Proximal sensory neuropathies of the Leg

Origin, course, and distribution of the posterior femoral cutaneous nerve and the spatial relationship among its branches

This study aimed to elucidate the origin, course, and distribution of the branches of the posterior femoral cutaneous nerve, considering the segmental and dorsoventral compositions of the sacral plexus, including the pudendal nerve. The buttocks and thighs of five cadavers were analyzed bilaterally. The branches emerged from the sacral plexus, which was divided dorsally to ventrally into the superior gluteal, inferior gluteal, common peroneal, tibial, and pudendal nerves. It descended lateral to the ischial tuberosity and comprised the thigh, gluteal, and perineal branches. As for the thigh and gluteal branches, the dorsoventral order of those originating from the sacral plexus corresponded to the lateromedial order of their distribution. However, the dorsoventral boundary was displaced at the inferior margin of the gluteus maximus between the thigh and gluteal branches. The perineal branch originated from the ventral branch of the nerve roots. In addition, the pudendal nerve branches, which ran medially to the ischial tuberosity, were distributed in the medial part of the inferior gluteal region. These branches should be distinguished from the gluteal branches; the former should be classified as the medial inferior cluneal nerves and the latter as the lateral ones. Finally, the medial part of the inferior gluteal region was distributed by branches of the dorsal sacral rami, which may correspond to the medial cluneal nerves. Thus, the composition of the posterior femoral cutaneous nerve is considered necessary when considering the dorsoventral relationships of the sacral plexus and boundaries of the dorsal and ventral rami.

Simultaneous Posterior Femoral Cutaneous Nerve and Sciatic Nerve Variations: A Case Report

During the routine dissection of a formalin fixed Caucasian cadaver, a previously unreported variation of the sacral plexus was found in the right gluteal region. The posterior femoral cutaneous nerve was found to pierce the piriformis muscle as opposed to running along its more common course below the muscle. At the same level of the posterior femoral cutaneous nerve, the common fibular nerve also pierced the piriformis muscle, while the tibial nerve passed inferior to the piriformis muscle. No other anatomical variations were found.

Posterior femoral cutaneous neuropathy in piriformis syndrome: A vascular hypothesis

Piriformis syndrome is described as a neuromuscular condition which occurs when the sciatic nerve is compressed and/or irritated by the piriformis muscle. It is characterized by acute tenderness in the buttock with sciatica-like pain radiating into the posterior aspect of the thigh, leg, and foot. The neurogenic leg and foot pain experienced with this condition is consistent with involvement of the sciatic nerve. However, the posterior thigh pain associated with piriformis syndrome is due to involvement of the posterior femoral cutaneous nerve (i.e., posterior cutaneous nerve of the thigh), which is a branch of the sacral plexus independent of the sciatic nerve. This nerve is rarely mentioned relative to piriformis syndrome even though posterior thigh pain is more prevalent in patients than leg and foot pain. In the few instances when the posterior femoral cutaneous nerve is referenced relative to piriformis syndrome the neuralgic signs associated with it are attributed to compression by piriformis. Yet, given the dramatic size difference between the sciatic and posterior femoral cutaneous nerves one would expect direct piriformis compression to impact the sciatic nerve first and produce leg/foot pain at a far greater frequency than posterior thigh pain. However, the opposite is seen in the literature, which raises the question, what underlying mechanism is responsible for this phenomenon? It is hypothesized that the prevalence of posterior femoral cutaneous nerve involvement in piriformis syndrome is due to compression of the inferior gluteal vein by a hypertrophied piriformis muscle.

Natural history of lateral femoral cutaneous nerve neuropraxia after anterior approach total hip arthroplasty

AIM:

The aim of this study was to examine the natural history of lateral femoral cutaneous nerve (LFCN) neuropraxia in a previously reported cohort of individuals after direct anterior approach (DAA).

METHODS:

99 patients (107 hips) with LFCN neuropraxia were identified, out of which 82 patients (87 hips) (83.1%) completed functional outcomes questionnaires at mean follow-up of 5.5 years (4.4-6.9 years). 5 patients were excluded from the study due to intra-articular source of pain and/or revision surgery. The total sample was composed of 77 patients (31 total hip replacements and 51 hip resurfacings) and functional outcomes scores were obtained for all patients.

RESULTS:

At average 5.46-year follow-up, 55 patients (60 hips 73%) still reported symptoms of LFCN neuropraxia but their Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were not inferior to those who had resolution for pain, function and stiffness: p values of 0.716, 0.171, and 0.238, respectively. The mean score on visual analogue scale decreased from 2.32 (SD 2.11) to 1.76 (SD 1.99). 1 patient (1.2%) reported his activities were limited by his symptoms.

CONCLUSION:

Although the majority of patients still report symptoms related to LFCN neuropraxia, symptoms do improve over time and there are no functional limitations. Even if LFCN neuropraxia following DAA does not lead to functional limitations, all patients should be made aware in order to alleviate any long-term functional concerns.

Incidence of lateral femoral cutaneous nerve neuropraxia after anterior approach hip arthroplasty

BACKGROUND

Although injury to the lateral femoral cutaneous nerve (LFCN) is a known complication of anterior approaches to the hip and pelvis, no study has quantified its' incidence in anterior arthroplasty procedures.

QUESTIONS/PURPOSES

We therefore defined the incidence, functional impact, and natural history of LFCN neuropraxia after an anterior approach for both hip resurfacing (HR) and primary total hip arthroplasty (THA).

