The median effective concentration of ropivacaine for ultrasound-guided anterior iliopsoas muscle space block in the elderly undergoing hip surgery: a dose-finding study.

Background: In order to improve perioperative pain and reduce the adverse outcome of severe pain in elderly hip fractures, anterior iliopsoas muscle space block (AIMSB) can be used clinically to reduce pain. The aim of the study is to investigate the 50% effective concentration (EC50) of ropivacaine for ultrasound-guided anterior iliopsoas space block in elderly with hip fracture. Methods: A total of 27 patients were enrolled with aged ≥65 years, American society of Anesthesiologists (ASA) physical status classification II-III and undergoing Total Hip Arthroplasty (THA). We measured the EC50 using Dixon's up-and-down method. Ultrasound-guided AIMSB was performed preoperatively with an initial concentration of 0.2% in the first patient. After a successful or unsuccessful postoperative analgesia, the concentration of local anesthetic was decreased or increased 0.05%, respectively in the next patient. The successful block effect was defined as no sensation to pinprick in the area with femoral nerve, obturator nerve, and lateral femoral cutaneous nerve in 30 min. Meanwhile, the EC50 of ropivacaine was determined by using linear model, linear-logarithmic model, probit regression model, and centered isotonic regression. Results: A total of 12 patients (48%) had a successful block. All patients with a successful block had a postoperative visual analog scale score of <4 in the 12 h. The estimated EC50 values in linear model, linear-logarithmic model, probit regression model, and centered isotonic regression (a nonparametric method) were 0.268%, 0.259%, 0.277%, and 0.289%. The residual standard error of linear model was the smallest (0.1245). Conclusion: The EC50 of ropivacaine in anterior iliopsoas space block under ultrasound guidance is 0.259-0.289%.

Position of lumbar plexus nerves in the psoas major: Application to transpsoas approaches to the lumbar spine.

Far lateral interbody fusion is a minimally invasive operating technique. However, the incidence of postoperative neurological complications is high, and some scholars question its safety. This study describes the neuroanatomical features and spatial orientation within the psoas major. Ten embalmed male cadavers were selected and the left psoas major was dissected. Subsequently, the area between the anterior and the posterior edges of the vertebral body was divided into three equal zones. The nerves' distribution, number, and spatial orientation of the L1/2 to L4/5 intervertebral discs were examined. A caliper was used to measure the diameter of the nerve. The safety zone of the L1/2 intervertebral disc level is located in zone I and II, the relative safe zones of the L2/3 and L4/5 intervertebral discs are located in zone II, and the safety zone of the L3/4 intervertebral disc level is located in the caudal side of zone II. The genitofemoral nerve exits the psoas major in a co-trunk or two-branch pattern, and its exit point was distributed between the L3 and L4 vertebral bodies, mainly at the L3/4 intervertebral disc level. The sympathetic ganglia in the psoas major appeared only in zone I at the L2/3 intervertebral disc level. This is a systematic anatomical study that describes the nerves of the psoas major. Spine surgeons can use this study-which consists of important clinical implications-for preoperative planning, and thus, reduce the risk of nerve injury during surgery.

Split unilateral del nervio femoral a nivel del músculo psoas mayor: reporte de caso / Unilateral femoral nerve split at the psoas major muscle: case report

