The neuropathic compression of the tibial nerve and/or its branches on the medial side of the ankle is called tarsal tunnel syndrome (TTS). Patients with TTS presents pain, paresthesia, hypoesthesia, hyperesthesia, muscle cramps or numbness which affects the sole of the foot, the heel, or both. The clinical diagnosis is challenging because of the fairly non-specific and several symptomatology. We demonstrate a case of TTS caused by medial dislocation of the talar bone on the calcaneus bone impacting the tibial nerve diagnosed only by ultrasound with the patient in the standing position.

Tarsal tunnel syndrome may be idiopathic or may be caused by various conditions: bone disease, thickening of the retinaculum, hematoma, or iatrogenic nerve damage; tendinopathy or tenosynovitis; the presence of supernumerary muscles such as an accessory soleus, peroneocalcaneus internus, or accessory flexor digitorum muscle; bone or joint disorders; expansile tumors or cysts; and venous aneurysm or kinking of the tibial artery. The purpose of this article is to describe and illustrate most of the causes of tarsal tunnel syndrome, as diagnosed by ultrasound, which is a practical, inexpensive method.

The axial cross-sectional area (CSA) of the tibial nerve can be measured with ultrasonography. In patients who have posteromedial tarsal tunnel syndrome (TTS), there is little information on the nerve's CSA even though this information could be useful for determining whether the nerve is damaged. This led us to carry out a case-control study in which the tibial nerve's axial CSA was measured in healthy patients and in patients with TTS.

The tibial nerve's axial CSA can be used as a diagnostic criterion for TTS.

Twenty-three patients (27 feet) (11 men, 12 women, mean age=54±14 years), who had clinical and electroneuromyography signs of TTS, were compared to 21 healthy adults (8 men, 13 women, mean age 39±10 years). An ultrasonography examination was carried out to look for a source of nerve compression, then the axial CSA of the tibial nerve was measured 10cm above the tarsal tunnel (_lCSA) and inside the tunnel itself (_ttCSA). The difference between the two measurements was then calculated: _ΔCSA=_ttCSA-_lCSA. The data were analysed using correlation tests and non-parametric tests, a multivariate linear regression and ROC tests.

A compressive cause was found by ultrasonography in 13 patients. The mean values of _ttCSA and _ΔCSA were 20.1±8.8 mm² [6-42] vs. 10.3±2.3 mm² [8-14] (p=0.0001) and 9.8±6.7 mm² [0-29] vs. -0.2±1.8 mm² [-3-4] (p<0.0001) in the patients and the controls, respectively. The differences in _ΔCSA remained significant in the multivariate analysis after adjusting for age and weight. The best threshold for _ttCSA in the TTS group was 15 mm² with 74% sensitivity and 100% specificity. The best threshold for _ΔCSA was 5mm² with 81% sensitivity and 100% specificity.

The difference in the measured axial CSA of the tibial nerve by ultrasonography between the posteromedial tarsal tunnel and 10cm above the tunnel is a key data point for the diagnosis of tarsal tunnel syndrome with and without compressive etiology.

III, diagnostic case-control study.

The straight leg raise test (SLR) is one of the most performed physical tests for mechanosensitivity and impairment of the nervous system. According to the anatomy of the tibial nerve, ankle dorsiflexion and eversion movements could be used to perform the tibial neurodynamic test (TNT). To date, no study has documented the normal responses of the TNT.

To document normal responses of the TNT in asymptomatic individuals and to investigate influences from sex and leg dominance.

A cross-sectional study with 44 asymptomatic volunteer subjects, a total of 88 lower limbs, was carried out. The range of motion (ROM), quality, and distribution of sensory responses were recorded. The hip flexion ROM was measured when subjects reported an intensity of their symptoms of 2/10 (P1) and 8/10 (P2).

The mean ROM for hip flexion at P1 was 44.22 ± 13.13∘ and 66.73 ± 14.30∘ at P2. Hip flexion was significantly greater at P2 than P1 (p< 0.001). However, it was not different between sex or limbs (p> 0.05). The descriptor of the quality of sensory responses most often used by participants was stretching (88.6% and 87.5% for P1 and P2, respectively) in the popliteal fossa and posterior calf.

This study describes the sensory responses of asymptomatic subjects resulting from the TNT. Our findings indicate that TNT responses are independent of the influence of sex or leg dominance.

