Anatomical considerations of C2 lamina for the placement of translaminar screw: a review of the literature.

PURPOSE: The thorough knowledge of C2 lamina anatomy is essential for the avoidance of complications during screw fixation. We performed a review of the literature, aiming to detect what was found about anatomical feasibility of C2 translaminar fixation in different populations, along with possible recommendations for the avoidance of complications, and to detect whether factors such as race or gender could influence axis lamina anatomy and fixation feasibility. METHODS: We performed a search in PubMed and Cochrane database of systematic reviews for studies which correlated axis lamina anatomy with fixation feasibility. We extracted data concerning measurements on C2 lamina, the methods and conclusions of the studies. RESULTS: Twenty-six studies met our inclusion criteria. The studies mainly focused on Asian populations. Male gender was generally related to larger anatomical parameters of C2 lamina. The use of a C2 translaminar screw with a diameter of 3.5 mm was generally feasible, even in children, but there was disagreement about risk of vertebral artery injury. Computed tomography was most frequently recommended preoperatively. Three-dimensional reconstruction was suggested by some authors. CONCLUSION: C2 lamina anatomy generally permitted screw fixation in most studies, but there was disagreement about risk of vertebral artery injury. Preoperative computed tomography was generally recommended, while, according to some authors, three-dimensional reconstruction could be essential. However, there is a relative lack of studies about non-Asian populations. More research could further illustrate the anatomy of C2 lamina, clarify the safety of axis fixation for more populations and perhaps modify preoperative imaging protocols.

Piriformis syndrome--an attempt to understand its pathology.

OBJECTIVE: Gross anatomy of the hip rotators and histology of the sciatic nerves in adult cadavers were studied, aiming to the identification of possible pathologic changes related to the piriformis syndrome (PS). MATERIAL: 50 cadavers were dissected; in 17 cases with macroscopical findings the sciatic nerves were harvested (34 sciatic nerves; 17 cadavers). History of low back or leg pain was not available. METHOD: Site anatomy and additional findings at the harvesting sites were recorded, such as anatomical variations, adhesions, hematomas etc. All nerves were additionally microscopically analyzed. In cases with findings at the dissection, the contralateral unaffected nerves served as controls. All the dissected nerves were conserved in 10% formalin solution, embedded in paraffin, stained with Hematoxylin and Eosin (H&E) and immunolabeled with antibodies against Neurofilament (NF). RESULTS: Both the H&E staining as well as the performed immunohistochemistry showed, to a variable degree, significant alterations in the structure of the affected nerves compared to the controls. CONCLUSIONS: These findings both in the local anatomy and sciatic nerve correspond to lesions that are expected in PS. Nevertheless, since this was a cadaveric study, unassociated to a certain pain patient's history, results should be considered and interpreted as an indication of a sciatic nerve injury in PS.

Spinal surgery in patients with Parkinson's disease: unsatisfactory results, failure and disappointment.

Previous studies on spinal surgery in PD patients report an exceptionally high rate of complications. Failure and re -operation are frequent outcomes. This is a retrospective case series with the aim of establishing the rate of complications in patients with concomitant Parkinson's disease. Ten patients were subjected to spinal surgery from 2005 to 2009. The indications and type of operation varied. Cases of Failed Back Surgery and re-operation were sought. Follow - up was between 6 - 42 months. All 10 patients presented some clinical or radiological complication. The most common complications were screw pull - out and progressive spinal deformity. Re - operations were performed in 5 patients, while clinical and radiological results were poor in the majority of cases. Patients with Parkinson's disease have a very high complication rate and often have to undergo revision surgery. This particular group of patients should be informed of the increased risk of failure and be closely followed - up on a regular basis.