Summary of Evidence for Transcranial Magnetic Stimulation (TMS) for the Treatment of Obsessive-Compulsive Disorder (OCD)
Background
Transcranial Magnetic Stimulation (TMS) is a non-invasive treatment that uses pulsed magnetic fields to induce an electric current in a localized region of the cerebral cortex. An electromagnetic coil placed on the scalp induces focal, patterned current in the brain that temporarily modulates cerebral cortical function. Capacitor discharge provides electrical current in alternating on/off pulses. Stimulation parameters may be adjusted to alter the excitability of the targeted structures in specific cortical regions. TMS parameters include cranial location, stimulation frequency, pattern, duration, intensity, and the state of the brain under the coil.1
Systematic Review/Meta-Analysis (SR/MA)
A number of SR/MA2-16 conclude rTMS demonstrates a range from none to modest effect on the reduction of OCD symptoms but further research is required to determine optimal frequency, total pulses per session, and duration of treatment.
Two recent meta-analyses reviewed rTMS for the treatment of OCD. Ma et al12 reviewed 9 randomized controlled trials (RCTs) with 290 subjects with OCD. Most were selective serotonin reuptake inhibitor (SSRI) resistant. Using undescribed random assignment, 154 were in the active rTMS group and 136 to sham rTMS group. Primary outcome was Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores and secondary outcome was response rate determined by the RCT’s definition. Study size ranged from 18 to 65. The Y-BOCSs showed improvement when rTMS was added to treatment with medication. There were 9 subjects in 2 studies that did not have SSRI-resistant OCD, but the improvement continued to be shown when these RCTs were excluded from the Y-BCOS analysis. Actual Y-BCOS scores were not provided. It was noted that the active rTMS patients had higher baseline Y-BOSC scores, but numbers were not provided. Response rates were available for 8 of the 9 trials. Fifty-five of 139 active patients (39.6%) and 27 of the 122 sham patients (22.1%) responded. There was no difference in the drop-out rate between the active 8/207 (3.8%) and sham 7/94 (7.4%) subjects. Mean duration of rTMS treatment was 3.8 weeks with a range of 2 to 6 weeks. A sub-group analysis suggested treatment effects were larger at ‘2- and 6- weeks’ duration, but lack of data in most of the included studies at 4 weeks’ length may preclude accurate assessment. Additional limitations include stimulus parameters and follow-up data was not reported. The authors noted that future large–scale studies are needed to assess the long-term effect of rTMS as augmentation and mono-therapy for OCD. No conflicts of interest were reported.
Rehn et al13 conducted a SR and MA of rTMS used to treat OCD and focused on whether certain TMS parameters were associated with higher treatment effectiveness. Eighteen RCTs were included, 6 of which were also included in the Ma et al. study.12 Selected studies had patients ages 18-75 years with DSM-IV diagnosis of OCD; had randomized rTMS or sham treatment with either single- or double-blinding or parallel or cross-over design; more than 5 OCD subjects per arm; low-frequency (LF)(</= 1 Hz) or high-frequency (HF)-rTMS (>/=5 Hz) for >/= 5 sessions either as mono- or augmentation strategy; and pre- and post- reporting of Y-BOCS scores. Studies were excluded if patients were starting a new medication at the same time of rTMS. Total number of subjects was 484 with 262 receiving active rTMS and 222 sham rTMS. Study size ranged from 18 to 46. All trials used rTMS as an augmentation therapy with most of the patients having some degree of treatment resistance. The last Y-BOCS measurement obtained was used as the post-treatment score. Pre-and post-treatment Y-BOCS were available from each of the 18 studies, but the actual scores were not provided. Overall, active rTMS was significantly superior to sham rTMS. Cortical targets over the bilateral dorsolateral prefrontal cortex (B-DLPFC), right dorsolateral prefrontal cortex (R-DLPFC), and the supplementary motor area (SMA) yielded significantly superior Y-BOCS scores over sham treatments. Active rTMS directed at the L-DLPFC was not significantly improved over sham rTMS. Six trials had Y-BOCS scores at 4 weeks or less post-treatment and 3 had scores 12 weeks post-treatment. Improvements in scores were maintained. The authors stated that the clinical utility of rTMS in the treatment of OCD requires further investigation to discern the most optimal stimulation parameters. No conflicts of interest were reported.
