Proposed Sonographic Criteria for the Diagnosis of Idiopathic Tarsal Tunnel Syndrome.

ABSTRACT

OBJECTIVE: To propose new sonographic criteria for the diagnosis of idiopathic tarsal tunnel syndrome (TTS). DESIGN: Prospective case-control study. SETTING: Academic referral center. PARTICIPANTS: Adult 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. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Tibial nerve CSA at the proximal tarsal tunnel, tibial nerve CSA within the tunnel, within tunnel-to-proximal tunnel CSA ratio. RESULTS: There 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 19mm(2) for the within tunnel CSA and 1 for the within tunnel-to-proximal tunnel CSA ratio. Sensitivities were 61% and 74%, respectively. CONCLUSIONS: The 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.