs with an infusion of ropivacaine 0.2% at 12 mL.hr(-1) and can lead to potentially dangerous concentrations at 48 hr.

Adult↗

A description of the spread of injectate after psoas compartment block using magnetic resonance imaging.

BACKGROUND AND OBJECTIVES: Magnetic resonance imaging (MRI) provides for excellent visualization of spread of solution after peripheral nerve block. The aim of this observational study was to utilize MRI to describe the distribution of injectate (gadopentetate dimeglumine) administered for continuous psoas compartment block (PCB) performed by use of two approaches (Capdevila and modified Winnie) and to describe the spread of injectate to the lumbar plexus. METHODS: Four volunteers were enrolled in a prospective crossover study. Each volunteer underwent PCB with catheter placement performed by use of Capdevila's approach followed 1 week later by PCB, with catheter placement performed by use of a modified Winnie approach. MRI of injectate distribution was performed after each PCB. RESULTS: The catheter was unable to be inserted in 1 volunteer undergoing Winnie's approach; therefore, 7 sets of MR images were analyzed. In 6 of 7 cases (4 Capdevila and 2 Winnie) spread was primarily within the psoas muscle. Contrast surrounded the L2-3 lumbar branch of the femoral nerve at L4 and cleaved the fascial plane within the psoas muscle and spread cephalad to reach the lumbar nerve roots. In 1 case (Winnie approach) contrast spread between the psoas and quadratus lumborum muscles. Contrast surrounded the femoral and obturator nerves where they lie outside the psoas muscle at L5. CONCLUSION: The most common pattern of injectate spread seen on MRI with both approaches to PCB was spread within the body of the psoas muscle around the lumbar branches (L2-4), with cephalad spread to the lumbar nerve roots. One catheter resulted in injectate between the psoas and quadratus lumborum muscles.

Adult↗

Neuroanatomy of penile erection: its relevance to iatrogenic impotence.

The neuroanatomy of erection in men is not well defined. Recently, we isolated successfully the cavernous nerves for acute and chronic neurostimulation to induce penile erection in dogs and monkeys. We then investigated the anatomy of these nerves in humans by cadaveric dissection and serial histologic sectioning. Our experience in tracing the spinal nuclei responsible for vesical and urethral function by transportation of horseradish peroxidase enabled us to explore the location and organization of the spinal center for erection. Thus, systemic knowledge of the neuroanatomy of erection was accumulated. The spinal nuclei for control of erection are located in the intermediolateral gray matter at the S1 to S3 and T12 to L3 levels in dogs, and the S2 to S4 and T10 to L2 levels in humans. From these sacral nuclei axons issue ventrally and join the axons of the nuclei for the bladder and rectum to form the sacral visceral efferent fibers. These fibers emerge from the anterior root of S2 to S4, and join the sympathetic fibers to form the pelvic plexus, which then branches out to innervate the bladder, rectum and penis. The fibers innervating the penis (cavernous nerves) travel along the posterolateral aspect of the seminal vesicle and prostate, and then accompany the membranous urethra through the genitourinary diaphragm. These fibers are located on the lateral aspect of the membranous urethra and ascend gradually to the 1 and 11 o'clock positions in the proximal bulbous urethra. Some of the fibers penetrate the tunica albuginea of the corpus spongiosum, while others spread to the trifurcation of the terminal internal pudendal artery and innervate the dorsal, deep and urethral arteries. Shortly before the 2 corpora cavernosa merge the cavernous nerves penetrate the tunica albuginea along with the deep artery and cavernous vein. The terminal branches of these nerves innervate the helicine arteries and the erectile tissue within the corpora cavernosa. Because of the intimate relationship of the cavernous nerves to the rectum, prostate and urethra, they can be damaged easily during urological and pelvic procedures. This systemic knowledge of the human cavernous nerves from the spinal center to the erectile tissue should permit a better understanding of erection and impotence. Furthermore, with the aid of intraoperative neurostimulation, the cavernous nerves may be identified and preserved, thereby preventing iatrogenic impotence.

Animals↗

Adductor T and H reflexes in humans.