Lusicic et al17 performed a systematic review on the effect of rTMS and dTMS on different brain targets in OCD. Twenty studies met inclusion criteria with 19 using rTMS and 1 using dTMS. All but 1 of the rTMS trials are included in the meta-analyses described above. Included brain areas were the dorsolateral prefrontal cortex (DLPFC), supplementary motor area (SMA), orbitofrontal/medial prefrontal cortex (OFC), and anterior cingulate cortex (ACC). Frequency stimulation was low (1 Hz) or high (>/=5 Hz). Treatment duration varied from 2 to 6 weeks with follow-up ranging from none to 3 months. Of 16 studies evaluated, 9 had Y-BOCS score reductions with rTMS versus sham while 8 showed no significant difference. The authors concluded treatment of OCD with neurostimulation shows promise, but it is yet to be determined how best to optimize the approach using rTMS or dTMS to achieve clinically relevant results.
Randomized Control Trials
RCTs comprised of 30 or fewer subjects were not included in this summary.
Carmi18 studied 41 OCD patients who had failed 2 SRI trials plus cognitive behavioral therapy (CBT). Baseline clinical and electrophysiological measurements, a 5-week treatment, and a 1-month follow-up were reported. The medial prefrontal cortex (mPFC) and the anterior cruciate cortex (ACC) were targeted. Entrance criteria included an age range of 18-65 years old; a DSM-IV diagnosis of OCD; a score of >/=20 on the Y-BOCS; stable SSRI medications for 8 weeks prior to enrollment and unchanged during treatment; and CBT at maintenance phase (if conducted). Exclusion criteria included any other Axis-I psychopathology or a current depressive episode. Randomization to treatment with 1 Hz (LF), 20 Hz (HF) or sham occurred using a computer program. Treatment occurred 5 times per week for 5 weeks. Primary and secondary outcomes were Y-BOCS and Clinical Global Impressions of Severity (CGI-S) which were obtained pre-treatment, prior to the second treatment session in weeks 2 to 4, prior to the last treatment session (post-treatment) and at 1-week and 1-month follow-up beginning with an exposure to personalized obsessive-compulsive cues.
Electroencephalograms (EEGs) during a Stroop task were performed at pre- and post-treatment time-points and analyzed by the condition (congruent or non-congruent) and whether the response was correct or a mistake. Most of the mistakes (93%) were made under incongruent conditions. Individuals who made more than 90% mistakes were excluded from analysis (2 HF and 3 sham). Error-related negativity (ERN) showed an increase in the HF group and a decrease in the sham group with treatment. (An ERN occurs when an individual makes a behavioral error.)
The baseline characteristics of the 3 groups did not differ. Three of the 41 participants dropped out, 1 in the sham group due to schedule conflicts and 2 from the HF group due to inconvenience. No adverse events occurred beyond headache in 3 from the HF group and 1 from sham. Asked to guess the group to which they were assigned, 75% of the LF, 88% of the HF, and 86% indicated they did not know. An interim analysis revealed a near significant effect for HF but not LF. Although no trend was reported in the group and 2 of the 8 had a worsening Y-BOCS score the LF arm of the study was omitted. Completion by 16 HF and 14 sham participants occurred. The percent change in Y-BOCS scores was significant at weeks 4 and 5 and a higher proportion of the HF group compared to the sham group (7/16 vs 1/14) reached the predefined response rate (30%) after 5 weeks. Using the more restrictive criterion of 35%, 5/16 HF and 1/14 sham individuals achieved the higher rate. Significant differences at 1 week occurred but not at 1 month follow-up. Similarly, the CGI-I results were significant after treatment and 1 week but not at 4 weeks.
