Normal position of the aqueduct of Sylvius. Part 2: evaluation of two preaqueductal proportional methods.
Two new proportional methods for determination of the normal or abnormal position of the cerebral aqueduct are described. The position of the iter is expressed by the quotients (see article) and (see article), when d-aq represents the distance between the upper posterior surface of the dorsum sellae and the dorsal center of the air-filled aqueduct. Ts equals aq is the distance from the tuberculum sellae to the same point, and TW is Twining's line. The normal value of the dorsum to aqueduct ratio was 0.32 plus or minus 0.02 standard deviation (SD) and of the tuberculum to aqueduct ratio 0.44 plus or minus 0.03 SD. Both proportional methods are independent of skull dimensions. These are compared to another proportional method described in Part 1 of this report.
D000293:Adolescent; D000328:Adult; D001933:Brain Stem / Q000033:anatomy & histology; D002508:Cephalometry; D002535:Cerebral Aqueduct / Q000033:anatomy & histology*; D002648:Child; D006801:Humans; D008875:Middle Aged; D011011:Pneumoencephalography; D012658:Sella Turcica / Q000033:anatomy & histology; D012886:Skull / Q000000981:diagnostic imaging