[Cause analysis and clinical intervention of C 5 palsy after cervical surgery].

Objective: To review the research progress of C 5 palsy (C 5P) after cervical surgery, providing new clinical intervention ideas for the C 5P patients. Methods: The relevant literature domestically and abroad was extensively consulted and the latest developments in the incidence, risk factors, manifestations and diagnosis, prevention, and intervention measures of C 5P were systematically expounded. Results: C 5P is characterized by weakness in the C 5 nerve innervation area after cervical decompression surgery, manifested as limited shoulder abduction and elbow flexion, with an incidence rate more than 5%, often caused by segmental spinal cord injury or mechanical injury to the nerve roots. For patients with risk factors, careful operation and preventive measures can reduce the incidence of C 5P. Most of the patients can recover with conservative treatment such as drug therapy and physical therapy, while those without significant improvement after 6 months of treatment may require surgical intervention such as foraminal decompression and nerve displacement. Conclusion: Currently, there has been some advancement in the etiology and intervention of C 5P. Nevertheless, further research is imperative to assess the timing of intervention and surgical protocol.

Oligodendrocyte precursor cells stop sensory axons regenerating into the spinal cord.

Primary somatosensory axons stop regenerating as they re-enter the spinal cord, resulting in incurable sensory loss. What arrests them has remained unclear. We previously showed that axons stop by forming synaptic contacts with unknown non-neuronal cells. Here, we identified these cells in adult mice as oligodendrocyte precursor cells (OPCs). We also found that only a few axons stop regenerating by forming dystrophic endings, exclusively at the CNS:peripheral nervous system (PNS) borderline where OPCs are absent. Most axons stop in contact with a dense network of OPC processes. Live imaging, immuno-electron microscopy (immuno-EM), and OPC-dorsal root ganglia (DRG) co-culture additionally suggest that axons are rapidly immobilized by forming synapses with OPCs. Genetic OPC ablation enables many axons to continue regenerating deep into the spinal cord. We propose that sensory axons stop regenerating by encountering OPCs that induce presynaptic differentiation. Our findings identify OPCs as a major regenerative barrier that prevents intraspinal restoration of sensory circuits following spinal root injury.

Characteristics of Changes in Intrathecal Baclofen Dosage over Time due to Causative Disease.

Intrathecal baclofen (ITB) therapy effectively treats spasticity caused by brain or spinal cord lesions. However, only a few studies compare the course of treatment for different diseases. We investigated the change in daily dose of baclofen per year and its associated adverse events in patients presenting with the three most common etiologies at our institute: hereditary spastic paraplegia, cerebral palsy, and spinal cord injury. The ITB pumps were implanted from July 2007 to August 2019, with a mean follow-up period of 70 months. In patients with hereditary spastic paraplegia, baclofen dosage was reduced after eight years following ITB introduction, and the treatment was terminated in one patient owing to disease progression. In patients with cerebral palsy, the dosage increased gradually, and became constant in the 11th year. Patients with spinal cord injury gradually increased their baclofen dosage throughout the entire observation period. Severity and adverse event rates were higher in patients with cerebral palsy than in others. The degree and progression of spasticity varied depending on the causative disease. Understanding the characteristics and natural history of each disease is important when continuing ITB treatment.

Distal nerve transfer (PT-AIN, SUP-PIN) for regaining hand function in C8, T1 root injury following extirpation of the right C8, T1 schwannoma.

A 48-year-old female was admitted to the authors' department due to hand weakness as a consequence of C8, T1 root injury. Eight months earlier, the patient had been treated by a pulmonary surgeon due to an expansive lesion near the apex of the right lung, which resulted in right lower brachial plexus palsy. Postoperative pathohistological findings indicated that the lesion was nerve schwannoma. The diagnostic process included physical examination, electromyoneurography, and MRI. A distal nerve transfer (pronator teres-anterior interosseus nerve [PT-AIN], supinator-posterior interosseus nerve [SUP-PIN]) was performed in order to restore hand function. The video can be found here: https://stream.cadmore.media/r10.3171/2022.10.FOCVID22110.