RESUMEN: El nervio femoral (NF) es el mayor o ramo del plexo lumbar. Normalmente se origina de las divisiones posteriores del segundo al cuarto ramo anterior del plexo lumbar (L2-L4). El músculo psoas mayor tiene su origen a nivel de las vértebras T12 a L5, se fusiona con el músculo ilíaco para luego insertarse en el trocánter menor del fémur. Normalmente, a nivel de la pelvis menor el NF se encuentra entre los músculos ilíaco y psoas mayor. En este trabajo presentamos un caso donde el músculo psoas mayor se relaciona con divisiones o split del NF, esta es una rara variación en la división y curso del NF con relación al músculo psoas mayor. Se observó que el NF se dividía en dos ramos por sobre el plano del ligamento inguinal después de su origen en el plexo lumbar. El NF del lado izquierdo se formó por las ramas ventrales de L2 a L4, a nivel de L5 el nervio es perforado por fascículos del músculo psoas mayor. La división inferior del NF pasaba profundamente a las fibras del músculo iliopsoas y la división superior pasaba superficialmente al músculo psoas mayor y profundo a la fascia ilíaca. Después de un trayecto de 60,21 mm ambas divisiones se unieron, después de atrapar fibras músculo iliopsoas justo inmediatamente proximal al ligamento inguinal para formar el tronco del NF. Si bien las causas embriológicas de las variaciones de los nervios periféricos se remontan a la quinta y sexta semana de vida intrauterina, la expresión clínica de disfunciones neuromusculares aparecerá varios decenios después. De modo que los médicos de las áreas de la traumatología y neurología deben estar al tanto de tales variantes anatómicas para entender mejor el dolor y los síndromes asociados a la compresión nerviosa y durante las maniobras quirúrgicas en esta región.

SUMMARY: AbstractThe femoral nerve (NF) is the major branch (or ramus) of the lumbar plexus. It normally originates from the posterior divisions of the second to fourth anterior branches of the lumbar plexus (L2-L4). The psoas major muscle originates at the level of the T12 to L5 vertebrae, fuses with the iliacus muscle and then inserts into the lesser trochanter of the femur. Normally, at the level of the lesser pelvis, the NF is found between the iliacus and psoas major muscles. In this paper we present a case where the psoas major muscle is related to divisions or splitting of the NF, this is a rare variation in the division and course of the NF in relation to the psoas major muscle. The NF was observed to divide into two branches above the plane of the inguinal ligament after its origin in the lumbar plexus. The NF on the left side was formed by ventral branches from L2 to L4, at the level of L5 the nerve is perforated by fascicles of the psoas major muscle. The lower division of the NF passed deep to the fibers of the iliopsoas muscle and the upper division passed superficial to the psoas major muscle and deep to the iliac fascia. After a path of 60.21 mm both divisions joined, after trapping iliopsoas muscle fibers just immediately proximal to the inguinal ligament to form the NF trunk. While the embryological causes of peripheral nerve variations date back to the fifth and sixth week of intrauterine life, the clinical expression of neuromuscular dysfunctions will appear several decades later. Thus, physicians in the areas of traumatology and neurology should be aware of such anatomical variants to better understand pain and syndromes associated with nerve compression and during surgical maneuvers in this region.

Does the L5 spinal nerve move? Anatomical evaluation with implications for postoperative L5 nerve palsy.

PURPOSE: While palsy of the L5 nerve root due to stretch injury is a known complication in complex lumbosacral spine surgery, the underlying pathophysiology remains unclear. The goal of this cadaveric study was to quantify movement of the L5 nerve root during flexion/extension of the hip and lower lumbar spine. METHODS: Five fresh-frozen human cadavers were dissected on both sides to expose the lumbar vertebral bodies and the L5 nerve roots. Movement of the L5 nerve root was tested during flexion and extension of the hip and lower lumbar spine. Four steps were undertaken to characterize these movements: (1) removal of the bilateral psoas muscles, (2) removal of the lumbar vertebral bodies including the transforaminal ligaments from L3 to L5, (3) opening and removing the dura mater laterally to visualize the rootlets, and (4) removal of remaining soft tissue surrounding the L5 nerve root. Two metal bars were inserted into the sacral body at the level of S1 as fixed landmarks. The tips of these bars were connected to make a line for the ruler that was used to measure movement of the L5 nerve roots. Movement was regarded as measurable when there was an L5 nerve excursion of at least 1 mm. RESULTS: The mean age at death was 86.6 years (range 68-89 years). None of the four steps revealed any measurable movement after flexion/extension of the hip and lower lumbar spine on either side (< 1 mm). Flexion of the hip and lower lumbar spine revealed lax L5 nerve roots. Extension of the hip and lower lumbar spine showed taut ones. CONCLUSION: Significant movement or displacement of the L5 nerve root could not be quantified in this study. No mechanical cause for L5 nerve palsy could be identified so the etiology of the condition remains unclear.

