According to a study by Sandra G J Boccard, University of Oxford, Oxford, UK and colleagues, and published in Neurosurgery, deep brain stimulation patients with difficult-to-treat neuropathic pain can lead to long-term improvement in pain scores and other outcomes.
In the study it was demonstrated how some outcomes show continued improvement after the first year, which is one of the largest studies of deep brain stimulation for neuropathic pain performed to date.
The authors reviewed their 12-year experience with deep brain stimulation for neuropathic pain. Although deep brain stimulation has also been used to treat various types of chronic pain, its role in patients with neuropathic pain remains unclear.
Between 1999 and 2011, that authors’ programme evaluated 197 patients with chronic neuropathic pain for eligibility for deep brain stimulation. Of these, 85 patients proceeded to treatment. The patients who underwent deep brain stimulation were 60 men and 25 women, (average age 52 years). Stroke was the most common cause of neuropathic pain, followed by head and face pain, spinal disease, amputation, and injury to nerves from the brachial plexus.
In 74 patients, a trial of deep brain stimulation produced sufficient pain relief to proceed with implantation of an electrical pulse generator. Of 59 patients with sufficient follow-up data, 39 had significant improvement in their overall health status up to four years later. Thus, 66% of patients “gained benefit and efficacy” by undergoing deep brain stimulation, according to Boccard et al.
The benefits of deep brain stimulation varied for patients with different causes of neuropathic pain. Treatment was beneficial for 89% for patients with amputation and 70% of those with stroke, compared to 50% of those with brachial plexus injury.
On average, scores on a 10-point pain scale (with 10 indicating the most severe pain) decreased from about 8 to 4 within the first three months, remaining about the same with longer follow-up. Continued follow-up in a small number of patients suggested further improvement in other outcomes, including quality-of-life scores.
According to the authors, deep brain stimulation has been regarded as potentially useful for patients with severe neuropathic pain that is not relieved by other treatments. However, because of the difficulties of performing studies of this highly specialised treatment, there has been relatively little research to confirm its benefits; only about 1,500 patients have been treated worldwide. The new study—accounting for about 5% of all reported patients—used up-to-date deep brain stimulation technologies, imaging, and surgical techniques.
Boccard and others acknowledged the limitations of their study—especially the lack of complete patient follow-up. However, they said their experience is sufficiently encouraging to warrant additional studies, especially with continued advances in stimulation approaches and technology. They concluded: “Clinical trials retaining patients in long-term follow-up are desirable to confirm findings from prospectively assessed case series.”