Angle Of Nerve Root Research Articles

Investigating the effect of anatomical variations in the response of the neonatal brachial plexus to applied force: Use of a two-dimensional finite element model.

The brachial plexus is a set of nerves that innervate the upper extremity and may become injured during the birthing process through an injury known as Neonatal Brachial Plexus Palsy. Studying the mechanisms of these injuries on infant cadavers is challenging due to the justifiable sensitivity surrounding testing. Thus, these specimens are generally unavailable to be used to investigate variations in brachial plexus injury mechanisms. Finite Element Models are an alternative way to investigate the response of the neonatal brachial plexus to loading. Finite Element Models allow a virtual representation of the neonatal brachial plexus to be developed and analyzed with dimensions and mechanical properties determined from experimental studies. Using ABAQUS software, a two-dimensional brachial plexus model was created to analyze how stresses and strains develop within the brachial plexus. The main objectives of this study were (1) to develop a model of the brachial plexus and validate it against previous literature, and (2) to analyze the effect of stress on the nerve roots based on variations in the angles between the nerve roots and the spinal cord. The predicted stress for C5 and C6 was calculated as 0.246 MPa and 0.250 MPa, respectively. C5 and C6 nerve roots experience the highest stress and the largest displacement in comparison to the lower nerve roots, which correlates with clinical patterns of injury. Even small (+/- 3 and 6 degrees) variations in nerve root angle significantly impacted the stress at the proximal nerve root. This model is the first step towards developing a complete three-dimensional model of the neonatal brachial plexus to provide the opportunity to more accurately assess the effect of the birth process on the stretch within the brachial plexus and the impact of biological variations in structure and properties on the risk of Neonatal Brachial Plexus Palsy.

Comparison of Nerve Root Direction of Lumbar Spine in Different Positions

Background: Endoscopic surgery in lumbosacral spine has been a procedure for spine surgeons since 1999. The most common position for patients in prone position, but in some situation, it is impossible to proceed, such as in overweight patients or patients with associated injury. It is necessary to compare the anatomy of nerve roots in different positions such as supine, prone, and lateral decubitus position. Therefore, the magnetic radiography imaging is a proper tool for evaluating nerve roots. Material and Methods: The authors designed a study where 14 patients would engage in the magnetic resonance imaging (MRI) process in three different positions. The first group, control group, would get the MRI at supine position while the second and the third group would proceed with MRI at prone and lateral decubitus position, respectively. Then, the authors would measure the values by drawing the line between upper border of the exiting nerves and the lateral border of traversing nerves. Hence, if the nerve root angle was different from the control group by more than 10 degrees, it would be clinically significant because of changes in the Kambin’s triangle. Results: The demographic data were not statistically significant for all population in the three groups. All of nerve roots direction, at the L3-L5 level, were not similar in supine, prone, and lateral decubitus positions. Conclusion: The present study will help orthopedic surgeon be aware that the position of patients affected nerve roots direction. Pre-operative MRI must be done, and pathological level should be specified despite the above and below part. Even though the result showed no statistical difference, the angle of more than 10 degrees affected the increased area of Kambin’s triangle. However, it would be favorable for the expansion of Kambin’s area in prone and lateral decubitus. Keywords: Position of MRI; Nerve roots direction in lumbar spine; Kambin’s triangle and position

The value of contrast-enhanced three-dimensional isotropic T2-weighted turbo spin-echo SPACE sequence in the diagnosis of patients with lumbosacral nerve root compression

To investigate the diagnostic value of contrast-enhanced three-dimensional (3D) T2-weighted turbo spin-echo SPACE (T2-SPACE) sequence in LNRC. A total of 90 surgically confirmed LNRC patients with 165 explored nerve roots were enrolled in this study. Diagnostic values were quantified using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy. The consistency between 2D MRI and 3D T2-SPACE MRI was quantified using kappa test. The compression of specific branch in nerve root was evaluated on 2D MRI, 3D T2-SPACE MRI, and surgical findings. The pedicle height, vertebral body height (VH), proximal tilting angle of nerve root (PTA) were measured on MR images. The sensitivity, specificity, PPV, NPV, and accuracy by 2D MRI were 78.3%, 72.7%, 94.9%, 34.0%, and 77.6%, respectively. For 3D T2-SPACE MRI imaging, the sensitivity, specificity, PPV, NPV, and accuracy were 91.6%, 86.4%, 97.8%, 61.3%, and 90.9%, respectively. 2D MRI and 3D T2-SPACE MRI for detection of intra-foramen and extra-foramen nerve compression showed poor homogeneity (Kappa = 0.333, Kappa = 0.276, respectively). Smaller VHs and larger PTAs could be indicators for the diagnosis of foraminal nerve root compression. 3D T2-SPACE MRI had a higher sensitivity, specificity, PPV, NPV, and accuracy than 2D MRI for detecting LNRC. The 3D T2-SPACE scan could be a good substitute to routine 2D MRI in LNRC diagnosis, especially for foraminal nerve root compression patients. III.

