Factors influencing slippage after microsurgical single level lumbar spinal decompression surgery - Are the psoas and multifidus muscles involved?

PURPOSE: Patients with lumbar spinal stenosis (LSS) require microsurgical decompression (MSD) surgery; however, MSD is often associated with postoperative instability at the operated level. Paraspinal muscles support the spinal column; lately, paraspinal volume has been used as a good indicator of sarcopenia. This study aimed to determine preoperative radiological factors, including paraspinal muscle volume, associated with postoperative slippage progression after MSD in LSS patients. METHODS: Patients undergoing single-level (L3/4 or L4/5) MSD for symptomatic LSS and followed-up for ≥ 5 years in our institute were reviewed retrospectively to measure preoperative imaging parameters focused on the operated level. Paraspinal muscle volumes (psoas muscle index [PMI] and multifidus muscle index [MFMI]) defined using the total cross-sectional area of each muscle/L3 vertebral body area in the preoperative lumbar axial CT) were calculated. Postoperative slippage in the form of static translation (ST) ≥ 2 mm was assessed on the last follow-up X-ray. RESULTS: We included 95 patients with average age and follow-up periods of 69 ± 8.2 years and 7.51 ± 2.58 years, respectively. PMI and MFMI were significantly correlated with age and significantly larger in male patients. Female sex, preoperative ST, dynamic translation, sagittal rotation angle, facet angle, pelvic incidence, lumbar lordosis, and PMI were correlated with long-term postoperative worsening of ST. However, as per multivariate analysis, no independent factor was associated with postoperative slippage progression. CONCLUSION: Lower preoperative psoas muscle volume in LSS patients is an important predictive factor of postoperative slippage progression at the operated level after MSD. The predictors for postoperative slippage progression are multifactorial; however, a well-structured postoperative exercise regimen involving psoas muscle strengthening may be beneficial in LSS patients after MSD.

Correlation between inflammatory cytokine expression in paraspinal tissues and severity of disc degeneration in individuals with lumbar disc herniation.

PURPOSE: Previous animal studies have discovered dysregulation of the local inflammatory state as a novel mechanism to explain structural changes in paraspinal muscles in association with disc degeneration. This study aimed to determine whether the expression of inflammatory genes in the multifidus muscle (MM) differs between individuals with disc degeneration and non-degeneration, which may cause changes in the cross-sectional area (CSA) of paraspinal muscles and clinical outcomes. METHODS: Muscles were procured from 60 individuals undergoing percutaneous endoscopic lumbar discectomy for lumbar disc herniation (LDH). Total and functional CSAs and fatty degeneration of paraspinal muscles on ipsilateral and unilateral sides were measured. Gene expression was quantified using qPCR assays. Paired t-test and Pearson's correlation analysis were used to compare the mean difference and associations, respectively. RESULTS: There were significant differences in total CSAs of paraspinal muscles and functional CSA and fatty degeneration of MM between ipsilateral and unilateral sides. Participants in the disc degeneration group displayed higher fat infiltration in MM. The expression of TNF was moderately correlated with total CSAs of paraspinal muscles and functional CSA and fatty degeneration of MM. The expression of IL-1ß was strongly correlated with the total and functional CSA of MM. The expression of TGF-ß1 was moderately correlated with the functional CSA of MM. The expression of TNF, IL-1ß, and TGF-ß1 was moderate to strongly correlated with clinical outcomes. CONCLUSION: The results show that there were differences in the characteristics of paraspinal muscles between the ipsilateral and unilateral sides, which were affected by disc degeneration and the degree of fat infiltration. High-fat filtration and reduction of CSA of MM are associated with inflammatory dysfunction. There was evidence of a dysregulated inflammatory profile in MM in individuals with poor clinical outcomes.

THE COMPARATIVE EFFECTIVENESS OF ERECTOR SPINE PLANE BLOCK AND PARAVERTEBRAL BLOCK FOR EARLY REHABILITATION AFTER TOTAL HIP ARTHROPLASTY.

