Preoperative Ultrasound in Patients with Meralgia Paresthetica to Detect Anatomical Variations in the Course of the Lateral Femoral Cutaneous Nerve.

OBJECTIVE: Sometimes during surgery for meralgia paresthetica, it can be difficult to find the lateral femoral cutaneous nerve (LFCN). The aims of this study were to study the prevalence of different anatomical variations in patients, compare preoperative ultrasound (US) data with intraoperative findings, and investigate the effect of type of anatomical variation on duration of surgery and success rate of localizing the LFCN. METHODS: Fifty-four consecutive patients with idiopathic meralgia paresthetica who underwent either a neurolysis or neurectomy procedure were included. All patients preoperatively underwent US of the LFCN. Anatomical variations were categorized into type A, B, C, D, and E using the classification of Aszmann and Dellon. The cross-sectional area of the LFCN at the inguinal ligament and the distance of the LFCN to the anterior superior iliac spine were noted. Correlations with intraoperative findings were investigated, as well as the effect on duration of surgery and success rate of finding the LFCN. Clinical outcome was assessed using the Likert scale. RESULTS: The most frequent anatomical variant was type B (79%), followed by type C (9%), D (5%), and E (7%). No type A was encountered. Correlation between preoperative US and intraoperative findings was 100%. During surgery, the LFCN could be identified in all cases. Duration of surgery did not significantly vary for the different anatomical variants. CONCLUSIONS: Preoperative US is reliable in detecting anatomical variations of LFCN. This information can be very helpful in identifying the LFCN more frequently and easily during surgery, especially in more medial variants.

Femoral nerve split with variant iliacus muscle: a potential source of femoral nerve entrapment.

The iliacus muscle is a large, flat, triangle-shaped muscle located in the iliac fossa. This muscle forms part of the iliopsoas muscle complex. Although anatomical variations of iliacus muscles are rare, some variations are clinically important due to the possible coexistence of an unusual course of the femoral nerve. The femoral nerve is the largest branch of the lumbar plexus and supplies the muscles and skin in the anterior aspect of the thigh. We encountered a case of a single aberrant slip of the iliacus muscle piercing the femoral nerve in the left iliac fossa of a male cadaver aged 97 years. The potential clinical importance of this variant iliacus muscle accompanied by a femoral nerve split would be femoral neuropathy and possible consequent alterations of sensation in the anterior and medial aspects of the thigh or motor deficit of the quadriceps muscle.

Ultrasound-Guided Diagnosis and Injection of the Lateral Femoral Cutaneous Nerve with an Anatomical Variation.

Meralgia paresthetica (MP) is an entrapment neuropathy of the lateral femoral cutaneous nerve (LFCN). There are many variations in the course of the LFCN. A 55-year-old woman presented with pain and tingling sensations on the anterolateral aspect of her left thigh. Physical examination revealed hypoesthesia of the proximal anterolateral thigh on the left side. During the electrodiagnostic study, sensory nerve action potential of the LFCN could not be obtained on both sides. Through those clinical and electrophysiological findings, we prediagnosed the case as MP and planned to perform diagnostic nerve block. For the injection to perform, ultrasonography was used. During the ultrasonographic evaluation, the left LFCN was visualized lateral to the anterior superior iliac spine (ASIS). Then ultrasound-guided nerve block with 2 cc lidocaine 2% for diagnostic purpose was performed in this region. Immediately after the injection, the patient's complaints relieved completely, and hence the patient was diagnosed as having MP with an LFCN anatomical variation. Two months later her complaints persisted, and ultrasound-guided LFCN injection with 2 mL of lidocaine 2% + 1 cc of betametazone was performed. One month after the second injection, her complaints were relieved markedly and she resumed her daily activities. In conclusion, the course of the LFCN is quite variable. We present a relatively rare anatomical variation of the LFCN, crossing lateral to the ASIS, diagnosed with ultrasonography. Ultrasonography can be performed to visualize the LFCN, especially a nerve with an anatomical variation.

Anatomical variation of sciatic nerve: a case report of high division and unusual anastomosis with the posterior femoral cutaneous nerve

The posterior femoral cutaneous nerve is a sensitive nerve that rises from S1-S3, usually giving off cutaneous branches for the gluteal region, perineum, the posterior region of the thigh and leg. The sciatic nerve is the largest nerve in the human body, rising from L4-S3, and divides into the tibial and common fibular nerves, innervating the muscles from the posterior compartment of the thigh. Anastomosis between the sciatic nerve and the posterior femoral cutaneous nerve is rare. During dissection of the right gluteal region on a male cadaver fixed with 10% formalin, we observed an anastomosis between both nerves, while the common fibular nerve perforated the piriformis muscle, dividing it in two muscle slips. Both nerves trajectories were within the regular pattern after this communication. Our aims were to describe this unusual case of anastomosis and perform a literature review on the variations of the sciatic nerve, while also discussing their clinical significance

