The importance of vertebral artery proximity to the odontoid process during anterior odontoid approaches.

The proximity of the vertebral artery (VA) to the odontoid process makes it vulnerable to injury during surgery. Knowledge of the quantitative anatomy of the VA groove is therefore necessary. In this study we assessed the spatial relationship between the VA and the odontoid process on cadavers by direct measurement and in patients by CT angiography. Our goal was to measure the distances from the VA and vertebrobasilar junction to the odontoid tip. The VA and odontoid process of 10 craniocervical cadavers ("cadavers") and of 20 patients were evaluated and average measurements obtained. The measured parameters were: (i) distance from the right VA to the odontoid tip (right VA-odontoid tip); (ii) distance from the left VA to the odontoid tip (left VA-odontoid tip), and (iii) distance from the vertebrobasilar junction to the odontoid tip (vertebrobasilar-odontoid tip). On the cadavers, the right VA-odontoid tip distance was 11.55mm, the left VA-odontoid tip was 11.02mm, and the vertebrobasilar junction-odontoid tip distance was 24.55mm. In patients, using CT angiography, the right VA-odontoid tip distance was 11.47mm and the left VA-odontoid tip distance was 11.50mm. The VA-odontoid tip distance is important in anterior odontoid approaches. Since the odontoid process may be in close contact with the VA, the relationship between them should be evaluated preoperatively in all candidates for odontoid surgery using three-dimensional CT angiography.

Anatomical study of axis for odontoid screw thickness, length, and angle.

Anterior odontoid screw fixation is a safe and effective method for treatment of odontoid fractures. The screw treads should fit into the odontoid medulla, should pass the fracture line, and should pull fractured odontoid tip against body of axis in order to achieve optimum screw placement and treatment. This study has demonstrated optimal anterior odontoid screw thickness, length, and optimal angle for safe and strong anterior odontoid screw placement. Dry bone axis vertebrae were evaluated by direct measurements, X-ray measurements, and computerized tomography (CT) measurements. The screw thickness (inner diameter of the odontoid) was measured as well as screw length (distance between anterior-inferior point body of axis and tip of odontoid), and screw angle (the angle between basis of axis and tip of odontoid). The inner diameter of odontoid bone was measured as 6.5+/-1.9 mm, the screw length was 37.6+/-3.3 mm, and the screw angle was 62.4+/-4.7 on CT. There was no statistical difference between X-ray and CT in the measurements of screw thickness and angle. X-ray and CT measurements are both safe methods to determine the inner odontoid diameter and angle preoperatively. Screw length should be measured on CT only. To provide safe and strong anterior odontoid screw fixation, screw thickness, length, and angle should be known preoperatively, and these can be measured on X-ray and CT.

A neurosurgical view of anatomical evaluation of anterior C1-C2 for safer transoral odontoidectomy.

An anatomical study for evaluation of anterior C1-C2. To provide essential anatomic data for safer transoral odontoidectomy. The surface dimensions of the atlas vertebra and the transoral approach for odontoidectomy have been described in detail. Anterior arcus of C1 must be drilled out to reach odontoid process for transoral odontoidectomy. The thickness of anterior ring of C1 has not been studied before. Sixty, dried adult atlas and 60 axis vertebrae and ten cadaveric craniocervical specimens were measured for the following: (1) bony drilling depth (BDD), the distance from the anterior wall of anterior ring of C1 to anterior wall of odontoid; (2) minimum drilling diameter (MDD), distance of minimum C1 anterior ring removal for odontoid resection on horizontal plane; (3) maximum bony drilling diameter (MBDD), distance of maximum C1 anterior ring removal for odontoid resection on horizontal plane. Lateral border of this diameter is limited by medial borders of the lateral mass; (4) the widest odontoid diameters (WOD) on coronal sections were measured. On 60 atlas and axis vertebrae, the BDD was 7.0 +/- 1.2 mm on dry bones, the distance between the medial borders of the lateral mass (MBDD) was 16.1 +/- 1.5 mm, and the WOD on coronal sections (WOD) was 9.8 +/- 0.8 mm. On cadavers, the distance between the two edges of C1 anterior ring removal for odontoid resection (MDD) was 10.8 +/- 1.1 mm and the WOD on coronal sections (WOD) was 10.1 +/- 1.4 mm. An odontoid surgery through transoral approach is safe and feasible. A quantitative understanding of the anterior anatomy of C-1 and C-2 is necessary when considering transoral odontoid resection. In this study the authors define safe zones for anterior atlas and axis.

Effect of ascorbic acid treatment on endothelium-dependent and neurogenic relaxation of corpus cavernosum from middle-aged non-insulin dependent diabetic rats.

AIMS: The purpose of the present study was to investigate functional responses and nitric oxide synthase activity in the corpus cavernosum of young control, middle-aged control and middle-aged non-insulin dependent diabetic rats. METHODS: The animal groups were treated with ascorbic acid. RESULTS: Acetylcholine-mediated endothelium-dependent relaxation of cavernosal tissue was significantly attenuated from a maximum of 58.0 +/- 4.1% (1 mmol, n = 10) in young rats to 44.3 +/- 1.6% in aged-matched controls (P < 0.05) and to 23.3 +/- 2.8% in non-insulin-dependent diabetes mellitus rats (P < 0.01). These deficits in acetylcholine responsiveness were completely prevented by ascorbic acid treatment. Non-adrenergic non-cholinergic relaxations evoked by electrical field stimulation (0.5-64.0 Hz) in the corpus cavernosum of middle-aged control and non-insulin dependent (NID) diabetic rats are blunted and were not restored by ascorbic acid. The histochemical findings demonstrated a decrease of nicotinamide adenine dinucleotide phosphate-diaphorase staining in the cavernosal tissue obtained from middle-aged control rats and middle-aged diabetic rats. CONCLUSION: Partial correction by ascorbic acid may suggest the importance of reactive oxygen species and a therapeutic approach in impotent NID diabetic men.

Short-term effects of arsenic sulfur in deficits of contractile and relaxant responses on urinary bladder: pharmacological and structural changes.

INTRODUCTION: Our goal was to investigate the effects of arsenic sulfur (AsS) on the detrusor smooth muscle reactivity. MATERIAL AND METHODS: AsS (100 ppm microg/g) in drinking water was administered for 2 weeks to two groups of female Wistar rats. The contractile responses of urinary bladders to electrical field stimulation, carbachol, ATP and KCl, and the relaxant responses to ATP, adenosine and isoproterenol were examined. Urinary bladder strips were collected for light microscopic examination. RESULTS: Our results demonstrate that oral inorganic AsS exposure induced enhanced contractile and reduced relaxant responses in rats. We hypothesize that AsS is involved in deficiencies of isolated urinary bladder in rats. CONCLUSION: These functional and morphological changes may be important as an intermediate link in urinary bladder oncogenesis induced by AsS.