Posterior Decompression Surgery Research Articles

Discharge Disposition and Clinical Outcomes After Spine Surgery.

Spinal decompression with or without fusion is one of the most commonly performed procedures in spine surgery. However, there is limited evidence on the effect of discharge environment on outcomes after surgery. The purpose of this study is to identify the effects of discharge disposition setting on clinical outcomes after spine surgery. Patients who underwent lumbar decompression, lumbar decompression and fusion, or posterior cervical decompression and fusion surgery were retrospectively identified. All clinical and demographic data were obtained from electronic health records. Surgical outcomes included wound complications, revision surgery, "30-day" readmission (0-30 d), and "90-day" readmission (31-90 d). Discharge disposition was stratified into home/self-care, acute inpatient rehabilitation, and subacute rehabilitation. Patient-reported outcome measures including VAS Back, VAS Leg, VAS Neck, VAS Arm, PCS-12 and MCS-12, ODI, and NDI were compared between patient discharge disposition settings using the Mann-Whitney U test. Pearson's chi-square analysis was used to assess for differences in wound complications, revision surgery, 30-day readmission, or 90-day readmission rates. Multivariate logistic regression incorporating age, sex, body mass index (BMI), Charlson Comorbidity Index (CCI), and discharge disposition was used to determine independent predictors of wound complications. A total of 637 patients were included in the study. A significant difference (P = 0.03) was found in wound complication based on discharge disposition, with subacute disposition having the highest proportion of wound complications (6.1%) and home disposition having the lowest (1.5%). There were no significant differences in the rates of revision surgery, 30-day readmission, or 90-day readmission between groups. Subacute rehabilitation (odds ratio: 3.67, P = 0.047) and CCI (odds ratio 1.49, P = 0.01) were independent predictors of wound complications. Significant improvement in PROMs was seen across all postacute discharge dispositions. Baseline (P = 0.02) and postoperative (P = 0.02) ODI were significantly higher among patients discharged to an acute facility (49.4 and 32.0, respectively) compared to home (42.2 and 20.0) or subacute (47.4 and 28.4) environments. Subacute rehabilitation disposition and CCI are independent predictors of wound complications after spinal decompression surgery. Patients undergoing spine surgery have similar readmission and revision rates and experience similar clinical improvement across all postacute discharge dispositions.

White Cord Syndrome: A Reperfusion Injury Following Spinal Decompression Surgery

Reperfusion injury of the spinal cord has been scarcely reported. Herein, we present a case of white cord syndrome after spinal decompression. A 61-year-old male, who initially had ossification of the posterior longitudinal ligament at C3-6 level, was admitted to our hospital with a ruptured disc at the C6-7 level. The patient experienced radiating pain in both upper extremities. Anterior cervical discectomy and fusion was performed. However, the patient developed quadriplegia. Emergency magnetic resonance imaging revealed a new and enlarged signal change in the spinal cord at the C4-7 level. Additional posterior decompression surgery was performed. After intense rehabilitation, the patient's motor function improved to grade 4. White cord syndrome is likely due to reperfusion injury following operative decompression of a compressed spinal cord segment. Although rare, spine surgeons should be aware of this complication and warn patients preoperatively.

Improvement in Neurogenic Bowel and Bladder Dysfunction Following Posterior Decompression Surgery for Cauda Equina Syndrome: A Prospective Cohort Study.

ObjectiveThe mechanisms of neurogenic bowel dysfunction (NBD) and neurogenic bladder (NB), which are major consequences of spinal cord injury and occasionally degenerative lumbar disease. The following in patients with cauda equina syndrome who underwent posterior decompression surgery was investigated: (1) the preoperative prevalence of NBD and NB, measured using the Constipation Scoring System (CSS) and International Prostate Symptoms Score (IPSS); (2) the degree and timing of postoperative improvement of NBD and NB. MethodsWe administered the CSS and IPSS in 93 patients before surgery and at 1, 3, 6, and 12 months postoperatively. We prospectively examined patient characteristics, Japanese Orthopaedic Association (JOA) score, and postoperative improvements in each score. ResultsThe prevalence of symptomatic defecation and urinary symptoms at admission were 37 patients (38.1%) and 31 patients (33.3%), respectively. Among the symptomatic patients with defecation problems, 12 patients had improved at 1 month, 13 at 3 months, 14 at 6 months, and 13 at 12 months postoperatively. Among the symptomatic patients with urinary problems, 5 patients improved at 1 month, 11 at 3 months, 6 at 6 months, and 10 at 1 year postoperatively. Comparing patients with improved versus unimproved in CSS, the degree of JOA score improvement was a significant prognosis factor (p<0.05; odds ratio, 1.05). ConclusionThe prevalence of symptomatic defecation and urinary symptoms in patients with cauda equina syndrome was 38.1% and 33.3%, respectively. Decompression surgery improved symptoms in 30%–50%. These effects were first observed 1 month after the operation and persisted up to 1 year.

