Aberrant Dorsal Nerve Root as a Concomitant Cause of Spinal Cord Tethering Associated with a Dorsal Type Lipomyelomeningocele in a Child With Caudal Agenesis.

ABSTRACT: Tethered cord syndrome is a neurological disorder closely associated with congenital spinal dysraphism. Aberrant dorsal nerve roots may be one of the possible and relatively rare tethering pathologies, especially in the complex form of occult spinal dysraphism such as caudal regression syndrome or split cord malformation. We report an illustrative case of caudal regression syndrome with spinal cord tethering due to a combination of a contiguous bundle of an aberrant dorsal nerve root, and a dorsal-type lipomyelomeningocele, with a thickened filum terminale treated with microneurosurgical untethering.

Transiting Nerve Rootlet Abnormalities on MRI after Lumbar Laminectomy: Associations with Persistent Postoperative Pain.

OBJECTIVE: To determine whether changes in the transiting nerve rootlet or its surroundings, as seen on MRI performed after lumbar hemilaminectomy, are associated with persistent postoperative pain (PPP), commonly known as the failed back surgery syndrome. MATERIALS AND METHODS: Seventy-three patients (mean age, 61 years; 43 males and 30 females) who underwent single-level partial hemilaminectomy of the lumbar spine without postoperative complications or other level spinal abnormalities between January 2010 and December 2018 were enrolled. Two musculoskeletal radiologists evaluated transiting nerve rootlet abnormalities (thickening, signal alteration, distinction, and displacement), epidural fibrosis, and intrathecal arachnoiditis on MRI obtained one year after the operations. A spine surgeon blinded to the radiologic findings evaluated each patient for PPP. Univariable and multivariable analyses were used to evaluate the association between the MRI findings and PPP. RESULTS: The presence of transiting nerve rootlet thickening, signal alteration, and ill-distinction was significantly different between the patients with PPP and those without, for both readers (p ≤ 0.020). Conversely, the presence of transiting nerve rootlet displacement, epidural fibrosis, and intrathecal arachnoiditis was not significantly different between the two groups (p ≥ 0.128). Among the above radiologic findings, transiting nerve rootlet thickening and signal alteration were the most significant findings in the multivariable analyses (p ≤ 0.009). CONCLUSION: On MRI, PPP was associated with transiting nerve rootlet abnormalities, including thickening, signal alterations, and ill-distinction, but was not associated with epidural fibrosis or intrathecal arachnoiditis. The most relevant findings were the nerve rootlet thickening and signal alteration.

Intraspinal characteristics of thoracic spinal nerve roots anomalies.

Purpose: The anomalous anatomical arrangement of the thoracic spinal nerve roots within the spinal canal can complicate the surgical treatment of several pathologies. The aim of this work was to reveal intraspinal anatomical variations of the thoracic spinal nerve roots.Methods: Anatomical study on 43 cadavers with a mean age of 53.7. After opening the spinal canal and dural sac, intradural and extradural anomalies of the thoracic spinal nerve roots were documented. Extradural communicating branches were excised, histologically processed and examined for the presence of nervous tissue.Results: We found 14 cases (32.6%) of intraspinal thoracic nerve root variations: intradural in 8 cases (18.6%), intradural communicating branches in 3 cases (6.97%), extradural anatomical variations occurred 6 cases (13.95%), 2 cases (4.65%) had extradural communicating branches between the nerve roots, 1 case had simultaneous occurrence of intradural and extradural communications (0.23%). All the results are differentiated according to the plexus type. In macroscopic extradural thoracic communicating branch had no nervous tissue on microscopy.Conclusions: This study describes intraspinal anatomical variations of thoracic spinal nerve roots. Knowledge of these variables should help prevent the failure of several medical procedures.

Identification of abnormalities in the lumbar nerve tract using diffusion-weighted magnetic resonance neurography.

