The aim of this study was to translate the NCS from English into Chinese and determine the validity of this Chinese version.

The assessment and early diagnosis of pain is of great importance for pain management and treatment in patients with disorders of consciousness. The Nociception Coma Scale (- Revised) is only applicable to assess pain of DOC patients in international clinical setting. The aim of this study was to translate the NCS from English into Chinese and determine the validity of this Chinese version. To test internal reliability and inter-rater reliability, both rater A and rater B assess the perception of pain on day 1; and to obtain test-retest reliability, rater A assessed all patients repeatedly on day 2. 'Faces, Legs, Activity, Cry, Consolability' (FLACC) was used to analysis concurrent validity by rater A.

Inclusion Criteria:

• age ≥ 18 years old;
• no administration of neuromuscular blockers or sedation within the 24 hours of enrolment;
• the presence of periods of eye opening (indicating wakefulness and rest cycles);
• a diagnosis of VS or MCS, based on more than 4 times behavioral assessment performed using the Coma Recovery Scale-Revised within 2 weeks.

Exclusion Criteria:

• Coma;
• documented history of prior brain injury;
• psychiatric or neurologic illness;
• neuromuscular blocking agents or sedative drugs administered within the prior 24 hours;
• no documented history of a prior coma, critical illness or unstable medical condition;
• upper limb contusions, fractures (based on the imaging examination) or flaccid paralysis (by using noxious stimuli to upper limbs, motor sub-scale scores <1).