An Unusual Cause of Femoral Nerve Paresis in a Horse: Disseminated B Cell Lymphoma With Plasmacytoid Differentiation and Direct Neuronal Invasion

A 21-year-old Quarter Horse mare presented with a chronic, progressively worsening left pelvic limb lameness of 3 weeks duration. The initial examination identified a consistent lameness at a walk. Neurological examination showed sensory and gait abnormalities consistent with left femoral nerve dysfunction. The horse minimally advanced the leg cranially and had a shortened stride length at the walk. During the stance phase, the heels of the left hind foot did not contact the ground and the horse quickly took weight off of the limb. Diagnostic imaging (ultrasound and nuclear scintigraphy) examinations did not reveal a cause. Severe lymphocytosis was identified on complete blood cell count (69,600 cells /uL; reference range: 1,500-4,000 cells/uL), suggestive of lymphoma. Postmortem examination revealed focal swelling of the left femoral nerve. Multiple masses were found in the stomach, large colon, adrenal gland, mesentery, heart, and meninges. The entire left pelvic limb was dissected and did not reveal other causes of the gait deficit. Histologic evaluation of the left femoral nerve revealed disseminated intermediate cell size B cell lymphoma, with an immunophenotype suggestive of plasmacytoid differentiation. These lymphocytes infiltrated the femoral nerve at the location of the focal nerve swelling, in addition to other peripheral nerves. This case highlights a horse with an atypical diagnosis of femoral nerve paresis caused by direct neoplastic lymphocyte infiltration, deriving from disseminated B cell lymphoma with plasmacytoid differentiation (neurolymphomatosis). Though rare, disseminated lymphoma with direct nerve infiltration should be considered in horses with peripheral neuropathies.

Prohibitin 1 is essential to preserve mitochondria and myelin integrity in Schwann cells

In peripheral nerves, Schwann cells form myelin and provide trophic support to axons. We previously showed that the mitochondrial protein prohibitin 2 can localize to the axon-Schwann-cell interface and is required for developmental myelination. Whether the homologous protein prohibitin 1 has a similar role, and whether prohibitins also play important roles in Schwann cell mitochondria is unknown. Here, we show that deletion of prohibitin 1 in Schwann cells minimally perturbs development, but later triggers a severe demyelinating peripheral neuropathy. Moreover, mitochondria are heavily affected by ablation of prohibitin 1 and demyelination occurs preferentially in cells with apparent mitochondrial loss. Furthermore, in response to mitochondrial damage, Schwann cells trigger the integrated stress response, but, contrary to what was previously suggested, this response is not detrimental in this context. These results identify a role for prohibitin 1 in myelin integrity and advance our understanding about the Schwann cell response to mitochondrial damage.

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.

Intraoperative neuromonitoring of anterior root muscle response during hip surgery under spinal anesthesia

The aim of this study was to evaluate the anterior root muscle (ARM) response monitorability during total hip arthroplasty (THA) under spinal anesthesia. A total of 20 adults (64.6 ± 13.87 years old) were monitored using ARM response and free-run electromyography during THA. To elicit the ARM response from muscles, percutaneous stimulation of the lumbosacral roots was performed by self-adhesive electrodes placed over the skin of the projection of the first and third lumbar interspinous space (anode) and over the abdominal skin of the umbilicus (cathode). Latency and amplitude values of the ARM response were recorded from both sides (non-operated and operated) and from five muscles as follows: rectus femoris (RF), vastus lateralis (VL), biceps femoris long-head (BF), Tibialis Anterior (TA) and gastrocnemius. The most recorded ARM response in a muscle was the TA (n = 38); the least recorded AMR response in a muscle was the BF (n = 33). The mean stimulus intensities for the non-operated and the operated sides were 462.5 ± 112.8 V and 520.0 ± 172.3 V (p = 0.834), respectively. The mean latencies and amplitude values of the ARM response from muscles were as follows: 8.8 ± 1.4 ms; 98.8 ± 114.5 µV for RF; 9.8 ± 2.1 ms; 119.1 ± 122.23 µV for VL; 9.5 ± 1.6 ms; 39.6 ± 30.3 µV for BF; 15.1 ± 1.9 ms; 146.6 ± 150.9 µV for TA; 15.6 ± 2.4 ms; 81.0 ± 99.9 µV for Gastrocnemius. The present study demonstrates that the ARM response could easily and safely be obtained during THA under spinal anesthesia. This non-invasive technique may have a potential to detect early neurological deficit in patients who need complex hip surgery under spinal anesthesia.

Research on the repairing effect of polylactic acid-trimethylene carbonate/GNDF slow-release catheter on the injured femoral nerve fiber

Present research aims to investigate the repairing effect of polylactic acid-trimethylene carbonate/GNDF slow-release catheter on the injured femoral nerve fiber. Adult SD male rats as the subjects were divided into two groups, the GDNF group and the control group, and received the surgery to remove the nerve from the exposed left femoral nerves. Thereafter, rats in the GNDF group and the control group received the GNDF or normal saline, and we evaluated the changes in rats, including the morphological, functional and electrophysiological changes of regenerated nerves. Regenerated axons were found in each group, but enormous regeneration of axons was only identified in GDNF group. Further analysis showed that: At the 4th, 8th and 12th weeks, areas of the regenerated nerves in GDNF group were (0.95±0.06) mm2, (1.14±0.07) mm2 and (1.22±0.06) mm2, respectively; in the control group, these were (0.15±0.01) mm2, (0.25±0.07) mm2 and (0.52±0.05) mm2, respectively. These showed that the outcome of GDNF group was superior to that of control group. In GDNF group, quantities of the myelinated fiber were (0.8119×104±0.0637×104), (1.3371×104±0.0460×104) and (1.7669×104±0.0542×104); while in control group, these were (0.2179×104±0.0097×104), (0.3490×104±0.0329×104) and (0.7737×l04±0.0788×104). Again, these results also indicated that the outcome of GDNF group was superior to that of the control group (p<0.05). In GDNF group, the average diameters of myelinated fibers were (2.25±0.17) μm, (2.42±0.14) μm and (2.80±0.10) μm, which were significantly better than (1.24±0.08) μm, (1.43±0.14) μm and (1.82±0.14) μm in the control group. Degrees of fiber myelination in the GDNF group were (0.71±0.03), (0.64±0.03) and (0.6l±0.0l), respectively, which were also significantly higher than (0.02±0.01), (0.04±0.01) and (0.06±0.02) in the control group (p<0.01). At the 12th week after surgery, HE staining was performed to observe the histological changes in quadriceps femoris for evaluation of atrophy in each group. In the GDNF group, significant amelioration was found in the atrophy of quadriceps femoris with an average area of myofiber of (84.95±3.92) %, while the area of the control group was (57.95±5.78) %, suggesting that the outcome of the GDNF group was better than that of the control group (p<0.05). Electrophysiological examination of nerves was employed to detect the recovery of neurological functions after repair of nerve defect. At the 4th, 8th and 12th weeks after surgery, CMAP amplitudes in the GDNF group were (9.34±0.52) mV, (14.40±0.69) mV and (19.18±0.48) mV, significantly better than (0.39±0.07) mV, (1.44±0.41) mV and (9.27±0.40) in the control group (p<0.01). Polylactic acid-trimethylene carbonate/GNDF slow-release catheter can accelerate the functional recovery of injured nerves, thus promoting the regeneration efficiency of femoral nerves.

