Lumbosacral Spinal Nerve Roots Research Articles

Variations and anomalies in the structure and branching of lumbosacral spinal nerve roots: a case report and global insights

Aim. The objective of this study is to analyze the clinical course of lumbosacral spinal nerve root anomalies / variants Type I according to the A. Neidre and I. MacNab’s classification, along with a retrospective MRI data analysis before surgery, focusing on the unique branching and topography of the spinal nerve roots. Additionally, we aim to address the relevance of correlating preoperative visualized features with the presence of anatomical anomalies attributed to these spinal nerve root variations, and their implications on the clinical presentation. Our study aims to compare our findings with the global diagnostic experience, classification, and specific aspects of performing discectomies based on individual anatomical characteristics of the lumbosacral region.
 Results. We present data from our own observation, when during surgery, a probable verification of a Type I lumbosacral spinal nerve root anomaly / variation according to the A. Neidre and I. MacNab’s classification was discovered in a patient. The anomaly appeared as a dense mass resembling a nerve root in the structural characteristics but with a significantly larger diameter. It emerged from the dural space at the level of the upper third of the L5 arch and then divided into two parts. A thinner bundle, comparable in diameter to a normal nerve root, exited through the L5-S1 intervertebral foramen, while a considerably thicker bundle followed a path parallel to the axis of the dural sac and exited through the S1-S2 intervertebral foramen.
 Comparison with global clinical observations revealed that despite the significant clinical and surgical implications, several aspects of this anomaly remain poorly studied and require further exploration and systematization.
 Conclusions. The lumbosacral nerve root anomalies (LSNRA) demonstrate a variety of structural variations and branching patterns, which are reflected in different classifications. Among the professional community, the classification of LSNRA, developed by A. Neidre and I. MacNab in 1983 and supplemented by S. M. Burke et al. in 2013, is recognized as the most relevant and frequently applied. While changes in vertebral bone structures can be easily diagnosed using modern imaging methods, preoperative diagnosis of LSNRA proves to be challenging, and the informativeness of standard MRI is limited, as confirmed by the clinical case presented. The dissonance between prominent neurological symptoms and relatively minor disc protrusion allows for the potential presence of a root variation/anomaly when planning the lumbar spine discectomy.
 The most informative diagnostic method for LSNRA is MR neurography. Among the radiological signs of Type I lumbоsacral nerve root anomalies, the following are considered valid: “corner sign”, “fat crescent sign”, and “parallel sign”. The verification of LSNRA is predominantly intraoperatively based on a series of characteristic topographicanatomical features, including atypical locations of the root’s origin from the dural sac, “unusual” nerve root exit angle, even up to a right angle, and technical challenges in root mobilization during routine lumbar discectomy procedures.

THE RELIABILITY OF F-WAVE IN LUMBOSACRAL RADICULOPATHY

Lumbosacral radiculopathy is a clinical disorder caused by impaired function (compression or irritation) of lumbosacral spinal nerve roots. It is manifested by low back pain radiating down into lower limbs in a dermatomal pattern, numbness, loss or decreased reflexes and also muscle weakness along myotomal pattern may be present.There is a wide range of etiologies of lumbosacral radiculopathy, the most common etiology is spondylodegenerative changes as lumbar disc herniation.For definitive diagnosis of lumbosacral radiculopathy, there are variable diagnostic modalities which include magnetic resonance imaging of lumbosacral spine and electrophysiological studies of lower limb nerves.F wave is one of the late responses which is used to study proximal nerve involvement, it is a low amplitude response produced by antidromic activation of motor neurons.Aim of the workOur objective was to evaluate the diagnostic efficacy of F wave as an electro-diagnostic test and its reliability for diagnosing lumbosacral radiculopathy in clinically suspected patients.

Changes in lumbosacral spinal nerve roots on diffusion tensor imaging in spinal stenosis.

