Patent Application
20080249458
The invention relates generally to medical devices and methods for use during surgical procedures. More specifically, the invention is related to methods and apparatus for use in opening an obstruction within the brain.
Hydrocephalus is sometimes referred to as ‘water on the brain’. A watery fluid, known as cerebrospinal fluid or CSF, is produced continuously inside each of the four spaces or ventricles inside the brain. The CSF normally flows through narrow pathways from one ventricle to the next, then out across the outside of the brain and down the spinal cord. The CSF is absorbed into the bloodstream and recirculates. The amount and pressure of CSF in the brain are normally kept within a fairly narrow range. However, if the flow pathways are blocked at any point, the fluid accumulates in the cerebral ventricles and/or subarachnoid space, causing them to swell, which thereby results in an increase on intracranial pressure, and compression of the surrounding tissue. In babies and infants prior to the closure of the cranial sutures, hydrocephalus will cause the head to enlarge. In older children and adults, the head size cannot increase as the bones which form the skull are completely joined together and, as such, hydrocephalus may cause severe headaches, nausea, abnormal gait, dementia and/or permanent brain damage.
Non-communicating or obstructive hydrocephalus due to blood clots or other obstructions that restrict CSF flow within the ventricles or ventricular outlets, such as infectious material or tumors, is primarily treated by ventriculoperitoneal (VP) shunts. A shunt is a drain that diverts or “shunts” the accumulated CSF from the obstructed drainage pathways to another part of the body for absorption. These devices are catheters that are surgically lowered through a hole drilled in the skull and brain to have one end positioned in the lateral ventricle, while the other end of the catheter is tunneled under the skin and positioned in the peritoneal cavity of the abdomen, or right atrium of the heart, where the cerebrospinal fluid is absorbed or drained respectively. The catheter tubing has ports for receiving CSF that often get clogged by cellular in-growth and the catheters also utilize one-way valves or pressure valves. The failure rate for these devices ranges from 30% to 40% due to clogging of the catheter, infection, and/or faulty pressure or one-way valves. The surgical procedure requires burring holes in the skull and passage of the shunt through the cerebral cortex and underlying white matter, which may cause damage to those parts of the brain. VP shunts are also indicated for patients with communicating hydrocephalus, where CSF absorption into the venous system is restricted at the arachnoid granulations.
Recently neuroendoscopy, or telescopic surgery, makes treatment of hydrocephalus in some patients possible without shunting, the success rate depending on the etiology of the hydrocephalus. Management of hydrocephalus by endoscopic third ventriculostomy (ETV) involves creating an opening in the floor of the third ventricle, allowing the CSF to bypass the obstruction. This is a surgical procedure that does not have the complications of shunt insertion, i.e., infection is rare and morbidity is very low. However, ETV is not effective in patients with communicating hydrocephalus. Also, placement of a VP shunt and ETV procedures both require burr holes in the skull and introduction of medical apparatus through the cerebral cortex and underlying white matter.
What is needed are alternative treatment methods and apparatus that provide a less invasive approach to removing hydrocephalus causing obstructions within the brain and/or placing a shunt through the obstructed site to provide drainage of cerebrospinal fluid there through.
Embodiments hereof are directed to an intraventricular shunt for use in treating non-communicating hydrocephalus. The shunt includes a tubular structure having a length that substantially corresponds with a length of an opening in the brain in which the tubular structure is to be implanted, such as a length that corresponds with a length of one of the Foramen of Monro, cerebral aqueduct, Foramina of Magendie or Luschka, an arachnoid cyst, and a length for crossing the septum pellucidum. The tubular structure may be a polymeric cylindrical tube having the same diameter before and after implantation within the brain opening, or may have a fixed deployed diameter. In an embodiment, the shunt may have an hour glass shape or a single flared end in a deployed configuration. In another embodiment, the intraventricular shunt may be a self-expanding stent structure with a fixed expanded diameter.