Anatomic Variation in Patient with Lateral Femoral Cutaneous Nerve Entrapment Neuropathy

BACKGROUND

We report a surgical case of entrapment neuropathy of lateral femoral cutaneous nerve (LFCN) with anatomical variation.

CASE DESCRIPTION

This 53-year-old man had a 10-year history of paresthesia and pain in the right anterolateral thigh exacerbated by prolonged standing and walking. His symptoms improved completely but transiently by LFCN block. The diagnosis was LFCN entrapment. Because additional treatment with drugs and repeat LFCN block was ineffective, we performed surgical decompression under local anesthesia. A nerve stimulator located the LFCN 4.5 cm medial to the anterior superior iliac spine. It formed a sharp curve and was embedded in connective tissue. Proximal dissection showed it to run parallel to the femoral nerve at the level of the inguinal ligament. The inguinal ligament was partially released to complete dissection/release. Postoperatively, his symptoms improved and the numeric rating scale fell from 8 to 1.

CONCLUSION

We report a rare anatomical variation in the course of the LFCN.

Myelin Basic Protein Cleaves Cell Adhesion Molecule L1 and Improves Regeneration After Injury

Myelin basic protein (MBP) is a serine protease that cleaves neural cell adhesion molecule L1 and generates a transmembrane L1 fragment which facilitates L1-dependent functions in vitro, such as neurite outgrowth, neuronal cell migration and survival, myelination by Schwann cells as well as Schwann cell proliferation, migration, and process formation. Ablation and blocking of MBP or disruption of its proteolytic activity by mutation of a proteolytically active serine residue abolish L1-dependent cellular responses. In utero injection of adeno-associated virus encoding proteolytically active MBP into MBP-deficient shiverer mice normalizes differentiation, myelination, and synaptogenesis in the developing postnatal spinal cord, in contrast to proteolytically inactive MBP. Application of active MBP to the injured wild-type spinal cord and femoral nerve augments levels of a transmembrane L1 fragment, promotes remyelination, and improves functional recovery after injury. Application of MBP antibody impairs recovery. Virus-mediated expression of active MBP in the lesion site after spinal cord injury results in improved functional recovery, whereas injection of virus encoding proteolytically inactive MBP fails to do so. The present study provides evidence for a novel L1-mediated function of MBP in the developing spinal cord and in the injured adult mammalian nervous system that leads to enhanced recovery after acute trauma.

Non-Systemic Vasculitic Neuropathy: An Enigmatic Clinical Entity

BACKGROUND

Non-systemic vasculitic peripheral neuropathy is a rare condition characterized by necrotizing inflammation resulting in luminal narrowing of the vasa nervorum, leading to ischemic injury to peripheral nerves. Here, we present the case of 63-year-old woman with subacute onset of severe hyperesthesia of the lower extremities accompanied by foot drop.

CASE REPORT

A 63-year-old woman with prolonged history of uncontrolled diabetes mellitus presented with subacute onset of severe bilateral lower extremity hyperesthesia and motor weakness along with left-sided foot drop. She had multiple emergency room visits with no relief of her symptoms. High doses of analgesics were insufficient to control pain. Laboratory tests were positive only for high erythrocyte sedimentation rate and C-reactive protein. A skin biopsy obtained 5 cm above the left lateral malleolus revealed medium-sized dermal vasculitis with dense mononuclear infiltrate. Electromyography showed peripheral neuropathy. A nerve biopsy was needed to reveal the exact diagnosis.

CONCLUSIONS

Diagnosis of non-systemic vasculitic peripheral neuropathy can be delayed or missed in patients with uncontrolled diabetes mellitus, leading to significant morbidity. Elevated markers of inflammation in the absence of a possible explanation should prompt the clinician to perform a nerve biopsy; however, it is an invasive procedure and is associated with complications of post-neuropathic pain and delayed wound healing. Magnetic resonance angiography of the lower limbs, if combined with skin biopsy, can save the patient from undergoing nerve biopsy.

Motor evoked potentials for femoral nerve protection in transpsoas lateral access surgery of the spine

Detecting potential intraoperative injuries to the femoral nerve should be the main goal of neuromonitoring of lateral lumber interbody fusion (LLIF) procedures. We propose a theory and technique to utilize motor evoked potentials (MEPs) to protect the femoral nerve (a peripheral nerve), which is at risk in LLIF procedures. MEPs have been advocated and widely used for monitoring spinal cord function during surgical correction of spinal deformity and surgery of the cervical and thoracic spine, but have had limited acceptance for use in lumbar procedures. This is due to the theoretical possibility that MEP recordings may not be sensitive in detecting an injury to a single nerve root considering there is overlapping muscle innervation of adjacent root levels. However, in LLIF procedures, the surgeon is more likely to encounter lumbar plexus elements than nerve roots. Within the substance of the psoas muscle, the L2, L3, and L4 nerve roots combine in the lumbar plexus to form the trunk of the femoral nerve. At the point where the nerve roots become the trunk of the femoral nerve, there is no longer any alternative overlapping innervation to the quadriceps muscles. Insult to the fully formed femoral nerve, which completely blocks conduction in motor axons, should theoretically abolish all MEP responses to the quadriceps muscles. On multiple occasions over the past year, our neuro-monitoring groups have observed significantly degraded amplitudes of the femoral motor and/or sensory evoked potentials limited to only the surgical side. Most of these degraded response amplitudes rapidly returned to baseline values with a surgical intervention (i.e., prompt removal of surgical retraction).

