Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2001-06-15
2004-08-24
Jastrzab, Jeffrey R. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
Reexamination Certificate
active
06782292
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to implantable drug delivery and electrical stimulation systems and methods, and more particularly relates to utilizing one or more implantable devices to deliver electrical stimulation and/or one or more stimulating drugs as a treatment for mood and/or anxiety disorders.
BACKGROUND OF THE INVENTION
Recent estimates indicate that more than 19 million Americans over the age of 18 years experience a depressive illness each year. The American Psychiatric Association recognizes several types of clinical depression, including Mild Depression (Dysthymia), Major Depression, and Bipolar Disorder (Manic-Depression). Major Depression is defined by a constellation of chronic symptoms that include sleep problems, appetite problems, anhedonia or lack of energy, feelings of worthlessness or hopelessness, difficulty concentrating, and suicidal thoughts. Approximately 9.2 million Americans suffer from Major Depression, and approximately 15 percent of all people who suffer from Major Depression take their own lives. Bipolar Disorder involves major depressive episodes alternating with high-energy periods of rash behavior, poor judgment, and grand delusions. An estimated one percent of the American population experiences Bipolar Disorder annually.
Significant advances in the treatment of depression have been made in the past decade. Since the introduction of Selective Serotonin Reuptake Inhibitors (SSRIs), e.g., Prozac® antidepressant, many patients have been effectively treated with anti-depressant medication. New medications to treat depression are introduced almost every year, and research in this area is ongoing. However, an estimated 10 to 30 percent of depressed patients taking an antidepressant are partially or totally resistant to the treatment. Those who suffer from treatment-resistant depression have almost no alternatives.
Electroconvulsive Therapy (ECT) is an extreme measure that is used today to treat such patients. In ECT, a low-frequency electrical signal is sent through the brain to induce a 30- to 60-second general seizure. The side effects include memory loss and other types of cognitive dysfunction.
Repetitive Transcranial Magnetic Stimulation (rTMS) is currently being explored as another therapy for depression. Kirkcaldie et al. (1997) reported a greater than 50 percent response rate when applying rTMS to the left dorsolateral prefrontal cortex of 17 depressed patients. In addition, a company headquartered in Houston, Tex. is currently exploring the application of vagus nerve stimulation to treatment-resistant depression; Rush, et al. (1999) report a success rate of 40-50 percent in a recent study of 30 patients.
Deep Brain Stimulation (DBS) has been applied to the treatment of central pain syndromes and movement disorders, and it is currently being explored as a therapy for epilepsy. For instance, U.S. Pat. No. 6,016,449 to Fischell, et al. discloses a system for the electrical stimulation of areas in the brain for the treatment of certain neurological diseases such as epilepsy, migraine headaches and Parkinson's disease. However, Fischell et al. do not teach or suggest the use of such a system for the treatment of mood disorders, such as depression.
As was recently reported by Bejjani, et al. (1999), a patient responded to DBS of an area near the thalamus during the therapeutic placement of a stimulator for tremor, by lapsing into a sudden and marked depressive episode. The depression ceased within a couple of minutes after stimulation was halted, and the patient demonstrated a rebound ebullience. This phenomenon was repeated in the same patient several weeks later for purposes of verification.
New functional imaging techniques have led to the identification of several sites in the brain that demonstrate abnormal characteristics (e.g., hypoperfusion) in depression. Several regions of the brain have been identified as having decreased blood flow or metabolism in depressed patients compared to controls. In an important 1997 study, Drevets et al. reported that the subgenual prefrontal cortex (i.e., the anterior cingulate gyrus ventral to the corpus callosum) demonstrated decreased blood flow or metabolism in patients with Major Depression and with Bipolar Disorder compared with psychiatrically normal controls.
Similarly, Ebmeier et al. (1997), in a review of several studies, reported that the anterior cingulate gyrus demonstrates decreased blood flow or metabolic activity in depressed patients. In a 1999 review, Davidson et al. cite several reports that indicate that the left anterior cingulate gyrus demonstrates decreased activity in depression and furthermore demonstrates increased activity in depressed patients who respond to antidepressant medication.
Galynker et al. (1998) reported that decreased blood flow in the left dorsolateral prefrontal cortex correlated with severity of negative symptoms in depressed patients. (The left dorsolateral prefrontal cortex is the primary target of rTMS in the treatment of depression.) Drevets, in an extensive 1998 review, generalizes these results to suggest that the dorsal prefrontal cortex demonstrates decreased activity in depression while the ventral prefrontal cortex demonstrates increased activity.
Bench et al. (1992) reported decreased blood flow in the left anterior cingulate gyrus and the left dorsolateral prefrontal cortex in depressed patients as compared with controls, and further reported increased blood flow in the cerebellar vermis in depressed patients with depression-related cognitive impairment.
As stated above, Drevets reported that the ventral prefrontal cortex demonstrates increased activity in depressed patients, and further reported evidence that blood flow and metabolism are abnormally increased in the medial thalamus in patients with Major Depression and Bipolar Disorder as compared with controls. As also stated above, Bench reported abnormally increased blood flow in the cerebellar vermis in depressed patients with depression-related cognitive impairment. Abercrombie et al. (1998) reported that the metabolic rate in the right amygdala predicts negative affect in depressed patients (although no absolute difference was found between depressed and control subjects).
Recent studies of neurotransmitter receptors in the brains of patients with depression also suggest possible sites of the brain that are abnormal in depression. Stockmeier et al. (1997) reported an increased number of serotonin receptors in the dorsal raphe nucleus of suicide victims with major depression as compared with psychiatrically normal controls. Similarly, Yavari et al. (1993) reported decreased activity in the dorsal raphe nucleus in a rat model of endogenous depression. Klimek et al. (1997) reported reduced levels of norepinephrine transporters in the locus coeruleus in major depression. These findings corroborate existing anatomical evidence regarding the functions of these areas.
In 1998, Saxena et al. performed a study of the pathophysiology of obsessive-compulsive disorder. They found that at least a subgroup of patients with obsessive-compulsive disorder may have abnormal basal ganglia development. They observed that obsessive-compulsive disorder symptoms are associated with increased activity in the orbitofrontal cortex, caudate nucleus, thalamus, and anterior cingulate gyrus.
The dorsal and median raphe nuclei, which course within the medial forebrain bundle, the dorsal longitudinal fasciculus, and the medial longitudinal fasciculus, have long been known to have major serotonergic projections to the limbic system. Medications that block serotonin reuptake (thus increasing its level) are effective therapy for depression, panic disorder, obsessive-compulsive disorder, and other mood and anxiety disorders.
The locus coeruleus, which lies near the floor of the fourth ventricle, has major noradrenergic projections to virtually the entire central nervous system, including the cerebral cortex, the limbic system, and the hypothalamus. Medications that dually block serotonin a
Advanced Bionics Corporation
Bishop Laura Haburay
Gold Bryant R.
Jastrzab Jeffrey R.
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