Background and Purpose Acute cerebral ischemia after subarachnoid hemorrhage (SAH) is a major cause of morbidity whose precise etiology is unclear. The purpose of this study was to examine the relationships between cerebral perfusion pressure (CPP) and cortical blood flow during SAH using a new experimental model in the rat. Methods CPP (mean arterial pressure minus intracranial pressure), cortical laser-Doppler flowmetry (LDF), and electroencephalogram were continuously recorded during and after SAH in 16 ventilated rats. SAH was produced by advancing an intraluminal suture from the external carotid artery through the internal carotid artery to perforate the vessel near its intracranial bifurcation. Results Eight rats (50%) died within 24 hours of SAH. In all rats, blood was widely distributed throughout the basal, convexity, and interhemispheric subarachnoid spaces and throughout the ventricular system. CPP decreased after SAH at an initial rate of 1.1±0.2 mm Hg/s, reaching its nadir 59±9 seconds after the onset of SAH. During the same period, LDF fell at a rate of 1.4±0.3%/s ( P =NS vs CPP). After reaching its nadir, CPP rose at a rate of 0.4±0.01 mm Hg/s, but LDF continued to fall at 0.2±0.03%/s ( P <.05 vs CPP) reaching a nadir of 21.7±2.5% significantly later than CPP (189.5±39 s after SAH, P <.05). No correlation was found between peak changes in CPP and LDF. Electroencephalogram activity followed the changes in LDF, reaching nadir values 289±55 seconds after SAH. Conclusions These findings demonstrate that although reduced CPP causes the initial decrease in cortical blood flow after SAH, secondary reductions occurring after CPP has reached its nadir are caused by other factors such as acute vasoconstriction. This noncraniotomy model of SAH in the rat has several advantages over existing models.

Preface: The leadership of Women in Neurosurgery (WINS) has been asked by the Board of Directors of the American Association of Neurological Surgeons (AANS) to compose a white paper on the recruitment and retention of female neurosurgical residents and practitioners. Introduction: Neurosurgery must attract the best and the brightest. Women now constitute a larger percentage of medical school classes than men, representing approximately 60% of each graduating medical school class. Neurosurgery is facing a potential crisis in the US workforce pipeline, with the number of neurosurgeons in the US (per capita) decreasing. Women in the Neurosurgery Workforce: The number of women entering neurosurgery training programs and the number of board-certified female neurosurgeons is not increasing. Personal anecdotes demonstrating gender inequity abound among female neurosurgeons at every level of training and career development. Gender inequity exists in neurosurgery training programs, in the neurosurgery workplace, and within organized neurosurgery. Obstacles: The consistently low numbers of women in neurosurgery training programs and in the workplace results in a dearth of female role models for the mentoring of residents and junior faculty/practitioners. This lack of guidance contributes to perpetuation of barriers to women considering careers in neurosurgery, and to the lack of professional advancement experienced by women already in the field. There is ample evidence that mentors and role models play a critical role in the training and retention of women faculty within academic medicine. The absence of a critical mass of female neurosurgeons in academic medicine may serve as a deterrent to female medical students deciding whether or not to pursue careers in neurosurgery. There is limited exposure to neurosurgery during medical school. Medical students have concerns regarding gender inequities (acceptance into residency, salaries, promotion, and achieving leadership positions). Gender inequity in academic medicine is not unique to neurosurgery; nonetheless, promotion to full professor, to neurosurgery department chair, or to a national leadership position is exceedingly rare within neurosurgery. Bright, competent, committed female neurosurgeons exist in the workforce, yet they are not being promoted in numbers comparable to their male counterparts. No female neurosurgeon has ever been president of the AANS, Congress of Neurological Surgeons, or Society of Neurological Surgeons (SNS), or chair of the American Board of Neurological Surgery (ABNS). No female neurosurgeon has even been on the ABNS or the Neurological Surgery Residency Review Committee and, until this year, no more than 2 women have simultaneously been members of the SNS. Gender inequity serves as a barrier to the advancement of women within both academic and community-based neurosurgery. Strategic Approach to Address Issues Identified.: To overcome the issues identified above, the authors recommend that the AANS join WINS in implementing a strategic plan, as follows: 1) Characterize the barriers. 2) Identify and eliminate discriminatory practices in the recruitment of medical students, in the training of residents, and in the hiring and advancement of neurosurgeons. 3) Promote women into leadership positions within organized neurosurgery. 4) Foster the development of female neurosurgeon role models by the training and promotion of competent, enthusiastic, female trainees and surgeons.