The first trial in humans is now under way to explore the feasibility and safety of using MRI-guided focused ultrasound for the treatment of refractory depression. The first patient has already undergone the procedure.
"There is a need for noninvasive treatment options for patients with depression that cannot be managed through medication," lead investigator Jin Woo Chang, MD, at the Yonsei University College of Medicine in Seoul, South Korea, said in a statement.
"And we will continue to monitor the patient to assess how her depressive symptoms change over time."
For the pilot study, 10 patients with severe depression that is resistant to both medication and electroconvulsive therapy (ECT) will undergo the procedure using a noninvasive neurosurgery MRI system (InSightec's ExAblate Neuro system).
Efficacy will be measured during a 6-month follow-up period to see how well patients respond to the procedure.
Asked to explain how the MRI-guided, focused ultrasound procedure works, Rees Cosgrove, MD, head of epilepsy and functional neurosurgery at Brigham and Women's Hospital, Boston, Massachusetts, told Medscape Medical News that the procedure is exactly the same as the one used when treating essential tremor but that the target in the brain is different.
"Patients first have their head shaved. And they are stabilized in a frame and placed in the focused ultrasound machine inside an MRI scanner," he said.
The focused ultrasound machine then summates the energy of 1000 small ultrasound beams to create a lesion in the anterior limb of the internal capsule, a well-described target for the treatment of major depression.
"It's not that the anterior limb of the internal capsule is a focus for major depressive disorder," Dr Cosgrove said.
"But it's the same target that we've used for many years during thermal ablation, and the beauty of focused ultrasound is that you don't have to 'instrument' the brain — you don't have to open the head or make a hole in the skull; you don't have to pass an electrode down to the target ― but the target is the same, the size of the lesion is essentially the same, it's just the method of being able to do it doesn't impart any of the risk of open surgery, and it's painless," he added.
Much like ECT, investigators are not at all certain how the ablation of a small amount of tissue located deep inside the brain produces an antidepressant effect.
However, from empirical observation following capsulotomy using thermal ablation, mood and function slowly improve over time, even years, following the procedure.
"Patients actually do get an immediate sense of relief from anxiety, so the anxious depression goes away quite rapidly," said Dr Cosgrove. "But the real symptoms of depression and obsessive compulsive disorder take longer to resolve," he added.
"So there is this period of latency when treatment effects have not yet occurred, and you would maintain these kinds of patients on antidepressant medication anyway, as it's very rare that they would ever get off medication."
Using the same MRI-guided focused ultrasound technique resulted in gradual improvement in measures of OCD, anxiety, and depression during the a 6-month follow-up period.
In the earlier study, all four patients experienced an immediate and substantial improvement in measures of depression and anxiety.
There were no physical or neuropsychological side effects from the procedure, and there appeared to be no effect from focused ultrasound on neuropsychological test scores between baseline and 6-month follow-up.
"We don't yet know if there are any real downsides with focused ultrasound, but again, the beauty of this technique is that we can see the target we want to ablate on the MRI scan, so it's very unlikely that we are going to hit the wrong target," Dr Cosgrove said.
"So focused ultrasound is really a revolutionary technology that allows us to perform functional neurosurgery without any of the risk of instrumenting the human brain and without any of the risk of implanted electrodes or hardware."
The authors and Dr Cosgrove have reported no relevant financial relationships.
Focused Ultrasound Foundation. Press release
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Cite this: First Trial of Focused Ultrasound in Depression Under Way - Medscape - Sep 30, 2015.