Entrapment neuropathies of the tibial (posterior tibial) nerve

Morphometric assessment of tibial nerve and its branches around the ankle

It is essential to understand the considerable variations in bifurcation patterns of the tibial nerve (TN) and its peripheral nerves at the level of the tarsal tunnel to prevent iatrogenic nerve injury during surgical nerve release or nerve block. A total of 16 ankles of 8 human cadavers were dissected to investigate the branching patterns of the TN, using 2 imaginary lines passing through the tip of the medial malleolus (MM) as reference lines. Bifurcation patterns and detailed information on the relative locations of the medial plantar, lateral plantar, medial calcaneal, and inferior calcaneal nerves to the reference lines were recorded. The most common bifurcation pattern was Type 1 in 12 ankles (75%), followed by Type 2 in 2 ankles (13%). One medial calcaneal nerve (MCN) was seen in 11 (69%) specimens and 2 MCN branches were seen in 5 (31%) specimen. 88% of the MCN branches bifurcated from the TN, whereas 6% originated from both TN and lateral plantar nerve (LPN). At the level of the tip of the MM, 2 of 7 parameters showed statistically significant difference between both sexes (P < .05). There was a statistically significant difference between left and right ankles in 2 of 7 measurements (P < .05). Further morphometric analysis of the width, distance, and angle between the TN branches and the tip of MM showed a highly variable nature of the location of the peripheral nerve branches.

The role of ultrasound-guided perineural injection of the tibial nerve with a sub-anesthetic dosage of lidocaine for the diagnosis of tarsal tunnel syndrome

Background

Tarsal tunnel syndrome (TTS) involves entrapment of the tibial nerve at the medial ankle beneath the flexor retinaculum and its branches, the medial and lateral plantar nerves, as they course through the porta pedis formed by the deep fascia of the abductor hallucis muscle. TTS is likely underdiagnosed, because diagnosis is based on clinical evaluation and history of present illness. The ultrasound-guided lidocaine infiltration test (USLIT) is a simple approach that may aid in the diagnosis of TTS and predict the response to neurolysis of the tibial nerve and its branches. Traditional electrophysiological testing cannot confirm the diagnosis and only adds to other findings.

Methods

We performed a prospective study of 61 patients (23 men and 38 women) with a mean age of 51 (29-78) years who were diagnosed with idiopathic TTS using the ultrasound guided near-nerve needle sensory technique (USG-NNNS). Patients subsequently underwent USLIT of the tibial nerve to assess the effect on pain reduction and neurophysiological changes.

Results

USLIT led to an improvement in symptoms and nerve conduction velocity. The objective improvement in nerve conduction velocity can be used to document the pre-operative functional capacity of the nerve. USLIT may also be used as a possible quantitative indicator of whether the nerve has the potential to improve in neurophysiological terms and ultimately inform prognosis after surgical decompression.

Conclusion

USLIT is a simple technique with potential predictive value that can help the clinician to confirm the diagnosis of TTS before surgical decompression.

An update on imaging of tarsal tunnel syndrome

Tarsal tunnel syndrome (TTS) is an entrapment neuropathy of the tibial nerve (TN) within the tarsal tunnel (TT) at the level of the tibio-talar and/or talo-calcaneal joints. Making a diagnosis of TTS can be challenging, especially when symptoms overlap with other conditions and electrophysiological studies lack specificity. Imaging, in particular MRI, can help identify causative factors in individuals with suspected TTS and help aid surgical management. In this article, we review the anatomy of the TT, the diagnosis of TTS, aetiological factors implicated in TTS and imaging findings, with an emphasis on MRI.

An Update on Posterior Tarsal Tunnel Syndrome

Posterior tarsal tunnel syndrome (PTTS) is an entrapment neuropathy due to compression of the tibial nerve or one of its terminal branches within the tarsal tunnel in the medial ankle. The tarsal tunnel is formed by the flexor retinaculum, while the floor is composed of the distal tibia, talus, and calcaneal bones. The tarsal tunnel contains a number of significant structures, including the tendons of 3 muscles as well as the posterior tibial artery, vein, and nerve. Focal compressive neuropathy of PTTS can originate from anything that physically restricts the volume of the tarsal tunnel. The variety of etiologies includes distinct movements of the foot, trauma, vascular disorders, soft tissue inflammation, diabetes mellitus, compression lesions, bony lesions, masses, lower extremity edema, and postoperative injury. Generally, compression of the posterior tibial nerve results in clinical findings consisting of numbness, burning, and painful paresthesia in the heel, medial ankle, and plantar surface of the foot. Diagnosis of PTTS can be made with the presence of a positive Tinel sign in combination with the physical symptoms of pain and numbness along the plantar and medial surfaces of the foot. Initially, patients are treated conservatively unless there are signs of muscle atrophy or motor nerve involvement. Conservative treatment includes activity modification, heat, cryotherapy, non-steroidal anti-inflammatory drugs, corticosteroid injections, opioids, GABA analog medications, tricyclic antidepressants, vitamin B-complex supplements, physical therapy, and custom orthotics. If PTTS is recalcitrant to conservative treatment, standard open surgical decompression of the flexor retinaculum is indicated. In recent years, a number of alternative minimally invasive treatment options have been investigated, but these studies have small sample sizes or were conducted on cadaveric models.

