Tibial nerve entrapment in the popliteal fossa

Canalis cruropopliteus - the overlooked canal of Wenzel Gruber

It is widely known that the popliteal fossa and the lower leg are connected by a canal, containing the neuro-vascular bundle to the posterior leg region, containing the tibial nerve and the posterior tibial artery and veins. The existence of this canal has not been duly recognized in literature, even though it has been named by Wenzel Gruber in 1871, and its contents, walls, entrance, and exits have been extensively described by him in 1878. In the present paper, we would like to pay a homage to the work of this prominent anatomist, which retains its significance for contemporary surgical practice. The cruropopliteal canal, canalis cruropopliteus, as named by him, and having been assigned a multitude of terms in practice, deserves to regain its eponymous name - Gruber's canal. The history, and the anatomy with its clinical implications are discussed herein. We hereby recommend that the original name of this canal be included in anatomical textbooks and specialized literature.

Exercise induced neuropathic lower leg pain due to a tibial bone exostosis

Objectives: The differential diagnosis of chronic exercise induced lower leg pain in sporters includes compartment syndrome and medial tibial stress syndrome. However, severe discomfort may also be caused by nerve entrapment.Methods: Here we present a marathon runner who reports pain day and night in the lower leg. Deep palpation suggested the presence of a bony tumor deep in the calf musculature, and digital pressure on the soleal sling was painful and elicited paresthesias in the foot. A swab test indicated a hypo-esthetic sole of the foot. Imaging revealed the presence of a tibial exostosis that was hypothesized to narrow the soleal tunnel and irritate the tibial nerve.Results: Via a medial infragenual approach, the soleal tunnel was opened. A bony prominence was found in direct contact to the tibial nerve. Resection of the exostosis with tibial nerve neurolysis completely abolished all of his symptoms.Conclusion: An awkward lower leg discomfort that is present at night and worsens during exercise combined with altered foot sole skin sensation in the presence of a tibial bone exostosis may suggest tibial nerve neuropathy. If conservative therapies fail, resection and neurolysis is advised.

Idiopathic Pediatric Tibial Nerve Palsy

Tibial nerve entrapment is uncommon in the pediatric population, and presents diagnostic and treatment challenges. We present the unusual case of a 3-year-old male child with progressive lower leg atrophy of an unknown etiology. Preoperative electrodiagnostic testing and magnetic resonance imaging suggested proximal tibial neuropathy. Surgical exploration showed compression of the tibial nerve at the inferior fascial edge of the long head of the biceps femoris and at the soleal sling. Release and external neurolysis led to improvement of distal leg motor function.

A 2-year follow-up survey of 523 cases with peripheral nerve injuries caused by the earthquake in Wenchuan, China

We performed a 2-year follow-up survey of 523 patients with peripheral nerve injuries caused by the earthquake in Wenchuan, Sichuan Province, China. Nerve injuries were classified into three types: type I injuries were nerve transection injuries, type II injuries were nerve compression injuries, and type III injuries displayed no direct neurological dysfunction due to trauma. In this study, 31 patients had type I injuries involving 41 nerves, 419 had type II injuries involving 823 nerves, and 73 had type III injuries involving 150 nerves. Twenty-two patients had open transection nerve injury. The restoration of peripheral nerve function after different treatments was evaluated. Surgical decompression favorably affected nerve recovery. Physiotherapy was effective for type I and type II nerve injuries, but not substantially for type III nerve injury. Pharmacotherapy had little effect on type II or type III nerve injuries. Targeted decompression surgery and physiotherapy contributed to the effective treatment of nerve transection and compression injuries. The Louisiana State University Health Sciences Center score for nerve injury severity declined with increasing duration of being trapped. In the first year after treatment, the Louisiana State University Health Sciences Center score for grades 3 to 5 nerve injury increased by 28.2% to 81.8%. If scores were still poor (0 or 1) after a 1-year period of treatment, further treatment was not effective.

Earthquake generated proximal tibial nerve compression treated by surgery

PURPOSE

This article reports on nine cases of proximal tibial nerve compression by the soleal tendinous arch caused by unsuitable treatment of acute compartment syndrome (ACS). Also, we report the clinical results of neurolysis and analyse the cause of this special type of neurological compression.

METHODS

There were nine extremities in nine patients included in the study. All patients were among the victims of the Wenchuan earthquake in 2008. All patients had a previous lower extremity ACS. Pain level, numbness in the sole, muscle strength of the flexor hallucis longus and Tinel's sign were evaluated pre- and post-operatively. Each proximal tibial nerve compression was subjected to neurolysis with division of the soleal tendinous arch.

RESULTS

At a mean follow-up of 22 months, eight patients (87 %) with weakness of the flexor hallucis longus showed improvement in flexor strength and seven patients (78 %) exhibited improved sensory function in the sole. All patients experienced pain relief. Subjective pain was reduced from an average score of 2.7 to 0.7 based on a visual analogue scale. Physical examination for Tinel's sign revealed all patients experienced relief of radiating pain, but two patients still retained a positive Tinel's sign (mild) over the soleal tendinous arch. In summary, four patients were highly satisfied, four were satisfied and one was neither satisfied nor dissatisfied with functional recovery after neurolysis.

