TAO is a rare, nonatherosclerotic segmental inflammatory vasculitis that commonly involves small- and medium-sized vessels and nerves of the extremities. TAO is associated with a high risk of limb amputation. As reported in a study by Cooper et al8 utilizing a follow-up survey and chart review of 111 patients with TAO, 25% of patients experience their first amputation at 5 years after diagnosis, 38% at 10 years, and 46% at 20 years. Reviews1,9,10 reported several risk factors, such as tobacco and marijuana use and chronic anaerobic periodontal infection. Pathological characteristics show TAO is a highly cellular, inflammatory intraluminal thrombus with relative sparing of the internal elastic lamina.11 Nonetheless, its pathogenesis remains unclear. It has been postulated that smoking may induce a delayed type of hypersensitivity or toxic angiitis, increasing production of cytokines and contributing to the inflammatory response.12,13 In addition, endothelial dysfunction with impairment of endothelium-dependent vasodilation and mutation of the prothrombin gene also may be involved.14,15 Cessation of tobacco use is the only known effective method of halting the progression of TAO; according to a review by Olin,1 94% of persons who quit smoking avoided amputation, whereas 43% of those who continued smoking required 1 or more amputations. Unfortunately, according to retrospective analysis by Ohta et al16 of 110 patients with TAO, less than half of patients were able to quit smoking.
Medications such as iloprost, bosentan, phosphodiesterase type-5 inhibitors, and calcium channel blockers have been used to treat TAO. Surgical modalities include thrombolytic therapy, arterial reconstruction, lumbar sympathectomy, spinal cord stimulation, microvascular flap transfer, pedicled omental graft, distraction osteogenesis, and, when required, amputation.17-21 However, the treatment of TAO is still being studied. Based on the results of a variety of studies4-7,22 of FIR therapy applied to arteriovenous fistulas and wound healing, the current authors applied FIR therapy to treat this patient.
The meta-analysis by Bashar et al4 that included 4 randomized, controlled trials showed FIR therapy may positively influence the patency rate of arteriovenous fistulas. Unassisted patency, assessed in 610 patients, was significantly better among those who received FIR therapy (228/311) compared to controls (185/299) (pooled risk ratio of 1.23 [1.12-1.35], P = .00001). Based on Lin et al’s5 randomized controlled study (N = 122), patients were randomly allocated to the intervention (n = 60) and control (n = 62) groups. FIR therapy improved the access flow and facilitated a higher rate of maturation along with patency of newly created arteriovenous fistulas in patients with stage 4 and stage 5 chronic kidney disease in comparison to controls. Animal studies by Huang6 revealed FIR therapy promotes collateral flow recovery and new vessel formation in diabetic mice. In a clinical study by Li et al7 and an animal study by Toyokawa et al,22 FIR therapy enhanced microcirculation flow and significantly decreased limb circumference in extremities with lymphedema and promoted wound healing in a rat model in comparison to controls.
Based on the meta-analysis and systematic review of FIR therapy in dialysis, arteriovenous fistula maturation and survival by Bashar et al4; Doppler perfusion imaging and immunofluorescence staining study in diabetic mice by Huang et al6; a randomized, controlled trial of FIR therapy on arteriovenous fistula by Lin et al,5 in comparison to control, the thermal effects of FIR increased the skin temperature up to only 38˚ C to 39˚ C after treatment for <60 minutes at a distance of 20 cm above the skin, inducing vasodilation and increasing blood flow without burning the skin. The nonthermal effects of FIR therapy improve endothelial dysfunction, augment angiogenesis, decrease oxidative stress, inhibit platelet aggregation, and suppress inflammation by enhancing the activity of endothelial nitric oxide synthase, thereby improving endothelial progenitor cell function and stimulation of heme oygenase (HO-1) expression. According to the etiology of TAO and mechanisms of FIR therapy, it is reasonable to consider the use of FIR therapy in TAO.
In this study case, the wound began to heal and Mr. U’s pain decreased when FIR therapy and tapered smoking were combined over 8 months. The wound healed completely and Mr. U experienced no pain 2 months after he stopped smoking. With the implementation of FIR therapy, the affected leg showed evidence of vasodilation and enhanced blood flow along with an improved ankle/brachial index. Although it is uncertain whether smoking cessation alone would have affected healing, this case represents a successful clinical outcome when TAO was used as a adjuvant treatment along with cessation of smoking.