Intracranial pressure (ICP) pulsations are generally considered a passive result of the pulsatility of blood flow. Active experimental modification of ICP pulsations would allow investigation of potential active effects on blood and CSF flow and potentially create a new platform for the treatment of acute and chronic low blood flow states as well as a method of CSF substance clearance and delivery. This study presents a novel method and device for altering the ICP waveform via cardiac-gated volume changes.
The novel device used in this experiment (named Cadence) consists of a small air-filled inelastic balloon (approximately 1.0 ml) implanted into the intracranial space and connected to an external programmable pump, triggered by an R-wave detector. Balloons were implanted into the epidural space above 1 of the hemispheres of 19 canines for up to 10 hours. When activated, the balloons were programed to cyclically inflate with the cardiac cycle with variable delay, phase, and volume. The ICP response was measured in both hemispheres. Additionally, cerebral blood flow (heat diffusion and laser Doppler) was studied in 16 canines.
This system, depending on the inflation pattern of the balloon, allowed a flattening of the ICP waveform, increase in the ICP waveform amplitude, or phase shift of the wave. This occurred with small mean ICP changes, typically around ± 2 mm Hg (15%). Bilateral ICP effects were observed with activation of the device: balloon inflation at each systole increased the systolic ICP pulse (up to 16 mm Hg, 1200%) and deflation at systole decreased or even inverted the systolic ICP pulse (−0.5 to −19 mm Hg, −5% to −1600%) in a dose-(balloon volume) dependent fashion. No aphysiological or deleterious effects on systemic pressure (≤ ±10 mm Hg; 13% change in mean pressure) or cardiac rate (≤ ± 17 beats per minute; 16% change) were observed during up to 4 hours of balloon activity.
The results of these initial studies using an intracranially implanted, cardiac-gated, volume-oscillating balloon suggest the Cadence device can be used to modify ICP pulsations, without physiologically deleterious effects on mean ICP, systemic vascular effects, or brain injury. This device and technique may be used to study the role of ICP pulsatility in intracranial hemo- and hydrodynamic processes and introduces the creation of a potential platform of a cardiac-gated system for treatment of acute and chronic low blood flow states, and diseases requiring augmentation of CSF substance clearance or delivery.
ABBREVIATIONSΔBV = (theoretical) amplitude of the balloon volume variation; ABP = arterial blood pressure; A/D = analog to digital translating; CBF = cerebral blood flow; CBFLD = CBF laser Doppler; CBFTD = CBF thermal diffusion; CBFV = CBF velocity; EKG = electrocardiogram; ICP = intracranial pressure; TPU = tissue perfusion unit.
INCLUDE WHEN CITING Published online July 15, 2016; DOI: 10.3171/2016.4.JNS152457.Correspondence Mark G. Luciano, Department of Neurosurgery, Johns Hopkins, 600 North Wolfe St., Phipps 126, Baltimore, MD 20287. email: email@example.com.Disclosures Drs. Luciano and Dombrowski are listed as inventors on 2 patents regarding the device presented in this paper. This study received contractual research support from CSF Therapeutics Inc.
BilstonLEStoodleyMAFletcherDF: The influence of the relative timing of arterial and subarachnoid space pulse waves on spinal perivascular cerebrospinal fluid flow as a possible factor in syrinx development. J Neurosurg112:808–8132010
BilstonLE, StoodleyMA, FletcherDF: The influence of the relative timing of arterial and subarachnoid space pulse waves on spinal perivascular cerebrospinal fluid flow as a possible factor in syrinx development. 112:808–813, 20101952257410.3171/2009.5.JNS08945)| false
Di RoccoCPettorossiVECaldarelliMMancinelliRVelardiF: Communicating hydrocephalus induced by mechanically increased amplitude of the intraventricular cerebrospinal fluid pressure: experimental studies. Exp Neurol59:40–521978
GreitzDWirestamRFranckANordellBThomsenCStåhlbergF: Pulsatile brain movement and associated hydrodynamics studied by magnetic resonance phase imaging. The Monro-Kellie doctrine revisited. Neuroradiology34:370–3801992
GreitzD, WirestamR, FranckA, NordellB, ThomsenC, StåhlbergF: Pulsatile brain movement and associated hydrodynamics studied by magnetic resonance phase imaging. The Monro-Kellie doctrine revisited. 34:370–380, 1992140751310.1007/BF00596493)| false
JiB, ÜndarA: An evaluation of the benefits of pulsatile versus nonpulsatile perfusion during cardiopulmonary bypass procedures in pediatric and adult cardiac patients. 52:357–361, 20061688311210.1097/01.mat.0000225266.80021.9b)| false
KellieG: An account of the appearances observed in the dissection of two of three individuals presumed to have perished in the storm of the 3d, and whose bodies were discovered in the vicinity of Leith on the morning of the 4th, November 1821; with some reflection. Trans Med Chir Soc Edinburgh1:84–1691824
KellieG: An account of the appearances observed in the dissection of two of three individuals presumed to have perished in the storm of the 3d, and whose bodies were discovered in the vicinity of Leith on the morning of the 4th, November 1821; with some reflection. 1:84–169, 1824)| false
MitchellGF: Effects of central arterial aging on the structure and function of the peripheral vasculature: implications for end-organ damage. 105:1652–1660, 20081877232210.1152/japplphysiol.90549.2008)| false
OldfieldEHMuraszkoKShawkerTHPatronasNJ: Pathophysiology of syringomyelia associated with Chiari I malformation of the cerebellar tonsils. Implications for diagnosis and treatment. J Neurosurg80:3–151994
OldfieldEH, MuraszkoK, ShawkerTH, PatronasNJ: Pathophysiology of syringomyelia associated with Chiari I malformation of the cerebellar tonsils. Implications for diagnosis and treatment. 80:3–15, 199410.3171/jns.1994.80.1.00038271018)| false
O'RourkeMF, SafarME: Relationship between aortic stiffening and microvascular disease in brain and kidney: cause and logic of therapy. 46:200–204, 200510.1161/01.HYP.0000168052.00426.6515911742)| false