Delayed Growth Revisited
Robert M. Bernstein, MD, New York, NY and William R. Rassman, MD, Los Angeles, CA
Hair Transplant Forum Int’l. 1997; 7 (6): 14.
Letters to the editor
When any hair transplant surgery is performed, the grafts are removed from their original blood source so that they must survive, for a time, outside the body. The “shock” caused by this interruption of blood supply is probably the major cause of the post hair transplant effluvium (shedding) of the newly transplanted grafts and probably also contributes to delayed growth after the hair transplant – when it occurs. This insult is further exacerbated by the time it takes for the microvasculature to reconnect and nourish the grafts in the days following the surgical hair restoration.
It has been postulated that “the most important causative factor for delayed growth [is] insufficient blood supply.” This assumption, however, has not been proven. It has also been stated that “If hair transplantation is done in a technically competent manner, and blood supply adequate, hair will grow in a timely manner. If, on the other hand, the available blood supply is overwhelmed by huge numbers of grafts, delayed or no growth is to be expected.”
The problem with this statement is that it is too vague. Will a hundred of the standard 3-mm plugs placed in “a competent manner” have enough blood supply to insure maximum growth? And would one recognize delayed growth in a plug if it occurred? Will the placement of 2,500, 1-4 hair follicular units into 18-gauge needle sites, over an area of 200 square cm (which is 12.5% of the original density) outstrip the blood supply and, therefore, represent incompetence? Surgical hair restoration doctors routinely transplant densities of 25-30 grafts/cm2 in 1000 graft sessions. Is this reasonable to do?
We all know that blood supply is critical to graft survival. But the questions still unanswered are what parameters are needed in the hair transplant surgery to insure that this supply is adequate. Does the much smaller wounding provided by micrografting and follicular unit hair transplantation permit much greater numbers of grafts to be safely moved per session? And what is the limit? Although we all have our clinical opinions about this issue, the answer is still not clear. And neither are the actual contributions of variable growth cycles, severing dermal papillae, mechanical trauma, desiccation, or any of the other factors involved in the surgical hair restoration process that we had mentioned. Further research is needed in all of these areas.
We closed our hair transplant growth article with: “Our guess is that delayed growth has always been part of the process, representing a normal physiologic shift in the growth cycle on one hand, and a reaction to sub lethal injury on the other, with the very small grafts making both of these changes more obvious. What percentage each represents and how much of “delayed growth” will turn out to be no growth at all still needs to be determined. But before we panic about perceived no growth and before we set our patients up for unrealistic expectations about how soon their growth may occur, we should work to have a better understanding of all the biologic factors that impact our surgery.”