Femoral nerve compression caused by a hibernoma in the right thigh: a case report and literature review.

BACKGROUND: A hibernoma, also known as a brown fat tumor, is a rare benign soft tissue tumor, which originates from brown adipose tissue remaining in the fetus after the gestational period. It is often detected in adult men, presenting as a painless slow-growing mass. Hibernomas of the thigh have been reported; however, motor and sensory disorders caused by the tumors compressing the femoral nerve have not been reported. We report a case of a histopathologically proven hibernoma that induced femoral mononeuropathy. CASE PRESENTATION: A 26-year-old man was admitted to the hospital due to a mass, approximately 11.0 × 9.0 × 4.0 cm in size, that had developed 5 years ago in the anterolateral aspect of the proximal thigh. Furthermore, he had a history of hypoesthesia 1 month prior to his admission. He had signs and symptoms of both a motor and sensory disorder, involving the anterior aspect of the right thigh and the medial aspect of the calf, along the distribution of the femoral nerve. During surgery, the femoral nerve was found to be compressed by the giant tumor. The resultant symptoms probably caused the patient to seek medical care. Marginal resection of the mass was performed by careful dissection, and the branches of the femoral nerve were spared. Histopathology examination showed findings suggestive of a hibernoma. At the 4-month follow-up, no femoral nerve compression was evident, and local tumor recurrence or metastasis was not found. CONCLUSIONS: Asymptomatic hibernomas do not require treatment; however, in cases of hibernomas with apparent symptoms, complete marginal surgical excision at an early stage is a treatment option because it is associated with a low risk of postoperative tumor recurrence.

Ultrasound-Guided Injections at the Lateral Femoral Cutaneous Nerve: The Inguinal Ligament as a Barrier.

BACKGROUND: Ultrasound-guided perineural injections at the lateral femoral cutaneous nerve (LFCN) may confirm the correct diagnosis and provide symptom relief in meralgia paresthetica. Although correct visualization of the nerve is generally described as feasible, failure rates of the procedure may be as high as 30%. OBJECTIVES: This study investigated the spread of injected fluids in ultrasound-guided perineural injections at the LFCN. The aim of the study was to evaluate whether the inguinal ligament impedes the distribution of injected fluids along the course of the LFCN. STUDY DESIGN: We used a descriptive research design. SETTING: Research was conducted at an anatomical research facility. METHODS: In fresh, nonembalmed cadavers, 2 mL of ink were injected with ultrasound-guidance at the LFCN below the inguinal ligament. The course of the nerve was then dissected to show the extent of nerve staining. RESULTS: Spread of the injected ink proximal to the inguinal ligament was found in 67.65% of specimens, while the ink did not pass the inguinal ligament in 32.35%. Concerning proximal spread, specimen body mass index was not of any relevance. LIMITATIONS: This cadaver study is only a simulation of the real clinical setting and does not allow any insight into the efficacy of the injection in living patients. CONCLUSIONS: The inguinal ligament is a barrier in the distribution of injected fluids in about one-third of specimens. This might be a major cause of failure in ultrasound-guided injections. The results from our study are in line with previously published failure rates and our findings might provide the anatomic basis to advance injection techniques. KEY WORDS: Cadaver study; injection; lateral femoral cutaneous nerve; LFCN; meralgia paresthetica; nerve entrapment; sonography; ultrasound.

Meralgia paresthetica: finding an effective cure.

Meralgia Paresthetica (MP) is one of the most common mononeuropathies of the lower limb. MP usually resolves on its own, even without treatment. However, many physicians are not aware of this diagnosis and may confuse patients with another nerve disease such as radiculopathies. Although no motor symptoms are associated with this condition, the sensory dysfunctions are potentially debilitating to patients. The variable course of the lateral femoral cutaneous nerve also complicates treatments. Thus, the author recommends the use of ultrasonography to help locate the nerve. Many treatments for MP are available, but they are supported only by moderate to low-quality evidence. Treatments range from conservative to interventions using nerve blocks and surgery. Without a clear superiority of any treatment, the author concludes that treatment should be done in a stepwise fashion, from the noninvasive to the more invasive treatment if symptoms persist.

Anatomical Implications Regarding Femoral Nerve Palsy During a Direct Anterior Approach to Total Hip Arthroplasty: A Cadaveric Study.

