Motor cortical excitability in obsessive-compulsive disorder: Transcranial magnetic stimulation study.

OBJECTIVES: Transcranial magnetic stimulation is a non-invasive method of stimulating the brain that is increasingly being used in neuropsychiatric research. Previous work has suggested that the pathophysiology of obsessive-compulsive disorder (OCD) may involve dysfunction of excitatory and/or inhibitory brain function. This study aimed to extend those findings. METHODS: The study included 45 OCD patients and 15 age- and sex-matched healthy volunteers. Clinical evaluation was conducted using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Hamilton Anxiety Rating Scale (HAM-A), and Clinical Global Impression rating scale (CGI). Physiological measures were resting and active motor thresholds (RMT and AMT), motor evoked potential (MEP) amplitude, cortical silent period (CSP) and transcallosal inhibition (TCI) durations, short-interval intracortical inhibition (SICI), and intracortical facilitation. RESULTS: RMT and AMT were significantly lower in patients than in the control group. The mean duration of the CSP and TCI were also significantly shorter. Obsessive trait was associated with significant reduction of TCI duration compared to compulsive trait. There was significant reduction in SICI in OCD patients compared to controls. There were no significant correlations between the Y-BOCS, HAM-A and CGI scores and the cortical excitability parameters. CONCLUSION: These results provide further evidence for inhibitory deficits or increased facilitation in cortical circuits of patients with OCD.

Transcranial magnetic stimulation identifies cortical excitability changes in monosymptomatic nocturnal enuresis.

OBJECTIVES: A limited number of electroencephalography (EEG) studies in nocturnal enuresis (NE) have reported cortical dysmaturity. The aim of the present study was to test this notion by examining cortical excitability in subjects with nocturnal enuresis (NE) using transcranial magnetic stimulation (TMS). MATERIAL AND METHODS: We investigated 41 patients with NE meeting the DSM-IV diagnostic criteria for NE, and 18 age- and sex-matched controls. Each subject was assessed clinically regarding frequency, duration of enuresis and Health Survey Measurement. Neurophysiological measures included resting and active motor thresholds (RMT, AMT), motor evoked potentials (MEP) of upper and lower limbs, cortical silent period duration (CSP) and transcallosal inhibition (TCI), in the upper limbs. RESULTS: Patients had a significantly lower Health Survey Measurement score for both physical and mental health components compared to the control group. RMT and AMT of both upper and lower limbs as well as the duration of the CSP and TCI were significantly reduced compared with the control group. There was significant positive correlation between RMT, AMT and Health Survey Measurement scores, especially Social Functioning. CONCLUSION: Patients with nocturnal enuresis are characterized by pathologically increased excitability and reduced inhibitory processing in the motor cortex, which could contribute to the pathogenesis of nocturnal enuresis.