December 2018: Does post-traumatic cold intolerance last forever?
Norwegian investigators queried 71 patients who seven years previously had sustained avulsing/crushing/lacerating upper extremity injuries involving nerves. The investigators had previously queried these same patients three years after injury and were interested in knowing if this group had experienced changes over longer follow-up, information previously unavailable.
The researchers contacted the patients by mail and asked them to fill out the McCabe Cold Sensitivity Severity (CSS) questionnaire, which asks about five specific indoor activities such as holding a glass of ice water, washing hands in cold water, and holding a package of frozen food. In addition, participants scored a visual analog scale (VAS) that had five underlying descriptors ranging from “no discomfort” to “extreme discomfort” for the same activities that the CSS asked only “yes” or “no.”
RESULTS: Seven years after injury, 90% of the patients were still cold intolerant, and their three- and seven-year scores on the CSS were statistically equivalent. On the self-reported severity level, however, 28% had one or two-level reduction in cold hypersensitivity that occurred between three- and seven-year follow-up. Fourteen percent had an increase in symptoms of one level, and 58% had no change.
Using this same group of patients, the same investigators had previously reported a worsening in CSS scores for the first six months after injury, no change from six months to one year, and an improvement both from one to two years and from two to three years.
Although the current study indicates that CSS scores do not change between three and seven years, the patients had apparently adapted by wearing gloves and avoiding grasp of cold objects in the injured hand, which likely accounts for the improvement in the VAS scores in 28% of subjects.
COMMENT: Sadly, the answer to the opening question is “probably yes.” The good news you can tell patients, however, is that there is a fair chance that the severity of the cold intolerance will continue to diminish over at least seven years. Activity modification, more than neural adaptation, likely accounts for the improvement.