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Normal anatomy of the sciatic nerve. (a) Axial T1weighted MR image (repetition time msec/ echo time msec = 553/12) shows the fascicular composition of the sciatic nerve (arrow). (b) Coronal T1-weighted MR image (713/25) shows the abundant perifascicular fat of the sciatic nerve (arrows).
Source publication
Entrapment neuropathies can manifest with confusing clinical features and therefore are often underrecognized and underdiagnosed at clinical examination. Historically, electrophysiologic evaluation has been considered the mainstay of diagnosis. Today, cross-sectional imaging, particularly magnetic resonance (MR) imaging and specifically MR neurogra...
Contexts in source publication
Context 1
... nerves appear as singular or bundled longitudinally oriented structures, with intermedi- ate signal intensity on T1-weighted images and im- ages obtained with fluid-sensitive sequences. Large nerves are easiest to identify because of abundant perifascicular fat and because of greater fascicular composition (40-60 fascicles in the case of the sci- atic nerve, one or two fascicles in the proper digital nerve) (Fig 1) (1). Perifascicular and perineu- ral high signal intensity from fat makes nerves conspicuous on T1-weighted images and provides a model road map. ...
Context 2
... neuropathy secondary to iliopsoas compartment masses and a distended iliopsoas bursa has also been described (16). signal intensity changes in the pectineus and sar- torius muscles and the quadriceps muscle group (Fig 11) (17). ...
Context 3
... the latter case, prolonged lithotomy position during genitourologic surgeries and excessive retraction during total hip replacement surgery are reported (20). Mass effect on the nerve commonly occurs around the region of the obturator canal or as the nerve enters the thigh and may be related to pelvic trauma, periarticular cysts or bursae, or hernia (Fig 13). ...
Context 4
... MR imaging, mass effect on the nerve (eg, by a hematoma, fracture, bursa, tumor, metastasis, or periacetabular screws and cement) as well as in- filtration of the fat around the nerve just proximal to and within the obturator canal can be appreci- ated (Fig 14). Infectious or inflammatory pro- cesses involving the symphysis pubis, particularly osteitis pubis, may secondarily involve the nerve in the obturator canal and manifest as infiltration of the perineural fat. ...
Context 5
... Anatomy and Imaging.-Formed by the L4-S3 nerve roots, the sciatic nerve (Figs 1, 16) is the largest nerve in the body. The nerve exits the greater sciatic foramen as distinct tibial and peroneal divisions, enclosed in a common nerve sheath. ...
Context 6
... sciatic nerve is the lifeline of the lower ex- tremity. It provides knee flexion by innervation of the posterior thigh muscles (Fig 15) and almost all sensory and motor functions below the knee. The tibial nerve provides all motor function to the posterior compartment of the leg and to the plantar muscles of the foot, while the common peroneal nerve provides motor function to the anterior and lateral compartments of the leg. ...
Context 7
... of its large size and abundant perineu- ral fat, the sciatic nerve is easy to evaluate in all imaging planes (Fig 1). The nerve has intermedi- ate signal intensity on T1-weighted images and mildly high signal intensity on fluid-sensitive ...
Context 8
... obturator nerve provides motor innerva- tion to the muscles of the adductor compartment (Fig 15), and muscle changes related to dener- vation may be seen. It is particularly important to distinguish muscle strain from acute muscle denervation in the athlete with groin pain, as ad- ductor tendinopathy may coexist with or lead to obturator neuropathy (22). ...
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normally appear ne...
Purpose:
The purpose of this study was to evaluate the use of an ultrasound guided femoral nerve (FN) block together with an ultrasound guided lateral femoral cutaneous nerve (LFCN) block in addition to a patient controlled intravenous analgesia (PCIA) pump with piritramide as a strategy for postoperative pain-management after primary hip arthropl...
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Citations
... Common sites of lower extremity peripheral neuropathy include areas of anatomic narrowing through which a nerve traverses, such as fibro-osseous or fibromuscular tunnels ( Fig. 1) (3) . Although peripheral neuropathy is generally a clinical diagnosis based mainly on clinical history, physical exam, and electrophysiologic testing, crosssectional imaging, particularly magnetic resonance neurography (MRN) and high-resolution ultrasound (US), has come to play an increasingly important role in the diagnostic work up of neuropathies, helping to make accurate diagnoses and direct more precise clinical management (4) . Shear-wave elastography is a more recent sonographic technique that helps to detect regions of nerve stiffness. ...