Function-triggering antibodies to the adhesion molecule L1 enhance recovery after injury of the adult mouse femoral nerve

L1 is among the few adhesion molecules that favors repair after trauma in the adult central nervous system of vertebrates by promoting neuritogenesis and neuronal survival, among other beneficial features. In the peripheral nervous system, L1 is up-regulated in Schwann cells and regrowing axons after nerve damage, but the functional consequences of this expression remain unclear. Our previous study of L1-deficient mice in a femoral nerve injury model showed an unexpected improved functional recovery, attenuated motoneuronal cell death, and enhanced Schwann cell proliferation, being attributed to the persistent synthesis of neurotrophic factors. On the other hand, transgenic mice over-expressing L1 in neurons led to improved remyelination, but not improved functional recovery. The present study was undertaken to investigate whether the monoclonal L1 antibody 557 that triggers beneficial L1 functions in vitro would trigger these also in femoral nerve repair. We analyzed femoral nerve regeneration in C57BL/6J mice that received this antibody in a hydrogel filled conduit connecting the cut and sutured nerve before its bifurcation, leading to short-term release of antibody by diffusion. Video-based quantitative analysis of motor functions showed improved recovery when compared to mice treated with conduits containing PBS in the hydrogel scaffold, as a vehicle control. This improved recovery was associated with attenuated motoneuron loss, remyelination and improved precision of preferential motor reinnervation. We suggest that function-triggering L1 antibodies applied to the lesion site at the time of injury over a limited time period will not only be beneficial in peripheral, but also central nervous system regeneration.

Anatomical feasibility of performing a nerve transfer from the femoral branch to bilateral pelvic nerves in a cadaver: a potential method to restore bladder function following proximal spinal cord injury

OBJECT

Nerve transfers are an effective means of restoring control to paralyzed somatic muscle groups and have recently been shown to be effective in denervated detrusor muscle in a canine model. A cadaveric study was performed to examine the anatomical feasibility of transferring femoral muscular nerve branches to vesical branches of the pelvic nerve as a method of potentially restoring innervation to control the detrusor muscle in humans.

METHODS

Twenty cadavers were dissected bilaterally to expose pelvic and femoral muscular nerve branches. Ease of access and ability to transfer the nerves were assessed, as were nerve cross-sectional areas.

RESULTS

The pelvic nerve was accessed at the base of the bladder, inferior to the ureter, and accompanied by inferior vesical vessels. Muscular branches of the femoral nerve to the vastus medialis and intermedius muscles (L-3 and L-4 origins) were followed distally for 17.4 ± 0.8 cm. Two muscle branches were split from the femoral nerve trunk, and tunneled inferior to the inguinal ligament. One branch was moved medially toward the base of the bladder and linked to the ipsilateral pelvic nerve. The second branch was tunneled superior to the bladder and linked to the contralateral pelvic nerve. The cross-sectional area of the pelvic nerve vesical branch was 2.60 ± 0.169 mm(2) (mean ± SEM), and the femoral nerve branch at the suggested transection site was 4.40 ± 0.41 mm2.

CONCLUSIONS

Use of femoral nerve muscular branches from the vastus medialis and intermedius muscles for heterotopic nerve transfer of bilateral pelvic nerves is surgically feasible, based on anatomical location and cross-sectional areas.

Infrapatellar branch of saphenous neurectomy for painful neuroma: a case report

We present the case of an 18-year-old woman who was healthy other than a history of multiple arthroscopic right knee surgeries culminating in subtotal lateral meniscectomy in a valgus knee. The patient was referred to our office for evaluation for realignment osteotomy and meniscal transplantation. Her diagnosed case of neuroma of the infrapatellar branch of the saphenous nerve was managed with neurectomy, which produced prompt and complete resolution of pain.

Complications of femoral nerve block for total knee arthroplasty

Preemptive and multimodal pain control protocols have been introduced to enhance rehabilitation after total knee arthroplasty (TKA). We determined the complication rate associated with preoperative femoral nerve block (FNB) for TKA. Among 1018 TKA operations, we performed 709 FNBs using a single-injection technique into the femoral nerve sheath and confirming position with nerve stimulation before induction. After TKA, weightbearing as tolerated was initiated using a walker or crutches on postoperative Day 1. Twelve patients (1.6%) treated with FNB sustained falls, three (0.4%) of whom underwent reoperations. Five patients had postoperative femoral neuritis, which may have been secondary to the block. One patient had new onset of atrial fibrillation after FNB, and the TKA was postponed. Femoral nerve block before TKA is not a harmless intervention. We recommend postoperative protocols be modified for patients who have FNB to account for decreased quadriceps function in the early postoperative period, which can lead to falls.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

An accessory iliacus muscle: a case report

We present a case of an anomalous accessory iliacus muscle in the iliac fossa which gets originated from the iliac crest and inserting along with iliopsoas, and appear to compress the L4 root of femoral nerve. During the routine dissection of a male cadaver aged 58 years, we found an accessory iliacus muscle. The L2 and L3 nerve roots joined the L4 root distal to the accessory iliacus muscle. The L4 root of the femoral nerve supplied accessory iliacus muscle. Accessory iliacus muscle might cause tension on the femoral nerve resulting in referred pain to the hip and knee joints and to the lumbar dermatome L4. The clinical significance of this variant muscle and its importance in the femoral nerve entrapment has been discussed.