Synovial facet joint cysts after lumbar posterior decompression surgery.

Numerous studies have reported on synovial facet joint cysts of the spine as a primary lesion. The exact pathogenesis of those cysts is still controversial, but degeneration and destabilization seem to be underlying mechanisms. However, only a few reports have thus far investigated synovial cysts of the spine as postoperative complications of decompression surgery. In this retrospective clinical study, the authors focused on synovial cysts of the lumbar facet joints as complications after lumbar decompression surgery, with the aim of elucidating their pathophysiology. A total of 326 patients with 384 segments treated with posterior decompression surgery without fusion were included in the study. Of these segments, 107 were surgically decompressed unilaterally and 277 were decompressed bilaterally. After surgery, 18 of the 384 segments developed a complication of symptomatic facet synovial cyst. The anatomical and morphological evaluations of these segments were performed using functional plain radiographs, CT scans, and MR images. All of the 18 segments with postoperative lumbar facet synovial cyst were treated with bilateral lumbar posterior decompression. There was no significant radiological lumbar spinal instability in any segments, although 17 of 18 segments demonstrated facet articular spondylotic changes. Moreover, 12 of 18 patients demonstrated lumbar retrolisthesis in the neutral position. Based on the authors' results, they propose that patients with lumbar degenerative disease who have a potential biomechanical lumbar instability such as disruption of the facet articular surface and hydrarthrosis or lumbar facet tropism might have a high risk for formation of lumbar facet synovial cyst after bilateral posterior decompression surgery.

Comparison between microendoscopic laminectomy and open posterior decompression surgery for single-level lumbar spinal stenosis: a multicenter retrospective cohort study

BackgroundMicroendoscopic laminectomy (MEL), in which a 16-mm tubular retractor with an internal scope is used, has shown excellent surgical results for patients with lumbar spinal canal stenosis. However, no reports have directly compared MEL with open laminectomy. This study aimed to elucidate patient-reported outcomes (PROs) and perioperative complications in patients undergoing MEL versus open laminectomy.MethodsThis is a multicenter retrospective cohort study of prospectively registered patients who underwent lumbar spinal surgery at one of the six high-volume spine centers between April 2017 and September 2018. A total of 258 patients who underwent single posterior lumbar decompression at L4/L5 were enrolled in the study. With regard to demographic data, we prospectively used chart sheets to evaluate the diagnosis, operative procedure, operation time, estimated blood loss, and complications. The follow-up period was 1-year. PROs included a numerical rating scale (NRS) for lower back pain and leg pain, the Oswestry Disability Index (ODI), EuroQol 5 Dimension (EQ-5D), and patient satisfaction with the treatment.ResultsOf the 258 patients enrolled, 252 (97%) completed the 1-year follow-up. Of the 252, 130 underwent MEL (MEL group) and 122 underwent open decompression (open group). The MEL group required a significantly shorter operating time and sustained lesser intraoperative blood loss compared with the open group. The MEL group showed shorter length of postoperative hospitalization than the open group. The overall complication rate was similar (8.2% in the MEL group versus 7.7% in the open group), and the revision rate did not significantly differ. As for PROs, both preoperative and postoperative values did not significantly differ between the two groups. However, the satisfaction rate was higher in the MEL group (74%) than in the open group (53%) (p = 0.02).ConclusionsMEL required a significantly shorter operating time and resulted in lesser intraoperative blood loss compared with laminectomy. Postoperative PROs and complication rates were not significantly different between the procedures, although MEL demonstrated a better satisfaction rate.

Motor Bur Milling State Identification via Fast Fourier Transform Analyzing Sound Signal in Cervical Spine Posterior Decompression Surgery.

