Resting state eyes-closed cortical rhythms in patients with locked-in-syndrome: an EEG study.
OBJECTIVE
Locked-in syndrome (LIS) is a state of complete paralysis, except for ocular movements, which results from ventral brainstem lesions. Patients typically are fully conscious. Here we tested the hypothesis that electroencephalographic (EEG) rhythms are abnormal in LIS patients, possibly due to an impaired neural synchronization between brainstem and cerebral cortex.


METHODS
Resting state eyes-closed EEG data were recorded in 13 LIS subjects and 15 cognitively normal control subjects. With reference to the individual alpha frequency (IAF), the bands of interest were delta (IAF-8 to IAF-6Hz), theta (IAF-6 to IAF-4Hz), alpha 1 (IAF-4 to IAF-2Hz), alpha 2 (IAF-2 to IAFHz), and alpha 3 (IAF to IAF+2Hz). Furthermore, beta 1 (13-20Hz) and beta 2 (20-30Hz) bands were also considered. Cortical EEG sources were estimated by low-resolution electromagnetic tomography (LORETA).


RESULTS
The power of alpha 2 and alpha 3 sources in all regions was lower in patients with LIS compared to controls. The power of delta sources in central, parietal, occipital and temporal regions was higher in patients with LIS compared to controls.


CONCLUSIONS
These results suggest that cortical sources of resting state eyes-closed alpha and delta rhythms are abnormal in LIS patients.


CONCLUSIONS
LIS is accompanied by a functional impairment of cortical neuronal synchronization mechanisms in the resting state condition.
Babiloni
Claudio
C
Department of Biomedical Sciences, University of Foggia, Italy; Department of Imaging, SAN RAFFAELE Cassino, Italy.
Pistoia
Francesca
F
Sarà
Marco
M
Vecchio
Fabrizio
F
Buffo
Paola
P
Conson
Massimiliano
M
Onorati
Paolo
P
Albertini
Giorgio
G
Rossini
Paolo Maria
PM
D000328:Adult; D000368:Aged; D000513:Alpha Rhythm / Q000379:methods; D001931:Brain Mapping / Q000379:methods; D001933:Brain Stem / Q000503:physiopathology; D002540:Cerebral Cortex / Q000502:physiology*; D003700:Delta Rhythm / Q000379:methods; D004569:Electroencephalography / Q000379:methods*; D005123:Eye; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011782:Quadriplegia / Q000175:diagnosis / Q000503:physiopathology*; D012146:Rest / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology*