Vertebral artery injury in C1-2 transarticular screw fixation: results of a survey of the AANS/CNS Section on Disorders of the Spine and Peripheral Nerves

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The 847 active members of the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Section on Disorders of the Spine and Peripheral Nerves were surveyed to quantitate the risk of vertebral artery (VA) injury during C1-2 transarticular screw placement.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>This retrospective study elicited the number of patients treated with transarticular screws, the number of screws placed, the incidence of VA injury and subsequent neurological deficit, and the management of known or suspected VA injury.</jats:p> <jats:p>Two hundred thirteen (25.1%) of the 847 surgeons responded. One hundred one respondents (47.4%) had placed a total of 2492 C1-2 transarticular screws in 1318 patients. Thirty-one patients (2.4%) had known VA injuries and an additional 23 patients (1.7%) were suspected of having injuries. However, only two (3.7%) of the 54 patients with known or suspected VA injuries exhibited subsequent neurological deficits and only one (1.9%) died from bilateral VA injury. Other iatrogenic complications included dural tears, screw fractures, screw breakout, fusion failure, infection, and suboccipital numbness.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Including both known and suspected cases, the risk of VA injury was 4.1% per patient or 2.2% per screw inserted. The risk of neurological deficit from VA injury was 0.2% per patient or 0.1% per screw, and the mortality rate was 0.1%. The choice of management of intraoperative VA injuries was evenly divided between placing the patient under observation and initiating immediate postoperative angiography with possible balloon occlusion.</jats:p></jats:sec>

Anatomical evaluation of the groove for the vertebral artery in the axis vertebrae for atlanto-axial transarticular screw fixation technique

“…In these pathological conditions, various surgical applications are used for fixation and fusion of the atlanto-axial complex, including posterior, posterolateral and/or anterior approaches (Wilke et al, 1992;Marcotte et al, 1993;Coyne et al, 1995). Among these approaches, the atlanto-axial transarticular screw fixation technique has the advantage of increased biomechanical stability and allows the least rotation (Paramore et al, 1996;Wright and Lauryssen, 1998;Dickman and Sonntag, 1998). Also, biomechanical studies on cadaveric spines have shown this technique to provide significantly more stability in axial rotation than other posterior fusion techniques and to prove equally stable in flexion, extension, and lateral bending (Hanson et al, 1991;Wilke et al, 1992).…”

“…At the present time, this technique for atlanto-axial instability has become increasingly popular. However, transarticular screw fixation of the atlanto-axial complex has been said to be a dangerous and technically difficult procedure because it carries the risk of screw malpositioning and neural and vascular injury (Coric et al, 1996;Paramore et al, 1996;Abou Madawi et al, 1997b;Wright and Lauryssen, 1998). For these reasons, we have directed an anatomical study on dry human vertebrae to determine the optimum screw trajectory and its safety margin.…”

“…Abou Madawi et al (1997b) reported five (8.1%) patients who sustained intraoperative vertebral artery injury. Wright and Lauryssen (1998) reported that the total risk for vertebral artery injury was 2.2% per screw placed, or 4.1% per patient treated with Ͼ1,300 patients in the AANS/CNS survey. Lately, Dickman and Sonntag (1998) reported that of 226 screws placed, 221 (98%) were positioned satisfactorily and five screws (2%) were malpositioned without clinical symptoms, and only one screw occluded the vertebral artery in the vertebral angiography.…”

“…The atlanto-axial transarticular screw fixation technique for atlanto-axial instability has become increasingly popular because of its greater biomechanical stability and superior fixation of atlanto-axial rotation (Hanson et al, 1991;Wilke et al, 1992;Stillerman and Wilson, 1993;Wright and Lauryssen, 1998). Nevertheless, the anatomy of this region makes proper installation of these screws technically challenging.…”

Isocentric C-arm three-dimensional navigation versus conventional C-arm assisted C1–C2 transarticular screw fixation for atlantoaxial instability

“…Fusion was defined by a lack of motion on flexion-extension plain radiographs and bridging trabecular bone between the graft and C1-C2 on CT scans [17]. Screw position of the screws was divided into three grades: grade 0 (ideal placement): screw completely within the bone cortex; grade 1 (acceptable placement): less than 50 % of the diameter of the screw enters the surrounding cortex and less than 5 mm protrudes from the anterior cortex for transarticular screws; grade 2 (unacceptable placement): clear violation of transverse foramen or spinal canal, regardless of clinical neurovascular complications [18].…”