Tarsal tunnel syndrome: current rationale, indications and results

Tarsal tunnel syndrome (TTS) is a neuropathy due to compression of the posterior tibial nerve and its branches. It is usually underdiagnosed and its aetiology is very diverse. In 20% of cases it is idiopathic. There is no test that diagnoses it with certainty. The diagnosis is usually made by correlating clinical history, imaging tests, nerve conduction studies (NCSs) and electromyography (EMG). A differential diagnosis should be made with plantar fasciitis, lumbosacral radiculopathy (especially S1 radiculopathy), rheumatologic diseases, metatarsal stress fractures and Morton’s neuroma. Conservative management usually gives good results. It includes activity modification, administration of pain relief drugs, physical and rehabilitation medicine, and corticosteroid injections into the tarsal tunnel (to reduce oedema). Abnormally slow nerve conduction through the posterior tibial nerve usually predicts failure of conservative treatment. Indications for surgical treatment are failure of conservative treatment and clear identification of the cause of the entrapment. In these circumstances, the results are usually satisfactory. Surgical success rates vary from 44% to 96%. Surgical treatment involves releasing the flexor retinaculum from its proximal attachment near the medial malleolus down to the sustentaculum tali. Ultrasound-guided tarsal tunnel release is possible. A positive Tinel’s sign before surgery is a strong predictor of surgical relief after decompression. Surgical treatment achieves the best results in young patients, those with a clear aetiology, a positive Tinel’s sign prior to surgery, a short history of symptoms, an early diagnosis and no previous ankle pathology.

Cite this article: EFORT Open Rev 2021;6:1140-1147. DOI: 10.1302/2058-5241.6.210031

Electrodiagnostic Assessment of Uncommon Mononeuropathies

Carpal tunnel syndrome, ulnar neuropathy at the elbow, and peroneal neuropathy are the most common mononeuropathies; however, other individual nerves may also be injured by various processes. These uncommon mononeuropathies may be less readily diagnosed owing to unfamiliarity with the presentations and vague symptoms. Electrodiagnostic studies are essential in the evaluation of uncommon mononeuropathies and can assist in localization and prognostication. However, they can also be challenging; stimulation at the proximal sites is difficult and well-validated reference values are not available. This article reviews the electrodiagnostic assessment of several uncommon upper and lower extremities mononeuropathies.

Can the axial cross-sectional area of the tibial nerve be used to diagnose tarsal tunnel syndrome? An ultrasonography study

INTRODUCTION

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.

HYPOTHESIS

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

METHODS

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.

RESULTS

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.

DISCUSSION

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.

LEVEL OF EVIDENCE

III, diagnostic case-control study.

Tarsal Tunnel Syndrome

Tarsal tunnel syndrome is paresthesia and pain in the foot and ankle caused by entrapment and compression of the tibial nerve within the fibro-osseous tarsal tunnel beneath the flexor retinaculum. The most helpful diagnostic criteria are a positive Tinel sign at the ankle and objective sensory loss along the distribution of the tibial nerve. Treatment is designed to reduce the compression of the nerve, and surgical nerve release is indicated with failure of conservative options. It is important to identify the causative factor of the nerve compression and eliminate it to obtain excellent results.

Ultrasound-Guided Proximal and Distal Tarsal Decompression: An Analysis of Pressures in the Tarsal, Medial Plantar, and Lateral Plantar Tunnels

Objectives. To analyze the reliability of measurements of tarsal tunnel and medial and lateral plantar tunnel pressures before and after ultrasound-guided release. Measurements taken were guided by ultrasound to improve reliability. This novel approach may help surgeons make surgical decisions. The second objective was to confirm that decompression using ultrasound-guided surgery as previously described by the authors is technically effective, reducing pressure to the tarsal and medial and lateral plantar tunnels. Methods. The study included 23 patients with symptoms compatible with idiopathic tarsal tunnel syndrome (TTS). The first step was to measure intracompartmental pressure of the tarsal tunnel, medial plantar tunnel, and lateral plantar tunnel preoperatively. The second step was ultrasound-guided decompression of the tibial nerve and its branches. Subsequently, pressure was measured again immediately after decompression in the 3 tunnels. Results. After surgery, the mean values significantly dropped to normal values. This represents a validation of effective decompression of the tibial nerve and its branches in TTS with ultra-minimally invasive surgery. Conclusions. The ultrasound-guided surgical technique to release the tibial nerve and its branches is effective, significantly reducing pressure in the tunnels and, thereby, decompressing the nerves.Level of evidence: Level IV.

Anatomical study and branching point of neurovascular structures at the medial side of the ankle

Nerve entrapment and blood circulation impairment associated with the medial side of the ankle are not uncommon. The purpose of this study was to describe the anatomical basis of neurovascular structures of the medial ankle which comprised the number, origin, branching pattern, and branching point. Forty feet of fresh cadavers were examined by using 2 reference lines: the malleolar-calcaneal (MC) and navicular-calcaneal (NC) axes. We recorded number, origin, length of the 2 axes, the locations and widths of neurovascular structures on MC and NC axes, the branching point of neurovascular structures, and the branching pattern of neurovascular structures was recorded and was separated into 5 types. The posterior tibial nerve (PTN) bifurcated to plantar and calcaneal nerves and branched proximally to the tarsal tunnel (TT). The posterior tibial artery bifurcated to plantar and calcaneal arteries and branched inferiorly to PTN and within the TT. The calcaneal nerves and arteries had more variation of number and origin. The most common branching point of calcaneal nerves and arteries is within the TT, except the medial calcaneal nerve. It branched proximally to the TT. The anatomical knowledge from this study is important for the diagnosis and treatment of clinicians.

