Neurochirurgie 67 (2021) 310–314 Disponible en ligne sur ScienceDirect www.sciencedirect.com Original article PICA injury secondary to anterior odontoid screw fixation: Case report of an exceptional complication夽 K. Farah a,∗ , M. Meyer a , A. Reyre b , K. Cot c , S. Fuentes a a b c Neurosurgery department, Aix-Marseille University, APHM, CHU Timone, Marseille, France Endovascular neuroradiology department, Aix-Marseille University, APHM, CHU Timone, Marseille, France Anesthesiology–intensive care department, Aix-Marseille University, APHM, CHU Timone, Marseille, France a r t i c l e i n f o Article history: Received 8 October 2020 Received in revised form 15 February 2021 Accepted 28 February 2021 Available online 19 March 2021 Keywords: Odontoid fracture Complication Anterior fixation Iatrogenic PICA injury Pseudoaneurysm a b s t r a c t Background. – Odontoid fracture is a common injury in the upper cervical spine that can sometimes be managed by anterior odontoid screw fixation. Case description. – We report the first case of iatrogenic postero-inferior cerebellar artery (PICA) injury while performing anterior odontoid screw fixation for a type II odontoid fracture in a 22-year-old man. Fisher grade 4 subarachnoid hemorrhage secondary to iatrogenic pseudoaneurysm formation was managed by the endovascular neuroradiologist. Odontoid fracture was then managed posteriorly using Harm’s technique. Postoperative 12-month follow-up revealed good clinical and radiological results. CT scan showed fusion. Complete exclusion of the pseudo aneurysm with a mild stroke in the inferior left cerebellar hemisphere were noted on the MRI. There were no cerebellar ataxia or swallowing disorders. Conclusion. – To the best of our knowledge, this is the first case report of iatrogenic PICA injury in anterior odontoid screw fixation. The patient was well managed in our institution within a multidisciplinary team. We recommend that surgical management of odontoid fractures should be performed in expert centres. © 2021 Elsevier Masson SAS. All rights reserved. 1. Introduction 2. Case report Odontoid fracture is a common injury in the upper cervical spine. It accounts for 10% to 16% of all cervical spine fractures [1,2]. According to the classification of Anderson and D’Alonzo [3], almost 60% of these fractures are type II cases. Type II fractures and shallow type III odontoid fractures are recognised as mechanically unstable and associated with a high incidence of non-union or mortality [3–8] and therefore surgical stabilization is recommended [9,10]. Some complications may occur during anterior cervical spine surgery and among these, vascular injury has potentially devastating neurovascular consequences. We report the first case of iatrogenic PICA injury while performing anterior odontoid screw fixation for a type II odontoid fracture in a 22-year-old man. 2.1. Clinical history 夽 This paper has not been presented (nor published) previously. ∗ Corresponding author. E-mail addresses: kaissar.farah@gmail.com, bazramit@hotmail.com (K. Farah). https://doi.org/10.1016/j.neuchi.2021.02.015 0028-3770/© 2021 Elsevier Masson SAS. All rights reserved. A 22-year-old man was assessed to our institution from another neurosurgical department for the management of iatrogenic left PICA injury during anterior odontoid screw fixation for posttraumatic type II odontoid fracture under fluoroscopic control. The initial surgeon reported CSF leakage with bleeding when retrieving the K-wire during anterior odontoid screw insertion. At admission to our institution, patient was under sedation with endotracheal intubation. Initial cerebral and cervical spine CT-scan revealed pneumocephalus and perimesencephalic subarachnoid hemorrhage (SAH) with mild contamination of the ventricles without hydrocephalus (Fisher grade 4) (Fig. 1) and inappropriate odontoid anterior screw positioning. Due to SAH, a first cerebral angiography was performed revealing a 1.5*2 mm pseudoaneurysm of the second segment of the left PICA with downstream stenosis and delayed filling on parenchymography of the left PICA territory. K. Farah et al. Neurochirurgie 67 (2021) 310–314 Fig. 1. Head CT scan at admission showing (A) pneumocephalus (black arrow) and Fisher grade 4 perimesencephalic subarachnoid hemorrhage (black arrow) with mild contamination of the 4th ventricle. 