Compensatory movement-related recruitment in amyotrophic lateral sclerosis patients with dominant upper motor neuron signs: an EEG source analysis study.
Cortical reorganization to simple movement in patients with amyotrophic lateral sclerosis (ALS) has been investigated in neuroimaging studies, reporting recruitment of ipsilateral primary sensorimotor (iSMC) and premotor regions (PMd). In order to investigate the spatiotemporal pattern of such overactivation, EEG source analysis to brisk self-paced finger movements was performed in thirty-two ALS patients, able to initiate their movement as fast as controls and clustered according to their most affected motor neuron (upper or lower). Reduced activity within cortical sources in bilateral SMC and caudal mesial areas was found only in patients subgroup with extensive upper motor neuron (UMN) clinical signs and mild motor weakness (U>L). Its absence in patients with opposite clinical features (L>U) suggest that this reduction might represent a possible marker of UMN impairment, and that the lower motor neuron (LMN) degeneration in L>U patients did not exert a retrograde effect over their cortical motor neurons. An ipsilateral premotor recruitment was observed in U>L patients only and since its extent positively correlated with movement initiation speed and right hand Medical Research Council (MRC) score, it might represent a compensatory recruitment. The latter correlation might suggest that the slight motor weakness in those patients may at least partly depend from a UMN dysfunction that can be compensated by cortical recruitment.
Dept. of Clinical Neurophysiology, Neurology, Neurorehabilitation, Experimental Neurology Institute, IRCCS San Raffaele, Via Olgettina 60, 20132 Milan, Italy.
Alberto
A
Inuggi
Nilo
N
Riva
Javier J
JJ
González-Rosa
Stefano
S
Amadio
Ninfa
N
Amato
Raffaella
R
Fazio
Ubaldo
U
Del Carro
Giancarlo
G
Comi
Letizia
L
Leocani
D000222:Adaptation, Physiological / Q000502:physiology*; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods*; D006225:Hand / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D011999:Recruitment, Neurophysiological / Q000502:physiology*