INTRODUCTION: Abnormalities of the lumbar nerve tract caused by congenital variations or high nerve root take-off angles are difficult to visualize. Diffusion-weighted magnetic resonance neurography (DW-MRN) has recently been introduced for imaging of the lumbosacral region. The aims of this study were to identify lumbar nerve tract abnormalities caused by congenital variation or a high nerve root take-off angle using DW-MRN and to assess the diagnostic value of this imaging modality. METHODS: A total of 573 magnetic resonance images from 575 patients (261 men, 314 women; mean age 58.5 years) with low back/leg pain were retrospectively analyzed. We classified congenital variations in the lumbar nerve roots using the Neidre and MacNab criteria and investigated nerve roots with a take-off angle of 60° or more. RESULTS AND DISCUSSION: Congenital variations were identified in 8 patients (9 nerve roots, 1.6%). The most commonly identified variation was in the sacral nerve root (n = 5) followed by the L4 (n = 3) and L5 (n = 1) nerve roots. All variations identified were on the left side. There were 3 cases of type 1a variation, 1 of type 1b, 1 of type 2, and 4 of type 3. In total, 210 (36.6%) of the magnetic resonance images showed high nerve root take-off angles at the intervertebral foramen that was caused by disk herniation, spondylolisthesis, or osteophytes with degeneration. Patients with high nerve root take-off angles were significantly older than those without (P < 0.05). These slides can be retrieved under Electronic Supplementary Material.

Extradural Characteristics of the Origins of Lumbosacral Nerve Roots.

BACKGROUND AND STUDY AIMS: A great number of unsuccessful intervertebral herniated disk surgeries in the lumbosacral region have highlighted the importance of a comprehensive knowledge of the different types of nerve root anomalies. That knowledge gained by anatomical studies (and intraoperative findings) might contribute to better results. In our study we focused on intraspinal extradural lumbosacral nerve root anomalies and their possible role in radiculopathy. MATERIAL AND METHODS: The study was performed on 43 cadavers within 24 hours after death (32 men and 11 women). Bodies were dissected in the prone position, and a laminectomy exposed the entire spinal canal for the bilateral examination of each spinal nerve root from its origin to its exit through the intervertebral foramen or sacral hiatus. Uncommon extradural features in the lumbosacral region were pursued and documented. The spinal dural sac was also opened, aimed at recognizing the normotyped, prefixed, or postfixed type of plexus. RESULTS: A total of 20.93% of anomalies of extradural lumbosacral nerve root origins were observed, with the normotyped plexus prevailing. We observed atypical spacing of exits of lumbosacral roots (four cases), two roots leaving one intervertebral foramen (one case), extradural anastomoses (two cases), and missing extradural nerve root courses (two cases). The results were differentiated according to the normotyped, prefixed, or postfixed plexus type. CONCLUSION: Results of similar studies dealing with anomalies of lumbosacral nerve roots were aimed at improving the results of herniated disk surgeries because ∼ 10% of misdiagnoses are related to ignorance of anatomical variability. Our observations may help explain the differences between the clinical picture and generally accepted anatomical standards.

The clinical significance of redundant nerve roots of the cauda equina in lumbar spinal stenosis patients: A systematic literature review and meta-analysis.

OBJECTIVES: Decompression surgery for lumbar spinal stenosis (LSS) is the most performed spine surgery procedure in patients older than 65 years. Around 40% of LSS patients scheduled for decompression surgery have evidence of redundant nerve roots (RNR) of the cauda equina on their magnetic resonance images (MRI). Little is known about the clinical significance of RNR in LSS patients. The objective was to assess the effects of RNR on clinical scores and recovery in older adults diagnosed with LSS. PATIENTS AND METHODS: A systematic literature search was performed in April 2018 on PubMed, Web of Science, MEDLINE and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Prospective and retrospective cohort studies undertaken to assess differences in clinical outcomes in patients diagnosed with LSS with versus without evidence of RNR on their MRIs were selected. Two authors independently selected studies, abstracted data and assessed risk of bias. We calculated weighted mean differences (WMD) for continuous variables and odds ratio (OR) for variables reported in frequencies. RESULTS: Seven studies comprising a total of 1046 LSS patients were included in the meta-analysis. LSS patients with evidence of RNR (RNR+) were older, WMD 5.7 95% CI [2.2-9.2], p = 0.001, had smaller cross sectional area (CSA) of the stenotic level, WMD -12.2 95% CI [-17.7 to -6.7], p < 0.0001 and longer symptom onset duration, WMD 13.2 95% CI [-0.2-26.7], p = 0.05. The pooled preoperative clinical score in the RNR + group was worse but the difference was not statistically significant, WMD -3.8 95% CI [-7.9 to 0.2], p = 0.07. After decompression surgery RNR + patients had worse clinical scores, -4.7 95% CI [-7.3 to -2.1], p = 0.0004 and lower recovery rates, -9.8 95% CI [-14.8 to -4.7], p = 0.0001. CONCLUSION: There is limited quality evidence that RNR + patients are older, have a longer symptom history and present higher degrees of lumbar stenosis as given by the narrow CSA in comparison to RNR- patients. After decompression surgery RNR + patients have worse clinical scores and lower recovery rates. In view of these results RNR can be seen as a negative prognostic factor in LSS patients.

