Introduction

Pronator syndrome is defined as median nerve compression in the forearm causing isolated sensory alternation, which could be difficult to differentiate with carpal tunnel syndrome. Conservative treatment was reported effective in most of the patients. However, when space-occupying lesion is present or a several-month conservative treatment fails, surgical decompression may be indicated.



Case Presentation

We present two cases of pronator syndrome, who received surgical decompression.

Case 1

A 49-year-old female suffered from progressive bilateral hand numbness for years, more severe at left side. The numbness was noted over radial side four digits, persisted at left hand and triggered by exercise at right hand. She received conservative rehabilitation at other hospital for 3 months, but the symptoms persisted. In our clinic, physical exam revealed the numbness also noted at thenar area of left volar hand. The distance of two-point discrimination test were all 6 mm. NCV and EMG study revealed bilateral median entrapment neuropathy. Surgical decompression with pronator teres release and carpal tunnel release was performed. Intraoperatively, compression of median nerve was noted at bicipital aponeurosis (lacertus fibrosus) and arch of flexor digitorum superficialis. At postoperative 4 months follow-up, the numbness relieved completely.

Case 2

A 64-year-old female suffered from left hand numbness for years. She had received carpal tunnel release surgery twice at other hospital and cervical herniated intervertebral disc surgery once, but the symptoms persisted. According to the patient, left thenar area numbness was noted during motorcycling, but relieved at rest. There was no weakness of opposition doing OK sign. The two-point discrimination test was more than 12 mm at thumb both side, and around 7 mm at index and long fingers. NCV and EMG study findings suggest left median neuropathy at the forearm segment. MRI revealed unremarkable pronator teres and median nerve. Surgical decompression of median nerve and ulnar nerve was performed with pronator teres release, carpal tunnel release and Guyon’s canal release. Compression of median nerve between two head of pronator teres muscle was noted intraoperatively. At postoperative clinic follow-up, numbness relieved completely with the improvement of two-point discrimination test, especially at thumb.



Discussion

Pronator syndrome referred to compression of median nerve at antecubital area which could be caused by multiple structures. We review the literatures on the surgical intervention and surgical approach of decompression.