How dimensions can guide surgical planning and training: a systematic review of Kambin's triangle.

OBJECTIVE: The authors sought to analyze the current literature to determine dimensional trends across the lumbar levels of Kambin's triangle, clarify the role of imaging techniques for preoperative planning, and understand the effect of inclusion of the superior articular process (SAP). This compiled knowledge of the triangle is needed to perform successful procedures, reduce nerve root injuries, and help guide surgeons in training. METHODS: The authors performed a search of multiple databases using combinations of keywords: Kambin's triangle, size, measurement, safe triangle, and bony triangle. Articles were included if their main findings included measurement of Kambin's triangle. The PubMed, Scopus, Ovid, Cochrane, Embase, and Medline databases were systematically searched for English-language articles with no time frame restrictions through July 2022. RESULTS: Eight studies comprising 132 patients or cadavers were included in the study. The mean ± SD age was 66.69 ± 9.6 years, and 53% of patients were male. Overall, the size of Kambin's triangle increased in area moving down vertebral levels, with L5-S1 being the largest (133.59 ± 4.36 mm2). This trend followed a linear regression model when SAP was kept (p = 0.008) and removed (p = 0.003). There was also a considerable increase in the size of Kambin's triangle if the SAP was removed. CONCLUSIONS: Here, the authors have provided the first reported systematic review of the literature of Kambin's triangle, its measurements at each lumbar level, and key areas of debate related to the definition of the working safe zone. These findings indicate that CT is heavily utilized for imaging of the safe zone, the area of Kambin's triangle tends to increase caudally, and variation exists between patients. Future studies should focus on using advanced imaging techniques for preoperative planning and establishing guidelines for surgeons.

Arthroscopic centralization reduces extrusion of the medial meniscus with posterior root defect in the ACL reconstructed knee.

PURPOSE: The purpose of this study was to evaluate the effects of arthroscopic meniscal centralization reinforcement for a medial meniscus (MM) posterior root defect on knee kinematics and meniscal extrusion in the anterior cruciate ligament reconstructed (ACLR) knee. The hypothesis was that the medial meniscus centralization would reduce extrusion and anterior laxity in ACLR knee with a medical meniscal defect. METHODS: Fourteen fresh-frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under the following loading conditions: (a) an 89.0 N anterior tibial load, (b) 5.0 Nm internal and external rotational torques, (c) a 10.0 Nm valgus and varus loadings, and (d) a combined 7.0 Nm valgus moment and then a 5.0 Nm internal rotation torque as a static simulated pivot shift. The tested knee states included: (1) anatomic single-bundle cruciate ligament reconstruction with intact medial meniscus (MM Intact), (2) anatomic single-bundle cruciate ligament reconstruction with medial meniscus posterior root defect (MM Defect), (3) Anatomic single-bundle cruciate ligament reconstruction with medial meniscus arthroscopic centralization (MM Centralization). Medial meniscus arthroscopic centralization was performed using 1.4 mm anchors with #2 suture. The MM extrusion (MME) was measured using ultrasound under unloaded and varus loading conditions at 0° and 30° of flexion. RESULTS: Anterior tibial translation (ATT) increased significantly with MM posterior root defect compared to MM intact at all flexion angles. With MM centralization, ATT was not significantly different from the intact meniscus at 15° and 30° of flexion. Meniscus extrusion increased significantly with the root defect compared to intact meniscus and decreased significantly with meniscal centralization compared to the root defect at both flexion angles. CONCLUSIONS: In ACL reconstruction, cases involving irreparable medial meniscal posterior root tears, applying arthroscopic centralization for avoiding the meniscal extrusion should be considered. Clinically, in ACL reconstruction cases with irreparable medial meniscal posterior root tears, applying arthroscopic meniscal centralization for avoiding the meniscal extrusion should be considered. Meniscal centralization decreases the extrusion of the MM and offers improvements in knee laxity.

Monitoring spinal surgery for extramedullary tumors and fractures.

