Dorsal Rami Research Articles

The sulci of the lateral superior parietal lobule: anatomical overview and nomenclatural consideration.

Discrepancies in the terminology describing sulcal structures within the lateral superior parietal lobule prompted our comprehensive investigation to clarify their morphology and nomenclature. We reviewed literature from the 19th century to the present, focusing on the intraparietal sulcus, interparietal sulcus, superior parietal sulcus, transverse parietal sulcus, paroccipital sulcus, and transverse occipital sulcus. Additionally, we analyzed neuroimaging data from 40 healthy young adults and two cadavers. Our investigation revealed that the original term intraparietal sulcus, introduced by Sir Turner, described a complex structure comprising the inferior segment of the postcentral sulcus, a horizontally extending component into the occipital lobe, and the transverse occipital sulcus. We also found that the superior parietal sulcus is often synonymous with transverse parietal sulcus, the sulcus of Brissaud is an eponym that shall describe the paroccipital sulcus's dorsal parietal ramus, and the transverse occipital sulcus is the combination of the occipital rami of the paroccipital sulcus. Additionally, we identified an unnamed transverse segment of the intraparietal sulcus, the intraparietal sulcus-transverse. Based on these observations, we consider that the sulci of the lateral superior parietal lobule primarily include the intraparietal sulcus, with longitudinal and transverse segments, the transverse parietal sulcus of Brissaud, and the paroccipital sulcus of Wilder.

Endoscopic Joint Capsule and Articular Process Excision for the Treatment of Lumbar Facet Joint Syndrome: A Retrospective Study.

Dorsal ramus medial branch radiofrequency ablation is reported to be effective for refractory lumbar facet joint syndrome. However, as nerve fibers can regenerate, the therapeutic effect was reported to be short and last only 6 to 12 months. Previously, we reported a novel endoscopic joint capsule and articular process excision procedure. In that case, a satisfying effect was achieved by removing the culprit hyperplastic articular synovial entrapped in the joint space endoscopically. We presume this treatment is an etiologic treatment and can exert longer-term efficacy. This retrospective clinical trial aimed to elucidate the longer-term efficacy as well as the safety profile of the procedure. This was a retrospective descriptive study. The participants underwent endoscopic joint capsule and articular process excision procedures. The Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) before the operation, and at 3 months, 6 months, 1 year, and 2 years post-operation were recorded by reviewing medical charts and conducting telephone interviews. A total of 234 participants were evaluated in the trial. After participant screening, 13 participants were included in the final analysis. The VAS score was reduced from (median (P25, P75)) 6 (4.5, 6) at pre-operation to 2 (0, 4) at 1-year post-operation and 0 (0, 1) at 2-year pre-operation. The ODI score was reduced from 37.78 (27.09, 59.95) at pre-operation to 8.89 (2.22, 24.34) at 1-year post-operation and 6 (0.02, 11.11) at 2-year post-operation. The difference was statistically significant. Further subgroup analysis demonstrated that a narrowed intervertebral space was a possible relevant factor for poor outcomes. No procedure-related complications were reported. Endoscopic joint capsule and articular process excision is an effective and safe procedure for refractory lumbar facet joint syndrome. The effectiveness duration can last up to 1 to 2 years.

Fish That Fish for Fish-A Peculiar Location of "Fishing Motoneurons" in the Striated Frogfish Antennarius striatus.

In lophiform teleosts, the first dorsal fin has evolved as a specialized structure called the "illicium" equipped with the esca, which is a modified skin flap used to attract small fish for predation. The motor control system of the illicium, however, remained unknown. The present study investigated the innervation of muscles for the illicium and morphology of motoneurons innervating them in the striated frogfish Antennarius striatus. We found that the dorsal ramus of occipital nerve innervates the muscles. Motoneurons for the illicium are present in the dorsolateral zone of ventral horn at the medullo-spinal boundary level, forming a cluster somewhat distinct from other motoneurons of the ventral horn. Motoneurons for the second to fourth dorsal fins and pectoral fin were located in the ventrolateral and ventromedial zones of ventral horn, respectively, whereas those of the dorsal trunk muscle in the dorsomedial zone of ventral horn. Motoneurons for the first dorsal spine of white-spotted pygmy filefish were also investigated for species comparison and were found to locate in the ventrolateral zone of ventral horn, similarly to the motoneurons for the second to fourth dorsal fins of the frogfish. These results suggest that motoneurons for the illicium have become segregated from other motoneurons to be situated in an unusual dorsal position for a motoneuron pool of a dorsal fin, in concert with the evolution of specialized "fishing behavior" performed by the illicium.

Cadaveric study of the ultrasound-guided inter-transversospinalis plane block in dogs for the cervical epaxial musculature region.

Blockage of the dorsal rami of the spinal nerves (DRSN) provides analgesia to the epaxial musculature area in dogs. However, techniques to block the DRSN at the cervical level in dogs haven't yet been investigated. This study aimed to study the anatomy of the cervical area, and to describe a new ultrasound (US)-guided inter-transversospinalis plane (ITP) block technique at the 5th cervical vertebrae (C5). Fourteen adult canine's cadavers were used in this blinded, cadaveric, experimental study. One cadaver for cryo-section, one for anatomical research and twelve to do an ITP injection using 0.3 mL/kg (HV) or 0.15 mL/kg (LV) of dye/contrast solution in each lateral at C5, followed by a computed tomography and anatomical dissection.The HV and LV groups stained a median (range) of 4.67 (3-6) and 3.67 (2-5) DRSN into the ITP, respectively (P<0.017). Stained DRSN in the splenius plane were found in nine (75%) HV and five (41.66%) LV injections, respectively. Spread in the epidural space was found in two dogs using LV. One of them was injected into the ITP (4.33 %) while the other one was done accidentally outside of this plane. The paravertebral spread was found in one injection of each group. There was no dye of the ventral rami of the spinal nerves. The US-guided ITP injection is feasible in dog cadavers. The LV injected just after the medial surface of the semispinalis capitis muscle is recommended to avoid a possible extensive epidural spread.

Evaluation of the feasibility of equine in-vivo ultrasound technique for the medial branch of the dorsal ramus of the cervical spinal nerves

Ultrasound-guided local anaesthesia is commonly used in veterinary orthopaedics for horses. This study aimed to assess an in vivo ultrasound technique for the medial branch of the dorsal branch of the cervical spinal nerves (MB-DBCSNs) in horses and compare the performance of clinicians with different experience levels. Ten healthy, skeletally mature horses were examined using radiographic and ultrasound (US) techniques in the cervical area (C3–C7). Four operators with varying experience conducted US examinations using a 10 MHz linear and 6 MHz curvilinear transducer over ten training sessions. The number of cervical nerves visualized was recorded. A chi-square test was used to analyse the impact of training, anatomical location, and operator experience on the identification of facet joints. Operator agreement was evaluated with Cohen’s K test. The operators assessed 80 MB-DBCSNs, with radiographs and identified 70 healthy and 10 pathological facet joints. Training significantly improved visualization success, reaching 90% in later sessions. Cranial facet joints (C3–C5) were more frequently visualized (81%) than caudal ones (C5–C7) were (59%). US performance was influenced by the operator’s skill, and agreement among operators ranged from slight to fair. Overall, practice improved cervical nerve visualization in vivo, particularly for cranial nerves, but the technique requires a long learning curve because of low levels of operator agreement.

Anatomy of mamillo-accessory foramen and prevalence of ossified mamillo-accessory ligament in lumbar vertebrae related to age.

Ossification of the mamillo-accessory ligament (MAL) results in the formation of a mamillo-accessory foramen (MAF), which is associated with aging. The MAL tethers the medial branches of the lumbar dorsal rami to the lumbar vertebrae. A MAL ossified at the lumbar vertebrae can cause low back pain by compressing the medial branch of a dorsal ramus. Age ranges related to ossification of the MAL have not been reported in previous studies. The objective of the present study was to determine the prevalence of ossification of the MAL in the lumbar column and its relationship to aging, and to measure the newly formed MAF at each level of the lumbar vertebrae. This study examined 935 dried lumbar vertebrae from 187 donors at Khon Kaen University, Thailand, consisting of 93 females and 94 males. The research focused on ossification patterns of the MAL, categorizing them into three patterns. We found that over 50% of ossified MAL occurred in the 30-45-year-old range and the frequency increased with age. The prevalence of ossified lumbar MAL was 72.73%, especially in L5 on the left side in females (76.92%). The width of the MAF did not differ significantly between the sexes, but it was greater on the left side (2.46 ± 1.08; n = 76) than the right (2.05 ± 0.95; n = 72) (p = 0.016). Ossification of the MAL into the MAF progresses with age, leading to low back pain from nerve compression. Physicians should be aware of the MAF during anesthesia block to treat low back pain.

