Iatrogenic femoral neuropathy: two cases and literature update

Femoral neuropathy: A clinical and electrodiagnostic review

INTRODUCTION/AIMS

Femoral neuropathies can cause severe, prolonged debility, yet there have been few clinical and electrodiagnostic (EDx) studies addressing this condition. The aim of this study was to better understand the etiologies, EDx features, and clinical course of femoral neuropathy.

METHODS

We identified patients evaluated at Mayo Clinic Rochester between January 1, 1999 and July 31, 2019, with possible new femoral neuropathy ascertained via International Classification of Diseases-versions 9 and 10 diagnosis codes presenting within 6 months of symptom onset.

RESULTS

A retrospective review of 1084 records was performed and we ultimately identified 159 patients with isolated femoral neuropathy for inclusion. The most common femoral neuropathy etiologies were compressive (40%), perioperative stretch (35%), and inflammatory (6%). Presenting symptoms included weakness (96%), sensory loss (73%), and pain (53%). Presenting motor physical exam findings demonstrated moderate weakness (34%) or no activation (25%) of knee extension and mild (32%) or moderate (35%) weakness of hip flexion. Seventy-two percent of patients underwent EDx testing, including 22 with femoral motor nerve conduction studies. Treatment often involved physical therapy (89%) and was otherwise etiology-specific. In patients with follow-up data available (n = 154), 83% had subjective clinical improvement at follow-up with a mean time to initial improvement of 3.3 months and mean time to recovery at final follow-up of 14.8 months. Only 48% of patients had nearly complete or complete recovery.

DISCUSSION

In our cohort, the most common etiologies of femoral neuropathy were compression or perioperative stretch with high initial morbidity. Although motor recovery is common, improvement is often prolonged and incomplete.

Femoral Nerve Palsy Post Total Hip Arthroplasty (THA) via a Posterolateral Approach

Femoral nerve palsy (FNP) is a debilitating and relatively rare complication of total hip replacement, which can worsen the functional prognosis. Various surgical approaches, including posterior, lateral, and anterior, are employed in total hip arthroplasty (THA), and the chosen approach can influence which nerve is affected. There is currently a lack of recent research on the prevalence of FNP and its typical course of recovery. In this clinical case, we report a rare incidence of FNP that presented as a complication of primary THA in a patient with end-stage osteoarthritis secondary to developmental dysplasia of the hip (DDH). A 35-year-old female presented with groin pain and restricted movement in her hip joint. She had a history of undergoing complex open-reduction surgery for hip dysplasia. During the physical examination, a positive Trendelenburg gait was identified, along with end-stage osteoarthritis (OA) secondary to the dysplasia. She subsequently underwent THA using a posterolateral approach. Following the procedure, she experienced neurological symptoms, leading to the diagnosis of FNP, a rare occurrence.

Applying graph theory to improve the quality of scientific evidence from textual information: Neural injuries after gynaecologic pelvic surgery for genital prolapse and urinary incontinence

AIMS

To provide the overall rate for all types of neurologic iatrogenic injuries during urogynaecologic surgery from textual data.

METHODS

Systematic research focused on complications of gynaecologic surgery and neurologic injuries in abstracts. Keywords concerning complications (cluster A), unspecific; neurologic issues (cluster B); surgery (generic words) (cluster C); specific gynaecologic operations (cluster D); and specific gynaecologic operations for pelvic organ prolapse and urinary incontinence (cluster E) were extracted. Associations among clusters of keywords were assessed by using multiple runs of text-mining software Semantic Brand Score (SBS, https://semanticbrandscore.com/#primary). Association scores were converted into probabilities. The rate of neurologic complications in urogynaecologic surgery was calculated ("a priori" probability) by applying Bayes' theorem. Textual estimates of neurological injuries in urogynaecologic surgery are 0.035554 (95% confidence intervals 0.019607-0.0515001; no quantitative data were found). To test if the probability calculated on textual information was the same as quantitative data reports ("a posteriori" probability), the rate of neurologic complication of all gynaecologic surgery was calculated using a meta-analytics approach and was compared with the textual analysis value.

RESULTS

The rate of neurologic complications in gynaecologic surgery after meta-analytic data synthesis has been 0.016489 (95% confidence intervals 0.012163-0.022320), which is equal to the textual estimate (0.016889, 95% confidence intervals 0.019607-0.051501). Therefore, 0.035554 is a reliable likelihood to observe a neurologic complication in urogynaecologic surgery.

