title: High-resolution MR neurography: evaluation before repeat tarsal tunnel surgery.
abstract: OBJECTIVE
  The purpose of this study was to retrospectively determine the accuracy of high-resolution MR neurography (MRN) in presurgical evaluation before repeat tarsal tunnel surgery.
  
  
  METHODS
  Ten MRN studies of nine patients (one man, eight women; mean age, 44.4 years; range, 23-67 years) who had been referred to a peripheral nerve specialist because of persistent symptoms after tarsal tunnel release were reviewed. The MRN findings studied included presence and location of focal fibrosis, presence or absence of nerve abnormality, location of nerve abnormality, and presence of neuroma formation and regional muscle denervation. The diagnostic accuracy of MRN in detection of posterior tibial nerve, medial plantar nerve, and lateral plantar nerve injury was calculated with clinical and intraoperative findings as the reference standards.
  
  
  RESULTS
  Nine of 10 MRN studies (90%) had findings of nerve reentrapment related to focal fibrosis. Injured nerves were reliably visualized with MRN in all patients. MRN had a sensitivity of 77% for posterior tibial nerve, 100% for medial plantar nerve, and 100% for lateral plantar nerve injury, and the overall accuracy was 86%. The sensitivity of MRN was 91% for the presence of focal fibrosis affecting the three nerves and 67% for neuroma detection. Regional muscle denervation was better evaluated on MRN studies than at surgery. Smaller (1-3 mm) abnormal cutaneous nerve branches were better seen at surgery.
  
  
  CONCLUSIONS
  MRN yields accurate morphologic information about the location and extent of nerve injury after failed tarsal tunnel release and facilitates preoperative diagnosis.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Johns Hopkins Hospital, Baltimore, MD 21287, USA.
authors.forename: Avneesh
authors.initials: A
authors.lastname: Chhabra
authors.forename: Ty K
authors.initials: TK
authors.lastname: Subhawong
authors.forename: Eric H
authors.initials: EH
authors.lastname: Williams
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Wang
authors.forename: Shar
authors.initials: S
authors.lastname: Hashemi
authors.forename: Shrey K
authors.initials: SK
authors.lastname: Thawait
authors.forename: John A
authors.initials: JA
authors.lastname: Carrino
mesh_terms: D000328:Adult; D000368:Aged; D000842:Ankle / Q000473:pathology / Q000601:surgery*; D001178:Arthroplasty / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010525:Peripheral Nerves / Q000473:pathology*; D010523:Peripheral Nervous System Diseases / Q000209:etiology* / Q000473:pathology*; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D055815:Young Adult