Effects of preexisting bypass graft on rCBF and SSEP's following acute stroke in dogs

Regional cerebral blood flow (rCBF) was measured with radiolabeled microspheres in a canine model of superficial temporal artery-middle cerebral artery (STA-MCA) bypass and acute ischemia. Ischemic zone flows in seven dogs with the bypass first closed and then open showed no significant contribution of bypass flow in the intact vascular system. Following acute proximal occlusion, rCBF was preserved by bypass flow. A significant flow decrease ensued when the bypass was then clipped, confirming the adequacy of the lesion and the protective effect of the bypass. Reopening the bypass after 15 minutes of ischemia restored 76% of the previous flow. This was a significant increase from the global ischemia values, and was not statistically different from preocclusive values. Preocclusion somatosensory evoked potentials (SSEP's) in these animals showed a consistent biphasic wave at 8 to 10 msec after stimulation. This wave, with some decrease in amplitude, was preserved by bypass flow following creation of the arterial lesion. Bypass clipping abolished these ipsilateral SSEP's. Variable return of SSEP's occurred following reopening of the graft, but the recordings never reached preischemic amplitudes. This experimental study shows that, in this model, a prophylactic bypass subjected to immediate demand (with no time for "maturation") can adequately augment cortical rCBF and is superior to delayed revascularization. The data lend theoretical support to placement of a prophylactic STA-MCA bypass prior to elective carotid artery sacrifice or in surgery where the risk of acute vascular injury is high.     

Stereotactic Radiosurgery Versus Microsurgical Resection for the Initial Treatment of Metastatic Cancer to the Brain

The use of Stereotactic radiosurgery for the treatment of intracranial metastases from systemic cancer has grown considerably in the last few years. Review of the literature, however, reveals a paucity of well-controlled studies to substantiate this expansion. We conducted this study to address the issue of survival after treatment with either stereotactic radiosurgery or surgical resection. Whole brain radiation was instituted in both treatment arms. This was a retrospective, case-controlled study comparing patients whose only treatment for intracranial disease was either stereotactic radio-surgery or a single surgical resection. Controlling for age, histology, whole brain radiation, tumor size, number of intracranial lesions, and pre-procedural Karnofsky performance scores, we believe this study to be the most rigorous analysis to date. Patients in the radiosurgery group survived longer (median survival = 12.5 months) than those in the surgically resected group (median survival = 8 months). Statistical analysis of these curves did not show a significant difference. Considering only length of patient survival, there is no statistical difference between stereotactic radiosurgery and microsurgical resection for the treatment of new brain metastases from systemic cancer. This conclusion is based on strict criteria as outlined in the text. A larger, prospective, randomized investigation is needed to more definitively address the issue.     

Frequency and spectrum of outpatient musculoskeletal diagnoses at a pediatric hospital in Kenya

Clinical Rheumatology - Chronic pediatric musculoskeletal (MSK) conditions are a major cause of morbidity. The burden of pediatric rheumatic diseases in East Africa is largely unknown. The purposes...     

Sm antibodies increase risk of death in systemic lupus erythematosus

The importance of ethnicity, socioeconomic status (SES), and autoantibodies as prognostic indicators in lupus were evaluated in a Canadian cohort. A retrospective review of 330 lupus patients identified demographic features including age and self reported ethnicity, SES, lupus features, antibodies to extractable nuclear antigens (ENAs), organ damage (SDI score), and mortality. ENA (Sm, RNP, Ro, La) associations with lupus features, predictors of final visit SDI score and the contributions of ethnicity, autoantibodies and SES on overall mortality were determined. Three ethnic groups [Caucasians (C), Asian-Orientals (AO), Native American First Nations (FN)] differed in disease severity and SES. FN and AO patients had similarly severe lupus, developing lupus at an earlier age, with more renal and neurological involvement, greater SDI scores at last visit, and more frequently had Sm or RNP antibodies than C. FN had the highest mortality and lowest SES. Sm and RNP antibodies were associated with renal and neurologic involvement. RNP, education and duration of follow-up predicted SDI score. Sm increased risk of death. In conclusion, RNP and lower SES are associated with lupus related organ damage and the presence of Sm is a predictor of mortality in lupus, independent of ethnicity, renal involvement or socioeconomic status.     

In vitro biomechanical comparison of transpedicular versus translaminar C-2 screw fixation in C2-3 instrumentation

OBJECT: In instrumentation of the upper cervical spine, placement of pedicle screws into C-2 is generally safe, although there is the potential for injury to the vertebral arteries. Owing to this risk, translaminar screws into C-2 have been used. The aim of this study was to compare the stability of the in vitro cadaveric spine using C-2 laminar compared with C-2 pedicle screws in C2-3 instrumentation. METHODS: Eight fresh frozen human cadaveric cervical spines (C1-6) were potted at C1-2 and C5-6. Pure moments in increments of 0.3 Nm to a maximum of 1.5 Nm were applied in flexion, extension, right and left lateral bending, and right and left axial rotation. Each specimen was tested sequentially in three modes: 1) intact; 2) C2 pedicle screw-C3 lateral mass fixation; and 3) C2 laminar screw-C3 lateral mass fixation. The sequence of fixation testing was randomized. Motion was tracked with reflective markers attached to C-2 and C-3. RESULTS: Spinal levels with instrumentation showed significantly less motion than the intact spine in all directions and with all loads greater than 0.3 Nm (p < 0.05). Although there was no significant difference between C2 pedicle screw-C3 lateral mass fixation and C2 laminar screw-C3 lateral mass fixation, generally the former type of fixation was associated with less motion than the latter. CONCLUSIONS: When pedicle screws in C-2 are contraindicated or inappropriate, laminar screws in C-2 offer a safe and acceptable option for posterior instrumentation.