Measurement of spinal root angle at spinal canal and foraminal levels in cases of facet arthropathy: T2-weighted turbo spin echo magnetic resonance myelography with SPACE technique.

Magnetic resonance myelography (MRM) with three-dimensional (3D) T2-weighted (T2W) turbo spin echo (TSE) sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) may be a guide to the etiology of low back pain. To research the efficiency of a 3D T2W TSE SPACE MRM sequence for visualization of anatomic details of spinal nerve root at the spinal canal and lateral recess levels in the patients with low back pain. Lumbar spinal MRM 3D T2W TSE SPACE was performed in a total of 70 patients (median age 46 years). Patients were imaged while lying in a supine position with straightened legs. According to the degree of facet arthropathy findings, patients were divided into four separate subgroups in our retrospective cross-sectional study. Spinal nerve root angle was measured within the spinal canal and at lateral recess level, and facet joint angle and lumbar lordosis measurements were measured by two radiologists, independently. Lumbar level was strongly negatively correlated with facet joint angle (r = -0.95) as well as nerve root angle within the spinal canal (NRASC) (r = -0.857) and at the lateral recess level (NRALR) (r = -0.947). Intracanal decline of the spinal root angle caused by spinal stenosis findings was also observed (P < 0.05). For the measurements of NRASC and NRALR, inter-observer correlation was 0.85 and 0.82 for the spinal canal and at lateral recess level, respectively. 3D T2W SPACE in NRASC and NRALR provided high resolution images for evaluation. Therefore, this method may be a qualitative guide for the clinician and the surgeon in terms of root anatomy before any intervention.

Anatomical Features of Neural Foramen at T12â€"L1 Level for Endoscopic Transforaminal Approach of Paramedian and Foraminal Disc Herniations: An Anatomical Study on Fresh Human Cadavers.

To explore the anatomic features of the neural foramen in particularly at the T12-L1 level in order to assess reveal the safety and efficiency of the endoscopic transforaminal approach for paramedian and foraminal disc herniations at this level. The study included 15 fresh human cadavers. The soft tissues were removed at the T12-L1 level and bony tissues, were exposed including the transverse processes. The bilateral facets and pars interarticulares at this level were resected revealing the foraminal anatomy and exiting roots. The anatomical structures constituting the triangular safe working zone (TSWZ) were explored. The nerve root length, nerve root width, nerve root angle, TSWZ height, and base of TSWZ base, nerve root width, nerve root angle and disc height were recorded. The root length is the hypotenuse of the TSWZ between the axilla of the exiting root and the lateral margin of the pedicle, and the mean root length was 14.94 ± 2.45 mm. The dural height is the interval between the axilla of the exiting nerve root axilla and the superior end plate of the caudal vertebra, and the mean of the dural height was 10.95 ± 1.74 mm. The base of TSWZ is the distance between the lateral margin of the dural sac and the medial margin of the exiting root, and the mean measurement for the base measurement was 11.83 ± 2.26 mm. According to the results data from our cadaveric study, we believe that Kambin’s triangular working zone is a safe area to consider for the endoscopic transforaminal approach at the T12-L1 level, especially for paramedian and foraminal disc herniations.

Morphological anatomy of thoracolumbar nerve roots and dorsal root ganglia.

