Effects of Alterations in Posture on the Cerebrospinal Fluid Pressure

Posture-induced Changes in Intracranial Pressure: A Comparative Study in Patients with and without a Cerebrospinal Fluid Block at the Craniovertebral Junction

“…The cause for the ICP increases seen in some patients with a 60°head position may include changes in the intracranial intravascular volume caused by autoregulatory attempts to maintain cerebral blood flow in the presence of failing systemic blood pressure and in a situation of reduced craniospinal compliance. An additional argument against excessively raising the bed's upper back support in neurocritical patients is the possibility of increasing intra-abdominal pressure caused by contraction of the abdominal wall and of producing secondary increases in venous pressure and ICP (16). Although some authors propose that the optimal head position should be established in each patient (31), there is general agreement that the optimal position is between 15°and 30°(8).…”

“…I ntracranial pressure (ICP) reduction with even slightly negative values is a wellknown physiological phenomenon demonstrated in humans in pivotal clinical studies (16,18,19). Among other factors, head elevation decreases ICP by displacing cerebrospinal fluid (CSF) into the spinal canal and by improving cerebral venous drainage by opening alternative venous channels in the posterior circulation that remain closed while patients remain recumbent (16,19,36).…”

“…Among other factors, head elevation decreases ICP by displacing cerebrospinal fluid (CSF) into the spinal canal and by improving cerebral venous drainage by opening alternative venous channels in the posterior circulation that remain closed while patients remain recumbent (16,19,36). Under normal circumstances, when a supine subject sits or stands up, ICP falls to subatmospheric values (16). ICP reductions after changes in body position may also occur in patients with high ICP (8).…”

The Estimation of the Time Constant of the Human Inner Ear Pressure Change by Noninvasive Technique

“…Superimposed on the baseline ICP are periodic changes due to cardiovascular activity and respiration [4,10,11]. In addition, the ICP varies with the posture change [12,13]. To achieve a new equilibrium state between the hydrodynamical interactions, a variation of the flow resistance (R A ) of the cochlear aqueduct has been linked to the perpetual state of flux [2,14,15].…”

Spinal flexion and CSF pressure

“…With these results they conclude that epidural puncture performed in a fully flexed position may increase the incidence of inadvertent dural puncture. However, when moving from lateral to the sitting position, the mean CSF pressure increases by 28 mmHg [1]. Yet with this greatly increased CSF pressure, there is no evidence that epidural puncture performed in the sitting position carries a greater risk of inadvertent dural puncture.…”