Stretching of roots contributes to the pathophysiology of radiculopathies

Novel Transdural Epiarachnoid Approach for Large Central Disk Herniation in Upper Lumbar Spine

BACKGROUND AND IMPORTANCE

The treatment for large central disk herniation (LCDH) at upper lumbar spine is often challenging. Previous reports showed various surgical strategies, such as microdiscectomy with posterior fixation, endoscopic surgery, and microdiscectomy through transdural approach. However, there is no consensus regarding which surgical option is better for LCDH at upper lumbar spine. In this report, we describe the novel transdural epiarachnoid approach (TDEA), which uses the corridor of epiarachnoid space for microdiscectomy. Compared with classical transdural approaches, this novel approach may reduce risks of postoperative cerebrospinal fluid leakage and the development of arachnoiditis.

CLINICAL PRESENTATION

A 69-yr-old man presented with progressive bilateral radiating leg pain, intermittent claudication, and low back pain. Magnetic resonance images and computed tomography scans revealed LCDH at L2/3 level. We performed microdiscectomy using the TDEA. Postoperative course was uneventful, and his symptoms were relieved after surgery.

CONCLUSION

The novel TDEA for LCDH at upper lumbar spine is illustrated with a video. This novel approach has an advantage of the preservation of subarachnoid components compared with classical transdural approaches.

Venous congestion as a central mechanism of radiculopathies

Compression of roots/nerves can disrupt some of their functions, but does not necessarily cause pain. This is illustrated by the frequency of nearly asymptomatic spinal stenosis or disc herniations. In fact, pain of radiculopathies (and nerve entrapments) may mostly be the consequence of intraneural oedema induced by microscopical venous stasis around roots/spinal ganglia (or nerves) not or poorly shown by imaging. This narrative review first lists arguments for a role of congestion of vasa-nervorum in the pathophysiology of radiculopathies, including those induced by disc herniation and spinal stenosis, but also other sources of overpressures in spinal venous plexuses (pregnancy, vena cava atresia and thrombosis, portal hypertension, epidural varices, arterio-venous fistula, vertebral hemangioma or hemangioblastoma). It also details sources of venous congestion around nerves outside the spine, from pelvis (May-Thurner syndrome, Nut-cracker syndrome) to buttocks (superior and inferior gluteal veins), and even thighs and legs. A better recognition of a preeminent role of venous congestion in radiculopathies, plexopathies, and nerve entrapments, should have major consequences: (i) discard the dogma that compression is mandatory to induce root/nerve suffering, since root/nerve adherences in two locations can impair blood flow in vasa-nervorum through root/nerve stretching; (ii) implementation of sensitive techniques to visualise impingement of blood flow around or within roots and nerves; (iii) better prevention of roots/nerves adherence, or arachnoiditis induced by extravascular fibrin deposition secondary to venous stasis.; (iv) optimizing treatments dampening clot formation and/or extravascular fibrin leakage in the intradural/peridural spaces, or around roots/nerves, like guided injection of tissue plasminogen activator.

Isolation and Characterization of Extracellular Vesicle from Mesenchymal Stem Cells of the Epidural Fat of the Spine

Study Design

An experimental study with extracellular vesicles (EVs) from mesenchymal stem cell (MSC) of the epidural fat (EF) of the spine.

Purpose

This study aims to isolate the exosomes from epidural fat-derived mesenchymal stem cells (EF-MSCs) and fully characterize the EF-MSC-EVs.

Overview of Literature

EF-MSCs were reported in 2019, and a few studies have shown the positive outcomes of using EF-MSCs to treat specific spine pathologies. However, MSCs have significant limitations for conducting basic studies or developing therapeutic agents. Although EVs are an emerging research topic, no studies have focused on EVs, especially exosomes, from EF and EF-MSCs.

Methods

In this study, we isolated the exosomes using the tangential flow filtration (TFF) system with exosome-depleted fetal bovine serum and performed the characterization tests via western blotting, reverse transcription–polymerase chain reaction, nanoparticle tracking analysis (NTA), and transmission electron microscopy.

Results

In transmission electron microscopy, the exosome had a diameter of approximately 100–200 nm and had a spherical shape, whereas in the NTA, the exosome had an average diameter of 142.8 nm with a concentration of 1.27×10¹⁰ particles/mL. The flow cytometry analysis showed the expression of CD63 and CD81. The western blotting analysis showed the positive markers.