The aim of this study is to ascertain the anatomic parameters of the spinal roots and dorsal root ganglia and to demonstrate their clinical significance. Samples from 24 adult autopsy subjects were obtained from roots and dorsal root ganglia at levels L1 through L5. The anatomic parameters of epidural nerve roots: the distance between the epidural nerve roots and the proximal edge of the dorsal root ganglia and the average diameter of the nerve root gradually, increased from L1 to L5. The midline nerve root angle gradually decreased from L1 to L5. The anatomic parameters of subarachnoid nerve roots: the length of subarachnoid nerve roots and both the ventral and dorsal roots' diameter, increased from L1 to L5. The number of ventral and dorsal rootlets per nerve root ranged from one to three. The anatomic parameters of dorsal root ganglia: the length and width of the thoracic and lumbar dorsal root ganglia, gradually increased from L1 to L5. The locations of the dorsal root ganglia were recorded as the intraspinal, intraforaminal and extraforaminal using some bony landmarks. Most dorsal root ganglia located intraforaminally, and the extraforaminal type is more common in the L5 root than other thoracic and lumbar roots, regardless of age. This knowledge is a must not only to avoid complications but also for the success, safety and effectiveness of microsurgical operations.

Microsurgical nerve root decompression in scoliotic lumbar spines—the relationship between important anatomical structures in correlation to imaging and implications for daily practice: anatomic cadaveric study

OBJECT In a retrospective study in cadavers, the authors investigated the anatomical parameters between the convex and concave side in lumbar scoliosis for microsurgical discectomy and the decompression of spinal stenosis. Microsurgical intervention is the gold standard for lumbar herniotomy or the decompression of the spinal stenosis. However, the risk for complications during these procedures is higher due to the anatomical variations caused by the scoliosis. METHODS In 4 adult cadaveric scoliotic lumbar spines, the authors studied the anatomical relationship between important structures for performance of microsurgical discectomy or decompression, such as the dural sac, spinal nerve roots, and adjacent anatomical structures. They measured the following distances and compared these findings with those acquired using conventional radiographs in daily practice: nerve root outlet-ganglion center, nerve shoulder-superior disc, nerve shoulder-pedicle, nerve axilla-pedicle, nerve axilla-lower pedicle, ganglion center-pedicle, ganglion center-lower pedicle, and nerve root angle. RESULTS The mean distance of nerve root outlet-ganglion center, nerve shoulder-superior disc, nerve shoulder-pedicle, nerve axilla-pedicle, and ganglion center-pedicle was significantly different between the convex and concave side (all p < 0.05), in contrast to the results of nerve axilla-lower pedicle and ganglion center-lower pedicle, which both related to the pedicle of the lower segment (difference not significant). CONCLUSIONS For the first time, information on the anatomical variations between convex and concave sides in scoliotic lumbar spines is described, supported by comparisons with radiographic examinations. These results confirm a topographic anatomical discrepancy. This knowledge can be used in daily perioperative practice for patients undergoing microsurgical decompression.

The relation between the lumbar vertebrae and the spinal nerves for far lateral lumbar spinal approaches

The far lateral approaches to the lumbar spine require accurate knowledge of regional anatomy. The aim of this study is to evaluate the course of the lumbar nerve roots and their relation to important bony landmarks. Seven adult male cadavers fixed with formaldehyde were used. Morphometric parameters, including the lumbar nerve root diameters, the angle between the nerve roots and the midline, the transverse process length, the inter-transverse process height and width, and the relation between the nerve roots and the transverse processes of the caudal vertebrae were measured. It was observed that the diameter of the nerve roots, and the angle between the nerve roots and the midline, and the distance between the nerve roots and the lateral edge of the superior articular process increased gradually from L1 to L5. The diameter of the nerve root was 4.9 ± 0.5 mm for L1 and 7.5 ± 1.0 mm for L5. The midline nerve root angle was 36.1 ± 1.6° mm for L1 and 40.4 ± 1.4° mm for L5. The distance between the nerve root and the lateral edge of the superior articular process was 6.5 ± 1.0 mm for L1 and 11.4 ± 1.6 mm for L5. The nerve roots crossed the transverse processes of the caudal lumbar vertebrae. The nerve roots of L1 and L2 crossed the transverse processes in their first two quarters, the L3 nerve root crossed the transverse process in its second, third or fourth quarters, and the L4 nerve roots crossed the L5 transverse process in its third and fourth quarter or even external to it. Descending toward the lower lumbar vertebrae, the diameter of the lumbar nerve root increases and the nerve roots exit the intervertebral foramen with a larger angle. The special relation between the nerve roots and the caudal vertebra transverse process should be remembered during far lateral lumbar spine approaches.

