Diagnosis and management of a giant retroperitoneal hematoma compressing the femoral nerve, following an ultrasound-guided lumbar sympathetic block: a case report

Abstract

Background

The lumbar sympathetic nerve block stands as a pivotal approach in managing complex regional pain syndrome (CRPS) in the lower limbs. Retroperitoneal hemorrhage is an extremely rare and severe complication of lumbar sympathetic nerve block. Here, we report for the first time a case of retroperitoneal hemorrhage that initially presented with symptoms of femoral nerve compression.

Case presentation

An 81-year-old elderly female was diagnosed with CRPS. After undergoing an ultrasound-guided lumbar sympathetic nerve block at our hospital, discomfort in her right lower back was experienced, followed by stabbing pain, numbness in the anterior thigh, and significant lower limb movement impairment. We considered that the femoral nerve might be compressed by a hematoma or abscess. An emergency percutaneous drainage was performed, resulting in partial symptom relief. However, two days later, signs of hemorrhagic shock were observed in the patient. An emergency lumbar arterial embolization was performed, effectively stabilizing her vital signs. One week later, lower limb pain and numbness disappeared, and right lower limb motor function fully recovered.

Conclusions

When retroperitoneal hemorrhage is suspected, prompt computed tomography (CT) or bedside ultrasound should be conducted. Once imaging supports the diagnosis, immediate digital subtraction angiography (DSA) could be utilized to identify the bleeding source and conduct embolization.

Background

The lumbar sympathetic nerve block is widely used to treat ischemic diseases of the lower limbs and vascular spasms [1]. This technique involves injecting local anesthetics into the sympathetic trunk, which could reduce pain and improves blood circulation. Although rare, retroperitoneal hemorrhage is an extremely serious complication associated with lumbar sympathetic nerve block. Low back pain, hypotension, and shock are the most common clinical symptoms of retroperitoneal hemorrhage, posing a significant threat to the patient’s life. Here, we report a rare case of retroperitoneal hemorrhage initially presenting with neurological symptoms.

Case presentation

An 81-year-old female patient presented to our department with swelling and discomfort in her right foot, along with limited mobility. Six months prior, she underwent arterial stent implantation and balloon angioplasty in her right lower limb at another hospital to address peripheral arterial occlusive disease. One month after the procedure, she started experiencing exacerbated symptoms in her right foot: skin swelling, redness, burning sensation, numbness, tenderness, and restricted movement. She has a medical history of peripheral arterial occlusive disease, coronary artery disease and polycythemia vera, and has been on long-term anticoagulation therapy with rivaroxaban and treatment with Anagrelide for polycythemia vera.

On the first day of admission, we found that her right foot was swollen, red, had an elevated skin temperature, significant tenderness, and limited mobility, with an NRS score ranging from 4 to 7 [2]. CRPS was considered based on the patient’s symptoms and signs. Coagulation function tests showed normal results: prothrombin time (PT) of 15s, activated partial thromboplastin time (APTT) of 17s, and fibrinogen level of 4.23 g/L. Rivaroxaban was discontinued and replaced with low molecular weight heparin. Blood tests revealed RBC 5.8 × 10¹²/L, which was above normal levels. The day after admission, following the exclusion of contraindications, she received ultrasound-guided right lumbar sympathetic nerve block treatment.

The patient was positioned on their left side, with non-invasive blood pressure, pulse oximetry, and electrocardiogram monitoring. Under ultrasound guidance, the right side of the spine was located at the level of the L2 transverse process, displaying the characteristic “shamrock sign,” where the stalk represents the transverse process, the upper part represents the quadratus lumborum muscle, the dorsal part represents the erector spinae muscle, and the ventral part represents the psoas major muscle. The probe was slightly moved towards the head until the transverse process just disappeared. The needle was inserted in-plane under ultrasound guidance, passing through the lateral side of the psoas major muscle to the anterolateral side of the L2 vertebral body and posterior to the inferior vena cava, where the medication (0.3% Lidocaine 15 ml + Mecobalamin 0.5 mg) was injected. This was visualized as a local hypoechoic fluid surrounding and spreading along the anterolateral side of the vertebral body. The fourth day after admission, after three treatments, there was partial improvement in her pain and swelling compared to before treatment. However, the tenth day after admission, after six treatments, she experienced discomfort in the right lumbar region, stabbing pain in the anterior thigh, numbness, difficulty in hip flexion, and restricted lower limb movement. Blood tests revealed WBC 28.83 × 10⁹/L, neutrophils 25.8 × 10⁹/L, and RBC 5.5 × 10¹²/L. A suspicion arose that the femoral nerve could be compressed by a hematoma or abscess. The CT scan revealed a mixed high-density shadow in the right retroperitoneum (Fig. 1A). Emergency CT-guided retroperitoneal hematoma puncture and drainage surgery was performed (Fig. 1B). Approximately 110 mL of dark red fluid was drained within 24 h, resulting in partial improvement of her symptoms. However, on the fourteenth day after admission, she developed lower abdominal pain, chest tightness, and dyspnea. Blood pressure ranged from 110–140/65–77 mmHg, and heart rate was 108–128 beats/min. Her RBC count decreased from 5.8 before admission to 2.75*10^12/L, hemoglobin (Hb) decreased from 134 to 65 g/L, and pro-BNP was 2870 pg/mL. We considered hemorrhagic shock combined with heart failure. Immediate transfusion and intravenous nitroglycerin were administered to stabilize her vital signs. The fifteenth day after admission, after stabilizing the patient’s condition, right L2 segment arterial embolization was performed under DSA (Fig. 2). Post-operatively, her vital signs stabilized. The twenty-third day after admission, her lumbar and abdominal discomfort and numbness in the anterior thigh completely resolved. Her right lower limb mobility and hip flexion function returned to normal. Follow-up at two months confirmed complete absorption of her retroperitoneal hematoma.