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.

Nerve root anomalies: making sense of a complicated literature.

INTRODUCTION: Nerve root anomalies (NRAs) are a set of well-described congenital irregularities for which several classification systems have been devised over the years. CONCLUSION: This comprehensive review examines the anatomy and characteristics of NRAs; their surgical, radiographic, and cadaveric prevalence rates; clinical and radiographic presentations; and surgical management. In addition, the top 5 NRA classification systems are presented and related.

Nerve root anomalies detected intra-operatively technical nuances towards achieving a successful surgical outcome: our experience of three case reports at a tertiary level centre.

OBJECTIVE: Analysis of three case reports of nerve root anomalies detected intra-operatively and its implications. DESIGN: Data collected during one year prospective non-randomised study using hospital records. SETTING: Single tertiary care centre. SUBJECTS: 3 patients in one year period.

Intraspinal extradural variations of nerve roots.

INTRODUCTION: The aim of this work is to point out the intraspinal extradural anatomical variations of nerve roots and their possible participation in radiculopathy. METHODS: The anatomical study was performed in 33 cadavers at a mean age of 46.5 and up to 24h from death. All extradural anastomoses between nerve roots were excised and examined histologically for the presence or absence of nervous tissue. The type of the plexus was defined by subtracting from the root C2. RESULTS: Findings with the normotype of plexus formation prevailed in 24 cases (72.7%). Variations in its formation were observed in 9 cases (27.3%). The prefixed type in 6 cases (18.2%), post-fixed type in 3 cases (9.1%). We did not observe the formation of the isolated prefixed or post-fixed types in the brachial or lumbosacral plexuses. Extradural anatomical variations occurred in 20 cases (60.6%). They were more frequent on the left, in 10 cases (30.3%), bilateral in 3 cases (9.1%). In 8 instances (24.2%), the atypical spacing, including four in the lumbosacral region, was observed. Variations occurred more frequently in variations of formation of the plexus. CONCLUSIONS: This study allowed us to identify and describe unpublished intraspinal extradural anatomical variations of nerve roots and their interrelationships throughout the spinal canal with their potential influence on the clinical picture. Anatomical preparations revealed a higher incidence of intraspinal extradural variations, mainly between sacral roots. The reliance of their incidence of the type of plexus was observed.

Lumbosacral Conjoined Root Anomaly: Anatomical Considerations of Exiting Angles and Root Thickness.

AIM: Conjoined nerve roots (CNR) can be damaged during lumbar disc surgery and lead to neuropathic pain due to excessive retraction. The purpose of this study was to investigate the factors that facilitate the identification of CNRs that can lead to the loss of fragments in the secondary axilla, nerve root injury or unpleasant surprises during lumbar disc surgery. Accordingly, we aimed to measure the thicknesses and exit angles of the nerve roots close to the pedicle to obtain scientific data regarding rare double roots. MATERIAL AND METHODS: The data of 612 patients who were operated for lumbar disc disease in our hospital between 2012 and 2014 were reviewed retrospectively. Twenty one cases of CNR were detected in this series. RESULTS: The mean nerve root thickness was 1.92 ± 0.45 mm for medially located roots and 3.33 ± 0.95 mm for laterally located roots. The comparison of medially located roots versus laterally located roots revealed a significant difference in mean values (p < 0.0001). The mean exit angle was 12.290± 4.890 for medially located roots, and 22.110 ± 5.420 for laterally located roots (p < 0.0001). In addition, the exit angles of the medially and laterally located roots increased as going down to caudal levels, (p=0.005, p=0.042). CONCLUSION: CNRs are congenital anomalies that are usually diagnosed during the surgical procedure and affect the success of discectomy. The presence of a more medially located or thinner root during surgical exploration and the absence of the fragment in the axilla in extruded or sequestered discs usually indicate a conjoined nerve root closer to the pedicle.