PROLONGED TARGET DEPRIVATION REDUCES THE CAPACITY OF INJURED MOTONEURONS TO REGENERATE

OBJECTIVE

To investigate whether or not it is the frustrated growth state (no axon growth) that reduces regenerative capacity or the inability of axotomized motoneurons to remake muscle connections (axon growth-no muscle contact) that accounts for poor regenerative capacity of chronically axotomized motoneurons.

METHODS

We chronically axotomized rat femoral motoneurons for 2 months by cutting the nerve and either capping the proximal nerve to prevent axon regeneration (Group 1, no axon growth for 2 mo) or encouraging axon regeneration but not target reinnervation by suture to the distal stump of cut saphenous nerve (Group 2, axon growth with no muscle contact). In the control fresh axotomy group (axon growth with muscle contact), femoral nerve stumps were resutured immediately. Two months later, the femoral nerve was recut and sutured immediately to encourage regeneration in a freshly cut saphenous nerve stump for 6 weeks. Regenerating axons in the saphenous nerve were back-labeled with fluorogold for enumeration of the femoral motoneurons that regenerated their axons into the distal nerve stump.

RESULTS

We found that significantly fewer chronically axotomized motoneurons regenerated their axons than freshly axotomized motoneurons that regenerated their axons to reform nerve-muscle connections in the same length of time. The number of motoneurons that regenerated their axons was reduced in both the conditions of no axon growth and axon growth with no muscle contact; thus chronic axotomy for a 2-month period reduced regenerative success irrespective of whether the motoneurons were prevented from regenerating or encouraged to regenerate their axons in that same period of time.

CONCLUSION

Axonal regeneration does not protect motoneurons from the negative effects of prolonged axotomy on regenerative capacity. It is the period of chronic axotomy, in which motoneurons remain without target nerve-muscle connection, and not simply a state of frustrated growth that accounts for the reduced regenerative capacity of those neurons.

Motor neuron regeneration accuracy: balancing trophic influences between pathways and end-organs

The key to recovery of function following peripheral nerve lesions is guiding axons back to their original target end-organs. The parent femoral nerve splits into two comparable terminal pathways: one to the muscle and the other to the skin. Normally, motor neurons only innervate the pathway to the muscle, but after the parent nerve is repaired regenerating motor neurons are often misrouted to the skin. When the muscle and skin pathways remain connected to their respective targets after the parent nerve is repaired, reinnervation favors the muscle pathway. If contact with the muscle is instead prevented, reinnervation favors the pathway to the skin. Here we examine whether shortening the skin pathway can alter motor reinnervation accuracy when the muscle pathway remains connected to the muscle. We demonstrate that reducing the influence of the skin pathway results in a more rapid and extensive reinnervation of the muscle pathway. These findings suggest that the relative balance of trophic influences from the pathways and their end-organs is an important determinant of motor neuron regeneration accuracy, and that the muscle pathway by itself is not the primary regulator for regeneration accuracy of motor neurons.

Femoral nerve entrapment: A new insight

Compression of the femoral nerve in the iliac fossa has been reported as a consequence of several pathologies, but never as a result of muscular compression. Aberrant slips of iliacus, however, have occasionally been reported to cover or split the femoral nerve. This study aimed to assess such variations as potential factors in femoral nerve compression. A large and homogeneous sample of 121 embalmed cadavers (242 specimens) was studied. Statistical comparisons were made using the chi-squared test. Muscular slips from iliacus and psoas, piercing or covering the femoral nerve, were found in 19 specimens (7.9%). No significant differences by sex or side were found. The more frequent variation was piercing of the femoral nerve by a muscular slip (17 specimens, 7.0%). The nerve then entered the thigh as one or more branches. The less frequent variation found was a muscular slip or sheet covering the femoral nerve as it lay on iliacus (2 specimens, 0.8%). Each disposition may be a potential risk for nerve entrapment.

The pharmacodynamics of ropivacaine and bupivacaine in combined sciatic and femoral nerve blocks for total knee arthroplasty

The potency of ropivacaine compared with bupivacaine in regional anesthesia remains controversial. Therefore, we compared the pharmacodynamics of equal concentrations of bupivacaine and ropivacaine in combined sciatic and femoral nerve blocks for patients undergoing knee arthroplasty. Fifty patients received 40 mL of either 0.5% bupivacaine (n = 25) or 0.5% ropivacaine (n = 25) divided between the sciatic (15 mL) and the femoral (25 mL) nerves before induction of anesthesia. Loss and recovery of sensory (% of cold sensation compared to opposite side) and motor (no contraction or normal muscle force) functions were recorded in the distribution of the femoral, saphenous, common peroneal, and tibial nerves. Pain scores and morphine consumption over 48 h were also evaluated. There were no difference between bupivacaine and ropivacaine in terms of onset of sensory and motor blockade. However, resolution of sensory and motor function was faster in the ropivacaine group but only significantly so for the sciatic nerve and between 24 to 28 h for sensory resolution and 12 to 20 h for motor function. Overall, pain scores and morphine consumption were similar. In conclusion, we showed that block resolution is different between bupivacaine and ropivacaine when administered for combined sciatic and femoral nerve blocks. A new systematic method to assess sciatic and femoral nerve blockade is proposed.

The psoas quartus muscle

We report an unusual finding in an adult male cadaver. During the routine dissection of the posterior abdominal wall as part of an anatomy course at our institution, an anomalous muscle was noted. This muscle originated from the transverse process of the left L3 vertebrae and the medial aspect of the quadratus lumborum. We believe this muscle to represent a variety of the psoas quartus that, to our knowledge, has only been described once before in the extant medical literature. The presence of a psoas quartus muscle may contribute to femoral nerve compression. The clinician may wish to consider this rare muscular anomaly in patients with symptoms of femoral nerve compression in which no other clear etiology is found. Furthermore, clinicians who image the posterior abdominal wall should be aware of this potential anomaly when interpreting the anatomy of this region.