Lower extremity peripheral neuropathy is a commonly encountered neurologic disorder, which can lead to chronic pain, functional disability, and decreased quality of life for a patient. As diagnostic imaging modalities have improved, imaging has started to play an integral role in the detection and characterization of peripheral nerve abnormalities by non-invasively and accurately identifying abnormal nerves as well as potential causes of neuropathy, which ultimately leads to precise and timely treatment. Ultrasound, which has high spatial resolution and can quickly and comfortably characterize peripheral nerves in real time along with associated denervation muscle atrophy, and magnetic resonance neurography, which provides excellent contrast resolution between nerves and other tissues and between pathologic and normal seg- ments of peripheral nerves, in addition to assessing reversible and irreversible muscle denervation changes, are the two mainstay imaging modalities used in peripheral nerve assessment. These two modalities are complimentary, and one may be more useful than the other depending on the nerve and location of pathol- ogy. Imaging must be interpreted in the context of available clinical information and other diagnostic stud- ies, such as electrodiagnostic tests. Here, we offer a comprehensive overview of the role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of the peripheral nerves of the lower extremity and their associated neuropathies.
... In cases of neuropathy, the nerve signal increases abnormally, approaching the fluid signal of adjacent vessels; on T2-weighted imaging, the fascicular pattern is lost, or hypertrophy of some or all of the fascicles may be observed [19]. ...
In the present study, through a case series, we highlighted the role of magnetic resonance (MR) in the identification and diagnosis of peripheral neuropathies. MR neurography allows the evaluation of the course of nerves through 2D and 3D STIR sequences with an isotropic voxel, whereas the relationship between nerves, vessels, osteo-ligamentous and muscular structures can be appraised with T1 sequences. Currently, DTI and tractography are mainly used for experimental purposes. MR neurography can be useful in detecting subtle nerve alterations, even before the onset of symptoms. However, despite being sensitive, MR neurography is not specific in detecting nerve injury and requires careful interpretation. For this reason, MR information should always be supported by instrumental clinical tests.
... • chronic compression exerted by the sartorius in dancers. 25 • iatrogenic injuries: in particular, during the direct anterior approach for hip arthroplasty, for which US has been proposed as a preoperative tool to prevent damage and identify the nerve courses. 26 The nerve can also be injured during other regional surgery, such as hernia repair. ...
We review the ultrasound (US) findings in patients who present with meralgia paresthetica (MP). The anatomy of the lateral femoral cutaneous nerve at the level where the nerve exits the pelvis and potential entrapment sites that can lead to MP are discussed. A wide range of pathological cases are presented to help in recognizing the US patterns of MP. Finally, our experience with US‐guided treatment is discussed.
... It should be noted that the textbooks and manuals on anatomy indicate that in the skin of the lateral and anterior-lateral femoral surfaces the lateral femoral cutaneous nerve divides, the skin of the upper-medial femoral surface under the inguinal ligament is innervated by the femoral branch of the genitofemoral nerve, the skin of the lower portion of the medial femoral surface -by the cutaneous branch of the obturator nerve and anterior cutaneous branches of the femoral nerve innervate the anterior femoral surface skin [9,16]. However, as a result of the study, anatomical variability in the innervation of the skin of the anterior femoral region was found. ...
Objective:
The aim: Is to find out the features of innervation of the skin of the anterior femoral region and the fascia lata during the fetal period of human development.
Patients and methods:
Materials and methods: The study was carried out on 64 preparations of the lower extremities of human fetuses of 4-10 months using macromicroscopic preparation and morphometry. Macropreparations of the skin nerves of the lower extremities of different age fetuses with anatomical variants were subject to photo documentation.
Results:
Results: The features of cutaneous nerve fetal topography of the anterior femoral region and the broad fascia of the femur were revealed, their connections were established, and their layering was determined. It was found that in human fetuses, not only the lateral cutaneous femoral nerve but in most cases the branches of other nerves of the lumbar plexus, except for the obturator nerve, are directed to the skin of the anterior-lateral femur surface. The innervation of the medial femur surface is provided by the following nerve complex: obturator, femoral, saphenous and genitofemoral nerves.
