Journal of Brachial Plexus and Peripheral Nerve Injury BioMed Central Case report Open Access Serratus muscle stimulation effectively treats notalgia paresthetica caused by long thoracic nerve dysfunction: a case series Charlie K Wang1, Alpana Gowda2, Meredith Barad1,2, Sean C Mackey1,2 and Ian R Carroll*1,2 Address: 1Department of Anesthesia, Stanford University School of Medicine, Stanford Systems Neuroscience and Pain Lab, Palo Alto, CA, USA and 2Department of Anesthesia, Division of Pain Management, Stanford University School of Medicine, Stanford Pain Management Clinic, Redwood City, CA, USA Email: Charlie K Wang - [email protected]; Alpana Gowda - [email protected]; Meredith Barad - [email protected]; Sean C Mackey - [email protected]; Ian R Carroll* - [email protected] * Corresponding author Published: 22 September 2009 Received: 7 August 2009 Accepted: 22 September 2009 Journal of Brachial Plexus and Peripheral Nerve Injury 2009, 4:17 doi:10.1186/1749-7221-4-17 This article is available from: http://www.jbppni.com/content/4/1/17 © 2009 Wang et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Currently, notalgia paresthetica (NP) is a poorly-understood condition diagnosed on the basis of pruritus, pain, or both, in the area medial to the scapula and lateral to the thoracic spine. It has been proposed that NP is caused by degenerative changes to the T2-T6 vertebrae, genetic disposition, or nerve entrapment of the posterior rami of spinal nerves arising at T2-T6. Despite considerable research, the etiology of NP remains unclear, and a multitude of different treatment modalities have correspondingly met with varying degrees of success. Here we demonstrate that NP can be caused by long thoracic nerve injury leading to serratus anterior dysfunction, and that electrical muscle stimulation (EMS) of the serratus anterior can successfully and conservatively treat NP. In four cases of NP with known injury to the long thoracic nerve we performed transcutaneous EMS to the serratus anterior in an area far lateral to the site of pain and pruritus, resulting in significant and rapid pain relief. These findings are the first to identify long thoracic nerve injury as a cause for notalgia paresthetica and electrical muscle stimulation of the serratus anterior as a possible treatment, and we discuss the implications of these findings on better diagnosing and treating notalgia paresthetica. Background at T2-T6 [3-6], degenerative changes to the corresponding Notalgia paresthetica (NP) is a poorly-understood condi- vertebrae [7], and possible involvement of a hereditary tion presenting with pruritus, pain, and paresthesias in an component [8]. Cutaneous innervation in this area is pro- area medial to the scapula and lateral to the thoracic vided by the medial cutaneous branches of the dorsal pri- spine. In addition, patients commonly report hyperpig- mary rami of the thoracic spinal nerves, which pass mentation of the skin and other skin abnormalities. It was through muscles stabilizing the scapula including the first described by Astwazaturow in 1934, but both etiol- rhomboid and trapezius (Figure 1). Immunohistochemi- ogy and prevalence of NP are unclear [1,2]. Previous cal investigations of the symptomatic area have been authors have postulated the causes of NP include nerve inconclusive [9-11]. NP has been treated to varying entrapment of the posterior rami of spinal nerves arising degrees of success with a multitude of palliative Page 1 of 6 (page number not for citation purposes) Journal of Brachial Plexus and Peripheral Nerve Injury 2009, 4:17 http://www.jbppni.com/content/4/1/17 TranscutaneousserratusulationventralEMSareaFigure directlyof unittopain2 anterior; the onand to lateral the theelectricalpruritus Leads lateral se borderrratus from sidemusc ofanterior aof the lehome the stimulation latissimus scapula,and electrical far lateraldorsi,indirectly themuscle providingaxillafrom to stim- the andthe Transcutaneous electrical muscle stimulation directly to the serratus anterior. Leads from a home electrical muscle stimulation unit on the lateral side of the scapula, in the axilla and ventral to the lateral border of the latissimus dorsi, providing EMS directly to the serratus ante- rior and far lateral from the area of pain and pruritus. MedialdrawnicadorsalFigure area ramiincutaneous 1of blue; presentation, of spinalCutaneous branches nerves with innerv ofdrawn medialdoationsrsal in cutaneousramiblue of Notalgiaof spinal branches Paresthet-nerves, of Medial cutaneous branches of dorsal rami of spinal nerves, drawn in blue; Cutaneous innervations of Notalgia Paresthetica area of presentation, with These findings are the first to identify long thoracic nerve medial cutaneous branches of dorsal rami of spinal injury with subsequent serratus anterior dysfunction as a nerves drawn in blue. Figure adapted from original in cause for NP and EMS of the serratus anterior as a possible Color Atlas of Anatomy by Rohen and