2.2. Surgical management After a multidisciplinary discussion (neurosurgeons, endovascular neuroradiologists and anesthesiologists), initial management consisted in close clinical and radiological follow-up. Therefore, a second cerebral angiography was performed 2 days later showing a 1.5 mm growth of the pseudoaneurysm. Coiling of the pseudoaneurysm was decided and performed with complete occlusion of the aneurysm’s sac. Left PICA was still permeable on the final control (Fig. 2). A week later, the cerebral angiography control revealed recanalisation of the pseudoaneurysm within its neck, and the appearance of a second pseudoaneurysm on the other side of the left PICA (mirror pseudoaneurysm). After a new multidisciplinary discussion, we decided a segment occlusion of the left PICA with coiling and onyx due to the high bleeding risk. The final control shows an occlusion of the left PICA at the dissecting aneurysm level (Fig. 3). More distally, the artery is partially recovered by neighbouring anastomosis. When the patient was out of risk for rebleeding and pseudoaneurysms were controlled, he underwent posterior C1–C2 fixation according to Harms’ technique [11]. The anterior odontoid screw was not removed as it did not present any harmful position and in order to avoid complications secondary to a revision surgery. 2.3. Postoperative course After 2 weeks in the intensive care unit, the patient was transferred to our neurosurgical department. Clinical examination revealed a GCS of 15 out of 15, a mild left cerebellar syndrome with left dysmetria and disdiadochokinesia with mild swallowing disorders. A cerebral MRI was performed and revealed mild infarction within left PICA territory with disappearance of the SAH. No hydrocephalus was noted. A spine CT-scan obtained 2 days postoperatively demonstrated adequate screw positioning with no medial breach nor with transverse foramen obstruction and no further displacement of the fracture (Fig. 4). He was released to a rehabilitation centre 3 weeks after initial admission. A 12-month postoperative CT-scan showed fusion of the fracture. The anterior odontoid screw was still in place. Cerebral MRI Fig. 2. Cerebral angiography (left vertebral artery, lateral view) performed. A. On admission revealing a 1.5*2 mm pseudoaneurysm (grey arrow) of the second segment of the left PICA with downstream stenosis and delayed filling on parenchymography of the index territory. B. Four days after admission showing a 1.5 mm growth of the pseudoaneurysm. Coiling was performed. Left PICA was still permeable on the final control. 311 K. Farah et al. Neurochirurgie 67 (2021) 310–314 Fig. 3. Cerebral angiography (left vertebral artery, lateral view) performed on day 11 after admission showing (A) recanalisation within the neck (grey arrow). (B) Segment occlusion of the left PICA with coiling and onyx due to the high bleeding risk was decided (grey arrow), and therefore (C) the left PICA is no more enhanced (grey arrow). Fig. 4. Postoperative day 2 spine CT-scan showing adequate screw positioning on (A) parasagittal and (B) sagittal (C) and axial slides with neither medial breach nor with transverse foramen obstruction and no further displacement of the fracture. Note the previous trajectory of the anterior odontoid screw. Fig. 5. Cerebral MRI. A. Two weeks post-admission, axial hyperFLAIR intensity revealing mild infarction within left PICA territory (white arrow) with disappearance of the SAH. B. At 6 months follow-up showing a mild stroke in the inferior left cerebellar hemisphere (white arrow) on axial FLAIR sequence and (C) complete exclusion of the pseudo aneurysm and left PICA (white arrow) on TOF sequence. revealed complete exclusion of the pseudo aneurysm with a mild stroke in the inferior left cerebellar hemisphere (Fig. 5). The patient reported no neck pain. There was no cerebellar ataxia or swallowing disorders. No wound problems were to be reported. 