CONCLUSION

Iatrogenic nerve injuries in urogynaecologic surgery are higher than whole gynaecologic surgery. Text-mining software SBS and probability conversion can provide reliable answers from overall scholars' opinions on unsolved clinical questions when better evidence is lacking.

The epidemiology and management of iliopsoas hematoma with femoral nerve palsy: A descriptive systematic review of 174 cases

INTRODUCTION

Iliopsoas hematoma with femoral nerve palsy is a rare phenomenon with no consensus treatment algorithm. The objective of this study was to perform a systematic review of all reported cases of femoral nerve palsy secondary to iliopsoas hematoma to better elucidate it's optimal treatment.

MATERIALS AND METHODS

Queries of the PubMed, Embase, and Cochrane databases were performed for reports available in English of femoral nerve palsy secondary to iliopsoas, psoas, or iliacus hematoma. 1491 articles were identified. After removal of duplicated publications and review of abstract titles via a majority reviewer consensus, 217 articles remained for consideration. Dedicated review of the remaining articles (including their reference sections) yielded 122 articles representing 174 distinct cases. Clinical data including patient age, sex, medical history, use of pharmacologic anticoagulation, sensory and motor examination at presentation and follow-up, hematoma etiology and location, time to intervention, and type of intervention were collected. Descriptive statistics were generated for each variable.

RESULTS

Femoral nerve palsy secondary to iliopsoas hematoma occurred at a mean age of 44.5 years old. A majority of patients (60%) were male, and a majority of hematomas (54%) occurred due to pharmacologic anticoagulation. Most hematomas (57%) were treated conservatively, and almost half (49%) - regardless of treatment modality - resulted in persistent motor deficits at final follow-up. A minority of patients treated surgically (34%) had residual motor deficit at final follow-up, while 66% of those treated medically had resultant motor deficits, although no direct statistical comparison was able to be performed.

DISCUSSION AND CONCLUSIONS

The disparate available data on iliopsoas hematoma with femoral nerve palsy precludes the completion of a true metanalysis, and therefore any conclusions on an optimal treatment algorithm. Based on review of the literature, small to moderate hematomas are often treated conservatively, while larger hematomas with progressive neurological symptoms are usually managed with a percutaneous decompression or surgery.

LEVEL OF EVIDENCE

IV.

[Meralgia paraesthetica as complication of patient positioning : A not fully controllable risk]

Als Meralgia paraesthetica (MP) bezeichnet man eine zu den neurologischen Engpasssyndromen zählende Schädigung des aus dem Plexus lumbalis entspringenden sensiblen N. cutaneus femoris lateralis. Symptome sind temporäre oder bleibende Parästhesien und Schmerzen an der Vorder- und Außenseite des Oberschenkels. Die MP kann idiopathisch auftreten, sich genuin als z. B. „seat belt syndrome“ oder „Jeans-Syndrom“ verwirklichen, sie kann aber auch Folge eines operativen Eingriffs oder einer chirurgischen bzw. intensivmedizinischen Lagerung sein. Im Fokus stehen hierbei in der Literatur die Steinschnitt-, die Bauch- und die „Beach-chair“-Lagerung.

Analysiert wurden 21 Beschwerden über eine postoperativ erstmals aufgetretene MP, die bei der Gutachterkommission für ärztliche Behandlungsfehler bei der Ärztekammer Nordrhein im Verlauf der letzten 10 Jahre eingereicht wurden. Unter diesen konnten 6 Fälle als Lagerungsschaden nach Steinschnittlagerung identifiziert werden; in 3 Fällen trat eine MP nach Rückenlagerung auf; die Ätiologie konnte nicht sicher geklärt werden. In 12 Fällen wurde die MP als direkte Operationskomplikation erkannt.

Pathophysiologie, Inzidenz und Verlauf sowie juristische Implikationen der lagerungsbedingten MP werden beschrieben. Als hauptsächlicher Pathomechanismus wird eine Druckschädigung des Nervs an seiner Kreuzungsstelle mit dem Leistenband diskutiert. Wenngleich alle hier vorgestellten Fälle nach der Steinschnittlagerung auftraten, scheint sich die Komplikation nach Literaturdaten auch bei anderen Lagerungsarten, am häufigsten möglicherweise bei Bauchlagerungen, zu verwirklichen. Dies erklärt auch die zunehmenden Fallberichte einer MP nach Bauchlagerung bei COVID-19-Patient*innen. Eine sichere Vermeidung der lagerungsbedingten Komplikation erscheint aufgrund der anatomischen Variabilität des Nervenverlaufs und der unklaren Pathomechanismen nicht möglich.