OBJECTIVE: The aim: To evaluate the effectiveness of erector spine plane block vs lumbar paravertebral block for early rehabilitation after total hip arthroplasty. PATIENTS AND METHODS: Materials and methods: The study included 60 ASA ІΙ-ΙΙΙ patients (female/male = 35/25) aged 41-82 years, undergone total hip arthroplasty under spinal anesthesia. The patients randomly divided into two groups (n=30 in each) according to postoperative regional analgesia technique: paravertebral block (PVB) and erector spine plane block (ESPB). The time interval to meet three criteria: adequate analgesia (<4 points of VAS), opioid-free period longer than 12 h, and possibility to cover walking 30 m distance without time restriction was analyzed. We also analyzed opioid requirement postoperatively. RESULTS: Results: The time interval to meet the three criteria after surgery was shorter to 9.4 h for patients in PVB group 36.3 h 95% CI 31.8 to 40.8 h than for patients in ESPB group 45.7 h 95% CI 40.1 to 51.3 h, (p = 0.016). During the first 24 h after surgery the total dose of nalbuphine per patient was significantly higher in ESPB group (10.7 95% CI 7.0 to 14.3) compared to PVB group (6.3 95% CI 3.7 to 9.0). CONCLUSION: Conclusions: The paravertebral block and erector spine plane block provide quite effective pain relieve in patients undergone total hip arthroplasty (<4 points of VAS). PVB has more opioid-preserving effect than ESPB. The paravertebral block is superior to erector spine plane block for early rehabilitation after total hip arthroplasty (the time required for patients to meet the three criteria was shorter PVB than ESPB).

Expanding Role of the Erector Spinae Plane Block for Postoperative and Chronic Pain Management.

PURPOSE OF REVIEW: The erector spinae plane block (ESPB), first described in 2016, offers the promise of becoming a safe, less invasive, and technically less demanding alternative to conventional thoracic regional anesthetic techniques including thoracic epidurals and traditional paravertebral blocks. Clinical and cadaveric studies suggest that ESPB acts on the ventral rami of spinal nerves in the paravertebral space via penetration of the intertransverse connection tissues and moreover achieves visceral analgesia via the rami communicantes and sympathetic chain. RECENT FINDINGS: The block has garnered considerable appeal related to an inherently lower risk of neurovascular and pleural injury, low risk of local anesthetic systemic toxicity, and relative technical simplicity in comparison with epidural or paravertebral blockade. It has been utilized in the treatment of acute perioperative pain in a variety of clinical applications including breast, thoracic, and abdominal surgeries and trauma and may even offer some benefit in spine surgery. Given the combination of its efficacy and decreased associated risk when performed for perioperative pain, use of ESPB should be further explored for the management of chronic pain. Current literature at this time is limited to case studies and series performed by select groups. Though it is important to consider ESPB for chronic pain, further studies are needed to evaluate the efficacy and safety of the ESPB in the management of both acute and chronic pain.

Feasibility, accuracy and safety of a percutaneous fine-needle biopsy technique to obtain qualitative muscle samples of the lumbar multifidus and erector spinae muscle in persons with low back pain.

The lumbar muscular system, in particular the lumbar multifidus muscle (LM) and the erector spinae muscle (ES), plays an important role in stabilizing and mobilizing the lumbar spine. Based on the topography, the lumbar paraspinal muscles can be classified into local and global muscles. LM is part of the local system, whereas ES is part of the global system. Therefore, it is interesting to investigate the muscle fibre type composition in both muscles. There is accumulating evidence that nonspecific chronic low back pain is associated with lumbar muscle dysfunction. To further elucidate this lumbar paraspinal muscle dysfunction, it is important to understand the structural characteristics of individual muscle fibres of LM and ES. Muscle fibre type composition can be investigated in muscle tissue samples. So far, muscle samples are taken by using invasive procedures that are not well tolerated. The aim of this article was to evaluate the feasibility, accuracy and safety of a percutaneous fine-needle biopsy technique to obtain muscle samples from LM and ES in persons with nonspecific chronic low back pain and to evaluate the feasibility of performing immunofluorescence analysis of myosin heavy chain isoform expression to investigate muscle fibre type composition. Preliminary investigations in cadavers were performed to determine the optimal vertebral level and puncture site to obtain muscle samples of LM and ES through a single skin puncture. In 15 persons with nonspecific chronic low back pain, muscle samples of LM and ES were taken under local anaesthesia with the percutaneous fine-needle biopsy technique, preceded by determination of the puncture site with ultrasonography. Muscle fibre type composition was investigated using immunofluorescence analysis of myosin heavy chain expression. The subjects reported little or no pain and were willing to repeat the procedure. The obtained muscle tissue contained transverse-sectioned muscle fibres in which muscle fibre contractile characteristics of the paraspinal muscles could be evaluated with immunofluorescence analysis of the myosin heavy chains. We can conclude that percutaneous microbiopsy appears to be feasible and accurate, and safe to use to obtain muscle tissue from the paraspinal muscles. The use of ultrasonography to determine the puncture site is necessary to ensure biopsy of the correct muscles and to ensure the safety of the procedure.

