Introduction: Numerous methods of achieving occipito-cervical stabilization have been described, including the use of occipital plate/screw construct. Bicortical screw may increase the pullout strength, but the potential for intracranial injuries to venous sinuses have been reported. This study was performed to analyze the variations of occipital sinuses to prevent sinus injury by the bicortical screw.
Methods: Occipital sinuses of one 1720 patients were examined using DSA. The data were collected: patient’s age, gender, occipital sinus type, distance between occipital sinus and midline, depth from inion to occipital sinus and the distance between the occipital sinus and the midline occiput in different levels.
Results: The mean age of the patients was 57 ± 13 years. Eight hundred and seven (46.9%) patients were male and nine hundred and thirteen (53.1%) were female. The highest occurrence was noted on patients having single occipital sinus (Type B), with a higher prevalence of off-midline sinus (Type B2, 31.9%) than midline sinus (Type B1, 24.3%). The next most common distribution was double sinuses (Type C, 23.9%), followed by multiple sinuses (Type D, 11.2 %). The lowest occurrence was in patients with absent occipital sinuses (Type A, 8.7%). There was no significant difference between age and occipital sinus type (p=0.310). Also, the difference between genders was not significant in occipital sinus type in general. However in subgroup analysis of type B, presentation of occipital sinus type was significantly different between genders (p<0.01).The mean depth from bone to occipital sinus was 19.913 ± 7.437mm. The distance from the outer cortex of occiput to the occipital sinus tapered rapidly away from cranial to caudal.
Conclusions: The occipital sinus shows several variations can be seen. Therefore, preoperative detailed examination by MRV or vertebral angiography may be required for the cases in which bicortical occipital screw fixation is necessary to avoid occipital sinus related complication.
Patient Care: The preoperative detailed examination by MRV or vertebral angiography may be required for the cases in which bicortical occipital screw fixation is necessary to avoid occipital sinus related complication.
Learning Objectives: By the conclusion of this session, the occipital sinus shows several variations and many morphological differences can be seen. Therefore, preoperative detailed examination by MRV or vertebral angiography may be required for the cases in which bicortical occipital screw fixation is necessary to avoid occipital sinus related complication.