BACKGROUND: Femoral nerve palsy is a serious neurological complication following total hip arthroplasty (THA) via a direct anterior approach. One hypothesis is that the nerve injury is caused by malpositioning of retractors over the anterior wall of the acetabulum. The purpose of this cadaveric study was to clarify the anatomical features of the femoral nerve around the anterior acetabular rim and the potential risk of nerve injury during a direct anterior approach to THA. METHODS: We dissected 84 cadaveric hips from 44 formalin-embalmed cadavers. When the cadavers were supine, the iliopsoas muscle and the femoral nerve were exposed and the anterior joint capsule and labrum were resected. The measurement points were determined along the acetabular rim every 30°, and a reference line was drawn from the anterior superior iliac spine to the center of the acetabulum, with the intersection of the rim at 0°. The minimum distance to the femoral nerve margin was measured from 0° to 150° (6 points). Other anatomical structures were measured to determine their association with the distance of the shortest measurement points. RESULTS: The mean minimum distances to the femoral nerve were 33.2 mm at 0°, 24.4 mm at 30°, 18.4 mm at 60°, 16.6 mm at 90°, 17.9 mm at 120°, and 23.2 mm at 150°, showing that the distance at 90° was the shortest (p < 0.001). The thickness of the iliopsoas muscle and the femoral length were positively associated with the distance to the femoral nerve at 90°. CONCLUSIONS: In this cadaveric study, the femoral nerve was within 16.6 to 33.2 mm of the acetabular rim at points from 0° to 150° of a line drawn from the anterior superior iliac spine. The nerve was closest to the rim at 90°, indicating that this is an area of high risk during retractor placement. CLINICAL RELEVANCE: Retractor placement at 90° to the anterior acetabular rim should be avoided to reduce the risk of femoral nerve injury.

Femoral nerve palsy following primary total hip arthroplasty with the direct anterior approach.

Nerve palsy following total hip arthroplasty (THA) can have a serious effect on a patient`s functional prognosis and on cost-effectiveness, and it is the leading cause of THA-associated medical litigation. However, only a few studies focus on femoral nerve palsy (FNP) following THA with the direct anterior approach (DAA). Moreover, several studies have reported that THA with DAA may result in higher complication rates, particularly during the so-called 'learning-curve period' for the surgeon. This study aimed to identify the incidence of FNP following primary THA with DAA, to determine presumed etiologies through a retrospective investigation of FNP clinical courses following primary THA with DAA and to identify any relationship between the occurrence of FNP following primary THA with DAA and the surgeon's experience of DAA. Since August 2007, DAA for primary THA was introduced in our institution. All 273 consecutive primary THAs with DAA (42 bilateral and 189 unilateral cases) between August 2007 and February 2014 were included in this study. All patients' charts and radiographs were reviewed to identify cases with palsy and to retrieve related factors. In this study, FNP was defined as weakness of the quadriceps femoris (manual muscle test <3) with or without sensory disturbance over the anteromedial aspect of the thigh. The incidence of FNP following primary THA with DAA was 1.1% (3/273 joints). In all 3 cases, the motor deficit recovered completely within a year. Suspected causes of the palsy in the 3 cases were believed to be improper positioning of the anterior acetabular retractor, excessive leg lengthening, or unknown etiology. There was no significant relationship between palsy and surgeon's experience of DAA. In THA with DAA for patients requiring major leg lengthening, the likelihood of FNP must be considered. To prevent FNP, the anterior acetabular retractor must be placed properly.

Histopathologic changes inside the lateral femoral cutaneous nerve obtained from patients with persistent symptoms of meralgia paresthetica.

BACKGROUND: In patients with persistent symptoms of meralgia paresthetica, a neurectomy of the lateral femoral cutaneous nerve (LFCN) can be performed to alleviate pain symptoms. The neurectomy procedure can be performed either as a primary procedure or after failure of a previously performed neurolysis or decompression of the LFNC (secondary neurectomy). The goal of the present study was to quantify the histopathologic changes inside the LFCN obtained from patients with persistent symptoms of meralgia paresthetica, and specifically to compare to what extend these changes are present after primary versus secondary neurectomy. METHODS: A total of 39 consecutive cases were analyzed microscopically: in 29 cases, the neurectomy had been performed as primary procedure, in 10 cases, after failed neurolysis. Intraneural changes were quantified for the (1) thickening of perineurium, (2) deposition of mucoid, and (3) percentage of collagen. Analysis was performed at three levels: proximal to, at, and distal to the previous site of compression. In addition, correlations were investigated for the duration of symptoms and the body mass index (BMI) of the patient. RESULTS: Intraneural changes were found consistently in all cases. There was no significant difference for the primary and secondary neurectomy groups. There was also no relation with the previous site of compression. There was a weak correlation between the occurrence of intraneural changes and the duration of symptoms, although this difference was not statistically significant. CONCLUSIONS: Histopathological changes in this study were found in all patients with persistent symptoms of meralgia paresthetica regardless of a previously performed neurolysis procedure. This finding suggests that the intraneural changes that occur in persistent meralgia paresthetica are largely irreversible and support the surgical strategy of neurectomy as an alternative to neurolysis, also for primary surgical treatment and not only after failure of neurolysis.

