Original ArticleModified Posterior C1 Lateral Mass Screw Insertion for Type II Odontoid Process Fractures Using Intraoperative Computed Tomography–Based Spinal Navigation to Minimize Postoperative Occipital Neuralgia
Introduction
Odontoid fractures occur in up to 15% of all cervical spine injuries.1 Of these, odontoid process type II fractures make up 40%–82%.2 Various techniques have been described for posterior instrumented C1-2 fusion in cases of instability,3, 4, 5, 6, 7, 8 the 2 most commonly used being transarticular screw fixation as described by Jeanneret and Magerl7 and posterior polyaxial screw-rod construct with C1 lateral mass and C2 pedicle screws popularized by Harms and Melcher in 2001.3 The transarticular Jeanneret and Magerl technique has become less prominent over time because it has several limitations: factors such as a high-riding vertebral artery, disadvantageous bony anatomy, obesity, and sagittal alignment of the cervical and/or thoracic spine render the technique unfeasible for 26% of patients.9 The Goel-Harms technique, which evades these limitations, has become popular among surgeons worldwide.3, 10, 11, 12, 13, 14 Although Harms and Melcher did not encounter any neurovascular complications in their series of 37 patients, increasing numbers of surgeons using their technique have subsequently reported severe complications during preparation of the classic C1 lateral mass entry point, such as bleeding from the epidural venous plexus, which can obscure visualization, complicate screw placement, and force surgery to be abandoned in the worst cases.15, 16, 17 Occipital neuralgia, described in up to 35% of cases,18 is a complication associated with significant postoperative patient morbidity and is not to be underestimated.10, 17 A probable cause is irritation of the C2 dorsal root ganglion as a result of intraoperative manipulation, caudal traction, and reduction of C1 on to C2 when the C1 lateral mass entry point is exposed.19 Once intractable occipital neuralgia develops and cannot be managed medically or with nerve blocks, further surgery such as ganglionectomy, rhizolysis, or C2 nerve root decompression is required.20
To avoid this complication, several authors recommend bilateral sectioning of the C2 nerve roots to allow the C1 entry point to be adequately exposed, to more easily control bleeding from the vertebral venous plexus, and to reduce the incidence of postoperative occipital neuralgia.16, 21, 22 However, sectioning of the C2 nerve roots remains controversial, and little is known about the outcome for patients.23 Postoperative occipital numbness in the territory of the greater occipital nerve can be a major problem, causing significant discomfort and limitations in daily activities.24
In an attempt to reduce or obviate neurovascular complications, we introduce a modified Goel-Harms technique using spinal navigation based on intraoperative computer tomography (CT) with a high C1 entry point at the junction of the posterior arch and the superior-posterior part of the C1 lateral mass. The aim of this study was to assess the safety and feasibility of this technique regarding the development of occipital neuralgia and neurovascular complications, including excessive bleeding from the venous plexus and vertebral artery injury.
Section snippets
Patient Demographics and Preoperative Diagnosis
With the approval of the local ethics committee, 63 consecutive patients who had suffered an acute traumatic odontoid type II fracture and had undergone posterior cervical fusion with our modified C1 lateral mass technique between January 2007 and July 2015 were investigated retrospectively. All patients had signed a patient consent on admission. Based on the local ethics committee guidelines, no further consent was required for this retrospective study. Regardless of age, sex, osteoporosis,
Patient Population
Of the 63 patients who met the inclusion criteria, 35 were men (55%) and 28 were women (45%), with a median age of 70 years (range, 19–96 years) at the time of surgery (Table 2). Mean body mass index was 29 kg/m2, indicating overweight status. The 6-month follow-up was regarded as the primary end point.
Perioperative/Clinical Outcome
There was no excessive bleeding from the venous plexus during any surgery. In 1 case, transfusion of blood products was necessary because of a coagulation disorder, which was diagnosed
Discussion
The Goel-Harms technique offers several advantages over other stabilization techniques but can be technically demanding even for experienced surgeons.25, 26 It comprises 2 procedures that have downsides: to determine the correct C1 lateral mass entry point, the C1-2 joint has to be exposed laterally and prepared fully to the required depth, which can cause excessive epidural bleeding from the vertebral venous plexus (Figure 6A); and the typically large C2 nerve root must be distracted downward
Conclusions
When surgical techniques are altered, it is of the utmost importance to assess patient safety and the complication and revision rates. The data from this study show that modifying the entry point of the C1 lateral mass screw to the junction of the C1 posterior arch and the superior-posterior part of the C1 lateral mass not only minimizes neurovascular complications such as injury of the spinal cord, excessive bleeding from the venous plexus, and lesion of the vertebral artery but also prevents
Acknowledgments
The authors thank Sherryl Sundell for language editing and proofreading the manuscript. The authors also thank Dr. Jan Oliver Neumann for obtaining the intraoperative images.
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.