Meningiomas are the most common intradural extramedullary tumors, followed by nerve sheath tumors that can also grow extradurally. Metastases are the most frequent extradural tumors and most commonly affect the thoracic vertebrae. Spinal fractures with column dislocation and/or instability require surgical fixation. Spine surgery for an extramedullary tumor or fracture usually involves decompression of neural elements and instrumentation for stabilization. These procedures risk spinal cord and nerve root injury. The incidence of nerve root deficits after resection of nerve sheath tumors is particularly high since the tumor grows from the rootlets. Intraoperative neurophysiologic monitoring and mapping techniques have been introduced to prevent iatrogenic neurologic deficits. These include motor and sensory evoked potentials, electromyography, compound muscle action potentials, and the bulbocavernosus reflex. The combination of techniques chosen for a particular procedure depends on the surgical level and the character of the lesion.

Diagnostic Ability of Ultrasonography in Brachial Plexus Root Injury at Different Stages Post-trauma.

Brachial plexus (BP) root injury often results in disability of the upper extremities. Improvements in high-frequency ultrasonography have enabled the visualization of BP nerve roots. This study was aimed at quantifying the diagnostic accuracy of ultrasonography in BP root injury at different stages post-trauma. A consecutive series of 170 patients with BP root injury between 2015 and 2019 were studied retrospectively and divided into three groups on the basis of time between injury and ultrasound examination (≤1 mo, 1-3 mo, >3 mo). Diagnosis of complete BP root injury under ultrasound was determined using a pre-defined criterion, including pseudomeningocele, retraction and rupture. Diagnostic accuracy was calculated based on surgical findings and intra-operative electrophysiological tests. Rates of detection of the cervical (C5-C8) and thoracic (T1) nerve roots under ultrasound were 99.4%, 99.4%, 99.4%, 95.9% and 79.4%, respectively. The sensitivity for complete BP root injury was 0.74, and the specificity was 0.91. No significant differences in sensitivity or specificity were observed across time stages. Ultrasound exhibited substantial consistency with surgical findings (κ = 0.70) for complete BP root injury at any stage post-injury. Ultrasound can be an optional method of diagnosis of complete BP root injury at an early stage post-injury.

Stretch on the L5 nerve root in high-grade spondylolisthesis reduction.

OBJECTIVE: L5 nerve root (L5-NR) injury after surgery for high-grade spondylolisthesis (HGS) was considered a nerve stretch associated with reduction. Currently, however, no study has directly measured the stretch on the L5-NR during HGS reduction procedures. METHODS: CT data of 4 patients with mild lumbar degeneration (control group [CG]) and 4 patients with HGS (spondylolisthesis group [SG]) were used for 3D printing to develop L5 vertebrae and sacrum models. These models were mounted on a self-designed reduction apparatus, which performed vertical translation (disc heights of 0, 5, and 10 mm), anterior-posterior translation (reduction, 0%-100%), and slip-angle correction (0° to -30°). The L5-NR was simulated by using a rabbit sciatic nerve. The cephalic side of the nerve was fixed at the upper base of the L5 pedicle, while the caudal side was connected to a high-precision sensor and an indicator to measure the tension (stretch) on the nerve during the reduction procedures in real time. RESULTS: The SG had shorter L5-NRs than the CG. At a 0-mm disc height, the peak tension on the L5-NR changed from 0 N (reduction 0%) to 1.81 ± 0.54 N (reduction 100%) in the SG and to 1.78 ± 0.71 N in the CG. At a 10-mm disc height, the tension changed from 1.50 ± 0.67 N to 4.97 ± 1.04 N in the SG and from 0.92 ± 0.45 N to 3.26 ± 0.88 N in the CG. In both the CG and SG, at the same disc height, all values from the complete reduction process were statistically significant. Furthermore, at the same degree of reduction, the comparisons between different disc heights were almost all statistically significant. Intergroup comparisons showed that an increased disc height would cause more tension on the L5-NR in the SG than in the CG. At a 10-mm disc height, all results between the groups demonstrated statistical significance. The slip-angle correction produced a slight increase in the tension on the L5-NR in both groups. CONCLUSIONS: Increased disc height and reduction significantly increased the tension on the L5-NR, which demonstrated a nonlinear curve. The slip-angle correction from 0° to -30° slightly increased the tension on the L5-NR. Under the same degree of reduction and restored disc height, the SG had more tension on the L5-NR than the CG.

