Table 3.
Common Signs and Characteristics Evaluated in Pain in DOC Patients.
| Signs/Symptoms/Characteristics | Description | Evaluation in MCS Patients | Evaluation in VS/UWS Patients |
|---|---|---|---|
| Motor Response | Assessed in the NCS and NCS-R as part of the behavioral response to pain stimuli. | Higher-level responses, such as flexion or withdrawal. | Lower-level responses, such as abnormal posturing or none/flaccid. |
| Verbal Response | Evaluated in the NCS and NCS-R; factors such as crying, groaning, or intelligible verbalization are considered. | Higher-level responses, such as vocalization or intelligible verbalization. | Lower-level responses, such as groaning or no response. Necessary to consider lower responses due to tracheostomy conditions. |
| Facial Expression | Assessed as part of NCS and NCS-R, includes evaluation of reactions like grimacing. | More expressive, such as a cry or grimace. | Startled/oral reflexive movements or no response. |
| Visual Expression | Assessed as part of NCS, includes evaluation of reactions like fixation. | Higher-level responses, such as fixation and eye movements. | Startled or no response. |
| Pain Localization | Higher-level behavior indicative of pain as assessed by the NCS and NCS-R. | Observable. | Not observable. |
| Personalized Stimulation Reaction | Involves reactions to personalized stimuli, such as opening the hand, abducting the upper limbs, and mobilizing the head. | More demonstrated. | Less demonstrated. |
| Cardiac Frequency (Heart Rate Variability) | HRV can be used to assess autonomic responses to pain, such as increased sympathetic activity and reduced vagal modulation. | More stable HRV. | Increased sympathetic activity and reduced vagal modulation. |
| Galvanic Skin Response (GSR) | GSR measurements can indicate physiological responses to pain stimuli. | Trace conditioning was observed in healthy controls. No studies are present for MCS patients. | Can show trace conditioning to noxious stimuli. |
| Tracheostomy Condition | Pain assessment should consider lower cut-off values for tracheostomized patients due to lower verbal subscale scores. | Not applicable. | Lower cut-off values for nociception. |
| Spasticity | Severe spasticity can affect pain assessment in DOC patients. | Possible. | Possible. |