[Selective ultrasound-guided hydrodissection of gastrocnemius nerve branch after post-surgical entrapment: Apropos of a case]

Chronic or recalcitrant plantar fasciitis is a cause of persistent plantar pain. These cases are usually resistant to conventional treatments consisting of exercises, orthoses, shock waves and infiltrations and require a surgical approach. Proximal medial gastrocnemius release is a surgical option that provides satisfactory results, but is not free of complications, which include injuries and nerve entrapment. We report the first published case of symptomatic medial gastrocnemius branch entrapment in the post-surgical scar of a tenotomy for the treatment of recalcitrant plantar fasciitis. We propose ultrasound-guided hydrodissection with local anesthetic as a treatment with promising results.

Common peripheral nerve injuries in sport: diagnosis and management

Peripheral nerve injuries are unusual in sport but impact an athlete's safe return to play. Nerve injuries result from either acute trauma (most commonly in contact/collision sports) or from repetitive microtrauma and overuse. Diagnosis of overuse nerve injuries includes nerve localization and surrounding soft-tissue anatomy, and must account for possible causes of repetitive microtrauma, including biomechanics, equipment, training schedule, and recovery. Prognosis is related to the type of nerve injury. Management should not simply be rest and gradual return to sport but should address biomechanical and training predispositions to injury. Understanding the type of injury and the tissues involved will guide appropriate rehabilitation decisions. Recognizing acute care considerations and implementing appropriate strategies can help minimize secondary trauma to an area following acute injury.

Schwannoma and neurofibroma of the posterior tibial nerve presenting as tarsal tunnel syndrome: review of the literature with two case reports

We present two case reports of peripheral nerve tumors (schwannoma and neurofibroma) that presented as tarsal tunnel syndrome for many years. There has never been a report of multiple neurofibroma of the posterior tibial nerve presenting as a tarsal tunnel syndrome. Both patients were treated surgically with good outcomes.

Diagnostic utility of distal nerve conduction studies and sural near-nerve needle recording in polyneuropathy

OBJECTIVE

The electrodiagnosis of polyneuropathy (PNP) may benefit from examination using near-nerve needle technique (NNT) and from inclusion of distal nerves. This study compared the diagnostic utility of distal nerve conduction studies (NCS) and NNT recording.

METHODS

Bilateral NNT and surface recording of the sural nerve and surface recording of the dorsal sural and medial plantar nerves were prospectively done in 91 patients with clinically suspected PNP. Distal NCS were additionally done in 37 healthy controls. Diagnostic reference standard was the final clinical diagnosis retrieved from the patients medical records after 1-4years.

RESULTS

The clinical follow-up diagnosis confirmed PNP in 68 patients. Equally high sensitivities of the dorsal sural (72%), medial plantar (75%), and sural nerve with NNT recording (77%) were seen, while the sensitivity of conventional surface recording of the sural nerve was lower (60%). Sural NCS with both NNT and surface recording and dorsal sural NCS showed high specificities (85-95%) and positive predictive values (94-98%), while a lower specificity was seen for the medial plantar nerve (68%).

CONCLUSION

NCS of distal nerves, especially the dorsal sural nerve, have high diagnostic power equalling sural NNT recording.

SIGNIFICANCE

The electrodiagnostic evaluation of patients with suspected PNP benefits from NCS of distal nerves.

Nerve ultrasound in electrophysiologically verified tarsal tunnel syndrome

INTRODUCTION

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.

METHODS

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

RESULTS

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.

CONCLUSIONS

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.

Tarsal tunnel syndrome-A narrative literature review

BACKGROUND

Tarsal tunnel syndrome is classified as a focal compressive neuropathy of the posterior tibial nerve or one of its associated branches individually or collectively. The tunnel courses deep to fascia, the flexor retinaculum and within the abductor hallucis muscle of the foot/ankle. The condition is rare and regularly under-diagnosed leading to a range of symptoms affecting the plantar margins of the foot. There are many intervention strategies for treating tarsal tunnel syndrome with limited robust evidence to guide the clinical management of this condition. The role of conservative versus surgical interventions at various stages of the disease process remains unclear, and there is a need for a structured, step-wise approach in treating patients with this syndrome based on derived empirical evidence. This narrative review attempts to scrutinize the literature to date by clarifying initial presentation, investigations and definitive treatment for the purpose of assisting future informed clinical decision and prospective research endeavours.

PROCESS

The literature searches that have been incorporated in compiling a rigorous review of this condition have included: the Cochrane Neuromuscular Group's Specialized Register (Cochrane Library 2013), the databases of EMBASE, AMED, MEDLINE, CINAHL, Physiotherapy evidence database (PEDRO), Biomed Central, Science Direct and Trip Database (1972 to the present). Reference listings of located articles were also searched and scrutinized. Authors and experts within the field of lower-limb orthopaedics were contacted to discuss applicable data. Subject-specific criteria searches utilizing the following key terms were performed across all databases: tarsal tunnel syndrome, tibial neuralgia, compression neuropathy syndromes, tibial nerve impingement, tarsal tunnel neuropathy, entrapment tibial nerve, posterior tibial neuropathy. These search strategies were modified with differing databases, adopting specific sensitivity-searching tools and functions unique to each. This search strategy identified 88 journal articles of relevance for this narrative literature review.

