The Ulnar Nerve After Surgical Transposition: Can Sonography Define the Reason of Persisting Neuropathy?

Ulnar nerve neuropathy is mainly caused by compression at the level of the cubital tunnel. Two main approaches are currently known for the surgical treatment of this condition: decompression of the nerve in its usual position or transposition to the ulnar flexor side. This study was performed to define the usefulness of ultrasound in patients with persisting symptoms after ulnar nerve transposition.

We present the data of 8 subjects with persisting symptoms after nerve transposition due to compressive neuropathy. The cross-section areas (CSA) and texture changes were recorded. Each ulnar nerve was divided into 6 segments - 3 segments at the proximal pass and 3 segments at the distal pass through the subcutaneous fascia.

Texture changes were recorded in 4.6 (76.7 %)  ± 1.2 and outer nerve sheath blurring in mean 4.1 (68.3 %)  ± 1.1 of the segments. Caliber changes were found in the course of the nerve based on the 6 segments: A mean CSA of 7.45  mm²  ±  2.24 was found proximal to the upper fascial passage (PUF), a mean CSA of 11.96  mm²  ±  3.61  at the upper fascial passage (UF), a mean CSA of 11.49  mm²  ±  8.16 distal to the upper fascial passage (DUF), a mean CSA of 10.84  mm²  ±  4.73 proximal to the lower fascial passage (PLF), a mean CSA of 12.12  mm²  ±  5  at the lower fascial passage (LF), and a mean CSA of 7.89  mm²  ±  3.42 distal to the lower fascial passage (DLF). All transposed nerves presented relevant kinks at the UF, 6 nerves presented relevant kinks at the LF.

In cases of secondary ulnar neuropathy after nerve transposition, ultrasound can reliably assess the actual "situation" of the nerve and thus at least ease the decision for secondary surgery.