What is the role of imaging studies in the evaluation of plantar and digital nerve entrapments?

Updated: Oct 15, 2019
  • Author: Minoo Hadjari Hollis, MD; Chief Editor: Thomas M DeBerardino, MD  more...
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Answer

In rare, complex situations, ultrasonography and MRI may be helpful for defining interdigital neuritis (also known as Morton neuroma, Morton metatarsalgia, interdigital neuroma, or interdigital nerve compression). [43] The accuracy of these studies, however, varies significantly and depends on multiple factors, including the MRI machine, the technician and the technique, and the interpreting radiologist or orthopedic surgeon.

Ultrasonography reveals a hypoechoic, ovoid mass parallel to the long axis of the metatarsal. Ultrasonography can also be used to diagnose other pathologic conditions in the forefoot, such as bursitis and metatarsophalangeal (MTP) joint effusion. Redd et al reported that this study was 95% sensitive in the detection of webspace abnormality but could not clearly distinguish interdigital neuritis from an associated mass (eg, mucoid degeneration in the adjacent loose connective tissue). [44]

In a study by Quinn et al, ultrasonography revealed the diagnosis in 85% of cases in which it was suspected, [45] though the ability to detect neuromas shorter than 5 mm was limited. Terk et al reported on MRI with T1- and T2-weighted sequences, along with a combination of fat suppression and the administration of gadopentetate dimeglumine. [46] Williams et al showed that T1-weighted axial and coronal images obtained with an axial, fast spin-echo (FSE), T2-weighted sequence depict neuromata more consistently than other methods do.


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