Bilateral femoral neuropathy associated with disseminated intravascular coagulopathy: a case report

We report a case of 20-year-old man who presented with bilateral femoral nerve palsy following resuscitation for traumatic massive blood loss and its consequence. A high suspicious index for this complication may lead to its early recognition. Its related pathoanatomy is discussed based on the described evidences in the literature. Nonoperative treatment remains as a recommended option for coagulopathy-related neuropathy.

Transgenic expression of human connexin32 in myelinating Schwann cells prevents demyelination in connexin32-null mice

Mutations in Gap Junction beta1 (GJB1), the gene encoding the gap junction protein connexin32 (Cx32), cause the X-linked form of Charcot-Marie-Tooth disease (CMT1X), an inherited demyelinating neuropathy. We investigated the possibility that the expression of mutant Cx32 in other cells besides myelinating Schwann cells contributes to the development of demyelination. Human Cx32 was expressed in transgenic mice using a rat myelin protein zero (Mpz) promoter, which is exclusively expressed by myelinating Schwann cells. Male mice expressing the human transgene were crossed with female Gjb1/cx32-null mice; the resulting male offspring were all cx32-null (on the X chromosome), and one-half were transgene positive. In these transgenic mice, all of the Cx32 was derived from the expression of the transgene and was found in the sciatic nerve but not in the spinal cord or the liver. Furthermore, the Cx32 protein was properly localized (within incisures and paranodes) in myelinating Schwann cells. Finally, the expression of human Cx32 protein "rescued" the phenotype of cx32-null mice, because the transgenic mice have significantly fewer demyelinated or remyelinated axons than their nontransgenic littermates. These results indicate that the loss of Schwann-cell-autonomous expression of Cx32 is sufficient to account for demyelination in CMT1X.

Advanced glycation endproducts in peripheral nerve in type 2 diabetes with neuropathy

Advanced glycation endproducts (AGE) accumulate over proteins as a consequence of diabetic hyperglycemia, and thus contribute to the pathogenesis of diabetic complications. To improve the understanding of the pathology of diabetic neuropathy, AGE accumulation was analyzed in sural and/or femoral nerves obtained under spinal anesthesia from 8 type 2 diabetic patients with both distal symmetrical polyneuropathy and proximal neuropathy. Pronounced AGE immunoreactivity was detected on axons and myelin sheaths in 90% of diabetic peripheral nerves but not in the control specimen. The intensity of axonal AGE immunopositivity significantly correlated with the severity of morphological alterations (p<0.005). AGE localization, demonstrated by immunohistochemical methods, was also present in the endoneurium, perineurium and microvessels. Morphometric analysis of the diabetic peripheral nerve showed perineurial thickening (diabetic vs. control, 15.5+/-4.9 vs. 6.6+/-2.1 microm, p<0.001), narrowing of the microvessel lumina (66.6+/-50.5 vs. 579.5+/-38.4 x10(3) microm(2), p<0.001) and significant reduction in the number of preserved axons (3.6+/-3 vs. 8.9+/-2.3 per 10(5) microm(2) per area, p<0.037). The sera of diabetic patients contained epitope(s) of AGE structure and soluble immune complexes containing AGE moiety. In conclusion, to the best of our knowledge, this is the first study providing evidence for excessive AGE formation on peripheral nerve components, primarily axons, and a significantly higher level of circulating AGE-immune complexes in patients with both distal diabetic polyneuropathy and proximal neuropathy. Humoral immune mechanisms, including the production of anti-AGE autoantibody, may potentially be involved in the development of structural abnormalities described in this report.

[Mild type of hemophilic pseudotumor with injury of femoral nerve (one case report)]

To explore the diagnoses and treatment of hemophilic pseudotumor, one case with hemophilic pseudotumor misdiagnosed and treated by operation, was observed and analyzed. The result showed that the final diagnosis of this case was following: hemophilia A (mild type) and hemophilic pseudotumor with injury of femoral nerve. The final diagnosis was given from inquiring case history and family history additionally, and drawing assistance from laboratory examination and computed tomography. After operation, the patient's wound healed very well through supplying coagulation factors positively. In conclusion, it was important for inquiring case history and family history particularly and thinking highly of laboratory examination to reduce the misdiagnosis and error of therapy for this case. If paying attention to preoperative preparation, the danger of hemorrhage during operation can be reduced and wound after operation can heal more rapidly.

Intrapelvic and thigh-level femoral nerve lesions: management and outcomes in 119 surgically treated cases

OBJECT

The authors present a retrospective analysis of 119 surgically treated femoral nerve lesions at intrapelvic and thigh levels seen at the Louisiana State University Health Sciences Center.

METHODS

Femoral nerve lesions treated between 1967 and 2000, (89 traumatic injuries and 30 tumors and cystic lesions) were evaluated for injury mechanisms, resulting lesions, surgical management, and postoperative functional outcomes by using retrospective chart reviews. The most common injury mechanism was iatrogenic (52 cases), which occurred after hernia and hip operations (10 each), followed by arterial bypass and gynecological procedures (eight each), angiography (seven), abdominal surgery (five), appendectomy (two), a laparoscopy, and a lumbar sympathectomy. Other injury mechanisms included hip or pelvic fractures (19), gunshot wounds (10), and lacerations (eight). The 30 femoral nerve tumors and cystic lesions consisted of neurofibromas (16), schwannomas (nine), ganglionic cysts (two), neurogenic sarcomas (two), and a leiomyosarcoma. Forty-four patients underwent neurolysis. Some had recordable nerve action potentials (NAPs) across their lesions in continuity, despite severe distal loss. Others with recordable NAPs had mild loss, but also experienced a pain problem, which was helped in some by neurolysis. In 36 patients, in whom repairs were performed using long sural grafts for mostly proximal pelvic-level injuries, recovery of useful function occurred. Eight of nine thigh-level suture repairs led to improvement to good functional levels. Most of the tumors and cystic lesions were resected, with preservation of preoperative function.

CONCLUSIONS

The majority of femoral nerve injuries resulted in lesions in continuity, and intraoperative NAP recordings were essential in evaluating axonal regeneration across these lesions. Despite severe and frequently proximal injury levels requiring repairs with long grafts, femoral nerve lesion repairs resulted in good functional recovery.

