The Vasodilator Effect of a Cream Containing 10% Menthol and 15% Methyl Salicylate on Random-Pattern Skin Flaps in Rats

Abstract

Background: It is still difficult to prevent partial or full-thickness flap necrosis. In this study, the effects of a cream containing menthol and methyl salicylate on the viability of randompattern skin flaps were studied.

Methods: Forty female Sprague-Dawley rats were divided into two equal groups. Caudally based dorsal random-pattern skin flaps were elevated, including the panniculus carnosus. In the study group, 1.5 mL of a cream containing menthol and methyl salicylate was applied to the skin of the flap, and saline solution (0.9%) was used in the control group. Upon completion of the experiment, flap necrosis was analyzed with imaging software and radionuclide scintigraphy. Histopathological measurements were made of the percentage of viable flaps, the number of vessels, and the width of the panniculus carnosus muscle.

Results: According to the photographic analysis, the mean viable flap surface area in the study group was larger than that in the control group (P=0.004). According to the scintigrams, no change in radioactivity uptake was seen in the study group (P>0.05). However, a significant decrease was observed in the control group (P=0.006). No statistically significant differences were observed between the groups in terms of the percentage of viable flaps, the number of vessels, or the width of the panniculus carnosus muscle (P>0.05).

Conclusions: Based on these results, it is certain that the cream did not reduce the viability of the flaps. Due to its vasodilatory effect, it can be used as a component of the dressing in reconstructive operations where skin perfusion is compromised.

Keywords: Menthol; Methyl salicylate; Perfusion; Surgical flaps; Vasodilator agents.

Fig. 1. A modified McFarlane flap

(A) Elevation of a caudally based dorsal skin flap, (B) skin closure and application of 1.5 mL of cream on a rat in the study group.

Fig. 2. Measurement of the necrotic area of the flap surface

The dashed line represents the measured surface area.

Fig. 3. Measurements of the regions of interest (ROIs)

Measurements of the ROIs on flaps in the (A, B) study and (C, D) control groups. The flaps were divided into three ROIs, referred to as ROI A, ROI B, and ROI C. Scintigrams (A, C) before and (B, D) after the experiment. The white arrow shows the radionuclide-soaked material that was used to identify the end of the flap.

Fig. 4. Measurement of the manually marked count of the viable flap area

The measurement of the manually marked count of the viable flap area is shown by an asymmetric line that encloses the hyperemic area of the flap. The rectangle represents the entire flap area. A scintigram was taken (A) before and (B) after the experiment.

Fig. 5. Combination of a scintigram and a photograph

An image obtained after digitally combining the photographs and the scintigrams. In the study group, (A) scintigrams taken before the experiment showed little perfusion in the flap, while (B) scintigrams taken after the experiment showed almost no perfusion in the flap.

Fig. 6. Combination of a scintigram and a photograph

In the control group, (A) half of the flap was perfused before the experiment, and (B) perfusion was only found in the pedicle region after the experiment.

Fig. 7. Histopathology

(A) Measurement of capillary vessel density (H&E, ×400). (B) Measurement of the thickness of the panniculus carnosus muscle (PCM) at three different points in the necrotic region. An asterisk shows the dermal layer, the plus sign indicates the PCM, black arrows show the vessels, and double arrows indicate the thickness of the PCM (H&E, ×40).

Fig. 8. Mean flap surface areas