Anatomical variations in the brachial plexus roots: implications for diagnosis of neurogenic thoracic outlet syndrome.

Neurogenic thoracic outlet syndrome (NTOS) is the most common type of TOS. Typically it results from impingement of the neurovasculature as it passes between the anterior and middle scalene muscles; this classic anatomical relationship being the foundation of clinical diagnosis. Positional testing relies on vascular compromise occurring when the subclavian artery is compressed in this space. This study describes several anatomical variations observed in this relationship. Sixty-five cadavers (35m/30f) were assessed to determine the frequency and extent of brachial plexus branching variants. A total of thirty-one variations from "classic" anatomy were observed (47.7%). In two specimens (3.1%), the entire superior trunk coursed completely anterior to the anterior scalene in a position of relative vulnerability. In 27 instances, a portion of or the entire superior trunk pierced the anterior scalene muscle, and in two, the middle trunk also pierced the muscle belly. Interestingly, while two bilateral branching variations were observed, the majority occurred unilaterally, and almost exclusively on the left side. There were no sex differences in frequency. The high frequency of these variations and their potential to predispose patients to neurogenic TOS suggest that current diagnostic methods may be insufficient in clinical diagnosis. Due to lack of vascular compromise, patients with the piercing variant would not display positive signs on the traditional positional tests. The use of ultrasound to determine the route of the brachial plexus could determine whether this variation is present in patients who suffer from TOS symptoms but lack a diagnosis based on traditional positional testing.

Radiosurgery target location and individual anatomical variation in trigeminal nerves.

OBJECT: The authors evaluated individual anatomical variations in the trigeminal nerves of patients with medically intractable trigeminal neuralgia and clarified the relationships among the variations, radiosurgical target locations, and the clinical outcomes after high-dose Gamma Knife surgery (GKS). METHODS: From 2006 through 2011, the authors conducted a retrospective review of 106 cases of primary or secondary trigeminal neuralgia consecutively treated with GKS targeting the dorsal root entry zone (DREZ) for which a maximal dose of 90 Gy and a 20% isodose line to the brainstem were used. A questionnaire was used to evaluate patients' pre- and post-GKS clinical conditions. To evaluate individual anatomical variations among trigeminal nerves, the authors used 3 parameters: the length of the trigeminal nerve in the cistern (nerve length), the length of the target between the radiation shot and the brainstem (targeting length), and the ratio between nerve length and targeting length (targeting ratio). RESULTS: The median length of the trigeminal nerves in the 106 patients was 9.6 mm (range 6.04-20.74 mm), the median targeting length was 3.8 mm (range 1.81-10.84 mm), and the median targeting ratio was 38% (range 13%- 80%). No statistically significant differences in pain relief and pain recurrence were detected among patients with these various nerve characteristics. However, radiation-induced facial hypesthesia correlated with nerve length and targeting ratio (p < 0.05) but not with absolute distance from the brainstem (targeting length). CONCLUSIONS: In trigeminal neuralgia patients who received DREZ-targeted GKS, the rate of pain relief did not differ according to anatomical nerve variations. However, the frequency of facial hypesthesia was higher among patients in whom the nerve was longer (> 11 mm) or the targeting ratio was lower (< 36%). Adjusting the target according to the targeting ratio, especially for patients with longer nerves, can reduce facial hypesthesia and enable maintenance of effective pain control.

Functional variability of sacral roots in bladder control.