ObjectivesTo investigate the real‐time sensitive feedback parameter of the motor bur milling state in cervical spine posterior decompression surgery, to possibly improve the safety of cervical spine posterior decompression and robot‐assisted spinal surgeries.MethodsIn this study, the cervical spine of three healthy male and three healthy female pigs were randomly selected. Six porcine cervical spine specimens were fixed to the vibration isolation system. The milling state of the motor bur was defined as the lamina cancellous bone (CA), lamina ventral corticalbone (VCO), and penetrating ventral cortical bone (PVCO). A 5‐mm bur milled the CA and VCO, and a 2‐mm bur milled the VCO and PVCO. A miniature microphone was used to collect the sound signal (SS) of milling lamina which was then extracted using Fast Fourier Transform (FFT). When using 5‐mm and 2‐mm bur to mill, the CA, VCO, and PVCO of each specimen were continuously collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 kHz frequencies for SS magnitudes. The study randomly selected the SS magnitudes of the CA and VCO continuously for 2 s at 1, 2, 3, 4, and 5 kHz frequencies for statistical analyses. When milling the VCO to the PVCO, we randomly collected the SS magnitudes of the VCO for consecutive 2 s and the SS magnitudes of continuous 2 s in the penetrating state at 1, 2, 3, 4, and 5 kHz frequencies for statistical analyses. The independent sample t‐test was used to compare the SS magnitudes of different milling states extracted from the FFT to determine the motor bur milling state.ResultsThe SS magnitudes of the CA and VCO of all specimens extracted from the FFT at 1, 2, and 3 kHz were statistically different (P < 0.01); three specimens were not statistically different at a specific FFT‐extracted frequency (first specimen at 5 kHz, SS magnitudes of the CA were [25.94 ± 8.74] × 10−3, SS magnitudes of the VCO were [28.67 ± 12.94] × 10−3, P = 0.440; second specimen at 4 kHz, SS magnitudes of the CA were [23.79 ± 7.94] × 10−3, SS magnitudes of the VCO were [24.78 ± 4.32] × 10−3, P = 0.629; and third specimen at 5 kHz, SS magnitudes of the CA were [16.76 ± 6.20] × 10−3, SS magnitudes of the VCO were [17.69 ± 6.44] × 10−3, P = 0.643).The SS magnitudes of the VCO and PVCO of all the specimens extracted from the FFT at each frequency were statistically different (P < 0.001).ConclusionsBased on the FFT extraction, the SS magnitudes of the motor bur milling state between the CA and VCO, the VCO and PVCO were significantly different, confirming that the SS is a potential sensitive feedback parameter for identifying the motor bur milling state. This study could improve the safety of cervical spine posterior decompression surgery, especially of robot‐assisted surgeries.

Temporal Evolution of White Blood Cell Count and Differential: Reliable and Early Detection Markers for Surgical Site Infection Following Spinal Posterior Decompression Surgery.

Introduction For early detection of surgical site infection (SSI) following spinal decompression surgery, we compared temporal changes in the values of laboratory markers that are not affected by operative parameters. Methods The study included 302 patients, which were divided into an SSI group (patients who developed deep SSI) and a non-SSI group for analysis. We reviewed data on C-reactive protein level, total white blood cell (WBC) count, and WBC differential percentage and count before spinal decompression, on postoperative day 1, and on postoperative day 4. We identified laboratory markers that are not affected by operative parameters (operating time, intraoperative blood loss, and number of operative segments). Laboratory markers with a significant difference observed between the peak or nadir value and the value in the subsequent survey day were considered as an indicator of SSI. We examined the utility of each indicator by calculating sensitivity and specificity. Furthermore, we investigated the utility of the combination of all five indicators (wherein the recognition of one marker was considered positive). Results Temporal changes in five laboratory markers were considered indicators of SSI. The changes from postoperative day 1 to postoperative day 4 were as follows: (1) increased WBC count (42% sensitivity, 88% specificity), (2) increased neutrophil percentage (25% sensitivity, 96% specificity), (3) increased neutrophil count (25% sensitivity, 94% specificity), (4) decreased lymphocyte percentage (25% sensitivity, 95% specificity), and (5) decreased lymphocyte count (25% sensitivity, 85% specificity). The combination of these five markers showed a 50% sensitivity, 81% specificity, and 0.65 AUC. Conclusions Five markers were found to be reliable indicators of SSI following spinal decompression surgery because they were not affected by operative parameters. The combination of all five indicators had moderate sensitivity and high specificity. Therefore, this may be reliable and useful for the early detection of SSI.