The authors concluded the study showed the treatment was safe and effective immediately after treatment but not significant 4 weeks later. Limitations were noted to be that the study was considered as a pilot and had a small number of subjects; the provocation was not controlled, and the number of pulses differed for the HF and LF groups. A need for further studies was noted. A financial disclosure noted 1 of the authors is a co-inventor of the TMS H-coils, serves as a consultant for, and has financial interests in Brainsway and the study was partially supported by Brainsway, which produces the deep TMS H-coil systems.
A second study by Carmi et al19 was a prospective multicenter randomized double-blind placebo-controlled trial following the pilot described immediately above. One hundred patients with OCD and Y-BOCS score >/= 20 between the ages of 22-68 receiving treatment in an outpatient setting were recruited. Subjects were on a therapeutic dosage of a serotonin uptake inhibitor (SRI) for at least 2 months with limited response; or if not on an SRI, in CBT maintenance therapy with failure to respond adequately. Medications to treat depression were allowed but could not be changed for at least 2 months before enrollment. Exclusion criteria were any primary Axis I disorder other than OCD, severe neurological impairment, and any condition associated with an increased risk for seizures. Patients were randomized 1:1 into an active dTMS or sham group. A 3 to 5-minute individualized symptom provocation occurred before each treatment session. The medial prefrontal cortex and anterior cingulate cortex were targeted with 20 Hz dTMS. Patients, operators, and raters were blinded to treatment group. Subjects were queried regarding the group to which they had been assigned after the first treatment with 66% of the active and 69% of the sham group giving an incorrect answer. The treatment phase lasted 6 weeks with 1 day for assessment and had 3 phases – a 3-week screening phase, a 6-week treatment of 5 treatments per week, and a 4-week follow-up phase.
The primary outcome measure was a change in Y-BOCS score from baseline to post-treatment. A full response was defined as a >/=30% reduction and a partial response as >/=20%. At 6 weeks post-treatment, the Y-BOCS score significantly decreased in each group with the treatment group considered to have a statistically significant slope of change. At 4 weeks post-treatment, the treatment group had a statistically significant change in full response but not in the partial response rate. Clinical Global Impression Severity scales (CGI-S) and a modified version of the improvement scale (CGS-I) measurements were made post-treatment. The CGI-I scores were divided into improved (moderately to very much improved) and not improved (minimally to not improved). The active group had 20/41 (49%) compared to 9/43 (21%) reporting feeling moderate to “very much improved’ (P=0.011). The CGS-S scores also showed a significant difference in the treatment group post-treatment. No significant differences between groups were found for the Sheehan Disability Scale or the Hamilton Depression Rating Scale (HAM-D) scores. The drop-out rate was around 12% for each group (6/48 and 6/51). Adverse event rates did not differ between groups. One patient reported suicidal ideation (which was unreported and present before study entry) requiring inpatient treatment after 2 active dTMS treatments.
Limitations noted by the authors were that the provocations were uncontrolled and functional brain imaging of the mPFC and ACC was not performed. A different mechanism for dTMS compared to pharmaceuticals and CBT was suggested as well as the need to determine which patients might respond to dTMS. Further studies were recommended. Twelve of the 14 authors reported some financial relationship with Brainsway.
Elbeh et al20 performed a double-blind randomized trial to evaluate the impact of different frequencies of rTMS over right dorsolateral prefrontal cortex (DLPFC) in OCD. Forty-five subjects with OCD were enrolled and evaluated using: Yale-Brown obsessive-compulsive scale (Y-BOCS), Hamilton Anxiety Rating Scale (HAM-A), and Clinical Global Impression-Severity scale (CGI-S). They were randomized into 1 of 3 groups: 1st group received 1 Hz rTMS; 2nd group received 10 Hz rTMS; and 3rd group received sham stimulation all at 100% of the resting motor threshold for 10 sessions. Follow up assessment were after the final treatment and 3 months later. The group receiving 1 Hz versus 10 Hz groups showed a significant improvement in Y-BOCS and HAM-A scores (P<0.001 and 0.0001 respectively) and significantly larger percentage change in GCI-S, as well as greater clinical benefit than the 10 Hz. The authors conclude that 1 Hz-rTMS, targeting right DLPFC is a promising tool for treatment of OCD.
