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Concept: Sciatic nerve

169

OBJECTIVE: To present a group of anatomical findings that may have clinical significance. DESIGN: This study is an anatomical case report of combined lumbo-pelvic peripheral nerve and muscular variants. Setting: University anatomy laboratory. Participants: One cadaveric specimen. METHODS: During routine cadaveric dissection for a graduate teaching program, unilateral femoral and bilateral sciatic nerve variants were observed in relation to the iliacus and piriformis muscle, respectively. Further dissection of both the femoral nerve and accessory slip of iliacus muscle was performed to fully expose their anatomy. RESULTS: Piercing of the femoral nerve by an accessory iliacus muscle combined with wide variations in sciatic nerve and piriformis muscle presentations may have clinical significance. CONCLUSIONS: Combined femoral and sciatic nerve variants should be considered when treatment for a lumbar disc herniation is refractory to care despite positive orthopedic testing.

Concepts: Muscle, Biology, Dissection, Lumbar plexus, Piriformis muscle, Sciatica, Sciatic nerve, Spinal disc herniation

27

Piriformis syndrome is an uncommon cause of sciatica. It is frequently posttraumatic or in relation with anatomic abnormalities; its diagnosis is often difficult, and it needs the exclusion of common causes of sciatica. Piriformis syndrome caused by drug-induced myopathy in relation with use of statin has not been described before. We report the case of a 60-year-old woman with a history of dyslipidemia treated by atorvastatin since 3 years, who complained of a chronic pain in the left buttock radiating to the posterior thigh and knee that had been increasing during the previous 3 months. At physical examination, the patient has lameness at walking. The lumbar spine was not tender and had full range of motion. Findings on all radicular provocation tests were normal, and tests stretching the piriformis muscle were positive. Radiographs of the pelvis and lumbar spine were unremarkable. Magnetic resonance images of the lumbar spine and pelvis was performed, showing high signal intensity in T2-weighted sequences of the piriformis muscle. Treatment with atorvastatin was occasionally discontinued, and the patient reports an improvement of the sciatic pain. Reintroduction of atorvastatin was associated with relapse of the sciatic pain. Thus, clinical features and magnetic resonance imaging findings confirm that sciatic pain was related with piriformis myopathy as an adverse effect of statin.

Concepts: Causality, Spinal disc herniation, Sciatic nerve, Pelvis, Piriformis muscle, Magnetic resonance imaging, Piriformis syndrome, Sciatica

26

Posteromedial tarsal tunnel syndrome is a disorder affecting the tibial nerve or its branches. Diagnosis is established on the basis of physical examination and can be confirmed by electrophysiological evidence. However, diagnostic imaging is always required to identify the possible site of compression. High-resolution ultrasound (US) is playing an increasingly important role in the study of the nerves thanks to a series of advantages over magnetic resonance imaging, such as lower costs and widespread availability, high spatial resolution, fast examination using axial scans, dynamic and comparative studies, possibility of carrying out a study with the patient in the standing position, US Tinel sign finding, and the contribution of color/power Doppler US. We present the results obtained in a series of 81 patients who underwent US imaging between 2008 and 2013 due to posteromedial tarsal tunnel syndrome.

Concepts: Patient, Radiology, Sciatic nerve, Tarsal tunnel syndrome, Medical diagnosis, Ultrasound, Medical imaging, Magnetic resonance imaging

23

The research on artificial nerve conduits has become a focus of study in peripheral nerve reconstruction so as a possible replacement for the treatment of autologous nerve grafts in clinics. In this study, we used longitudinally oriented collagen conduit (LOCC) combined with nerve growth factor (NGF) to reconstruct long distance of sciatic nerve defects (35 mm) in adult dog model. The long term follow-up evaluation demonstrated that the LOCC/NGF conduit allowed functional and morphological nerve regeneration at the transection site of the injured sciatic nerve. Furthermore, the functional study confirmed that when NGF was loaded onto LOCC it promoted a better recovery of regenerated axons than LOCC alone. The gastrocnemius muscle mass in the LOCC/NGF group was significantly greater than in the LOCC alone group. The results indicated that when LOCC conduit combined with NGF it would provide a preferential environment for sciatic nerve regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017.

