Originally posted 12/31/2012
Today I read about the stereotactic brain surgery used to treat opioid dependence in China over the past ten years. The procedure is relatively straightforward; the patient’s skull is clamped in place while small holes are drilled, guided by computerized, 3-dimensional maps of the brain. Probes are inserted deeply through brain tissue to the nucleus accumbens, where electric current destroys varying amounts of brain tissue. Patients are awake and talking during the procedure, so that surgeons know if the probes are too close to brain regions that control speech or other functions.
A large number of ablations for the treatment of addiction were performed in China about ten years ago. The rapid growth in popularity of the technique, before full knowledge of the risks and long-term effects, led to a ban on the procedures by the Chinese Ministry of Health in 2004. Still, ablations were performed as part of research studies, with over 1000 people treated by ablation since 2004.
The scientific community outside of China overwhelmingly condemns the technique, and medical journals are pressured to withhold publication of ablation studies. Human rights advocates claim that such experiments are performed on people who are not fully aware of the risks, or who are pressured to participate in the studies to avoid harsh punishments for drug offenses. The veracity of the results from ablation studies has also been challenged. Ablation treatment of opioid dependence is in the news lately because of a recent paper describing the five-year follow-up of opioid addicts treated by the procedure.
Neuroscientists distinguish between DBS (deep brain stimulation by electric current) vs. procedures where brain tissue is destroyed. I’m surprised by the intensity of the distinction, given the similarity of the procedures. In both cases long probes are passed through brain tissue, risking hemorrhage, stroke, or seizures. For DBS, wires are left behind and connected to power-packs that release different patterns of electrical current. In the ablation studies, small areas of tissue at the end of the probes are destroyed, and the probes removed. If there is a future for addiction treatment using stereotactic brain surgery, DBS is likely to become the procedure of choice, given the preference by the scientific community for non-permanent interventions.
The recent follow-up study found that about half of those treated by ablation of the nucleus accumbens were sober from heroin after five years. But about a quarter of the patients who had ablation were found to have long-term neuropsychiatric side effects including memory loss, loss of motivation, mood disturbances, and loss of sexual desire.
I found the studies and results interesting in a number of ways. Throughout the latest paper, the authors point out the severe consequences of opioid dependence and the lack of effective treatment options. Opioid dependence is noted to be a permanent, progressive, fatal condition, with a prognosis poor enough to warrant drilling holes in the skull and destroying brain tissue. Even as record numbers of young people die from overdose, I don’t have the sense that US citizens recognize the severity of the problem.
I find it interesting how strongly society’s perceptions influence what are considered appropriate or inappropriate brain procedures. SingularityHub points out the popularity of frontal lobotomies after 1949, when António Egas Moniz won the Nobel Prize for Physiology or Medicine for inventing the procedure. Over 20,000 lobotomies were performed in the US by 1951, but the procedure was discredited and eventually banned in the US. Who says the Nobel Prize people always get it right?
The recent study’s introduction points out that the most stringent addiction treatments in China– compulsory detoxification, mandatory labor, education, and skills training for as long as 3 years– have one-year abstinence rate of 44% and 3-year abstinence rates of only 15%.
Drilling holes deep into the brain to destroy the pleasure centers might bring the sobriety rates up to 50%, but at the cost of memory, motivation, and sex drive.
And then there is buprenorphine (brand name Suboxone), a medication that has success rates over 50%, with fewer risks or side effects than drilling holes in the brain– but that remains limited by US law.
Which approach would you prefer for your son or daughter?