Comparative study of the paraspinal muscles after OVF between the insufficient union and sufficient union using MRI.

BACKGROUND: Identification of poor prognostic factors for OVF is important but has not yet been clearly established. Despite paraspinal muscles could play an important role in the etiology of OVF, what influence time-dependent changes in paraspinal muscles have after OVF, and the impact on conservative treatments for patients who have an OVF remain largely unknown. The purposes of this study were to (1) evaluate time-dependent changes of the paraspinal musculature using MRI after injury in patients with osteoporotic vertebral fractures (OVFs), and (2) compare paraspinal muscles between conservatively treated patients with OVF who have successful union and those failed to conservative treatment. METHODS: A total of 115 consecutive patients who had sustained a recent OVF injury in the thoracolumbar region were assessed for eligibility using medical records and all required data were available from 90 patients who had been followed up for at least 6 months. Patients who needed to undergo surgery and patients who were diagnosed as having insufficient union after 6 months of follow-up were assigned to a group with insufficient union. Lumbar trunk parameters, relative cross-sectional area (rCSA) and proportion of fat infiltration (FI%) were calculated from MRI. To evaluate the time-dependent changes in the paraspinal muscle in patients after OVF injury, correlations between the timing of MRI and rCSA, FI% were determined. To clarify the impact of paraspinal muscles on the outcome of conservative treatments of patients with OVF, we compared rCSA between the groups. RESULTS: Sixty-five patients were assigned to a group with insufficient union and 25 patients were assigned to a group with successful union. FI% of the multifidus and erector spinae in the group with insufficient union were significantly greater than in the group with union. The timing of MRI in relation to initial injury was significantly correlated with FI% of the multifidus and erector spinae. rCSA of the erector spinae was significantly larger in the group with successful union than in the group with insufficient union. CONCLUSIONS: These findings indicated a time-dependent increase of fatty degeneration of the multifidus and erector muscles, but no change in the rCSA and larger rCSAs of spinal erectors may play a role in successful union in patients with OVF.

Minimally invasive approach to resection of paraspinal schwannoma.

In this video, the authors demonstrate a minimally invasive approach and resection of a paraspinal schwannoma. Using an expandable retractor, the authors were able to identify important adjacent bony landmarks and hence visualize and remove this peripheral nerve sheath tumor. While a tubular retractor is commonly used for interbody fusion procedures, the location of the tumor allowed this minimally invasive approach resulting in excellent access, minimal soft-tissue injury, and a short hospital stay. The authors present this approach as a less invasive and yet effective technique for resection of otherwise difficult-to-access nerve lesions. The video can be found here: https://youtu.be/89OY5wdMB_k .

Laparoscopic sacrocolpopexy versus vaginal sacrospinous fixation for vaginal vault prolapse, a randomized controlled trial: SALTO-2 trial, study protocol.

BACKGROUND: Hysterectomy is one of the most performed surgical procedures during lifetime. Almost 10 % of women who have had a hysterectomy because of prolapse symptoms, will visit a gynaecologist for a surgical correction of a vaginal vault prolapse thereafter. Vaginal vault prolapse can be corrected by many different surgical procedures. A Cochrane review comparing abdominal sacrocolpopexy to vaginal sacrospinous fixation considered the open abdominal procedure as the treatment of first choice for prolapse of the vaginal vault, although operation time and hospital stay is longer. Literature also shows that hospital stay and blood loss are less after a laparoscopic sacrocolpopexy compared to the abdominal technique. To date, it is unclear which of these techniques leads to the best operative result and the highest patient satisfaction. Prospective trials comparing vaginal sacrospinous fixation and laparoscopic sacrocolpopexy are lacking. The aim of this randomized trial is to compare the disease specific quality of life of the vaginal sacrospinous fixation and laparoscopic sacrocolpopexy as the treatment of vaginal vault prolapse. METHODS: We will perform a multicentre prospective randomized controlled trial. Women with a post-hysterectomy symptomatic, POP-Q stage ≥2, vaginal vault prolapse will be included. Participants will be randomized to the vaginal sacrospinous fixation group or the laparoscopic sacrocolpopexy group. Primary outcome is disease specific quality of life at 12 months follow-up. Secondary outcome will be the effect of the surgical treatment on prolapse related symptoms, sexual functioning, procedure related morbidity, hospital stay, post-operative recovery, anatomical results using the POP-Q classification after one and 5 years follow-up, type and number of re-interventions, costs and cost-effectiveness. Analysis will be performed according to the intention to treat principle and not as a per protocol analysis. With a power of 90% and a level of 0.05, the calculated sample size necessary is 96 patients. Taking into account 10% attrition, a number of 106 patients (53 in each arm) will be included. DISCUSSION: The SALTO-2 trial is a randomized controlled multicentre trial to evaluate whether the laparoscopic sacrocolpopexy or vaginal sacrospinous fixation is the first-choice surgical treatment in patients with a stage ≥2 vault prolapse. TRIAL REGISTRATION: Netherlands Trial Register (NTR): NTR3977 ; Registered 28 April 2013.

