Dynamic Ultrasonography for Supinator Syndrome: A Case Report

Abstract

Posterior interosseous neuropathy resulting from compression in the radial tunnel, also known as supinator syndrome, is usually diagnosed by clinical assessment and electrodiagnostic testing. 1,2 In the past decade, high-resolution ultrasonography has been applied to aid the diagnosis of entrapment neuropathies such as carpal tunnel syndrome and cubital tunnel syndrome. 3 In this case report, we present how dynamic ultrasonography was used to assist in the diagnosis and treatment of supinator syndrome.A 58-year-old right-handed man came to our clinic complaining of progressive left finger drop over the previous 3 to 4 months. He had no history of trauma or repetitive upper arm activities, nor did he have any neck, shoulder, or upper limb pain. His medical history included type 2 diabetes mellitus, hypertension, and dyslipidemia. Family history yielded no relevant details. On physical examination, he had full muscle strength for flexion in the left fingers and wrist; however, the muscle strength for extension of the left wrist was grade 4 with radial deviation and the muscle strengths for extension of the left second, third, fourth, and fifth fingers were grades 2, 2, 0, and 0, respectively. No obvious muscle atrophy or sensory impairment was found.The deep tendon reflexes of the biceps, brachioradialis, and triceps were normal. The Spurling test was negative.Cervical spine X-ray and magnetic resonance imaging showed mild foraminal narrowing at the left C3/4 level, mild spinal stenosis at the C3-T1 levels without obvious root or cord compression, and imaging of the roots showed no signs of an inflammatory disorder. Electrodiagnostic testing revealed normal conduction velocity with low-amplitude compound muscle action potential without conduction block between forearm and elbow in a left radial motor study, and superficial radial sensory tests were normal. In addition, no evidence of conduction block was found in other arm nerves. A blood test showed normal liver and renal function, but the glycated hemoglobin level was 8.8%. The patient admitted that he did not take oral hypoglycemic agents regularly.Ultrasonography was performed with an 18-MHz linear array transducer (Acuson S2000 Ultrasound System; Siemens, Munich, Germany). The probe was placed in parallel to the posterior interosseous nerve (PIN) and the PIN was examined with the forearm in the pronated and supinated positions, bilaterally, as shown in Figure 1. Compared with the right side, the left PIN showed marked compression and angulation by the superficial head of the supinator muscle in the supinated position. In-plane ultrasound-guided PIN hydrodissection was performed with a mixture of 0.5 ml 50% glucose water and 4.5 ml 1% xylocaine ( Figure 2). The patient was also instructed to take oral hypoglycemic agents regularly and avoid strenuous or repetitive forearm activities. After treatment, the patient went abroad; hence, follow-up was carried out a month and a half later. He received no further treatment during this period. On manual muscle test, t...

Deep branch of the radial nerve: effect of pronation/supination on longitudinal nerve alignment

“…We agree with this statement, and in our study, we went further, quantifying the nerve’s angulation and demonstrating the existence of different patterns of nerve deflection with forearm rotation. Chen and Wang demonstrated the clinical application of forearm pronation and supination with HRUS in a case report of supinator syndrome [ 17 ].…”

Efficacy of 5% Dextrose Water Injection for Peripheral Entrapment Neuropathy: A Narrative Review

“…Chen et al [57] reported a 58-year-old man with drop finger for 3-4 months (the muscle strength of the left second and third fingers was 2, and that of the fourth and fifth fingers was 0) diagnosed with supinator syndrome. They performed a single ultrasoundguided PIT with 5 mL D5W to dissect the posterior interosseous nerve.…”