The tarsal tunnel is a clinically important fibrous osseous conduit for the tibial nerve and associated tendons. It is mechanically dynamic, and normal ankle movements appear to change the tunnel shape, potentially having an impact on the tibial nerve. The objective of this study was to measure changes in the tibial nerve and tarsal tunnel dimensions in plantarflexion and dorsiflexion of the ankle joint in healthy subjects. A cross-sectional study with 13 volunteer subjects and a total of 18 records was designed. The cross-sectional area, anterior-posterior distance, transverse distance, and flattening ratio of the tibial nerve were measured by using ultrasound in plantarflexion and dorsiflexion of the ankle joint. The anterior-posterior distance of the tarsal tunnel was also measured. The tunnel anterior-posterior distance significantly increased during plantarflexion (p < .001) and decreased during dorsiflexion (p = .027) of the ankle. From plantarflexion to dorsiflexion of the ankle, the tibial nerve cross-sectional area significantly decreased (p = .035). The anterior-posterior distance also decreased significantly (p < .001), whereas the transverse distance increased (p < .001), thus decreasing the flattening ratio of the tibial nerve (p < .001). Ankle joint position determined significant changes in the shape and dimensions of the tibial nerve at the tarsal tunnel.

High-resolution ultrasonography (US) can play an important role in studying nerves, as it has several advantages. Entrapments of distal tibial nerve branches can be mapped out or diagnosed with selective anesthetic blocks, and US can guide therapeutic procedures, such as radiofrequency ablation and selective infiltrations of specific nerve branches. The aim of this study was to verify that US is an effective method for accurately locating the posterior tibial nerve and its terminal branches, such as the medial calcaneal branch, the first calcaneal branch, and the medial and lateral plantar nerves.

In this study, we analyzed the correlation between US mapping and real anatomy after cadaveric dissection, assessing the distribution and variability of the tibial nerve and its terminal branches. We used 12 fresh anatomic specimens of the foot and ankle, including the calf. A high-resolution US study of the tibial nerve and its branches was performed.

The results of the US studies of the anatomic specimens were drawn as paper diagrams and in data collection tables. Both were completed twice per anatomic specimen, first using the results of the US study and second using the results from dissection of the anatomic specimens; this approach enabled us to compare the results and verify whether the US study and the dissection correlated on the topography of the tibial nerve and its terminal branches. We found almost total agreement between the US and dissection results, with no significant differences between the evaluations.

On the basis of this work, we can conclude that high-resolution US is almost 100% effective as a tool for identifying the tibial nerve and its branches, enabling the specialist to make diagnoses or perform selective treatments on each nerve branch and even to design surgical interventions by observing the patient's anatomy before performing the dissection.

High-resolution ultrasonography of the tibial nerve is a fast and non invasive tool for diagnosis of diabetic peripheral neuropathy. Our study was aimed at finding out the correlation of the cross sectional area and maximum thickness of nerve fascicles of the tibial nerve with the presence and severity of diabetic peripheral neuropathy.

75 patients with type 2 diabetes mellitus clinically diagnosed with diabetic peripheral neuropathy were analysed, and the severity of neuropathy was determined using the Toronto Clinical Neuropathy Score. 58 diabetic patients with no clinical suspicion of diabetic peripheral neuropathy and 75 healthy non-diabetic subjects were taken as controls. The cross sectional area and maximum thickness of nerve fascicles of the tibial nerves were calculated 3 cm cranial to the medial malleolus in both lower limbs.

The mean cross sectional area (22.63 +/- 2.66 mm²) and maximum thickness of nerve fascicles (0.70 mm) of the tibial nerves in patients with diabetic peripheral neuropathy compared with both control groups was significantly larger, and statistically significant correlation was found with the Toronto Clinical Neuropathy Score (p < 0.001). The diabetic patients with no signs of peripheral neuropathy had a larger mean cross sectional area (14.40 +/- 1.72 mm²) and maximum thickness of nerve fascicles of the tibial nerve (0.40 mm) than healthy non-diabetic subjects (12.42 +/- 1.01 mm² and 0.30 mm respectively).

The cross sectional area and maximum thickness of nerve fascicles of the tibial nerve is larger in diabetic patients with or without peripheral neuropathy than in healthy control subjects, and ultrasonography can be used as a good screening tool in these patients.