Influence of Intervertebral Level of Stenosis on Neurological Recovery and Reduction of Neck Pain After Posterior Decompression Surgery for Cervical Spondylotic Myelopathy: A Retrospective Multicenter Study with Propensity Scoring.

Retrospective multicenter study. To identify the impact of the intervertebral level of stenosis on surgical outcomes of posterior decompression for cervical spondylotic myelopathy (CSM). As the upper affected cervical levels in elderly patients result from degenerative changes in the lower cervical levels with aging, it is usually difficult to determine the influence of the upper affected cervical levels on surgical outcomes after posterior decompression for CSM in older age. This study involved 636 patients with CSM who underwent posterior decompression. According to the most stenotic intervertebral level, patients were divided into upper (n = 343, the most stenotic intervertebral level was C2/3, C3/4, or C4/5) and lower (n = 293, the most stenotic intervertebral level was C5/6, C6/7, or C7/T1) cervical stenosis groups. Propensity score matching of the baseline factors (characteristics, comorbidities, and neurological function) was performed to compare surgical outcomes, the Japanese Orthopaedic Association (JOA) scores, and visual analog scale (VAS) for neck pain between the upper (n = 135) and lower (n = 135) cervical stenosis groups. Before propensity score matching, age at surgery was older and pre- and postoperative JOA scores were lower in the upper cervical stenosis group (P < 0.001, P < 0.001, and P < 0.001, respectively). Following matching, baseline factors were comparable between the groups. Postoperative JOA scores, preoperative-to-postoperative changes in the JOA scores, and the JOA score recovery rate were not significantly different between the groups (P = 0.866, P = 0.825, and P = 0.753, respectively). No differences existed in postoperative VAS for neck pain and preoperative-to-postoperative changes in VAS for neck pain between the groups (P = 0.092 and P = 0.242, respectively). The intervertebral level of stenosis did not affect surgical outcomes after posterior decompression for CSM.Level of Evidence: 3.

Transcranial Motor-evoked Potential Alert After Supine-to-Prone Position Change During Thoracic Ossification in Posterior Longitudinal Ligament Surgery: A Prospective Multicenter Study of the Monitoring Committee of the Japanese Society for Spine Surgery and Related Research.

A prospective, multicenter study. To evaluate the usefulness of transcranial motor-evoked potentials (Tc-MEPs) during supine-to-prone position change for thoracic ossification of the posterior longitudinal ligament (T-OPLL). Supine-to-prone position change might be a risk of spinal cord injury in posterior decompression and fusion surgeries for T-OPLL. The subjects were 145 patients with T-OPLL surgically treated with posterior decompression and fusion using Tc-MEPs in 14 institutes. Tc-MEPs were monitored before surgery from supine-to-prone position and intraoperatively in seven institutes and only intraoperatively in the other seven institutes because of disapproval of the anesthesia department. In cases of Tc-MEP alert after position change, we adjusted the cervicothoracic posture. When the MEP did not recover, we reverted the position to supine and monitored the Tc-MEPs in supine position. There were 83 and 62 patients with/without Tc-MEP before position change to prone (group A and B). The true-positive rate was lower in group A than group B, but without statistical significance (8.4% vs. 16.1%, P = 0.12). In group A, five patients who had Tc-MEP alert during supine-to-prone position change were all female and had larger body mass index values and upper thoracic lesions. Among the patients, three underwent surgeries after cervicothoracic alignment adjustment, and two had postponed operations to 1 week later with halo-vest fixation because of repeated Tc-MEP alerts during position change to prone. The Tc-MEP alert at exposure was statistically more frequent in group B than in group A ( P = 0.033). Tc-MEP alert during position change is an important sign of spinal cord injury due to alignment change at the upper thoracic spine. Tc-MEP monitoring before supine-to-prone position change was necessary to prevent spinal cord injury in surgeries for T-OPLL.

