Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2001-04-27
2003-12-30
Layno, Carl (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C600S544000
Reexamination Certificate
active
06671555
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the treatment of neurological disorders, and more particularly techniques for the treatment of epileptic seizures.
BACKGROUND OF THE INVENTION
Epilepsy is a condition characterized by recurrent seizures, which are the outward manifestation of excessive and/or hyper-synchronous abnormal electrical activity of neuronal structures of the brain. A seizure occurs when the electrical activity of brain structures or even the whole brain becomes abnormally “synchronized.” This is the operational definition of an epileptic seizure.
A seizure patient may suffer from any combination of different types of seizures. Grand mal seizures are the most common form of epilepsy and are characterized by convulsions with tonic-clonic contractions of the muscles. Absence seizures (previously referred to as “petit mal”) are characterized by a brief and sudden loss of consciousness. The psychomotor form of seizures is characterized by a clouding of consciousness for one or two minutes. A complex partial seizure is characterized by a complete loss of consciousness. The type of seizure experienced is typically dependent upon the portion of the cerebral cortex where hypersynchronous activity is occurring. Many types of seizures generally involve the entire brain, while certain types, such as partial seizures, begin in one part of the brain and may remain local.
Regardless of the type of epilepsy, seizures significantly limit the autonomy of the patient. When hit with a seizure, the patient typically loses some level of control of his/her body. In most cases, seizures occur without prior warning to the patient. As a result, epileptic seizures pose a serious safety hazard to the patient and others surrounding the patient. For example, a patient hit with a sudden seizure while driving a car may endanger the patient's own safety as well as the safety of others. Seizure patients are also exposed to a risk of bodily harm when operating machinery and even in daily activities such as crossing a street or going down stairs. In addition to this safety hazard, each seizure will further damage brain structures often resulting in progressive loss of brain function over time.
Researchers have developed a number of techniques for treating seizure disorders and its symptoms. For example, research has shown that inhibiting (namely, reducing the excitation of neurons) the substantia nigra in the brain increases the threshold for seizure occurrence. Researchers have also found that increasing the activity of neurons in the external Globus Pallidum (GPe) increases inhibition of neurons in the subthalamic nucleus, which in turn inhibits neural activity in the substantia nigra.
Neurosurgeons have also been able to diminish the symptoms of many neural disorders by lesioning certain brain areas. Examples include lesioning the ventral lateral portion of the internal Globus Pallidus and the Vim Thalamus for treating movement disorders. Electrical stimulation of the nervous system has also been used to suppress seizures. Finally, infusion of certain drugs into a region of the brain can affect the excitability of the neurons at the site of infusion as disclosed in U.S. Pat. No. 5,713,923 (Ward et al.) assigned to Medtronic, Inc.
Others have studied the effects of electrically stimulating the vagus nerve as a means of suppressing epileptic activity. It has been observed that stimulation of the vagus nerve with certain parameters caused de-synchronization of the brain's electrical activity in animal models. These concepts were disclosed by Zabara in U.S. Pat. Nos. 4,867,164 and 5,025,807.
Under another approach, researchers have devised algorithms to detect the onset of a seizure. Qu and Gotman reported a system that recognizes patterns of electrical activity similar to a template developed from recording an actual seizure. See H. Qu and J. Gotman, “A Seizure Warning System for Long-term Epilepsy Monitoring”, Neurology, 1995;45:2250-2254. Also, see I. Osario, M. Frei, D. Lerner, S. Wilkinson, “A Method for Accurate Automated Real-time Seizure Detection”, Epilepsia, Vol. 36, Suppl. 4, 1995. In each of these techniques for recognizing the onset of a seizure, the developers employ two processes. The first process is to extract certain features from the signals representing the electrical activity of the brain. Examples of the signal features include the signal power or the frequency spectrum of the signals. The second process is to recognize a pattern or set of values for those features that characterize a brain state that will reliably lead to a seizure.
Using pattern recognition techniques, closed-looped protocols for responding to the onset of an epileptic seizure have also been suggested. For example, U.S. Pat. Nos. 6,128,538 and 6,134,474 report closed-loop systems for identifying and responding to a neurological disease, such as epilepsy. These systems, however, identify and respond to neurological events that have already begun. Once started, these events may be difficult to correct. Therefore, a need for more efficient and effective treatments of neurological events continues to exist. Table 1 lists documents that disclose systems and methods that provide for seizure detection.
TABLE 1
U.S.
Pat. No.
Inventors
Title
4,867,164
Zabara
Neurocybernetic prosthesis
5,025,807
Zabara
Neurocybernetic prosthesis
5,713,923
Ward
Techniques for treating epilepsy by brain
et al.
stimulation and drug infusion
6,128,538
Fischell
Means and method for the treatment of
et al.
neurological disorders
6,134,474
Fischell
Responsive implantable system for the
et al.
treatment of neurological disorders
H. Qu and J. Gotman, “A Seizure Warning
System for Long-term Epilepsy Monitoring”,
Neurology, 1995;45:2250-2254
I. Osario, M. Frei, D. Lerner, S. Wilkinson,
“A Method for Accurate Automated Real-time
Seizure Detection”, Epilepsia, Vol. 36,
Suppl. 4, 1995.
All documents listed in Table 1 above are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and claims set forth below, many of the devices and methods disclosed in the patents of Table 1 may be modified advantageously by using the techniques of the present invention.
SUMMARY OF THE INVENTION
The present invention has certain objects. That is, various embodiments of the present invention provide solutions to one or more problems existing in the prior art with respect to the treatment of neurological disorders, and with respect to the treatment of epileptic seizures in particular. Such problems include, for example, treating neurological events only after they have started and, in particular, treating epileptic seizures only after they have started, the present inability to predict the likelihood of the occurrence of an impending neurological event, the present inability to predict the likelihood of the occurrence of an impending epileptic seizure, the present inability to provide therapy to a patient in order to avert the onset of an impending, but not yet started, neurological event, and the present inability to provide therapy to a patient in order to avert the onset of an imminent, but not yet started, epileptic seizure. Various embodiments of the present invention have the object of solving at least one of the foregoing problems.
It is an object of the present invention to overcome at least some of the disadvantages of the foregoing systems by providing a system and method that probe the excitable state of the brain or a specific sub region of the brain and relate a measurement acquired via the probe to the likelihood of the occurrence of an impending neurological event.
It is a further object of the invention to provide a method of signal analysis to predict the likelihood of the occurrence of a neurological disorder or event prior to the start of the event and to provide therapy to the brain when a neurological disorder and/or event is predicted.
In addition, it is a
Gielen Frans L. H.
Wadman Wytse J.
Albrecht John W.
Layno Carl
Medtronic Inc.
Waldkoetter Eric R.
Woods Thomas F.
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