Proposed Sonographic Criteria for the Diagnosis of Idiopathic Tarsal Tunnel Syndrome

Abstract

ObjectiveTo propose new sonographic criteria for the diagnosis of idiopathic tarsal tunnel syndrome (TTS). DesignProspective case-control study. SettingAcademic referral center. ParticipantsAdult healthy volunteers (n=17) and adult patients (n=14) with electrodiagnostically proven idiopathic TTS (mean age, 43.4±8.7y; height, 161.4±7.0cm; weight, 90.6±13.9kg) (N=31). The exclusion criteria were patients with diabetes, neurological disorders, associated ankle and/or foot disorders, electrodiagnostic evidence of a widespread lesion, or feet that were electrophysiologically negative for TTS or with structural abnormalities detected via ultrasound imaging. InterventionsNot applicable. Main Outcome MeasuresTibial nerve CSA at the proximal tarsal tunnel, tibial nerve CSA within the tunnel, within tunnel-to-proximal tunnel CSA ratio. ResultsThere was a significant difference in the within tunnel CSA and within tunnel-to-proximal tunnel CSA ratio between the TTS group and controls (P=.002 and P=.001, respectively). The optimum cutoff value was 19mm2 for the within tunnel CSA and 1 for the within tunnel-to-proximal tunnel CSA ratio. Sensitivities were 61% and 74%, respectively. ConclusionsThe within tunnel-to-proximal tunnel CSA ratio and the within tunnel CSA are the most accurate sonographic parameters and can be helpful in the assessment of idiopathic TTS.