Patients admitted to the intensive care unit with a cerebrovascular pathology and in a comatose state with a Glasgow score strictly less than 8, 24 hours after stopping sedation.

All patients included in the study will receive electroencephalograms (EEGs) of post-stimulation event-related desynchronisation (ERD)/event-related synchronisation (ERS) amplitudes of the median nerve on two occasions per week. These recordings will be made twice a day, once in the morning and once in the afternoon/evening, in order to take account of the patients' inherent nycthemeral rhythm.

A recording of 12 EEG electrodes from the scalp will be made during painless stimulation of the median nerve. The intensity of this stimulation will range from 3 to 14 mA, with a duration of 0.1 ms and a frequency of 5 Hz. This will result in a multiplication of the recording periods during and after stimulation. A final period of approximately 15 minutes of recording will be carried out with headphones on the patient, using simple, pre-recorded, standardized commands. These recordings will be continued for a period of three weeks following their inclusion.

The alterations in the electroencephalogram (EEG) signal in the event-related desynchronisation/event-related synchronisation cortical signature following median nerve stimulation will be analysed and correlated with the emergence of clinical motor intention.

The detection of cognitive-motor dissociation will rely on classification algorithms that detect the presence of motor activity in EEG signals following median nerve stimulation (MNS). The EEG signals recorded immediately after MNS will be represented as one or more covariance matrices, and several classifiers, including Riemannian classifiers, will then be trained on these matrices to classify a state of rest or motor activity in the EEG.

Progression of the Clinical Rating Scale-Revised (CRS-R) score:

Standardized clinical scale assessing level of consciousness across six subdomains: auditory, visual, motor, oromotor/verbal, communication, and arousal.

Total score: 0 to 23

Interpretation:

Lower scores indicate absence or very low levels of consciousness (coma or vegetative state/unresponsive wakefulness syndrome).

Intermediate scores indicate minimal but definite behavioral evidence of consciousness (minimally conscious state).

Higher scores indicate more complex behaviors consistent with a higher level of consciousness (emergence from the minimally conscious state).

Glasgow Coma Scale (GCS) Standardized clinical scale assessing level of consciousness based on three components: eye opening, verbal response, and motor response.

Total score: 3 to 15

Interpretation:

Lower scores indicate severe impairment of consciousness (coma or deep unconsciousness).

Intermediate scores indicate moderate impairment of consciousness. Higher scores indicate mild or no impairment of consciousness.

The functional neurological prognosis in the period subsequent to the event will be evaluated by the Glasgow Outcome Scale-Extended (GOS-E) Standardized clinical scale assessing functional outcome and disability following brain injury, based on overall level of independence and social functioning.

Total score: 1 to 8

Interpretation:

Lower scores indicate severe disability or death. Intermediate scores indicate moderate disability with some level of independence.

Higher scores indicate good recovery with return to independent functioning.