Posted by Nickengland on April 4, 2005, at 8:34:28
In reply to Re: Vagus Nerve Stimulation Anyone?, posted by Lydia on April 2, 2005, at 14:12:22
Thanks Lydia,
I found this one too..
VAGUS NERVE STIMULATION FOR UNIPOLAR AND BIPOLAR DEPRESSION
In July 1998, surgeons implanted a pacemaker-like device into the chest of a bipolar patient with severe depression. The implement sends an electrical pulse up a wire into the vagus nerve in the neck at the base of the brain. The treatment, vagus nerve stimulation or VNS, has been in use for epilepsy patients in Europe since 1994 and the US since 1997. Within eight weeks, the patient moved out of his parents’ house and found a job. He did, however, cycle into an irritable mania. Nevertheless, the results were encouraging enough to proceed with a pilot study.
Cyberonics, the Houston company that developed and manufactures the device, first approached Mark George MD, a psychiatrist and neurologist at the Medical University of South Carolina to see if there might be a wider application for VNS. Because epilepsy meds also work for bipolar patients, Dr George thought there might be a parallel, especially when PET scans of VNS patients revealed activity in the prefrontal cortex, cingulate gyru, and amagdyla, all involved in mood. Dr George recruited three other researchers - Lauren Marangell MD at Baylor College of Medicine, A John Rush MD of the University of Texas Southwestern Medical Center, and Harold Sackeim PhD at Columbia University - and together they enrolled 30 depressed unipolar and bipolar patients for an open trial, and 30 more patients a year later.
The patients had been in major depression for more than six years and had failed 16 treatments - including antidepressants, mood stabilizers, and ECT - with mean Hamilton Depression scores of 36.8. Patients were allowed to stay on their current medications According to Dr George, the 60 patients represented "maybe the most ill cohort ever published."
Thirty percent of the patients responded after 12 weeks. A "response" is measured as at least a 50 percent improvement in symptoms. Patients who had failed on two or three antidepressants fared best. Those who failed on more than seven antidepressants did not respond at all. Twenty-one percent of all the patients remitted - that is, they achieved a symptom-free or near symptom-free state - a finding that took the researchers by surprise: "I’ve been treating these kinds of patients for more than a decade and I’ve never seen anything like it" said Dr George.
The bipolar depressed patients had similar results as the unipolar depressed patients. One bipolar patient and one unipolar patient switched into hypomania, causing one drop-out amongst the entire 60.
By way of comparison, clinical drug trials typically include patients with Hamilton Depression scores as low as 16 or 18. In general, seventy percent of those in drug trials respond, but only 30 percent of the responders actually achieve remission. Drop-out rates can be as high as 40 percent.
After one year, 41 percent of the original 30 patients had responded, and 26 had remitted. At least 90 percent of the responders were still responding after one year. In December 2001, at the annual meeting of the American College of Neuropsychopharmacology, the authors presented their latest findings, reporting that after two years response rates had climbed to 54 percent.. Dr George did not rule out the fact that the improved numbers over the course of time could have been due to the patients’ depressions independently abating, but he also pointed out that it is unlikely a placebo response could have been maintained for two years.
Side effects included tremulous voice and shortness of breath, both tolerable and receding over time.
The pilot study data was enough for European and Canadian authorities to approve VNS for treatment of depression. A 240-patient double blind study (in which half the devices were switched on and the other half left off) is nearing completion, and the results could lead to FDA approval in early 2002. The FDA has VNS on a fast track review process. Dr George is cautious about raising false hopes, noting "the scientist in me is skeptical until we receive double blind data."
The VNS device was invented by Jake Zabara PhD, a retired neurophysiologist at Temple University, who found that the vagus nerve transmitted signals up to the brain rather than down to the body as once thought. The device has now been implanted in 15,000 epilepsy patients worldwide. Cyberonics keeps a long-term patient data registry, and one interesting statistic from that registry is that even the nonresponders (still on their meds) show quality-of-life improvements such as alertness and better memory. Since many bipolar patients use these same meds, this raises the possibility that VNS could be used to reduce the sedating side effects of those drugs.
Cyberonics is also sponsoring studies of VNS for the treatment of Alzheimer's, anxiety, and obesity.
The battery in the device lasts about five years. The implant surgery is an outpatient procedure lasting about an hour. The patient can adjust the device with a magnet, and the doctor can make corrections with a wand attached to a computer. Robert Cummins, CEO of Cyberonics, foresees a day when settings can be fine-tuned based on a patient’s fMRI. "We have only begun to scratch the surface," he said.
The device, including surgery, can cost up to $20,000, but the company has funded a study about to be published in the Journal of Clinical Psychiatry showing that a patient who has had either two failed treatments, a suicide attempt, or a hospitalization will incur costs of $41,000 a year over the next five years. For a chronically depressed patient who has not been hospitalized, the cost is $9,000 a year. Those kind of numbers make it likely that health care providers will pick up the tab for the treatment.
The double-blind study results are expected to be announced at the end of February.
poster:Nickengland
thread:478884
URL: http://www.dr-bob.org/babble/20050404/msgs/479593.html