Inadvertent epidural anesthesia associated with catheterization following continuous psoas compartment block in a patient with scoliosis: A Case report.

RATIONALE: Psoas compartment block (PCB) is typically performed using surface anatomical landmarks and neurostimulation for guidance. However, anatomical anomalies, such as scoliosis, make this technique unreliable, posing a challenge for the anesthesiologist when inducing regional anesthesia. PATIENT CONCERNS: A 69-year-old woman with lumbar scoliosis scheduled for total hip arthroplasty underwent PCB with catheterization. DIAGNOSES: Inadvertent epidural anesthesia with catheterization following PCB was diagnosed using a lumbar radiograph. INTERVENTIONS: Due to hypotension induced by local anesthetic (LA) epidural diffusion, the patient received intravenous hydration and vasopressor. Since bilateral sensory block was noted at the T3 level, with an incomplete motor blockade in both legs, the surgery was performed under epidural anesthesia. OUTCOMES: The patient remained hemodynamically stable throughout the duration of the surgical procedure. The surgery was uneventful and without further complications. LESSONS: Patients with lumbar scoliosis are highly at risk of LA epidural diffusion, following PCB using traditional landmark-based approach. Other nerve-localizing technique can minimize the risk of this complication.

Femoral neuropathy following a psoas hitch vesicopexy.

A 68-year-old man classified as III on the American Society of Anaesthesiologists (ASA) physical status classification system, with a high-grade papillary urothelial cell carcinoma of the left distal ureter, underwent open retroperitoneal distal ureterectomy followed by a ureteroneocystostomy with a vesico-psoas hitch. Postoperatively, the patient complained of left proximal lower limb weakness, severe pain and hypaesthesia of the ventral left thigh suggestive of femoral neuropathy. After excluding common causes for postsurgical pain, a surgical re-exploration was eventually performed during which the sutures used in the vesicopexy were removed, resulting in almost complete resolution of the symptoms. Electromyographic analysis 4 weeks after discharge confirmed the diagnosis of femoral neuropathy, most likely caused by the sutures used in the vesicopexy. This is a rare complication with major consequences for postoperative recovery.

Psoas compartment and sacral plexus block via electrostimulation for pelvic limb amputation in dogs.

OBJECTIVE: To assess the efficacy of psoas compartment and sacral plexus block for pelvic limb amputation in dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: A total of 16 dogs aged 8±3 years and weighing 35±14 kg (mean±standard deviation). METHODS: Dogs were administered morphine (0.5 mg kg-1) and atropine (0.02 mg kg-1); anesthesia was induced with propofol and maintained with isoflurane. Regional blocks were performed before surgery in eight dogs with bupivacaine (2.2 mg kg-1) and eight dogs were administered an equivalent volume of saline. The lumbar plexus within the psoas compartment was identified using electrolocation lateral to the lumbar vertebrae at the fourth-fifth, fifth-sixth and sixth-seventh vertebral interspaces. The sacral plexus, ventrolateral to the sacrum, was identified using electrolocation. Anesthesia was monitored using heart rate (HR), invasive blood pressure, electrocardiography, expired gases, respiratory frequency and esophageal temperature by an investigator unaware of the group allocation. Pelvic limb amputation by coxofemoral disarticulation was performed. Dogs that responded to surgical stimulation (>10% increase in HR or arterial pressure) were administered fentanyl (2 µg kg-1) intravenously for rescue analgesia. Postoperative pain was assessed at extubation; 30, 60 and 120 minutes; and the morning after surgery using a visual analog scale (VAS). RESULTS: The number of intraoperative fentanyl doses was fewer in the bupivacaine group (2.7±1.1 versus 6.0±2.2; p<0.01). Differences in physiologic variables were not clinically significant. VAS scores were lower in bupivacaine dogs at extubation (0.8±1.9 versus 3.8±2.5) and at 30 minutes (1.0±1.4 versus 4.3±2.1; p<0.05). CONCLUSIONS AND CLINICAL RELEVANCE: Psoas compartment (lumbar plexus) and sacral plexus block provided analgesia during pelvic limb amputation in dogs.