METHODS

We followed 132 patients who underwent an anterior hip approach (55 THA; 77 HR). We administered self-reported questionnaires for sensory deficits of LFCN, neuropathic pain score (DN4), visual analog scale, as well as SF-12, UCLA, and WOMAC scores at one year postoperatively. A subset of 60 patients (30 THA; 30 HR) was evaluated at two time intervals.

RESULTS

One hundred seven patients (81%) reported LFCN neuropraxia with a mean severity score of 2.32/10 and a mean DN4 score of 2.42/10. Hip resurfacing had a higher incidence of neuropraxia as compared with THA: 91% versus 67%, respectively. No functional limitations were reported on SF-12, WOMAC, or UCLA scores. Of the subset of 60 patients followed over an average of 12 months, 53 (88%) reported neuropraxia at the first followup interval with only three (6%) having complete resolution at second followup. Improvement in DN4 scores was observed over time: 3.6 versus 2.5, respectively.

CONCLUSIONS

Although LFCN neuropraxia was a frequent complication after anterior approach THA, it did not lead to functional limitations in our patients. A decrease in symptoms occurred over time but only a small number of patients reported complete resolution.

LEVEL OF EVIDENCE

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

Surgical and anatomical landmarks for the perineal branch of the posterior femoral cutaneous nerve: implications in perineal pain syndromes

Object

The perineal branch of the posterior femoral cutaneous nerve (PBPFCN) has received little attention in the literature. Because perineal pain syndromes can be disabling and pudendal nerve surgical decompression/block is often not efficacious, an anatomical study of this cutaneous nerve of the perineum seemed warranted.

Methods

The authors dissected 20 adult cadavers (40 sides) to identify the branching pattern and landmarks for the PBPFCN.

Results

This branch arose directly from the posterior femoral cutaneous nerve in 55% of sides and from the inferior cluneal nerve in 30% of sides. It was absent in 15% of sides. On average, the nerve coursed 4 cm inferior to the termination of the sacrotuberous ligament onto the ischial tuberosity. No PBPFCN was found to pierce the sacrotuberous ligament. The PBPFCN provided 2–3 branches to the medial thigh that continued on to the scrotum and labia major. In general, 2 small ascending branches were identified. In males, one ascending branch traveled inferior to the corpora cavernosum and anterior to the spermatic cord to cross the midline. The other ascending branch traveled to skin at the junction of the perineum and adductor tendon. A single descending branch, approximately 2 mm in diameter, traveled to the inferior scrotum anterior to the testicle in the male specimens and the lower labia majora in the female specimens. Communications between the PBPFCN and the perineal branch of the pudendal nerve were common.

Conclusions

Entrapment of the PBPFCN may be the cause of some forms of the perineal pain syndrome. Specific knowledge of the PBPFCN may assist surgeons in releasing and anesthetizing this cutaneous nerve of the perineum.

Meralgia paresthetica after strenuous exercise

We present three patients with signs and symptoms of meralgia paresthetica (MP) after long-distance walking and cycling. No other possible causes of MP, such as trauma or exogenous compression, were present. A neuropathy of the lateral femoral cutaneous nerve was confirmed in all patients with somatosensory evoked potentials. We propose that conduction block due to local ischemia during repetitive muscle stretching was the probable cause for the neuropathy.

Sep diagnosing neurophaty of the lateral cutaneous branch of the iliohypogastric nerve: case report

The article pertains to the uncommon clinical case of a patient with a proximal neuropathy of the lower extremity. It outlines the electrophysiological evaluation and reviews the medical literature. The electrophysiologic test that most accurately revealed the neuropathy was the segmental somatosensory evoked potential (SEP) of the lateral cutaneous branch of the iliohypogastric nerve. It showed well-defined and replicable cortical waveforms following the excitation of the lateral cutaneous branch of the iliohypogastric nerve in the asymptomatic lower extremity, but failed to present somatosensory evoked potentials arising from the excitation of the contralateral nerve in the symptomatic lower extremity. We did not find any previous reports diagnosing that particular pathology by the use of segmental SEP. In conclusion, it is important to remember that the accurate diagnosis of patients complaining of pain and dysesthesia in the proximal part of the lower extremities can possibly be achieved through the use of electrophysiologic tests such as the segmental SEP.

An anatomical and electrophysiological study of the genitofemoral nerve and some of its targets in the male rat

Anatomical descriptions of the genitofemoral nerve (GFn) innervating the lower pelvic area are contradictory. Here we re-examine its origin and innervation by its various branches of principal target organs in the male rat. Using gross dissection, electrophysiological techniques and retrograde tracing of motoneurones with horseradish peroxidase, we confirm that the GFn originates from lumbar spinal nerves 1 and 2, and that at the level of the common iliac artery it divides into a lateral femoral and a medial genital branch. In contrast to previous studies, we report that the genital and not the femoral branch innervates the abdominal-inguinal skin, and not only the genital but also the femoral branch innervates the cremaster muscle (Cm) surrounding the testes. Motoneurones innervating the Cm proper are located in the ventral nucleus of L1 and L2, and those innervating the muscular transition region of the rostral Cm are located in the ventral nucleus in L1 and the ventrolateral nucleus in L2. The GFn may contribute to male reproductive performance by transmitting cutaneous information during copulation and, via contraction of the Cm to promote ejaculation, the protective displacement of the testes into the abdominal cavity during fighting and as a sperm-protecting thermoregulatory measure.