Found another good and more recent article on ONS.

From the website: docguide.com

Occipital-Nerve Stimulation More Effective Than Medical Management in Patients With Chronic Intractable Migraine: Presented at AAPM

By Emma Hitt, PhD

HONOLULU -- January 30, 2009 -- Occipital nerve stimulation (ONS) may be more effective than medical management in patients with intractable migraine headaches, according to findings from the first randomized trial of ONS in this setting.

According to the researchers, led by Joel Saper, MD, Michigan Head Pain and Neurological Institute, Ann Arbor, Michigan, 3% to 14% of patients with episodic migraine develop chronic migraine characterized by headache for more than 15 days per month.

To evaluate the efficacy of ONS versus medical management, Dr. Saper and colleagues conducted a multicentre, prospective, randomized, single-blind, controlled-feasibility study with a total of 110 patients with intractable chronic migraine according to International Classification of Headache Disorders criteria.

Subjects received diagnostic occipital nerve blocks, and responders were randomized in a 2:1:1 ratio into 3 treatment arms: adjustable stimulation (AS), preset stimulation (PS), and medical management. The first 8 who failed the block formed an ancillary group and also were offered ONS treatment.

Of the total group, 66 completed migraine diaries during the 3 months of follow-up. These patients had regularly experienced 15 or more headache days per month that were not responsive to conventional medical therapies.

At 3 months, the AS group showed a 27% reduction in headache days per month from baseline, the PS stimulation group showed a reduction of 8.8% (P = .132 against AS), and for medical management it was 4.4% (P = .058 against AS).

With respect to overall pain intensity, AS showed a 1.5% decrease from baseline, medical management showed a 0.6% reduction from baseline (P = .092 compared with AS), while PS showed a 0.5% decrease (P = .076 against AS). In addition, the overall pain intensity decrease was 39% with adjustable ONS and 0% with medical management (P = .003).

Rates of response at 3 months were 39% for AS, 6% for PS (P = .032 against AS), and 0% for MM (P = .003 against AS), and 40%.

No unexpected adverse events were noted. Lead migration occurred in 12 of 51 (24%) subjects. The most frequently reported non-device related event was worsened migraine. Occipital nerve block response did not appear to be predictive of response to ONS.

"Since lead migration was a common AE we must attempt to improve on the implanting technique," Dr. Saper said in an interview.

"Improvement and downsizing of the stimulator and battery pack are among the technology improvements needed," he added.

"Over time, if this looks like a viable and practical treatment, we will develop criteria in the guidelines of care," Dr. Saper said.

"The findings thus far are encouraging, and we hope that this approach will be available and effective for our most challenging cases. More studies, though, are necessary to determine overall efficacy and safety," he added.

Funding for the study was provided by Medtronics.

[Presentation title: Occipital Nerve Stimulation (ONS) for Treatment of Intractable Migraine Headache: 3-Month Results From the ONSTIM Feasibility Study. Abstract 155]