Anatomy of psoas muscle innervation: Cadaveric study.

Hip flexion weakness is relatively common after lateral transpsoas surgery. Persistent weakness may result from injury to the innervation of the psoas major muscles (PMMs); however, anatomical texts have conflicting descriptions of this innervation, and the branching pattern of the nerves within the psoas major, particularly relative to vertebral anatomy, has not been described. The authors dissected human cadavers to describe the branching pattern of nerves supplying the PMMs. Sixteen embalmed cadavers were dissected, and the fine branching pattern of the innervation to the PMM was studied in 24 specimens. The number of branches and width and length of each branch of nerves to the PMMs were quantified. Nerve branches innervating the PMMs arose from spinal nerve levels L1-L4, with an average of 6.3 ± 1.1 branches per muscle. The L1 nerve branch was the least consistently present, whereas L2 and L3 branches were the most robust, the most numerous, and always present. The nerve branches to the psoas major commonly crossed the intervertebral (IV) disc obliquely prior to ramification within the muscle; 76%, 80%, and 40% of specimens had a branch to the PMM cross the midportion of the L2-3, L3-4, and L4-5 IV discs, respectively. The PMMs are segmentally innervated from the L2-L4 ventral rami branches, where these branches course obliquely across the L2-3, L3-4, and L4-5 IV discs. Knowledge of the mapping of nerve branches to the PMMs may reduce injury and the incidence of persistent weak hip flexion during lateral transpsoas surgery. Clin. Anat. 30:479-486, 2017. © 2017 Wiley Periodicals, Inc.

Ultrasound-Guided Quadratus Lumborum Block: An Updated Review of Anatomy and Techniques.

Purpose of Review. Since the original publication on the quadratus lumborum (QL) block, the technique has evolved significantly during the last decade. This review highlights recent advances in various approaches for administering the QL block and proposes directions for future research. Recent Findings. The QL block findings continue to become clearer. We now understand that the QL block has several approach methods (anterior, lateral, posterior, and intramuscular) and the spread of local anesthetic varies with each approach. In particular, dye injected using the anterior QL block approach spread to the L1, L2, and L3 nerve roots and within psoas major and QL muscles. Summary. The QL block is an effective analgesic tool for abdominal surgery. However, the best approach is yet to be determined. Therefore, the anesthetic spread of the several QL blocks must be made clear.

Ultrasound-guided psoas compartment block and general anesthesia for arthroscopic knee surgery: a case report.

Anesthetizing the lumbar plexus at its origin facilitates a more "complete" psoas compartment block compared to peripheral approaches. It is usually performed using surface anatomical landmarks, and the site for local anesthetic injection is confirmed by observing quadriceps muscle contraction to peripheral nerve stimulation. Ultrasound may provide guidance alone or together with the aid of nerve stimulation during nerve blocks. We present a 48-year-old male patient, American Society of Anesthesiologists (ASA) physical status II, who refused spinal anesthesia, and underwent knee arthroscopy with ultrasound-guided psoas compartment block and general anesthesia. Following the standard monitoring and lateral decubitus positioning, the vertebral body, psoas, erector spinae, and quadratus lumborum muscles and hyperechoic nerve roots of the patient were visualized at the level of L4-5 with curvilinear ultrasound probe. The needle was inserted with ultrasound guidance, and correct tip position was confirmed with quadriceps contraction. Then, the mixture of 30 mL local anesthetic (10 mL 2% lidocaine and 20 ml 5% levobupivacaine) was injected at the estimated position of the lumbar plexus (junction of the posterior third and anterior two-thirds of the psoas muscle). He also received general anesthesia for the surgery. Anesthesia and surgical procedures were completed successfully without any additional anesthetic/analgesic requirement or complication. The postoperative period was pain-free both at rest and during mobilization for 24 hours. This case report shows that ultrasound-guided psoas compartment block is feasible and efficient for peri- and postoperative analgesia during knee arthroscopy.

