Brachial Plexus Neuritis, a Rare Presentation of Parsonage-Turner Syndrome

Suvar T*, Choi H and Arambulo M

Department of Anesthesiology, University of Arkansas for Medical Sciences, USA

*Corresponding author: Suvar T, Department of Anesthesiology, University of Arkansas for Medical Sciences, USA

Received: November 22, 2017; Accepted: December 05, 2017; Published: December 12, 2017

Abstract

Parsonage-Turner syndrome is a condition involving the brachial plexus and symptoms include sudden onset of pain followed by weakness and sensory symptoms. Its pathogenesis is not fully understood, but it is thought to be inflammatory in origin.

A 78-year-old female presented with a 7-month history of pain and 5-month history of weakness in her left wrist and hand. Four months after the symptom onset, patient underwent a carpal tunnel release surgery, which only aggravated the pain and limited her left hand movement. She reported the pain as sharp, burning, and stabbing that had become progressively worse and constant.

The rare but plausible diagnosis in her case is Parsonage-Turner syndrome. With mild improvement in flexion and extension of the forearm, Parsonage- Turner syndrome is highly likely.

Keywords: Parsonage-Turner Syndrome; Brachial plexus neuritis; Neuralgic amyotrophy

Introduction

Parsonage-Turner syndrome, also known as neuralgic amyotrophy or paralytic brachial neuritis, is an inflammatory disorder involving the brachial plexus. Classic clinical manifestation starts with severe pain followed by weakness and sensory symptoms, usually in the upper and/or middle brachial plexus. The pathogenesis is not well-defined, but immune-mediated process is thought to be a possible cause [1,2].

We report a case of a 78-year-old female with complex medical history who presented with pain in her left arm proceeded by a decreased motor function. Her physical exam was positive for weakness in her left arm, as well as allodynia and hyperalgesia. Diagnostic studies included EMG, MRI, and MR Neurography, and results were suggestive of Parsonage-Turner syndrome. Atypical aspects of this case and diagnostic challenges are also discussed.

Case Presentation

A 78-year-old female presented with a 7-month history of pain and 5-month history of weakness in her left wrist and hand. Patient’s past medical history included coronary artery disease status post coronary artery bypass graft, carpal tunnel release surgery, breast cancer in remission treated by mastectomy and chemotherapy, sealed PFO, multiple strokes, and thoracic aortic aneurysm.

Patient reported that she had a fall one month prior to symptom onset, injuring her elbow and placing her in cast for several days. Shortly after the fall, she was also involved in a motor vehicle crash and presented to an outside hospital emergency department for severe pain, which radiated from her left shoulder and scapula to her arm. In the ER, MRI studies then showed normal brachial plexus with cervical spine radiculitis. Four months after the symptom onset, patient underwent a carpal tunnel release surgery, which only aggravated the pain and limited her left hand movement.

On her presentation, she reported the pain as sharp, burning, and stabbing that had become progressively worse and constant. The location of the pain was beginning at the level of her left shoulder and radiating down to her fingertips. Pain was worsened by walking and having her left arm hang beside her by gravity. Patient was prescribed Oxycodone 15mg twice daily, Gabapentin 300mg four times daily, and prednisone. She had already been seen by neurosurgery, neurology, vascular surgery, and orthopedics. Vascular surgery had ruled out vascular causes of her pain especially associated with thoracic aortic aneurysm. She also had undergone 4 weeks of occupational therapy with no clinical improvement. On physical exam, she was found to have 1/5 strength with left elbow flexion and extension, wrist flexion and extension, finger abduction, and hand grip. Shoulder abduction strength was 3/5 and only abducted to 30 degrees. Reflexes in the biceps, brachioradialis, and triceps were 1+. Radial pulses were palpable bilaterally. Her right upper extremity strength was 5/5. There was diminished sensation to light touch and pinprick in the entire left hand, as well as the left lateral forearm. Physical exam was also positive for allodynia and hyperalgesia of the left upper extremity. EMG studies showed no residual innervation by the left median nerve, as well as focal slowing of the median nerve from the upper humerus to the elbow. Ischemic neuropathy of multiple nerves was also seen. MR neurography of the brachial plexus showed diffuse abnormality, with diffuse thickening from C4 to C8 through the entire visualized brachial plexus. Cervical spine MRI showed no acute parenchymal signal abnormality. On follow up with the patient, one month after her office visit, she noted to have improved flexion and extension of her forearm. Wrist extension and flexion was limited and the ability to move her fingers as well. The pain persisted from the middle of her arm and continued in the same nature, radiating pain towards her fingertips.

Discussion

Parsonage-Turner syndrome is a condition involving the brachial plexus. Its pathogenesis is not fully understood, but it is thought to be inflammatory in origin. Typical symptoms include sudden onset of pain followed by weakness and sensory symptoms. Weakness distribution usually involves one nerve, but bilateral involvements, as well as multiple nerve involvement are possible [1]. Multiple etiology of this syndrome has been reported including infection, minor surgery, and post trauma [2-4]. Cases of neuralgic amyotrophy occurring after corticosteroid injection and influenza vaccination have also been reported [5,6]. Differential for upper extremity pain is broad; in our case, the differential included cervical spine radiculopathy, degenerative disc disease, mononeuritis multiplex, vascular cause, complex regional pain syndrome secondary to surgical intervention, and Parsonage-Turner syndrome.

Diagnosis usually involves EMG, MRI, and MR Neurography. EMG typically shows wide denervation, usually in individual muscles not sharing root innervations [2,4]. In the case of our patient, she had no motor function in forearm and hand flexion or extension. Biceps, triceps, brachioradialis, intrinsic muscles of the hand were affected, revealing C5-T1 nerve roots to be affected. MRI may be normal in the acute phase [7]. Scalf et al [8]. Recommend further studies are needed to understand the time course of MRI changes in this syndrome. MR Neurography may provide diagnostic benefits over MRI, and allow for earlier diagnosis [2,9]. Treatment for this syndrome involves physical therapy and analgesic medications [1,2,4]. Parsonage-Turner syndrome is often self-limited and can last as long as weeks to years.

There is high clinical variability seen in Parsonage-Turner syndrome, which may contribute to misdiagnosis or delay in diagnosis. Our case presents the challenge of multiple comorbidities complicating the diagnosis of Parsonage Turner syndrome. Our patient’s history of carpal tunnel surgery might have contributed to her delayed presentation to our clinic, as well as exacerbated her symptoms. Consideration of Parsonage Turner syndrome and work up with EMG and MR Neurography could have also prevented the need for a carpal tunnel release surgery for her, sparing her the cost, stress, and complications of such procedure. Her history of aortic aneurysm had also been high on the differential diagnosis but was ruled out by vascular surgeons. Concomitant disorders can also complicate diagnosis 2 as seen in our case. Our patient had evidence of degenerative disc disease on MRI, but other findings on EMG and MR Neurography support her additional diagnosis of Parsonage- Turner syndrome. Parsonage-Turner syndrome is her current working diagnosis, but definite diagnosis is heavily dependent on clinic follow up. With mild improvement in motor function of the C5-C6 nerve root distribution and no relief in pain, Parsonage- Turner syndrome is highly likely.

Written Consent Statement

The authors of this case report hereby state that the involved patient provided written consent for the report to be published.