Fig. 1

Computed tomographic image of the axial section of the abdomen. (A) Mixed high-density shadows can be seen in the right retroperitoneal space (7.8*8.8*17.8 cm), with the right kidney being pushed forward and upward. (B) After the puncture and drainage of a hematoma in the right psoas major muscle, a drainage tube shadow is observed in the surgical area

Fig. 2

Angiography showing (A) active extravasation of the contrast agent from the second lumbar segmental artery. (B) After embolization, the extravasation of the contrast agent ceased

Discussion and conclusions

CRPS is characterized by pain, swelling, restricted mobility, vasomotor dysfunction, skin changes, and other autonomic dysfunctions. CRPS is often associated with autonomic nervous dysfunction; consequently, sympathetic nerve blockade has emerged as a primary treatment for the condition. Sympathetic nerve blockade is effective in alleviating pain and facilitating physical therapy and rehabilitation. Furthermore, sympathetic nerve blockade offers diagnostic guidance for CRPS. A favorable response to the block supports the diagnosis and helps guide subsequent treatment strategies. Ultrasound-guided sympathetic nerve blockade has shown promise as a treatment for CRPS [3]. Ultrasound-guided nerve block provides real-time imaging and allows for immediate intervention. Compared to X-rays and CT scans, ultrasound-guided nerve block reduces radiation exposure for both clinicians and patients. However, due to attenuation of ultrasound waves, imaging of deeper tissues remains less effective. Retroperitoneal hematoma is an extremely rare complication associated with lumbar sympathetic nerve blockade [4]. Major risk factors for this complication include advanced age and anticoagulant use. The patient had been taking rivaroxaban, a novel oral anticoagulant that prevents thrombin generation by inhibiting factor Xa, used for thromboprophylaxis and treatment. A large prospective study involving 11,221 participants across 47 countries demonstrated lower rates of bleeding and stroke in atrial fibrillation patients treated with rivaroxaban [5]. Conversely, a case report indicated that apixaban, a drug similar to rivaroxaban, may cause spontaneous retroperitoneal hemorrhage in elderly atrial fibrillation patients [6]. Given the patient’s history of right lower limb arterial stenting and coronary artery disease, rivaroxaban was discontinued upon admission and replaced with low molecular weight heparin, with an evaluation of her coagulation function. Notably, the patient also had polycythemia vera. Bleeding is a common complication among patients with primary thrombocytosis and polycythemia vera [7]. Anagrelide, though known to cause heart failure, severe arrhythmias, and headaches, can also lead to gastrointestinal symptoms and bleeding [8, 9]. Therefore, the patient’s condition, medication factors, and multiple blockade treatments may increase her bleeding risk. For high-risk patients like this one, selecting puncture points to minimize bleeding risk is crucial. The lumbar sympathetic nerve originates from the thoracic sympathetic nerve, extending along the anterior and lateral aspects of the lumbar vertebrae, with 4 to 5 lumbar sympathetic ganglia. It primarily regulates vascular tone and sweat gland secretion in the lower limbs. Importantly, the lumbar segmental artery and lumbar sympathetic chain intersect at the lower third of the vertebral body [10, 11]. Therefore, puncturing above the upper margin of the vertebral arch or the middle-upper two-thirds of the vertebral body is considered relatively safe for blockade. In summary, for such patients, the risks and benefits of discontinuing or replacing anticoagulant medications should be thoroughly assessed before intervention. If lumbar sympathetic nerve blockade proves effective, direct destruction of the sympathetic chain may be considered to reduce damage from repeated punctures. Additionally, selecting puncture points at the middle-upper two-thirds of the vertebral body could avoid the segmental lumbar vessels and reduce bleeding risk.

Common clinical symptoms of retroperitoneal hematoma include low back pain. Hematomas compressing nerves and visceral organs can lead to neuropathic pain, gastrointestinal, and urinary system dysfunction. If not treated promptly, patients with extensive bleeding may develop Grey Turner’s sign, hypotension, or even shock. Here, we found a case of retroperitoneal hemorrhage that initially presented with symptoms of femoral nerve compression. The patient initially presented with anterior thigh pain, numbness, lower limb movement disorders, and weakness in hip flexion. Due to the patient’s concurrent polycythemia vera, early RBC and Hb levels were not significantly reduced, which could affect clinical diagnosis. Studies have shown that conservative treatment is preferred for retroperitoneal hematoma patients receiving anticoagulant therapy [12]. Another case report suggested that direct embolization therapy can more effectively control bleeding in patients with retroperitoneal hematoma following lumbar sympathetic nerve blockade [4]. In summary, reflecting on the management experience of this case, the initial drainage only partially alleviated the patient’s symptoms. However, continuous bleeding resulted in a worsening of the patient’s condition. Therefore, we recommended that early CT or bedside ultrasound should be performed when retroperitoneal hemorrhage is suspected. Once auxiliary examinations confirm retroperitoneal hematoma, prompt DSA should be performed for direct vascular imaging, actively identifying bleeding points and performing embolization to reduce the risk of continued bleeding.

In conclusion, retroperitoneal hematoma following lumbar sympathetic nerve blockade is an extremely rare complication, and many clinicians lack relevant clinical diagnostic and treatment experience. The key to management lies in early symptom recognition, rapid CT and bedside ultrasound diagnosis, and actively identifying and embolizing bleeding points. Additionally, for patients at high risk of bleeding, a comprehensive assessment of anticoagulant use should be conducted. Selecting puncture points at the upper two-thirds of the vertebral body and minimizing the frequency of punctures could effectively further reduce the risk of bleeding in patients.