Treating Hyperhidrosis
While working with wounded warriors in the dermatology, prosthetics, and wound care clinics at WRNMMC, it repeatedly became clear that our current treatment options for hyperhidrosis in this population were not routinely tolerated or efficacious. Although hyperhidrosis of the axillary or palmoplantar region is a commonly encountered problem with clear treatment algorithms and management strategies, hyperhidrosis in the setting of a residual limb following amputation is somewhat unique and without definitive permanent cure. In approaching this problem, our institution has implemented a variety of therapies to the residual limb that have been well described and effective in the treatment in the axillary region.
Topical antiperspirants (ie, aluminum chloride) are well-documented treatments of hyperhidrosis and work by the formation of a metal iron precipitate when binding with mucopolysaccharides. These complexes cause damage to epithelial cells lining the ostia of eccrine glands, forming a plug in the lumen of the eccrine duct.6 Unfortunately, irritant contact dermatitis has affected the majority of our residual limb patients who have used topical antiperspirants and has led to poor compliance. Glycopyrrolate, an antimuscarinic agent, often is used with varying degrees of success. It works as a competitive antagonist blocking the acetylcholine muscarinic receptors that are responsible for the innervation of eccrine sweat glands. Several of our residual limb patients have a history of global hyperhidrosis and have responded favorably to 1- to 2-mg doses of glycopyrrolate administered twice daily. The side-effect profile headlined by xerostomia, urinary retention, and constipation has, as it often does, limited the dosing. We have observed that with the use of glycopyrrolate, these patients admit to less overall sweating but experience only a mild decrease in the cutaneous problems they experience over the residual limbs, which is likely attributed to the prosthetic liner that induces hyperhidrosis by preventing sweat evaporation from the residual limb. Patients may not be sweating as much, but they are still sweating and that sweat is unable to evaporate from under the liner.
Botulinum toxin is a common treatment of axillary hyperhidrosis and its effects on residual limbs are the same.5,7 Botulinum toxin types A, B, and E specifically cleave soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes, which prevents neurosecretory vesicles from fusing with the interior surface of the plasma membrane of the nerve synapse, thereby blocking release of acetylcholine.8 In inhibiting acetylcholine release, the signal for eccrine secretion is blocked. This therapy has been effective in our residual limb patients who tolerate the treatment. It typically involves the injection of 300 to 500 U of botulinum toxin type A diluted with 0.9% saline at 2 to 5 U per 0.1 mL into the residual limb.5 As with the other treatments, there are side effects that complicate compliance. Most residual limb treatments require 150 injections, which can be uncomfortable for this patient cohort. The majority of these wounded warriors have abnormal anatomy because of the traumatic nature of their injuries (ie, improvised explosive device attacks, artillery injury), and they often experience hyperesthesia, phantom limb pain, and notable scarring. These injections can be extremely painful, which often limits their utility. In addition, the therapy only provides 3 to 6 months of symptom relief. Our compliance rate for returning patients has not been good and we suspect that it is likely due to the discomfort associated with the injections.
Other therapies such as laser hair removal and iontophoresis have been attempted but have not yielded great results or compliance. In addition to the limitations of these treatment methods, the residual limbs have presented their own unique set of challenges; complications have included varied anatomy of the residual limbs, scarring, sensitivities, and heterotopic ossification. Temporary remedies such as botulinum toxin injections also present logistical complications because they require repetitive procedural appointments that can be quite burdensome to attend when these patients move back home, often far away from our large military treatment facilities.
A New Therapy With Exciting Potential
With the recent advent of microwave thermal ablation technology, the potential for a different, possibly permanent treatment was discovered. Microwave thermal ablation of the eccrine coils has been proven safe and effective in the prolonged reduction of hyperhidrosis of the axillae and has presented as a potential therapy for our residual limb hyperhidrosis patient population. This technology produces heat that is targeted to a specific depth in the treated tissue while cooling the epidermis. There are various treatment levels that can be used to deliver graded intensities of heat. When the deep dermis is targeted, adnexal structures are denatured and destroyed, causing diminished or eliminated function. Eccrine sweat glands, apocrine glands, and even hair follicles are affected by the therapy. The manufacturer of the only microwave thermal ablation device on the market that is approved by the US Food and Drug Administration to treat axillary hyperhidrosis has suggested that these effects are long-term and possibly permanent.9 After several iterations with this technology, we have been able to successfully apply microwave thermal ablation of eccrine coils to 5 residual limbs and are excited about the promise that this technique possesses. A report of our index case will be published soon,10 and we are looking forward to launching our protocol treating traumatic lower extremity amputee patients that have hyperhidrosis with microwave therapy ablation technology here at WRNMMC.