The Return of Sensitivity to Cold, Warmth and Pain from Excessive Heat in Free Microvascular Flaps

Abstract

Recovery of sensitivity to cold, warmth and pain caused by excessive heat in various types of free microvascular flaps was studied psychophysically in 27 patients who had undergone such operations four months to four years earlier. A thermal stimulator based on the Peltier principle and controlled by a microprocessor was used to measure the sensitivity to temperature in the transplants. The results were compared with the measured thresholds in the opposite sites in corresponding normal body areas. The present study showed that sensitivity to cold, warmth, and pain caused by excessive heat did return to some free microvascular flaps. According to the measurements the sensation started to return after 6 months in some flaps, and all types of thermal stimuli were felt by one patient as early as 10 months after operation. The return was more pronounced in younger people and in smaller flaps. If the hands, feet, or head defects were reconstructed with a thin skin flap (posterior aspect of thigh, dorsum of foot, or subscapular) the recovery of sensitivity was verified. Sensation returned to the musculocutaneous and osteomusculocutaneous transfers if they were on the hands or the head, or if they were sutured to healthy tissue with normal sensation. The main advantage of the psychophysical sensory testing method that we used is that it gave exact numerical data that made it possible to compare results among the different patient groups and even those obtained at different clinics and laboratories.

Some biological characteristics of transferred free flaps

“…In the first period, few scientific statements were publicized. [4][5][6]16 These statements were contradictory. They examined only some types of sensitivity or only muscular free flaps sensitivity.…”

“…[4][5][6] Pain sensitivity was evaluated using Bernard's diadynamic current of 100 MHz frequency and of 1-15 mA intensity (Figs. 5 and 6).…”

Patterns of sensory and autonomic reinnervation of long-standing myocutaneous microvascular flaps and split-skin grafts applied to fascial beds

“…The microvascular flaps studied were all non-neurotized and located on the lower limbs. The location of the recipient site of the flap has been reported to have an impact on the recovery of sensation (5,11). Improved sensory recovery in flaps to the hands, feet and head compared with those of the lower limb has previously been reported (5,11).…”

Facial and Hand Allotransplantation

“…Sensory nerve recovery for free tissue reconstruction is greater in the face than for that of the trunk or lower extremities in both neuroti- nized and non-neurotinized flaps, which shows the greater cortical representation the face receives in the human homunculus (Lahteenmaki et al 1991;Kuriakose, et al 2001;Kerawala et al 2006;Bianchi et al 2010). …”

“…Inclusion of skin within a free flap improves sensory recovery, whereas the presence of muscle and bone may act as a barrier for neurontinization from the recipient bed (Siemionow et al 2011). Patients with thinner transplants, less transplanted tissues, and younger patients may have better sensory recovery (Lahteenmaki et al 1991); however, more clinical data with facial transplantation needs to be accumulated before this will be known.…”