Lumbosacral degenerative disc disease is a common cause of lower back and leg pain. Conventional T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) scans are commonly used to image spinal cord degeneration. However, these modalities are unable to image the entire lumbosacral spinal nerve roots. Thus, in the present study, we assessed the potential of diffusion tensor imaging (DTI) for quantitative assessment of compressed lumbosacral spinal nerve roots. Subjects were 20 young healthy volunteers and 31 patients with lumbosacral stenosis. T2WI showed that the residual dural sac area was less than two-thirds that of the corresponding normal area in patients from L3 to S1 stenosis. On T1WI and T2WI, 74 lumbosacral spinal nerve roots from 31 patients showed compression changes. DTI showed thinning and distortion in 36 lumbosacral spinal nerve roots (49%) and abruption in 17 lumbosacral spinal nerve roots (23%). Moreover, fractional anisotropy values were reduced in the lumbosacral spinal nerve roots of patients with lumbosacral stenosis. These findings suggest that DTI can objectively and quantitatively evaluate the severity of lumbosacral spinal nerve root compression.

Spinal Nerve Root Hypertrophy on MRI: Clinical Significance in the Diagnosis of Chronic Inflammatory Demyelinating Polyradiculoneuropathy

To investigate the clinical usefulness of measuring diameters of spinal nerve roots on magnetic resonance imaging (MRI) in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with regard to the diagnosis and estimation of neurofunctional impairment. Fourteen patients with CIDP (mean age, 38.9+/-19.2 years) and 10 controls were enrolled in this study. Diameters of cervical and lumbosacral spinal nerve roots were determined on the short tau inversion recovery image of MRI. Correlations between these diameters and clinical indices, including the conduction velocity of median and tibial nerves, were examined. Mean diameters of cervical and lumbosacral spinal nerve roots in CIDP patients were 6.0 to 6.8 mm and 7.3 to 10.4 mm, respectively. CIDP patients showed higher values of the diameter in C5 (p<0.05), C6 (p<0.05), C7 (p<0.005) and C8 (p<0.01) than controls. C7 and C8 showed significantly negative correlations between diameters of spinal nerve roots and the F-wave conduction velocity (FWCV) (p<0.05). In the lumbosacral region, L3, L4 and S1 showed significantly negative correlations between diameters of spinal nerve roots and FWCV (p<0.005, p<0.0005 and p<0.005, respectively). The latency-time difference between F- and M-waves increased with diameters of spinal nerve roots, and there were significantly positive correlations between them in L3 (p<0.05) and L4 (p<0.005). Hypertrophy of spinal nerve roots shown on MRI may be useful as a clue to the diagnosis of CIDP and also as a clinical marker suggesting impairment of peripheral nerve conduction, particularly FWCV.

Bladder volume-dependent excitatory and inhibitory influence of lumbosacral dorsal and ventral roots on bladder activity in rats

This study was undertaken to examine the role of the afferent and efferent pathways of the lumbosacral spinal nerve roots in the tonic control of bladder activity. Changes of isovolumetric bladder activity were recorded in 21 sympathectomized female rats under urethane anesthesia following transection of the dorsal (DRT) and ventral (VRT) lumbosacral spinal roots, and after intraperitoneal administration of hexamethonium. DRT altered the baseline intravesical pressure in a bladder volume-dependent manner in each animal. The percent change of baseline pressure after VRT following DRT was also dependent upon bladder volume. The percent change of baseline pressure after VRT alone was similarly dependent on bladder volume, but not after VRT followed by DRT. The percent change of baseline intravesical pressure (y)(-9 to +8 cm H(2)O, -56 to +46%) after DRT and VRT depended upon bladder volume (x)(y = 44.7 x -40.4) in all rats. Hexamethonium increased the amplitude of small myogenic bladder contractions after DRT and VRT. In conclusion, the bladder is tonically excited or inhibited by a local reflex pathway and by a parasympathetic reflex pathway that depends on connections with the lumbosacral spinal cord and the pelvic nerves. Both reflex mechanisms are influenced by bladder volume.

Motor response of the leg muscles produced by position-selective stimulation of spinal nerve roots.

