Abnormal plasticity of the sensorimotor cortex to slow repetitive transcranial magnetic stimulation in patients with writer's cramp

• Published in: Movement disorders Vol. 22; no. 1; pp. 81 - 90
• Main Authors: Bäumer, Tobias, Demiralay, Cüneyt, Hidding, Ute, Bikmullina, Rosalia, Helmich, Rick C., Wunderlich, Silke, Rothwell, John, Liepert, Joachim, Siebner, Hartwig R., Münchau, Alexander
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.01.2007; Wiley
• Subjects: Adult; Aged; Analysis of Variance; Biological and medical sciences; Brain Mapping; Dystonic Disorders - pathology; Dystonic Disorders - physiopathology; Electric Stimulation - methods; Female; Humans; Injuries of the nervous system and the skull. Diseases due to physical agents; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Imaging - methods; maladaptive plasticity; Male; Medical sciences; Middle Aged; Multiple sclerosis and variants. Guillain barré syndrome and other inflammatory polyneuropathies. Leukoencephalitis; Nervous system; Neural Inhibition - radiation effects; Neurology; Neuronal Plasticity - radiation effects; Psychophysics; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Reaction Time - drug effects; repetitive transcranial magnetic stimulation; Sensory Thresholds - radiation effects; short-latency afferent inhibition; Skin - innervation; somatosensory cortex; Somatosensory Cortex - physiopathology; Somatosensory Cortex - radiation effects; Transcranial Magnetic Stimulation; Traumas. Diseases due to physical agents; writer's cramp; Human; Nervous system diseases; maladaptive plasticity; Transcranial magnetic stimulation; Central nervous system; Encephalon; Somatosensory cortex; Writer cramp; Striated muscle disease; writer's cramp; Somesthetic pathway; Plasticity; Repetitive stimulus; Sensorimotor cortex; short-latency afferent inhibition; repetitive transcranial magnetic stimulation
• ISSN: 0885-3185; 1531-8257
• DOI: 10.1002/mds.21219

Previous studies demonstrated functional abnormalities in the somatosensory system, including a distorted functional organization of the somatosensory cortex (S1) in patients with writer's cramp. We tested the hypothesis that these functional alterations render S1 of these patients more susceptible to the “inhibitory” effects of subthreshold 1 Hz repetitive transcranial magnetic stimulation (rTMS) given to S1. Seven patients with writer's cramp and eight healthy subjects were studied. Patients also received rTMS to the motor cortex hand area (M1). As an outcome measure, short‐latency afferent inhibition (SAI) was tested. SAI was studied in the relaxed first dorsal interosseous muscle using conditioning electrical stimulation of the index finger and TMS pulses over the contralateral M1. Baseline SAI did not differ between groups. S1 but not M1 rTMS reduced SAI in patients. rTMS had no effects on SAI in healthy subjects. Because SAI is mediated predominantly at a cortical level in the sensorimotor cortex, we conclude that there is an abnormal responsiveness of this area to 1 Hz rTMS in writer's cramp, which may represent a trait toward maladaptive plasticity in the sensorimotor system in these patients. © 2006 Movement Disorder Society