Primitive reflexes associated with delirium: a prospective trial

The presence of primitive reflexes (PRs) may have diagnostic or prognostic value in the evaluation of cognitive impairment.

We hypothesized that the presence of preoperative PRs would predict the development of postoperative delirium and that the emergence of PRs postoperatively would be positively associated with the emergence of delirium.

Patients participating in a larger study on the prophylaxis of postoperative delirium were evaluated for the presence of six PRs (grasp reflex [left and right], palmomental reflex [left and right], glabellar tap, and snout reflex), preoperatively and postoperatively. The presence of PRs was then correlated with the development of delirium.

Of the 79 patients studied, 29% (n = 23) developed delirium during the postoperative period. The preoperative presence of one PR did not predict the development of delirium, but the only patient with >1 PR preoperatively went on to develop delirium in the postoperative period. Similarly, having one frontal release sign in the postoperative period did not correlate with delirium, while the appearance of more than one PR was associated with a greater likelihood of delirium. Of the 11 patients who had two or more frontal release signs during one postoperative examination, six (55%) developed delirium. Of the five patients who showed three or more frontal release signs, 4 (80%) developed delirium.

Our study is the first to investigate the relationship between the appearance of PRs and the development of delirium. We have provided some evidence that PRs are associated with acute CNS dysfunction.