Patent Application
20250205461
Embodiments of the present invention generally relate to cerebrospinal fluid shunts and, in particular, to an improved apparatus for shunting cerebrospinal fluid that may be used to treat hydrocephalus.
In a normal mammal, cerebrospinal fluid (CSF) is created within ventricles of the brain and flows into and out from the spinal column. CSF flow is affected by a combination of forces acting upon fluids within the body including arterial pulsations, body movement, body orientation (i.e., standing, sitting, or prone), atmospheric pressure, respiration, diaphragmatic movement, abdominal motion, and the like. When the flow of CSF is constrained, a condition known as hydrocephalus occurs which results in CSF pressure increasing in the head. Untreated hydrocephalus may lead to brain damage and/or death.
Currently, hydrocephalus is treated with a CSF shunt that facilitates channeling CSF from the head or spine into another portion of the body (e.g., vein or peritoneal cavity) where the CSF is absorbed. A typical shunt comprises a ventricular catheter, a subgaleal catheter, a one-way pressure activated valve, and a distal subcutaneous peritoneal catheter. Some shunts also include a reservoir preceding the valve and an anti-siphon regulatory device after the valve. The ventricular catheter has its proximal end placed in a ventricle in the brain and a distal end that is connected to the reservoir or valve. The reservoir, valve and anti-siphon device may be connected in series and placed under the skin, typically, on the back or side of the skull. The peritoneal catheter has a proximal end that is connected to the anti-siphon device and a distal end extending to the site of CSF absorption (into a vein, the peritoneal cavity, or pleural cavity).
In operation, as CSF is produced in the ventricles and increases the pressure in the ventricles, the valve opens when the pressure exceeds the pressure threshold of the valve, the catheter resistance, the intraperitoneal pressure, plus the hydrostatic pressure difference. When the valve opens, CSF flows through the shunt to the peritoneal cavity or vein where the CSF is absorbed by the body. The reservoir is provided as a CSF access device and the anti-siphon device ensure that a siphon effect does not maintain the valve in on open position and drain all the CSF from the brain and spine (the reservoirs are in general only deformable by significant external pressure, they are otherwise non-compliant to physiological pressures).
A major problem with a shunt is that it is purely a pressure-based device that forms an alternate CSF path. Consequently, the typical shunt attenuates the other forces that effect CSF flow. Thus, the complex flow path for CSF is bypassed by the shunt and results in a variety of medical conditions such as intracranial hypotension and slit ventricles.
In addition, shunts routinely become obstructed and cease shunting CSF. One specific obstruction that routinely occurs is caused by the choroid plexus in the ventricle entering the open end of the ventricular catheter. Once clogged, brain surgery is required to replace the ventricular catheter.
Therefore, there is a need for apparatus for shunting CSF that more closely mimics the complex movement of CSF within the body and mitigates ventricular catheter obstruction.
Apparatus for shunting cerebrospinal fluid is provided substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.
Various features and advantages of the present disclosure may be appreciated from a review of the following detailed description of the present disclosure, along with the accompanying figures in which like reference numerals refer to like parts throughout.
So that the manner in which the various features of the present invention can be understood in detail, a particular description of the invention, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
Embodiments of the present invention comprise a cerebrospinal fluid (CSF) shunt having an improved ventricular catheter and/or an artificial dural sac. Such a shunt is improved over currently available shunts by including a sleeved ventricular catheter, an artificial dural sac or both. The sleeved ventricular catheter comprises an inner catheter having a plurality of holes in the sides of the catheter and a sleeve having a larger diameter than the inner catheter which circumscribes the inner catheter. The sleeve is coupled (for example, via ligature) to the inner catheter at a distance away from the inner catheter tip. The inner catheter comprises a plurality of holes near the distal end of the inner catheter. The sleeve defines a gap surrounding the inner catheter to allow CSF to flow in the gap to the holes in the inner catheter. As such, the sleeve protects the holes from becoming obstructed with brain matter, e.g., choroid plexus. The sleeved ventricular catheter may be used in a conventional shunt, e.g., connected to a reservoir (optional), one-way valve, anti-siphon device (optional) and a peritoneal catheter.
The shunt may further include, or alternatively include, an artificial dural sac (ADS). The ventricular catheter, whether standard or sleeved, is coupled to a 3-port connector reservoir where a first port is coupled to the coupling catheter (or subgaleal catheter), a second port is coupled to a one-way pressure valve (with siphon regulatory device (such as an anti-syphon device or Starling resistor) and a third port is coupled to a subcutaneous catheter that leads to the ADS located in the abdomen. When the ADS is used, the syphon regulatory device is necessary (not optional as in the embodiment without an ADS) to avoid having the ADS empty into the peritoneal cavity when the head is elevated. The ADS is located caudal to the level of the siphon regulatory device. In operation, the ADS and its catheter fill with a volume of CSF. The ADS is a flexible pressure responsive reservoir. When compressed, the ADS supplies CSF back to the ventricles in a more natural flow pattern, e.g., the ADS is compressed in response to increased intra-abdominal pressure, increase in hydrostatic pressure (a head down position), a decreasing intracranial pressure (as during inspiration) and the like.