3. Discussion Management of type II odontoid fracture is still controversial. Several factors can determine treatment’s strategy: Age, fracture’s orientation, osteoporosis, comorbidities, vertebral artery anatomy, osseous anomalies [12] and surgical team experience. Management can be conservative or surgical. When surgery is selected, surgeons dispose of 3 alternatives: Anterior screw fixation, C1 lateral mass and C2 pedicle fixation also known as Harm’s technique or C1–C2 transarticular fixation also known as Magerl’s technique [13]. Although there are circumstances that require posterior fixation, anterior odontoid screw fixation confers several advantages, such as maintenance of atlantoaxial rotation, shorter operative 312 K. Farah et al. times and reduced vertebral artery injury and bleeding risk [14,15]. Neurochirurgie 67 (2021) 310–314 Human and animal rights The authors declare that the work described has not involved experimentation on humans or animals. 3.1. Complication In a retrospective study reporting short-term complications of anterior fixation of odontoid fractures in 103 patients with a mean age of 73.9 years (19–90), complications occurred in 37.9% of patients. Major complications consisted in death in 7 patients, unplanned reoperation in 6 patients, failure to wean/re-intubation in 5 patients, myocardial infarction in 2 patients, sepsis in 2 patients and stroke in 2 patients. Minor complications were blood transfusion in 23 patients, pneumonia in 4 patients and urinary tract infection in 3 patients [16]. In another retrospective multicentre study including 14,722 patients, Lee et al. reported that surgery-specific incidence of iatrogenic vertebral artery injury was 1.35% in cases involving C1–2 posterior fixation and 0.20% in cases involving C3–6 posterior fixation. Common injury mechanisms were screw-in (31%) and high-speed drilling (23%). Of 13 cases of iatrogenic vertebral artery injury, 3 (23%) involved cerebellar or stem infarction; the infarction had no substantial correlation with injury grade or dominancy [17]. Incidence vary in the literature as vertebral artery injury (and/or PICA injury) with cerebellar infarction or brain stem infarction can occur in 1.7 to 5% of patients who underwent surgery using C1–C2 transarticular fixation [18–20]. Due to the technically more demanding method of Magerl’s technique, the use of Harms’ technique is contemporary more popular [12]. However, Yoshida et al. reported that C2 pedicle screw placement has the same anatomic risk of the VA injury as transarticular screw placement [21]. Injury of the PICA is mostly reported in posterior fixation with aberrant artery anatomy [22]. Several other studies examined complications and mortality in patients treated with anterior odontoid screw fixation [16,23–25]. Among these studies, none had reported PICA injury during anterior odontoid screw fixation. We hereby report the first case concerning this exceptional iatrogenic complication. 3.2. Management In our case, complication was managed in our expert centre where intensive care unit, endovascular neuroradiologist and neurosurgeon are present. The posterior fixation using the Harm’s technique is considered in our case as a viable salvage in the failed anterior odontoid fixation. At last follow-up, clinical and radiological (both healing of the fracture and angio-cerebral MR) results are very satisfying comparing to the initial condition at admission. We therefore stress on the necessity to perform this kind of surgery in centres where all previously cited actors are present and work closely together in order to rapidly manage complications that can sometimes be deadly. Surgery for odontoid fracture should also be managed by an expert surgeon, as there surely is a learning curve that cannot be neglected. Nowadays, there are many tools that can technically help surgeon in daily routine for the management of these fractures such as intraoperative 3D-navigation [26]. 4. Conclusion To the best of our knowledge, this is the first case report of iatrogenic PICA injury in anterior odontoid screw fixation. The patient was well managed in our institution within a multidisciplinary team. We recommend that surgical management of odontoid fractures should be performed in expert centres. Informed consent and patient details The authors declare that this report does not contain any personal information that could lead to the identification of the patient(s) and/or volunteers. Disclosure of interest The authors declare that they have no competing interest. 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