Reconstruction of Quadriceps Function Using a Single Functional Gracilis Muscle Transfer With an Adductor Longus Nerve to Femoral Nerve Branch of the Rectus Femoris Nerve Transfer

BACKGROUND

A femoral nerve injury may result in cutaneous sensory disturbances of the anteromedial thigh and complete paralysis of the quadriceps femoris muscles resulting in an inability to extend the knee. The traditional mainstay of treatment for femoral neuropathy is early physiotherapy, knee support devices, and pain control. Case reports have used the anterior division of the obturator nerve as a donor nerve to innervate the quadriceps femoris muscles; however, a second nerve transfer or nerve grafting is often required for improved outcomes. We suggest a novel technique of combining an innervated, pedicled gracilis transfer with an adductor longus to rectus femoris nerve transfer to restore the strength and stability of the quadriceps muscles.

METHODS

This is a case series describing the use of a pedicled gracilis muscle transposed into the rectus femoris position with a concomitant nerve transfer from the adductor longus nerve branch into the rectus femoris nerve branch to restore quadriceps function after iatrogenic injury (hip arthroplasty) and trauma (gunshot wound).

RESULTS

With electrodiagnostic confirmation of severe denervation of the quadriceps muscles and no evidence of elicitable motor units, 2 patients (average age, 47 years) underwent a quadriceps muscle reconstruction with a pedicled, innervated gracilis muscle and an adductor longus to recuts femoris nerve transfer. At 1 year follow-up, the patients achieved 4.5/5 British Medical Research Council full knee extension, a stable knee, and the ability to ambulate without an assistive aid.

CONCLUSIONS

The required amount of quadriceps strength necessary to maintain quality of life has not been accurately established. In the case of femoral neuropathy, we assumed that a nerve transfer alone and a gracilis muscle transfer alone would not provide enough stability and strength to restore quadriceps function. We believe that the restoration of the quadriceps function after femoral nerve injury can be achieved by combining an innervated, pedicled gracilis transfer with an adductor longus to rectus femoris nerve transfer with low morbidity and no donor defects.

Contemporary Approaches to Peripheral Nerve Surgery

“State of the Art” Learning Objectives: This manuscript serves to provide the reader with a general overview of the contemporary approaches to peripheral nerve reconstruction as the field has undergone considerable advancement over the last 3 decades. The learning objectives are as follows: To provide the reader with a brief history of peripheral nerve surgery and some of the landmark developments that allow for current peripheral nerve care practices. To outline the considerations and management options for the care of patients with brachial plexopathy, spinal cord injury, and lower extremity peripheral nerve injury. Highlight contemporary surgical techniques to address terminal neuroma and phantom limb pain. Review progressive and future procedures in peripheral nerve care, such as supercharge end-to-side nerve transfers. Discuss rehabilitation techniques for peripheral nerve care.

Variability in rod to bone distance needed in pelvic subcutaneous internal fixation to avoid nerve compression: A tridimensional population-based study

INTRODUCTION

Pelvic internal fixation has become a popular method for treatment of unstable pelvic ring injuries. Although successful, one complication is femoral nerve palsy from compression of the connecting rod. In light of this complication, this study was designed to evaluate sagittal inclinations of the rod and the feasibility of using a rod with a constant curvature.

HYPOTHESIS

It is hypothesized that that there is a connection between the sagittal inclination of the rod and the rod to bone distance, as well as single rod can be contoured with a constant curvature to be used in the majority of all patients.

METHODS

Three dimensional models of pelvis CTs from a single level 1 trauma center were created and imported into a program where software superimposed a pre-contoured rod in the sagittal planes upon the pelvic slices. The sagittal inclination was deemed acceptable is no interference occurred between the area of compression risk and the rod. For each pelvis and considered sagittal rod inclination, the rod radius of curvature (ROC), minimal rod to bone distance (RTB) and transverse inclinations (φ_L and φ_R) were measured at which the pedicle screws should be inserted to follow the direction of the smallest RTB.