Nerve root morphological and functional changes after degenerative cervical myelopathy surgery: preliminary study using ultrasound and electrophysiology

A prospective observational study. To depict morphological and functional changes in the cervical nerve roots before and after spinal cord decompression surgery for degenerative cervical myelopathy (DCM). A general hospital in Japan. Thirteen DCM patients who underwent posterior spinal cord decompression surgery, laminoplasty or laminectomy, were included in this study. The neural foramen shown on MRI and the cross-sectional area (CSA) of the nerve roots on ultrasound were used to evaluate the C5 and C6 nerve roots. The compound muscle action potentials (CMAPs) of deltoid and biceps muscle were also recorded. All patients showed sensorimotor functional improvement without the postoperative C5 palsy after surgery. Foraminal stenosis and preoperative CSA of the nerve root: C4/5 foramen and C5 nerve root, C5/6 foramen and C6 nerve root, had no significant correlation (P = 0.53 and 0.08). CSA of the C5 nerve root displayed no significant change before and after surgery (P = 0.2), however, that of the C6 nerve root reduced significantly after surgery (P = 0.038). The amplitude of the deltoid and biceps CMAPs displayed no significant change before and after surgery (P = 0.05 and 0.05). The C6 nerve root CSA change was observed after spinal cord decompression surgery with functional recovery. However, deltoid and biceps CMAPs amplitude showed no significant change. Independent CSA changes on ultrasound might be useful when conducting a functional evaluation of the postoperative nerve root. The Grant of Japan Orthopaedics and Traumatology Research Foundation No. 395.

Alleviating Paravertebral Muscle Spasm after Radiofrequency Ablation Treatment of Hypersensitive Basivertebral and Sinuvertebral Nerves for Chronic Discogenic Back Pain

Paraspinal muscle spasm caused by pain from a lumbar degenerative disc is frequently investigated in patients with low back pain. Radiofrequency ablation (RFA) surgery could alleviate paraspinal muscle spasms. We performed RFA surgery on the high-intensity zone (HIZ) and hypersensitive sinuvertebral and basivertebral nerves to evaluate its outcome. The paravertebral muscle cross-sectional area (CSA) was measured on magnetic resonance imaging (MRI) before and after surgery to evaluate the effect of RFA surgery on the paravertebral muscle. Prospective cohort study. A single spine surgery center. A comparative study was performed on 2 different uniportal spinal endoscopic surgery groups; 23 patients who underwent RFA surgery for chronic discogenic back pain and 45 patients who underwent posterior decompression surgery for lumbar spinal stenosis with 12 months of follow-up. Paravertebral muscle cross-sectional area, Schiza grade, Modic type, and HIZ size were measured on pre- and post-operative MRI. An endoscopic video review was performed to evaluate the presence of intraoperative twitching and grade the degree of epidural neovascularization and adhesion. Visual analog scale VAS, modified Oswestry Disability Index, ODI and MacNab's criteria were evaluated for outcome measures. Intraoperative endoscopic video evaluation showed neovascularization and adhesion adjacent to the disc and pedicle. In the RFA surgery group, there were 7 patients (30.43%) with grade 2 and 16 (69.57%) with grade 3 neovascularization; intraoperative twitching was observed in 19 out of 23 patients (82.61%). After performing an RFA on the sinuvertebral and basivertebral nerves for the treatment of discogenic back pain, the results showed significant improvement in pain and disability scores. The mean CSA of the paraspinal muscle in the RFA surgery group was significantly increased after surgery at the L4-L5 and L5-S1 levels (L4-L5: 3901 ± 1096.7 mm² to 4167 ± 1052.1 mm², P = 0.000; L5-S1: 3059 ± 968.5 mm² to 3323 ± 1046.2 mm², P = 0.000) compared to preoperative CSA. This study was limited by its small sample size. Hypersensitive sinuvertebral and basivertebral nerves are strongly associated with epidural neovascularization with adhesion and the pathological pain pathway in degenerative disc disease. Epidural neovascularization with adhesion reflects aberrant neurological connections, which are associated with reflex inhibitory mechanisms of the multifidus muscle, which induces spasm. RFA treatment of the region of epidural neovascularization with adhesion effectively treated chronic discogenic back pain and could induce paraspinal muscle spasm release.

Combined Motor and Sensory Intraoperative Neuromonitoring for Cervical Spondylotic Myelopathy Surgery Causes Confusion: A Level-1 Diagnostic Study.