FINDINGS

This literature review has appraised the clinical significance of tarsal tunnel syndrome, whilst assessing varied management interventions (non-surgical and surgical) for the treatment of this condition in both adults and children. According to our review, there is limited high-level robust evidence to guide and refine the clinical management of tarsal tunnel syndrome. Requirements for small-scaled randomized controlled trials in groups with homogenous aetiology are needed to analyse the effectiveness of specific treatment modalities.

CONCLUSIONS

It is necessary that further research endeavours be pursued for the clinical understanding, assessment and treatment of tarsal tunnel syndrome. Accordingly, a structured approach to managing patients who have been correctly diagnosed with this condition should be formulated on the basis of empirical evidence where possible.

Posterior tibial vein aneurysm presenting as tarsal tunnel syndrome

Tarsal tunnel syndrome is a compressive neuropathy of the posterior tibial nerve within the tarsal tunnel. Its etiology varies, including space occupying lesions, trauma, inflammation, anatomic deformity, iatrogenic injury, and idiopathic and systemic causes. Herein, we describe a 46-year-old man who presented with left foot pain. Work up revealed a venous aneurysm impinging on the posterior tibial nerve. Following resection of the aneurysm and lysis of the nerve, his symptoms were alleviated. Review of the literature reveals an association between venous disease and tarsal tunnel syndrome; however, this report represents the first case of venous aneurysm causing symptomatic compression of the nerve.

Neurolysis for failed tarsal tunnel surgery

The purpose of the present study was to investigate the causes of failure after tarsal tunnel release and the operative findings in the secondary interventions and the outcomes. The data from 8 patients who had undergone revision surgery for failed tarsal tunnel release at least 12 months earlier were evaluated retrospectively. Only the patients with idiopathic tarsal tunnel syndrome were included, and all had unilateral symptoms. Neurophysiologic tests confirmed the clinical diagnosis of failed tarsal tunnel release in all patients. Magnetic resonance imaging revealed varicose veins within the tarsal tunnel in 1 patient (12.5%) and tenosynovitis in another (12.5%). Open tarsal tunnel release was performed in all patients, and the tibialis posterior nerve, medial and lateral plantar nerves (including the first branch of the lateral plantar nerve), and medial calcaneal nerve were released in their respective tunnels, and the septum between the tunnels was resected. The outcomes were assessed according to subjective patient satisfaction as excellent, good, fair, or poor. During revision surgery, insufficient release of the tarsal tunnel, especially distally, was observed in all the patients, and fibrosis of the tibialis posterior nerve was present in 1 (12.5%). The outcomes according to subjective patient satisfaction were excellent in 5 (62.5%), good in 2 (25%), and fair in 1 (12.5%). The fair outcome was obtained in the patient with fibrosis of the nerve. Insufficient release of the tarsal tunnel was the main cause of failed tarsal tunnel release. Releasing the 4 distinct tunnels and permitting immediate mobilization provided satisfactory results in patients with failed tarsal tunnel release.

Compression and entrapment neuropathies

Peripheral nerve entrapments are frequent. They usually appear in anatomical tunnels such as the carpal tunnel. Nerve compressions may be due to external pressure such as the fibular nerve at the fibular head. Malignant or benign tumors may also damage the nerve. For each nerve from the upper and lower limbs, detailed clinical, electrophysiological, imaging, and therapeutic aspects are described. In the upper limbs, carpal tunnel syndrome and ulnar neuropathy at the elbow are the most frequent manifestations; the radial nerve is less frequently involved. Other nerves may occasionally be damaged and these are described also. In the lower limbs, the fibular nerve is most frequently involved, usually at the fibular head by external compression. Other nerves may also be involved and are therefore described. The clinical and electrophysiological examination are very important for the diagnosis, but imaging is also of great use. Treatments available for each nerve disease are discussed.

Potential sites of compression of tibial nerve branches in foot: a cadaveric and imaging study

Hypertrophy of abductor hallucis muscle is one of the reported causes of compression of tibial nerve branches in foot, resulting in tarsal tunnel syndrome. In this study, we dissected the foot (including the sole) of 120 lower limbs in 60 human cadavers (45 males and 15 females), aged between 45 and 70 years to analyze the possible impact of abductor hallucis muscle in compression neuropathy of tibial nerve branches. We identified five areas in foot, where tibial nerve branches could be compressed by abductor hallucis. Our findings regarding three of these areas were substantiated by clinical evidence from ultrasonography of ankle and sole region, conducted in the affected foot of 120 patients (82 males and 38 females), aged between 42 and 75 years, who were referred for evaluation of pain and/or swelling in medial side of ankle joint with or without associated heel and/or sole pain. We also assessed whether estimation of parameters for the muscle size could identify patients at risk of having nerve compression due to abductor hallucis muscle hypertrophy. The interclass correlation coefficient for dorso-planter thickness of abductor hallucis muscle was 0.84 (95% CI, 0.63-0.92) and that of medio-lateral width was 0.78 (95% CI, 0.62-0.88) in the imaging study, suggesting both are reliable parameters of the muscle size. Receiver operating characteristic curve analysis showed, if ultrasonographic estimation of dorso-plantar thickness is >12.8 mm and medio-lateral width > 30.66 mm in patients with symptoms of nerve compression in foot, abductor hallucis muscle hypertrophy associated compression neuropathy may be suspected.