Lateral femoral cutaneous neuralgia: an anatomical insight

A detailed anatomic study was carried out on the lateral femoral cutaneous nerve to better understand the etiology and treatment of lateral femoral cutaneous neuralgia. As it passed from the pelvis into the thigh, the lateral femoral cutaneous nerve ran through an "aponeuroticofascial tunnel," beginning at the iliopubic tract and ending at the inguinal ligament; as it passed through the tunnel, an enlargement in its side-to-side diameter was observed, suggesting that the fascial structures proximal to the inguinal ligament may be implicated in the genesis of lateral femoral cutaneous neuralgia. The finding of pseudoneuromas at this location, distant from the inguinal ligament, supports this hypothesis. The anterior superior iliac spine is located approximately 0.7 cm from the lateral femoral cutaneous nerve and serves as the bony landmark for nerve localization. Within the first 3 cm of leaving the pelvis, the lateral femoral cutaneous nerve was observed deep to the fascia lata; therefore, surgical dissection within the subcutaneous fascia may be conducted with relative impunity near the anterior superior iliac spine just inferior to the inguinal ligament. In 36% of cases there was no posterior branch of the nerve, which is correlated to lateral femoral cutaneous neuralgia symptoms often being limited to the anterior branch region. An accessory nerve was found in 30% of cases.

Effect of lithotomy positions on strain of the obturator and lateral femoral cutaneous nerves

The purpose of this study was to determine if various lithotomy positions increase strain on the obturator and lateral femoral cutaneous nerves in fresh adult cadavers. A static load cell was used to record strain changes of the obturator and lateral femoral cutaneous nerves in the pelvis and anterior thigh when the lower limbs were placed in three sets of positions of varying hip abduction and flexion. The means of the strain measurements, which were measured in grams in all positioning angles were compared to the baseline 0 degrees measurements. Analysis of variance was calculated for the differences. Flexion of the hip did not increase strain on either nerve. Abduction to 30 degrees or 45 degrees increased strain by more than 30 g on the obturator nerve (P < 0.05) but not the lateral femoral cutaneous nerve. The addition of 45 degrees or more of flexion to abduction negated the strain increase on the obturator nerves seen with abduction alone. Nerve strain >30 g has been associated consistently with nerve dysfunction, disrupting axonal transmission, and causing structural neural damage. Our findings suggest that concomitant hip flexion should be used when placing anesthetized patients in a lithotomy position that includes abduction of the lower limbs to >30 degrees to decrease the risk for perioperative neuropathy of the obturator nerve.

[Extensive multinodular schwannoma of femoral nerve]

HISTORY AND PHYSICAL EXAMINATION

A 34-year-old woman contacted her general practitioner due to increasing circumference of her right thigh combined with occasional pain. The physical examination showed multiple nodular masses both in the groin and along the thigh that were painful to touch. The remainder of the physical examination was unremarkable.

DIAGNOSIS, THERAPY, AND CLINICAL COURSE

Both on ultrasonography and magnetic resonance imaging (MRI) a nodular mass was found on the right thigh extending from the groin to the inner side of the knee. A tissue biopsy with histological reviewing led to the diagnosis of a benign schwannoma. The following operation and clinical course went without major complications.

CONCLUSION

Peripheral schwannomas are rare, benign tumors of the nerve sheath usually appearing as round or oval masses. A schwannoma along the femoral nerve with an atypical shape of small diameter and an extension over a few decimeters has not been recorded yet. In spite of the length it is possible to treat schwannomas surgically without serious, permanent damage to the involved nerve.

Pediatric meralgia paresthetica

Meralgia paresthetica is a focal peripheral neuropathy involving the lateral femoral cutaneous nerve and is rarely observed in pediatric practice. Previous reports have highlighted its occurrence within the context of a regional bony malignancy. We present here three patients less than 18 years of age with idiopathic meralgia paresthetica.

Morphometric analysis of the human femoral nerve and its ageing process

We analysed the sizes of nerve fibres in the human femoral nerve which innervates the quadriceps femoris muscles. The material was taken from 14 cadavers aged from 61 to 97 years. A linear regression analysis disclosed a significant age-related decrease of the mean transverse area of axons. Such decrease with age may be an indication of motoneuron atrophy. Our results could help in the understanding of the correlation between morphology and function during the ageing process.

Secondary amyloidosis as a life-ending event in multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is a disorder of peripheral nerve often associated with a high monosialoganglioside (GM1) antibody and multifocal conduction block. It has a chronic, indolent course with involvement of predominantly peripheral motor nerves, usually in an asymmetric fashion. There have been few reported cases of progression to frank quadriplegia. Secondary amyloidosis refers to the deposition of amyloid in various tissues due to an underlying chronic inflammatory state. We report the first case, to our knowledge, of a patient with MMN associated with high titer of GM1 antibody who developed acute paraplegia with both cranial nerve and worsening sensory involvement associated with multiorgan compromise due to a secondary amyloidosis involving the myocardium.

Inflammation with no axonal damage of the rat saphenous nerve trunk induces ectopic discharge and mechanosensitivity in myelinated axons

Inflammation along a nerve trunk with no frank axonal nerve damage produced by complete Freund's adjuvant (CFA) or Carrageenan is known to induce a painful peripheral neuropathy. In the present study, we examined the electrophysiological properties of myelinated axons (spontaneous discharge and mechanical sensitivity) at the inflamed nerve site. The rat saphenous nerves were exposed at mid-thigh level and wrapped in 2 mm wide bands of haemostatic oxidized cellulose (Oxycel) that were saturated with undiluted CFA. In the control rats the Oxycel) was saturated with saline. At postoperative days (PODs) 2-5 and 6-10, fine axon bundles were teased from the nerve, and electrophysiological recordings performed. At both time points spontaneous activity at the site of the application in CFA rats (PODs 2-5=9.9+/-2.5%: PODs 6-10=6.1+/-1.4%) was significantly higher than in the control animals (PODs 2-5=2.9+/-1.1%: PODs 6-10=1.6+/-1.4%: P=0.03, P=0.02, respectively). Mechanical sensitivity at both time points was significantly higher in CFA rats (PODs 2-5=12.6+/-3.1%: PODs 6-10=10.3+/-3.1%) than in saline rats (PODs 2-5=3.4+/-2.91%: PODs 6-10=0.8+/-1.0%: P=0.03, P=0.04, respectively). This study clearly shows that perineural inflammation with no axonal nerve damage induced by CFA application around the nerve trunk elevates spontaneous activity and induces mechanosensitivity in myelinated axons.