Embodiments include methods for use within the subarachnoid space of the central nervous system to gain access to and treat an obstruction within the ventricles of the brain or a subarachnoid hemorrhage. A method of treating non-communicating hydrocephalus includes gaining access to the subarachnoid space of the spinal column and navigating an aspiration catheter through the subarachnoid space to the base of the skull. The aspiration catheter is then navigated along the brain in one of the subarachnoid space and ventricles until an obstruction for treatment is reached. A distal tip of the aspiration catheter is positioned proximal to the obstruction to be treated so that the obstruction may be aspirated and removed by the aspiration catheter. The aspiration catheter may be navigated into the fourth ventricle of the brain via one of the foramen of Magendie and the foramina of Luschka and subsequently through the ventricles of the brain until the obstruction is reached.
In another embodiment, a delivery catheter having a deployable intraventricular shunt thereon is navigated through the subarachnoid space to the base of the skull and enters the fourth ventricle of the brain via one of the foramen of Magendie and the foramina of Luschka. Navigation of the delivery catheter continues through the ventricles of the brain until the opening created by the aspirated obstruction is reached, and the distal end of the delivery catheter is positioned through the opening. An intraventricular shunt according to an embodiment hereof is then deployed within the opening and the delivery catheter is removed.
The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. The drawings are not to scale.
Specific embodiments of the present invention are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The terms “distal” and “proximal” are used in the following description with respect to a position or direction relative to the treating clinician. “Distal” or “distally” are a position distant from or in a direction away from the clinician. “Proximal” and “proximally” are a position near or in a direction toward the clinician.
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
Navigation of subarachnoid catheter 206 through subarachnoid space 102 and within the ventricles of the brain may be assisted with a guidewire. The position of the guidewire within the subarachnoid space and ventricles of the brain, as well as that of other medical devices used in accordance with methods herein, may be monitored by using any suitable imaging technology, such as magnetic resonance imaging, fluoroscopy, endoscopy, fiberoptic visualization, computed tomography, thermal imaging, sonography, X-ray visualization, and/or any combination of these. Accordingly, access to the ventricles via a lumbar or cervical puncture by methods according to the present invention significantly reduces recovery time to a day or sooner, instead of several days to weeks as is customary with the more invasive VP procedures currently in practice, which as mentioned may include burr holes through the skull and invasion of the cerebral cortex and subcortical white matter by medical apparatus.
If the non-communicating hydrocephalus is caused by a subarachnoid or intraventricular hemorrhage and clotting, or other obstruction, such as from infectious material, the obstruction may be slowly aspirated through subarachnoid catheter 206 using a controlled aspiration system to prevent excess removal of CSF and slit ventricle or collapsed ventricle situations. Removal of a subarachnoid hemorrhage will also reduce risk of severe vasospasm of the surrounding arteries and other SAH-induced adverse events. Once the obstruction is removed, aspiration or gradual shunting of CSF may continue until the excess cerebrospinal fluid within the ventricle is removed, with care being taken not to drain too quickly, or to remove too much cerebrospinal fluid and causing slit ventricle syndrome. The placement of subarachnoid catheter 206 and removal of cerebrospinal fluid may be monitored by fluoroscopy. A constant volume aspiration catheter as disclosed in provisional application U.S. Appl. No. 60/910,770 filed on Apr. 6, 2007, which is incorporated by reference herein in its entirety, may also be used to inject a fluid to break-up an obstruction while simultaneously aspirating the debris to maintain a constant volume aspiration.
In another embodiment of the present invention shown in
Embodiments of intraventricular shunts according to the present invention are delivered to the treatment site by less invasive procedures than placement of a VP shunt or an ETV procedure making infection less likely. VP shunt valves for pressure relief and the excess catheter length thereof, which is required to accommodate growth in infants and children, are not needed with an intraventricular shunt according to the present invention, as it is sized to be positioned entirely within the treatment site in the brain.