Ultrasound-guided retromammillary injections in dogs: a feasibility, descriptive and anatomical study

ObjectiveTo evaluate the feasibility of an ultrasound-guided technique targeting the medial branches of the dorsal ramus of the spinal nerves (DRSN) by injecting a dye solution at the caudal aspect of the base of lumbar mammillary processes [i.e. the retromammillary (RM) space]. Study designFeasibility, descriptive, anatomical study. AnimalsEleven canine cadavers. MethodsUsing anatomical dissections, the relationship between the mammillary processes and the branches of the DRSN of the thoracolumbar and lumbar spine was studied in two cadavers. Subsequently, ultrasound-guided RM injections were administered in nine cadavers, randomly assigned to low volume (LV; 0.01 mL kg–1) of a dye solution at multiple points from L3 to L6 on one side, and high volume (HV; 0.4 mL kg–1) at a single L4 point on the contralateral side. Gross anatomical dissections were immediately performed after the injections. The RM injections were feasible if ultrasonographic landmarks were identifiable in at least 80% of cases, and 80% of LV injections showed medial branch staining. A one-sample binomial test was used for testing feasibility. ResultsThe medial branches emerged shortly after the DRSN exited the intervertebral foramen and traveled towards the caudal aspect of the base of the mammillary process, which served as the target injection point. With LV, 36 out of 36 (100%) injected medial branches were stained, meeting the criteria of feasibility (p < 0.001). The median (range) number of stained medial branches per cadaver were 4 (4–4) and 2 (1–3), with LV and HV, respectively. Although no lateral branches were stained with LV, 1 (0–2) was stained with HV. Neither ventral branch staining nor epidural spread was noted in any cadaver. Conclusions and clinical relevanceUltrasound-guided RM injections are feasible and allow for selective staining of the medial branch of the DRSN in canine cadavers at the lumbar spine.

Anatomical assessments of injectate spread stratified by the volume of the intertransverse process block at the T2 level

BackgroundThis cadaveric study aimed to analyze injectate spread to target nerves during a single-injection, ultrasound-guided intertransverse process block.MethodsAn ultrasound-guided intertransverse process block with three different injectate volumes was administered to...

Erector spinae plane infiltration and anterior rami of spinal nerve: a cadaveric study

BackgroundThe erector spinae plane block (ESP block) is frequently employed for thoracic, abdominal, and spinal surgeries, yet its precise mechanism of action remains a subject of debate. While initially postulated...

Full-Endoscopic Sacroiliac Joint Denervation for Painful Sacroiliac Joint Dysfunction: A Prospective 2-Year Clinical Outcomes and Predictors for Improved Outcomes.

Full-endoscopic sacroiliac joint denervation (FE-SJD) is a novel technique for the management of pain secondary to sacroiliac joint dysfunction. The aim of this study was to assess the long-term efficacy, safety, clinical outcomes, and outcome predictors of uniportal full-endoscopic sacroiliac joint denervation. From 2019 to 2021, a total of 47 consecutive patients with pain secondary to sacroiliac joint dysfunction underwent uniportal FE-SJD through posterior approach by a single fellowship-trained spine surgeon. A retrospective analysis of perioperative parameters, complications, and clinical outcomes were obtained prospectively. The patient cohort had a mean age of 59.4 ± 14.0 years, with 63.8% females. Symptom duration averaged 62.1 ± 53.7 months. The mean operative time was 57.1 ± 16.8 minutes. All patients were discharged on the same day of surgery. Significant improvement was noted in preoperative visual analog score (back) and Oswestry Disability Index scores at 3, 6, 12 months, and 2 years (P < .001). Thirty-four patients (72.3%) returned to normal functioning with an average of 82% pain relief and a satisfaction rate of 78.7% at a mean follow-up of 18.2 ± 13.1 months. There were no intraoperative complications. One patient had postoperative right L5 dysesthesia. Seven patients (14.9%) underwent contralateral FE-SJD due to satisfaction with the index procedure but residual pain on the contralateral side. Concomitant lumbar issues correlated with less functional improvement at 2 years (P = .009). The long-term clinical results of FE-SJD are favorable. Endoscopic denervation of the dorsal rami branches supplying the sacroiliac joint represents a safe, effective, and durable option to address pain secondary to sacroiliac joint dysfunction. A significant factor that influences outcomes is the presence of concomitant lumbar pathology. Further research is needed to compare this technique with current available treatment options.

