Cortical disinhibition in diabetic patients with neuropathic pain.
OBJECTIVE
Motor cortex disinhibition has a role in the mechanism of neuropathic pain. The duration of the cortical silent period (CSP) is used as a measure of excitability in cortical inhibitory circuits. We investigated cortical disinhibition in diabetic patients with and without neuropathic pain.


METHODS
We studied diabetic patients with (n = 20) and without (n = 50) neuropathic pain, and control subjects (n = 30). Transcranial magnetic stimulation (TMS) was performed on the right hemisphere at rest, and surface electromyography was recorded from the left first dorsal interosseous muscle for evaluation of motor evoked potential (MEP) latency and amplitude. CSP was recorded from the left FDI, and TMS was then delivered while the subject was performing a voluntary contraction.


RESULTS
We showed a low resting motor threshold, a short CSP duration, and a low CSP duration/MEP amplitude ratio in patients with neuropathic pain (P < 0.0001, P < 0.0001, P < 0.0001).


CONCLUSIONS
Our findings demonstrate that diabetic patients with neuropathic pain have a cortical disinhibition.
Turgut
N
N
Neurology Department, Trakya University School of Medicine, 22030 Edirne, Turkey. nildaturgut@hotmail.com
Altun
B U
BU
D000368:Aged; D000704:Analysis of Variance; D002540:Cerebral Cortex / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000503:physiopathology*; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology*; D009437:Neuralgia / Q000150:complications / Q000503:physiopathology*; D009460:Neurologic Examination; D010147:Pain Measurement; D050781:Transcranial Magnetic Stimulation