3T magnetic resonance neurography of tibial nerve pathologies

Diagnosis of tibial neuropathy has been traditionally based on clinical examination and electrodiagnostic studies; however, cross-sectional imaging modalities have been used to increase the diagnostic accuracy and provide anatomic mapping of the abnormalities. In this context, magnetic resonance neurography (MRN) offers high-resolution imaging of the tibial nerve (TN), its branches and the adjacent soft tissues, and provides an objective assessment of the neuromuscular anatomy, abnormality, and the surrounding pathology. This review describes the pathologies affecting the TN and illustrates their respective 3 Tesla (T) MRN appearances with relevant case examples.

High resolution imaging of tunnels by magnetic resonance neurography

Peripheral nerves often traverse confined fibro-osseous and fibro-muscular tunnels in the extremities, where they are particularly vulnerable to entrapment and compressive neuropathy. This gives rise to various tunnel syndromes, characterized by distinct patterns of muscular weakness and sensory deficits. This article focuses on several upper and lower extremity tunnels, in which direct visualization of the normal and abnormal nerve in question is possible with high resolution 3T MR neurography (MRN). MRN can also serve as a useful adjunct to clinical and electrophysiologic exams by discriminating adhesive lesions (perineural scar) from compressive lesions (such as tumor, ganglion, hypertrophic callous, or anomalous muscles) responsible for symptoms, thereby guiding appropriate treatment.

MR imaging mapping of skeletal muscle denervation in entrapment and compressive neuropathies

The diagnoses of entrapment and compressive neuropathies have been based on the findings from clinical examinations and electrophysiologic tests, such as electromyography and nerve conduction studies. The use of magnetic resonance (MR) imaging for the diagnosis of entrapment or compressive neuropathies is increasing because MR imaging is particularly useful for discerning potential causes and for identifying associated muscle denervation. However, it is sometimes difficult to localize nerve entrapment or demonstrate nerve compression lesions with MR imaging. Nevertheless, even in these cases, MR imaging may show denervation-associated changes in specific muscles innervated by the affected nerves. The analysis of denervated muscle distributions by using MR imaging, with a knowledge of nerve innervation patterns, would be helpful for determining the nerves involved and the levels of nerve entrapment or compression. In this context, the mapping of skeletal muscle denervation with MR imaging has a supplementary or even a primary role in the diagnosis of entrapment and compressive neuropathies.

Clinical utility of tibial motor and sensory nerve conduction studies with motor recording from the flexor hallucis brevis: a methodological and reliability study

Background

Standard tibial motor nerve conduction measures are established with recording from the abductor hallucis. This technique is often technically challenging and clinicians have difficulty interpreting the information particularly in the short segment needed to assess focal tibial nerve entrapment at the medial ankle as occurs in posterior tarsal tunnel syndrome. The flexor hallucis brevis (FHB) has been described as an alternative site for recording tibial nerve function in those with posterior tarsal tunnel syndrome. Normative data has not been established for this technique. This pilot study describes the technique in detail. In addition we provide reference values for medial and lateral plantar orthodromic sensory measures and assessed intrarater reliability for all measures.

Methods

Eighty healthy female participants took part, and 39 returned for serial testing at 4 time points. Mean values ± SD were recorded for nerve conduction measures, and coefficient of variation as well as intraclass correlation coefficients (ICC) were calculated.

Results

Motor latency, amplitude and velocity values for the FHB were 4.1 ± 0.9 msec, 8.0 ± 3.0 mV and 45.6 ± 3.4 m/s, respectively. Sensory latencies, amplitudes, and velocities, respectively, were 2.8 ± 0.3 msec, 26.7 ± 10.1 μV, and 41.4 ± 3.5 m/s for the medial plantar nerve and 3.2 ± 0.5 msec, 13.3 ± 4.7 μV, and 44.3 ± 4.0 msec for the lateral plantar nerve. All values demonstrated significant ICC values (P ≤ 0.007).

Conclusion

Motor recording from the FHB provides technically clear waveforms that allow for an improved ability to assess tibial nerve function in the short segments used to assess tarsal tunnel syndrome. The reported means will begin to establish normal values for this technique.

The diagnosis and treatment of heel pain: a clinical practice guideline-revision 2010

Heel pain, whether plantar or posterior, is predominantly a mechanical pathology although an array of diverse pathologies including neurologic, arthritic, traumatic, neoplastic, infectious, or vascular etiologies must be considered. This clinical practice guideline (CPG) is a revision of the original 2001 document developed by the American College of Foot and Ankle Surgeons (ACFAS) heel pain committee.

Segmental analysis of motor conduction velocity in distal tracts of tibial nerve: a coaxial needle electrode study

OBJECTIVE

To describe a new method of segmental analysis of motor nerve conduction velocity (mCV) in the tibial nerve (Tn) tract distal to the upper margin of the tarsal tunnel (TT).

METHODS

Compound muscle action potentials (CMAPs) were recorded with a coaxial needle electrode from the flexor hallucis brevis muscle (FHB), to test the medial plantar nerve (MPn), and from the flexor digiti quinti brevis (FDQB) and the first dorsal interosseous (FDI) muscles, to test the superficial and deep branches of the lateral plantar nerve (sLPn and dLPn, respectively). CMAPs were elicited by stimulating at three sites located above (S1) and below (S2) the TT and at the sole of the foot (S3 for MPn and S4 for LPn).

RESULTS

In 20 normal subjects the mean mCV in the proximal (S1 to S2) tract was 44.5+/-4.7, 43.5+/-5.9 and 42.6+/-4.2m/s for the MPn, sLPn and dLPn, respectively. The corresponding values in the intermediate tract (S1 to S3/S4) were 40.7+/-5.6, 39.4+/-5.6 and 40.9+/-5.8m/s.