In the belief that changes in the adductor reflex (AR) may be helpful in evaluating lumbar root and plexus lesions, expression of the AR was studied in 43 healthy human subjects. ARs elicited with an electronic reflex hammer were recorded from the inner side of the proximal thigh using needle and surface electrodes, and patellar reflexes (PRs) were recorded simultaneously. These reflexes were obtained by tapping the ipsilateral medial aspect of the knee, the contralateral patellar tendon, the ipsilateral and contralateral anterior superior iliac spines, and the Achilles tendon. The H reflex of the obturator nerve was also evaluated in 17 cases. ARs were evoked consistently by tapping the ipsilateral medial aspect of the knee and by contralateral patellar tap, and by tapping ipsilateral and contralateral anterior superior iliac spines when a needle recording electrode was used. Sometimes an Achilles tendon tap also elicited the AR ipsilaterally. By contrast, the PR could only be elicited by a tap to the ipsilateral patellar tendon. ARs have somewhat different features than other well-known tendon reflexes such as the PR and are recorded consistently when a needle electrode is used, being elicited from both distal and proximal areas of the legs by tapping the Achilles tendon or anterior superior iliac spines unilaterally or bilaterally. Their role in evaluating lumbar root disease and monitoring adductor spasticity merits investigation.

Achilles Tendon↗

Sensory stimulation-guided sacroiliac joint radiofrequency neurotomy: technique based on neuroanatomy of the dorsal sacral plexus.

STUDY DESIGN: A retrospective audit and examination of anatomic findings. OBJECTIVE: To examine the effectiveness of sensory stimulation-guided radiofrequency neurotomy for the treatment of recalcitrant sacroiliac joint pain. SUMMARY OF BACKGROUND DATA: Sacroiliac joint-mediated pain is a distinct clinical entity. The prevalence of intra-articular pain arising from the sacroiliac joint in patients with low back pain has been estimated at 15% to 30%. Unfortunately, the clinical success of current treatment methods for chronic sacroiliac pain is discouraging. Based on the anatomy of the sacral posterior primary rami and their lateral branch nerves, an anatomically based sensory stimulation-guided radiofrequency technique was developed to overcome the inherent challenge posed by the variable topography of the sacral lateral branch nerves. MATERIALS AND METHODS ANATOMIC STUDY: Meticulous dissection exposing the dorsal sacral plexus and lateral branch nerves entering the sacroiliac joint complex was performed on three cadaveric specimens. Small-gauge wires were placed adjacent to the lateral branch nerves entering the joint and over the dorsal sacrum to the dorsal sacral foramina. Fluoroscopic images were obtained correlating the location and number of these branches arising from the posterior primary rami of S1-S3 to identifiable bony landmarks. CLINICAL STUDY: A retrospective chart review was performed selecting patients who underwent sensory stimulation-guided sacral lateral branch radiofrequency neurotomy after dual analgesic sacroiliac joint deep interosseous ligament analgesic testing between February 17, 1998 and March 15, 1999. RESULTS: A total of 14 patients met inclusion criteria for this retrospective study. Success was defined as greater than 60% consistent subjective relief and greater than a 50% consistent decrease in visual integer pain score, maintained for at least 6 months after the procedure. Sixty-four percent of patients experienced a successful outcome, with 36% experiencing complete relief. Fourteen percent of patients did not achieve any improvement. No patients experienced a complication or worsening of their pain from the procedure. CONCLUSIONS: A sensory stimulation-guided approach toward the identification and subsequent radiofrequency thermocoagulation of symptomatic sacral lateral branch nerves appears to offer significant therapeutic advantages over existing therapies for the treatment of chronic sacroiliac joint complex pain.

Adult↗

The posterior lumbar plexus (psoas compartment) block and the three-in-one femoral nerve block provide similar postoperative analgesia after total knee replacement.

PURPOSE: To compare the efficacy of a continuous posterior lumbar plexus (PSOAS) block to a continuous three-in-one femoral nerve (FEM) block in patients undergoing primary total knee replacement (TKR). METHODS: Sixty patients were randomly allocated to receive iv patient-controlled morphine analgesia (PCA), PCA plus a continuous FEM block with 30 mL ropivacaine 0.5% and epinephrine 1:200,000 bolus followed by an infusion of ropivacaine 0.2% at 12 mL.hr(-1) for 48 hr, or PCA plus a continuous PSOAS block with the same bolus and infusion regimen as the FEM group. Postoperative morphine consumption, verbal analogue scale pain scores at rest and during physiotherapy, and evidence of sensory and motor blockades were noted. RESULTS: Both regional techniques significantly reduced 48 hr morphine consumption (FEM 37.3 +/- 34.7 mg, P = 0.0002; PSOAS 36.1 +/- 25.8 mg, P < 0.0001) compared to PCA (72.2 +/- 26.6 mg). Pain scores at rest, six and 24 hr after TKR were lower in the FEM and PSOAS groups compared to the PCA group (P < 0.0001). Although sensory and motor blockades of the obturator nerve were achieved more often in the PSOAS group than in the FEM group (P < 0.0001), morphine consumption and pain scores did not differ between the two groups. CONCLUSION: Both continuous PSOAS block and continuous three-in-one FEM block provided better analgesia than PCA but no differences were seen between the two regional techniques.