Diagnostic performance of preoperative ultrasound for traumatic brachial plexus root injury: A comparison study with an electrophysiology study.

Purpose: Accurate preoperative assessment for traumatic brachial plexus injury (BPI) is critical for clinicians to establish a treatment plan. The objective of this study was to investigate the diagnostic performance of preoperative ultrasound (US) through comparison with an electrophysiology study (EPS) in the assessment of traumatic brachial plexus (BP) root injury. Materials and methods: We performed a retrospective study in patients with traumatic BPI who had preoperative US and EPS, excluding obstetric palsy and other nontraumatic neuropathies. US examination was performed on an EPIQ 5 color Doppler equipment. EPS was performed on a Keypoint 9033A07 Electromyograph/Evoked Potentials Equipment, testing electromyography (EMG), nerve conduction studies (NCS), and somatosensory evoked potentials (SEP). Each BP root of all patients was assessed by US and EPS as completely injured or incompletely injured, respectively. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated based on the correlation with intraoperative findings. The accuracy of US and EPS were compared using the McNemar test. The added benefit of US was evaluated by comparing the sensitivity and specificity between the combined tests with EPS using the McNemar test. Results: This study included 49 patients with traumatic BPI who underwent BP surgeries from October 2018 to September 2022. Surgical exploration confirmed 89 completely injured BP roots in 28 patients. US correctly detected 80 completely injured BP roots (sensitivity, 0.899; specificity, 0.981; PPV, 0.964; NPV, 0.944; accuracy, 0.951). EPS correctly detected 75 completely injured BP roots (sensitivity, 0.843; specificity, 0.929; PPV, 0.872; NPV, 0.912; accuracy, 0.898). US showed significantly higher accuracy than EPS (p = 0.03). When combining US and EPS for completely injured BP root detection, the sensitivity of the inclusive combination (0.966) was significantly higher than EPS alone (p = 0.000977), and the specificity of the exclusive combination (1.000) was significantly higher than EPS alone (p = 0.000977). Conclusion: Preoperative US is an effective diagnostic tool in the assessment of traumatic BP root injury. US had higher accuracy than EPS in this study. Sensitivity and specificity were significantly higher than EPS when US was combined with EPS.

Inhibiting spinal secretory phospholipase A2 after painful nerve root injury attenuates established pain and spinal neuronal hyperexcitability by altering spinal glutamatergic signaling.

Neuropathic injury is accompanied by chronic inflammation contributing to the onset and maintenance of pain after an initial insult. In addition to their roles in promoting immune cell activation, inflammatory mediators like secretory phospholipase A2 (sPLA2) modulate nociceptive and excitatory neuronal signaling during the initiation of pain through hydrolytic activity. Despite having a known role in glial activation and cytokine release, it is unknown if sPLA2 contributes to the maintenance of painful neuropathy and spinal hyperexcitability later after neural injury. Using a well-established model of painful nerve root compression, this study investigated if inhibiting spinal sPLA2 7 days after painful injury modulates the behavioral sensitivity and/or spinal dorsal horn excitability that is typically evident. The effects of sPLA2 inhibition on altered spinal glutamatergic signaling was also probed by measuring spinal intracellular glutamate levels and spinal glutamate transporter (GLAST and GLT1) and receptor (mGluR5, GluR1, and NR1) expression. Spinal sPLA2 inhibition at day 7 abolishes behavioral sensitivity, reduces both evoked and spontaneous neuronal firing in the spinal cord, and restores the distribution of neuronal phenotypes to those of control conditions. Inhibiting spinal sPLA2 also increases intracellular glutamate concentrations and restores spinal expression of GLAST, GLT1, mGluR5, and GluR1 to uninjured expression with no effect on NR1. These findings establish a role for spinal sPLA2 in maintaining pain and central sensitization after neural injury and suggest this may be via exacerbating glutamate excitotoxicity in the spinal cord.