Displacement of a Broken Dental Injection Needle Into the Perivertebral Space.

Dental injection needle breakage is an uncommon problem in dental practice. Displacement of the broken fragment into anatomical spaces is, on the other hand, a serious complication that occurs most commonly during inferior alveolar nerve blocks as a result of material wear, incorrect application of the anesthesia technique, or sudden movement of the patient during injection. Further complications such as infection, trismus, and nerve paralysis may exacerbate the condition and, if not treated adequately, life-threatening conditions may develop over time as the fragment dislodges deeper in soft tissues. Clinical symptoms of the patient, as well as the findings gathered from detailed physical examination and radiographic evaluation, are important factors to consider before performing an exploratory surgery. Removal of a broken needle may be troublesome due to its proximity to vital anatomic structures. Multislice computed tomography is a reliable imaging modality that provides accurate information to pinpoint the exact location of the needle fragment.This report describes a case of needle breakage occurred during inferior alveolar nerve block which was performed to extract a third molar tooth and the migration of the broken fragment from the right mandibular ramus area into the perivertebral space, with special emphasis on the surgical retrieval technique with multiplanar computed tomography imaging guidance.

Intramuscular Lipoma-Induced Occipital Neuralgia on the Lesser Occipital Nerve.

Occipital neuralgia (ON) is commonly characterized by a neuralgiform headache accompanied by a paroxysmal burning sensation in the dermatome area of the greater, lesser, or third occipital nerve. The authors report a rare case of ON caused by an intramuscular lipoma originating from the lesser occipital nerve.A 52-year-old man presented with sharp pain in the left postauricular area with a 3 × 2-cm palpable mass. Computed tomography revealed a mass suspiciously resembling an intramuscular lipoma within splenius muscle. In the operation field, a protruding mass causing stretching of the lesser occipital nerve was found. After complete resection, the neuralgiform headache symptom had resolved and the intramuscular lipoma was confirmed through histopathology.Previous studies on the causes of ON have reported that variation in normal anatomic structures results in nerve compression. Occipital neuralgia, however, caused by intramuscular lipomas in splenius muscles have not been previously reported, and the dramatic resolution following surgery makes it an interesting case worth reporting.

The severity of operative invasion to the posterior muscular-ligament complex influences cervical sagittal balance after open-door laminoplasty.

PURPOSE: The aim of this study was to investigate how the severity of operative invasion to the posterior muscular-ligament complex impacts postoperative cervical sagittal balance. MATERIALS AND METHODS: Ninety cases of open-door expansive laminoplasty due to cervical spondylotic myelopathy were reviewed. Fifty-three patients underwent laminoplasty with unilateral preservation of the muscular-ligament complex (unilateral elevation group). Thirty-seven patients underwent traditional open-door laminoplasty (bilateral elevation group). Preoperative and postoperative cervical sagittal parameters, including C2-C7 sagittal vertical axis (SVA), C0-2 Cobb angle and T1 slope, were compared. The cervical curvature, range of motion (ROM) and JOA score were also compared. RESULTS: The average follow-up time was 16.7 months (range 3-40 months). C2-C7 SVA significantly increased in the bilateral elevation group (+4.9 mm, P = 0.005) but remained unchanged in the unilateral elevation group (-0.2 mm, P = 0.414). The C0-2 Cobb angle increased in both groups (+4.1°, P < 0.001; +2.5°, P = 0.002). The T1 slope also increased in both groups (+1.1°, P = 0.015; +0.7°, P = 0.042). The postoperative C3-C7 curvature significantly decreased in the bilateral elevation group (-4.1°, P < 0.001). The C3-C7 ROM decreased in both groups (-17.9°, P < 0.001; -15.1°, P < 0.001). C2-C7 SVA was positively correlated with the T1 slope (Pearson = 0.468, P < 0.001) and negatively correlated with the C3-C7 curvature (Pearson = -0.322, P = 0.001). The C0-2 Cobb angle was positively correlated with C2-C7 SVA (Pearson = 0.303, P = 0.004) and negatively correlated with the C3-C7 curvature (Pearson = -0.362, P < 0.001). There was no significant between-group difference in the JOA improvement rate. CONCLUSIONS: Open-door laminoplasty significantly affected postoperative cervical sagittal balance, with the cervical vertebra appearing to tilt forward. As the severity of surgical invasion to the posterior muscular-ligament complex increased, the loss of cervical sagittal balance also increased.

