抄録
Flow rates and flow patterns of cerebrospinal fluid shunts were evaluated in 55 cases of normally functioning shunts (Rickham-Holter shunts: 20, Pudenz shunts: 35). After approximately 0.05 ml of 100μ Ci of 99mTcpertechnetate was injected into a reservoir, the radioactivity clearance half-time (T1/2) was determined. Then, a flow rate (F ml/min) was calculated according to the formula established in the previous studies: log10 (F) = -1.8 log10 (T1/2) +0.019 in the standard Rickham reservoir and logo (F)= -1.3 log10 (T1/2)+0.087 in the Pudenz 12 mm reservoir. From the 109 observations evaluating flow rates and their patterns it became apparent that CSF flow through the implanted shunts was not continuous but rather sporadic, depending upon the patient's posture and the intraventricular pressure. The difference in the shunt devices showed no influence at all. In sitting positions flow rates of more than 0.1 ml/min were usually observed, whereas in supine positions flow rates ranged from 1.0 ml/min to 0.01 ml/min or below. When flow rates were determined sequentially in both sitting and supine positions, those in the sitting position were higher than those in the supine positions in 96%, and furthermore, in 33% the lowest flow rates were in the supine position. Flow rates and their patterns were found basically consistent in cases reexamined at long intervals of 10 days and 2, 6 and 12 months.