Conclusions

These findings showed that isolating the exosomes via TFF resulted in high-quality EF-MSC exosome yield. Further studies with exosomes from EF-MSC are needed to evaluate the function and role of the EF tissue.

Inadequacies of the Lasègue test, and how the Slump and Bowstring tests are useful for the diagnosis of sciatica

Diagnosis of sciatica mainly relies on pain reproduction by stretching of the lumbar roots since neurological examination and medical history are usually not sufficient to guarantee diagnosis. The Lasègue test is the most popular method, which starts with the straight leg-raising test (SLR). However it is not perfect, and is not always well performed or interpreted. Passive ankle dorsiflexion at the end of the SLR (Bragard test) is more sensitive, but can also remain normal in some cases of sciatica. Other stretching tests can help to recognise lumbar root damage in patients with poorly defined pain in a lower extremity: firstly, the Christodoulides test, i.e. reproduction of L5 sciatic pain by a femoral stretch test; secondly, the Slump test, performed on a patient in a sitting position, by slowly extending their painful leg then passively bending their neck (or the opposite); and thirdly, the Bowstring test, which requires, at the end of the Lasègue test, once the knee has been slightly flexed, pressing on the course of the peroneal and/or tibial nerves in the popliteal fossea to try and reproduce the exact pain felt by the patient. The combination of all these tests takes less than 2minutes, and could improve both the sensitivity and specificity of the physical examination for the diagnosis of sciatica. This article is a review of the limitations of the Lasègue/SLR tests and of the efficacy of these other tests for stretching the lumbar roots.

Severe lumbar radiculopathy with epidural venous plexus engorgement in a morbidly obese pediatric patient: A case report

INTRODUCTION

Engorgement of the epidural venous plexus (EVP) is a rare cause of nerve root impingement. Dilated epidural veins cause compression of the thecal sac and spinal nerve roots, leading to lumbar radiculopathy.

PATIENT CONCERNS

Here we describe a case of severe lumbar radiculopathy in a 15-year-old morbidly obese boy.

DIAGNOSIS

Enhanced lumbar magnetic resonance imaging revealed left sided L1-L2 disc protrusion and engorgement of the lumbar EVP, resulting in narrowing of the thecal sac in the entire lumbar spine. There was no evidence of an intra-abdominal mass, thrombosis of the inferior vena cava, or vascular malformation.

INTERVENTIONS

A caudal epidural block was administered under fluoroscopic guidance. The patient reported a 30% reduction in pain intensity for just 1 day.

OUTCOMES

The patient has been followed up for 2 years. He continues to take medication, including morphine sulfate 15 mg, gabapentin 300 mg, and oxycodone 20 mg per day. He is on a diet with exercise for weight reduction.

CONCLUSION

An engorged EVP should be considered in the differential diagnosis of radiculopathy in morbidly obese patients.

Movements of the lumbo-sacral nerve roots in the spinal canal induced by straight leg raising test: an anatomical study

PURPOSE

The pain involved in the herniated discs could be generated by some mobility of the nerve roots during straight leg raising (SLR). SLR produces some movement of nerves, but the magnitude of this displacement needs to be thorough, that is why we have investigated lumbo-sacral nerve root displacement in the spinal canal during the passive straight leg raise (SLR).

METHODS

Fourteen cadavers underwent laminectomy to mark the nerve roots of L2-S1 with lead balls. X-rays were taken during different movements imposed on the body: bilateral hip extension, left SLR then right and bilateral SLR. By superimposing these images two by two, the displacement of the nerve roots is quantified numerically during the various SLR maneuvers with respect to the reference position corresponding to the bilateral hip extension.

RESULTS

The median range of the different nerve root movements ranged from 0.10 to 0.51 cm (p < 0.05 except for the L2 root) when the left SLR is applied, from 0.26 to 0.48 cm (p < 0.05) with the right SLR and from 0.30 to 0.65 cm (p < 0.05) with a bilateral SLR. No statistically significant relationship was found between age and movement value.

CONCLUSIONS

The lumbo-sacral nerve roots in the spinal canal region move statistically significantly in response to the clinically applied SLR test, except for L2 root during the left SLR. This movement is symmetric and greater when a bilateral SLR is applied. These anatomical results are correlated with those observed empirically in clinical practice.