Two-Level Circumferential Lumbar Fusion Comparing Midline and Paraspinal Posterior Approach: 5-Year Interim Outcomes of a Randomized, Blinded, Prospective Study.

STUDY DESIGN: A prospective randomized and blinded comparative study of 2 patient groups with >5-year follow-up. OBJECTIVE: To compare the clinical outcomes and postoperative posterior muscle changes in patients with advanced degenerative disk disease undergoing 2-level circumferential spinal fusion using a posterior midline versus a paraspinal approach. SUMMARY OF BACKGROUND DATA: Lumbar spinal fusion is often performed using a circumferential (anterior and posterior) technique. Paraspinal muscle alterations occur during the retraction of the muscles required for posterior instrumentation and fusion bed preparation, which may adversely affect outcomes. METHODS: Patients with advanced 2-level lumbar degenerative disk disease were randomized into 2 groups of 25 each for the approach to the posterior spine for their anterior-posterior fusion. A midline posterior skin incision was universal, but all patients were blinded to the fascial incision and exposure to the posterior spine. All had intertransverse and facet joint fusions with pedicle screw instrumentation. Outcomes (visual analog back and leg pain scale, pain drawing, Oswestry disability index, and self-assessment of procedure success) were assessed at various periods postoperatively. Preoperative and >1-year postoperative magnetic resonance images (MRI), including paraspinal muscles, were read by a radiologist who was blinded to the surgical approach and outcomes. RESULTS: No difference in operative time, blood loss, implant costs, or any other intraoperative parameter existed between the 2 patient groups. Although clinical improvement for all outcome scales was significant for both groups postoperatively, there was no difference between groups. Postoperative MRI T2 relaxation values were significantly increased at the operative levels and distally, but the changes were similar for both groups. CONCLUSIONS: Midline and paraspinal approaches result in similar outcomes in 2-level spinal fusions. We were unable to demonstrate that a paraspinal muscle-splitting approach to 2-level fusion was superior to the muscle-stripping midline approach. However, the study has low statistical power.

Myofascial Closure of Intradural Inclusion Cysts following in utero Myelomeningocele Repair.

Myelomeningocele is one of the most common congenital malformations. A randomized controlled trial, known as the Management of Myelomeningocele Study (MOMS), demonstrated that closure during the fetal period can be performed relatively safely and be of significant benefit to patients. However, postnatally, patients can develop resultant symptoms from a tethered cord and inclusion cysts; this often requires surgical treatment. Repeat surgery in this population can be challenging due to the age of the patients, the extent of surgical exposure needed and the need for resection of dermal and epidermal tissues in the midline. We describe our approach for closure of these complex defects using lateral fasciocutaneous flaps with relaxing incisions made in the posterior axillary line, in order to minimize tension and maximize soft tissue coverage of the midline.

[Paraspinal muscle approach with winglike working channel in the treatment of thoracic and lumbar spine fracture].

