Reinterpretation of Electrodiagnostic Studies and MRIs in Patients with Non-Traumatic “Isolated” Anterior Interosseous Nerve Palsy

Andrés A. Maldonado, Kimberly K. Amrami, Michelle M Mauermann, Robert J. Spinner

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INTRODUCTION:: Different hypotheses have been proposed for the pathophysiology of anterior interosseous nerve (AIN) palsy: compression, fascicular constriction or nerve inflammation (Parsonage-Turner Syndrome). We hypothesized that critical reinterpretation of electrodiagnostic studies (EDX) and MRIs of patients with a diagnosis of AIN palsy could provide insight into the pathophysiology and treatment. MATERIALS AND METHODS:: A retrospective review was performed of all patients with a diagnosis of non-traumatic AIN palsy and an upper extremity MRI performed at our institution. The original EDX and MRI reports were re-interpreted by a neuromuscular neurologist and musculoskeletal radiologist respectively, both blinded to our hypothesis. RESULTS:: One hundred and twenty-three patients were identified with non-traumatic AIN palsy. Of these, 16 patients met the inclusion criteria as having “isolated” AIN palsy. Physical examination revealed weakness in muscles not innervated by the AIN in 5 cases (31%) and EDX abnormalities not related to the AIN were found in 9 cases (60%). The initial MRI report described atrophy in muscles not innervated by the AIN or nerve enlargement different from the AIN in 8 cases (50%). In all cases, reinterpretation of the MRIs demonstrated atrophy in at least one muscle not innervated by the AIN and did not reveal any evidence of compression of the AIN. CONCLUSION:: All patients in our series with presumed isolated AIN palsy had MRI evidence of a more diffuse muscle involvement pattern, without any radiologic signs of nerve compression of the AIN branch itself. These data strongly support an inflammatory pathophysiology.

Original languageEnglish (US)
JournalPlastic and Reconstructive Surgery
StateAccepted/In press - Jul 5 2016


ASJC Scopus subject areas

  • Surgery

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