Brain Injury Nociception Assessment Measure

Severe brain injury often results in a period of impaired consciousness and/or communication, which interferes with the patient’s ability to accurately report on symptoms. The gold standard for assessing pain and the adequacy of pain management is through self-report, which is not feasible for such patients.

Conditions that might cause pain (e.g., fractures, nerve damage) are common among patients who sustain their brain injuries through trauma. Regardless of the etiology of the brain injury, many patients are at risk for other painful conditions due to their illness, or as a result of surgical and other procedures used to treat the illness. Importantly, noxious conditions produce behavioral and physiologic responses even in unconscious patients (“nociception”), whereas consciousness is required for the subjective experience of “pain.” Thus, measures intended to focus on physical injury regardless of state of consciousness should avoid items that require conscious perception.

Observational measures of pain exist for other non-communicative populations, such as neonates and those with advanced dementia, but some of the items or the rating context are not appropriate for a brain injury sample. One measure – the Nociception Coma Scale – Revised (NCS-R) – was developed specifically for a brain injury population with disorders of consciousness. However, some of the items on the NCS-R cannot be endorsed for unconscious patients, such that the patient’s level of consciousness must be known to accurately interpret the score.

In contrast, the goal of this project was to develop an observational measure of nociception for use in the early post-injury period, when the patient’s level of consciousness may be changing but identifying and managing noxious conditions is a priority, regardless of the patient’s subjective experience. Thus, we sought to develop a measure that demonstrates a graded response to increasing intensity of noxious stimulation, and that performs similarly in conscious and unconscious patients and those who are agitated as well as those who are not.

The Brain Injury Nociception Assessment Measure (BINAM) was developed by collaborators at MossRehab and the University Hospital, Copenhagen. Some of the 15 candidate BINAM items were drawn from observational measures of pain designed for other populations, while others were based on pilot research conducted in Copenhagen. Items that appeared to require conscious processing for endorsement were avoided. Participants were assessed on multiple occasions during activities expected to be more and less comfortable and when receiving and not receiving analgesic medication. Rasch analysis was used to assess item fit and dimensionality, resulting in the deletion of 5 items and the re-coding of some of the remaining items.

The resulting 10-item BINAM can be reliably completed based on about 8 minutes of observation, and it is robust to missing data on certain items during administration. The BINAM score derived from such observations was lower in the presence of analgesia and higher during the activities expected to be more uncomfortable. BINAM scores show little relationship to level of consciousness or agitation, suggesting that the BINAM is specific to nociception.Current Status: In 2020, we published a peer-reviewed article on the development of the BINAM in The Clinical Journal of Pain. The 10-item BINAM demonstrated strong measurement properties in the initial validation study and also appears to track the number and complexity of certain known injuries. However, independent replication on a new sample is needed to verify the BINAM’s properties and to examine its use in the actual diagnosis and management of noxious conditions. Colleagues in Copenhagen, including Drs. Ingrid Poulsen and Rikke Guldager, are currently engaged in a follow-up study on the BINAM.