Safe zone for retractor placement to the lumbar spine via the transpsoas approach.

PURPOSE: To measure anatomic variations of the lumbar plexus within the psoas in relation to the L2/3, L3/4, and L4/5 disc spaces and to delineate a safe zone to avoid nerve injury during retractor placement via the transpsoas approach. METHODS: Six male and 6 female cadavers (24 psoas/ lumbar plexuses) aged 35 to 74 years were dissected. The lumbar plexus was isolated bilaterally. The L2, L3, and L4 nerve roots were identified and isolated without disturbing their natural anatomic course. The anteroposterior (AP) diameter of each intervertebral disc at L2/3, L3/4, and L4/5 was used as a reference. Four measurements were made using a caliper: the AP and mediolateral (ML) diameters of the psoas and AP and ML excursions of each nerve root. Percentages were calculated for the 4 measurements using the reference of the AP diameter of the intervertebral disc at each level. Comparison between left and right sides, between males and females, and between excursions of nerve roots were made. RESULTS: The AP diameter of the psoas increased from L2 to L4, with a mean vertebral body coverage of 80%, 86%, and 85% at L2/3, L3/4, and L4/5, respectively. Both the L2 and L3 nerve roots demonstrated substantial anterior trajectories as they coursed distally in the lumbar spine. No nerve root encroached anteriorly beyond 33% of the intervertebral disc space at L2 to L5. CONCLUSION: The lumbar plexus area corresponding to the anterior half of the intervertebral disc was the safe zone. Procedures to the lumbar spine via the transpsoas approach should be performed within the safe zone to avoid nerve injury.

Abdominal wall trigger point case study.

Myofascial trigger points (TrPs) are posited to be an element in the etiology of both musculoskeletal and visceral pain. However, the recognition of TrPs as a causative factor in a patient's pain presentation varies amongst physicians and therapists. When myofascial pain syndrome is responsible for a patient's condition and is not recognized by the patient's medical advisors, the patient may be put through a plethora of testing procedures to find the cause of the patient's pain, and prescribed medications in an effort to treat the patient's symptoms. The case review presented here involves a patient with severe anterior abdominal pain, with a history of Crohn's disease, who experienced a long and difficult medical process before a diagnosis of myofascial pain syndrome was made.

Motor nerve injuries following the minimally invasive lateral transpsoas approach.

OBJECT: The aim of this study was to determine the incidence of motor nerve injuries during the minimally invasive lateral interbody fusion procedure at a single academic medical center. METHODS: A retrospective chart review of 118 patients who had undergone lateral interbody fusion was performed. Both inpatient and outpatient records were examined to identify any new postoperative motor weakness in the lower extremities and abdominal wall musculature that was attributable to the operative procedure. RESULTS: In the period from 2007 to 2011 the lateral interbody fusion procedure was attempted on 201 lumbar intervertebral disc levels. No femoral nerve injuries occurred at any disc level other than the L4-5 disc space. Among procedures involving the L4-5 level there were 2 femoral nerve injuries, corresponding to a 4.8% injury risk at this level as compared with a 0% injury risk at other lumbar spine levels. Five patients (4.2%) had postoperative abdominal flank bulge attributable to injury to the abdominal wall motor innervation. CONCLUSIONS: The overall incidence of femoral nerve injury after the lateral transpsoas approach was 1.7%; however, the level-specific incidence was 4.8% for procedures performed at the L4-5 disc space. Approximately 4% of patients had postoperative abdominal flank bulge. Surgeons will be able to minimize these motor nerve injuries through judicious use of the procedure at the L4-5 level and careful attention to the T-11 and T-12 motor nerves during exposure and closure of the abdominal wall.

