Modulation of motor cortex excitability in obsessive-compulsive disorder: an exploratory study on the relations of neurophysiology measures with clinical outcome.
Low-frequency repetitive transcranial magnetic stimulation (rTMS) to supplementary motor area (SMA) showed clinical benefit in obsessive-compulsive disorder (OCD). Here we tested whether clinical improvement was associated with enhanced cortical inhibition as measured by single and paired-pulse TMS variables. In 18 OCD patients receiving 4 weeks of either active or sham rTMS in a double-blind randomized trial, we assessed bilateral resting and active motor thresholds (RMT and AMT), cortical silent period (CSP), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). We tested correlations between changes in Yale-Brown Obsessive Compulsive Scale-Self-report (Y-BOCS-SR), Clinical Global Impression-Severity subscale (CGI-S) and cortical excitability measures. Active rTMS increased right hemisphere RMT whose change correlated with Y-BOCS-SR improvement. Baseline RMT hemispheric asymmetry, defined as the difference between left and right hemispheres RMT, and its normalization after active rTMS correlated with Y-BOCS-SR and CGI-S improvements. Active rTMS also increased right hemisphere SICI whose change correlated with Y-BOCS-SR and CGI-S at week 4, and with normalization of baseline RMT hemispheric asymmetry. Treatment-induced changes in cortical excitability measures are consistent with an inhibitory action of SMA rTMS on dysfunctional motor circuits in OCD. Correlations of neurophysiology measures with therapeutic outcome are supportive of the role of SMA in the modulation of OCD symptoms.
Division of Experimental Therapeutics, Department of Psychiatry, Columbia University/New York State Psychiatric Institute, New York, NY, USA; Division of Psychiatry, Department of Neuroscience, Siena University, Siena, Italy. Electronic address: am2518@columbia.edu.
Antonio
A
Mantovani
Simone
S
Rossi
Bruce D
BD
Bassi
Helen B
HB
Simpson
Brian A
BA
Fallon
Sarah H
SH
Lisanby
D000328:Adult; D000368:Aged; D002540:Cerebral Cortex / Q000503:physiopathology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009482:Neurophysiology; D009771:Obsessive-Compulsive Disorder / Q000503:physiopathology / Q000523:psychology* / Q000628:therapy*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D016896:Treatment Outcome
Cortical silent period; Intracortical facilitation; Motor threshold; Obsessive-compulsive disorder; Short-interval intracortical inhibition; Supplementary motor area; Transcranial magnetic stimulation