Editorial Commentary by Robert M. Bernstein, M.D., New York, NY
Dermatol Surg 2000; 26(1): 31.
In 1984, Dr. Richard Shiell conceived of the term “X-factor” to describe the unexpected poor growth in a small percentage of patients undergoing a hair transplant. Drs. Norwood and Shiell hypothesized that this X-factor might be due to an immunologically mediated rejection producing a localized ischemia to the grafts. The original concept of an X-factor was for it to be a diagnosis of exclusion after “all other known causes of poor growth” in the hair transplant process had been eliminated. However, the quest to elucidate all of these “known” causes has proven to be a formidable challenge.
A major obstacle to sorting out the various causes of poor growth is that the hair transplant procedure itself is constantly changing. The problems that affected the large grafts of the early 1980’s, which produced phenomena such as “doughnutting,” no longer apply to the small graft hair transplants in vogue today. However, megassessions, with their long operating time, reliance on a large surgical team and use of more delicate grafts, introduce a new set of problems, all potentially manifesting as poor growth.
Significant progress has been made in recent years with regard to reducing the number of elements that might be lumped in the X-factor category. Greco, in 1994, greatly increased our awareness of the problems in dealing with small grafts with his introduction of the term “H-factor” to describe iatrogenic contributions to poor growth and his focus on mechanical trauma as a major culprit in the hair restoration. He offered the logical explanation that as grafts became smaller (and the surface area to volume ratio larger) they would be more subject to a host of insults that included crushing, squeezing, bending, drying, and warming.
To help understand poor growth during hair transplant, Dr. Limmer examined the time grafts were kept outside the body, Drs. Cooley and Vogel implicated trauma to the dermal papillae, and Dr. Kim experimented with follicular transection. Dr. Seager and the other follicular unit enthusiasts (me included) felt that even the act of separating intact hair follicles from their naturally occurring groups might impair growth.
The X-factor, a general term for the unknown that elicits a visceral discomfort in physicians and scientists alike, was being attacked from all sides, but the more numerous the hypothesis, the more difficult it became to design studies to isolate each issue, and the more difficult it was to ascertain which of the ideas were clinically important.
Dr. Gandelman appears to have taken a giant stride in solving the problem. Although his light and electron microscopic analysis of injured grafts will only temporarily circumvent the need for the bilateral controlled human studies that will ultimately be necessary to confirm his basic science research, the implications of his work are enormous.
It appears that Dr. Gandelman has identified a common denominator for many different forms of graft injury during the hair restoration process. Not only does desiccation disrupt cell membranes and destroy intra-cellular structures, but poorly hydrated grafts are more subject to the many mechanical and thermal stresses that we endlessly obsess about, namely: crushing, squeezing, bending, and warming.
This study does not address the issue of whether intact follicular units may have a greater susceptibility to the effects of dehydration than larger grafts, or more resistance than very thin 1- and 2-hair micrografts, but then it doesn’t really matter. It should be a relatively simple task to keep all of our grafts well hydrated during the hair transplant to prevent this important form of injury. Then, while our grafts are soaking safely, we will have time to decide which of the less important factors to fret about next.