OBJECT: Sacral roots are involved in sensory, autonomic, and motor innervation of the lower limbs and perineum. Theoretically, it can be assumed that the S-3 root level innervates the bladder; however, clinical practice shows that this distribution can vary. Few researchers have studied this variability. METHODS: The authors conducted a retrospective study involving 40 patients who underwent surgery requiring an electrophysiological exploration of the sacral roots. They performed stimulations for the monitoring of muscular (3 Hz, 1 V) and bladder responses under cystomanometry (30 Hz, 10 V). RESULTS: Although the S-3 roots were involved in bladder innervation in all cases, they were exclusively involved (i.e., the only nerve roots involved) in only 8 of 40 cases. In the remaining 32 cases, other sacral nerve roots were involved. The most common association was S-3+S-4 (12 cases), followed by S-2+S-3 (6 cases), S-2+S-3+S-4 (5 cases), and S-3+S-4+S-5 (2 cases). Stimulation of S-2 could sometimes induce bladder contraction (15 cases, 40%); however, the amplitude was often low. S-4 nerve roots were involved in 24 of 40 cases (60%) in the bladder motor function, whereas S-5 roots were only involved 7 times (17%). Occasionally, we noticed a horizontal asymmetry in the response, with a predominant response from the right side in 6 of 7 cases, always with a major S-3 response. CONCLUSIONS: This is the first study showing a significant horizontal and vertical variability in the functional distribution of sacral roots in bladder innervation. These results show the variability of cauda equina syndromes and their forensic implications. These data should help with the monitoring of sacral roots and the performance of several tasks during surgery, including neurostimulation and neuromodulation.

Conjoined lumbosacral nerve roots: direct demonstration on MR neurography.

Indirect signs of conjoined nerve roots have been well described on conventional lumbar spine magnetic resonance imaging. Direct demonstration of developmentally united nerve roots makes it quite easily appreciable on MR neurography imaging and has not been described before. We report two cases of conjoined nerve roots and their imaging appearances on three-dimensional magnetic resonance neurography. A brief description of the imaging technique and relevance of these anatomic variants is discussed.

A unique case of intradural communicating branches between the accessory nerve and the dorsal roots of the cervical spinal nerves.

OBJECTIVE: The accessory nerve has cranial and spinal roots. The cranial roots emerge from the medulla, whereas the spinal roots arise from motor cells within the ventral horn of C1-C7 segments of the spinal cord. Communications have been described between the spinal accessory nerve rootlets and the dorsal rootlets of cervical spinal nerves. In the present case, we report a communication that has not been reported before and discuss the functional anatomy. MATERIALS AND METHODS: During the dissection of the craniovertebral junction of a 67-year-old formalin-fixed adult male cadaver, a connection between the spinal accessory nerve rootlets and the dorsal rootlets of the cervical spinal nerves was observed. RESULTS: A communication between the spinal rootlets of the accessory nerve and the dorsal roots of cervical spinal nerves was present on the right and left side. On the right, a communication between the accessory nerve spinal rootlet and the dorsal rootlet of the fourth cervical spinal nerve existed. On the left, there were two branches from the lowest accessory nerve spinal rootlet, one run ventrally and the other dorsally to the spinal rootlet and reached the dorsal root of third cervical spinal nerve. The dorsal root of C1 did not exist on either the right or the left side. Further, an unusual spinal accessory nerve formation was also observed. DISCUSSION: This case does not fit into any of the previously described classifications in the literature. Therefore, the different variations concerning the communications between the spinal rootlets of the accessory nerve and the cervical spinal nerves should be kept in mind during both surgical, especially radical neck dissections, and nonsurgical evaluations.

Intraoperative conjoined lumbosacral nerve roots associated with spondylolisthesis.

Lumbosacral nerve roots anomalies may produce low back pain. These anomalies are reported to be a cause for failed back surgery. They are usually left undiagnosed, especially in endoscopic discectomy techniques. Any surgery for entrapment disorders, performed on a patient with undiagnosed lumbosacral nerve roots anomaly, may lead to serious neural injuries because of an improper surgical technique or decompression. In this report, we describe our experience with a case of L5-S1 spondylolisthesis and associated congenital lumbosacral nerve root anomalies discovered during the surgical intervention, and the difficulties raised by such a discovery. Careful examination of coronal and axial views obtained through high-quality Magnetic Resonance Imaging may lead to a proper diagnosis of this condition leading to an adequate surgical planning, minimizing the intraoperatory complications.