Vacuum Disc Phenomenon Turned Gassy Disc Herniation: A Case Report

BACKGROUND: The vacuum phenomenon is a radiologic finding that results from gas accumulation within degenerated discs, joints, or vertebrae. This gas can herniate, causing back pain and/or radiculopathy. Asymptomatic imaging abnormalities can be coincidental and/or non-concordant with clinical presentation therefore warranting close evaluation. CASE REPORT: This 45-year-old man, previously diagnosed with lumbar facet arthropathy, returned to the clinic for left-sided axial low back pain. Imaging revealed that a gas filled mass in the right lateral recess was affecting the traversing right L5 and S1 nerve roots. Given the exclusive axial symptoms consistent with lumbar zygapophyseal joint arthropathy, the patient was treated with a repeat L3-4 medial branch and L5 dorsal ramus radiofrequency ablation and experienced subsequent near-complete pain resolution. CONCLUSIONS: Careful consideration must be taken when conducting clinical evaluation, imaging, diagnosis, and treatment of patients with low back pain given the significant frequency of abnormal, often nonconcordant, radiological findings. KEY WORDS: Pneumorrhachis, vacuum disc phenomenon, low back pain, case report

3D nerve proximity mapping of the medial branch of lumbar dorsal ramus: An anatomical study

ObjectiveLumbar medial branch (MB) radiofrequency ablation is a common intervention to treat facetogenic low back pain. Consensus among spine pain interventionalists is that the cannula tip should be placed adjacent to the periosteum of the lateral neck of the superior articular process (SAP) to ensure maximum contact with the MB. The spatial relationship of the nerve to the periosteum of the lateral neck of the SAP has not been quantified in 3D. The objectives of the current study were to: 1) use 3D modelling technology to quantify the location along the lateral neck of the SAP where the MB is in direct contact with the periosteum; and 2) identify target site(s) to optimize lumbar MB denervation. DesignSeventy lumbar dorsal rami in 14 formalin-embalmed specimens were dissected, digitized, and modeled in 3D. The 3D positional data of the MB were used to generate a novel nerve proximity map which provided a method to quantify and visualize the 3D course of the MB in relation to the periosteum of the lateral neck of SAP. The percent of the lateral neck of SAP in contact with the MB was quantified and consistent target site(s) identified. ResultsThere was variability in the percentage of the lateral neck of SAP in contact with the MB. The mean percentage of the lateral neck of SAP in contact with the MB for the L1-L5 levels ranged between 57.39 ± 10.72 % (for L1) to 81.54 ± 10.48 % (for L5). The nerve proximity map showed consistent course of the MB along the posterior portion of the lateral neck of SAP and at a novel target site distal to the mamillo-accessory notch (i.e. sub-mammillary landmark). ConclusionThe percent of the lateral neck that was in contact with the MB was quantified and visualized using a novel nerve proximity mapping methodology which may be used to inform cannula tip depth placement. Further, the nerve proximity maps were used to identify an alternative landmark to extend the length of the MB captured. The proposed sub-mammillary landmark may be a viable target site pending future anatomical and clinical investigations.

True lateral imaging during lumbar medial branch radiofrequency neurotomy: Interobserver reliability

BackgroundTrue lateral imaging (TLI), obtained by superimposing bilateral lumbar spine structures and aligning superior endplate cortical bone, requires deliberate rotational adjustments of the laterally positioned fluoroscope in both the axial and longitudinal planes. True lateral segmental imaging is necessary to depict true and accurate radiofrequency (RF) cannula positioning relative to bony anatomy during lumbar medial branch radiofrequency neurotomy (LMBRFN). ObjectiveTo determine the interobserver reliability of TLI during LMBRFN. MethodsThis was a retrospective review of a prospectively generated collection of lateral fluoroscopic images to determine the interobserver reliability of TLI during LMBRFN. Lateral fluoroscopic images were prospectively collected from 34 consecutive L4-5 and L5-S1 LMBRFN procedures during routine clinical practice. Employing International Pain and Spine Intervention Society (IPSIS) LMBRFN and TLI techniques, an RF cannula was positioned parallel to the L3 and L4 medial branches and the L5 dorsal rami. During the normal course of TLI, untrue and final true lateral segmental images were obtained and saved. An original data set of 100 pairs of true and untrue lateral images was reviewed to verify true laterality using established criteria; disagreement was resolved by consensus or discarding ambiguous cases. To measure interobserver reliability (Cohen's Kappa), two blinded expert reviewers independently reviewed the image set, identifying the true lateral image and the plane requiring correction. ResultsThe observers agreed upon 98/98 true lateral RF-segment images (Kappa score 1.0 [1.00,1.00]). The observers agreed upon 86/98 maneuvers to correct the untrue RF-segment image. The Kappa score for determining the most appropriate corrective maneuver was 0.76 (0.63,0.89), showing substantial interobserver agreement. ConclusionsThe true lateral image of the targeted RF segment during LMBRFN was reliably determined with perfect interobserver agreement. Interobserver agreement was substantial regarding the maneuver to achieve TLI.