To define and measure motor responses of the leg muscles in the ankle associated with position-selective and tetanic stimulation of spinal nerve roots L3-S1. Sixteen lumbosacral spinal nerve roots in 14 subjects were stimulated intraoperatively after surgical exposure and decompression for a herniated disc. Each contact of a spiral cuff multielectrode was wrapped around the root and used to excite a spatially defined population of axons beneath the electrode. The motor response from each stimulated position was evaluated in terms of three-dimensional vector torque in the ankle. Each position at which the stimulating electrode was placed around the root exhibited the same vector torque qualitatively, but at different thresholds. The root was most excitable ventrally. The S1 roots responded with a uniform three-dimensional torque pattern: plantar flexion plus lateral leg and foot rotation plus inversion. All L5 roots responded by plantar flexion. Dorsiflexion torque was possible only with stimulation of the L3 and L4 roots. Eversion was not possible with stimulation of the S1 roots or with most of the L5 roots. Position-selective stimulation of the extrathecal spinal nerve roots influences the threshold of the biomechanical response, the torque recruitment dynamics, and the magnitude of three-dimensional vector torque. Selective activation of some leg muscles or agonist muscle groups with stimulation of a single nerve root could not be achieved owing to the low spatial selectivity of the stimulation design and/or the low muscle specificity of motor fascicles in the root. Direct extrathecal stimulation of spinal nerve roots has some hypothetical advantages over stimulation of other sites along the peripheral nerves, owing to their unique anatomy, and may contribute to functional electrical stimulation of the lower extremities. Further investigation with a more selective multielectrode configuration and the use of multiple root stimulation is suggested.

Motor Response of the Leg Muscles Produced by Position-selective Stimulation of Spinal Nerve Roots

OBJECTIVE To define and measure motor responses of the leg muscles in the ankle associated with position-selective and tetanic stimulation of spinal nerve roots L3–S1. METHODS Sixteen lumbosacral spinal nerve roots in 14 subjects were stimulated intraoperatively after surgical exposure and decompression for a herniated disc. Each contact of a spiral cuff multielectrode was wrapped around the root and used to excite a spatially defined population of axons beneath the electrode. The motor response from each stimulated position was evaluated in terms of three-dimensional vector torque in the ankle. RESULTS Each position at which the stimulating electrode was placed around the root exhibited the same vector torque qualitatively, but at different thresholds. The root was most excitable ventrally. The S1 roots responded with a uniform three-dimensional torque pattern: plantar flexion plus lateral leg and foot rotation plus inversion. All L5 roots responded by plantar flexion. Dorsiflexion torque was possible only with stimulation of the L3 and L4 roots. Eversion was not possible with stimulation of the S1 roots or with most of the L5 roots. CONCLUSION Position-selective stimulation of the extrathecal spinal nerve roots influences the threshold of the biomechanical response, the torque recruitment dynamics, and the magnitude of three-dimensional vector torque. Selective activation of some leg muscles or agonist muscle groups with stimulation of a single nerve root could not be achieved owing to the low spatial selectivity of the stimulation design and/or the low muscle specificity of motor fascicles in the root. Direct extrathecal stimulation of spinal nerve roots has some hypothetical advantages over stimulation of other sites along the peripheral nerves, owing to their unique anatomy, and may contribute to functional electrical stimulation of the lower extremities. Further investigation with a more selective multielectrode configuration and the use of multiple root stimulation is suggested.

Anterior lumbosacral radiculopathy after intrathecal methotrexate treatment

Intrathecal chemotherapy with methotrexate or cytosine arabinoside is the standard approach to prophylaxis and treatment of central nervous system leukemia in children. Progressive paraplegia, one of the devastating neurologic complications related to this mode of treatment, has been attributed to spinal cord toxicity. Reported are three children who developed progressive paraparesis after intrathecal methotrexate administration followed by complete or partial recovery. Gadolinium enhancement of anterior lumbosacral spinal nerve roots was demonstrated in all three patients, and an elevation of cerebrospinal fluid immunoglobulin G synthesis was evident in two patients with more severe symptoms. The clinical data suggest that anterior lumbosacral radiculopathy is also a type of neurologic complication associated with intrathecal methotrexate treatment.

