cerebrospinal fluid pressure

Changes of cerebrospinal fluid pressure after thoracic endovascular aortic repair

Authors: Xue L, Luo JF, Liu Y, Huang WH, Ni ZH, He PC, Xie NJ, Fan RX, Luo SY, Chen JY.

BACKGROUND: Decreasing the intracranial pressure has been advocated as one of the major protective strategies to prevent spinal cord ischemia after endovascular aortic repair. However, the actual changes of cerebrospinal fluid (CSF) pressure and its relation with spinal cord ischemia have been poorly understood. We performed CSF pressure measurements and provisional CSF withdrawal after thoracic endovascular aortic repair, and compared the changes of CSF pressure in high risk patients and in patients with new onset paraplegia and paraparesis.
METHODS: Four hundred and nineteen patients were evaluated for the risk of spinal cord ischemia after thoracic endovascular aortic repair. Patients with identified risk factors before the procedure constituted group H and received prophylactic sequential CSF pressure measurement and CSF withdrawal. Patients who actually developed spinal cord ischemia constituted group P and received rescue CSF pressure measurements and CSF withdrawal.
RESULTS: Among the 419 patients evaluated, 17 were graded as high risk. Four patients actually developed spinal cord ischemia after endovascular repair. The incidence of spinal cord ischemia in this investigation was 0.9%. The patients who actually developed spinal cord ischemia had no identified risk factors and had elevated CSF pressure, ranging from 15.4 to 30.0 mmHg. Six of the 17 patients graded as high risk had elevated CSF pressure: >20 mmHg in two patients and >15 mmHg in four patients. Sequential CSF pressure measurements and provisional withdrawal successfully decrease CSF pressure and prevented symptomatic spinal cord ischemia in high-risk patients. However, these measurements could only successfully reverse the neurologic deficit in two of the patients who actually developed spinal cord ischemia.
CONCLUSIONS: Cerebrospinal fluid pressure was elevated in patients with spinal cord ischemia after thoracic endovascular aortic repair. Sequential measurements of CSF pressure and provisional withdrawal of CSF decreased CSF pressure effectively in high risk patients and provided effective prevention of spinal cord ischemia. Risk factor identification and prophylactic measurements play the key role in prevention of spinal cord ischemia after thoracic endovascular aortic repair.

The role of cerebrospinal fluid pressure in glaucoma and other ophthalmic diseases: A review

Authors: Fleischman D, Allingham RR.

Glaucoma is one of the most common causes of blindness in the world. Well-known risk factors include age, race, a positive family history and elevated intraocular pressures. A newly proposed risk factor is decreased cerebrospinal fluid pressure (CSFP). This concept is based on the notion that a pressure differential exists across the lamina cribrosa, which separates the intraocular space from the subarachnoid fluid space. In this construct, an increased translaminar pressure difference will occur with a relative increase in elevated intraocular pressure or a reduction in CSFP. This net change in pressure is proposed to act on the tissues within the optic nerve head, potentially contributing to glaucomatous optic neuropathy. Similarly, patients with ocular hypertension who have elevated CSFPs, would enjoy a relatively protective effect from glaucomatous damage. This review will focus on the current literature pertaining to the role of CSFP in glaucoma. Additionally, the authors examine the relationship between glaucoma and other known CSFP-related ophthalmic disorders.

Valsalva manoeuver, intra-ocular pressure, cerebrospinal fluid pressure, optic disc topography: Beijing intracranial and intra-ocular pressure study

Authors: Zhang Z, Wang X, Jonas JB, Wang H, Zhang X, Peng X, Ritch R, Tian G, Yang D, Li L, Li J, Wang N.