The consequences and outcomes associated with dental implants encroaching on adjacent teeth.

BACKGROUND: Dental implant placement carries a risk of iatrogenic damage to adjacent root surfaces. PURPOSE: To classify and understand different types of trauma to the tooth root body by dental implants. MATERIALS AND METHODS: This prospective case series included 43 implants placed between February 2017 and June 2020 that had primary stability and were in a position that accidentally invaded the adjacent teeth. The type and degree of the injury were evaluated clinically and radiographically. Tenderness, mobility, and sensitivity tests of the injured teeth were conducted at different visits. Implant failure was confirmed by the presence of implant mobility during the healing period. RESULTS: Overall, 43 patients had root injuries due to dental implant surgeries. Regarding the 43 injured roots, 32 developed transient tenderness to percussion, 16 developed variable degrees of resorption in the cementum, three lost pulp sensitivity and one had persistent tenderness to percussion. No injured teeth were lost. In three patients, implant periapical lesions were confirmed radiographically as radiolucency near the apex of the involved implants. Out of the 43 implants, 11 failed and were removed within 6 months, with an implant failure rate of (25%). CONCLUSIONS: Root damage after implant surgery varies depending on the type and severity of injury. Periodic clinical and radiographical examination is necessary to monitor root resorption and implant integration and to rule out pulp necrosis.

Neuroprotective Effects of Sigma 1 Receptor Ligands on Motoneuron Death after Spinal Root Injury in Mice.

Loss of motor neurons (MNs) after spinal root injury is a drawback limiting the recovery after palliative surgery by nerve or muscle transfers. Research based on preventing MN death is a hallmark to improve the perspectives of recovery following severe nerve injuries. Sigma-1 receptor (Sig-1R) is a protein highly expressed in MNs, proposed as neuroprotective target for ameliorating MN degenerative conditions. Here, we used a model of L4-L5 rhizotomy in adult mice to induce MN degeneration and to evaluate the neuroprotective role of Sig-1R ligands (PRE-084, SA4503 and BD1063). Lumbar spinal cord was collected at 7, 14, 28 and 42 days post-injury (dpi) for immunohistochemistry, immunofluorescence and Western blot analyses. This proximal axotomy at the immediate postganglionic level resulted in significant death, up to 40% of spinal MNs at 42 days after injury and showed markedly increased glial reactivity. Sig-1R ligands PRE-084, SA4503 and BD1063 reduced MN loss by about 20%, associated to modulation of endoplasmic reticulum stress markers IRE1α and XBP1. These pathways are Sig-1R specific since they were not produced in Sig-1R knockout mice. These findings suggest that Sig-1R is a promising target for the treatment of MN cell death after neural injuries.

Co-targeting myelin inhibitors and CSPGs markedly enhances regeneration of GDNF-stimulated, but not conditioning-lesioned, sensory axons into the spinal cord.

A major barrier to intraspinal regeneration after dorsal root (DR) injury is the DR entry zone (DREZ), the CNS/PNS interface. DR axons stop regenerating at the DREZ, even if regenerative capacity is increased by a nerve conditioning lesion. This potent blockade has long been attributed to myelin-associated inhibitors and (CSPGs), but incomplete lesions and conflicting reports have prevented conclusive agreement. Here, we evaluated DR regeneration in mice using novel strategies to facilitate complete lesions and analyses, selective tracing of proprioceptive and mechanoreceptive axons, and the first simultaneous targeting of Nogo/Reticulon-4, MAG, OMgp, CSPGs, and GDNF. Co-eliminating myelin inhibitors and CSPGs elicited regeneration of only a few conditioning-lesioned DR axons across the DREZ. Their absence, however, markedly and synergistically enhanced regeneration of GDNF-stimulated axons, highlighting the importance of sufficiently elevating intrinsic growth capacity. We also conclude that myelin inhibitors and CSPGs are not the primary mechanism stopping axons at the DREZ.