Lumbosacral anterolateral spinal arteries and brief review of "accessory" longitudinal arteries of the spinal cord.

The lumbosacral anterolateral spinal arteries (LALSA) were studied in 14 injected lumbosacral spinal cords. Contrary to many previously published opinions, which claimed that virtually all of the formerly described "accessory" longitudinal arteries of the vasa corona, were too inconstant to be of significance, the LALSA in this series were reliably present bilaterally and averaged a length of 8.4 cm. They ran in the acute angles formed by the emergence of the fascicles of the lumbosacral anterior spinal nerve roots and in this position, served as the origin for most of the proximal radicular arteries that supply the cranial half of the motor roots of the cauda equina. A review of the literature and analysis of other accessory longitudinal spinal arteries revealed that two other pairs of accessory spinal vessels, the lateral cervical spinal arteries (LCSA) and the lateral spinal arterial axes (LSA), have a demonstrable functional role and were sufficiently constant, along with the LALSA, to warrant inclusion in detailed descriptions of human spinal cord vasculature.

The experimental basis of sciatica

Although injuries of the lumbosacral spinal nerve roots in the spinal canal have been recognized as the primary cause of the symptoms of sciatica, the basic pathophysiologic mechanisms of the condition are still poorly understood. It is evident that mechanical deformation of a nerve root is significantly linked to the symptoms of sciatica. It was also recently confirmed experimentally that nucleus pulposus may induce structural and functional changes in adjacent nerve roots, as well as having potential inflammatogenic properties. Probably, the potency of the disc-derived materials has previously not been fully recognized. Recent research is now trying to define which basic pathophysiologic events at the cellular or sub-cellular level are responsible for the nerve root injury. It is to be hoped that the results of such research will provide resources to diagnose and treat patients earlier and more specifically, and that the number of chronic cases should be dramatically reduced.

INTRINSIC VASCULATURE OF THE LUMBOSACRAL SPINAL NERVE ROOTS

INTRINSIC VASCULATURE OF THE LUMBOSACRAL SPINAL NERVE ROOTS

Traction Injury of the Lumbosacral Spinal Nerve Roots

Traction Injury of the Lumbosacral Spinal Nerve Roots

The intrinsic vasculature of the lumbosacral spinal nerve roots.

The observations made in this study strongly support the concept that spinal nerve roots in general and the human lumbosacral spinal nerve roots in particular are structurally, vascularly, and metabolically unique regions of the nervous system. Peculiarities of their intrinsic vasculature and supporting connective tissue may account for suspected "neuroischemic" responses to pathologic mechanical stresses and inflammatory conditions associated with degenerative disease of the lower spine. It is hoped that the newly described features of the radicular vasa nervorum (to avoid confusion with the dissimilar blood supply of peripheral nerves, the term "vasa radiculorum" might be more accurate) may advance the understanding of certain aspects of lower spine symptomatology and provide some basis for much needed future research.

Urethral responses during selective electrostimulation of lumbosacral spinal nerve roots in the female spinal dog.

Urethral responses on the urethral pressure profile (UPP) during selective electrostimulation of the ventral or dorsal roots in a group of lower lumbar (L5-7) or sacral (S1-3) nerves were observed in female spinal (C1-transected) dogs. The UPPs were recorded by using a balloon catheter, and square pulse wave of 5 V, 10 Hz, 1 msec was applied for electrostimulation of the spinal nerve root. The UPPs were analyzed by dividing the functional profile length (FL) into three equal parts and comparing the height of maximal clossure pressure at each UPP segment. After lumbosacral rhizotomies proximal to the electrodes, stimulation of the lower lumbar ventral roots produced a marked elevation at the proximal third (bladder neck) of UPP, while similar response was found at the middle third (midsphincteric urethra) and distal third (external urethral sphincter) of UPP during the sacral ventral roots stimulation. The stimulation of the dorsal roots of the lower lumbar and sacral nerves also produced a similar response as that of the ventral roots stimulation though less in amplitude. So it could be concluded that in female dog the sphincteric urethra might receive a functional innervation from the lower lumbar and sacral spinal segments in somewhat different manners.