OBJECTIVE: To evaluate the clinical and radiological efficacy of paraspinal muscle approach with winglike working channel in the treatment of thoracic and lumbar spine fracture. METHODS: From October 2010 to August 2012, a total of 51 patients with thoracic and lumbar spine fractures without neurological symptoms were enrolled in the study, including 32 males and 19 females. All patients were divided into two groups: 26 patients were treated through posterior paraspinal muscle approach with winglike working channel, and 25 patients were treated through traditional posterior approach. In all patients, the interval between injury and operation was less than two weeks; the vertebral canal blocked area was less than 1/3 in sagittal diameter; the compression of the fractured vertebra height was less than 2/3. And the patients with pathological fracture and severe osteoporosis were excluded. The perioperative index including operative blood loss, draining loss, operative time, postoperative bed time were recorded. The clinical results were evaluated by visual analogue scale (VAS) for back pain preoperatively, at 3 days, 3 months, the last follow-up postoperatively and modified Macnab criteria at the last follow-up. The radiological results were evaluated by sagittal Cobb angle and the anterior height of the fractured vertebra. The data of two groups were compared statistically with paired and independent t test, χ² test, Mann-Whitney U test and Wilcoxon test. RESULTS: All patients were followed up with average of 16.6 months. In the two groups, the operative blood loss was respectively (91.5 ± 36.6) ml and (209.2 ± 38.3) ml (t=-11.216, P=0.000), draining loss was (13.7±4.4) ml and (162.3 ± 56.6) ml (t=-13.352, P=0.000), postoperative bed time was (87.3 ± 11.5) hours and (118.4 ± 20.4) hours (t=-6.727, P=0.000), VAS for back pain at 3 days postoperatively was 5.5 ± 1.0 and 6.4 ± 0.8 (t=-3.304, P=0.002), also VAS at the last follow-up was 1.0 (1.0) and 2.0 (1.0) (U=191.0, P=0.008). Data above showed significant differences between the two groups.No significant differences were found in operative time, (109.0 ± 29.7) min vs. (119.2 ± 26.8) min (t=-1.283, P=0.206), and modified Macnab criteria (χ²=0.513, P=0.774) between the two groups. The anterior height of the fractured vertebra preoperatively, at 1 week and the last follow-up postoperatively of the two groups were respectively (57.2 ± 11.8)% and (55.2 ± 10.9)% (t=0.685, P=0.496), (95.2 ± 8.3)% and (95.3 ± 5.8%) (t=-0.068, P=0.946), (92.9 ± 6.7)% and (92.1 ± 5.6)% (t=0.505, P=0.615). The sagittal Cobb angles preoperatively, at 1 week and the last follow-up postoperatively of the two groups were respectively 21.0° (12.5°) and 23.0° (12.0°) (U=316.0, P=0.544), 3.0° (5.5°) and 4.0° (4.5°) (U=342.5, P=0.893), 4.0° (5.5°) and 6.0° (6.0°) (U=328.5, P=0.701). There were no significant differences of these radiological results between the two groups in the same time point. CONCLUSION: The paraspinal muscle approach with winglike working channel in the treatment of thoracic and lumbar spine fracture is an efficient surgical option which can acquire satisfactory clinical and radiological results.

Denervation and atrophy of paraspinal muscles after open lumbar interbody fusion is associated with clinical outcome--electromyographic and CT-volumetric investigation of 30 patients.

BACKGROUND: Different studies have shown that atrophy of paraspinal muscles arises after open dorsal lumbar fusion, and the reasons for this atrophy are still not yet fully clarified. This prospective study investigates the extent of atrophy of the lumbar paraspinal muscles after open lumbar interbody fusion, its possible causes, and their association with clinical outcome measures. METHODS: Thirty consecutive patients were prospectively included (13 male, 17 female, median age 60.5 years, range 33-80 years). Mono or bisegmental, posterior lumbar interbody fusion and instrumentation was performed applying a conventional, open lumbar midline approach. Clinical outcome was assessed by the Short Form (36) Health Survey (SF-36) questionnaire and visual analogue scale. Needle electromyography of paraspinal muscles was performed preoperatively, at 6 and 12 months. Serum values of creatine kinase, lactate dehydrogenase and myoglobin were determined preoperatively, at day 2 after surgery and at discharge. Paraspinal muscle volume was determined by volumetric analysis of thin-slice computed tomography scans preoperatively and 1 year after surgery. RESULTS: There was a significant increase of electromyographic denervation activity (p =0.024) and reduced recruitment of motor units (p = 0.001) after 1 year. Laboratory studies showed a significant increase of CK (p < 0.001) and myoglobin (p < 0.001) serum levels at day 2 after surgery. The paraspinal muscle volume decreased from 67.8 to 60.4 % (p < 0.001) after 1 year. Correlation analyses revealed a significant negative correlation between denervation and muscle volume (K = -0.219, p = 0.002). Paraspinal muscle volume is significantly correlated with physical outcome (K = 0.169, p = 0.020), mental outcome (K = 0.214, p = 0.003), and pain (K = 0.382, p < 0.001) after 1 year. CONCLUSIONS: Atrophy of paraspinal muscles after open, posterior lumbar interbody fusion seems to be associated with denervation, as well as direct muscle trauma during surgery. While muscle atrophy is also correlated with a worse clinical outcome, it seems to be a determining factor for successful lumbar spine surgery.