[Morphological study with ultrasound imaging in meralgia paraesthetica: in search of therapeutic efficiency]. / Estudio morfologico con ecografia en la meralgia parestesica: en busca de la eficiencia terapeutica.

TITLE: Estudio morfologico con ecografia en la meralgia parestesica: en busca de la eficiencia terapeutica.

Meralgia Paresthetica After Spine Surgery on the Jackson Table.

Meralgia paresthetica is a non-life-threatening neurological disorder characterized by numbness, tingling, and burning pain over the anterolateral thigh due to impingement of the lateral femoral cutaneous nerve. This disorder has been seen in patients with diabetes mellitus and obesity, but has also been observed in patients after procedures such as posterior spine surgery, iliac crest bone grafts, lumbar disk surgery, hernia repair, appendectomies, and pelvic osteotomies that ultimately lead to compression or damage to the lateral femoral cutaneous nerve. Overall, permanent sequelae of meralgia paresthetica are rare, however, some cases do require intervention.

Successful laparoscopic resection of a retroperitoneal schwannoma arising from the femoral nerve: A case report.

We report on a 45-year-old man who presented with pain in the left leg, which he had had for 2 months. A contrast-enhanced CT scan displayed a 25-mm tumor in the lateral side of the left psoas muscle. For this suspected retroperitoneal tumor, we performed laparoscopic resection of the tumor, which was encapsulated by the funicular femoral nerve, using surgical scissors rather than a surgical energy device and preserved the normal fascicles wherever possible. Pathological examination indicated a benign ancient schwannoma arising from the femoral nerve. The patient was able to return to his job 3 weeks after surgery, and he has shown no evidence of recurrence. This was thought to be because of the use of surgical scissors, rather than a surgical energy device, combined with visual magnification. Therefore, the laparoscopic approach is an effective and minimally invasive option for the resection of femoral nerve schwannoma.

Schwannoma extending from the umbilical region to the mid-thigh, compressing the major vessels of the right leg: A case report and review of the literature.

Schwannomas are benign, usually encapsulated, nerve sheath tumours derived from Schwann cells. They commonly arise from the cranial nerves as acoustic schwannomas and are extremely rare in the pelvis and retroperitoneal area (<0.5% of reported cases) unless they are combined with Von Recklinghausen disease (type 1 neurofibromatosis). We report the case of a 23-year-old woman with a mass extending from the umbilical region in the abdomen to the upper two-thirds of the thigh. As this tumour is so rare, and in order to ensure optimal treatment and survival for our patient, a computed tomography-guided biopsy was performed before en bloc tumour excision. Because of the possibility of malignancy, complete excision of the mass was performed, with pelvic blunt dissection. Histological examination showed a benign neoplasm, originating from the cells of peripheral nerve sheaths; the diagnosis was a schwannoma. Abdominal schwannomas are rare neoplasms that can be misdiagnosed. Laparoscopy is a safe and efficient option for approaching benign pelvic tumours and may offer the advantage of better visualisation of structures owing to the magnification in laparoscopic view, especially in narrow anatomical spaces. However, in our case laparoscopy was not considered owing to the size and anatomical location of the tumour.

Improved regeneration after femoral nerve injury in mice lacking functional T- and B-lymphocytes.

The immune system plays important functional roles in regeneration after injury to the mammalian central and peripheral nervous systems. After damage to the peripheral nerve several types of immune cells, invade the nerve within hours after the injury. To gain insights into the contribution of T- and B-lymphocytes to recovery from injury we used the mouse femoral nerve injury paradigm. RAG2-/- mice lacking mature T- and B-lymphocytes due to deletion of the recombination activating gene 2 were subjected to resection and surgical reconstruction of the femoral nerve, with the wild-type mice of the same inbred genetic background serving as controls. According to single frame motion analyses, RAG2-/- mice showed better motor recovery in comparison to control mice at four and eight weeks after injury. Retrograde tracing of regrown/sprouted axons of spinal motoneurons showed increased numbers of correctly projecting motoneurons in the lumbar spinal cord of RAG2-/- mice compared with controls. Whereas there was no difference in the motoneuron soma size between genotypes, RAG2-/- mice displayed fewer cholinergic and inhibitory synaptic terminals around somata of spinal motoneurons both prior to and after injury, compared with wild-type mice. Extent of myelination of regrown axons in the motor branch of the femoral nerve measured as g-ratio was more extensive in RAG2-/- than in control mice eight weeks after injury. We conclude that activated T- and B-lymphocytes restrict motor recovery after femoral nerve injury, associated with the increased survival of motoneurons and improved remyelination.

