Posterior Inferior Cerebellar Artery Infarction Originating at C1-2 after C1-2 Fusion / 대한신경손상학회지

Vertebral artery injuries associated with C1 lateral mass screw insertion rarely occur during C1-2 fusion. The posterior inferior cerebellar artery (PICA) is uncommonly located at the C1 lateral mass insertion position. A 71-year-old woman with atlanto-axial subluxation and cord compression underwent C1-2 fusion. Sixth nerve palsy and diplopia were detected postoperatively, and decreased consciousness occurred on postoperative day 4. Brain magnetic resonance image (MRI) and computed tomography (CT) revealed PICA infarction. In the preoperative CT angiography, the PICA originated between the C1 and C2 level. In the postoperative CT scan, the PICA was not visible. The patient was treated conservatively for two weeks and recovered. PICA originating between the C1 and C2 level comprises 1.1–1.3% of cases. Therefore, vertebral artery anomalies should be evaluated prior to C1-2 fusion to prevent vessel injuries.

Minimally Invasive Microscope-Assisted Stand-Alone Transarticular Screw Fixation without Gallie Supplementation in the Management of Mobile Atlantoaxial Instability

STUDY DESIGN: Retrospective study. PURPOSE: To evaluate the clinico-radiological efficacy of stand-alone minimally invasive transarticular screw (MIS-TAS) fixation without supplemental Gallie fixation in the management of mobile C1–C2 instability. OVERVIEW OF LITERATURE: Data evaluating the efficacy and feasibility of MIS-TAS in the literature is scanty. METHODS: Patients with mobile atlantoaxial instability and >2 years follow-up were included and managed by stand-alone TAS fixation using the Magerl technique and morselized allograft without additional fixation. Patient demographics and intra-operative parameters were noted. Clinical parameters (Visual Analog Scale [VAS] and Oswestry Disability Index [ODI]), neurology (modified Japanese Orthopaedic Association [mJOA]), and radiological factors (anterior atlanto-dens interval and space available for cord) were evaluated pre and postoperatively. Computed tomography (CT) was performed in patients who did not show interspinous fusion on X-ray at 1 year, to verify intra-articular fusion. Statistical analysis was performed using IBM SPSS ver. 20.0 (IBM Corp., Armonk, NY, USA); the Student t-test and analysis of variance were used to assess statistical significance (p <0.05). RESULTS: A total of 82 consecutive cases (three males, one female; mean age, 36.26±5.78 years) were evaluated. In total, 163 TASs were placed. Significant improvement was noticed in clinical (mean preoperative VAS=7.2±2.19, postoperative VAS=3.3±1.12; mean preoperative ODI=78.3±4.83, postoperative ODI=34.05±3.26) and neurological features (mean preoperative mJOA=14.73±2.68, postoperative mJOA=17.5±2.21). Radiological evidence of fusion was noted in 97.5% cases at final follow-up. Seventeen patients were found to have no interspinous fusions upon X-rays, but CT revealed facet fusion in all patients except in two. Inadvertent vertebral artery injury was noted in three cases. CONCLUSIONS: Stand-alone TAS fixation with morselized allograft provides excellent radiological and clinical outcomes. The addition of a supplementary tension band and structural graft are not essential. This provides the opportunity to avoid the complications associated with graft harvesting and wiring.

C2 Anatomy for Translaminar Screw Placement Based on Computerized Tomographic Measurements

STUDY DESIGN: Anatomical study. PURPOSE: To evaluate the anatomy of the C2 lamina for translaminar screw placement based on computerized tomographic measurements. OVERVIEW OF LITERATURE: C2 translaminar screw insertion is a novel technique for atlanto-axial fixation. The risk of vertebral artery injury can be decreased by this technique. However, a large series of anatomical studies on C2 anatomy in Asian populations is still lacking. METHODS: Two hundred adult C2 vertebrae were evaluated by computerized tomographic imaging. The measured parameters included inner and outer transverse diameters of C2 lamina, C2 laminar length and spino-laminar angle. C2 vertebrae with lamina screw placement feasibility were defined as those with inner transverse diameter larger than 3.5 mm. RESULTS: The mean inner transverse diameter of the C2 lamina was 4.23+/-1.22 mm. It was significantly larger in males than in females (4.44+/-1.29 mm vs. 3.96+/-1.06 mm, p=0.005). The mean outer transverse diameter of C2 lamina was 6.64+/-1.36 mm. The mean C2 laminar length was 37.26+/-4.42 mm. The mean C2 spino-laminar angle was 56.42+/-6.42 degrees. Seventy-nine percents of patients had inner transverse diameter larger than 3.5 mm. CONCLUSIONS: C2 translaminar screw fixation was feasible in the majority of the adult population. However, there were some people who had small C2 lamina. We recommend preoperative computed tomography evaluation to confirm the feasibility of screw placement.

Combined Chronic Occipito-atlantal and Atlanto-axial Rotator Fixation with Cerebral Palsy

Occipito-atlantalrotatory subluxation that occurs in conjunction with atlanto-axial rotator fixation is extremely rare. The common clinical characteristics are painful torticollis and cock robin position presented with the head tilted to one side and rotated to the other side. The object of this report is to emphasize that AARF combined with OARF may be caused by a variety of conditions, to be must need algorithm for proper management, apparently. A torticollis patient who had cerebral palsy presented with severe nuchal pain and wryneck for a long period. The patient had a history of fallen down 16 years ago which caused severe nuchal pain. The conservative management had failed to correct the deformity and instability. we decided to operate using occiput-C1-C2 arthrodesis and C3-4-5 bilateral screw fixation for reinforcement. Now he doesn't have neurologic deficit and shows good outcome enough to sustain his head, not using his hands, in his daily life.

O-arm(R) Imaging System Coupled with Navigation Guided Posterior Atlantoaxial Screw Fixation in the Patient with Ponticulus Posticus, an Anatomical Variation of Atlas

Ponticulus posticus is an abnormal bony bridge of posterior arch of atlas. The resulting foramen contains the vertebral artery and has clinical significance in lateral mass screw insertion into the first cervical vertebra. The authors report an atlantoaxial subluxation case showing a ponticulus posticus, which was surgically treated with posterior atlantoaxial screw fixation under the guidance of O-arm(R) imaging system coupled with navigation.