Dutta et al21 conducted a randomized placebo-controlled study to evaluate the effect of novel continuous Theta Burst Stimulation (cTBS) targeting OFC in OCD subjects. Thirty-three patients were randomly allocated to active cTBS (n= 18) or sham (n= 15). Each subject received 10 TBS sessions, 2 per day (total of 1200 pulses: intensive protocol) for 5 days in a week. The Y-BOCS, HAM-D, HAM-A, CGI-S scores were assessed at baseline, after last session and at 2 weeks post-rTMS. They reported a significant improvement from pretreatment to 2-weeks post TBS for obsessions, compulsions, HAM-A, HAM-D, and CGI scores, but when controlled for confounding variables, only HAM-A scores and CGI retained statistical significance. The authors conclude that intensive OFC cTBS (iOFcTBS) in OCD results in clinically significant improvements in anxiety symptoms and global severity, while acknowledging that improvement in anxiety symptoms could be due to “modulations of state dependent dysregulation in OCD.”
Badawy et al22 reported on 60 OCD patients to evaluate rTMS as monotherapy vs. add-on treatment in patients with poor response to SSRIs. Of 40 un-medicated patients, 20 received sham treatment and 20 TMS. An additional 20 patients with poor response to SSRI received rTMS. With 2-to-4-week follow-up they found TMS was not effective as monotherapy but was useful as add-on therapy. Study was limited by lack of control for the poor responder group, short follow-up, and small sample size. The authors conclude further studies regarding the site of stimulation, frequency and rate of stimulation, and the number of sessions is needed.
Society Guidance/Technology Analysis
- NICE Guidance23-Transcranial magnetic stimulation for obsessive-compulsive disorder. Recommendations conclude that evidence on the safety of transcranial magnetic stimulation for obsessive-compulsive disorder raises no major safety concerns. However, evidence on its efficacy is inadequate in quantity and quality. Therefore, this procedure should only be used in the context of research.
- UpToDate24 - Technique for performing transcranial magnetic stimulation (TMS) mentions for use in patients with major depression. There was no mention of TMS for OCD.
- ECRI25- Transcranial Magnetic Stimulation for Treating Adults with Obsessive-compulsive Disorder executive summary evidence was inconclusive based on too few data on outcomes of interest.
Contractor advisory committee (CAC) Meeting Summary
WPS co-hosted a CAC Meeting with multiple other contractors on 9/29/2021. The panelist reviewed the literature that was submitted as part of an LCD reconsideration request to expand the policy to include coverage for OCD. The panel shared the lack of good treatment options for refractory OCD and a priority to develop new and effective treatments. The literature was reviewed and noted to be challenged by small sample sizes, high risk of bias, many studies with lower quality study design (lack of control arm/blinding), short follow-up (4-5 weeks for most studies) with lack of long-term outcome data, and lack of real-world application of the technology. There was a discussion of risk of co-morbid depression and OCD and different coil locations with some potential overlap so brought up the potential impact of treatment for both conditions. One paper reviewed low vs. high frequency showing improvement with high frequency but not low. Another challenge addressed was which region of the brain should be targeted for OCD as the studies varied in the location treated. The panelist felt that there was not clarity regarding the degree of improvement in scores that would result in meaningful clinical improvement, but even small change would be significant in refractory OCD. In the study on predictors to response the panel did consider the secondary analysis that those with more severe disease had greater response to treatment. Overall, the panel felt there was potential improvement for OCD with TMS and it appears to be safe, but limitations in literature are substantial as described.