The options of the three different surgical approaches for the treatment of Denis type A and B thoracolumbar burst fracture.

Thoracolumbar fracture is a common traumatic condition; however, the management remains challenging. The aim of this study is to establish criteria for selection of the anterior, posterior and posterolateral approaches for open reduction and internal fixation of thoracolumbar fracture. A group of 64 patients with Denis type A and B thoracolumbar burst fracture were treated with anterior, traditional posterior and paraspinal approach reduction with or without decompression. The fracture was fixed with titanium mesh and Z-plate by anterior approach and screw rod system by posterior approach and paraspinal approach. Clinical evaluations showed operation duration, blood loss, average length of incision and postoperative ODI in the paraspinal group were less than the traditional posterior group and anterior group. The statistical significant differences were reached (P < 0.05). There is not statistical difference between the three approaches for relevant parameters of radiographs (Cobb angle). The anterior approach surgery should be limitedly used for severe Denis type B fracture with direct reduction. The posterior approach is familiar to the spine surgeons and is commonly applied to most Denis type A and B thoracic lumbar fractures with indirect reduction and has less complication compared to the anterior approach, but also has some shortcomings. Paraspinal muscle approach is the muscle gap approach, in line with the minimally invasive surgery , which is now advocated with the idea with indirect reduction, compared to traditional surgery can significantly relieve postoperative pain and is worthy of further research and promotion.

Association between severity of the cervical foraminal stenosis and paraspinal muscle parameters in patients undergoing anterior cervical discectomy and fusion.

OBJECTIVE: The cervical multifidus and rotatores muscles are innervated by the posterior rami of the spinal nerves of the corresponding level, and it has been hypothesized that cervical foraminal stenosis (CFS) affecting the spinal nerves results in changes in these muscles. The purpose of this study was to evaluate the relationship between the severity of CFS and fat infiltration (FI) of the multifidus and rotatores muscles. METHODS: Patients who received preoperative cervical MRI, underwent anterior cervical decompression and fusion between 2015 and 2018, and met inclusion and exclusion criteria were included. Multifidus and rotatores muscles were segmented bilaterally from C3 to C7, and the percent FI was measured using custom-written MATLAB software. The severity of the CFS was assessed by the Kim classification. Multivariable linear mixed models were conducted and adjusted for age, sex, BMI, and repeated measures. RESULTS: In total, 149 patients were included. Linear mixed modeling results showed that a more severe CFS at C3-4 was correlated with a greater FI of the multifidus and rotatores muscles at C4 (estimate 0.034, 95% CI 0.003-0.064; p = 0.031), a more severe CFS at C4-5 was correlated with a greater FI of the multifidus and rotatores muscles at C5 (estimate 0.037, 95% CI 0.015-0.057; p < 0.001), a more severe CFS at C5-6 was correlated with a greater FI of the multifidus and rotatores muscles at C6 (estimate 0.041, 95% CI 0.019-0.062; p < 0.001) and C7 (estimate 0.035, 95% CI 0.012-0.058; p = 0.003), and a more severe CFS at C6-7 was correlated with a greater FI of the multifidus and rotatores muscles at C7 (estimate 0.049, 95% CI 0.027-0.071; p < 0.001). CONCLUSIONS: These results demonstrated level- and side-specific correlations between the FI of the multifidus and rotatores muscles and severity of CFS. Given the segmental innervation of the multifidus and rotatores muscles, the authors hypothesize that the observed increased FI could be reflective of changes due to muscle denervation from CFS.

Irreversible electroporation: treatment effect is susceptible to local environment and tissue properties.