Level-1 diagnostic study. The purpose of this study was to evaluate the sensitivity and specificity of combined motor and sensory intraoperative neuromonitoring (IONM) for cervical spondylotic myelopathy (CSM). Intraoperative neuromonitoring during spine surgery began with sensory modalities with the goal of reducing neurological complications. Motor monitoring was later added and purported to further increase sensitivity and specificity when used in concert with sensory monitoring. Debate continues, however, as to whether neuromonitoring reliably detects reversible neurologic changes during surgery or simply adds set-up time, cost, or mere medicolegal reassurance. Neuromonitoring data using combined motor and sensory evoked potentials for 540 patients with CSM undergoing anterior or posterior decompressive surgery were collected prospectively. Patients were examined postoperatively to determine the clinical occurrence of new neurologic deficit which correlated with monitoring alerts recorded per established standard criteria. The overall incidence of positive IONM alerts was 1.3% (N = 7) all of which were motor alerts. All were false positives as no patient had clinical neurological deterioration post-operatively. The false-positive rate was 1.4% (N = 146) for anterior surgeries and 1.3% (N = 394) for posteriors with no statistical difference between them (P = 1.0, Fisher exact test). There were no false-negative alerts, and all negatives were true negatives (N = 533). The overall sensitivity of detecting a new neurologic deficit was 0%, overall specificity 98.7%. Combined motor and sensory neuromonitoring for CSM patients created a confusing choice between the motor or sensory data when in disagreement in 1.3% of surgical patients. Criterion standard clinical examinations confirmed all motor alerts were false positives. Surgical plan was negatively altered by following false motor alerts early on, but disregarded in later cases in favor of sensory data. Neuromonitoring added set-up time and cost, but without clear benefit in this series.Level of Evidence: 4.

An Experimental Rat Model of C5 Palsy Following Posterior Decompression Surgery of the Cervical Spine.

Basic in vivo research. The aim of this study was to establish an animal model that is appropriate for analyzing the mechanisms of C5 palsy (C5P) and to clarify the structural and functional alterations of cervical roots following posterior decompression. Although C5P is one of the major complications of cervical surgery, the exact pathogenesis of C5P remains unclear partly because of the lack of an appropriate animal model. Tethering of the cervical roots due to posterior cord shift following posterior decompression is thought to be one of the possible factors that cause C5P. Twenty-eight Sprague-Dawley rats were divided into Group L (cervical laminectomy, N = 18) or Group S (sham surgery, N = 10) and examined up to postoperative day 14 (PO14). Posterior cord shift and the length of the anterior rootlets were quantified by computed tomography-myelogram images. Motor evoked potential (MEP) of the deltoid (C5, 6 innervated) and triceps brachii (C7-T1 innervated), mechanical allodynia, and grip strength of the forepaw (C7-T1 regulated) were measured. All anterior rootlets were elongated as the cord gradually shifted posteriorly postoperatively. The elongation rate of the C6 anterior rootlets was the highest (142% at PO14). The MEP latency of the deltoid was significantly delayed throughout all postoperative time points. However, significant delay in the latency of the triceps brachii was observed only on postoperative day 10. The withdrawal threshold of the forepaw did not change; grip strength of the forelimb decreased at PO14. This model was thought to be appropriate for analyzing the pathogenesis of C5P since our findings were comparable to the clinical course of C5P subsequent to posterior cervical decompression. Although a future study for clarifying histological and molecular alterations will be needed, tethering of the anterior rootlets due to posterior cord shift was suggested to be a probable mechanism causing C5P.Level of Evidence: 5.

Risk Factors for Cervical Deformity After Posterior Cervical Decompression Surgery: A Multicenter Study.

Retrospective multicenter study. Posterior decompression surgery for cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL) is a common surgery; however, it can cause postoperative cervical deformity (CD). The purpose of this study was to investigate the risk factors for CD. The participants were 193 patients underwent laminoplasty or laminectomy for CSM or OPLL. CD was defined as a C2-7 sagittal vertical axis (SVA) ≥ 40 mm or a cervical lordosis angle (CL) ≤ -10°. The participants were divided into 2 groups: NCD (without CD before surgery), CD (with CD before surgery). NCD group was divided based on the presence of CD 1 year after surgery as follows: postoperative CD (PCD) and no PCD (NPCD). There were 153 patients (NCD), 40 (CD), 126 (NPCD), and 27 (PCD). There was significant difference in the number of decompressed lamina (NPCD: PCD = 4.1:4.5), the presence of C2 decompression (2: 11%), and C5 palsy (0: 11%). The risk factors for onset of CD, PCD, and CL ≤ -10° as assessed by multiple logistic regression analysis were preoperative C2-7 SVA ≥ 30 mm (odds ratio [OR]: 19.0), decompression of C2 or C7 lamina (OR 3.1), and preoperative CL ≤ 2° (OR 42.0), respectively. To prevent postoperative CD, it is important to avoid decompression of the C2 or C7 lamina. Moreover, in case with C2-7 SVA ≥ 30 mm or CL ≤ 2° before surgery, it is important to explain the risks and consider adding fusion surgery.

