Jones H C, Lopman B A
Department of Pharmacology and Therapeutics, University of Florida, Gainesville 32610, USA.
Eur J Pediatr Surg. 1998 Dec;8 Suppl 1:55-8. doi: 10.1055/s-2008-1071256.
The relation between increased cerebrospinal fluid (CSF) pressure and ventricular enlargement in infantile hydrocephalus is uncertain, variable, and probably dependent on the etiology of the condition. The HTx rat has early-onset hydrocephalus due to aqueduct stenosis in late gestation with ventricular dilatation present in fetuses. Increased CSF pressure, however, is first detected at postnatal day 10 or later. How the transition from low pressure to raised pressure hydrocephalus takes place, is not clear. In order to study this, we investigated how CSF pressure is related to the magnitude of ventricular dilatation using hydrocephalic and control HTx rats at postnatal days 15 and 21. At 15 days, the CSF pressure for hydrocephalics was 31.1 +/- 3.6 mm H2O (mean +/- SEM) which was not significantly higher than the controls at 19.9 +/- 2.8 mm H2O. At 21 days, the pressure was significantly higher in hydrocephalics at 50.9 +/- 7.5 mm H2O compared to 24.3 +/- 3.6 mm H2O for controls, p < 0.05. The mean volume of the lateral ventricles was 409.3 mm3 at day 15 and 478.8 mm3 at day 21, whereas age-matched control rats in a previous study had ventricles of 14 and 25 mm3. At each age there was a significant linear relationship between CSF pressure and ventricle volume, p < 0.05 at day 15 and p < 0.01 at day 21. Closer examination of the data, however, showed that 5/10 hydrocephalics at day 15 and 4/10 at day 21 had CSF pressures that were within the 95% confidence limits of the mean pressures for the control groups. The ventricle volumes of these low pressure hydrocephalics were between 100 and 280 mm3 which was several times larger than the ventricles in control rats. CSF pressure in the remaining 15 day rats ranged from 30 to 53 mm H2O and in the 21 day rats from 46 to 90 mm H2O and the ventricles were between 280 and 1050 mm3. The results suggest that up to a critical volume the infant rat brain can accommodate additional CSF without an increase in pressure. At this volume there is a "break point" beyond which additional fluid results in further expansion along with an increase in CSF pressure.
婴儿脑积水时脑脊液（CSF）压力升高与脑室扩大之间的关系尚不确定、存在变数，且可能取决于该病的病因。HTx大鼠由于妊娠晚期中脑导水管狭窄而患有早发性脑积水，胎儿期即出现脑室扩张。然而，CSF压力升高最早在出生后第10天或更晚才被检测到。从低压性脑积水向高压性脑积水的转变过程尚不清楚。为了研究这一问题，我们在出生后第15天和第21天，使用脑积水HTx大鼠和对照HTx大鼠，研究了CSF压力与脑室扩张程度之间的关系。在15天时，脑积水大鼠的CSF压力为31.1±3.6 mmH₂O（均值±标准误），显著高于对照组的19.9±2.8 mmH₂O。在21天时，脑积水大鼠的压力显著升高，为50.9±7.5 mmH₂O，而对照组为24.3±3.6 mmH₂O，p<0.05。侧脑室的平均体积在15天时为409.3 mm³，在21天时为478.8 mm³，而在之前一项研究中，年龄匹配的对照大鼠脑室体积为14和25 mm³。在每个年龄段，CSF压力与脑室体积之间均存在显著的线性关系，15天时p<0.05，21天时p<0.01。然而，对数据的进一步检查显示，15天时10只脑积水大鼠中有5只，21天时10只中有4只的CSF压力在对照组平均压力的95%置信区间内。这些低压性脑积水大鼠的脑室体积在100至280 mm³之间，比对照大鼠的脑室大几倍。其余15日龄大鼠的CSF压力范围为30至53 mmH₂O，21日龄大鼠为46至90 mmH₂O，脑室体积在280至1050 mm³之间。结果表明，在达到临界体积之前，幼鼠大脑可以容纳额外的CSF而不导致压力升高。在这个体积时存在一个“转折点”，超过该点后，额外的液体将导致脑室进一步扩张并伴有CSF压力升高。
