Unravelling motor networks in patients with chronic disorders of consciousness: A promising minimally invasive approach.
Behavioral responsiveness and awareness levels correlate with the degree of functional connectivity within cortical-thalamocortical networks, whose breakdown accounts for chronic disorders of consciousness (DOC). Our study was aimed at assessing the role of the primary motor area (M1) and premotor-M1 circuitry dysfunction in motor output deterioration in minimally conscious state (MCS) and unresponsive wakefulness syndrome (UWS) patients. As a control group, we included a healthy subject (HC) sample in the study. We evaluated the effects of different types of transcranial magnetic stimuli over M1 by recording post-stimulus time histogram (PSTH), which includes a series of peaks of unit firing activity that match with D and I-waves, characterizing the descending corticospinal volleys evoked by transcranial magnetic stimuli. As compared to HC, DOC patients showed a dysfunction of intra-M1 and premotor-M1 circuits, which correlated with the Coma Recovery Scale-Revised scorings. Nonetheless, one UWS patient showed a partially preserved premotor-M1 circuitry, paralleled by a severe intra-M1 circuitry dysfunction. Our data suggest that motor unresponsiveness in some DOC patients may be due to a pure motor output failure, as in the functional locked-in syndrome (fLIS), rather than to a premotor-motor connectivity impairment, which instead characterizes MCS and UWS.
IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
Antonino
A
Naro
IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
Antonino
A
Leo
IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
Antonio
A
Buda
IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
Alfredo
A
Manuli
IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
Alessia
A
Bramanti
IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
Placido
P
Bramanti
IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy. Electronic address: salbro77@tiscali.it.
Rocco Salvatore
RS
Calabrò
D000328:Adult; D000368:Aged; D003244:Consciousness Disorders / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009046:Motor Neurons / Q000502:physiology; D011712:Pyramidal Tracts / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
Corticospinal tract; Descending volleys; MCS; TMS; UWS