Adult↗

Use of sequential electrical nerve stimuli (SENS) for location of the sciatic nerve and lumbar plexus.

BACKGROUND AND OBJECTIVES: Conventional electrical stimulation has been done by continuous adjustment of current amplitude at a single, set pulse duration (conventionally, 0.1 ms). This study evaluated a novel technique for nerve location by utilization of a peripheral-nerve stimulator (PNS) programmed to deliver sequential electrical nerve stimuli (SENS). A repeating series of alternating sequential pulses of 0.1, 0.3, and 1.0 ms at 1/3-second period intervals between pulses were generated so that at a greater distance from the nerve, only higher-duration pulses would stimulate the targeted nerve and result in 1 or 2 motor responses (MR) per second. Three MR per second at 0.5 mA or less signified the conventional endpoint for nerve location (</=0.5 mA, 0.1 ms) because that value indicated that the 0.1-ms pulse was effective. The conventional 0.1-ms pulse served as a built-in control to which the SENS was compared. METHODS: Sixteen sciatic/psoas blocks were performed on 8 patients. Nerve location was by SENS, with an 80-mm block needle. Needle advance began at 1.0 mA until MR. If 1 or 2 MR/s occurred, the needle was advanced until 3 MR/s were obtained. When 3 MR/s occurred at 0.5 mA or less, needle position was fixed (final position), and mA further decreased until MR disappeared. Two digital video cameras separately recorded needle depth and MR for analysis. Final needle position was designated as zero, and distance was calculated relative to it. RESULTS: In 12 of 16 of the performed blocks, SENS resulted in advanced notification (1 or 2 MR/s), which yielded additional visual feedback compared with control before final nerve location and, thus, increased range. In 15 of 16 blocks, MR did not disappear, once elicited, through final needle location. CONCLUSIONS: SENS resulted in increased sensitivity without compromising specificity of nerve location.

Adult↗

Multiple lumbar plexus neurotizations of the ninth, tenth, and eleventh intercostal nerves.

The topographic anatomy of the lower intercostal nerves is less known than the upper ones except for the twelfth intercostal nerve. It is possible to use the lower intercostal nerves to carry out a neurotization of the lumbar roots. We studied the anatomy of the ninth, tenth, and eleventh intercostal nerves in order to specify the data of descriptive and topographic anatomy allowing to carry out their harvesting under good conditions. Ninth, tenth, and eleventh intercostal nerves of 50 cadavers were dissected. The proximal part of the nerve in the posterior intercostal space was exposed through a posterior approach. The lateral intercostal space was exposed through a lateral approach, under the latissimus dorsi, which made it possible to harvest the intercostals nerve. The proximal course of the nerve in posterior intercostals space was the same in all the cases. The nerve moves obliquely towards the outside to reach the lower border of the rib. The exit of posterior intercostal space is a fibrous strait that marks the entry of a channel between two muscular layers. We describe an aponevrotic channel in which the nerve and the vessels are, immediately at the lower border of the cranial rib. The mean total length of intercostal nerve harvested by our technique was 17.96 cm for the ninth intercostal nerve, 17.14 cm for the tenth intercostal nerve, and 15.94 cm for the eleventh intercostal nerve. The bifurcation of the intercostal nerve in a deep branch and the ramus cutaneus lateralis was found in the majority of the cases, from 9.5 to 21 cm of the emergence of the intercostal nerve in posterior intercostal space. This anatomical study of the ninth, tenth, and eleventh intercostal nerves in posterior intercostal space and lateral intercostal space appears to us to allow the realization of a reliable surgical harvesting.

