Lymphocele, defined as a collection of lymphatic fluid encased by thin fibrous walls [1], is a known complication following pelvic surgery, with an incidence rate between 25% and 61% [2]. While it is typically asymptomatic, symptoms can manifest in about 3% to 6% of patients, leading to a range of complications [1]. A limited number of reports have described lower extremity weakness resulting from compressive neuropathy after pelvic surgery.

Previous studies have reported that the incidence of neuropathy following gynecological pelvic surgery ranges from 1.9% to 3.2% [3,4]. Lower extremity weakness after prolonged pelvic surgery is often caused by neuropathy, primarily due to sustained nerve compression. This compression can result from incorrect patient positioning or the prolonged or inappropriate use of surgical retractors, and it can meaningfully affect patient functioning and quality of life by causing lower limb impairment [4]. Additionally, neuropathy may arise from other causes, such as intraoperative nerve damage or hematoma.

This report details the case of a patient who developed obturator neuropathy caused by pelvic lymphocele following laparoscopic staging surgery for ovarian cancer. This condition was diagnosed with an electrodiagnostic examination.

A 52-year-old woman was referred to the Department of Rehabilitation Medicine due to weakness in her left leg and gait disturbance that had persisted for 2 weeks following pelvic surgery. She had been diagnosed with ovarian cancer and had undergone staging laparoscopy, which included total laparoscopic hysterectomy, bilateral salpingo-oophorectomy, pelvic lymph node dissection, and omentectomy. Four days after surgery, she began experiencing difficulty lifting her left leg, inguinal stiffness, and discomfort when walking.

Physical examination revealed muscle strength of Medical Research Council (MRC) grade 2 in the left hip flexor and adductor muscles and grade 3 in the knee extensor muscles. All muscles of the right lower limb were normal. The patient also reported hypoesthesia in the left medial thigh. Deep tendon reflexes, including knee and ankle jerks, were normoactive.

Needle electromyography (EMG) (Table 1) and nerve conduction studies (NCS) (Table 2) were performed 2 weeks after the onset of symptoms. NCS of the femoral nerve displayed a typical response. However, EMG of the left adductor longus muscle demonstrated abnormal spontaneous activity and decreased voluntary recruitment of motor unit action potentials (MUAPs), indicative of left obturator neuropathy.

In addition to electrodiagnostic examination, the patient underwent pelvic magnetic resonance imaging (MRI) (Fig. 1). This imaging revealed a lobulated cystic lesion of approximately 3.2 × 3.2 × 4.2 cm at the left pelvic wall, suggestive of lymphocele. The potential for associated obturator nerve injury could not be excluded. Instead of opting for drainage, conservative treatment (including rehabilitation therapy) was considered for the patient, given the possibility of spontaneous absorption.

Thus, we conducted a comprehensive rehabilitation therapy program that included hip range-of-motion exercises, progressive resistance exercises, gait training, and neuromuscular electrical stimulation.

Electrodiagnostic evaluation, performed 3 months later (Tables 3, 4), revealed an improvement in the MRC scale from 2 to 4. Increased recruitment of MUAPs was confirmed on needle EMG examination. Four months later, improvements were noted on abdominopelvic computed tomography (CT) (Fig. 2). Although complete recovery had not been achieved, the improving trend led us to continue conservative treatment, including rehabilitation therapy, while monitoring progress.

Written informed consent was obtained from the patient. This study was approved by the Institutional Review Board of Konyang University Hospital Hospital (IRB no: 2023-02-020-001).

