Cerebral pan-angiography was repeated in 24 patients with spontaneous subarachnoid hemorrhage confirmed by spinal fluid or computed tomography evidence after the initial pan-angiography was negative. Recent, long-term follow-up was also conducted. The pan-angiography was technically adequate and did not show vasospasm, both being causes of aneurysmal nonvisualization. No etiology was demonstrated on repeat study in all 24 patients. An additional three patients had only one study, but autopsy later confirmed lack of etiology for subarachnoid hemorrhage despite gross and microscopic serial sections. The mean duration of follow-up was 18.1 years and outcome was favorable. Our results suggest that repeat cerebral pan-angiography may not be indicated in the patient who has no further bleeding episodes and in whom the initial study was normal, technically adequate, and complete without evidence of vasospasm. Nonvisualization of a cerebral aneurysm is commonly proposed as the most likely cause of subarachnoid hemorrhage when angiography is normal following nontraumatic subarachnoid hemorrhage. Our results suggest this conclusion is no longer accurate if the angiogram is technically adequate with the absence of vasospasm.

Cerebral Angiography↗

PubMed1990

Culturing cells in a mechanically active environment.

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Animals↗

PubMed1989

Hematocrit monitor.

The purpose of this study is to determine experimentally the optimal incident visible wavelength and light detector angle that yields the maximal change in optical density between an arterial or venous Hct of 20% and 40%. A universal monochromator allows incident wave-lengths in 8-nm increments over the visible range to be selected for the incident beam and a motorized shuttle allows the two samples (Hct 20% and 40%) to be placed reproducibly between the incident beam and photodiode detector. Runs performed with the light detector at a 30 degree, 90 degree, and 180 degree angle from the incident light beam revealed the greatest change in optical density between an Hct of 20% and 40% to occur at 624 nm and 90 degrees independent of sample cell configuration, light source profile, or light detector profile. This experimentally determined optimal wavelength and angle are utilized in a fiberoptic biosensor to monitor Hct successfully in dogs undergoing surgical procedures.

Animals↗

PubMed1974