Cadaver↗

Postoperative analgesia and functional recovery after total-knee replacement: comparison of a continuous posterior lumbar plexus (psoas compartment) block, a continuous femoral nerve block, and the combination of a continuous femoral and sciatic nerve block.

BACKGROUND AND OBJECTIVES: Continuous femoral nerve block is a well-accepted technique for regional analgesia after total-knee replacement. However, many patients still experience considerable pain at the popliteal space and at the medial aspect of the knee. The goal of this study is to evaluate whether a psoas compartment catheter provides better postoperative analgesia than a femoral nerve catheter does and whether it is as effective as the combination of a femoral and a sciatic nerve catheter and, thus, improves functional outcome. METHODS: Ninety patients who underwent total-knee replacement under standardized general anesthesia participated in this prospective randomized study. Group FEM received a continuous femoral nerve block, group FEM/SCI received a combination of a femoral and a sciatic continuous nerve block, and group PSOAS received a continuous psoas compartment block. Patient-controlled analgesia with piritramide was available for 48 hours. Maximal bending and extending of the knee and walking distance was assessed during the first 7 days. A standardized telephone survey was conducted after 9 to 12 months to evaluate residual pain and functional outcome. RESULTS: Postoperative opioid consumption during 48 hours was significantly less in the FEM/SCI group (median: 18 mg; 25th/75th percentile: 6/40) compared with the FEM group (49 mg; 25/66) and the PSOAS group (44 mg; 30/62) (P =.002). Postoperative pain scores were not different, and no differences occurred with respect to short-term or long-term functional outcome. CONCLUSION: The FEM/SCI catheter is superior to FEM and PSOAS catheter with respect to reduced analgesic requirements after total-knee replacement, but functional outcome does not differ with those 3 continuous regional analgesia techniques.

Aged↗

Control of canine membranous urethra, bulbocavernosus and ischiocavernosus muscles by lumbosacral sympathetic pathways.

The membranous urethral muscles, bulbocavernosus muscle (BCM) and ischiocavernosus muscle (ICM) play a significant role on expulsion at ejaculation. Projection of the sympathetic pathways in the retroperitoneum to these muscles was investigated in the dog. Intraluminar pressure of the membranous urethra and contractions of the BCM and ICM to electrical stimulation of the lumbar splanchnic nerve (LSN) or the lumbosacral sympathetic chain (LSC) were examined. Stimulation of the LSN was performed after transection of the unilateral hypogastric nerve (HGN) to clarify its cross-innervation. Stimulation of each of the 2nd to 4th LSNs elicited elevation of the intraluminal pressure of the membranous urethra. In eight dogs whose right HGNs were transected, 15 of the 19 right LSNs, and 12 of the 16 left LSNs examined elicited elevation of the membranous urethral pressure, respectively. In five dogs whose left HGNs were transected, 6 of the 9 right LSNs and 10 of the 12 left LSNs stimulated elicited elevation of the pressure. Stimulation of the HGN caused no detectable contractions of the BCM and ICM in all six dogs examined. Stimulation of the LSC elicited responses of the BCM and ICM in all six dogs examined and the membranous urethra in three of six dogs. The maximum value of the response of the BCM was greater than that of the ICM. After consecutive transection of the ipsilateral pelvic nerve, stimulation of the LSC showed no significant changes in the responses of the BCM and ICM. The above results indicate the following: (1). each of the L2-L4 LSNs sends signals to the membranous urethra via two routes, passing through the ipsilateral or contralateral HGN; (2). the above nerve does not send effective signals to the BCM and ICM; (3). the LSC sends signals to the membranous urethra, BCM and ICM; (4). the signals from the LSC mainly pass through the pudendal nerve to the BCM and ICM; and (5). the signals were dominant to the BCM compared with the ICM.

Animals↗

On the organization of the Plexus lumbalis. I. On the recognition of the three-layered divisions and the systematic description of the branches of the human femoral nerve.

