Can MR neurography of the common peroneal nerve predict a residual motor deficit in patients with foot drop?

• Published in: Skeletal radiology Vol. 52; no. 4; pp. 751 - 761
• Main Authors: Daniels, Steven P., Ross, Andrew B., Sneag, Darryl B., Gardon, Stephanie N., Li, Geng, Hanna, Amgad S., Tuite, Michael J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2023; Springer; Springer Nature B.V
• Subjects: Ankle; Atrophy; Decompression; Feet; Humans; Imaging; Magnetic Resonance Imaging - methods; Male; Medical colleges; Medical research; Medicine; Medicine & Public Health; Medicine, Experimental; Middle Aged; Muscle Weakness - diagnostic imaging; Muscles; Nerves; Neurology; Neuropathy; Nuclear Medicine; Orthopedics; Pathology; Patients; Peroneal nerve; Peroneal Nerve - diagnostic imaging; Peroneal Neuropathies - diagnostic imaging; Peroneal Neuropathies - surgery; Public health; Radiology; Retrospective Studies; Scientific Article; Statistical analysis; Surgery; Peripheral nerve; Peripheral nerve injury; MR neurography; Common peroneal nerve
• ISSN: 0364-2348; 1432-2161
• DOI: 10.1007/s00256-022-04214-2

Objective To determine if MR neurography of the common peroneal nerve (CPN) predicts a residual motor deficit at 12-month clinical follow-up in patients presenting with foot drop. Materials and methods A retrospective search for MR neurography cases evaluating the CPN at the knee was performed. Patients were included if they had electrodiagnostic testing (EDX) within 3 months of imaging, ankle and/or forefoot dorsiflexion weakness at presentation, and at least 12-month follow-up. Two radiologists individually evaluated nerve size (enlarged/normal), nerve signal (T2 hyperintense/normal), muscle signal (T2 hyperintense/normal), muscle bulk (normal/Goutallier 1/Goutallier > 1), and nerve and muscle enhancement. Discrepancies were resolved via consensus review. Multivariable logistical regression was used to evaluate for association between each imaging finding and a residual motor deficit at 12-month follow-up. Results Twenty-three 3 T MRIs in 22 patients (1 bilateral, mean age 52 years, 16 male) met inclusion criteria. Eighteen cases demonstrated common peroneal neuropathy on EDX, and median duration of symptoms was 5 months. Six cases demonstrated a residual motor deficit at 12-month follow-up. Fourteen cases underwent CPN decompression (1 bilateral) within 1 year of presentation. Three cases demonstrated Goutallier > 1 anterior compartment muscle bulk. Multivariable logistical regression did not show a statistically significant association between any of the imaging findings and a residual motor deficit at 12-month follow-up. Conclusion MR neurography did not predict a residual motor deficit at 12-month follow-up in patients presenting with foot drop, though few patients demonstrated muscle atrophy in this study.