Suprascapular Nerve Pulsed Radiofrequency for Chronic Shoulder Pain in a Pediatric Patient

1. Introduction

 Shoulder pain  is  relatively common  in  the general pop- ulation and may result from an injury, inflammatory con- ditions, or a degenerative process. +e most common causes are related to  rotator cuff  disorders, glenohumeral and acromioclavicular capsulitis, or arthritis and joint instability [1, 2]. Most patients with chronic shoulder pain respond well to physical therapy, nonsteroidal anti-inflammatory drugs (NSAIDs), and activity modification. Injection  of a local anesthetic with  steroids is  also  effective to  alleviate in- flammation and to allow passive and active physical therapy [1,  3–5]. When  the pain  is  intractable, a trial  of pulsed radiofrequency (PRF)   of the suprascapular nerve may be indicated as a means to delay or avoid surgery [6–8].

Pulsed radiofrequency was developed as a modification of continuous radiofrequency. In the latter, a high-frequency alternating current is  applied to elevate the temperature

above 45–50°C to produce nonselective coagulative necrosis

of the nociceptive fibers. In PRF,  on the other hand, high- voltage short bursts of current (20 ms) are followed by silent phases (480 ms)  allowing  diffusion  of  heat, maintaining the temperature  in  the target tissue below 42°C  with the intention to produce prolonged “stunning” of nerve fibers without irreversible cell damage [8–11].

Pulsed radiofrequency (PRF)  of the suprascapular nerve has shown efficacy in  adults with chronic  shoulder pain [7, 8, 10–13], but there are no reports of its use in children. We present a case were an ultrasound (US)  guided PRF  of the suprascapular nerve successfully alleviated refractory chronic shoulder pain in a pediatric patient.

 2.Case Report

Informed consent was obtained from the patient and parents for the procedure and later for publication. A 53 kg, 14-year- old female, with a past medical history of septic arthritis of the left shoulder within the first month of life, presented with

a complaint of progressive pain since age 12. Her pain had been refractory to  analgesics including  opioids,  physical therapy, and intra-articular injection of local anesthetic and steroids for the past two years. +e patient was referred to the pain clinic after a trial of pregabalin and tramadol was unhelpful and 2 intra-articular injections of steroids and local  anesthetics failed to provide  analgesia. +e patient presented with severe pain  (numeric  rating scale ≥7/10), localized in  the posterior and superior area of the gleno- humeral joint, exacerbated by passive and active abduction of the arm  of more than 90 degrees. No  swelling, peri- articular redness, or joint deformity were present. +e pain appeared to  be somatic  in  nature, with  no  neuropathic features such as allodynia, paresthesia, burning sensation, or changes of the skin color. X-ray  films and magnetic reso- nance images showed signs compatible with postinfectious arthritis including  osteophytes in the inferior and internal area of the humeral head (Figure 1).

We performed diagnostic ultrasound-guided injection of the suprascapular nerve with bupivacaine 0.125% 6 ml and dexamethasone 4 mg resulting in complete pain relief for 15 days, returning to baseline severe pain scores afterwards. Given  the favorable result of the diagnostic injection we decided to perform PRF  of the suprascapular nerve.

+e procedure was performed in  the operating room with the patient seated and monitored by an anesthesiolo-

gist. Sedation was not required, and the patient tolerated the procedure   well.   A    high-frequency   linear    transducer (10–15 Hz)  was placed parallel and cephalad to the spine of the  scapula  (Figure  2(a)).  +e probe  was  moved  from cephalad to caudad until  the trapezius and supraspinatus muscles were identified. +e suprascapular nerve was identified as a hyperechogenic structure in the suprascapular fossa deep to  the superior  transverse scapular  ligament (Figure 2(b)). After skin infiltration with 3 ml of lidocaine

1%, a 10 cm radiofrequency  needle, with a 10 mm active tip, was inserted in  plane with the ultrasound beam and ad- vanced to reach the proximity to the nerve. A nerve stim- ulator was used as an additional nerve-finding modality. Sensitive stimulation (50–100 Hz  at 0.4 Volts)  elicited par- esthesia in  the posterior aspect of  the shoulder. Motor stimulation (2 Hz at 0.5 V) elicited muscle contraction of the supraspinatus and  infraspinatus  muscles. After  adminis- tration of 2 ml  of lidocaine 1%, PRF  was applied to the suprascapular nerve at 45 V 42°C, in 2 cycles of 120 seconds.

+e procedure was well-tolerated. After 10 mins, the patient related complete resolution of the pain  and was able to perform a full  range of  shoulder motions. She was dis- charged  home  with  the instructions  to  use  NSAIDs  as needed. +e patient presented for follow-up appointments at 1, 3, and 6 months and reported only mild intermittent pain that responded to NSAIDs.

3. Discussion

+is case report suggests that PRF may be considered for the management of chronic  shoulder pain  in  children  when conservative treatment and intra-articular injections of local anesthetic and steroids fail. In our case, a successful response was evidenced by an increased range of motion and im- provement of pain scores, consistent with the adult literature [7, 9–16]. After a single treatment, the pain was manageable with minimal analgesic requirements at the 6-month follow- up.

+e suprascapular nerve originates from the superior trunk of the brachial plexus. It provides 70% of the sensory innervation  of  the shoulder supplying  the posterior and superior aspect of the glenohumeral joint, the joint capsule, and  the acromioclavicular  joint.  It  also  provides  motor innervation to the supra- and infraspinatus muscles [17].

+ere are concerns about using radiofrequency in children because of the potential risks of nerve injury that

may cause a permanent loss of function at an early age. However, several studies in adults have reported the safety of this technique making this treatment attractive. +e injury caused by PRF  has a selective effect on small sensory fibers, A-δ  and C-fibers  [8–11]. It  has been postulated that RF causes rectification of Na+  and K+  channels leading to a depolarization state which inhibits  neural cells from reaching  the  action  potential  threshold  in  response to stimuli,  therefore decreasing the neural  transmission  of painful sensations and ectopic discharges [18–21].

Ultrasound guidance offers the advantage of real-time imaging of the nerve and needle guidance, thus decreasing the  potential for  pneumothorax and  vascular  puncture, without the need of radiation exposure for the patients and personnel.

+e decision to perform this procedure despite limited previous experience in children was taken considering the

low  risk  potential and  the possible benefits of  avoiding surgery in view of the failed previous therapies. Procedural interventions in  pediatrics are generally performed with scarce evidence and based on adult experience. +e positive results of this case report suggest that PRF may be effective in children and could be considered if the potential benefits outweigh the risks when noninvasive treatments fail.

Conflicts of Interest

+e authors declare that they have no conflicts of interest.

Acknowledgments

+e authors thank Dr. Navil Sethna, MD, for his assistance in reviewing the earlier draft and writing of the manuscript.

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