Postoperative intracerebral haemorrhages remote from the site of the initial operation

The cerebral venous system and the postural regulation of intracranial pressure: implications in the management of patients with cerebrospinal fluid diversion

Loss of cerebrospinal fluid (CSF) occurs commonly in daily neurosurgical practice. Understanding the altered physiology following CSF loss is important for optimization of patient care and avoidance of complications. There is overwhelming evidence now that the cerebral venous system plays a major role in intracranial pressure (ICP) dynamics especially when one takes into account the effects of postural changes, atmospheric pressure, and gravity on the craniospinal axis as a whole. The CSF and cerebral venous compartments are tightly coupled in two important ways. CSF is resorbed into the venous system, and there is also an evolved mechanism that prevents overdrainage of venous blood with upright positioning known as the Starling resistor. With loss of CSF pressure, this protective mechanism could become nonfunctional which may result in posture-related venous overdrainage through the cranial venous outflow tracts leading to pathologic states. This review article summarizes the relevant anatomic and physiologic basis of the relationship between the craniospinal venous and CSF compartments in the setting of CSF diversion. It is hoped that this article improves our understanding of ICP dynamics after CSF loss, adds a new dimension to our therapeutic methods, stimulates further research into this field, and ultimately improves our care of these patients.

Cerebrospinal fluid outflow resistance measurements in the selection of patients for shunt surgery in the normal pressure hydrocephalus syndrome. A controlled trial

In an attempt to determine to what extent the measurement of cerebrospinal fluid (CSF) outflow resistance (R(out)) can distinguish patients with normal-pressure hydrocephalus (NPH) who respond to shunt surgery from patients who fail to do so, the authors undertook a controlled trial. Eighteen patients with the diagnosis of NPH entered the study. In connection with the shunt operation all patients who entered the study underwent R(out) measurement by means of the pressure-volume index (PVI) method of bolus manipulation (Marmarou et al.). As a safety measure patients above 70 of age and patients with dementia as the only clinical symptom underwent continuous intraventricular pressure measurement before they entered the final study. As a result a total of fourteen patients underwent PVI test and shunt surgery during the same procedure. Patients with normal R(out) thus served as controls, since all patients underwent shunt surgery irrespective of the result of the R(out) measurement. Eight patients improved following surgery and the outcome did not correlate with result of PVI nor R(out) determinations.