One notable complication of pelvic surgery is the formation of lymphoceles, which are collections of lymphatic fluid surrounded by thin fibrous walls. Pelvic lymphoceles can develop after surgery when lymphatic vessels are damaged due to truncation or improper ligation [1]. The incidence of symptomatic lymphocele (3% to 6%) is lower than that of the asymptomatic condition (13% to 20%). Symptoms primarily result from pressure on adjacent anatomical structures, leading to pain, swelling, numbness, or deep venous thrombosis [1]. Treatment is indicated based on the size or symptoms of lymphocele, and various methods have been described, including needle aspiration, percutaneous catheter drainage with or without sclerotherapy, and surgical drainage [5]. In a previous study, conservative management, including mechanical compression and a low-fat diet, was shown to be effective against swelling [6]. Consequently, we employed simple physical therapy and range-of-motion exercises to increase lymphatic flow, reduce swelling, and improve MRC grade.

The obturator nerve arises from the anterior division of the L2, L3, and L4 spinal nerve roots. It descends within the psoas major muscle, emerges from its medial border, and runs along the lateral wall of the lesser pelvis. The nerve then enters the thigh via the obturator canal, where its anterior branch innervates the muscles of the medial thigh. Obturator mononeuropathy can lead to adductor weakness and cutaneous sensory deficits in the medial thigh [7].

This report presents a case of obturator mononeuropathy caused by lymphocele formation after pelvic surgery. According to prior research, neuropathy following pelvic surgery occurs in about 1.9% to 3.2% of cases [3,4]. Obturator mononeuropathy is relatively rare due to the nerve’s protected location within the pelvis and medial thigh [8]. Previous studies have estimated the incidence of neuropathy after pelvic surgery to be around 2%, with the primary causes being improper patient positioning and retractor usage. Other nerves frequently affected in such cases include the ilioinguinal/iliohypogastric nerve, genitofemoral nerve, femoral nerve, and lumbosacral nerve plexus [9].

We diagnosed obturator mononeuropathy using electrodiagnostic evaluation. To differentiate it from conditions such as peripheral neuropathy or lumbar plexopathy, we performed needle EMG on the adductor muscle groups. The obturator nerve descends through the fibers of the psoas major, complicating nerve conduction testing. For an accurate diagnosis of obturator nerve injury, it is necessary to examine both the adductor magnus muscle, which is innervated by the posterior branch, and one of the muscles innervated by the anterior branch—either the adductor longus, brevis, or gracilis. However, one limitation of this case was that only the adductor longus muscle was examined. The test results strongly suggested axonotmesis of the obturator nerve, which was consistent with the symptoms exhibited by the patient.

The prognosis for acute onset compressive neuropathy is generally favorable, according to a limited number of studies. A case series suggested that most patients with acute onset recovered well following conservative treatment, regardless of cause or the severity of EMG findings [8]. For asymptomatic lymphocele, spontaneous regression is commonly observed, and the condition can be monitored over time; however, this process may take several months [10]. In the case presented here, the patient did not achieve full recovery despite conservative management of symptomatic lymphocele, even though follow-up pelvic CT indicated that the lymphocele had resolved. This raises the question of whether early intervention or aspiration surgery might have led to complete recovery. Additionally, determining the optimal timing for invasive intervention, based on the condition’s progression over time, could improve the prognosis in future cases.

Postoperative nerve compression syndrome has various causes, including hematoma and direct nerve injury. In the present case, imaging and NCS identified lymphocele as the cause of compression neuropathy. Lymphocele is a condition commonly discussed in the contexts of cancer and lymphatic rehabilitation, but it is relatively rare in the field of physical medicine and rehabilitation. Although most cases are asymptomatic and managed conservatively, persistent symptoms may necessitate interventions such as percutaneous catheter drainage or surgical removal, with success rates of 79% to 82% in previous research [10]. This case report describes a patient with obturator nerve entrapment syndrome caused by lymphocele, who demonstrated functional improvement through conservative management and rehabilitation. The report also includes a review of the literature on lymphocele.

In conclusion, our findings emphasize the importance of considering lymphocele in patients who present with lower limb weakness following pelvic surgery. Various evaluations, including electrodiagnostic testing and MRI, should be combined to obtain an accurate diagnosis and establish an appropriate rehabilitation plan that facilitates a successful return to daily activities.