Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2000-02-24
2003-08-19
Layno, Carl (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C600S033000, C600S508000
Reexamination Certificate
active
06609030
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the treatment of psychiatric disorders by stimulating appropriate regions of the thalamus, and more particularly to a method of modulating pathological electrical and/or chemical activity of the brain by electrical and/or chemical stimulation of the corresponding nucleus or nuclei of the thalamus, and most specifically to the stimulation of the dorsomedial nucleus of the thalamus.
2. Description of the Prior Art
The treatment of psychiatric disorders by neurosurgical techniques has an extensive history. In the early 1930's Fulton and Jacobsen first recognized that an experimentally induced neurotic behavior in chimpanzees could be abolished by frontal lobectomy. Within a few years, Freeman and Watts developed the first psychosurgical procedure for humans known as the frontal lobotomy. As the inherent physiology of the frontal lobe became more evident, the original freehand procedure of Freeman and Watts became less and less extensive. By the late 1940's, the method of stereotaxis, in which the patient's brain is modeled in 3-dimensional space for exquisite targeting accuracy, merged with lesioning techniques resulting in an even more efficacious and safe psychosurgical procedure. Further developments of stereotactic equipment have combined with novel advancements in functional and anatomic imaging to encompass the state of the art in the neurosurgical treatment of psychiatric disorders today. However, the fundamental limitation of these lesioning techniques is that they are inherently irreversible and static in nature. There is no proverbial “off” switch to alleviate side effects and no way to adjust the desirable effects in response to a patient's changing symptom profile.
Within the field of neurosurgery, the use of electrical stimulation for treating pathologies, including such disorders as compulsive eating, chronic pain, and movement disorders, such as Parkinson's disease essential tremor, has been widely discussed in the literature. It has been recognized that electrical stimulation holds significant advantages over alternative methods of treatment, for example lesioning, inasmuch as lesioning can only destroy nerve activity. In many instances, the preferred effect is to stimulate or reversibly block nervous tissue. Electrical stimulation permits such stimulation of the target neural structures, and equally importantly, it does not require the destruction of the nervous tissue (it is a reversible process, which can literally be shut off or removed at will).
Another technique which offers the ability to affect neuronal function in a reversible and dynamic fashion is the delivery of drugs directly to target tissues via a subcutaneously implanted pump. Such drugs, either traditional psychiatric agents or chemicals mimicking neurotransmitters, could be instilled at such low doses as to completely avoid the side effects so common to moden pharmacotherapy. Such doses could also be tailored in magnitutde with regard to a particular patient's varying symptomatology. A chemical neuromodulating system could be implanted as a primary treatment strategy or in combination with an electrically based one. A combination therapeutic approach, one combining electrical and chemical means, would be penultimate to regenerating healthy neuronal tissue.
Within this field, however, disorders manifesting gross physical dysfunction, not otherwise determinable as having emotional or psychiatric origins, comprise the vast majority of those pathologies treated by deep brain stimulation. A noteworthy example of treatment of a gross physical disorder by electrical stimulation is included in the work of Alim Benabid, and his research team, who have proposed a method of reducing, and in some cases eliminating, the temor associated with Parkinson's disease by the application of a high frequency electrical pulse directly to the subthalamic nucleus (see Neurosurgical Operative Atlas, Vol. 8, March 1999, pp. 195-207, Chronic Subthalamic Nucleus Stimulation For Parkinson's Disease; and New England Journal of Medicine, Vol. 339, October 1998, pp. 105-1111, Electrical Stimulation of the Subthalamic Nucleus in Advanced Parkinson's Disease).
Conversely, direct neuroaugmentation treatments for disorders which have traditionally been treated by behavioral therapy or psychiatric drugs, has been largely limited to the stereotactic lesioning procedures mentioned above. The are four lesioning techniques mostly in use today: cingulotomy, capsulotomy, subcaudate tractotomy, and limbic leucotomy. Such procedures have been applied to date in the treatment of Affective disorders and Anxiety disorders. If one critically examines the results of these procedures in the literature, it would be apparent, when applied to a carefully selected patient population in conjuction with modern equipment and imaging techniques, these procedures are both efficacious and safe. In fact, in a certain subset of patients who have failed all conventional (pharmacotherapy and psychotherapy) treatments, these neurosurgical procedures are the only efficacious options available. If would follow that electrical and/or chemical neuromodulating techniques with their inherent reversibility and adjustability would an even better solution than the traditional lesioning techniques. To date, however, intracranial neuromodulation techniques have been largely unexplored. Only recently, in the Oct. 30, 1999 issue of Lancet, have Meyerson et al. described a technique for deep brain electrical stimulation of the anterior internal capsule for OCD patients. While the results are preliminary, they are also quite promising as three of the four patients had good results.
Another effort has been made to treat psychiatric disorders via peripheral nerve stimulation. A noteworthy example is the effort to control compulsive eating disorders by stimulation of the vagus nerve which has been described by Wernicke, et al. in U.S. Pat. No. 5,263,480. This treatment seeks to induce a satiety effect by stimulating the afferent vagal fibers of the stomach. For patients having weak emotional and/or psychological components to their eating disorders, this treament can be effective insofar as it eliminates the additional (quasi-normal) physio-chemical stimulus to continue eating. This is especially true for patients who exhibit subnormal independent functioning of these fibers of the vagus nerve. For compulsive eating patients who are not suffering from an insufficient level of afferent vagal nerve activity resulting from sufficient food intake, however, the over stimulation of the vagus nerve and potential resultant over abundance of satiety mediating chemicals (cholecystokinin and pancreatic glucagon) may have little effect It has even been suggested that continued compulsive eating, despite overstimulation of the vagus nerve, may exacerbate the emotional component of the patient's disorder. This, therefore, begs the question, is vagus nerve stimulation useful in treating the psychological component of the disorder of compulsive eating, or is it simply a method of minimizing the additional, but natural, pressures to eat because of normal physical hunger. More generally, the question may be asked, is peripheral nerve stimulation of any kind the most appropriate method of treatment for disorders which are, at the core, the result of a pathology exhibited in the brain.
If the answer to this question is that the stimulation of a peripheral nerve can result in the release of a chemical which specifically counteracts the psychological pathology, for example if the release of greater amounts of cholecystokinin and pancreatic glucagon had a direct effect on the pathology exhibited in the brain, then, for that patient, the treatment will have a greater probability of success. If, however, as is most probably the case, the increase in the level of activity of the peripheral nerve does not result in the release of such a chemical, and therefore, has no
Kopell Brian H.
Rezai Ali R.
Bortree, Esq. Timothy J.
ElectroCore Techniques, LLC
Errico, Esq. Joseph P.
Layno Carl
LandOfFree
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