Smash ridge tillage strongly influence soil functionality, physiology and rice yield.

The practice of smash-ridging on dry land crop cultivation has shown much promise. However, the mechanism how does soil functionality and root traits can affect rice yield under smash ridge tillage with reduced nitrogen fertilization have not yet been explored. To fill this knowledge gap, we used three tillage methods-smash-ridging 40 cm (S40), smash-ridging 20 cm (S20), and traditional turn-over plowing 20 cm (T)-and two rice varieties (hybrid rice and conventional rice) and measured soil quality, root traits, rice yield and their correlation analysis at different growth stages. Soil physical and chemical properties were significantly improved by smash-ridging, including improvements in root morphological and physiological traits during three growth stages compared with T. S40 had the highest leaf area index (LAI), plant height (PH), and biomass accumulation (BA). Increment in biomass and panicle number (PN) resulted in higher grain yield (GY) of 6.9-9.4% compared with T. Correlation analysis revealed that root total absorption area (RTAA), root active absorption area (RAA), and root area ratio (RAR) were strongly correlated with soil quality. Root injury flow (RIF) and root biomass accumulation (RBA) were strongly correlated with LAI and above-ground plant biomass accumulation (AGBA). Conclusively, S40 is a promising option for improving soil quality, root traits, and consequently GY.

L5 nerve root injury caused by anterolateral malpositioning of loosened S1 pedicle screws: illustrative cases.

BACKGROUND: Although malpositioning of pedicle screws into the spinal canal and intervertebral foramen can cause spinal nerve root injuries, there are few reports of L5 nerve root injuries when S1 pedicle screws have been inserted anterolaterally. The authors report two cases of L5 nerve root injury caused by anterolateral malpositioning of loosened S1 pedicle screws. OBSERVATIONS: In both patients, S1 pedicle screws were inserted toward the outside of the S1 anterior foramen, and the tip of the screws perforated the anterior sacral cortex. L5 nerve root impairment was not observed immediately after surgery. However, severe leg pain in the L5 area was observed after the S1 pedicle screws became loosened. In case 1, the symptoms could not be controlled with conservative treatment. Reoperation was performed 3 months after the initial surgery. In case 2, the symptoms gradually improved with conservative treatment because the area around the loosened S1 screw was surrounded by newly formed bone that stabilized the screws, as observed with computed tomography 1 year after surgery. LESSONS: Surgeons should recognize that anterolateral malpositioning of S1 pedicle screws can cause L5 nerve root injury. The screws should be inserted in the correct direction without loosening.

Percutaneous Transforaminal Endoscopic Removal of Spinal Shrapnel.

BACKGROUND: Gunshot injuries are one of the most common causes of the penetrating injuries of the spine. The victims of these injuries usually have neurologic deficits. Percutaneous endoscopic lumbar surgery is one of the most popular surgical spine interventions. We report a case with incomplete radiculopathy due to shrapnel located in L5 foramen that was removed by percutaneous endoscopic technique. CASE DESCRIPTION: A 23-year-old man sustaining a gunshot injury penetrating to the abdomen presented to our hospital. His first examination revealed a single gunshot wound with entry hole in the left low lumbar region without exit hole and right lower abdominal quadrant tenderness. Plain radiographs and computed tomography showed a bullet in the abdomen and left L5 transverse process fracture and shrapnel in L5 foraminal zone. The bullet was removed by abdominal surgeons without any surgical plan for the shrapnel in the foramen. He was referred to our clinic 3 weeks after discharge. Without any further neurologic deterioration, he had uninterrupted severe pain that was mostly unbearable during the night. Despite gradually increasing dosages of different drugs, his pain relief was insufficient. Percutaneous transforaminal endoscopic removal of the shrapnel was planned. CONCLUSIONS: Despite the absence of a universally approved algorithm in the treatment of spinal gunshot injuries, endoscopic technique can be kept in mind for a minimal access and invasiveness in case of indication for removal. With experience in endoscopic procedures and familiarity with surgical anatomy, the treatment of this unique case was completed successfully.