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Classification and fascicular analysis of variant branching pattern of femoral nerve for microsurgical intervention: a series of thirteen cadavers / Clasificación y análisis fascicular de las variantes en el patrón de ramificación del nervio femoral en intervenciones microquirúrgicas: una serie de 13 cadáveres

Femoral neuropathy associated with lower limb is treated by surgical intervention through activation/regeneration/grafting of nerve fibers by a nerve cuff electrode implant or neuro-prosthesis. These procedures require detailed and precise knowledge of neuro-anatomical variants of the femoral nerve and its fascicular anatomy so that the nerve injury can be investigated and treated more efficiently. The aim of the study is to uncover the variations both in the femoral nerve and its branches, to classify them and to bring out corresponding fascicular anatomy using a hypothesis based on the principle of consistency, continuity and traceability of fascicles. The study was carried out in the Department of Anatomy AIIMS Rishikesh using 13 matched lower limbs (26 femoral nerves) from 13 cadavers. The femoral nerve was exposed in the femoral triangle and traced to the posterior abdominal wall. Variations in the shape, size and course of the femoral nerve and its branches were analyzed. The fascicular arrangement was also conceptualized based on the hypothesis. Seven classes, high division, trunk anomaly, semi-scattered, scattered branching pattern, pectocutaneous, lateral cutaneous nerve of thigh and nerve to sartorius anomalies were detected. The corresponding fascicular organizations were modeled. The seven classes along with corresponding fascicular pattern will be very useful for neurosurgeons, radiologists, anesthetists and anatomists in diagnosis and treatment of femoral neuropathy.

La neuropatía femoral asociada con el miembro inferior es tratada por intervención quirúrgica a través de activación, regeneración e injerto de fibras nerviosas mediante un implante de electrodo de manguito de nervios o neuro-prótesis. Estos procedimientos requieren un conocimiento detallado y preciso de las variantes neuro-anatómicas del nervio femoral y su anatomía fascicular de modo que la lesión del nervio pueda ser investigada y tratada de manera más eficiente. El objetivo del estudio fue descubrir las variaciones tanto en el nervio femoral y sus ramas y clasificarlos a partir de la anatomía fascicular utilizando una hipótesis basada en el principio de la continuidad y trazabilidad de los fascículos correspondientes. El estudio se llevó a cabo en el Departamento de Anatomía AIIMS Rishikesh utilizando 13 miembros inferiores pareados (26 nervios femorales) de 13 cadáveres. El nervio femoral se expuso en el triángulo femoral y fue trazado en la pared abdominal posterior. Se analizaron las variaciones en la forma, tamaño y trayecto del nervio femoral y sus ramas. El patrón fascicular fue conceptulizado de acuerdo a la hipótesis planteada. Se detectaron anomalías clasificadas en: siete clases, división alta, anomalías de tronco, semi-dispersos, patrón de ramificación dispersa, pectocutáneo, nervio cutáneo lateral y nervio del músculo sartorio. Las clasificaciones junto con el patrón fascicular correspondientes serán de gran utilidad para los neurocirujanos, radiólogos, anestesistas y anatomistas en el diagnóstico y tratamiento de la neuropatía femoral.

Anatomical Variations of the Lateral Femoral Cutaneous Nerve and Iatrogenic Injury After Autologous Bone Grafting From the Iliac Crest.

OBJECTIVE: We describe 2 patients with surgical injury to the lateral femoral cutaneous nerve (LFCN) after bone harvesting from the iliac crest for autologous bone grafting. DESIGN: A case-series of 2 patients and literature study of all anatomical variants of the LFCN in relation to the anterior superior iliac spine and inguinal ligament. SETTING: A teaching hospital in The Hague, the Netherlands. PATIENTS: Two patients with surgical injury to the LFCN after bone harvesting from the iliac crest for autologous bone grafting. RESULTS: All 9 known anatomical variations of the LFCN in the literature are reviewed, and the importance of these anatomical variations for surgeons and anesthetists is stressed. CONCLUSIONS: For every trauma, orthopedic, plastic, and cranio-maxillofacial surgeon and anesthesiologist it is important to know the anatomy of the LFCN and its known variations. To prevent injury of the LFCN during bone harvesting, the bone should be harvested 4-5 cm posterior to the anterior superior iliac spine and the incision should be parallel to the iliac crest. LEVEL OF EVIDENCE: Therapeutic Level V. See Instructions for Authors for a complete description of levels of evidence.

Variable origin and ramification pattern of the lateral femoral cutaneous nerve: a case report and neurosurgical considerations.

