The Influence of Surgical Stress on Human Scalp Hair Fiber Dimensions

Human scalp hair is an ideal medium for investigating the physiology and chemistry of an individual at the time of hair formation. Hair is taphonomically robust and, through its continuous growth, creates a chronological record of biochemical history. Changes to the physical characteristics of human scalp hair can therefore provide information on the presence and timing of antemortem acute physiological stress events. Scalp hair samples were collected from males undergoing abdominal surgery for a variety of medical conditions. Surgery is a known and potent activator of the systemic stress response and the acute phase response, both of which require protein and lipid substrates for survival and wound healing. Hair samples were long enough to cover up to one month prior to surgery and one month following surgery. Methods for the assessment of hair fiber growth were compared for utility in stress analysis. Dimensions such as total fiber diameter, cuticle thickness, and cortex diameter were compared prior to and following surgery. This study was approved by all appropriate Ethics Review Boards. Results of method comparison suggest that increased magnification from standard 400x to 1000x does not provide significantly different data. Measuring hair diameter digitally also does not provide data which differ significantly from diameter measured manually. Variables constructed from combined measurements do provide data more appropriate for detecting stress-related changes in the hair fiber than single dimension variables. Fiber dimensions analysed showed statistically significant differences between pre- and post-operative values, which returned to normal in the fourth post-operative week.