Experimental effects of steroids and steroid withdrawal on cerebrospinal fluid absorption.

The authors studied the effects on cerebrospinal fluid (CSF) absorption of chronic administration and acute withdrawal of steroids in dogs. CSF absorption was measured by determining the amount of isotope (indium 111DTPA) recovered over a 4-hour period after injection into the cisterna magna. Resistance to CSF absorption was estimated by determining rates of low of Ringer's lactate infusion into the cisterna magna over a range of pressure gradients between CSF and sagittal sinus. Steroid withdrawal was associated with a marked reduction in CSF absorption and an increase in resistance to CSF flow. Dogs on steroids also showed reduced CSF absorption although the reduction was not statistically significant when compared with controls. The results are discussed in terms of possible mechanisms of action of steroids on CSF absorption, the etiology of the benign intracranial hypertension syndrome and the use of steroids and in the control of intracranial hypertension.