Obsessive-compulsive disorder (OCD) is a chronic and often debilitating mental illness characterized by intrusive, irrational thoughts and repetitive behaviors.
For patients with severe, treatment-resistant OCD, surgical ablation of problematic brain regions may provide lasting relief when other therapies have failed.
A novel technique called magnetic resonance-guided focused ultrasound surgery (MRgFUS) is emerging as a promising ablative surgical option for OCD.
Key Facts:
- OCD afflicts 1-3% of the population and can severely impair quality of life.
- Standard treatments like medication and psychotherapy fail to adequately treat OCD in 10-30% of patients.
- Ablative neurosurgery for OCD has a long history of targeting areas like the anterior limb of the internal capsule.
- MRgFUS is a new, minimally-invasive ablation method that allows for precise, MRI-guided lesioning.
- Early results suggest MRgFUS capsulotomy is safe and effective for reducing OCD symptoms long-term.
- More research is needed, but MRgFUS could transform surgical options for severe, refractory OCD.
Source: Indian J Psychiatry 2019
The Agony of Treatment-Resistant OCD
OCD manifests in a wide range of obsessive thoughts and compulsive rituals that consume hours each day for those afflicted.
Sufferers commonly experience debilitating obsessions about contamination, doubts, symmetry/ordering, unacceptable thoughts, or harming others.
Compulsions like repetitive cleaning, checking, counting, or arranging typically provide only temporary relief from obsessive anxiety.
OCD usually begins gradually in adolescence or early adulthood and follows a chronic course.
Without proper treatment, OCD symptoms often worsen over time and can severely restrict work, academics, and relationships.
First-line treatments for OCD include cognitive-behavioral psychotherapy, specifically exposure and response prevention (ERP), and medications like SSRIs.
About 70% of patients respond well to initial therapy. However, 10-30% have severe, treatment-resistant OCD that persists even after multiple medications and psychotherapy.
For this substantial refractory group, OCD becomes a nightmare without end.
Non-stop rituals consume all free time, work ability declines, relationships crumble, and suicidal thoughts emerge.
When all else fails, these patients desperately need alternatives.
A Long History of Psychosurgery for OCD
The notion of “psychosurgery” – operating on the brain to treat mental illness – originated over a century ago.
Crude procedures like lobotomies were performed on psychiatric patients before modern standards of ethics and efficacy existed.
But along with negative outcomes, surgeons also serendipitously noticed OCD symptom improvement in some cases.
This sparked interest in ablative neurosurgery specifically targeting brain regions implicated in OCD.
Stereotactic ablation of areas like the anterior limb of the internal capsule (ALIC) and anterior cingulate cortex emerged as surgical options for OCD in the 1950s-60s.
Radiofrequency thermoablation and gamma knife radiosurgery have been used for decades to create lesions in these OCD-related areas.
Past ablative procedures reduced OCD symptoms in 30-60% of carefully selected patients. However, concerns remained about permanent side effects.
Thermal capsulotomy, for example, carries a ~20% risk of serious complications like apathy or incontinence.
The irreversibility and safety issues associated with traditional ablation prompted a shift towards deep brain stimulation (DBS) for OCD in recent years.
But DBS requires permanent implantation of electrodes/battery packs and provides inconsistent benefits.
MRgFUS: A Novel Form of Ablation
Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is an innovative ablation technique combining two key technologies:
- Highly focused ultrasound beams can deposit targeted thermal energy deep inside the brain without an incision.
- MRI allows precise, real-time monitoring of the ablation zone.
An MRI-compatible transducer helmet is placed over the shaved scalp.
Focused ultrasound waves penetrate the skull and convert to heat at the target site, producing a discrete thermal lesion.
Meanwhile, temperature-sensitive MRI confirms the location and extent of ablation.
MRgFUS can lesion tissue with sub-millimeter accuracy without ionizing radiation.
The thermal effects are visible in real time, before damage is done. This allows very controlled, customizable ablation of problematic brain regions.
Research on MRgFUS capsulotomy for OCD is still in early stages, but results are promising.
Studies report 35-50% Y-BOCS score decreases sustained over 2 years post-treatment. OCD symptoms tend to improve quickly, within 1 week.
Side effects like headache and nausea are generally mild.
Not only does MRgFUS offer lasting OCD relief for many, it also avoids implant-related complications with DBS.
The non-invasive, adjustable nature of MRgFUS aligns well with the goals of modern psychosurgery.
Patient Selection and Targeting
Patients with debilitating OCD symptoms for 5+ years who have exhausted medication, ERP, and other therapies without lasting improvement are considered for MRgFUS capsulotomy.
Candidates undergo psychiatric evaluation to confirm OCD diagnosis and severity.
Most MRgFUS psychosurgery, like previous ablation treatments, targets the anterior limb of the internal capsule (ALIC).
The ALIC contains white matter connections between subcortical nuclei and frontal regions that appear hyperactive in OCD.
Bilateral thermal lesions approximately 10mm long are placed 7mm anterior to the anterior commissure.
Multiple safeguards are implemented to avoid complications:
- Gradually increasing ablation temperatures and monitoring for changes
- Neurologic exams during the procedure
- Post-op inpatient monitoring
- Avoiding areas prone to damage like the fornix
With precise targeting and real-time feedback, MRgFUS empowers surgeons to pinpoint OCD circuitry while minimizing harm.
The Future of Psychosurgery for OCD
After falling out of favor decades ago, ablative neurosurgery is re-emerging as a last resort for patients crippled by OCD.
MRgFUS capsulotomy, though still experimental, could transform surgical options given its non-invasive nature and precision.
But many questions remain. Large, multi-center trials are needed to optimize targeting and protocols.
We must also deepen our understanding of how lesions translate to symptom changes, and for whom this invasive treatment is appropriate.
While not a first or second line therapy, MRgFUS capsulotomy brings new hope for those out of options.
With continued research, MRgFUS may offer life-changing relief to the most disabled OCD sufferers.
References
- Study: Magnetic resonance-guided focused ultrasound surgery for OCD: potential use as a novel ablative surgical technique
- Authors: Kyung Won Chang et al. (2019)