Management of medically intractable genitofemoral and ilioingunal neuralgia.

AIM: To evaluate the effectiveness of invasive procedures in medically intractable genitofemoral and ilioingunal neuralgia. MATERIAL AND METHODS: This is a prospective study of 20 patients with genitofemoral and ilioinguinal neuralgias who were treated at our medical center between 2007 and 2011. Genitofemoral and ilioinguinal nerve blocks were performed in all cases after medical treatment had failed to alleviate the patients' pain. Neurectomy was performed for the patients whose pain did not improve. Patient histories, physical examinations and visual analogue scale scores before and after treatments were analyzed. RESULTS: Fourteen (70%) of the patients were treated with nerve blocks and six (30%) of the patients whose pain did not improve with nerve block application underwent neurectomy which resulted in pain relief. CONCLUSION: For patients with medically intractable genitofemoral and ilioinguinal neuralgias, nerve blocks and neurectomies can be applied safely for pain control.

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.

Motor neuron target selectivity and survival after prolonged axotomy.

PURPOSE: After a cut peripheral nerve is repaired, motor neurons usually regenerate across the lesion site, however they often enter an inappropriate Schwann cell tube and may be directed to an inappropriate target organ such as skin, resulting in continued loss of function. In fact, only about 10% of adults who receive a peripheral nerve repair display full functional recovery. The reasons for this are many and complex, however one aspect is whether the motor neuron has undergone a prolonged period of axotomy prior to nerve repair. Previous studies have suggested a deleterious effect of prolonged axotomy. METHODS: We examined the influence of prolonged axotomy on target selectivity using a cross-reinnervation model of rat obturator motor neurons regrowing into the distal femoral nerve, with its normal bifurcating pathways to muscle and skin. RESULTS: Surprisingly, we found that a prolonged period of axotomy resulted in an increase in motor neuron regeneration accuracy. In addition, we found that regeneration accuracy could be increased even further by a simple surgical manipulation of the distal terminal nerve pathway to skin. CONCLUSIONS: These results suggest that under certain conditions prolonged axotomy may not be detrimental to the final accuracy of motor neuron regeneration and highlight that a simple manipulation of terminal nerve pathways may be one approach to increase such regeneration accuracy.

[Schwannoma of the femoral nerve: a rare differential diagnosis of leg pain]. / Das Schwannom des Nervus femoralis: Eine seltene Differenzialdiagnose bei Oberschenkelschmerzen.

BACKGROUND: Schwannomas (neurinomas) are among the most frequent peripheral nerve tumors. Nevertheless, these are seldom located in the lower extremities in association with the femoral nerve. CLINICAL PRESENTATION: In this case, the occurrence of a schwannoma adjacent to the femoral nerve is described in a patient presenting with nonspecific pain in the thigh accompanied by a palpable mass. Sensory and motor deficits were not present. Further examinations by MRI and biopsy followed by histopathology, revealed the diagnosis of a schwannoma. The tumor was completely excised. CONCLUSION: Although schwannomas of the lower extremities are rare, they should be included in the differential diagnosis. Knowing the typical clinical symptoms, radiological signs, and histopathological findings, diagnosis should be straight forward.

Dermatan 4-O-sulfotransferase1 ablation accelerates peripheral nerve regeneration.

