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Post-stroke Shoulder Pain (PSSP) is a debilitating condition that occurs in 30-70% of stroke patients (1,2). It is associated with shoulder subluxation and it frequently contributes to loss of upper limb use and an inability to perform basic activities of daily living. PSSP is a multifactorial pain mechanism that involves central, peripheral as well as nociceptive and neuropathic components. The peripheral nervous system (PNS) is particularly impaired, since several peripheral nerves that innervate the glenohumeral (GH) joint (axillary, suprascapular, lateral pectoral) are involved in the peripheral transmission of pain to the central nervous system. Peripheral nerves also have descending motor components and are involved in the altered mechanics (upper arm weakness and spasticity) and the resulting malalignment of the GH joint. The axillary nerve, in particular, controls an important motor component via activation of muscles (teres minor and deltoid) that promote rotation and elevation of the GH joint. Peripheral nerve stimulation, specifically stimulation of the axillary nerve, is a promising treatment for PSSP (3).

Introduction

Seven PSSP patients from four different clincal sites were implanted with a StimRouter peripheral neuromodulation device (Bioness, Valencia, CA) consisting of a peripheral stimulation lead placed adjacent to the axillary nerve, and a lead receiver placed under the skin. The peripheral lead was guided, under ultrasound guidance (Figure 1), until an appropriate deltoid twitch response was elicited. The final lead position was verified under fluoroscopy as the lead was buried anteriorly in an L-shape (Figure 2), across the lower deltoid muscle. The flexible lead receiver was placed under the skin surface of the posterior/middle deltoid muscle. An external pulse transmitter was used to run the stimulation program.

Methods

Patients from four different sites are included in this study. Visual analog scale (VAS) was used to assess pain. VAS scores were recorded prior to implantation and at various times after the start of stimulation (Table 1, 2, 3).

Results

Conclusion Peripheral nerve stimulation targeting the axillary nerve is a promising treatment for PSSP, that may improve quality of life in stroke patients. The stimulation probe can be implanted in under 15 minutes with ultrasound or fluoroscopy guidance. Peripheral excitation of sensory and motor nerves may have an effect on the central nervous system, leading to increased blood flow to the injured area and reduced spasticity. Implantable peripheral neurostimulation therapies can provide a safe, effective pain management option that can improve the rehabilitation process in patients recovering from stroke (4).

REFERENCES

1. Harrison RA, Field TS. Post stroke pain: identification, assessment, and therapy. Cerebrovasc Dis. 2015;39(3-4):190-201.

2. Vasudevan JM, Browne BJ. Hemiplegic shoulder pain: an approach to diagnosis and management. Phys Med Rehabil Clin N Am. 2014 May;25(2):411-37.

3. Yu DT, Chae J, Walker ME, et al. Intramuscular neuromuscular electric stimulation for poststroke shoulder pain: a multicenter randomized clinical trial. Arch Phys Med Rehabil. 2004 May;85(5):695-704.

4. Deer T, Pope J, Benyamin R, et al. Prospective, Multicenter, Randomized, Double-Blinded, Partial Crossover Study to Assess the Safety and Efficacy of the Novel Neuromodulation System in the Treatment of Patients With Chronic Pain of Peripheral Nerve Origin. Neuromodulation. 2016 Jan;19(1):91-100.

Table 3

Table 2

Table 1

Figure 1 Figure 2

Axillary Nerve Posterior Humeral Circumflex Artery

Axillary Lead in situ

A Novel Implantable Peripheral Nerve Stimulator for

Post-Stroke Shoulder Pain (PSSP) W. Porter McRoberts, M.D.1, Michael Sein, M.D.2, Charles Kim, M.D.3, Scott Naftulin, D.O.4, Catalina Apostol, M.D.1, Haleem Abdul M.B.B.S.1,

1Holy Cross Hospital, FL; 2Weill Cornell Medical Center, NY; 3NYU Langone Medical Center, NY; 4DeSales University, PA.

ClinicalSites Patients

VAS Before Procedure

VAS After Start of Stimulation

Time Lapse After Start of Stimulation

1-A 10 61-B 6 12-C 10 3 5 Months 2-D 8 0 4 Years 3-E 10 33-F 9 2

4 4-F 7 3 2 Months

Results After Peripheral Stimulation in Post-Stroke Shoulder Pain Syndrome

1 Month

1 Month

1

2

3

Change in VAS After peripheral Nerve Stimulation

Clinical Sites Patients

VAS Before Procedure

VAS After Stimulation

Time Lapse After Start of Stimulation

1 1-A 10 6

1 Month 1-B 6 1

2 2-C 10 3 5 Months

2-D 8 0 4 Years

3 3-E 10 3

1 Month 3-F 9 2

4 4-G 7 3 2 Months

0

2

4

6

8

10

1-A 1-B 2-C 2-D 3-E 3-F 4-G

VAS SCORE

Patients

Change in VAS after Axillary Nerve Stimulation in Patients with PSSP

VAS BeforeProcedure

VAS AfterStart ofStimulation

1-A

1-B

2-C

2-D

3-E 3-F

4-G

0

2

4

6

8

10VAS SCORE

TIME

Change in VAS after Axillary Nerve Stimulation in Patients with PSSP

1-A1-B2-C2-D3-E3-F4-G

Visual Analogue Scale (VAS) is a measurement assessment of pain intensity with 0 on one end, representing no pain, and 10 on the other, representing the worst possible pain.