Concepts: Conduit, Sciatic nerve, Action potential, Nerve, Sciatica, Muscle, Nerve growth factor

5

Dementia is the cardinal feature of Alzheimer’s disease (AD), yet the clinical symptoms of this disorder also include a marked loss of motor function. Tau abnormal hyperphosphorylation and malfunction are well-established key events in AD neuropathology but the impact of the loss of normal Tau function in neuronal degeneration and subsequent behavioral deficits is still debated. While Tau reduction has been increasingly suggested as therapeutic strategy against neurodegeneration, particularly in AD, there is controversial evidence about whether loss of Tau progressively impacts on motor function arguing about damage of CNS motor components. Using a variety of motor-related tests, we herein provide evidence of an age-dependent motor impairment in Tau-/- animals that is accompanied by ultrastructural and functional impairments of the efferent fibers that convey motor-related information. Specifically, we show that the sciatic nerve of old (17-22-months) Tau-/- mice displays increased degenerating myelinated fibers and diminished conduction properties, as compared to age-matched wild-type (Tau+/+) littermates and younger (4-6¬†months) Tau-/- and Tau+/+ mice. In addition, the sciatic nerves of Tau-/- mice exhibit a progressive hypomyelination (assessed by g-ratio) specifically affecting large-diameter, motor-related axons in old animals. These findings suggest that loss of Tau protein may progressively impact on peripheral motor system.

Concepts: Sciatica, Muscle, Sciatic nerve, Action potential, Axon, Nervous system, Alzheimer's disease

3

Exercise regimens are established methods that can relieve neuropathic pain. However, the relationship between frequency and intensity of exercise and multiple cellular responses of exercise-induced alleviation of neuropathic pain is still unclear. We examined the influence of exercise frequency on neuropathic pain and the intracellular responses in a sciatic nerve chronic constriction injury (CCI) model.

Concepts: Sciatic nerve, Sciatica

3

To investigate the behavior of the sciatic nerve during hip rotation at subgluteal space.

Concepts: Sciatica, Sciatic nerve

3

Pain that extends from the buttock down the course of the sciatic nerve is common. Nearly 85% of cases are associated with a disk disorder. The causes, assessment, and management of sciatica are discussed.

Concepts: Piriformis muscle, Spinal disc herniation, Sciatica, Sciatic nerve

2

The aim of this study was to assess sciatic nerve conductivity in athletes with a history of hamstring strain injuries. Twenty-seven athletes with a history of hamstring strain injuries were included in the injured group. The control group consisted of 16 uninjured participants. We measured the proximal and distal latencies and calculated the sciatic nerve conduction velocity to evaluate neuronal conductivity. The results were expressed as median values and interquartile ranges. Both proximal latency and distal latency of the injured limb in the injured group were significantly longer than those of the uninjured limb (p<0.05). The nerve conduction velocity of the injured limb in the injured group was significantly lower than that of the uninjured limb (p<0.05). There were no significant side-to-side differences in the control group. Sciatic nerve conductivity impairments may exist in athletes with a history of hamstring strain injuries.

Concepts: Scientific control, Median, Sciatic nerve, Injuries, Sprain, Injury, Strain, Nerve conduction study

2

We have previously shown that nerve inflammation (neuritis) and transient vinblastine application lead to axonal mechanical sensitivity in nociceptors innervating deep structures. We have also shown that these treatments reduce axonal transport, and proposed that this leads to functional accumulation of mechanically sensitive channels in the affected part of the axons. While informing the etiology of mechanically induced pain, axonal mechanical sensitivity does not address the common report of ongoing radiating pain during neuritis, which could be secondary to the provocation of axonal chemical sensitivity. We proposed that neuritis and vinblastine application would induce sensitivities to noxious chemicals, and that the number of chemo-sensitive channels would be increased at the affected site. In adult female rats, nerves were either untreated, or treated with complete Freund’s adjuvant (to induce neuritis) or vinblastine. After 3-7 days, dorsal root teased fiber recordings were taken from Group IV neurons with axons within the sciatic nerve. Sciatic nerves were injected intraneurally with a combination of noxious inflammatory chemicals. While no normal sciatic axons responded to this stimulus, 80% and 38% of axons responded in the neuritis and vinblastine groups, respectively. In separate experiments, sciatic nerves were partially ligated and treated with complete Freund’s adjuvant or vinblastine (with controls), and after 3-5 days were immunolabeled for the histamine 3 receptor. The results supported that both neuritis and vinblastine treatment reduce transport of the histamine 3 receptor. The findings that nociceptor axons can develop ectopic chemical sensitivity are consistent with ongoing radiating pain due to nerve inflammation.

Concepts: Sciatic nerve, Nociceptor, Immune system, Nerve, Pain, Action potential, Axon, Nervous system