Chondroitin sulfate (CS) and dermatan sulfate (DS) proteoglycans are major components of the extracellular matrix implicated in neural development, plasticity and regeneration. While it is accepted that CS are major inhibitors of neural regeneration, the contributions of DS to regeneration have not been assessed. To enable a novel approach in studies on DS versus CS roles during development and regeneration, we generated a mouse deficient in the dermatan 4-O-sulfotransferase1 (Chst14(-/-)), a key enzyme in the synthesis of iduronic acid-containing modules found in DS but not CS. In wild-type mice, Chst14 is expressed at high levels in the skin and in the nervous system, and is enriched in astrocytes and Schwann cells. Ablation of Chst14, and the assumed failure to produce DS, resulted in smaller body mass, reduced fertility, kinked tail and increased skin fragility compared with wild-type (Chst14(+/+)) littermates, but brain weight and gross anatomy were unaffected. Neurons and Schwann cells from Chst14(-/-) mice formed longer processes in vitro, and Chst14(-/-) Schwann cells proliferated more than Chst14(+/+) Schwann cells. After femoral nerve transection/suture, functional recovery and axonal regrowth in Chst14(-/-) mice were initially accelerated but the final outcome 3months after injury was not better than that in Chst14(+/+) littermates. These results suggest that while Chst14 and its enzymatic products might be of limited importance for neural development, they may contribute to the regeneration-restricting environment in the adult mammalian nervous system.

Saphenous neuropathy due to large hydatid cyst within long adductor muscle: case report and literature review.

An unusual case of saphenous neuropathy secondary to compression by a large hydatid cyst within the adductor longus muscle is reported. Solitary hydatid cyst(s) localized in the skeletal muscles occur rarely and often mimic soft tissue tumours. Presentation with signs of peripheral nerve compression by a hydatid cyst in an extremity is exceedingly rare. Diagnosis can be established by ultrasound, computerized tomography or magnetic resonance if clinically suspected. Clinical suspicion of hydatid origin of a solitary muscle cyst should be high especially in patients hailing from areas endemic for echinococcosis. Laboratory tests are usually unhelpful in such cases and needle biopsy carries the risk of anaphylactic shock and should therefore be avoided. Surgical removal of the unruptured cyst is the treatment of choice in cases of intramuscular hydatid cyst. In the present case, excision of the hydatid cyst was followed by complete clinical recovery. In the absence of systemic involvement, treatment with albendazole may be avoided.

[A forgotten eponym: the Mackiewicz sign].

In 1913, Dr. Jacob Mackiewicz, a Polish-Jewish neurologist, described a clinical sign (a maneuver) which indicates a femoral nerve injury or L4 root injury. He called it the "cruralis phenomenon", but in the German and Slavic literature, the sign is named after him: "the patient lies prone, the examiner lifts the thigh in one hand, with the other hand, bends the patient's knee slowly; this maneuver causes severe pain in the anterior part of the thigh and over the groin".

Obturator nerve transfer as an option for femoral nerve repair: case report.

OBJECTIVE: Nerve transfers have proved to be an important addition to the armamentarium in the repair of brachial plexus lesions, but have been used sparingly for lower extremity nerve repair. Here, we present what is believed to be the first description of a successful transfer of the obturator nerve to the femoral nerve. CLINICAL PRESENTATION: A 45-year-old woman presented with a complete femoral nerve lesion after removal of a large (15-cm) schwannoma of the retroperitoneum involving the lumbar plexus. INTERVENTION: The obturator nerve was transferred to the distal stump of the femoral nerve in the retroperitoneal space at the inguinal ligament three months post-injury. At 2 years post-repair, the patient demonstrated 4 out of 5 return (Medical Research Council grade) of quadriceps function and was able to walk nearly normally. CONCLUSION: In cases in which there are extensive gaps in the femoral nerve, transfer of the obturator nerve provides an option to traditional nerve graft repair.

Sensory axon targeting is increased by NGF gene therapy within the lesioned adult femoral nerve.

Even though peripheral nerves regenerate well, axons are often misrouted and reinnervate inappropriate distal pathways post-injury. Misrouting most likely occurs at branch points where regenerating axons make choices. Here, we show that the accuracy of sensory axon reinnervation is enhanced by overexpression of the guidance molecule nerve growth factor (NGF) distal to the bifurcation. We used the femoral nerve as a model, which contains both sensory and motor axons that intermingle in the parent trunk and distally segregate into the saphenous (SB) and motor branches (MB). Transection of the parent trunk resulted in misrouting of axon reinnervation to SB and MB. To enhance sensory axon targeting, recombinant adenovirus encoding NGF was injected along the SB close to the bifurcation 1 week post-injury. The accuracy of axon reinnervation was assessed by retrograde tracing at 3 or 8 weeks after nerve injury. NGF overexpression significantly increased the accuracy of SB axon reinnervation to the appropriate nerve branch, in a manner independent of enhancing axon regeneration. This novel finding provides in vivo evidence that gradient expression of neurotrophin can be used to enhance targeting of distal peripheral pathways to increase axon regeneration into the appropriate nerve branch.