Feasibility and Analgesic Efficacy of Thoracolumbar Dorsal Ramus Nerve Block Using Multiorifice Pain Catheters for Scoliosis Surgery: A Prospective Cohort Study.

Approximately 38,000 scoliosis surgery correction operations are performed annually in the United States; these operations are associated with considerable postoperative pain which can be difficult to manage. This is largely attributed to an incision spanning multiple vertebral segments with paraspinal muscle dissection and retraction to facilitate the implantation of segmental hardware and rods. Frequently utilized analgesic modalities include intravenous patient-controlled analgesia and epidural analgesia, often in combination. We sought to ascertain the feasibility and analgesic efficacy of continuous thoracolumbar dorsal ramus nerve (TDRN) block using surgically placed multiorifice catheters. Forty-two patients diagnosed with idiopathic scoliosis who underwent a posterior spinal fusion (PSF) were enrolled after consent was obtained. Patients were managed utilizing a standardized Enhanced Recovery After Surgery) protocol including a perioperative opioid-sparing regimen. Data were collected at specified time intervals during the recovery period. These data points included pain scores using the Numeric Rating Scale. Parenteral or both oral and parenteral opioid consumption doses were also collected every 4 hours. Any significant postoperative adverse events were recorded as well. A total of 42 patients had surgically placed TDRN catheters, and 40 patients were included in this study. The patients all reported low to moderate pain scores with low opioid consumption postoperatively, while the TDRN catheter delivery of local anesthetic analgesics did not result in significant complications. A regional technique utilizing TDRN catheters could be a valuable component of the postoperative pain management protocols for PSF surgery, and additional studies are warranted. This study evaluated the feasibility and analgesic efficacy of TDRN catheters for postoperative pain control following multilevel PSF for idiopathic scoliosis. Continuous local anesthetic delivery through TDRN catheters is a feasible and safe technique for postoperative pain control in these patients. Selective blockade of the dorsal rami might have benefits over epidural analgesia or other regional techniques.

Targeted multifidus muscle activation reduces fibrosis of multifidus muscle following intervertebral disc injury

PurposeAerobic exercise produces beneficial outcomes in patients with low back pain and partially attenuates the fibrotic changes to the multifidus in a model of intervertebral disc (IVD) degeneration. More targeted exercise might be required to fully attenuate these fibrotic alterations. This study aimed to investigate whether activation of the multifidus induced by neurostimulation could reduce fibrosis of the multifidus in a model of IVD degeneration in sheep.MethodsIVD degeneration was induced in 18 merino sheep via a partial thickness unilateral annulus fibrosus lesion to the L1/2 and L3/4 IVDs. All sheep received an implantable neurostimulation device that provides stimulation of the L2 medial branch of the dorsal ramus. Three months after surgery, the animals were assigned to Injury or Activated groups. Activated animals received neurostimulation and the Injury group received no stimulation. Six months after surgery, the multifidus was harvested at L2 and L4. Van Gieson’s, Sirius Red and immunofluorescence staining for Collagen-I and -III and quantitative PCR was used to examine fibrosis. Muscle harvested from a previous study without IVD injury was used as a control.ResultsNeurostimulation of the multifidus attenuated IVD degeneration dependent increases in the connective tissue, including Collagen-I but not Collagen-III, compared to the Injury group at L4. No measures of the multifidus muscle at L2, which received no stimulation, differed between the Injury and Activated groups.ConclusionsThese data reveal that targeted activation of the multifidus muscle attenuates IVD degeneration dependent fibrotic alterations to the multifidus.

Pathways of dye spread after injections in the paraspinal spaces-A cadaveric study.