Use of enhanced stimulation voltage to determine the severity of compressive peripheral nerve injury

BACKGROUND

The aim of this study was to investigate whether enhanced stimulation voltage could be a predictor of the extent of injury in acute compressive peripheral nerve trauma.

METHODS

The femoral nerves were exposed on both sides, in 11 anesthetized rabbits. Supramaximal stimulation voltage was used to produce a maximal-amplitude compound muscle action potential (CMAP) from the quadriceps femoris muscle. Afterward, the left femoral nerve was clipped for 1 minute, and the right femoral nerve for 5 minutes to produce an acute compressive injury. Immediately after removal of the clip, the proximal and distal sides of the clippage site were stimulated by gradually increased voltage until CMAPs were obtained. The same procedure was repeated at the 30th and 60th minutes. The ratio of the CMAP amplitudes obtained from proximal and distal stimulation was measured to establish a classification.

RESULTS

The stimulation voltages and amplitudes of the CMAPs before clippage were similar with the after-clippage values obtained from distal stimulation (p > 0.05), but the after-clippage values obtained from proximal stimulation were different in both sides (p < 0.05). Doubled stimulation voltage was enough to obtain CMAPs on the left side, but eightfold the initial level was required on the right side. The amplitude ratios recovered to preinjury levels in all of the subjects on the left side, but only two showed recovery on the right side (p < 0.001). Histopathologically, there was axonal compression without discontinuity on the left side, whereas the fibers were dispersed on the right side.

CONCLUSION

Stimulation voltage was found to discriminate the severity of the lesion in experimental peripheral nerve injury. Proximal to distal amplitude ratio seems to be a prognostic factor when the injury is less severe.

Metastatic cardiac myxoma

A 22-year-old woman who had a history of three cardiac operations and a bilateral femoral embolectomy for recurrent cardiac myxoma and myxoma embolism, respectively, was accepted to our clinic with multiple immobile peripheral masses. One of them was compressing the left common femoral artery. This mass was extirpated. Pathology examination revealed myxoma. Chemotherapy was given to the patient and regression of the masses was observed.

Intercostal nerve neurotization of the femoral nerve in patients with paraplegia--an anatomical feasibility study

Neurotization of the brachial plexus is an established procedure in the upper limb. However, neurotization of the lower limb remains experimental. Brunelli reported the use of the ulnar nerve to neurotize the lower limb. Zhao et al reported the use of intercostals nerve to neurotize the lower limb in rats. The aim of the study was to determine the feasibility of using intercostals nerve to neurotize the femoral nerve in human cadavers and to ascertain the ideal intercostals nerve that has the anatomical course that suit this role. Six fresh cadaveric dissection were performed through an extensile midline incision in the postmortem room and the lower six (T7-T12) were identified and traced from their origin. Their length and course identified and charted. T9 and T10 intercostal nerve was thought to be the most suitable nerve as the donor nerve, and the T11 and T12 intercostal nerve could not be free from its intra-muscular course sufficiently to be use as donor.

Iliopsoas hematoma with femoral neuropathy presenting a diagnostic dilemma after spinal decompression

STUDY DESIGN

Case report of an iliopsoas hematoma with femoral neuropathy appearing 8 weeks after a posterior spinal decompression procedure.

OBJECTIVES

To describe a potential complication and differential diagnosis for nerve root symptoms following spinal decompression.

SUMMARY OF BACKGROUND DATA

Iliopsoas hematoma is usually a complication of anticoagulation, hemophilia, or trauma. It has not been described previously as a complication of posterior spinal decompression. Femoral neuropathy results from compression within the iliopsoas compartment.

METHODS

A 53-year-old woman reported pain in the right side of her groin and an increasing fixed flexion deformity of the right hip 8 weeks after a posterior, midline, spinal decompression. A femoral neuropathy later developed. Magnetic resonance imaging and computed tomography were performed.

RESULTS

Imaging studies demonstrated a diffusely enlarged iliopsoas. Exploration revealed a large hematoma, which was evacuated. The compartment was fully decompressed with resolution of the nerve root symptoms within 48 hours.

CONCLUSIONS

Iliopsoas pathology is a rare cause of nerve root symptoms and presented diagnostic difficulties after an apparently successful spinal decompression.

Malignant peripheral nerve sheath tumors in the setting of segmental neurofibromatosis. Case report

Approximately 100 cases of segmental neurofibromatosis (NF5) have been reported in the recent literature. Patients with NF5 present with café-au-lait macules, freckles, and/or neurofibromas limited to one or adjacent dermatomes. Neurofibromas arising in NF5 have been uniformly considered to be benign; patients were thought to have an excellent prognosis without the risk of developing malignant peripheral nerve sheath tumors (PNSTs), which are characteristic in patients with the generalized form of this disease, von Recklinghausen's NF. In this report the authors detail the first observations of malignant PNSTs in two patients with NF5. Indications for surgical removal of a neurofibroma in a patient with NF include pain. neurological impairment, compression of adjacent structures, cosmetic disfigurement, and rapid tumor growth suggestive of malignant degeneration. Surgical indications are similar for patients with NF5. All patients with neurofibromas should be considered at risk for malignant degeneration.

Iliopsoas haemophiliac pseudotumours with bowel fistulation

Two cases of iliopsoas haemophilic pseudotumours are presented. In one patient a fistula developed between a pseudotumour and the large bowel. This resulted in an abscess involving the pseudotumour and adjacent tissues. It resolved after 5 years of therapy involving percutaneous drainage and closure of the fistula. The second patient had a massive pseudotumour that had obstructed both ureters. Later he suffered a fatal mixed Gram negative septicaemia probably related to erosion into the colon.

