Surgery – Diagnostic testing – Structure of body-contacting electrode or electrode inserted...
Reexamination Certificate
1999-02-23
2001-12-11
Cohen, Lee S (Department: 3739)
Surgery
Diagnostic testing
Structure of body-contacting electrode or electrode inserted...
C600S544000, C607S116000
Reexamination Certificate
active
06330466
ABSTRACT:
TECHNOLOGICAL FIELD
This application relates to the use of electrode probes in stereotactic neurosurgery.
BACKGROUND
Certain neurosurgical procedures require the determination of the precise location of target tissue, and fine discrimination of the target from adjacent non-target tissue. For example, during a “pallidotomy,” a procedure often performed on patients with Parkinson's disease, the neurosurgeon must carefully introduce a lesioning device into a small area deep in the brain called the Globus pallidus internus (Gpi), while avoiding the adjacent Globus pallidus externus (Gpe). Computed tomography (CT) and magnetic resonance imaging (MRI) are typically used to guide the surgeon to the Gpi/Gpe region. More precise, localized targeting is often achieved by means of electrophysiological localization techniques.
Conventional electrophysiological localization techniques typically involve the insertion of a tungsten electrode into the brain to detect neural activity. Because different brain areas produce characteristic patterns of neural activity, the signals picked up by the electrode at different locations are used to finely distinguish between the different brain areas. The Gpe and Gpi, for example, produce different characteristic patterns of activity, as monitored on the tungsten electrode. This knowledge is used during a pallidotomy to determine the boundary between the two structures, which allows the subsequent introduction of a lesion into the Gpi while avoiding lesioning the Gpe.
Because the tungsten electrode detects activity at only one site in the brain at any given time, the surgeon moves the electrode sequentially to multiple sites, stopping at each site for some time to monitor the local neuronal activity. Typically the electrode is inserted into the brain at a few different surface locations, and several depth locations are monitored along each electrode insertion track. Characteristic patterns of neural activity are noted at several of these electrode locations. As this information builds up over the course of the surgery, the surgeon derives an anatomical and/or functional map of that part of the brain.
The success of electrophysiological localization depends largely on the skill of the surgeon, who must accurately position the electrode at several sites in the brain and then accurately interpret the measurements taken by the electrode. Even the slightest misguidance of the electrode or misinterpretation of the measurements can lead to brain damage. As the number of monitored sites increases, so does the time required, and therefore the risk of brain damage, the cost of surgery, and the risk to the patient's health.
SUMMARY
The inventors have developed a technique for using a multi-electrode probe to rapidly create an electrophysiological depth profile during stereotactic neurosurgery. The depth profile provides information about concurrent neuronal activity at a set of positions, or depths, along the probe insertion track. This information supplants the limited information that neurosurgeons currently receive by taking a set of individual measurements at multiple depth positions with a single-electrode probe, and then manually assembling the sequentially-obtained information into a composite depth profile. One measurement with the multi-electrode probe allows the derivation of a depth map that normally is possible only with many measurements using a single-electrode probe, thus saving surgical time and reducing the associated costs and risks. Simultaneous measurement at multiple locations, which is impossible with single-electrode probes, also provides information about correlations between different neural groups. This information is useful in improving the quality of data interpretation and surgical targeting.
In one aspect, the invention features a technique for using a multi-electrode probe to locate a target site in a brain during stereotactic neurosurgery. The surgeon first identifies an area of a brain that includes a target site to be treated. The surgeon then inserts a multi-electrode probe into this area of the brain. The probe includes multiple electrodes that concurrently produce output signals indicative of concurrent neuronal activity at multiple sites in the brain. The output signals are used to generate a user interface that provides an indication of the level of concurrent neuronal activity at each of the multiple sites.
In another aspect, the invention features a multi-electrode probe system for use in locating a target site in a brain during stereotactic neurosurgery. The system includes a multi-electrode probe inserted into an area of a brain that includes a target site to be treated. The probe includes multiple electrodes that produce output signals indicative of concurrent neuronal activity at multiple sites in the brain. The system also includes a processor that receives the output signals from the electrodes and derives the level of concurrent neuronal activity that occurs at each of the multiple sites. A user interface displays an indication of the level of concurrent neuronal activity at each of the multiple sites.
In some embodiments, the user interface provides a depth profile indicating the level of concurrent neuronal activity at various depths in the brain. Some versions of the user interface provide an indication of spike rate for individual neurons at the multiple sites. The user interface often includes a graphical display or a sound signal that provides a visual or audible indication, respectively, of the level of neuronal activity at each of the multiple sites. Other embodiments require the surgeon to provide a stimulus directed to neurons at the target site to increase the level of neuronal activity at the target site.
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Hofmann Ulrich G.
Kewley David T.
Thompson John H.
California Institute of Technology
Cohen Lee S
Fish & Richardson P.C.
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