Arnold-Chiari Malformation Type I Presenting With Bilateral Scapular Winging.

Bilateral scapular winging is a rare and atypical manifestation of Arnold-Chiari malformation type 1 (ACM1). We report a case of ACM with extensive syrinx formation, presenting with progressive bilateral proximal upper extremity weakness, bilateral scapular winging, and segmental hypesthesia and reduced thermesthesia over the bilateral C2-C8 dermatomal levels. The patient was successfully treated with surgical decompression and syringosubarachnoid shunting. This unusual presentation of ACM1 emphasizes the need to consider central nervous system pathologies in the differential diagnosis for bilateral scapular winging.