The erector spinae plane (ESP) block is the most sought-after block since its inception. However, it is more of dorsal rami block with unpredictable ventral diffusion to the paravertebral area. We injected dye in ESP and other paraspinal spaces to study and compare the dye diffusion pattern along the neuroaxis and paraspinal region in human cadavers. In six soft-embalmed cadavers (12 specimens), 20 mL methylene blue dye (erector spinae plane and paravertebral space) or indocyanine green dye (inter-ligament space) was injected bilaterally using an in-plane ultrasound-guided technique at the level of the costotransverse junction of fourth thoracic vertebrae. Dye spread was evaluated bilaterally in the coronal plane in the paravertebral and intercostal spaces from the 1st and the 12th rib. Axial and sagittal sections were performed at the level of the 4th thoracic vertebrae. After cross sections, the extent of dye spread was investigated in ESP, inter-ligament, and paravertebral spaces. The staining of the ventral and dorsal rami and spread into the intercostal spaces was evaluated. ESP injection was mainly restricted dorsal to the costotransverse foramen and did not spread anteriorly to the paravertebral space. The paravertebral injection involved the origin of the spinal nerve and spread laterally to the intercostal space. The inter-ligament space injection showed an extensive anterior and posterior dye spread involving the ventral and dorsal rami. Following ESP injection, there was no spread of the dye anteriorly to the paravertebral space and it only involved the dorsal rami. Inter-ligamentous space injection appears to be the most promising block as dye spread both anteriorly to paravertebral space and posteriorly toward ESP.

Cadaveric study of the ultrasound-guided erector spinae plane block over the transverse process of the twelfth thoracic vertebra in dogs: Transversal vs longitudinal approach

This study describes a transversal (TV) ultrasound-guided erector spinae plane (ESP) block technique over the transverse process of T12. And evaluates the distribution of the dye and affected nerves branches compared to a longitudinal (LNG) approach over the transverse process of T12 in canine cadavers. Secondly, it also compares de anatomy and dimensions of the transverse processes of T12 with T9 and T5. For this double-masked, cadaveric experimental study, 12 adult Beagle cadavers were injected with 0.6 mL/kg of dye/contrast. Spread was evaluated by computed tomography (CT) and dissection.Mean bodyweight was 9.76 (±0.59) kg. The TV and LNG approaches stained a median (range) of four (2–6) and three (1–6) medial branches of the dorsal rami of the spinal nerves, three (2–6) and three (2–5) lateral branches, and one (0−3) and one (0−4) ventral branches, respectively. Dye was detected in the epidural space in 55.6% and 66.7% of cases for the TV and LNG approaches, respectively (P=0.63). And in the ventral paravertebral compartment in 22.2% and lymphatics in 88.8% in both approaches. There were no statistical differences for the spread. The dorsolateral edge of the transverse process (TP) was not visible with CT at T12. The mean (±SD) length of the TP was significantly shorter at T12 [3.34 (±0.22)] mm, compared to T9 [6.08 (±0.47)] mm and T5 [5.93 (±0.62)] mm (P <0.001). This study showed similar distribution whether using a TV or LNG approach and differences in the anatomy and length of the T12 TP.

Investigation of the anatomical course of articular branches to the thoracic zygapophysial joints

BackgroundRecent studies have questioned the validity of targeting the thoracic medial branch via anesthetic blocks or radiofrequency neurotomy for the diagnosis or treatment of pain from the thoracic zygapophysial joints. PurposeTo define the origin and course of the articular branches to the thoracic zygapophysial joints at all levels. DesignCadaveric dissection. SettingThe Gross Anatomy Laboratory at the University of New England College of Osteopathic Medicine. SubjectsOne cadaveric thoracic spine. MethodsGross and stereoscopic dissection of the bilateral dorsal rami T1–T12 was performed on one embalmed cadaver. The medial and lateral branches were traced from their cutaneous distribution to the origin at the dorsal ramus. The articular branches were identified using stereoscopic dissection by tracing their origin from the dorsal ramus or medial branch to the capsule of the zygapophysial joint. The images were recorded using digital photography. ResultsTwenty-two of the twenty-four articular branches were identified in a single cadaveric specimen. Articular branches at T7 on the right side and T9 on the left side were not identified. 5 of the 22 (18%) articular branches were observed to arise from the proximal segment of the medial branch of the dorsal ramus. Of the remainder, 17 of the 22 (78%) articular branches were observed to arise from the dorsal primary ramus itself. At levels T1-9, the articular branch coursed inferiorly along the lamina to reach the joint capsule. At levels T10-T12, the articular branch traversed the intervertebral foramen to reach the facet joint. The T12 medial branch on the left was seen to travel inferior to innervate the L1/L2 zygapophysial joint. ConclusionThe source of the innervation for the thoracic zygapophysial is variable and can arise from the dorsal ramus itself or from the proximal segment of the medial branch. Unlike the cervical and lumbar medial branches, which innervate two joints each, in this case, the thoracic dorsal rami appear to innervate only the zygapophysial joint at the level of the nerve exit. It should be noted that the findings may be limited in their generalizability due to the reliance on a single cadaver study.