In the embodiment of
In an embodiment, a stent design that minimizes herniation of brain parenchyma through the stent-like struts yet still allows access to and/or drainage of CSF may be beneficial. Stent structures having struts as shown in U.S. Pat. No. 4,733,665 to Palmaz, U.S. Pat. No. 4,800,882 to Gianturco, U.S. Pat. No. 4,886,062 to Wiktor, U.S. Pat. No. 5,133,732 to Wiktor, U.S. Pat. No. 5,292,331 to Boneau, U.S. Pat. No. 5,421,955 to Lau, U.S. Pat. No. 5,776,161 to Globerman, U.S. Pat. No. 5,935,162 to Dang, U.S. Pat. No. 6,090,127 to Globerman, U.S. Pat. No. 6,113,627 to Jang, U.S. Pat. No. 6,663,661 to Boneau and U.S. Pat. No. 6,730,116 to Wolinsky et al., each of which is incorporated by reference herein in its entirety, may be adapted for use in embodiments of the present invention.
In another embodiment shown in
In another embodiment shown in
In another embodiment, a tubular shunt hereof may be a braided structure of a constant diameter, such as the embodiment of
In another embodiment shown in
In another embodiment shown in
Alternatively, as shown in a side view of tubular shunt 810 in
In an alternate embodiment, a tubular shunt in accordance herewith may include expandable proximal and distal segments, structurally similar to ends 611, 613 or 811 of the previous embodiments, that attach to each other at their non-flared ends without a constant diameter segment, such as midsection 617, therebetween.
Methods of delivery of shunts according to embodiments of the present invention will now be discussed with reference to the embodiment shown in
Polymeric tubular structure 415 may be made of one or more suitable polymeric materials, including a thermoplastic material, such as polyethylene block amide copolymer, polyvinyl chloride, polyethylene, polyethylene terephthalate, polyamide, polyurethane and/or a thermoset polymer, such as polyimide. In another embodiment of the present invention, tubular structure 415 may also be made of a resorbable polymeric materials, such as PLA (polylactic acid), polycaprolactone, copolymers of lactic acid, glycolic acid, caprolactone, trimethylene carbonate, dioxanone in any permutation and combinations thereof.
An intraventricular shunt according to embodiments of the present invention may be of varying diameters and lengths depending on the delivery site within the brain, i.e., whether the shunt will be delivered to or within the Foramen of Monro, 3rd ventricle, cerebral aqueduct, 4th ventricle, Foramina of Magendie or Luschka, arachnoid cyst, or across the septum pellucidum. In an exemplary embodiment, polymeric tubular structure 415 of intraventricular shunt 410 may be between 0.5 mm to 5 mm in diameter and up to 2 cm in length. More particularly, shunt 410 may be a length of between 2 mm and 4 mm to bridge the foramen of Monro or a length of between 10 mm and 16 mm to bridge the cerebral aqueduct.
Subarachnoid shunt delivery catheter may be tracked to the treatment site via a guidewire that has been previously positioned within the subarachnoid space to and beyond the obstruction. In certain medical applications, another subarachnoid catheter may already be in-dwelling, such that the guidewire may be tracked through the lumen of the in-dwelling subarachnoid catheter to and through the obstruction with the subarachnoid catheter being subsequently removed. Shunt delivery catheter may then be tracked along the guidewire up to the obstruction, with the guidewire being subsequently removed.
Subarachnoid delivery catheters for delivering intraventricular shunts in accordance with various embodiments of the present invention may be approximately 150 cm in length. A distal tip of a delivery catheter in accordance with various embodiments may include a rounded edge to minimize the likelihood of catching or tearing vessels, spinal nerve rootlets and central nervous system tissue as it is tracked to the cite of the obstruction within the brain ventricles. The distal tip of the delivery catheter may also include a radiopaque marker to facilitate accurate positioning of the catheter and the intraventricular shunt by fluoroscopy. In various embodiments, a distal portion of the delivery catheter may have a diameter ranging from 2 F to 9 F depending on the application in which it is to be used.