Conclusion:
Conclusions: Taking into account the fact that the terminal branches of adjacent cutaneous nerves of the femoral region intersect and overlap, innervation bypasses are formed, due to which, in case of possible damage to one of the nerves, its insufficiency is compensated to a certain extent. Anastomoses were found between the cutaneous nerves, in the form of loops of various shapes and sizes, namely: between the cutaneous-fascia branches of the femoral and ilioinguinal nerves and the femoral and obturator nerves.
... Colorectal, gynecological, and other malignant conditions of the pelvis can reach up to the pelvic sidewall and infiltrate or compress the sacral plexus. Infectious and inflammatory arthritis of sacroiliac joints, pelvic irradiation, vascular aneurysms, pelvic trauma, and pelvic surgery are other infrequent causes [9]. ...
... Overall, pain, sensory deficits, weakness of proximal muscles, and loss of deep tendon reflexes dominate the clinical picture [10]. Incontinence of the bladder and bowel mimicking cauda equina syndrome is noted occasionally [9]. ...
... The obturator nerve is most commonly entrapped in the obturator canal, and the common causes are pelvic trauma (Fig. 5), periarticular cysts, peri-labral cysts, bursae, or obturator hernia [9]. The iatrogenic injuries, in conjunction with femoral nerve (FN), can complicate hip arthroscopy and female mid-urethral sling placement surgeries for stress incontinence [35,36]. ...
Purpose
This review discusses the relevant anatomy, etiopathogenesis, current notions in clinical and imaging features as well as management outline of lower limb entrapment neuropathies.
Methods
The review is based on critical analysis of the current literature as well as our experience in dealing with entrapment neuropathies of the lower limb
Results
The complex anatomical network of nerves supplying the lower extremities are prone to entrapment by a heterogenous group of etiologies. This leads to diverse clinical manifestations making them difficult to diagnose with traditional methods such as clinical examination and electrodiagnostic studies. Moreover, some of these may mimic other common conditions such as disc pain or fibromyalgia leading to delay in diagnosis and increasing morbidity. Addition of imaging improves the diagnostic accuracy and also help in correct treatment of these entities. Magnetic resonance imaging is very useful for deeply situated nerves in pelvis and thigh while ultrasound is well validated for superficial entrapment neuropathies.
Conclusion
The rapidly changing concepts in these conditions accompanied by the advances in imaging has made it essential for a clinical radiologist to be well-informed with the current best practices.
... При поражении общего малоберцового нерва сенсорные нейрограммы ПМН могут быть в норме в отличие от нейрограмм глубокого малоберцового нерва, на которых обычно имеются выраженные изменения. Все это служит доказательством того, что волокна глубокого малоберцового нерва обладают селективной уязвимостью в отношении сдавления и растяжения [17]. ...
... Sensory neurograms of the SPN could show physiological parameters even with a CPN lesion (during which DPN neurograms are significantly pathological). This proves the selective vulnerability of the fibers of the deep peroneal nerve to compression and stretch [17]. ...
... Более того, к этому исследованию имеются и противопоказания. Нейрография под ультразвуковым контролем -неинвазивная и сравнительно недорогая методика, позволяющая визуализировать нерв на всем протяжении в динамике в течение довольно and enables the dynamic demonstration of the nerve, which is important while diagnosing such conditions as myofascial herniation, a tissue scar or orthopedic hardware [17,19]. ...
Isolated neuropathy of the superficial peroneal nerve (SPN) is a relatively rare type of peripheral neuropathy. It is linked to the mechanical entrapment of the SPN in predisposed locations of its anatomical pathway. Associated clinical findings are insufficient lifting of the latero-dorsal part of the foot, stepping on the lateral border of the foot, and commonly, a strong pain localized in the nerve dermatome.
Case report . We describe a case of a 14-year-old female patient with right leg pain lasting 24 months. Repeated neurological examinations with negative findings on electromyography (EMG) were performed. The patient underwent a Steindler surgery for a suspected diagnosis of a heel spur, without any improvement. Despite complex pharmacotherapy, chronic pain developed. The patient was unable to walk, being bound to a wheelchair. Amputation of her lower limb under the knee was also considered. SPN entrapment was diagnosed at a physical examination at EuroPainClinics. Decompression of the SPN under local anaesthesia was performed at the clinic.