The ventricular catheter 112 has a proximal end 132 that is positioned in one of the ventricles 110A or 110B. The ventricular catheter 112 extends outside the skull though a burr hole and and is coupled to a coupling or subgaleal catheter 134. The coupling catheter 134 is routed subcutaneously to the connector reservoir 114. The ventricular catheter 112 is described in detail with respect to
Once placed in a ventricle, the sleeved catheter 202 facilitates CSF flow into and/or out of a distal end opening 418 and into a circumferential gap 420 between the inner catheter 206 and the outer catheter 204. In one embodiment, the outer catheter 204 is sealed to the inner catheter 206 at a junction with the elbow 208. The elbow 208 is manufactured of hard plastic such that a ligature 210 may be formed by tying a suture around the inner and outer catheters 206 and 204. The outer sleeve catheter 204 protects the apertures 406 in the inner cathode from being clogged with brain matter such as the choroid plexus.
In one embodiment, the inner surface of the outer catheter 204 and the outer surface of the inner catheter 206 may be smooth (not shown). In other embodiments, the inner surface of the outer catheter 204 and the outer surface of the inner catheter 206 may have a plurality of longitudinal ribs 500/502 running the length of the catheters 204 and 206. In one embodiment there may be 3 ribs 500/502 on each surface. The ribs 500/502 may be positioned at offset 60 degree intervals and are intended to maintain the gap 420 between the catheters 204 and 206 to promote ingress and egress of CSF. In an exemplary embodiment, the outer catheter 204 has an inner diameter of about 3.2 mm, and an outer diameter of about 3.6 mm and an inner diameter of the rib 500 of about 2.7 mm, while the inner catheter 206 has an outer diameter of about 2.2 mm, an inner diameter of 1.8 mm, and an outer diameter of the rib 502 of about 2.7 mm.
Although the sleeved ventricular catheter 202 is shown as functioning with a shunt 50 having an ADS, it should be understood that the sleeved ventricular catheter 202 may be used in a conventional shunt assembly, e.g., the sleeved ventricular catheter 202 is coupled to the one way valve without the use of a Y-junction reservoir. In such an embodiment, the sleeved ventricular catheter 202 provides the benefit to the conventional shunt of having a reduced chance of becoming obstructed due to the protective nature of the sleeve and, if a ventricular revision is needed because both gap 420 and opening 418 become occluded, the catheter 202 will not be tethered inside the ventricle. An untethered catheter lessens the risk of bleeding with the removal of the catheter protected by the sleeve.
To allow the ADS 130 to continue functioning as a child grows, additional catheter 122 is placed in the pre-peritoneal space such that the extra catheter extends as the child grows. Additionally, during initial shunt placement surgery, the ADS may be used as a reservoir for one or more antibiotics (such as gentamicin) using a prophylactic dose.
Here multiple examples have been given to illustrate various features and are not intended to be so limiting. Any one or more of the features may not be limited to the particular examples presented herein, regardless of any order, combination, or connections described. In fact, it should be understood that any combination of the features and/or elements described by way of example above are contemplated, including any variation or modification which is not enumerated, but capable of achieving the same. Unless otherwise stated, any one or more of the features may be combined in any order.
As above, figures are presented herein for illustrative purposes and are not meant to impose any structural limitations, unless otherwise specified. Various modifications to any of the structures shown in the figures are contemplated to be within the scope of the invention presented herein. The invention is not intended to be limited to any scope of claim language.
Where “coupling” or “connection” is used, unless otherwise specified, no limitation is implied that the coupling or connection be restricted to a direct physical coupling or connection.
Where conditional language is used, including, but not limited to, “can,” “could,” “may” or “might,” it should be understood that the associated features or elements are not required. As such, where conditional language is used, the elements and/or features should be understood as being optionally present in at least some examples, and not necessarily conditioned upon anything, unless otherwise specified.
Where lists are enumerated in the alternative or conjunctive (e.g., one or more of A, B, and/or C), unless stated otherwise, it is understood to include one or more of each element, including any one or more combinations of any number of the enumerated elements (e.g. A, AB, AC, ABC, ABB, etc.). When “and/or” is used, it should be understood that the elements may be joined in the alternative or conjunctive.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