CONCLUSIONS

Segmental analysis of mCV in distal Tn can be performed when CMAPs are recorded using a coaxial needle electrode, which prevents simultaneous recording of activity from nearby muscles groups.

SIGNIFICANCE

Conventional neurophysiological examination for suspected entrapments in distal Tn usually can not discriminate between a lesion inside the TT or distal to it. The proposed technique, as suggested by the reported results in clinical application, may help to better define the lesion site.

Reliability and size of the measurement error when determining the cross-sectional area of the tibial nerve at the tarsal tunnel with ultrasonography

An in depth analysis of the reliability of ultrasonography to measure the cross-sectional area of the tibial nerve or any other peripheral nerve is not available in the literature. This study determined the reliability and size of the measurement error of high-resolution ultrasound to measure the size of the tibial nerve at the tarsal tunnel. The cross-sectional area of the tibial nerve was measured by two experienced sonographers at 1 cm proximal to the medial malleolus. Measurements were made in 10 healthy participants without plantar heel pain. Intra and intertester reliability were determined by calculation of intraclass correlation coefficients (ICC), measurement error magnitude and smallest detectable difference (SDD). A direct (tracing) and indirect (ellipsoid formula) method were evaluated. Results demonstrated that the intra and intertester reliability were excellent (ICC, all > or =0.86). The measurement error and SDD were very small, especially when measurements from three scans were averaged (measurement error: 0.4-0.9 mm2; SDD: 1.1-2.5 mm2). The findings of this study support the view that high-resolution ultrasound is reliable to measure the cross-sectional area of a peripheral nerve. As a result of the small measurement error, a side-to-side difference as small as approximately 1.8 mm2 can be interpreted meaningfully in an individual patient. This difference is much smaller than the swelling reported in the literature for patients with tibial neuropathy.

Posterior tarsal tunnel syndrome: diagnosis and treatment

BACKGROUND

Posterior tarsal tunnel syndrome is an uncommon clinical entity which is sometimes misdiagnosed in patients with pain of the retromalleolar region and the plantar aspect of the foot. Surgical intervention is recommended for correctly diagnosed posterior tarsal tunnel syndrome.

METHODS

Selective literature review.

RESULTS

Surgical treatment is indicated in the presence of dysesthesias refractory to conservative treatment or of neurological deficits. If a neural tumor or tarsal tunnel ganglion is suspected, diagnostic imaging (MRI, neurosonography) should precede surgery. Division of the flexor retinaculum (ligamentum laciniatum) in the tarsal tunnel must always include distal decompression of the end branches of the tibial nerve posterior to the fascia of the abductor hallucis muscle. Only extensive exposure of the nerve guarantees adequate release.

CONCLUSION

Accurate diagnosis requires the evaluation of relevant clinical, neurological, and neurophysiological findings along with the careful consideration of other possible diagnoses. High success rates of 44% to 91% are reported after operative treatment. The results are better in idiopathic than in posttraumatic cases. If surgery fails, re-operation is indicated only in patients with inadequate release.

Abnormal dip phenomenon: a characteristic electrophysiological marker in interdigital neuropathy of the foot

OBJECTIVE: The nerve conduction findings in interdigital neuropathy of the foot (IDN; Morton's neuroma) have rarely been reported. We analyzed the nerve conduction data in 23 patients with suspected IDN studied between 1982 and 2002. METHOD: Diagnosis of IDN was made on the basis of clinical features. All patients underwent routine nerve conduction studies and a near-nerve needle sensory nerve conduction study of the interdigital nerves by Oh's method in the symptomatic foot. RESULTS:Of the 23 patients, the diagnosis of definite IDN was made in 13 cases and of possible NDN in the others cases. Nineteen were females. Twenty two patients had only one nerve affected. One patient had two nerves affected. The III-IV interdigital nerve was affected in 17 cases and the II-III interdigital nerve in 7 cases. The near-nerve needle nerve conduction showed abnormality in the affected interdigital nerves in all definite IDN cases and confirmed the diagnosis of IDN in 10 cases by the abnormal dip phenomenon (a selective decrease of 50% or more in the sensory CNAP amplitude of the affected nerve compared with that of the preceding interdigital nerve). In 11 possible IDN cases, IDN was identified by the abnormal dip phenomenon. CONCLUSION: The near-nerve needle sensory nerve conduction of the interdigital nerves is a highly sensitive diagnostic test, and abnormal dip phenomenon is the most characteristic electrophysiological marker for the diagnosis of IDN.

Tarsal tunnel decompression in leg lengthening and deformity correction of the foot and ankle

Decompression of the tarsal tunnel has been performed since the 1960s and has resulted in variable outcomes. The success rate of this procedure has ranged from 44% to 95%. We review the anatomy of the tarsal tunnel region and offer a detailed surgical approach for the decompression of its contents. We also discuss the role of this procedure in leg lengthening and deformity correction of the foot and ankle.

Ultrasonography of the tibial nerve in vasculitic neuropathy

Ultrasonography is a new imaging method for visualizing peripheral nerves. In vasculitic neuropathy, pain or axonopathy often can prevent the lesion from being localized during electrophysiological examinations, but the ability of ultrasonography to evaluate it morphologically is unknown. Our aim was to determine whether ultrasonography could be used to detect abnormalities in tibial vasculitic neuropathy at the medial ankle. We evaluated 11 tibial nerves in 8 patients with tibial vasculitic neuropathy, and 35 tibial nerves in 35 control subjects. In the controls, the tibial nerve was successfully visualized as a hyperechoic nodule with multiple round hypoechoic areas transversely; in the patients, the tibial nerve appeared enlarged and hypoechoic. The affected nerve area was significantly larger (13.5 +/- 3.7 mm(2)) than in controls (7.2 +/- 1.5 mm(2)). Our results suggest that ultrasonography is a useful neuroimaging method for evaluation of tibial vasculitic neuropathy, especially when nerve conduction study findings are inconclusive.