Results . The symptoms improved immediately after the procedure, and following 2 months of rehabilitation, the patient was completely symptom-free. Her clinical state remains unchanged until this day.
Conclusions . SPN entrapment is not a common diagnosis in the group of pain syndromes. Regarding the lower limb, it is imperative to include it on the list of differential diagnoses in cases of pain and functional disorders of the lateral muscle groups of the calf and leg. In the case of SPN entrapment, EMG findings may be negative.
... The most common variations are related to the anatomic relationship with the sciatic nerve. 4 An accessory piriformis can exist, which may present as piriformis syndrome because of entrapment of the sciatic nerve at the sciatic notch. 4,6 Other anatomic variants include a bifid piriformis and fusion with the adjacent gluteal, obturator or gemilli muscles. ...
... 4 An accessory piriformis can exist, which may present as piriformis syndrome because of entrapment of the sciatic nerve at the sciatic notch. 4,6 Other anatomic variants include a bifid piriformis and fusion with the adjacent gluteal, obturator or gemilli muscles. Clinical presentation of such variants is unknown. ...
Agenesis of the piriformis muscle is an extremely rare occurrence. Knowledge about this anatomic variant is important because of its close proximity with the sciatic nerve and sacral plexus. The piriformis muscle also serves as an important anatomic landmark for image-guided intervention and hip surgery. We report a case of piriformis muscle agenesis in a 28-year-old woman, incidentally detected on magnetic resonance imaging of the lumbosacral spine and pelvis, performed for low back pain.
... 2 Traditionally, the small peripheral nerves have been difficult to assess on magnetic resonance imaging (MRI), but the development of 3-Tesla (3T) magnetic resonance neurography (MRN) now makes the pathology of these nerves more conspicuous. 3,4,5 ...
... 4 The wearing of tight clothing, belts and corsets, as well as causes of increased intraabdominal pressure such as pregnancy and obesity, may exert direct pressure on the nerve, resulting in an entrapment neuropathy. 1,2,3,4 Metabolic causes are associated with diabetes mellitus, alcoholism, lead poisoning and hypothyroidism. 1,2 Iatrogenic causes include various orthopaedic surgical procedures such as iliac-crest bone graft procedures, anterior pelvic surgery, prone position for spinal surgical procedures and total hip arthroplasty. ...
... An increase in nerve size, loss of the normal appearance of nerve fascicles and surrounding fat stranding support the findings of nerve injury, but these morphological changes may be more difficult to detect in smaller, more peripheral nerves such as the LFCN. 3 Motor neuropathies may also be supported by the findings of muscle oedema in a specific nerve distribution, in the acute phase of denervation. This finding will not be present in the purely sensory nerve neuropathy such as in the LFCN in meralgia paresthetica. ...
Meralgia paresthetica is a neuropathy of the lateral femoral cutaneous nerve. Traditionally, the diagnosis is based on classical symptoms and signs. In cases where there is a diagnostic dilemma, the role of magnetic resonance imaging has been to exclude other causes for the patient’s presentation, as the small extraspinal peripheral nerves were not well visualised at imaging. The development of 3-Tesla magnetic resonance neurography, however, has made pathology of these nerves more conspicuous.
... These and other locations are also often volumetrically constrained with little loose connective tissue so an NCE should be as thin as possible to avoid adding unnecessary bulk to an already tight area. Examples include the sciatic [39], pudendal [40], and superior gluteal [41] nerves in the pelvis and gluteal space [42], as well as the axillary nerve in the axilla [34] and several areas of the brachial plexus, which is closely related to several bony structures against which it may be compressed [38,43]. Clinical experience has also indicated that NCE bulk should be minimized when implanting NCEs in superficial locations [17]. ...
Objective:
As neural interfaces demonstrate success in chronic applications, a novel class of reshaping electrodes with patterned regions of stiffness will enable application to a widening range of anatomical locations. Patterning stiff regions and flexible regions of the electrode enables nerve reshaping while accommodating anatomical constraints of various implant locations ranging from peripheral nerves to spinal and autonomic plexi.