The lumbosacral plexus: anatomic considerations for minimally invasive retroperitoneal transpsoas approach.

PURPOSE: The minimally invasive transpsoas approach can be employed to treat various spinal disorders, such as disc degeneration, deformity, and lateral disc herniation. With this technique, visualization is limited in comparison with the open procedure and the proximity of the lumbar plexus to the surgical pathway is one limitation of this technique. Precise knowledge of the regional anatomy of the lumbar plexus is required for safe passage through the psoas muscle. The primary objective of this study was to determine the anatomic position of the lumbar plexus branches and sympathetic chain in relation to the intervertebral disc and to define a safe working zone. The second objective was to compare our observations with previous anatomical studies concerning the transpsoas approach. METHODS: A total of 60 lumbar plexus in 8 fresh cadavers from the Department of Anatomy were analyzed in this study. Coronal and lateral X-Ray images were obtained before dissection in order to eliminate spine deformity or fracture. All cadavers were placed in a lateral decubitus position with a lateral bolster. Dissection of the lumbar plexus was performed. All nerve branches and sympathetic chain were identified. Intervertebral disc space from L1L2 to L4L5 was divided into four zones. Zone 1 being the anterior quarter of the disc, zone 2 being the middle anterior quarter, zone 3 the posterior middle quarter and zone 4 the posterior quarter. Crossing of each nervous branch with the disc was reported and a safe working zone was determined for L1L2 to L4L5 disc levels. A safe working zone was defined by the absence of crossing of a lumbar plexus branch. RESULTS: No anatomical variation was found during blunt dissection. As described previously, the lumbar plexus is composed of the ventral divisions of the first four lumbar nerves and from contributions of the sub costal nerve from T12. The safe working zone includes zones 2 and 3 at level L1L2, zone 3 at level L2L3, zone 3 at level L3L4, and zone 2 at level L4L5. No difference was observed between right and left sides as regards the relationships between the lumbar plexus and the intervertebral disc. CONCLUSION: We observed some differences concerning the safe working zone in comparison with other cadaveric studies. The small number of cadaveric specimens used in anatomical studies probably explains theses differences. The minimally invasive transpsoas lateral approach was initially developed to reduce the complications associated with the traditional procedure. The anatomical relationships between the lumbar plexus and the intervertebral disc make this technique particularly risky a L4L5. Alternative techniques, such as transforaminal interbody fusion (TLIF), posterior lumbar interbody fusion (PLIF) or anterior interbody fusion (ALIF) should be used at this level.

Critical analysis of extra peritoneal antero-lateral approach for lumbar plexus / Análise crítica do acesso anterolateral retroperitoneal ao plexo lombar

Lesions of lumbar plexus are uncommon and descriptions of surgical access are derived from vertebral spine approaches. METHOD: The extraperitoneal anterolateral approach to the lumbar plexus was performed in six adult fresh cadavers. The difficulties on dissection were related. RESULTS: An exposure of all distal elements of lumbar plexus was possible, but a cranial extension of the incision was needed to reach the iliohypogastric nerve in all cases. Ligation of vessels derived from common iliac artery was necessary for genitofemoral and obturator nerves exposure in two cases. The most proximal part of the lumbar roots could be identified only after dissection and clipping of most lumbar vessels. CONCLUSION: The extraperitoneal anterolateral approach allows appropriate exposure of terminal nerves of lumbar plexus laterallly to psoas major muscle. Cranial extension of the cutaneous incision may be necessary for exposure of iliohypogastric nerve. Roots exposure increases the risk of vascular damage.

