Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1998-07-13
2001-04-10
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C606S130000, C604S891100, C600S434000
Reexamination Certificate
active
06216030
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for delivering treatment to a specific location in a portion of the body and the method of using this apparatus to achieve this treatment delivery. More specifically, this invention relates to the use of a magnetic object to achieve this treatment delivery to the specific location in the body part.
2. Prior Art
Current treatment delivery techniques used for the treatment of many illnesses, especially neurological disorders, are suboptimal. The major limitations to existing methods result from lack of regional specificity within the body portion being treated. This lack of regional specificity refers to the inability to cause drugs, etc. to localize to specific regions most affected by the disease being treated.
This is especially true of the brain. As an example, in Parkinson's disease dopaminergic innervation of a specific subcortical structure called the striatum is lost. Pharmacologic therapy is intended to restore dopamine function in the striatum, but in practice pharmacologic agents are given systemically, resulting in the entire brain being bathed in these chemicals. It is thought that many of the serious side effects observed with conventional therapy result from unnecessary pharmacologic stimulation of normal brain outside the targeted region (striatum). Another example is temporal lobe epilepsy. In this disorder only one portion of the brain displays abnormal electrical activity, but current treatments involve exposing the entire brain to potentially toxic drugs.
The brain presents an additional major limitation to existing methods due to the inability of the drugs to pass through the blood brain barrier. The blood brain barrier (BBB) refers to the unique permeability properties of the cerebral vasculature. Unlike systemic blood vessels, cerebral vessels are generally quite impermeable, thus the term BBB. Many drugs that pass easily through systemic blood vessels cannot pass through the BBB and enter the brain. This dramatically reduces the ability to deliver the desired drugs to the brain. An example of this is Parkinson's disease. The molecule that is lost in this disorder is dopamine. Ideally the disorder would be treated by delivering dopamine to the brain. However, the BBB is impermeable to dopamine and this agent cannot be used systemically, that is orally or intravenously. Instead, a less optimal strategy has been adopted of providing a BBB permeable precursor to dopamine synthesis, L-DOPA.
The invention described below has been designed to circumvent the shortcomings of conventional therapy and to provide an ideal treatment delivery system for the treatment of diseases, especially focal neurological disorders.
SUMMARY OF THE INVENTION
With this invention, treatment such as with drugs will be chronologically and directly delivered to specific locations in a particular body part by way of a magnetically guided, treatment carrier means.
In one embodiment of the invention, the treatment carrier means is a polymeric implant with a linear, string-like configuration that presents a very small cross-sectional area as it is led through the body by a thin leading magnet. The polymer string is also very flexible so that the trailing string follows precisely the leading magnet as it is directed along the body. This flexibility results in the polymer string sliding along the tunnel created by the leading magnet.
In another embodiment, this treatment carrier means is a flexible gelatin structure or a flexible hollow biodegradable tube which encases the drug or a slurry of cells.
In another embodiment, the treatment carrier means is an implant sheath device with a permeable region which is placed within the specific body location and a nonpermeable region. The distal end of the nonpermeable region remains at the surface of the body. A pump may be attached to the distal end and treatment infused to determine an appropriate dose-response calculation. This treatment may be chronologically pumped, infused or, preferably, a semi-permeable membrane catheter filled with the treatment is magnetically placed inside the implant sheath device.
In the preferred embodiment, the magnetic means has an approximately 2 mm cross-sectional diameter and has a torpedo-like shape.
The treatment carrier means is attached to the magnetic object by a connection means so that, when the treatment carrier means is located in the specific location, the magnetic object and treatment carrier means may be separated. This connection means could consist of a heat-soluble biodegradable connector link so that the magnetic object could be inductively heated and cause the melting of this heat-soluble biodegradable connector link. This connection means could also be a spring-mechanical mechanism so that the magnetic object is disconnected from the treatment carrier means by a simple magnetic pulse sequence. Other types of connection means are also envisioned for connecting and later separating the magnetic object from the treatment carrier means.
This apparatus and method are especially useful to chronically and directly deliver drugs or a slurry of cells to precise regions of the brain. The flexibility of the treatment carrier means allows it to follow precisely the leading magnet as it is directed along the uneven contours of the brain target region. This flexibility results in the treatment carrier means sliding along the tunnel created by the magnetic object and assuming a final position and a shape that precisely follows the convoluted volume of the brain target.
The preferred magnetic guidance system is found in U.S. application Ser. No. 167,217 entitled “HGR Video Tumor Fighter”, and this apparatus and method are incorporated herein. The ability to precisely manipulate a small intracranial magnetic object has already been demonstrated using the HGR Video Tumor Fighter system. Basically, an electromagnet is positioned outside of the body part for producing a magnetic field which captures the magnetic object. This electromagnet may be either a simple coil system attached to a robotic arm which moves the electromagnet adjacent the body part, or a multicoil, superconducting electromagnet system surrounding the body part. In either case, the robotically moved electromagnet or multicoil electromagnet system moves the magnetic object within the body part to a desired location. A computer controls either the robotic arm or the multicoil current magnitudes and directions. The computer also provides visualization for observing the location and movement of the magnetic object and treatment carrier means.
The advantages of this invention with treatment delivery to precise regions of the brain are as follows:
1. The BBB is bypassed. By delivering drugs or cells directly into brain tissue, access is gained to the targeted tissue without having to pass through a blood vessel and across the BBB.
2. Drugs or cells are delivered to the specific targeted subregion of the brain. As the drugs are released from the polymer, they diffuse to immediately adjacent brain regions but do not unnecessarily expose the remainder of the brain.
3. Drugs are released chronically in a controlled release fashion. Polymeric compounds can be designed to release the drug over a period of many months or several years.
4. Optimal dispersion of polymer is achieved by remote, non-linear magnetic manipulation. Most brain structures that will be desired treatment delivery targets have non-linear contours. As an example, one element of the striatum is arranged in the shape of a “C”. Given a fixed volume of polymer, the ideal dispersion configuration would maximize the ratio of: target volume within diffusion distance of polymer)/(degree of mechanical displacement of target volume by polymer implant).
5. A thin string of polymer contoured exactly to the non-linear configuration of the subcortical target structure maximizes this ratio. Remote manipulation is the only means by which to safely achieve this final configuration.
6. The procedure will be s
Gillies George T.
Grady M. Sean
Howard Matthew A.
Mayburg Mar
Ritter Rogers C.
Lateef Marvin M.
Mantis Mercader Eleni
The University of Virginia Alumni Patents Foundation
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