Approach:
Introduced is a new composite electrode enabling patterning of regions of various electrode mechanical properties. The initial demonstration of the composite's capability is the composite flat interface nerve electrode (C-FINE). The C-FINE is constructed from a sandwich of patterned PEEK within layers of pliable silicone. The shape of the PEEK provides a desired pattern of stiffness: stiff across the width of the nerve to reshape the nerve, but flexible along its length to allow for bending with the nerve. This is particularly important in anatomical locations near joints or organs, and in constrained compartments. We tested pressure and volume design constraints in vitro to verify that the C-FINE can attain a safe cuff-to-nerve ratio (CNR) without impeding intraneural blood flow. We measured nerve function as well as nerve and axonal morphology following 3 month implantation of the C-FINE without wires on feline peripheral nerves in anatomically constrained areas near mobile joints and major blood vessels in both the hind and fore limbs.
Main results:
In vitro inflation tests showed effective CNRs (1.93 ± 0.06) that exceeded the industry safety standard of 1.5 at an internal pressure of 20 mmHg. This is less than the 30 mmHg shown to induce loss of conduction or compromise blood flow. Implanted cats showed no changes in physiology or electrophysiology. Behavioral signs were normal suggesting healthy nerves. Motor nerve conduction velocity and compound motor action potential did not change significantly between implant and explant (p > 0.15 for all measures). Axonal density and myelin sheath thickness was not significantly different within the electrode compared to sections greater than 2 cm proximal to implanted cuffs (p > 0.14 for all measures).
Significance:
We present the design and verification of a novel nerve cuff electrode, the C-FINE. Laminar manufacturing processes allow C-FINE stiffness to be configured for specific applications. Here, the central region in the configuration tested is stiff to reshape or conform to the target nerve, while edges are highly flexible to bend along its length. The C-FINE occupies less volume than other NCEs, making it suitable for implantation in highly mobile locations near joints. Design constraints during simulated transient swelling were verified in vitro. Maintenance of nerve health in various challenging anatomical locations (sciatic and median/ulnar nerves) was verified in a chronic feline model in vivo.
... Die Unterscheidung zwischen sensiblen und motorischen Ausfällen und die klinischneurologische Erfassung der betroffenen Regionen und Muskulatur helfen dabei, die lädierten Nerven aufzusuchen und die Pathologie zu finden [12]. Das klinische Bild kann komplex sein durch eine Kombination von Muskelgruppenausfällen, sensorischen Veränderungen und (selten) Darm-und Blaseninkontinenz sowie sexueller Dysfunktion [9,24]. Eine lumbosakrale Plexopathie kann durch primäre Veränderungen der neuralen Strukturen selbst oder Kompression oder Infiltration von außen verursacht werden [27]. ...
... Mithilfe der MR-Traktographie (e) stellte sich eine vollständige Kontinuitätsunterbrechung des Nervs proximal der maximalen Verdickung dar gungen in Plexopathien resultieren [17]. Für die Diagnostik ist eine unilaterale Lokalisation der Symptome in der Regel ein Indikator für eine lokale Beteiligung, während eine bilaterale Symptomatik auf einen systemischen Prozess hinweist [24]. ...
BACKGROUND
Technical advances in magnetic resonance (MR) and ultrasound-based neurography nowadays facilitate the radiological assessment of the lumbosacral plexus.
OBJECTIVE
Anatomy and imaging of the lumbosacral plexus and diagnostics of the most common pathologies.
MATERIAL AND METHODS
Description of the clinically feasible combination of magnetic resonance imaging (MRI) and ultrasound diagnostics, case-based illustration of imaging techniques and individual advantages of MRI and ultrasound-based diagnostics for various pathologies of the lumbosacral plexus and its peripheral nerves.
RESULTS
High-resolution ultrasound-based neurography (HRUS) is particularly valuable for the assessment of superficial structures of the lumbosacral plexus. Depending on the examiner's experience, anatomical variations of the sciatic nerve (e. g. relevant in piriformis syndrome) as well as more subtle variations, for example as seen in neuritis, can be sonographically depicted and assessed. The use of MRI enables the diagnostic evaluation of more deeply located nerve structures, such as the pudendal and the femoral nerves. Modern MRI techniques, such as peripheral nerve tractography allow three-dimensional depiction of the spatial relationship between nerves and local tumors or traumatic alterations. This can be beneficial for further therapy planning.
CONCLUSION
The anatomy and pathology of the lumbosacral plexus can be reliably imaged by the meaningful combination of MRI and ultrasound-based high resolution neurography.