RESULTS

The sagittal inclinations feasible for all subjects were between 15° to 30°. In this sagittal range, the average RTB varied in values ranging from 4.0±0.9mm to 25.4±11.4mm (p<0.01). Only 46% of subjects allowed a rod with constant curvature.

DISCUSSION AND CONCLUSION

Our study found that a rod to bone distance of 15mm was not safe for all models. As well, many subject models did not allow placement of pre-contoured rod. Patient specific templating of pelvic subcutaneous internal fixation is strictly needed to limit complications.

LEVEL OF EVIDENCE

VII; Basic Science.

Iliopsoas hematoma presenting with sudden knee extensor weakness: A case report

RATIONALE

Hematoma of the iliopsoas muscle is a rare condition. Prolonged pressure conditions due to hematoma of the femoral nerve can cause severe pain in the affected groin, hip, and thigh, and quadriceps weakness. We report a rare case of a spontaneous iliopsoas muscle hematoma that caused sudden femoral neuropathy.

PATIENT CONCERNS

A 71-year-old woman presented sudden left hip pain and knee extensor weakness. The pain was aggravated with left hip extension. She had a bilateral total hip replacement surgery due to avascular necrosis. She was diagnosed as mild stenosis of the cerebral artery and took aspirin to prevent cerebral artery atherosclerosis.

DIAGNOSIS

A hip computed tomography scan demonstrated a suspicious fluid collection at the left iliopsoas bursa. We considered the possibility of lower limb weakness due to neuralgic amyotrophy and performed electromyography and enhanced lumbosacral magnetic resonance imaging (MRI). Electromyography finding showed left femoral neuropathy of moderate severity around the inguinal area was diagnosed. On MRI, left iliopsoas bursitis or hematoma, and displacement of the left femoral nerve due to the iliopsoas bursitis/hematoma were observed.

INTERVENTION

Ultrasonography (US)-guided aspiration of the left iliopsoas hematoma was performed. We started steroid pulse therapy for 8 days.

OUTCOMES

After US-guided aspiration and steroid pulse therapy, the patient's knee extension motor grade improved from grade 1 to 2, and the pain was slightly reduced. At 3 weeks after the aspiration procedure, her hip flexion motor grade had improved from grade 3+ to 4 at follow-up.

LESSONS

Imaging studies are fundamental to diagnose of iliopsoas hematoma. Electromyography examination plays an important role in determining the prognosis of patients and lesion site. Despite the negligible change in sitting position, hematoma can develop. Physicians should consider hematoma that cause femoral neuropathy.

Integrative Review of Lower Extremity Nerve Injury During Vaginal Birth

OBJECTIVE

To describe the incidence, health effects, risk factors, and practice implications of lower extremity nerve injury (LENI) related to vaginal births.

DATA SOURCES

We searched MEDLINE, CINAHL, and PubMed from 2000 to 2020 for peer-reviewed published case reports and research studies of LENI related to vaginal births.

STUDY SELECTION

We identified 188 potential records, and 20 met inclusion criteria (six research studies and 14 case studies).

DATA EXTRACTION

Three independent reviewers extracted details of injuries and births into an Excel spreadsheet and analyzed data using SPSS.

DATA SYNTHESIS

Using birth data from each case study and from four of the six research articles, we found the incidence of LENI in vaginal births was 0.3% to 1.8%. The description of health effects includes affected nerves and the location, description, and duration of symptoms. Analyses of risk factors were limited by missing birth data (length of second stage, birth weight, etc). Vaginal births with LENI were 76% spontaneous, 77% with neuraxial anesthesia, and 64% first vaginal birth. Practice implications focused on prevention through specific positioning strategies. Despite nurses being the primary caregivers during labor, LENI was reported most often in anesthesia journals with virtually no reports in nursing journals.

CONCLUSION

LENI is a potential complication of vaginal birth, and little published research is available on prevention and prognosis. While obstetric and anesthesia factors can cause or contribute to nerve injury, LENI is usually caused by positioning and is considered preventable. Care recommendations include the following: avoid prolonged hyperflexion of women's thighs and knees; minimize time in lithotomy, squatting, or kneeling positions; prevent hand or other deep pressure on lateral knee and posterior thigh areas; avoid motor-blocking neuraxial (epidural) anesthesia; and implement frequent repositioning. The paucity of literature contributes to the lack of awareness of LENI among clinicians.

