No abstract

This study indicates that improper placement of the pedicle screw medially and superiorly in the middle and lower cervical spine should be avoided and that the anatomic variations between individuals should be established by measurement.

The anatomy of the branches of the anterior cerebral artery (ACA) near the anterior communicating artery (ACoA) complex were investigated to minimize neurovascular morbidity caused by surgical procedures performed in this region. Thirty-one cadaver brains were perfused with colored silicone, fixed, and studied under the operating microscope. The recurrent artery of Heubner (RAH), orbitofrontal artery (OFA), and frontopolar artery (FPA) were identified as the branches of the ACA arising near the ACoA complex. The OFA and FPA were identified in all hemispheres. Forty-nine (64%) of a total of 77 RAHs arose from the A 2 segment. The OFA always arose from the A 2 segment, was consistently the smallest branch, and coursed to the gyrus rectus, olfactory tract, and olfactory bulb. The mean distance between the ACoA and the OFA was 5.96 mm. The FPA arose from the A 2 segment in 95% of the specimens, and coursed to the medial subfrontal region. The mean distance between the ACoA and the FPA was 14.6 mm. The RAH, OFA, and the FPA are three branches that arise from the ACA near the ACoA complex. These vessels have similar diameters, but can be distinguished by the final destination. Distinguishing these vessels is important since the consequences of injury or occlusion of the FPA and OFA are significantly less than of the RAH.

Between the years 1970 and 1997, 112 patients with tumors of the lateral ventricle were operated on at the University of Ankara, School of Medicine, Department of Neurosurgery. Seventy-one patients (63.4%) were male and 41 patients (36.6%) female. Headache (35.7%), nausea and vomiting (22.3%) were the most common presenting complaints. Papilloedema (42.9%), motor and sensory loss (25%) were the most common findings at neurological examination. Complete tumor removal was accomplished in 38.4% of the patients. Histopathologically, the most commonly seen types of the tumor were ependymoma (25%) and astrocytoma (21.4%). Among the various approach, the anterior transcortical (53.6%) and the posterior transcortical (16%) were the most commonly used. Eleven patients were reoperated for tumor recurrence. After surgery, radiation therapy was also performed on fourty-two patients. The morbidity and mortality rates were considerably higher before 1976 when the use of microneurosurgical techniques was introduced. After this, our morbidity and mortality rates decreased dramatically. The overall surgical mortality rate was 7.1% before 1976; during the last 10 years (n:46), it was 6.5%. In this report, our choice of operative approaches and the results will be discussed.

IntroductionTranspedicular screw fixation can be used for the treatment of unstable lumbar spine caused by trauma, tumors, infections, and degenerative conditions. Instrumentation techniques of the spine using the pedicle from posterior into the vertebral body have become popular recently, because of the advantages of these systems [1, 3,4,5,6,10,11,12,13]. Pedicle screw placement does not pose the same high risk of damage to the spinal cord, dural sac, and nerve roots in the lumbar region as it does in thoracic and cervical spine. However, accurate anatomic knowledge is needed to perform a safe surgical intervention in the lumbar region [2,9,11]. Despite the growing interest in pedicle instrumentation in the lumbar spine, the anatomic relationships of lumbar pedicle have not yet been analyzed adequately for the safe performance of these clinical applications. Even though some of the measurements duplicate previous studies, and the data presented in this study are limited to the surrounding tissues of the pedicle, we consider such that information is necessary for building Abstract Although several clinical applications of transpedicular screw fixation in the lumbar spine have been documented for many years, few anatomic studies concerning the lumbar pedicle and adjacent neural structures have been published. The lumbar pedicle and its relationships to adjacent neural structures were investigated through an anatomic study. Our objective is to highlight important considerations in performing transpedicular screw fixation in the lumbar spine. Twenty cadavers were used for observation of the lumbar pedicle and its relations. After removal of whole posterior bony elements including spinous processes, laminae, lateral masses, and inferior and superior facets, the isthmus of the pedicle was exposed. Pedicle width and height (PW and PH), interpedicular distance (IPD), pedicle-inferior nerve root distance (PIRD), pedicle-superior nerve root distance (PSRD), pedicle-dural sac distance (PDSD), root exit angle (REA), and nerve root diameter (NRD) were measured. The results indicated that the average distance from the lumbar pedicle to the adjacent nerve roots superiorly, inferiorly and to the dural sac medially at all levels ranged from 2.9 to 6.2 mm, 0.8 to 2.8 mm, and 0.9 to 2.1 mm, respectively. The mean PH and PW at L1-L5 ranged from 10.4 to 18.2 mm and 5.9 to 23.8 mm, respectively. The IPD gradually increased from L1 to L5. The mean REA increased consistently from 35°to 39°. The NRD was between 3.3 and 3.9 mm. Levels of significance were shown for the P<0.05 and P<0.01 levels. On the basis of this study, we can say that improper placement of the pedicle screw medially and inferiorly should be avoided.