title: Ultrasound findings after surgical decompression of the tarsal tunnel in patients with painful diabetic polyneuropathy: a prospective randomized study.
abstract: OBJECTIVE
  It has been hypothesized that the development of diabetic polyneuropathy (DPN) is due to swelling of the nerve, as well as thickening and stiffening of the surrounding ligaments, causing chronic compression of nerves. We aimed to examine the effect of surgical decompression of the tibial nerve on the mean cross-sectional area (CSA).
  
  
  METHODS
  We performed a randomized controlled trial of 42 subjects with painful DPN diagnosed using the Diabetic Neuropathy Score. A computer randomized for the surgery arm of the study. A control group consisting of 38 healthy subjects was included. An experienced sonographer measured the CSA and thickness-to-width (T/W) ratio of the tibial nerve, as well as the thickness of the flexor retinaculum.
  
  
  RESULTS
  CSA is significantly larger in patients with painful DPN (8.4 ± 3.9 mm(2)) than in control subjects (6.4 ± 1.3 mm(2)), P = 0.007. The T/W ratio in patients with painful DPN is 0.64 and in control subjects 0.59, P = 0.03. Patients with DPN have a significantly thicker retinaculum (1.07 mm) than control subjects (0.84 mm), P < 0.001. Mean follow-up was 28.2 weeks (range 23-45). Difference between baseline and follow-up in the operated leg was 1.49 mm(2) and in the control leg 1.81 mm(2), P = 0.674.
  
  
  CONCLUSIONS
  Decompression of the tibial nerve does not result in a significant difference between baseline and follow-up in CSA using ultrasound between the operated and control leg. Ultrasound measurements show a significantly increased CSA, a significantly thicker retinaculum, and a significantly increased T/W ratio in patients with painful DPN compared with healthy control subjects. Clinical trial reg. no. NTR2344, www.trialregister.nl.
authors.affiliation: Corresponding author: Marita E.L. Schouten, maritaschouten@hotmail.com.
authors.forename: Joanne F M
authors.initials: JF
authors.lastname: Macaré van Maurik
authors.forename: Marita E L
authors.initials: ME
authors.lastname: Schouten
authors.forename: Iris
authors.initials: I
authors.lastname: ten Katen
authors.forename: Mireille
authors.initials: M
authors.lastname: van Hal
authors.forename: Edgar J G
authors.initials: EJ
authors.lastname: Peters
authors.forename: Moshe
authors.initials: M
authors.lastname: Kon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019299:Decompression, Surgical / Q000379:methods*; D003922:Diabetes Mellitus, Type 1 / Q000000981:diagnostic imaging / Q000601:surgery*; D003924:Diabetes Mellitus, Type 2 / Q000000981:diagnostic imaging / Q000601:surgery*; D003929:Diabetic Neuropathies / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013641:Tarsal Tunnel Syndrome / Q000000981:diagnostic imaging / Q000601:surgery; D013979:Tibial Nerve / Q000000981:diagnostic imaging / Q000601:surgery*; D014463:Ultrasonography; D055815:Young Adult