Functional role of ipsilateral motor areas in multiple sclerosis

Daniel Zeller (1) , Su-Yin Dang (1) , Katja Stefan (1) , Armin Biller (2) , Andreas Bartsch (2) , Dorothee Saur (3) , Martin Bendszus (2) , Peter Rieckmann (4) , Klaus V Toyka (1) , Joseph Classen (3)

1 JMU - Julius-Maximilians-Universität Würzburg
2 Universität Heidelberg [Heidelberg] = Heidelberg University
3 Leipzig University / Universität Leipzig
4 Neurologische Klinik Bamberg

Background: In patients with multiple sclerosis (MS), motor tasks are associated with increased activation of ipsilateral motor cortical areas. We examined the role of two ipsilateral motor areas during performance of a simple motor task in MS-patients in relation to their motor impairment and CNS injury. Methods: Single pulses of transcranial magnetic stimulation (TMS) were used to interfere transiently with neuronal processing in the contralateral (M1CONTRA) or ipsilateral (M1IPSI) primary motor cortex or ipsilateral dorsal premotor cortex (PMdIPSI) during a simple reaction time (RT) task in 26 right-handed patients with moderately severe stable MS and matched healthy controls. Subjects responded to an auditorily presented Go signal as quickly as possible by performing isometric right thumb abductions. TMS was applied 100 msec after the Go signal. Motor impairment was evaluated by hand function tests. CNS injury was assessed by magnetic resonance spectroscopy (normalized N-acetyl-aspartate spectra, NAA/Cr), by the total cerebral T2-weighted MRI hyperintense lesion load, and by corticomuscular latency (CML) to the abductor pollicis brevis muscle. Results: TMS applied to M1CONTRA slowed RT in patients and controls. In contrast, stimulation of M1IPSI or PMdIPSI increased RT only in MS-patients. In patients, the relative RT changes following TMS over M1IPSI or PMdIPSI did neither correlate with any of the motor function tests, nor with NAA/Cr or total cerebral lesion load. However, RT changes following TMS over M1IPSI correlated inversely with CML. Conclusions: Recruitment of ipsilateral motor areas may be a functionally relevant, yet limited adaptive response to chronic brain injury in MS-patients.

Mots clés: MAGNETIC STIMULATION; MOTOR PHYSIOLOGY; MULTIPLE SCLEROSIS; REHABILITATION

Daniel Zeller, Su-Yin Dang, Katja Stefan, Armin Biller, Andreas Bartsch, et al.. Functional role of ipsilateral motor areas in multiple sclerosis. Journal of Neurology, Neurosurgery and Psychiatry, 2010, 82 (5), pp.578. ⟨10.1136/jnnp.2010.219964⟩. ⟨hal-00589429⟩