Limbic Paroxysmal Magnetoencephalographic Activity in 12 Obsessive-Compulsive Disorder Patients: A New Diagnostic Finding

Background: We describe frontotemporal paroxysmal rhythmic activity recorded by magnetoencephalography (MEG) in patients with obsessive-compulsive disorder (OCD).

Method: Twelve patients with OCD (per ICD-10 and DSM-IV criteria), aged 18 to 65 years, were assessed using MEG. Patients’ classification according to the Yale Brown OCD Scale was as follows: severe = 8, moderate = 3, and mild = 1. MEG findings were compared with those of 12 age- and sex-matched healthy subjects (control group) with no previous history of psychiatric or neurologic disorders. All study participants underwent neurologic and basic medical examinations, including magnetic resonance imaging, electrocardiograms (EEGs), and electrooculograms. The study was conducted between January 2001 and January 2002.

Results: Two types of MEG activity were observed in patients with OCD: (1) frontotemporal paroxysmal rhythmic activity with low-amplitude spikes (< 1 picoTesla) in 92% (11/12) of patients and (2) intermittent isolated spikes and sharp waves in all patients (12/12). The OCD group had paroxysmal rhythmic MEG activity in the cingulate cortex (12/12), insula (10/12), hippocampus (9/12), temporal superior gyrus and angular and supramarginal gyri (9/12), precentral and postcentral gyri (8/12), orbitofrontal cortex (5/12), and parietal lobes (5/12). MEG recordings were normal in the control group, and EEG findings were normal in both the OCD and control groups.

Conclusions: Frontotemporal paroxysmal rhythmic activity with a preferential limbic distribution is a sensitive MEG finding in patients with OCD. Although the pathophysiology of this abnormality remains unknown, a corticostriatal network dysfunction was hypothesized.