Mechanoreceptors in collateral knee ligaments: an animal experiment

The mechanoreceptors in the collateral ligaments of the knee joint in rat hindlimbs were studied. In group II (n=10) the femoral and obturator nerves were sectioned. In both groups III and V (n=20) the sciatic nerve was sectioned. In group V (n=10) the sectioned sciatic nerve was sutured 4 weeks after sectioning. In group IV (n=10) all three nerves were sectioned. Group I (n=10) served as control. After 4 months all animals were killed. The ligaments of the knee joint were preserved and stained with gold chloride, paraffin-embedded and cut in sagittal serial sections. The results showed that 4 months after partial or total denervation of the limb, there was necrosis and a decrease in the number of mechanoreceptors, which was dependent upon the severity and site of the lesion. After suture of the sciatic nerve the increase in mechanoreceptors suggested a regenerative process.

Loss of distal axons and sensory Merkel cells and features indicative of muscle denervation in hindlimbs of P0-deficient mice

Mice lacking the major Schwann cell myelin component P0 show a severe dysmyelination with pathological features reminiscent of the Déjérine-Sottas syndrome in humans. Previous morphological and electrophysiological studies on these mice did not only demonstrate a compromised myelination and myelin maintenance, but were suggestive of an impairment of axons as well. Here, we studied the axonal pathology in P0-deficient mice by quantitative electron microscopy. In addition, we investigated epidermal receptor end organs by immunocytochemistry and muscle pathology by histochemistry. In proximal sections of facial and femoral nerves, axon calibers were significantly reduced, whereas the number of myelin-competent axons was not diminished in 5- and 17-month-old P0-deficient mice. However, in distal branches of the femoral and sciatic nerve (digital nerves innervating the skin of the first toe) the numbers of myelin-competent axons were reduced by 70% in 6-month-old P0-deficient mice. Immunolabeling of foot pads revealed a corresponding loss of Merkel cells by 75%, suggesting that survival of these cells is dependent on the presence or maintenance of their innervating myelinated axons. In addition, quadriceps and gastrocnemius muscles showed pathological features indicative of denervation and axonal sprouting. These findings demonstrate that loss of an important myelin component can initiate degenerative mechanisms not only in the Schwann cell but also in the distal portions of myelinated axons, leading to the degeneration of specialized receptor end organs and impairment of muscle innervation.

Studies in transgenic mice indicate a loss of connexin32 function in X-linked Charcot-Marie-Tooth disease

X-linked Charcot-Marie-Tooth disease (CMTX) is an inherited demyelinating neuropathy caused by mutations in the gene encoding the gap junction protein connexin32 (Cx32). Despite the identification of over 160 different mutations in the Cx32 coding sequence, it is not known whether the mutations cause the disease manifestations through a loss of Cx32 function or through toxic effects on peripheral nerve. We created transgenic mice with a frameshift mutation at codon 175 (175fs), identified in a large CMTX pedigree. Light microscopic examination of the peripheral nerves from adult transgenic animals showed no pathological features. Western blotting did not show transgenic Cx32 protein in any of the 26 lines, although expression of transgenic messenger RNA was detected by reverse-transcriptase polymerase chain reaction and by ribonuclease protection assay. Our findings indicate that the 175fs mutation results in a loss of Cx32 function, without additional toxic effects.

Motor neuropathy in porphobilinogen deaminase-deficient mice imitates the peripheral neuropathy of human acute porphyria

Acute porphyrias are inherited disorders caused by partial deficiency of specific heme biosynthesis enzymes. Clinically, porphyrias are manifested by a neuropsychiatric syndrome that includes peripheral neuropathy. Although much is known about the porphyrias' enzyme defects and their biochemical consequences, the cause of the neurological manifestations remains unresolved. We have studied porphyric neuropathy in mice with a partial deficiency of porphobilinogen deaminase (PBGD). PBGD-deficient mice (PBGD-/-) imitate acute porphyria through massive induction of hepatic delta-aminolevulinic acid synthase by drugs such as phenobarbital. Here we show that PBGD-/- mice develop impairment of motor coordination and muscle weakness. Histologically femoral nerves of PBGD-/- mice exhibit a marked decrease in large-caliber (>8 microm) axons and ultrastructural changes consistent with primary motor axon degeneration, secondary Schwann cell reactions, and axonal regeneration. These findings resemble those found in studies of affected nerves of patients with acute porphyria and thus provide strong evidence that PBGD deficiency causes degeneration of motor axons without signs of primary demyelination, thereby resolving a long-standing controversy. Interestingly, the neuropathy in PBGD-/- mice developed chronically and progressively and in the presence of normal or only slightly (twofold) increased plasma and urinary levels of the putative neurotoxic heme precursor delta-aminolevulinic acid. These data suggest that heme deficiency and consequent dysfunction of hemeproteins can cause porphyric neuropathy.

Localized hypertrophic mononeuropathy involving the femoral nerve

The authors report a case of localized hypertrophic mononeuropathy involving the femoral nerve in a 20-year-old woman referred because of progressive weakness and atrophy of the left thigh. MRI showed an enlarged femoral nerve and biopsies of fascicles displayed a concentric pattern of cells resembling an onion bulb. These cells were positive for epithelial membrane antigen immunostaining and had an incomplete basal lamina.

Localized hypertrophic neuropathy: magnetic resonance imaging findings and long-term follow-up

Four patients with painless, progressive focal neurological deficits that localized to peripheral nerve or plexus were eventually found to have the relatively rare condition of localized hypertrophic neuropathy or intraneural perineurioma. Magnetic resonance imaging (MRI) was an excellent tool for aiding in the precise localization of the lesion, if specifically tailored with regard to imaging planes and specific MRI sequences. Fat-saturated T2-weighted and fat-saturated T1-weighted postgadolinium images provided the best visualization, particularly with a high-field magnet and phase array body coil. Two patients stabilized following resection of the lesion and sural nerve grafting, and 1 had partial improvement in a proximal muscle following neurolysis.