Clinical use of a frameless stereotactic arm: results of 325 cases

The viewing wand is a frameless stereotactic arm that can be used in conjunction with computerized tomography (CT) or magnetic resonance (MR) imaging to provide image-based intraoperative navigation. The authors report a series of 325 cases in which the viewing wand was used and evaluated for its utility, ease of integration into the standard surgical setup, reliability, and real-world accuracy. The use of the system was associated with minimal additional effort or time spent in setting up the procedure as long as a trained technician performed the data transfer and reconstruction. The viewing wand was used in 165 cases in conjunction with CT and 145 cases with MR imaging. The system was reliable, achieving a useful registration in 310 of 325 cases (95.4%). Fiducial-based registration was more accurate than an anatomical landmark-surface fit algorithm method of registration (mean 2.8 vs. 5.6 mm error, respectively, for CT; and mean 3.0 vs. 6.2 mm for MR imaging). The actual error of the system in estimating the position of the probe tip just after registration was judged by the operating surgeon to be less than 2 mm in 92% of MR imaging cases and in 82% of CT cases, between 2 and 5 mm in 7% of MR imaging and 17% of CT cases, and greater than 5 mm in less than 1% of MR imaging and 1.2% of CT cases. The accuracy of the system degraded during the operation, so that by the third evaluation the error was estimated to be less than 2 mm in 77% of MR imaging and 62% of CT cases. Overall, the viewing wand was found to be reliable and accurate. This real-world accuracy was sufficient for a broad range of applications including glioma resection, cerebrospinal fluid shunting procedures, resection of small subcortical masses, and temporal lobe resection. The system is a useful navigational aid that allows a direct approach to intracranial pathology without the drawbacks of application and the limitations of a stereotactic frame.

Cervical-to-petrous internal carotid artery bypass procedure. Technical note

The technique for cervical-to-petrous internal carotid artery saphenous vein bypass is described. This procedure was used in the treatment of three patients with high cervical or skull base vascular injuries. All grafts were patent on follow-up angiography.

Facet fracture-dislocation injuries of the cervical spine

Sixty-eight patients with acute traumatic cervical facet fracture-dislocation injuries are presented. These patients represented 6.7% of all cervical spine fractures identified over a 12-year period. Thirty-one patients had unilateral facet injuries and 37 had bilateral facet injuries. Neurological morbidity was 90% and was most severe among bilateral facet injury patients (84% complete injuries). Spinal shock was identified in 13 patients and was a poor prognostic indicator for the subsequent recovery of associated neurological deficits. Closed reduction was attempted in 66 of 68 patients and was successful in 58% of the patients. Seven patients deteriorated. Open reduction-internal fixation was successful in 83% of 24 patients with a 4% morbidity. Seventy-eight percent of patients improved with rapid closed reduction, and 60% improved with open reduction-internal fixation; however, only 10 patients of the entire 68 made significant neurological recoveries. In these 10 patients, the timing of decompression-realignment appeared to be more important than the means of reduction.

Moxalactam penetration into normal heart valve, cardiac vegetations, and myocardium in relation to protein binding and physiological distribution spaces

Rabbits with catheters implanted in the left ventricle were given a single dose of moxalactam and sacrificed at various times thereafter for measurement of the concentration of this antimicrobial agent in serum, heart muscle, and various heart valves. Penetration into both extravascular sites was rapid; steady state was achieved within 5 min after the dose. Moxalactam showed essentially complete penetration into valve lesions, whereas concentrations in heart muscle were only 20% of those in serum. The physiological distribution of moxalactam in heart muscle was beyond the inulin space, but substantially lower than total body water. This myocardial distribution ratio was not predicted by the serum-free fraction or blood trapped in tissues alone, but was in good agreement with that of extracellular fluid plus blood trapped in tissues. The moxalactam distribution profile was most compatible with that of drugs which are excluded from cells but readily distributed throughout extracellular fluids. This explains its nearly complete penetration into heart valves as well as its incomplete penetration into heart muscle, since the two sites differ in their relative proportions of cells and extracellular fluid spaces.