As lesões do plexo lombar são incomuns e as descrições dos acessos cirúrgicos são derivadas de vias de acesso à coluna vertebral. MÉTODO: A via extraperitoneal anterolateral foi realizada em seis cadáveres para o acesso ao plexo lombar. Eventuais dificuldades na dissecção foram relatadas. RESULTADOS: Tal acesso permitiu a exposição dos elementos distais do plexo lombar, mas uma extensão cranial da incisão foi necessária para a exposição do nervo iliohipogástrico. Para a exposição dos nervos genitofemoral e obturador houve a necessidade da ligadura de vasos originados da artéria ilíaca comum em 2 casos. As raízes foram identificadas somente após dissecção e ligadura dos vasos lombares. CONCLUSÃO: O acesso anterolateral extraperitoneal permite uma exposição adequada dos nervos terminais do plexo lombar lateralmente ao músculo psoas maior. Uma extensão cranial da incisão pode ser necessária para exposição do nervo iliohipogástrico. A exposição das raízes implica em maior risco de lesão vascular.

Psoas compartment block for acute postoperative pain management after hip surgery in pediatrics: a comparative study with caudal analgesia.

BACKGROUND: Lower-limb peripheral nerve blocks in pediatrics have gained much more popularity in the last few decades. Our purpose of this study was to compare the postoperative analgesic effects between psoas compartment block (PCB) and caudal block in small children undergoing open hip reduction/osteotomies. METHODS: Forty American Society of Anesthesiologists physical status I-II children aged 1 to 6 years planned to undergo open hip reduction/osteotomies were administered general anesthesia and then randomly assigned to receive 1 of 2 regional anesthetics: caudal block (group C, n=20) or PCB (group P, n=20). Ropivacaine 0.25% with epinephrine (5 µg/mL) was used in both blocks. The primary outcome of the study was the total consumption of morphine in the first 24 postoperative hrs. Secondary outcomes included dose of intraoperative fentanyl, occurrence of intraoperative hypotension or bradycardia, postoperative pain scores, time to first morphine analgesia, and occurrence of postoperative vomiting or urine retention. RESULTS: The cumulative dose of morphine administered in the ward in the first postoperative 24 hrs and the time to first rescue morphine dose were higher in group C than in group P (P<0.001). There were no differences between the 2 groups regarding intraoperative and postoperative complications except for the incidence of urine retention, which was higher in group C than in group P (P=0.037). CONCLUSIONS: Use of single-shot PCB is superior to single-shot caudal block regarding length of postoperative analgesia and cumulative dose of morphine in small children undergoing open hip reduction/osteotomies.

Dynamically evoked, discrete-threshold electromyography in the extreme lateral interbody fusion approach.

OBJECT: because the psoas muscle, which contains nerves of the lumbar plexus, is traversed during the extreme lateral interbody fusion (XLIF) approach, appropriate nerve monitoring is needed to avoid nerve injury during surgery and prevent approach-related neural deficit. This study was performed to assess the effectiveness of dynamically evoked electromyography (EMG) to detect and prevent neural injury during the XLIF approach. METHODS: one hundred two patients undergoing XLIF at L3-4 and/or L4-5 were enrolled in a prospective, multicenter, nonrandomized clinical study. The EMG threshold values for each of the 3 successive dilators were recorded at the surface of the psoas muscle, mid-psoas, and on the spine. At each location, the dilators were rotated 360°, taking recordings immediately posterior, superior, anterior, and inferior. For each dilator, the authors noted the rotational position (the angle in degrees) at which the lowest threshold was found. Findings of pre- and postoperative neurological examinations were also recorded. RESULTS: nerves were identified within proximity of the dilators (alert-level EMG feedback) in 55.7% of all cases during the XLIF approach. Although nerves were more commonly identified in the posterior margin (63%), there was significant variability in the location of nerves identified. Despite the fact that the posterior half of the disc space was targeted in 90% of cases, no significant long-lasting neural deficits were identified in any case; 27.5% experienced new iliopsoas/hip flexion weakness and 17.6% experienced new postoperative upper medial thigh sensory loss. Transient motor deficits were identified in 3 patients (2.9%), and all had resolved by the 6-month follow-up visit. CONCLUSIONS: the ability to identify and report a discrete, real-time EMG threshold during the transpsoas approach helps to avoid nerve injury and is required for the safe performance of the XLIF procedure. Additionally, nerve location is variable, thus reinforcing the need for real-time directional and proximity information.