Vascular injury after lumbar disc surgery : case report and review of the literature

A 56-year-old woman was scheduled for a one-day L5-S1 microdiscectomy. Her ASA physical status was 2, because she suffered from an ectodermal dysplasia and a chronic sinusitis. She had already undergone a few operations, including appendicectomy, sectio and surgical repair of palatoschisis during childhood. She also had a L4-L5 lumbar discectomy 20 years ago. She had an esophageal stenosis due to previous traumatic intubation, and this stenosis have been managed through balloon dilatation. Her current medications included only risendronate (bisphosphonate). The anesthesia was induced using 180 mg of propofol, 10 µg of sufentanil and 20 mg of mivacurium in order to facilitate endotracheal intubation. Intubation was uneventful. The patient was positioned prone , with hip and knee at 90° of flexion. Rapidly after positioning, blood pressure fell from 130/85 mmHg to 90/45. During surgery, the need for vasoactive medications was moderate, with only two 5 mg boluses of ephedrine, in order to maintain the systolic blood pressure above 80 mmHg. Surgery went well, with no reported intraoperative complications (i.e. no excessive bleeding). Analgesia was initiated intraoperatively using 1 g of paracetamol, 30 mg of ketorolac and 4 mg of piritramide by the end of the surgery. In the recovery room, the patient exhibited tachycardia, with a heart rate of 125 beats per minute and had a low blood pressure (68/35 mmHg) that motivated the use of phenylephrine boluses. Volume expansion was initiated using hydroxyethyl starch, namely 500 ml of Voluven ®, but hypotension persisted. After consultation with the neurosurgeon in charge, a CT-scan was scheduled in order to exclude retroperitoneal bleeding. The patient received another peripheral access, an arterial line and a central venous catheter in order to permit an infusion of noradrenaline. Unfortunately, due to persistent hemodynamic instability and despite aggressive fluid management and transfusion (2 units of erythrocytes and 4 units of fresh frozen plasma), the patient was immediately readmitted to the operating theater where a lombotomy was performed. A double perforation of the left common iliac artery was discovered and repaired with a patch. Thereafter, the hemodynamic situation improved and the remaining perioperative care was uneventful, except for a right pneumothorax (secondary to pleural burglary while attempting to place a central venous catheter in the right subclavian vein).This pneumothorax was drained. A CT scanner control at postoperative day 2 showed a retroperitoneal hematoma, with no more signs of active bleeding. The patient left the hospital at postoperative day 11, with no other complications.

Discussion

The first description of vascular complication during lumbar spinal surgery was in 1945 [1].

The incidence of such a complication seems to be low, ranging from 0.039% to 0.14% [2], but could be higher since some cases remain undetected and/or not reported in the literature [3,4]. Interestingly, despite improvements in surgical techniques (such as microscopic and laser-assisted surgery), there has been no decrease in the incidence since 1945 [3]. Nevertheless, when such a complication occurs, the mortality rate is high (15-100%), and the delay between the injury and the treatment directly affects the mortality rate [3]. When arterial injuries are concerned, the mortality rate approaches 100% when surgery is not performed immediately [5].

ANATOMY

Due to the anatomy of the prevertebral space, a high number of vessels can be involved, depending on the level of surgery [6]. The most common involved vessel is the left common iliac artery, followed by the left common iliac vein [7], because they are located immediately anterior to the L4-L5 intervertebral space. Other structures may also be compromised, including viscera and ureters [8].

The supine position of the patient plays a role, inducing pressure on the thoracoabdominal regions, which compresses the great vessels against the vertebral body and makes them more likely to be injured [9]. The disc degeneration may weaken the anterior longitudinal ligament and alter the relationship between the ligament and the adjacent vascular structures [3]. A medical history of abdominal surgery, a previous disc surgery or the inexperience of the surgeon are also risk factors of vascular injuries during lumbar surgery [5].

SYMPTOMS

The symptoms depend on the type of injured vessel. A severe arterial damage almost always causes an acute life threatening retroperitoneal hemorrhage, with refractory hypotension and severe tachycardia. Patients can develop abdominal distention and pain, nausea and vomiting, dizziness, pallor or coldness of the extremities. A progressive drop in arterial blood pressure due to hypovolemia, a wide pulse pressure, tachycardia, a hematocrit drop, and a decrease in skin temperature should alert the physician about potential bleeding and motivate an immediate exploration [5]. Noteworthy, even in case of large retroperitoneal hemorrhage, bleeding from the wound or in the surgical field during surgery is not present in more than 50% of cases. This can be explained by the self-sealing effect of the anterior annulus fibrosus and anterior longitudinal ligament. Hence, blood pooling in the disc space may often not be apparent in the surgical field [3, 5].

In case of venous injury alone, bleeding is generally self-limited, and even large venous lacerations do not usually require surgical treatment. The clinical symptoms of such an injury can be pain and swelling in the legs, caused by thrombosis of pelvic veins [5]. Furthermore, prone position during surgery may confer a degree of vascular compression which may temporarily dab vascular tears [3].

Finally, if an artery and a vein are simultaneously injured, arteriovenous fistula can develop. In this case, bleeding can be reduced to some extent [9]. Signs and symptoms can show up afterwards, including swelling of the legs, fatigue, shortness of breath, cardiac failure, machinery bruit in the abdomen or delayed bleeding [3].

DIAGNOSIS AND TREATMENT

Any patient with intraoperative recognized vessel injury and/or signs of life-threatening hypovolemic shock should be managed with vigorous volume replacement and urgent vascular repair. Of note, upon discovery of the vascular injury, there is no time for further investigation, as the mortality rate increases with the delay before the surgery. If the patient is hemodynamically stable, abdominal ultrasonography or CT angiography are the preferred diagnosis methods to confirm vessel injury and retroperitoneal hematoma [3].

Multitude treatments are possible, including ligation of arteries and veins, closure of fistulas, arterial bypass and patch plasty, stent graft placement, coil embolization, balloon occlusion and glue injection [9]. Historically, the treatment was based on direct surgical repair of injured vessels, but this may result in considerable blood loss and complications. Nevertheless, in case of acute onset and rapid deterioration leading to hypovolemic shock, open surgery should be performed immediately, with no time spent on diagnostic procedures [3, 5]. Contrarily, if the clinical state of the patient allows it, endovascular techniques have been proven to be a good alternative. The advantages are an absence or a minimal abdominal incision, minimal blood loss and reduced length and depth of anesthesia. Endovascular therapy is well tolerated by patients, and can be performed under local anesthesia [4]. It results in shorter hospitalizations periods when compared with classic surgical repair. However, this is dependent on the availability of tertiary vascular services [8].

CONCLUSION

Vascular lesions are a well-known complication of lumbar disc surgery, although rare. The mortality rate varies from 15 to 65%, depending on the implied vessel and rapidity of diagnosis and treatment. The symptoms also depend on the type of injured vessel. If signs of hypovolemic shock (tachycardia, hypotension, wide pulse pressure, dizziness, pallor, cold extremities) are discovered in a patient after lumbar disc surgery, a vascular lesion must be suspected. Such a situation requires aggressive management, including immediate surgery. If the patient is stable, abdominal echography or CT angiography are first choice investigation procedures. Endovascular therapies are a good option in stable patients, but may not be widely available.

BIBLIOGRAPHY

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