Tarsal Tunnel Syndrome: An Ultrasound Pictorial Review doi.org/10.1002/jum.15793 Tarsal tunnel syndrome (TTS) is an entrapment neuropathy caused by compression of the posterior tibial nerve or its branches as they pass beneath the flexor retinaculum at the medial ankle. Clinical presentation is often nonspecific, including burning pain, paresthesia, numbness, and discomfort worsened by activity or at night. Diagnosis is challenging because symptoms can mimic other conditions, and conventional tests such as the Tinel sign and plain radiographs lack specificity. High-resolution ultrasound has emerged as a key diagnostic tool because of its accessibility, low cost, and superior spatial resolution compared with MRI. It allows dynamic and comparative studies, identification of nerve compression sites, and evaluation in weight-bearing positions. Ultrasound can also help differentiate causes, guide interventions, and complement electrophysiological testing. Etiologies of TTS are varied and include bone and joint abnormalities (such as hindfoot valgus, coalitions, spurs), accessory ossicles, synovitis, rheumatoid arthritis, and post-traumatic changes. Expansile lesions like ganglion cysts, lipomas, and nerve sheath tumors are also implicated. Metabolic conditions such as diabetes, gout, hyperlipidemia, and hypothyroidism can predispose to nerve enlargement or compression. Muscular causes include hypertrophy or supernumerary muscles (accessory soleus, accessory flexor digitorum, peroneocalcaneus internus). Tendinopathy, tenosynovitis, vascular abnormalities, and iatrogenic factors like surgical hardware or scarring are additional contributors. Conservative management includes rest, anti-inflammatory therapy, orthotic support, and physiotherapy, with surgery reserved for refractory cases depending on the underlying pathology. Awareness of the diverse causes and ultrasound findings is essential to ensure timely diagnosis, prevent morbidity, and improve patient outcomes. #POCUS #ultrasound #ecografia #ankle