Concepts in pain management

Pain has become an increasingly recognized symptom that plays a major role in the treatment of many podiatric patients. Management of this now accepted fifth vital sign can be accomplished through many avenues. Nonsteroidal anti-inflammatory medications and short- and long-acting opioids are typically used by many podiatric physicians; however, the benefits and potential hazards of other pharmaceutic approaches using antidepressants, anticonvulsants, topical medications, and other centrally acting medications must also be recognized. In addition, the role of the psychiatrist or therapist should not be neglected because many types of cognitive therapies are available to aid in treating these patients.

Neuropathies of the foot

Compared with the common neuropathies affecting the hands (carpal tunnel syndrome and ulnar neuropathy), neuropathies of the feet have received less attention in the past. This is partly because of the rarity of these disorders as well as the lack of reliable electrophysiological tests for them. Over the years, nerve conduction tests for various nerves of the feet have been reported, and at this time techniques for all the nerves of the feet are available to the electromyographer. This review will provide up-to-date information on the current status of the research and issues relating to the neuropathies of the foot, with an emphasis on the most useful tests and the caveats for clinical neurophysiologists.

Role of magnetic resonance imaging in entrapment and compressive neuropathy—what, where, and how to see the peripheral nerves on the musculoskeletal magnetic resonance image: part 1. Overview and lower extremity

The diagnosis of nerve entrapment and compressive neuropathy has been traditionally based on the clinical and electrodiagnostic examinations. As a result of improvements in the magnetic resonance (MR) imaging modality, it plays not only a fundamental role in the detection of space-occupying lesions but also a compensatory role in clinically and electrodiagnostically inconclusive cases. Although ultrasound has undergone further development in the past decades and shows high resolution capabilities, it has inherent limitations due to its operator dependency. We review the general concepts that should be known to evaluate the entrapment and compressive neuropathy in MR imaging. We also review the course of normal peripheral nerves, as well as various clinical demonstrations and pathological features of compressed and entrapped nerves in the lower extremities on MR imaging, according to the nerves involved. The common sites of nerve entrapment of the lower extremity are as follows: sciatic nerve around the piriformis muscle; tibial nerve at the popliteal fossa and tarsal tunnel, common peroneal nerve around the fibular neck, and digital nerve near the metatarsal head. Although MR imaging can depict the peripheral nerves in the extremities effectively, radiologists should be familiar with nerve pathways, common sites of nerve compression, and common space-occupying lesions resulting in nerve compression in MR imaging.

Liberação do túnel do tarso pela técnica endoscópica: uma proposta de acesso cirúrgico

Estabelecer em cadáveres, dois portais, através da delimitação de pontos anatômicos e linhas geométricas, que permitam o acesso ao Túnel do Tarso pela técnica videoendoscópica e comparar a abordagem no sentido proximal para distal com a reversa. Fizeram parte do estudo 18 cadáveres, com um total de 36 tornozelos. Partindo da técnica endoscópica bi-portal inicialmente descrita, e modificada neste estudo através da padronização de pontos anatômicos e linhas geométricas, o Túnel do Tarso foi liberado nos tornozelos esquerdos com a inserção do instrumental no sentido proximal para distal e o inverso nos direitos.Nos tornozelos direitos, houve secção completa do retináculo flexor em 15 casos (83,3%) e parcial em 3 casos (16,67%). Nos esquerdos, a secção foi completa em 16 casos (88,89%) e parcial em 2 casos (11,11%). O tempo operatório no lado direito foi em média 19,44 minutos e no esquerdo 18,33 minutos. Em nenhum caso foi observada lesão de estruturas neurovasculares. Com a técnica proposta a secção total do retináculo dos flexores foi obtida em todos os casos após a curva do aprendizado, sem lesão de estruturas anatômicas do túnel do Tarso, independente do sentido utilizado na via de acesso.

Neurogenic heel pain

This article establishes a standard approach for the evaluation of patients with heel pain. With this approach, it should become easier for the physician to distinguish between neurogenic and inflammatory heel pain and to devise a more direct plan for definitive treatment.

Soft-tissue injuries of the lower extremity

A diverse set of conditions affect the lower extremities in athletes. Good history taking and knowledge of the anatomy of the affected areas can aid in accurate diagnosis. Most conditions can be treated conservatively with great success. Familiarity with rehabilitation strategies can assist physicians in working with physical therapists. New advances, especially in the therapy of plantar fasciitis, may aid physicians in more rapid treatment of conditions of overuse. Surgery can provide definitive relief from symptoms for athletes with whom conservative measures have failed.

An electrophysiological severity scale in tarsal tunnel syndrome

OBJECTIVE

To propose a neurophysiological classification of tarsal tunnel syndrome.

