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Accepted Manuscript Bilateral brachial plexus injury after MiraDry® procedure for axillary hyperhidrosis: a case report Ross C. Puffer, MD, Allen T. Bishop, MD, Robert J. Spinner, MD, Alexander Y. Shin, MD PII:

S1878-8750(19)30191-3

DOI:

https://doi.org/10.1016/j.wneu.2019.01.093

Reference:

WNEU 11266

To appear in:

World Neurosurgery

Received Date: 19 December 2018 Revised Date:

7 January 2019

Accepted Date: 9 January 2019

Please cite this article as: Puffer RC, Bishop AT, Spinner RJ, Shin AY, Bilateral brachial plexus injury after MiraDry® procedure for axillary hyperhidrosis: a case report, World Neurosurgery (2019), doi: https://doi.org/10.1016/j.wneu.2019.01.093. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT Bilateral brachial plexus injury after MiraDry® procedure for axillary hyperhidrosis: a case report

Ross C. Puffer MD1 Allen T. Bishop MD2 Robert J. Spinner MD1

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Alexander Y. Shin MD2

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Running title: Bilateral BPI after MiraDry® Procedure

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Department of Neurosurgery

Department of Orthopedic Surgery

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From: Department of Orthopedic Surgery, Mayo Clinic, Rochester MN

Financial Disclosures: None of the authors has a financial interest in any of the products, devices, or drugs mentioned in this manuscript.

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Key words: bilateral brachia plexus injury;MiraDry®;axillary hyperhidrosis

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Corresponding Author: Alexander Y. Shin, MD Mayo Clinic, 200 First St. SW Rochester, MN 55905 Ph: 507-284-3689 Fax: 507-266-2533 [email protected]

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Abstract Multiple treatments are available for primary axillary hyperhidrosis, including non-invasive, microwave based thermal treatments designed to destroy sweat glands in the axilla. Often these

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procedures involve local anesthetic injection to the axilla, followed by placement of the

microwave emitter onto the skin and applying the heat treatment to varying depths of the subcutaneous tissues.

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Case Report

A 49-year old, thin and active woman (BMI 19.6) underwent microwave based treatment to the

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bilateral axillary regions. She experienced an electric sensation into the ulnar digits of the right hand during anesthetic injection, and then underwent the microwave thermal treatment. She suffered a bilateral brachial plexus injury with imaging evidence of severe, subcutaneous edema surrounding the nerves of the plexus in the axilla, as well as denervation atrophy of the arm and

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forearm muscles bilaterally. At the time of evaluation and EMG, 8 months after treatment, she had recovered significant strength in the left upper extremity, but continued to have evidence of a severe radial nerve injury on the right. EMG demonstrated some recovery and observation was

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recommended followed by secondary reconstruction if required. It is likely that the patient sustained thermal injury to the nerves in the axilla bilaterally, given the close proximity to the

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skin surface in a patient with a low BMI. Conclusion

In thin patients undergoing treatment of primary axillary hyperhidrosis, consideration should be given to the distal brachial plexus which may be at risk of damage with high powered microwave-based therapy.

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Introduction Primary axillary hyperhidrosis is a common condition, with a prevalence approaching

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1.4%. 7 Multiple treatments are available, but many are not considered a long-term solution outside of invasive surgical procedures. Non-invasive, microwave-based treatments have been developed and have shown efficacy in treatment of this condition. 2,4

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MiraDry® (Sientra, Santa Clara, CA) is a Food and Drug Administration approved device that uses microwave technology to heat the sweat glands in the dermal/hypodermal

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junction to a point of irreversible injury, resulting in treatment of hyperhidrosis. The patient is placed in a supine position with arms abducted over the head, exposing the axilla bilaterally. A grid with targets for local anesthetic is applied to the skin of the axilla, and 31 separate injections of local anesthetic (1% lidocaine with 1:100,000 epinephrine) are applied to each axilla. Next,

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the microwave emitter is positioned over the grid, and heat treatment is applied. There are five settings that adjust the degree of microwave power applied, but the authors could not readily find any information guiding which power settings to use in specific patient scenarios. The maximum

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depth of field on the highest setting has not been reported. The device received initial FDA clearance in 2011 and underwent a Class II medical device recall in April 2011 (recall number z-

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2591-2011) after reports of skin burns in patients treated with the MiraDry® system. The recall occurred in Japan and was completed after 8 devices underwent “field correction.” Several studies evaluating the MiraDry® system have demonstrated efficacy for

treatment of hyperhidrosis with minimal, local skin side effects in the area of treatment including edema, erythema, hair loss, skin markings and discomfort. 3,5No long-term complications were

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reported. 3,5 We present a case of bilateral brachial plexus injury after microwave-based treatment of primary axillary hyperhidrosis. Case Report

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A 49-year-old, bilateral hand dominant, thin and active female (BMI 19.6) was offered a percutaneous microwave treatment designed to treat primary axillary hyperhidrosis in the

waiting room of her dermatologist. During local anesthetic injection of (1% lidocaine with

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1:100,000 epinephrine), she noted an electrical shock sensation traveling to the ulnar digits of the right hand. She notified the provider and was informed that this was normal. The procedure

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continued and the microwave treatment was completed bilaterally at the highest energy level (5/5). Immediately after the completion of the procedure, the patient experienced profound weakness and numbness in bilateral upper extremities. She was informed that this would resolve. The following morning she noted severe right triceps weakness which resulted in a laceration on

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her face after reaching for a mug from a top cupboard. There was also loss of wrist and finger extension of the right hand, and diffuse median/ulnar nerve distribution weakness of the left hand.