Postoperative lumbar spine MRI: How well does a radiology report that raises suspicion for infection correlate with true clinical infection?

IntroductionInterpretation of a lumbar spine MRI in the immediate postoperative period is challenging, as postoperative tissue enhancement and fluid collections may be mistaken for infection. Radiology reports may use ambiguous language, creating a clinical problem for a surgeon in determining whether a patient needs treatment with antibiotics or revision surgery. Moreover, retrospective criticism of management in instances of a true infection may lead to medicolegal ramifications. MethodsA retrospective review of patients undergoing posterior-approach lumbar decompressive surgery with or without fusion over a 30-month period identified those undergoing postoperative MRI within 10 weeks of surgery. Patients initially operated upon for infection were excluded. The MRI reports were analyzed for language describing findings suspicious for infection and those of these with true infections were identified. ResultsOf 487 patients undergoing posterior lumbar spine decompression surgery, 68 (14%) had postoperative MRI within 10 weeks. Of these, the radiology reports raised suspicion for infection in 20 (29%), of which 2 (10%) patients had a true infection. Two patients underwent reoperation for new motor deficit from seroma/hematoma. Of 63 patients who had MRI to evaluate complaints of back and/or leg pain without new motor deficits, the MRI significantly altered management in 3 patients (4.8%). ConclusionRadiology reports of postoperative lumbar spine MRIs frequently use language that raises suspicion for infection; but it is uncommon, however, that these patients harbor true infections. A radiology report describing possible infectious findings may not be considered significant without corroboration with other laboratory and clinical data.

Cerebellar and Brainstem Displacement Measured with DENSE MRI in Chiari Malformation Following Posterior Fossa Decompression Surgery

Background Posterior fossa decompression (PFD) surgery is a treatment for Chiari malformation type I (CMI). The goals of surgery are to reduce cerebellar tonsillar crowding and restore posterior cerebral spinal fluid flow, but regional tissue biomechanics may also change. MRI-based displacement encoding with stimulated echoes (DENSE) can be used to assess neural tissue displacement. Purpose To assess neural tissue displacement by using DENSE MRI in participants with CMI before and after PFD surgery and examine associations between tissue displacement and symptoms. Materials and Methods In a prospective, HIPAA-compliant study of patients with CMI, midsagittal DENSE MRI was performed before and after PFD surgery between January 2017 and June 2020. Peak tissue displacement over the cardiac cycle was quantified in the cerebellum and brainstem, averaged over each structure, and compared before and after surgery. Paired t tests and nonparametric Wilcoxon signed-rank tests were used to identify surgical changes in displacement, and Spearman correlations were determined between tissue displacement and presurgery symptoms. Results Twenty-three participants were included (mean age ± standard deviation, 37 years ± 10; 19 women). Spatially averaged (mean) peak tissue displacement demonstrated reductions of 46% (79/171 µm) within the cerebellum and 22% (46/210 µm) within the brainstem after surgery (P < .001). Maximum peak displacement, calculated within a circular 30-mm2 area, decreased by 64% (274/427 µm) in the cerebellum and 33% (100/300 µm) in the brainstem (P < .001). No significant associations were identified between tissue displacement and CMI symptoms (r < .74 and P > .012 for all; Bonferroni-corrected P = .0002). Conclusion Neural tissue displacement was reduced after posterior fossa decompression surgery, indicating that surgical intervention changes brain tissue biomechanics. For participants with Chiari malformation type I, no relationship was identified between presurgery tissue displacement and presurgical symptoms. © RSNA, 2021 Online supplemental material is available for this article.

