Utilization Of Leg Mri As An Additional Diagnostic Tool In The Assessment Of Foot Drop

Nerve conduction studies (NCSs) in conjunction with electromyography (EMG) are the traditional diagnostic methods to evaluate foot drop. Sometimes the diagnostic yield of EMG/NCS can be compromised by underlying confounding pathology and overall this is an invasive procedure. MRI can provide a detailed assessment of muscle and nerve and it can identify neurogenic changes in different muscles. In the correct context, MRI can be used to explore the underlying pathophysiology of foot drop. In this study, we described the diagnostic value of MRI in patients with foot drop. Patients who were assessed for foot drop in the inpatient and/or outpatient setting were identified via a retrospective chart review; nine cases in which MRI of the leg provided valuable diagnostic and/or prognostic information were selected for further study and comparison (mean age, 52 years; age range, 13-87 years; 4 female patients, 5 male patients). In two cases, where EMG was suggestive of possible peroneal neuropathy across the fibular head without significant denervation changes on needle EMG, MRI leg did not show any edema in peroneal innervated muscles; in these cases, recovery was rapid and complete. Five cases of peroneal neuropathy with significant axon loss based on EMG, were noted to have edema only in the peroneal innervated muscles in MRI; in these cases, recovery was limited with the exception of one case in which nerve decompression was performed. In one case with clinical suspicion of peroneal neuropathy, EMG was suggestive of more diffuse changes, and MRI reflected muscle edema in all leg muscles. The final case had isolated peroneus longus atrophy on clinical examination, however, MRI reflected edema in L5 innervated muscle groups, and EMG confirmed this MRI finding. In conclusion, MRI leg can be a useful diagnostic and prognostic tool in selected cases of foot drop. Further study can help to better understand the potential of MRI in such cases