Cortical sources of resting-state alpha rhythms are abnormal in persistent vegetative state patients.
OBJECTIVE
High power of pre-stimulus cortical alpha rhythms (about 8-12 Hz) underlies conscious perception in normal subjects. Here we tested the hypothesis that these rhythms are abnormal in persistent vegetative state (PVS) patients, who are awake but not aware of self and environment.


METHODS
Clinical and resting-state, eyes-closed electroencephalographic (EEG) data were taken from a clinical archive. These data were recorded in 50 PVS subjects (level of cognitive functioning--LCF score: I-II) and in 30 cognitively normal subjects. Rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). Cortical sources were estimated by low-resolution electromagnetic tomography (LORETA). Based on LCF score at 3-months follow-up, PVS patients were retrospectively divided into three groups: 30 subjects who did not recover (NON-REC patients; follow-up LCF: I-II), 8 subjects classified as minimally conscious state patients (MCS patients; follow-up LCF: III-IV), and 12 subjects who recovered (REC patients; follow-up LCF: V-VIII).


RESULTS
Occipital source power of alpha 1 and alpha 2 was high in normal subjects, low in REC patients, and practically null in NON-REC patients. A Cox regression analysis showed that the power of alpha source predicted the rate of the follow up recovery, namely the higher its power, the higher the chance to recover consciousness. Furthermore, the MCS patients showed intermediate values of occipital alpha source power between REC and NON-REC patients.


CONCLUSIONS
These results suggest that cortical sources of alpha rhythms are related to the chance of recovery at a 3-months follow-up in patients in persistent vegetative state.


CONCLUSIONS
Cortical sources of resting alpha rhythms might predict recovery in PVS patients.
Babiloni
Claudio
C
Department of Biomedical Sciences, University of Foggia, V.le Pinto 1, 71100 Foggia, Italy. c.babiloni@unifg.it
Sarà
Marco
M
Vecchio
Fabrizio
F
Pistoia
Francesca
F
Sebastiano
Fabio
F
Onorati
Paolo
P
Albertini
Giorgio
G
Pasqualetti
Patrizio
P
Cibelli
Giuseppe
G
Buffo
Paola
P
Rossini
Paolo Maria
PM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000513:Alpha Rhythm; D000704:Analysis of Variance; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000473:pathology / Q000503:physiopathology*; D012044:Regression Analysis; D013057:Spectrum Analysis; D055815:Young Adult