Severe Focal Abdominal Weakness Presenting as an Abdominal Hernia.

A 56-year-old female presented to her primary care physician (PCP) with years of a chronic right-sided abdominal mass. Initial imaging with an abdominal computed tomography (CT) did not reveal a true hernia but did show significant abdominal muscle wasting, causing outpouching of her abdominal wall. General surgery was consulted and noted a lack of response of the abdominal musculature on the right side when asked to brace her abdomen, prompting referral to physiatry to evaluate a potential neuromuscular source of the mass. Physical examination revealed a protuberant abdomen on the right greater than the left, anteriorly rounded shoulders, and raised scapulae bilaterally. Electrodiagnostic studies (EDX) revealed scattered atypical myotonic discharges and low-amplitude motor unit potentials (MUPs). While these findings were not specific to facioscapulohumeral dystrophy type 1 (FSHD1), her clinical picture prompted genetic testing elucidating a contraction in the D4Z4 gene, consistent with FSHD1. The patient had been managing with supportive therapies, including an abdominal truss. While abdominal weakness is a common feature of FSHD1, it is rarely the main presenting feature. Knowledge of the highly variable and asymmetrical presentations of this disorder may allow a more timely diagnosis and better prognosis while avoiding unnecessary testing.