Variations in the anatomy of the lateral femoral cutaneous nerve (LFCN) have been reported in the literature. LFCN is vulnerable to injury during several surgical operations, therefore any surgeon intervening in the area should be familiar to its topographic variability. Lesion of the nerve leads to a condition known as "meralgia paresthetica". We present a cadaveric case of a variant LFCN where two LFCN branches were encountered arising from the lumbar plexus. In specific the anterior LFCN branch originated from the femoral nerve, whereas at the level of the inguinal ligament, four nerve branches were present. The existence of multiple LFCN branches could lead to diagnostic confusion in case of "meralgia paresthetica", while if the neurosurgeon is not aware of the potential variability during surgical decompression of the nerve, postoperative complications may occur. The supernumerary LFCN branches could be identified by ultrasound imaging and be used as optimum vascularized grafts for sensory nerve repair.

Topographical anatomy of the profunda femoris artery and the femoral nerve: normal and abnormal relationships.

BACKGROUND AND OBJECTIVE: Femoral nerve (FN) is the largest branch of lumbar plexus. It lies lateral to femoral artery (FA) and it is located outside the femoral sheath. Profunda femoris artery (PFA) is a branch of the FA. The present study aimed to observe the topographical anatomy and relationship of the PFA and the FN. MATERIALS AND METHODS: A total of 12 embalmed cadaveric lower limbs (7 lefts and 5 rights) were taken and the thighs were dissected in detail. The relationship of PFA and FN were observed. Appropriate measurements were taken and the specimens were photographed. RESULTS: The PFA originated from the FA in all the 12 specimens (100%). In 10 specimens (83.3%), the PFA was found to originate lateral to the FA while in 2 specimens, the origin of PFA was posterior to the FA (16.7%). The PFA originated from the FA at a distance of 6.5 + 1.5 cm with regard to the midinguinal point. All FN were found to lie outside the femoral sheaths. Out of the 12 specimens, only 2 specimens (16.7%) exhibited the FN to lie posterior to the PFA, while in 10 specimens (83.3%), the FN was found to lie anterior to the PFA. CONCLUSION: Prior anatomical knowledge of structures in the anterior compartment of thigh may be helpful for surgeons performing nerve block, cannulation and catheterization. Knowledge of abnormal anatomy of the FN and PFA is important in order to prevent any inadvertent injury to the PFA or FN.

Ultrasound of the lateral femoral cutaneous nerve in asymptomatic adults.

BACKGROUND: To define the sites where the lateral femoral cutaneous nerve (LFCN) is more easily visualized and to describe the anatomical variations of the LFCN. METHODS: A total of 240 LFCNs in 120 volunteers were evaluated with 18 MHz ultrasound; the intermuscular space between the tensor fasciae latae muscle and the sartorius was used as an initial sonographic landmark. The time taken to identify the nerve was recorded. The number of nerve branches at the level of the inguinal ligament (IL) and the relationship between the LFCN and the IL was assessed. The nerve cross-sectional area (CSA) of the LFCN and the distance between the LFCN and the anterior superior iliac spine was measured. RESULTS: Each nerve was identified using ultrasound in all participants. The mean time for identifying the nerve was 7s for unilateral LFCNs. The nerve passed under the IL in 198 cases, whereas in 44 cases, it passed through to the IL. The LFCN consisted of 1-4 branches just after its passage under or through the IL. The CSA of the LFCN was 1.04 ± 0.44 mm(2), and the mean distance between the LFCN and the anterior superior iliac spine was 15.6 ± 4.2 mm. CONCLUSIONS: It is easier to identify the LFCN if the intermuscular space between the tensor fasciae latae muscle and the sartorius is used as an initial sonographic landmark. The anatomical variation of the LFCN can be viewed with high-frequency ultrasound.

Anatomical variation of the lateral femoral cutaneous nerve: a case report and review of the literature.

We describe a rare anatomical variation of the lateral femoral cutaneous nerve (LFCN) in a 29-year old female patient discovered during a surgical decompression of the LFCN for meralgia paresthetica. Anatomical variations of the LFCN must always be considered at the time of surgery to maximize success rate and avoid nerve damage during surgical dissection.

Anomalous higher branching pattern of the femoral nerve: a case report with clinical implications.

The femoral nerve usually divides into anterior and posterior branches below the inguinal ligament. In the present case, we report the anomalous higher branching pattern of the femoral nerve on both sides of a 52 year male cadaver. The femoral nerve divided into the anterior and posterior branches above the inguinal ligament. Such a higher division of femoral nerve is a rare finding and it may be important for surgeons, orthopaedicians and anaesthetists in day to day clinical practice.

Variant slips of psoas and iliacus muscles, with splitting of the femoral nerve.

In bilateral dissections of 68 cadavers, four examples were found unilaterally of variant slips of iliacus and psoas major muscles. In three of them the femoral nerve was pierced by the variant slip. One of these variants was a previously undocumented accessory slip of iliacus, originating from the iliolumbar ligament, passing inferiorly anterior to iliacus, and traversing the femoral nerve; its tendon split to be attached proximally to the lesser trochanter of the femur and distally to an unknown insertion. Such anomalies might cause tension on the femoral nerve resulting in referred pain to the hip and knee joints and to the lumbar dermatomes L2,3 and 4.