Tarsal tunnel syndrome (TTS) arises from tibial nerve damage under the flexor retinaculum of the fibro-osseus tunnel at the medial malleolus. It is notoriously difficult to diagnose, as many other foot pathologies result in a similar clinical picture. We examined the additional value of nerve ultrasound in patients with tarsal tunnel syndrome confirmed by nerve conduction.

We performed a retrospective analysis of nerve ultrasound changes in electrophysiologically confirmed TTS spanning our records from 2007 to 2015.

Nine feet with TTS were identified, all of which showed abnormal nerve ultrasound findings, which in 6 feet, led to identification of the underlying cause.

This study shows that nerve ultrasound is abnormal in all cases of electrophysiologically verified TTS. The pattern of nerve abnormality is varied. This, and the fact that in the majority of patients causation was identified, suggests nerve ultrasound should form part of standard work-up for TTS. Muscle Nerve 53: 906-912, 2016.

Peripheral neuropathies are one of the most common reasons for seeking neurological care in everyday practice. Electrophysiological studies remain fundamental for the diagnosis and etiological classification of peripheral nerve impairment. The recent technological development though of high resolution ultrasound has allowed the clinician to obtain detailed structural images of peripheral nerves. Nerve ultrasound mainly focuses on the evaluation of the cross sectional area, cross sectional area variability along the anatomical course, echogenity, vascularity and mobility of the peripheral nerves. An increase of the cross sectional area, hypervascularity, disturbed fascicular echostructure and reduced nerve mobility are some of the most common findings of entrapments neuropathies, such as the carpal or cubital tunnel syndrome. Both the cross-sectional area increase and the hypervascularity detected with the Doppler technique seem to correlate significantly with the clinical and electrophysiological severity of the later mononeuropathies. Significantly greater cross sectional area values of the clinically affected cervical nerve root are often detected in cases of cervical radiculopathy. In such cases, the ultrasound findings seem also to correlate significantly with disease duration. On the other hand, multifocal cross sectional area enlargement of cervical roots and/or peripheral nerves is often documented in cases of immune-mediated neuropathies. None of the later pathological ultrasound findings seem to correlate significantly with the electrophysiological parameters or the functional disability. The aim of this review is to provide a timely update on the role of neuromuscular ultrasound in the diagnostic of the most common entrapment and immune-mediated peripheral neuropathies in clinical practice.

Posteromedial tarsal tunnel syndrome is a disorder affecting the tibial nerve or its branches. Diagnosis is established on the basis of physical examination and can be confirmed by electrophysiological evidence. However, diagnostic imaging is always required to identify the possible site of compression. High-resolution ultrasound (US) is playing an increasingly important role in the study of the nerves thanks to a series of advantages over magnetic resonance imaging, such as lower costs and widespread availability, high spatial resolution, fast examination using axial scans, dynamic and comparative studies, possibility of carrying out a study with the patient in the standing position, US Tinel sign finding, and the contribution of color/power Doppler US. We present the results obtained in a series of 81 patients who underwent US imaging between 2008 and 2013 due to posteromedial tarsal tunnel syndrome.

Peripheral nerve imaging by portable ultrasound (US) may serve as a noninvasive and lower-cost alternative to nerve conduction studies (NCS) for diagnosis and staging of diabetic sensorimotor polyneuropathy (DSP). We aimed to examine the association between the size of the posterior tibial nerve (PTN) and the presence and severity of DSP.

We performed a cross-sectional study of 98 consecutive diabetic patients classified by NCS as subjects with DSP or control subjects. Severity was determined using the Toronto Clinical Neuropathy Score. A masked expert sonographer measured the cross-sectional area (CSA) of the PTN at 1, 3, and 5 cm proximal to the medial malleolus.

Fifty-five patients had DSP. The mean CSA of the PTN in DSP compared with control subjects at distances of 1 (23.03 vs. 17.72 mm(2); P = 0.004), 3 (22.59 vs. 17.69 mm(2); P < 0.0001), and 5 cm (22.05 vs. 17.25 mm(2); P = 0.0005) proximal to the medial malleolus was significantly larger. Although the area under the curve (AUC) for CSA measurements at all three anatomical levels was similar, the CSA measured at 3 cm above the medial malleolus had an optimal threshold value for identification of DSP (19.01 mm(2)) with a sensitivity of 0.69 and a specificity of 0.77 by AUC analysis.

This large study of diabetic patients confirms that the CSA of the PTN is larger in patients with DSP than in control subjects, and US is a promising point-of-care screening tool for DSP.