In a method according to an embodiment of the present invention, a clinician determines that a lumbar puncture may be performed without the risk of cerebral herniation. If cerebral herniation is of risk, burr holes can be made in the skull with a catheter placed in the adjacent subarachnoid space to relieve excess intracranial pressure. The lumbar puncture is performed with a catheter introducer, or another appropriate medical instrument, and a Touhy Borst valve is attached. An aspiration catheter is inserted through the Touhy Borst valve and catheter introducer to thereby gain access to the spinal subarachnoid space. The aspiration catheter is then navigated superiorly within the spinal subarachnoid space to the base of the skull. The aspiration catheter may then make entry into the fourth ventricle through the foramen of Magendie, one of the foramina of Luschka or navigated to the site of subarachnoid hemorrhage over the brain surfaces, i.e., cisterns at the skull base. The aspiration catheter is then tracked within the ventricles or subarachnoid space until the distal tip is positioned proximal to the obstruction. Radiopaque markers and/or fiber optic imaging may be used to aid in positioning of the distal tip of the catheter. Aspiration or attempted aspiration of the obstruction is performed and the aspiration catheter is withdrawn over the wire. If the obstruction cannot be aspirated, or there is a risk of re-occlusion, a shunt delivery catheter is then inserted through the Touhy Borst valve and introducer and navigated through the spinal subarachnoid space and/or ventricles of the brain to the site of the obstruction, as described above with reference to the subarachnoid aspiration catheter. The intraventricular shunt is then positioned across the obstruction using the radiopaque markers or fiberoptic visualization and released from the shunt delivery catheter. Once the shunt delivery catheter is removed, the aspiration catheter may be reintroduced to aspirate excess cerebrospinal fluid, if needed, and/or constant volume aspiration may be performed to clear debris in the CSF at the end of the procedure.
In another embodiment of the present invention, the clot or obstruction may be initially broken up or loosened by an ultrasonic medical device, such as any of the devices disclosed in U.S. Pat. No. 6,660,013 to Rabiner et al. and U.S. Pat. No. 6,652,547 to Rabiner et al., each of which is assigned to OmniSonics Medical Technologies, Inc. of Wilmington, Mass., or by another mechanical disruption provided by, for e.g., sinusoidal wires, coils and the like. The structure of a blood clot caused by subarachnoid or intraventricular hemorrhage may not necessarily form such that the clot is readily susceptible to aspiration. In some cases, blood clotting will occur along the ventricular walls making aspiration difficult. In addition, other types of obstructions that may cause hydrocephalus, such as infectious material and necrotic debris, may be difficult to aspirate without pretreatment. In such presentations where a clot or obstruction cannot be easily removed by aspiration alone, the clot or obstruction may be initially treated, i.e., loosened and/or broken up, through the use of a guidewire that generates ultrasonic waves in the cerebrospinal fluid, such as the ultrasonic medical devices disclosed in the OmniSonics patents mentioned above or by an ultrasound microcatheter such as those available from EKOS Corporation of Bothell, Wash. A method in accordance with an embodiment of the present invention, includes tracking an ultrasonic guidewire to the obstruction within the lumen of an in-place subarachnoid catheter and then activating the guidewire to break up the obstruction while the debris is aspirated through the catheter.
In another embodiment of the present invention, a blood clot may be treated by injecting rt-PA or other thrombolytics into the obstruction via the subarachnoid catheter, followed by aspiration. As previously discussed, the treatment of the blood clot with a constant volume aspiration catheter may be beneficial in improving aspiration efficacy. A constant volume aspiration provides injection of a fluid to break-up the obstruction with simultaneous aspiration of the debris while maintaining a constant volume of CSF.
While various embodiments according to the present invention have been described above, it should be understood that they have been presented by way of illustration and example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. All patents and publications discussed herein are incorporated by reference herein in their entirety.
This application claims the benefit under 35 U.S.C. §119(e) of U.S. Appl. No. 60/910,768 filed Apr. 9, 2007, which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60910768 | Apr 2007 | US |
