"Mood rings": a new method of objective clinical assessment of peripheral nerve injuries

The clinical assessment of patients with peripheral nerve injury is primarily dependent on subjective clinical examination. We aimed to assess whether a thermotropic liquid crystal ring (TLC-ring) could provide the basis for an objective assessment of peripheral nerve injury by detecting temperature changes in the digits innervated by the damaged nerve. A group of patients with known median, ulnar or both digital nerve injuries were compared against a control group. TLC-rings, marketed to the general public as "mood rings", were applied to the affected and unaffected digits and the colour change recorded. Areas with nerve damage showed a statistically significant difference in colour response to those without damage. This study establishes the ability of TLCs to detect cutaneous temperature changes associated with peripheral nerve injuries. Further studies and improvements are needed to refine TLC as an acute assessment tool for peripheral nerve injuries.