The arrangement of the nerve bundles at the branching point of the femoral nerve (F), the interrelations of the branches each other and toward other nerves in the anterior region of the thigh, and the patterns and the anatomical features of both the running courses and the distributions of the branches were macroscopically studied, whereby some special findings were observed and the following results were obtained: 1) The periphery of the femoral nerve was fundamentally divided into superficial-deeply arranged three-layered divisions. Including the femoral branch of the genitofemoral nerve (Rf) and the femoral lateral cutaneous nerve (Cfl), the nerve branches at the anterior region of the thigh were totally divided into five-layered divisions. 2) The cutaneous branches of each division including Rf or Cfl could be classified in three groups: the medial cutaneous branches (m), the anterior cutaneous branches (a), and the lateral cutaneous branches (l). Based on the above results, the branches could be described systematically. Parallelly, several accessory bundles of F penetrating the psoas major muscle were observed, and two types of accessory femoral nerves (F') could be distinguished: One was higher on the segmentation and mainly flew into the 1st division of F. While the other distributed only to the medial region of the thigh. To clarify the segmental or stratifical natures of the branches of each division, F', and the interrelations among them, analyses of the nerve fibers were undertaken under the operational microscope. Consequently, the segmental differences between the divisions were distinct, and the medial branches or F'm obviously contained ventral components. Thus, when a component originated from the higher segments, it distributed to the proximal region generally taking a superficial course; when it originated from the lower ones, it distributed to the distal region of the thigh forming the deeper division; when it belonged to the ventral stratum, it distributed to the medial region; and when it belonged to the dorsal stratum, it distributed to the lateral region. On the occasion of the fiber analysis, it was found that each root of the lumbar nerve was generally divided into two or three subsegmentally-arranged subroots that divided themselves into some fasciculi arranged micro-segmentally. A minute analysis of the segmentations of the nerves became possible because of the above characteristics.

Femoral Nerve↗

Anatomical study of the pudendal nerve adjacent to the sacrospinous ligament.

The pudendal nerve (S3-S5) is a major branch of the sacral plexus. After branching from the sacral plexus, the pudendal nerve travels through three main regions: the gluteal region, the pudendal canal, and the perineum. In the gluteal region, the pudendal nerve lies posterior to the sacrospinous ligament. The relationship of the pudendal nerve to the sacrospinous ligament has important clinical ramifications, but there is a lack of literature examining the variations in pudendal nerve anatomy in the gluteal region. This study investigates the pudendal nerve trunking in relation to the sacrospinous ligament in 37 cadavers (73 sides of pelves) of 21 males and 16 females, ranging from 18-83 years of age. Pudendal nerve trunking could be grouped into five types: Type I is defined as one-trunked (41/73; 56.2%), Type II is two-trunked (8/73; 11%), Type III is two-trunked with one trunk as an inferior rectal nerve piercing through the sacrospinous ligament (8/73; 11%), Type IV is two-trunked with one as an inferior rectal nerve not piercing through the sacrospinous ligament (7/73; 9.5%), and Type V is three-trunked (9/73; 12.3%). In summary, 56.2% of pudendal nerves adjacent to the sacrospinous ligament were one-trunked, 31.5% were two-trunked and 12.3% were three-trunked. Fifteen inferior rectal nerves originated independently from the S4 root and never joined the main pudendal nerve. Eight of fifteen inferior rectal nerves pierced through the sacrospinous ligament, perhaps making it prone for entrapment. We measured the average diameter of the main trunk of the pudendal nerve to be 4.67 +/- 1.17 mm. We also measured the average length of the pudendal nerve trunks before terminal branching to be 25.14 +/- 10.29 mm. There was no significant statistical difference in the average length, average diameter, number of trunks, and pudendal nerve variations between male and female or right or left sides of the pelves. A detailed study of pudendal nerve trunking in relationship to the sacrospinous ligament would be useful for instruction in basic anatomy courses and in relevant clinical settings as well.

Adolescent↗

Unusual cause of 'piriformis muscle syndrome'.

The piriformis muscle syndrome is a controversial "clinical" syndrome primarily characterized by signs and symptoms of sciatic nerve compression at the region of the piriformis muscle as it passes through the greater sciatic notch. The syndrome is often referred to; however, cases are rarely reported, and it is generally an uncommon diagnosis. Of those cases reported, the incidence is six times more frequent in females than in males, and is typically temporally related to minor pelvic or buttock trauma. We describe a case of a 40-year-old woman presenting with signs and symptoms suggestive of piriformis muscle syndrome following a gynecologic procedure performed in the dorsal lithotomy position. Electromyographic findings were consistent with this clinical entity. Operative exploration, however, revealed the source of neural compression to be a pseudoaneurysm of the inferior gluteal artery adjacent to the piriformis muscle. The diagnostic features of this clinical syndrome are discussed.

Adult↗