Yokochi, 2006. successful conservative treatment. Case series presentation approaches directed specifically at the painful or pruritic All patients reported pain with or without pruritus skin, nerves, and muscle medial to the scapula, including between the thoracic spine and medial scapula which paravertebral nerve blocks [12], cervical epidural steroid grew progressively worse throughout the day. Further- injections [13], topical capsaicin [14,15], acupuncture more, all reported exacerbation with activities requiring [16], and botulinum toxin type A [17]. Systemic pharma- forward flexion of the arms such as driving, typing, wash- cology used in neuropathic pain more generally has also ing dishes, or putting objects on a shelf. Patients did not been directed at NP, including gabapentin [18] and oxcar- report skin abnormalities, and no hyperpigmentation was bazepine [19]. With the exception of a trial of topical cap- observed. When temperature sensation in the area of max- saicin reporting 30% relief of pruritus [15], no long-acting imal pain was tested with ice and compared to the contral- treatment has shown efficacy in a RCT, and a divergence ateral region, all patients reported reduced sensation of of explanations for the etiology remains. There is a need cold without frank numbness. All had injury to the long to better understand and more effectively treat NP. thoracic nerve or the cervical roots at C5-7 giving rise to the long thoracic nerve, despite the absence of clinically- The long thoracic nerve arises from branches of cervical apparent scapular winging. There was no evidence of nerve roots C5-C7 and innervates the serratus anterior hyperpigmentation or other dermatologic symptoms. muscle. Injury to the long thoracic nerve or its cervical Prior to treatment with EMS all patients had seen multiple roots leads to dysfunction of the serratus anterior, with physicians and physical therapists, and tried multiple consequent scapular winging or loss of normal scapular medications without relief. EMS of the serratus anterior protraction. We describe four cases of NP with known muscle was conducted at 70 Hz with a pulse width of 300 injury to the long thoracic nerve or the cervical roots giv- μs to induce tetany of the serratus anterior. Stimulation ing rise to the long thoracic nerve, where transcutaneous was prescribed to be 30 seconds on and 30 seconds off for electrical muscle stimulation (EMS) to the serratus ante- 15 minutes twice a day. All patients reported relief of pain rior in an area far lateral to the area of pain and pruritus beginning within days upon starting EMS, recurrence of (Figure 2) resulted in significant and rapid pain relief. pain if they discontinued stimulation for any prolonged Page 2 of 6 (page number not for citation purposes) Journal of Brachial Plexus and Peripheral Nerve Injury 2009, 4:17 http://www.jbppni.com/content/4/1/17 period, and maintenance of analgesic effects with only Case 3 intermittent stimulation necessary. A 40-year-old male physician presented with itching, par- esthesias, and when symptoms were severe, pain medial The patients described in this case series provided to the right scapula of 20 years duration, status post a tho- informed consent for the manuscript and/or accompany- racotomy performed while a child. The ipsilateral thora- ing images to be published. cotomy scar ran across the expected course of the long thoracic nerve. He reported no intercostal pain, and his Case 1 NP symptoms were located several inches medial to the A 39-year-old male presented with pain and pruritus posterior margin of the thoracotomy scar. Past treatments medial to the left scapula several months after sustaining included topiramate and over-the-counter analgesics. He an ipsilateral broken clavicle and multiple rib fractures in reported 70% relief of symptoms within the first two a bicycle accident. He reported a marked increase in pain weeks of using EMS to the serratus anterior muscle and with activity utilizing his arms. Unlike his other pain com- continues daily use as of September 2009. He continues to plaints which improved following the accident, over time use the stimulator intermittently after 9 months of follow- his left mid-scapular pain became more persistent and up. refractory. At 60 mg of duloxetine his medial scapular pain was replaced by a sense of itching, and then at 120 Case 4 mg disappeared completely, although he ultimately could A 34-year-old female presented with pain and pruritus not tolerate duloxetine due to "personality changes". Elec- medial to the right scapula, status post cervical fusions of trodiagnostic studies revealed cervical root dysfunction at C4-5 and C5-6 in 2006 due to degenerative joint disease. C5, C6, and C7 suspected to be a traction injury from She also presented with neural foraminal stenosis in C6- landing on his shoulder after going over the handlebars of 7. Electrodiagnostic studies were consistent with dysfunc- his bicycle.