Generally, endoscopic lumbar discectomy is a minimally invasive procedure which, by dispensing with the need for resection of bone and ligament and performing selective evacuation of the intervertebral disc, the incidence of complications is low2,12,13)
and surgery-induced instabilities can be prevented14-19,21)
. In addition, it is less traumatizing, has a shorter operating time, minimal scarring, and conserves the intact intra-epidural lubricant structure, such as epidural fat and yellow ligaments. But, as percutaneous endoscopic discectomy techniques become more popular, the possibility of complications rises accordingly.
Postoperative hematomas following spinal surgery are mostly spinal epidural hematomas. A spinal epidural hematoma is an uncommon complication of spinal surgery10)
. The incidence of postsurgical spinal epidural hematomas that result in neurologic deficits is extremely rare. Lawton et al.11)
reported the incidence rate to be 0.1%. Uribe et al.23)
reported the incidence rate of postsurgical spinal epidural hematomas to be 0.22%, and they also reported the effects of delayed postoperative spinal epidural hematomas, which resulted in clinical deterioration after an asymptomatic postoperative period of about 3 days. There have been no reported cases of psoas muscle hematomas following percutaneous endoscopic operation of lumbar disc herniation in the English medical literature.
In our case reported, the postoperative psoas muscle hematoma following percutaneous endoscopic discectomy might have been caused by the lumbar segmental artery injury.
Generally, angiography is a routine procedure for patients in whom suspicion of arterial injury is high, and the arterial bleeding can be controlled by endovascular embolization. But, in our case, without angiography, a lumbar segmental artery injury was able to be detected by dynamic single-section CT with intravenous contrast media. CT images 15 seconds after the intravenous injection of contrast (arterial phase) showed leakage of contrast media into the psoas muscle hematoma directly, implying active arterial bleeding. On the CT images, the region of active arterial bleeding was the space of the disc in which the material herniated far laterally with the segmental lumbar artery, which was divided into a posterior (vertebral) and an anterior (muscular) branch ().
Schematic view shows the region of active arterial bleeding which is the space of the disc in which material herniated far laterally and in which the segmental lumbar artery is divided into a vertebral and muscular branch.
The lumbar segmental arteries are important parietal branches for the spinal surgeon because of their very close relationship to the vertebral bodies. Because the aorta is situated somewhat to the left of the midline, the right lumbar segmental arteries are longer than those on the left. Both the right and left lumbar segmental arteries dip under the tendinous arch of the psoas muscles situated along the sides of the vertebral bodies. The arteries continue under the psoas muscles until they arrive at the interval between the transverse process of the vertebrae and the medial edge of the quadratus lumborum. While the lumbar segmental arteries course under the psoas muscles, they are accompanied by rami communicantes of the sympathetic chain and the lumbar veins. Anterior to the transverse process, the lumbar segmental arteries are crossed by branches of the lumbar plexus. Like their thoracic intercostal vascular counterparts, the lumbar segmental arteries course to the foramen and divide into a posterior (vertebral) and an anterior (muscular) branch. The anterior (muscular) branch travels forward between the abdominal muscles and terminates by anastomosing with other abdominal wall arteries3,22,24)
. The segmental vessels are identified at the inferior edge of the rostral pedicle, lateral to the existing nerve root20)
. Because of the higher muscular and interseg-mental distribution, the 4th
lumbar arteries are often twice the caliber of the other lumbar arteries. The 4th
lumbar arteries are involved in nutrition of the lower segments by contributions to the iliolumbar vessels. The lateral muscular branch of the 4th
lumbar artery courses superior to the crest of the ilium. This position indicates that it is more likely to be encountered by percutaneous instrumentation. The 4th
lumbar artery provides a relatively large, caudally-directed intersegmental branch that occurs near the level of the intervertebral foramen1)
Fortunately, in the case reported herein, the active arterial bleeding causing the psoas muscle hematoma was controlled spontaneously without any procedures, such as embolization or reoperation. If the arterial bleeding had continued, an angiography would have been performed and embolization may have been required. Under only conservative treatment, the unstable vital signs recovered to normal and the patient's pain improved.
It is unclear how the arterial injury occurred. There was no significant bleeding during the endoscopic discectomy, and the level of injury, as seen on CT images, appeared to be at the insertion site for the endoscope. It is doubtful that the working sheath approach to the disc space made at the level of the vertebra might have caused the vascular injury. The space of the disc in which material herniated far laterally is closely connected with the running lumbar segmental artery, making it highly likely that the segmental artery injury occurred while inserting the endoscope ().
Fig. 4 3D reconstruction computed tomography image shows the space of the disc in which the material herniated far laterally is closely connected with the running lumbar segmental artery; it is likely that injury of the segmental artery occurred during insertion (more ...)
The purpose of this case report was to present a case of an injury to a branch of the L4 segmental lumbar artery following percutaneous endoscopic lumbar discectomy and to give a warning to the surgeons of possibility of arterial injuries during percutaneous endoscopic lumbar discectomy.