Transient pelvic limb neuropathy following proximal metatarsal and tarsal magnetic resonance imaging in seven horses

BACKGROUND

Pelvic limb neuropathy is a rare post-anaesthetic complication. In the authors' experiences, the incidence of post-anaesthesia neuropathy is increased following MRI of the proximal metatarsus and tarsal regions when compared with previously reported incidences of post-anaesthetic neuropathy.

OBJECTIVES

This study reports the incidence, diagnosis, treatment and outcome of seven horses with post-anaesthesia neuropathy following proximal metatarsal and tarsal MRI.

STUDY DESIGN

Retrospective case series.

METHODS

Case record review of horses receiving general anaesthesia for MRI between 1 January 2012 and 31 December 2017.

RESULTS

A total of 1134 MRI procedures were performed and reviewed for analysis. Eight cases of neuropathy were identified in 1088 limb scans (0.74%). Of these cases, one was subsequent to thoracic limb imaging (1/834; 0.12%) and seven were subsequent to imaging of proximal metatarsal and/or tarsal structures (7/181; 3.9%). Following proximal metatarsal and/or tarsal MRI, transient nondependent limb femoral neuropathy developed in six of the seven affected horses, with one additional horse developing peroneal neuropathy of the dependent limb. Recovery of pelvic limb function occurred within 72 h and 9 days in six and one horse, respectively.

MAIN LIMITATIONS

Anaesthetic protocol and neuropathy treatment for the affected horses were not standardised.

CONCLUSIONS

Though an uncommon complication in horses, transient neuropathy may occur more frequently following MRI of the proximal metatarsal and tarsal structures when compared with other MRI scans. This may be due to patient positioning and the requirement for limb traction for MRI of more proximal regions. Supportive care facilitates rapid return to function.

Entrapment Neuropathies of the Lower Extremity

Entrapment neuropathies in the lower limbs are a common neurologic problem and may present in any medical setting. Accurate identification and management of these nerve palsies can prevent pain, sensory loss, incoordination, and muscle weakness that may significantly affect a patient's functional mobility. In this article, the authors focus on the cause, signs and symptoms, diagnosis, and treatment of select entrapment neuropathies of the lower extremity, including palsies of the common peroneal, lateral femoral cutaneous, femoral, and posterior tibial nerves.

Macroscopic observations of muscular bundles of accessory iliopsoas muscle as the cause of femoral nerve compression

Compression of the femoral nerve (FN) to the iliac fossa has been reported as a consequence of several pathologies as well as due to the aberrant muscles. The purpose of this research was to investigate the patterns of the accessory muscles of iliopsoas muscles and the relationship of the FN in fifty semi pelvis. Accessory muscular slips from iliacus and psoas, piercing or covering the FN, were found in 19 specimens (7.9%). Based on the macroscopic structure, the muscle was categorized into two types. Pattern 1 as the more frequent variation, was sheet muscular type covering the FN (17 specimens, 89.5%). Pattern 2, the less frequent variation was found on a muscular slip covering the FN (2 specimens, 10.5%). Iliac and psoas muscles and their variants on both types were defined. Appraising the relation between the muscle and the nerves, each disposition of the patterns may be a potential risk for nerve entrapment. The knowledge about the possible variations of the iliopsoas muscle complex and the FN may also give surgeons confidence during pelvic surgery. Recognition of these variations in normal anatomy may be useful to the clinicians when treating patients with refractory leg pain.

Gastrointestinal Mucormycosis After Orthotopic Liver Transplantation Presenting as Femoral Nerve Palsy: A Case Report and Review of the Literature

Mucormycosis has emerged as a major threat to transplant recipients with high morbidity and mortality. This infection most commonly presents with rhino-sino-orbital localization. Gastrointestinal mucormycosis is uncommon, with presenting symptoms usually abdominal in nature. Here, we describe the case of a liver transplant recipient who developed gastrointestinal mucormycosis with an initial manifestation of femoral nerve palsy, ultimately resulting in fungal dissemination and patient demise. This case highlights the challenges in making a timely diagnosis of mucormycosis, particularly in immunocompromised patients.

Femoral nerve palsy after pelvic fracture treated with INFIX: a case series

OBJECTIVE

The treatment of some pelvic injuries has evolved recently to include the use of a subcutaneous anterior pelvic fixator (INFIX). We present 8 cases of femoral nerve palsy in 6 patients after application of an INFIX to highlight this potentially devastating complication to pelvic surgeons using this technique and discuss how it might be avoided in the future.