PURPOSE: To assess whether a Valsalva manoeuver influences intra-ocular pressure (IOP), cerebrospinal fluid pressure (CSF-P) and, by a change in the trans-laminar cribrosa pressure difference, optic nerve head morphology.
METHODS: In the first part of the study, 20 neurological patients (study group 'A') underwent measurement of IOP and lumbar CSF-P measurement in a lying position before and during a Valsalva manoeuver. In the second study part, 20 healthy subjects (study group 'B') underwent ocular tonometry and confocal scanning laser tomography of the optic nerve head before and during a Valsalva manoeuver.
RESULTS: During the Valsalva manoeuver in study group 'A', the increase in CSF-P by 10.5 ± 2.7 mmHg was significantly (p < 0.001) higher than the increase in IOP by 1.9 ± 2.4 mmHg. The change in CSF-P was not significantly (p = 0.61) correlated with the change in IOP. During the Valsalva manoeuver in study group 'B', IOP increased by 4.5 ± 4.2 mmHg and optic cup volume (p < 0.001), cup/disc area ratio (p = 0.02), cup/disc diameter ratio (p = 0.03) and maximum optic cup depth (p = 0.01) significantly decreased, while neuroretinal rim volume (p = 0.005) and mean retinal nerve fibre layer thickness (p = 0.02) significantly increased.
CONCLUSIONS: The Valsalva manoeuver-associated short-term increase in CSF-P was significantly larger than a simultaneous short-term increase in IOP. It led to a Valsalva manoeuver-associated decrease or reversal of the trans-laminar cribrosa pressure difference, which was associated with a change in the three-dimensional optic nerve head morphology: optic cup-related parameters decreased and neuroretinal rim-related parameters enlarged. These findings may be of interest for the pathogenesis of glaucomatous optic neuropathy.

Central venous pulsations: new findings, clinical importance and relation to cerebrospinal fluid pressure

Authors: Morgan WH.

The translaminar pressure gradient (TLPG) is largely influenced by the difference between intraocular pressure (IOP) and cerebrospinal fluid pressure (CSFP), but modulated by the buffering effect of orbital tissue and pia mater, which limits the reduction in retrolaminar tissue pressure as intracranial CSFP falls below 0 mm Hg. Across the lamina cribrosa, the central retinal vein experiences the greatest pressure gradient (TLPG) of any vein in the body. When CSFP rises, the minimum IOP required to induce venous pulsation pressure (VPP) rises with CSFP (r=0.95, slope=0.90). Lowering IOP in glaucoma patients leads to a reduction in VPP (P=0.0003). The normal human central retinal vein endothelial cells in the lamina region resemble typical arterial endothelia and are quite unlike other venous cells. It is likely that the TLPG is increasing retinal vein shear and in glaucoma this effect is likely to be increased with possible wall effects.

How to measure cerebrospinal fluid pressure invasively and noninvasively

Authors: Silverman CA, Linstrom CJ.

We describe tympanic membrane displacement (TMD) testing for non-invasive estimation of intracranial pressure (ICP). With the TMD test, displacement of the tympanic membrane of the middle ear is recorded during elicitation of the acoustic middle-ear reflex (AR). Increased intracranial/perilymphatic pressure displaces the resting stapes footplate laterally so that TMD during the acoustic reflex is medial. Decreased intracranial/perilymphatic pressure displaces the baseline stapes footplate position medially (inward) so that TMD during the AR is lateral. The TMD typically is bidirectional when intracranial/perilymphatic pressure is normal. Discrepant findings have been reported for the sensitivity of the TMD test to ICP as the regression of TMD on invasive measurement of the ICP reveals substantial intersubject variability and overlap among patient and control groups. Large-sample research on TMD test performance in healthy persons and patients with various disorders affecting the ICP is needed using direct, invasive measures of the ICP as the gold standard. Research also is needed to examine whether non-invasive TMD testing can be used to investigate the trans-lamina cribrosa pressure difference in glaucoma.

Idiopathic intracranial hypertension: A caesarean with epidural anaesthesia after bringing the cerebrospinal fluid pressure back to normal

Authors: Pérez Rodríguez M, de Carlos Errea J, Dorronsoro Auzmendi M, Batllori Gastón M.

Idiopathic intracranial hypertension is diagnosed by exclusion. Because of its uncertain physiopathology and infrequent occurrence, its anaesthetic management is not well defined. The patient in this case is a pregnant woman with this disease with no lumbar-peritoneal shunt who was referred for non-urgent caesarean section, consisting of CSF drainage and pressure normalisation before the administration of epidural anaesthesia. We believe this technique can de effective to achieve adequate blockage and increased patient comfort, as well as improving postoperative recovery.

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