OA
American Journal of Psychiatry Research & Reviews
Fifty Percent or more Incremental Rise in Resting Motor Threshold of the Brain Emerging as an Early Critical Biomarker in Predicting the Success of rTMS Therapy in Treatment Resistant Obsessive Compulsive Disorder: A Case Series Based Pilot Study
Authors: Praveen Khairkar, MD, Anurag A, MD, Divya Chadhha, MD, Rajesh Khairkar, M.Tech, Sajjan Raina MBBS, Rajesh Khoiwal, MD, DNB*, Dheeraj Jain
Publication Year: 2026
Abstract
Objectives:
This pilot study aimed to evaluate whether a 50% or greater rise in Resting Motor Threshold can serve as a critical biomarker to predict the success of repetitive Transcranial Magnetic Stimulation in treatment-resistant Obsessive-Compulsive Disorder patients.
Methods:
Conducted at our advanced Neuromodulation laboratory in a tertiary care hospital, this case series-based pilot study involved 5 patients diagnosed with treatment-resistant OCD. Each underwent 12 to 18 sessions of rTMS targeting the supplementary motor area (1 Hz, 110% MT, 900 Pulses), anterior cingulate gyrus (20Hz, 100%MT, 2000 Pulses) and dorsomedial prefrontal cortex protocol (20 Hz, 100% MT, 750 Pulses). RMT was measured at baseline, after 10 sessions, and post-12 sessions, and then followed up at 3, 6, and 9 months. The clinical progress was assessed using standard OCD scales and correlated with RMT trajectory to evaluate predictive validity.
Results:
All three patients demonstrated a consistent rise in RMT by more than 50% viz: from 37% to 57% in case 1, from 32% to 53% in case 2, and from 42% to 63% in case 3 by the 12th rTMS session, aligning with significant symptomatic relief. Their MT values remained stable during remission over 12 months, reinforcing the link between early RMT elevation and sustained therapeutic benefit. This trend indicates that a more than 50% RMT rise post-initial rTMS targeted neural network sessions may signal a positive treatment trajectory in resistant OCD cases. 2 other cases where rTMS failed showed only minimal shift of RMT from 32% to only 37% at the end of 30 sessions in 4th Case while in 5th Case of failed rTMS showed 34% RMT baseline increased only to 38% after 30 sessions.
Conclusion:
To our knowledge, this is the first study in literature elucidating a 50% or greater rise in RMT as a reliable and early biomarker for successful rTMS response in treatment-resistant OCD. This finding although supports its potential role in guiding personalized, precision-based neuromodulation strategies for enhanced treatment outcomes, would require further large scale replication and validation.