Effect of intra-arterial papaverine on regional cerebral blood flow in hemodynamically relevant cerebral vasospasm

Background and Purpose-It remains controversial whether the intra-arterial administration of papaverine (IAP) is effective in reversing vasospasm-asso ciated cerebral hypoperfusion after aneurysmal subarachnoid hemorrhage, The aim of the present study was to continuously assess regional cerebral bloo d flow (rCBF) during and after IAP with the use of quantitative, bedside th ermal diffusion flowmetry. Methods-Eight patients with cerebral vasospasm after subarachnoid hemorrhag e (mean flow velocity >120 cm/s; angiographic vessel constriction >33%; hem ispheric cerebral blood Row [CBF] <32 mL/100 g per minute) were prospective ly entered into the study. Before IAP, thermal diffusion microprobes were i mplanted into the white matter of each affected vascular territory (n = 10) for rCBF monitoring. During and after IAP (300 mg papaverine/50 mt Saline over 1 hour), mean arterial blood pressure, intracranial pressure, cerebral perfusion pressure, thermal diffusion rCBF (TD-rCBF), and cerebrovascular resistance (CVR) were recorded continuously. Results-IAP significantly increased TD-rCBF from 7.3 +/- 1.6 to 37.9 +/- 6. 6 mL/100 g per minute (mean a SEM), indicating reversal of cerebral hypoper fusion. This TD-rCBF response was dependent on the degree of cerebral vasos pasm and reduced perfusion within the vascular territory. Long-term analysi s of TD-rCBF, however, demonstrated that this beneficial effect of IAP on c erebral hypoperfusion was only transient: within 3 hours after treatment, T D-rCBF and CVR returned to baseline values. Furthermore, a lack of correlat ion between transcranial Doppler sonography and thermal diffusion flowmetry suggested that transcranial Doppler sonography is not suited for CBF-based neuromonitoring after IAP. Conclusions-IAP is not effective in permanently reversing cerebral hypoperf usion in patients with cerebral vasospasm. The need to validate alternative therapeutic strategies that seek to improve cerebral perfusion in vasospas m warrants continued development of CBF-based neuromonitoring strategies.