Iatrogenic vertebral artery injury

Vertebral artery arteriovenous fistula (AVF), after iatrogenic vertebral artery injury (VAI), is a serious complication of upper cervical spine fixation surgery.

Since the cervical lateral mass screw fixation technique has been well established, the concern of vertebral artery injury is higher than ever before ¹⁾.

Posterior fusion of the atlas and axis by transarticular screw fixation or Magerl screws pose an additional risk of Iatrogenic vertebral artery injury, neurological deficit or inadequate bony purchase.

Vertebral artery injury is one of the most dangerous complications of screw fixation and is usually due to incorrect cervical pedicle screw entry with vertebral artery injury. The incidence of iatrogenic vertebral artery injury is 1.3%–4% for Magerl fixation ²⁾. Fortunately, the risk of neurological deficit is low (0.2%) ³⁾. Mortality is greatly increased if both vertebral arteries are injured. Lateral deviation of screws can often lead to penetration of the foramen transversalis and subsequent vertebral artery injury ⁴⁾. Current trends include the use of intraoperative CT and computer-assisted navigation systems to improve screw trajectory and reduce screw perforation ^{5) 6)}.

Although vertebral artery injury (V2) may occur during an anterior cervical approach, (uncoforaminotomy), the frequency of vertebral artery injury is actually low ^{7) 8)}.

Qian et al., report a case of a 59-year-old female patient who had a vertebral AVF following transpedicular occipitocervical fixation surgery. Endovascular embolization of the AVF was successfully performed using ethylene vinyl alcohol. From this case they learned that preoperative evaluation of the course of the vertebral artery is necessary, and vertebral artery embolism is an effective and safe method to treat vertebral AVF after proof of a patent second vertebral artery ⁹⁾.

In standard anterior cervical discectomy, complete resection of the uncinate process is not commonly attempted because of the risk of injury to the vertebral artery. This may result in incomplete decompression of the nerve root when there is severe osseous cervical foraminal stenosis.

Iatrogenic vertebral artery injury (VAI) is a rare but significant complication of anterior cervical spine surgery. In the grossly degenerate cervical spine the VA may adopt a tortuous pathway thus predisposing to inadvertent injury during surgery ¹⁰⁾.

In a high-volume surgical center, the incidence of VAI during low-risk cervical spine surgery is extremely low, comprising 0.3 % of all cases. The major risks are delayed sequels of the vessel wall laceration. In cases of VAI, immediate angiographic diagnostics and generous indications for endovascular treatment are obligatory ¹¹⁾.