CONCLUSIONS

Unsuitable treatment of lower extremity ACS can lead to tibial nerve compression beneath the soleal tendinous arch. Neurolysis may improve pain and sensory and motor function.

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.

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.

Sonographic evaluation of peripheral nerve injuries following the Wenchuan earthquake

PURPOSE

To analyze retrospectively the sonographic characteristics of the peripheral nerve injuries (PNIs) resulted from Wunchuan earthquake.

METHODS

The sonographic images of 38 patients with surgically proved PNIs were reviewed and compared with the surgical findings.

RESULTS

A total of 78 nerves in 38 patients were found injured in surgery, which included 16 median nerves in the forearm (20.5%), 6 ulnar nerves in the forearm or arm (7.7%), 8 radial nerves in upper limb (10.0%), 8 sciatic nerves (10.3%) in gluteal region, 17 tibial nerves in the leg (21.8%), and 23 peroneal nerves (29.5%). The most common injured nerve in the lower extremity was the peroneal nerve (29.5%) and in upper extremity was the median nerve (20.5%). Sonography correctly diagnosed 72 earthquake-related nerve injuries (92.3%), which included 5 complete disruption (6.4%), 4 partial disruption (5.1%), 63 nerve entrapment (88.5%, included 1 entrapment by bone calus, 38 entrapments by the scar tissue, 13 entrapments by the thickened muscle or tendinous arch, and 11 entrapment in the narrowed osteofibrous tunnels).

CONCLUSIONS

Nerve entrapment injury was the common sonographic finding in earthquake-related PNI.

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 neurography findings of soleal sling entrapment

OBJECTIVE

The ever-increasing use of higher field strength (3 T) scanners and novel pulse sequences with improved spatial resolution and signal-to-noise ratio have rendered MR neurography (MRN) a valuable technique in the assessment of peripheral neuropathies. The aim of this study is to illustrate the imaging findings of high-resolution MRN in patients who suffer from tibial nerve entrapment due to a soleal fibromuscular sling and to correlate the imaging findings with intraoperative and clinical examination results.

CONCLUSION

This article depicts the surgically confirmed imaging findings of high-resolution MRN in tibial nerve entrapment by the soleal sling.

Anatomic site for proximal tibial nerve compression: a cadaver study

Primary compression of the tibial nerve beneath the fibromuscular sling of the origin of the soleus muscle is rarely discussed in the literature. To evaluate the location and characteristics of the soleal fibromuscular sling and its relationship to the tibial nerve, 36 cadaver limbs were dissected. The leg length, location of soleal fibromuscular sling, presence of a thickened fibrous band at the soleal sling, and narrowing in the tibial nerve were recorded. The average leg length was 47.8 cm (SD +/- 4.16). The fibromuscular soleal sling was 9.3 cm (SD +/- 1.44) distal to the medial tibial plateau. Although 56% (20/36) of specimens had a fibrous band, only 8% (3/36) demonstrated a focal narrowing directly under this fascial sling. This study demonstrates that the fibromuscular sling of the soleus muscle may act as a potential compression site of the tibial nerve. These findings offer insight and potential hope for those patients who have persistent plantar numbness after tarsal tunnel decompression and for those patients with plantar numbness who also have weakness of toe flexion.

A review of plantar heel pain of neural origin: differential diagnosis and management

Plantar heel pain is a symptom commonly encountered by clinicians. Several conditions such as plantar fasciitis, calcaneal fracture, rupture of the plantar fascia and atrophy of the heel fat pad may lead to plantar heel pain. Injury to the tibial nerve and its branches in the tarsal tunnel and in the foot is also a common cause. Entrapment of these nerves may play a role in both the early phases of plantar heel pain and recalcitrant cases. Although the contribution of nerve entrapment to plantar heel pain has been well documented in the literature, its pathophysiology, diagnosis and management are still controversial. Therefore, the purpose of this article was to critically review the available literature on plantar heel pain of neural origin. Possible sites of nerve entrapment, effectiveness of diagnostic clinical tests and electrodiagnostic tests, differential diagnoses for plantar heel pain, and conservative and surgical treatment will be discussed.

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.

Nerves in a pinch: imaging of nerve compression syndromes

Nerve compression is a common entity that can result in considerable disability. Early diagnosis is important to institute prompt treatment and to minimize potential injury. Although the appropriate diagnosis is often determined by clinical examination, the diagnosis may be more difficult when the presentation is atypical, or when anatomic and technical limitations intervene. In these instances, imaging can have an important role in helping to define the site and etiology of nerve compression or in establishing an alternative diagnosis. MR imaging and ultrasound provide direct visualization of the nerve and surrounding abnormalities. For both modalities, the use of high-resolution techniques is important. Bony abnormalities contributing to nerve compression are best assessed by radiographs or CT. For the radiologist, knowledge of the anatomy of the fibro-osseous tunnels, familiarity with the causes of nerve compression, and an understanding of specialized imaging techniques are important for successful diagnosis of nerve compression.