Anatomic relations between the lumbar pedicle and the adjacent neural structures.

The authors analyzed anatomic parameters between the lumbar pedicles and the dural sac as well as the spinal nerve roots. To determine quantitatively the anatomic relations between the lumbar pedicle and adjacent dural sac and nerve roots. Posterior transpedicular screw fixation is the most commonly used method of instrumentation for stabilization of the unstable lumbar spine. A thorough knowledge of the unique anatomy of the lumbar pedicle and adjacent neural structures may avoid or minimize neurologic complications with pedicular screw placement. Fifteen adult cadavers were obtained to evaluate quantitatively the anatomic relations of the lumbar pedicle to the adjacent neural structures. After removal of the laminas and facets, the lumbar pedicles, dural sac, and nerve roots were exposed. Direct measurements were taken from the pedicle to the dural sac medially, to the nerve roots superiorly and inferiorly, and between the pedicles. Also, the superoinferior diameter of the nerve root and the frontal angle of the nerve root were measured. Symmetric structures were measured bilaterally. No consistent changes from L1 to L5 were found in all parameters. The mean distances from the lumbar pedicle to the dural sac medially and to the adjacent nerve roots superiorly and inferiorly for all levels were 1.5 mm, 5.3 mm, and 1.5 mm, respectively. The mean interpedicular distance ranged from 23.2 to 24.4 mm. The mean superoinferior diameter of the nerve root ranged from 3.8 to 4.6 mm. The mean nerve root angle ranged from 33.7 degrees to 39.2 degrees. On the basis of this study, improper placement of the pedicle screw medially or caudally in the lumbar spine should be avoided.

Location of the extraforaminal lumbar nerve roots. An anatomic study.

Twelve cadavers were used to determine the anatomic location of the extraforaminal lumbar nerve root in the intertransverse space. After exposure of the transverse processes of the lumbar spine and the extraforaminal lumbar nerve roots, direct measurements, including the nerve root angle, nerve root diameter, distance to the superior facet, and the intertransverse space, were made bilaterally. The results showed that the extraforaminal nerve root angle and diameter and the distance between the superior facet and lateral limit of the nerve root consistently increased from cephalad to caudal. The largest dimension for height and width of the intertransverse space was found at the level of L3-4, and the smallest was found at the level of L5-S1. This information may be helpful in minimizing the incidence of injury to the lumbar nerve root during a posterolateral approach to lumbar disc.

Anatomic relations of the thoracic pedicle to the adjacent neural structures.

This study analyzed anatomic parameters between the thoracic pedicles and the spinal nerve roots. To quantitatively determine the anatomic relations of the thoracic pedicle to the adjacent neural structures. Pedicular screw placement carries with it potential hazard to the surrounding neural structures, especially in the thoracic spine. No studies exist regarding the anatomic relations of the thoracic pedicle to the adjacent nerve roots. Fifteen cadavers were obtained for study of the thoracic spine. All soft tissue was dissected off the thoracic spine. Laminectomy and total removal of the superior and inferior articular facets was then performed on C7-T1 through T12-L1 to expose the pedicles, nerve roots, and dura. Measurements were taken from the pedicle to the nerve root superiorly and inferiorly as well as between the pedicles. Also, the superoinferior diameter of the nerve root and the frontal angle of the nerve root were measured. Symmetrical structures were measured bilaterally. The results showed that no epidural space could be found between the dural sac and the pedicle in all 15 cadavers. The average distances from the thoracic pedicle to the adjacent nerve roots superiorly or inferiorly at all levels ranged from 1.9 to 3.9 mm and from 1.7 to 2.8 mm, with a minimum of 1.3 mm, respectively. The interpedicular distance increased from T1 (13.8 mm) to T3, slightly decreased in T4-T5, then gradually increased to T12 (16.6 mm). The superoinferior diameter of the nerve root increased consistently from 2.9 mm at T1 to 4.6 mm at T11. The frontal nerve root angle decreased consistently from T1 (120.1 degrees) to T12 (57.1 degrees), except at T4-T5. This study suggested that more care be taken into consideration in placing a transpedicular screw in the transverse plane than in placing a screw in the sagittal plane in the thoracic spine.