Efficacy of Bilateral Erector Spinae Block in Patients Undergoing Posterior Spine Fusion Surgeries: A Comparative Randomised Controlled Trial.

Introduction During spine surgeries, various levels of tissue injury can result in varying hemodynamic responses and significant postoperative pain. Perioperative pain management is essential to controlling hemodynamic responses and postoperative pain management. Erector spinae plane (ESP) blocks can help alleviate this pain by blocking the dorsal rami of the spinal nerve. This study aims to evaluate the efficacy of ESP by assessing the perioperative opioid requirement, hemodynamic parameters, and visual analogue score (VAS) during the postoperative period. Methods In this study, 56 patients underwent elective posterior spine fusion surgeries under conventional anaesthesia and were allocated into two groups: 28 patients were included in the conventional group (Group C) and 28 patients in the ESP group (Group E). Group C patients received 20 ml of 0.9% sodium chloride (NaCl) on each side, and Group E patients received 20 ml of 0.25% bupivacaine + 4 mg dexamethasone on each side under ultrasound sonography guidance. Postoperative pain was assessed using the VAS score. The hemodynamic parameters during the intraoperative period, the time for the first opioid analgesia requirement until 24 hours in the postoperative period, and the amount of cumulative opioid consumption during the perioperative period were observed. Results Postoperative VAS was lower in Group E (P < 0.001). There were significant differences in hemodynamic parameters: heart rate (P < 0.045), systolic blood pressure (P < 0.002), diastolic blood pressure (P < 0.003), and mean arterial pressure (P < 0.002) at the time of incision in Group E. Intraoperative opioid requirements at the time of incision (P < 0.036), 60th minutes (P < 0.023), 120th minutes (P < 0.023), and postoperative opioid requirements at the first hour (P < 0.001), sixth hour (P < 0.004), 14th hour (P < 0.025), 20th hour (P < 0.009), and 24th hour (P < 0.025) had lower opioid requirements in Group E than Group C. Conclusion ESP block is a more site-specific dorsal rami block with a better perioperative hemodynamic profile, a part of multimodal analgesia intraoperatively, and excellent postoperative analgesia with fewer postoperative opioid requirements in multilevel spine fusion surgeries.

Anatomical Observation and Clinical Significance of the Medial Branch of the Lumbar Dorsal Rami.

Anatomical study. This study aimed to elaborate on the anatomical characteristics of the medial branch of the lumbar dorsal rami and to discuss its possible clinical significance. Radiofrequency ablation targeting the medial branch of the lumbar dorsal rami has been increasingly used in the clinical management of facetogenic low back pain (FLBP). Nonetheless, attention is also being given to complications such as atrophy of the lumbar soft tissues and muscles. Therefore, a more detailed understanding of the innervation pattern on the facet joint may improve the precision of nerve ablation therapy for FLBP. An anatomical study of eight human specimens was carried out. The anatomic characteristics of the medial branch were observed and recorded. The medial branch originates from the lumbar dorsal rami, running close to the root of the posterolateral side of the superior articular process of the inferior cone. When passed through the mamillo-accessory ligament, it turns direction to the medial and caudal side, running in the multifidus muscle. In our study, each medial branch sent out two to five branches along the way. All the medial branches in L1-L4 gave off one to two small branches when crossing the facet joint and innervated the joint of the lower segment. Nineteen medial branches (23.75%) gave off recurrent branches to innervate the joint at the upper segment. The anatomical features of the medial branch remain similar in each lumbar segment. There are two types of joint branches, including the articular fibers that emanate from the medial branch as it runs along the medial border of the facet joint and the recurrent branch from the medial branch that innervates the upper facet joint. Moreover, an anastomotic branch was found in the medial branches between different segments.