✓ The authors tested the hypothesis that cerebral blood flow (CBF) reactivity to CO2 was blunted following subarachnoid hemorrhage (SAH). Subarachnoid hemorrhage was produced in five cats by performing four cisterna magna injections of blood in each (SAH Group). A second group of six cats was treated with an antifibrinolytic agent (AF) in addition to four cisterna magna blood injections (SAH + AF Group). Four cats received AF and four cisterna magna injections of saline (Control Group). The presence or absence of basilar artery vasospasm was determined by comparing baseline and follow-up selective angiograms. Cerebral blood flow reactivity was determined by randomly varying the concentration of inspired CO2 to alter PaCO2 from 20 to 75 mm Hg. Regional CBF was measured with radiolabeled microspheres. Basilar artery vasospasm was seen following subarachnoid injection of blood but not of saline. Normocapnic CBF was similar in all three groups in the brain stem (mean ± standard error of the mean: SAH Group 46 ± 6, SAH + AF Group 46 ± 6, and Control Group 44 ± 9 ml/min/100 gm) and in the supratentorial compartment (SAH Group 53 ± 8, SAH + AF Group 61 ±9, and Control Group 51 ± 13 ml/min/100 gm). At intermediate levels of hypercarbia (PaCO2 50 ± 3 mm Hg), CBF increased similarly in all three groups (SAH Group 161% ± 32%, SAH + AF Group 118% ± 33%, and Control Group 174% ± 19% compared to baseline); at higher levels of PaCO2 (60 ± 3 mm Hg), CBF values were SAH Group 265% ± 50%, SAH + AF Group 205% ± 47%, and Control Group 159% ± 30% of baseline. At the highest level of PaCO2 (75 ± 6 mm Hg), supratentorial CBF did not increase as much in the SAH + AF Group as in the Control Group (179% ± 59% vs. 463% ± 58% of baseline, respectively). The authors conclude that, in this model of SAH, there is no change in normocapnic CBF; however, blood flow reactivity to hypercarbia is blunted. It is possible that this may result from a combination of narrowing of proximal large vessels and globally impaired reactivity of small vessels.
Michael N. Diringer, Jeffrey R. Kirsch, Daniel F. Hanley and Richard J. Traystman
Timothy J. Yee, Brandon W. Smith, Jacob R. Joseph, Yamaan S. Saadeh, Jay K. Nathan, Elyne N. Kahn, Siri S. Khalsa, Kelsey J. Fearer, Michael J. Kirsch, David R. Nerenz, Victor Chang, Jason M. Schwalb, Muwaffak M. Abdulhak and Paul Park
The Oswestry Disability Index (ODI) is one of the most commonly used patient-reported outcome instruments, but completion of this 10-question survey can be cumbersome. Tools from the Patient-Reported Outcomes Measurement Information System (PROMIS) are an alternative, and potentially more efficient, means of assessing physical, mental, and social outcomes in spine surgery. Authors of this retrospective study assessed whether scores on the 4-item surveys of function and pain from the PROMIS initiative correlate with those on the ODI in lumbar spine surgery.
Patients evaluated in the adult neurosurgery spine clinic at a single institution completed the ODI, PROMIS Short Form v2.0 Physical Function 4a (PROMIS PF), and PROMIS Short Form v1.0 Pain Interference 4a (PROMIS PI) at various time points in their care. Score data were retrospectively analyzed using linear regressions with calculation of the Pearson correlation coefficient.
Three hundred forty-three sets of surveys (ODI, PROMIS PF, and PROMIS PI) were obtained from patients across initial visits (n = 147), 3-month follow-ups (n = 107), 12-month follow-ups (n = 52), and 24-month follow-ups (n = 37). ODI scores strongly correlated with PROMIS PF t-scores at baseline (r = −0.72, p < 0.0001), 3 months (r = −0.79, p < 0.0001), 12 months (r = −0.85, p < 0.0001), and 24 months (r = −0.89, p < 0.0001). ODI scores also correlated strongly with PROMIS PI t-scores at baseline (r = 0.71, p < 0.0001), at 3 months (r = 0.82, p < 0.0001), at 12 months (r = 0.86, p < 0.0001), and at 24 months (r = 0.88, p < 0.0001). Changes in ODI scores moderately correlated with changes in PROMIS PF t-scores (r = −0.68, p = 0.0003) and changes in PROMIS PI t-scores (r = 0.57, p = 0.0047) at 3 months postoperatively.
A strong correlation was found between the ODI and the 4-item PROMIS PF/PI at isolated time points for patients undergoing lumbar spine surgery. Large cohort studies are needed to determine longitudinal accuracy and precision and to assess possible benefits of time savings and improved rates of survey completion.