DESIGN

Retrospective chart review. Case series.

SETTING

Five level 1 and 2 trauma centers, tertiary referral hospitals.

PATIENTS/PARTICIPANTS

Six patients with anterior pelvic ring injury treated with an INFIX who experienced 8 femoral nerve palsies (2 bilateral).

INTERVENTION

Removal of internal fixator, treatment for femoral nerve palsy.

MAIN OUTCOME MEASUREMENTS

Clinical and electromyographic evaluation of patients.

RESULTS

All 6 patients with a total of 8 femoral nerve palsies had their INFIX removed. Variable resolution of the nerve injuries was observed.

CONCLUSIONS

Application of an INFIX for the treatment of pelvic ring injury carries a potentially devastating risk to the femoral nerve(s). Despite early implant removal after detection of nerve injury, some patients had residual quadriceps weakness, disturbance of the thigh's skin sensation, and/or gait disturbance attributable to femoral nerve palsy at the time of early final follow-up.

LEVEL OF EVIDENCE

Therapeutic level IV. See Instructions for Authors for a complete description of levels of evidence.

Perioperative lower extremity peripheral nerve traction injuries

Peripheral nerve traction injuries may occur after surgical care and can involve any of the lower extremity large peripheral nerves. In this review, the authors discuss injuries after knee or hip surgical intervention. The diagnosis, including electrodiagnostic studies, is time sensitive and also relies on a detailed history and physical examination. Successful prevention and treatment involve familiarity with risk and predisposing factors as well as prophylactic measures.

Analysis of lumbar plexopathies and nerve injury after lateral retroperitoneal transpsoas approach: diagnostic standardization

Object

The minimally invasive lateral transpsoas approach has become an increasingly popular means of fusion. The most frequent complication is related to lumbar plexus nerve injuries; these can be diagnosed based on distribution of neurological deficit following the motor and/or sensory nerve injury. However, the literature has failed to provide a clinically relevant description of these complications. With accurate clinical diagnosis, spine practitioners can provide more precise prognostic and management recommendations to include observation, nerve blocks, neurodestructive procedures, medications, or surgical repair strategies. The purpose of this study was to standardize the clinical findings of lumbar plexopathies and nerve injuries associated with minimally invasive lateral retroperitoneal transpsoas lumbar fusion.

Methods

A thorough literature search of the MEDLINE database up to June 2012 was performed to identify studies that reported lumbar plexus and nerve injuries after the minimally invasive lateral retroperitoneal transpsoas approach. Included studies were assessed for described neurological deficits postoperatively. Studies that did attempt to describe nerve-related complications clinically were excluded. A clinically relevant assessment of lumbar plexus nerve injury was derived to standardize early diagnosis and outline prognostic implications.

Results

A total of 18 studies were selected with a total of 2310 patients; 304 patients were reported to have possible plexus-related complications. The incidence of documented nerve and/or root injury and abdominal paresis ranged from 0% to 3.4% and 4.2%, respectively. Motor weakness ranged from 0.7% to 33.6%. Sensory complications ranged from 0% to 75%. A lack of consistency in the descriptions of the lumbar plexopathies and/or nerve injuries as well as a lack of diagnostic paradigms was noted across studies reviewed. Sensory dermal zones were established and a standardized approach was proposed.

Conclusions

There is underreporting of postoperative lumbar plexus nerve injury and a lack of standardization of clinical findings of neural complications related to the minimally invasive lateral retroperitoneal transpsoas approach. The authors provide a diagnostic paradigm that allows for an efficient and accurate classification of postoperative lumbar plexopathies and nerve injuries.

Lumbar Plexopathy Caused by Metastatic Tumor, Which Was Mistaken for Postoperative Femoral Neuropathy

Surgical excision was performed on a 30-years old woman with a painful mass on her left thigh. The pathologic findings on the mass indicated fibromatosis. After the operation, she complained of allodynia and spontaneous pain at the operation site and ipsilateral lower leg. We treated her based on postoperative femoral neuropathy, but symptom was aggravated. We found a large liposarcoma in her left iliopsoas muscle which compressed the lumbar plexus. In conclusion, the cause of pain was lumbar plexopathy related to a mass in the left iliopsoas muscle. Prompt diagnosis of acute neuropathic pain after an operation is important and management must be based on exact causes.