MATERIAL AND METHODS

We retrospectively reviewed the medical records of two electromyography laboratories. Case inclusion criteria were based on clinical parameters. Motor conduction velocity, distal motor latency (DML), sensory conduction velocity (SCV) and sensory action potential (SAP) from big toe (T1) and from fifth toe (T5) to medial malleolus were measured in the medial and plantar nerves. When SCVs of T1 and T5 were normal, we considered the difference in T1 SCV between affected and unaffected side and in T1 SCV of the affected side with sural nerve distal SCV. Feet with TTS were classified in six electrophysiological classes: 0, normal SCV and DML; 1, normal absolute SCV with abnormal comparative tests; 2, slowing of T1 and T5 SCV and normal DML; 3, slowing of SCV and DML; 4, absence of T1 and T5 SAPs and abnormal DML; 5, absence of sensory and motor response.

RESULTS

A total of 111 feet belonging to 96 patients (27 men, 69 women; mean age 49.6 years) were diagnosed with TTS. T1 and T5 SCV were abnormal in 82 and 73% of cases, respectively, and comparative tests were abnormal in a further 7% of cases. DML was abnormal in 82 feet (73.9%). Eight feet (7%) were without neurographic abnormalities. The distribution of feet in neurophysiological classes was: stage 0, 7%; stage 1, 9%; stage 2, 10%; stage 3, 39%; stage 4, 32%; stage 5, 3%. Higher clinical scores coincided with higher neurographic classes.

CONCLUSION

The progression of neurographic abnormalities in TTS reflects the relation between SCV and DML, and between neurographic values and clinical severity. The scale assigns severity classes in a reliable and non-arbitrary way. This classification can easily be used by electrophysiological laboratories with their own electrophysiological techniques and normal values.

Surgical management and results of 135 tibial nerve lesions at the Louisiana State University Health Sciences Center

OBJECTIVE

This retrospective study presents 33 years of clinical and surgical experience with 135 tibial nerve lesions to review operative techniques and their results and to provide management guidelines for the proper selection of surgical candidates.

METHODS

Between 1967 and 1999, 135 patients with tibial nerve lesions at the knee level or below were managed surgically at the Louisiana State University Health Sciences Center. We reviewed these cases.

RESULTS

Of the 135 cases, traumatic injury accounted for 71, tarsal tunnel syndrome for 46, and nerve sheath tumor for 18. Of 22 lesions not in continuity, functional recovery of Grade 3 or better was achieved in 4 (67%) of 6 patients who required end-to-end suture repair and 11 (69%) of 16 patients who required graft repair. One hundred thirteen tibial nerve lesions in continuity underwent primarily external or internal neurolysis or resection of the lesions. A few received end-to-end suture or graft repair. Direct intraoperative recording of nerve action potentials guided case management decisions. Among the 113 patients with lesions in continuity, 76 (81%) of 94 patients receiving neurolysis, 5 (83%) of 6 receiving suture repair, and 11 (85%) of 13 receiving graft repair recovered function to Grade 3 or better. Repair results were best in patients with recordable nerve action potentials treated by external neurolysis. Results were poor in a few patients with very lengthy lesions in continuity and in reoperated patients with tarsal tunnel syndrome.

CONCLUSION

Surgical exploration and repair of tibial nerve lesions, including nerve sheath tumors and tarsal tunnel syndromes, achieved excellent outcomes.

Electrophysiologic response recorded in the first dorsal interosseous muscle with stimulation of the tibial and deep fibular nerves

Foot intrinsic muscle innervation may demonstrate some variability. The first dorsal interosseous muscle (FDI) is innervated by the deep branch of the lateral plantar nerve (LPN) from the main trunk of the tibial nerve. Contribution from the deep fibular nerve (DFN) may also play a role in the supply of the FDI. Thirty healthy adult volunteers were studied to determine the presence and type of response in the FDI with stimulation of the tibial nerve/deep branch of the LPN and DFN. Both nerves were stimulated at the ankle and knee with a surface and needle recording from the FDI. Latency, amplitude, and conduction values were recorded for each nerve. The incidence of DFN supply to the FDI was 16.6% with a mean ankle amplitude of 152 microV. The incidence of tibial nerve/deep branch of the LPN supply to the FDI was 100%, with a mean ankle amplitude of 5.11 mV. The superficial branch of the LPN is most often studied when evaluating for tarsal tunnel syndrome because the standard recording site is the abductor digiti minimi (ADM). Recording from the ADM, however, frequently produces a less than desirable waveform, and the technical challenges encountered with this site make tarsal tunnel syndrome assessment difficult. It is also possible that selective involvement of the deep branch of the LPN may occur, and if so, recording from the FDI may prove valuable.

Neurosensory testing of the medial calcaneal and medial plantar nerves in patients with plantar heel pain

Eighty-two patients with a chief complaint of plantar heel pain were evaluated for sensory abnormalities within the cutaneous distribution of both the medial calcaneal nerve and the medial plantar nerve, using quantitative neurosensory testing with a pressure-specified sensory device. The results showed that 22.68% of the patients displayed isolated abnormal sensory function within the distribution of the medial calcaneal nerve, whereas 49.48% of the patients displayed abnormal function within the distribution of both the medial calcaneal and the medial plantar nerves. Thus, 72.17% of the patients displayed abnormal sensory function within the distribution of the medial calcaneal nerve. Statistical analysis of the results, using the Pearson chi-square statistic and odds ratio, indicated that a significant percentage of patients with plantar heel pain, even early in the clinical course of plantar heel pain, display abnormal sensibility within the branches of the posterior tibial nerve, and specifically, within the distribution of the medial calcaneal nerve (P <.0008) and the medial plantar nerve (P <.0001).