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After three months of outpatient evaluation and no improvement, she underwent bilateral brachial plexus (Figure 1) and upper extremity MRI which demonstrated substantial

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subcutaneous and perineural edema in the axilla bilaterally as well as atrophy and signal changes within the distal musculature (Figure 2). She was referred for physical therapy and began to notice improvement in the left hand approximately 7 months after her MiraDry® procedure. At 8 months she underwent evaluation at our institution with EMG demonstrating a chronic, inactive left brachial plexopathy involving proximal radial, ulnar and median nerves in the region of the axilla, as well as a chronic right posterior cord plexopathy, with reinnervation features present in

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all examined muscles. Clinically, the patient had recovered modified British Medical Research Council (BMRC) grade 4 strength in median and ulnar innervated muscles of the left hand, but had persistent BMRC grade 0 strength in the wrist and finger extensors on the right. Given the

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findings of reinnervation on EMG, further observation was recommended with consideration of secondary reconstruction of the right radial nerve deficit via tendon transfers if no further recovery occurred.

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Discussion

This case highlights the propensity for brachial plexus injury in patients undergoing procedures

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targeting the axillary region. It is unclear whether any of the 31 injections of local anesthetic in each axilla caused the brachial plexus injury or if unintended field effects of the microwave emitter led to nerve irritation and damage. The persistence of the deficit, as well as the depth of edema evident on MRI may suggest that the microwave heating played a more significant role in

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the nerve damage than the local anesthetic. All local anesthetics can be neurotoxic at highenough levels, however lidocaine has a lower toxicity than the local anesthetic bupivacaine. 6 The patient described an electric shock sensation into the right hand during injection of the local

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anesthetic, which may suggest an injury was sustained during needle insertion, however the patient also experienced a deficit of the left hand, and did not report any shooting pains into the

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hand during left-sided injection, suggesting a microwave heat damage etiology. It is also plausible that the combination of local anesthetic and tissue heating lead to an increased degree of nerve injury. There has been significant recovery over time, suggesting a possible neurapraxic-type injury on the left side, but the presence of fibrillation potentials in the extensor musculature of the right forearm suggest a more substantial nerve injury, such as an axonotometic lesion occurred.

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A literature search was performed, and several cases of brachial plexus injury after microwave-based treatment were found. Three separate patients developed a deficit after the procedure, and all three had persistent deficits at 6 months, with evidence of incomplete, but

power setting.

1,3,8

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ongoing recovery. In one of the reports, the injury occurred even with the device on the lowest Complication rates in the currently published series suggest no long term side

effects reported in any of the original 31 patients at 2 years of follow-up. 3,5 Given the proximity

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of the distal brachial plexus to the skin edge within the axilla, especially in thin, active patients, hydrodissection after local anesthetic administration to buffer the brachial plexus, or decreased

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depth of heat treatment should be considered. Conclusion

In thin patients undergoing treatment of primary axillary hyperhidrosis, consideration should be given to the distal brachial plexus which may be at risk of damage with high powered

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microwave-based therapy.

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Informed consent was obtained for experimentation with human subjects.

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Glaser DA, Coleman WP, 3rd, Fan LK, Kaminer MS, Kilmer SL, Nossa R, et al: A

randomized, blinded clinical evaluation of a novel microwave device for treating axillary

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hyperhidrosis: the dermatologic reduction in underarm perspiration study. Dermatol Surg. 2012;38:185-191. https://doi.org/10.1111/j.1524-4725.2011.02250.x Hong HC, Lupin M, O'Shaughnessy KF: Clinical evaluation of a microwave device for

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Johnson JE, O'Shaughnessy KF, Kim S: Microwave thermolysis of sweat glands. Lasers

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Surg Med. 2012;44:20-25. https://doi.org/10.1002/lsm.21142 Lupin M, Hong HC, O'Shaughnessy KF: Long-term efficacy and quality of life assessment for treatment of axillary hyperhidrosis with a microwave device. Dermatol

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Strutton DR, Kowalski JW, Glaser DA, Stang PE: US prevalence of hyperhidrosis and impact on individuals with axillary hyperhidrosis: results from a national survey. J Am Acad Dermatol. 2004;51:241-248. https://doi.org/10.1016/j.jaad.2003.12.040

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Suh DH, Lee SJ, Kim K, Ryu JH: Transient median and ulnar neuropathy associated with a microwave device for treating axillary hyperhidrosis. Dermatol Surg. 2014;40:482-

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485. DOI: 10.1111/dsu.12425

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Legends: Figure 1: Coronal T2-weighted MRI demonstrating extensive subcutaneous and soft tissue edema in both axillae extending proximally within the subpectoral

the distal brachial plexus and the terminal branches bilaterally.

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regions along the distal brachial plexus bilaterally (arrows). This edema and fluid signal encases

Figure 2: (A) Axial T2-weighted MRI of the right arm demonstrates denervation atrophy of the

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triceps (asterisk). (B) Radial-innervated muscle atrophy (asterisk) is present in the distal forearm on T2-weighted MRI on the right. (C) Muscle atrophy (asterisks) is present in both the flexor and

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extensor compartments of the distal left forearm, suggesting radial, median and ulnar nerve

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injury.

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ACCEPTED MANUSCRIPT BMI – Body mass index BMRC - British Medical Research Council EMG – Electromyogram FDA – Food and Drug Administration

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MRI – Magnetic resonance imaging