PURPOSE: To study the effects of the surrounding electrical microenvironment and local tissue parameters on the electrical parameters and outcome of irreversible electroporation (IRE) ablation in porcine muscle, kidney, and liver tissue. MATERIALS AND METHODS: Animal Care and Use Committee approval was obtained, and National Institutes of Health guidelines were followed. IRE ablation (n = 90) was applied in muscle (n = 44), kidney (n = 28), and liver (n = 18) tissue in 18 pigs. Two electrodes with tip exposure of 1.5-2 cm were used at varying voltages (1500-3000 V), pulse repetitions (n = 70-100), pulse length (70-100 µsec), and electrode spacing (1.5-2 cm). In muscle tissue, electrodes were placed exactly parallel, in plane, or perpendicular to paraspinal muscle fibers; in kidney tissue, in the cortex or adjacent to the renal medulla; and in liver tissue, with and without metallic or plastic plates placed 1-2 cm from electrodes. Ablation zones were determined at gross pathologic (90-120 minutes after IRE) and immunohistopathologic examination (6 hours after) for apoptosis and heat-shock protein markers. Multivariate analysis of variance with multiple comparisons and/or paired t tests and regression analysis were used for analysis. RESULTS: Mean (± standard deviation) ablation zones in muscle were 6.2 cm ± 0.3 × 4.2 cm ± 0.3 for parallel electrodes and 4.2 cm ± 0.8 × 3.0 cm ± 0.5 for in-plane application. Perpendicular orientation resulted in a cross-shaped zone. Orientation significantly affected IRE current applied (28.5-31.7A for parallel, 29.5-39.7A for perpendicular; P = .003). For kidney cortex, ovoid zones of 1.5 cm ± 0.1 × 0.5 cm ± 0.0 to 2.5 cm ± 0.1 × 1.3 cm ± 0.1 were seen. Placement of electrodes less than 5 mm from the medullary pyramids resulted in treatment effect arcing into the collecting system. For liver tissue, symmetric 2.7 cm ± 0.2 × 1.4 cm ± 0.3 coagulation areas were seen without the metallic plate but asymmetric coagulation was seen with the metallic plate. CONCLUSION: IRE treatment zones are sensitive to varying electrical conductivity in tissues. Electrode location, orientation, and heterogeneities in local environment must be considered in planning ablation treatment. Online supplemental material is available for this article.

Lumbar plexopathy following instrumented posterior lumbar interbody fusion: a complication with use of Hohmann's retractor.

INTRODUCTION: A series of 12 patients in our centre following single level instrumented posterior lumbar interbody fusion at L4-L5 developed unexplainable motor weakness in the proximal lumbar nerve roots (L2, L3) and numbness of the whole limb, a clinical picture resembling lumbar plexopathy. Even though lumbar plexopathy has been reported following gynaecological procedures and in transpsoas interbody fusion surgeries, there is no literature reporting this complication following conventional instrumented posterior lumbar interbody fusions. STUDY DESIGN: Retrospective observational study. OBJECTIVE: To find the possible mechanism of development of lumbar plexopathy in patients who underwent posterior lumbar interbody fusion surgeries in our centre. MATERIAL AND METHODS: We analyzed retrospectively the medical records, electrophysiological reports of the patients, literatures on the anatomy of lumbar plexus and other literature reporting similar complications. We also dissected lumbar plexus of three cadavers and simulated surgical technique on them to find the mechanism of development of this unusual complication. RESULTS: We found injury to lumbar plexus that probably occurred intraoperatively with Hohmann's retractor that was used for retraction of the paraspinal muscles. This theory was favoured by many clinical factors and further confirmed by cadaveric dissections. CONCLUSION: We conclude that surgical technique with improper use of Hohmann's retractor causes traction and compression injury to the lumbar plexus resulting in this complication. We propose proper technique of insertion of Hohmann's retractor and also recommend use of modified Hohmann's retractor with shorter tips for spinal procedures to prevent such complication.

Tubular surgery with the assistance of endoscopic surgery via midline approach for lumbar spinal canal stenosis: a technical note.

PURPOSE: We devised a tubular surgery with the assistance of endoscopic surgery via midline approach to the spinal canal to preserve the bilateral facet joints and the paravertebral muscles when treating lumbar spinal canal stenosis. We report details of this operative procedure. METHODS: A 2-cm incision is made in the skin in the midline of the intervertebral level to be decompressed. The spinous process on the cranial side is partially excised, and incisions along the ligament fiber are made in the midline of the supraspinous and interspinous ligaments to expose the ligamentum flavum. After the lamina and the inferior parts of the bilateral facet joints are adequately excised, the microendoscopic discectomy system is inserted. With this procedure, no muscular tissue is seen in the surgical site. The portal approach is small, but if full advantage is taken of the spinal microendoscope's merits, the bilateral facet joints are preserved and wide decompression of deep parts is possible. The microendoscope is positioned above the spinal canal to provide a good symmetrical field of view to enable easy anatomical orientation. RESULTS: Bilateral intervertebral joints were satisfactorily preserved in ten patients who received this surgery. All became ambulatory on the day after surgery and the clinical results remained favorable 3 years after the operation. CONCLUSION: Tubular surgery with the assistance of endoscopic surgery via a midline approach is a minimally invasive surgical procedure with favorable results that enables preservation of paravertebral muscles and bilateral facet joints.