Prevalence of tarsal tunnel syndrome in a cohort of Egyptian Rheumatoid arthritis patients

Background: Tarsal tunnel syndrome (TTS) is a neuropathy caused by compression of the posterior tibial nerve or its distal branches beneath the flexor retinaculum. Rheumatoid arthritis (RA) is recognized as a possible underlying cause. Purpose: to investigate the prevalence of TTS among Egyptian cases with RA and explore its correlation with disease activity and severity. Subjects and methods: the study involved 50 RA cases and 30 healthy controls. All participants underwent clinical assessment, nerve conduction studies, and ultrasound measurement of the posterior tibial nerve cross-sectional area (CSA). Disease severity and activity were assessed using the Larsen score and DAS28, respectively. Laboratory investigations included CBC, ESR, CRP, AST, ALT, RF, and anti-CCP antibodies. Results: 4% of the studied cases had bilateral TTS, 14% had unilateral medial TTS, and 8% had unilateral lateral TTS. Posterior tibial nerve CSA was significantly higher among R.A cases than control but there were no significant correlations between posterior tibial nerve CSA and nerve conduction studies (P >.05). No correlation between the disease activity and severity with electrophysiological TTS parameters (P >.05). Conclusions: Peripheral nerve involvement, particularly TTS, is relatively frequent in RA-affected feet, regardless of the underlying disease's activity or severity. Four percent of RA cases had bilateral TTS, while 14% had unilateral medial TTS, and 8% had unilateral lateral TTS. Neuromuscular ultrasound may serve as a valuable adjunct to electrophysiological testing in the diagnosis of TTS.