Impact of various MRI signal intensity changes on radiological parameters, the neurological status, and surgical outcomes in degenerative cervical myelopathy

Study designA retrospective study of prospectively collected date. PurposeThe present study aimed to identify patient characteristics, radiological factors, the neurological status, and postoperative outcomes associated with MRI signal intensity changes in degenerative cervical myelopathy (DCM). Material and methodOne hundred and fourteen DCM patients who underwent posterior decompression surgeries were enrolled. Pre- and postoperative (12 months) Japanese Orthopedic Association (JOA) scores, cervical alignment and balance on X rays, the cross-sectional area of the spinal cord (CSA) in kinematic CT myelography (CTM). The recovery rate (RR) of the total JOA score and those specific for the upper and lower limb items were evaluated. MRI included T1-weighted imaging (WI) and T2WI. Patients were classified into two groups for a univariate analysis according to the presence or absence of a high signal intensity (HIS) in the sagittal view on T2WI, a low signal intensity (LSI) in the sagittal view on T1WI, the distribution of HSI at a single or multiple levels, and the presence or absence of the snake eye appearance. A multiple logistic regression analysis (MLRA) was performed to identify factors associated with signal intensity changes on MRI. ResultsNinety-six patients (84.3%) were classified into HIS changes in the sagittal view on T2WI. The group with multilevel HSI showed significantly lower RR specific for the lower extremity JOA score (30.8% vs 47.7%; P = 0.016). The snake eye-positive group showed a significantly inferior RR specific for the upper extremity JOA score (40.1% vs 53.2%; P = 0.04).In MLRA, LSI changes on T1WI revealed small CSAF (P = 0.02, Odds ratio; 0.77, 95%CI:0.61–0.97), while HSI changes on T2WI revealed a small CSAF (P = 0.008, Odds ratio;1.36, 95%CI:1.08–1.72) and large C2–7 angle during extension (P = 0.009, Odds ratio;0.73, 95%CI:0.58–0.92). CSAF correlated with multilevel HSI changes (P = 0.006, Odds ratio;0.78, 95%CI:0.66–0.93). The snake eye appearance correlated with CSAF (P = 0.006, Odds ratio;0.78, 95%CI:0.66–0.93) and the duration of disease (P = 0.05, Odds ratio;1.01, 95%CI:1.0–1.03). ConclusionSevere and poorly compensated spinal cord compression during neck flexion may cause signal intensity changes. The snake eye appearance may be useful as a sign of the inferior postoperative recovery of upper limb function, and multilevel HSI as a sign of the inferior postoperative recovery of lower limb function.

Reasons for revision following stand-alone anterior lumbar interbody fusion and lateral lumbar interbody fusion.

Anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) are alternative and less invasive techniques to stabilize the spine and indirectly decompress the neural elements compared with open posterior approaches. While reoperation rates have been described for open posterior lumbar surgery, there are sparse data on reoperation rates following these less invasive procedures without direct posterior decompression. This study aimed to evaluate the overall rate, cause, and timing of reoperation procedures following anterior or lateral lumbar interbody fusions without direct posterior decompression. This was a retrospective cohort study of all consecutive patients indicated for an ALIF or LLIF for lumbar spine at a single academic institution. Patients who underwent concomitant posterior fusion or direct decompression surgeries were excluded. Rates, causes, and timing of reoperations were analyzed. Patients who underwent a revision decompression were matched with patients who did not require a reoperation, and preoperative imaging characteristics were analyzed to assess for risk factors for the reoperation. The study cohort consisted of 529 patients with an average follow-up of 2.37 years; 40.3% (213/529) and 67.3% (356/529) of patients had a minimum of 2 years and 1 year of follow-up, respectively. The total revision rate was 5.7% (30/529), with same-level revision in 3.8% (20/529) and adjacent-level revision in 1.9% (10/529) of patients. Same-level revision patients had significantly shorter time to revision (7.14 months) than adjacent-level revision patients (31.91 months) (p < 0.0001). Fifty percent of same-level revisions were for a posterior decompression. After further analysis of decompression revisions, an increased preoperative canal area was significantly associated with a lower risk of further decompression revision compared to the control group (p = 0.015; OR 0.977, 95% CI 0.959-0.995). There was a low reoperation rate after anterior or lateral lumbar interbody fusions without direct posterior decompression. The majority of same-level reoperations were due to a need for further decompression. Smaller preoperative canal diameters were associated with the need for revision decompression.

Extreme cases in percutaneous transforaminal endoscopic surgery: case series and brief review of the literature

Purpose Percutaneous transforaminal endoscopic decompression (PTED) is a minimally invasive method of surgical treatment of miscellaneous spinal conditions. We describe our experience with PTED in extreme cases of foraminal stenosis (FS) in adult degenerative scoliosis (ADS), recurrent foraminal stenosis (RFS) after previous open decompression surgery and adjacent segment disease (ASD) after previous lumbar fusion. Methods Twenty-one (21) patients with FS encountered in the clinical framework of ADS (n = 6), previous open decompression surgery (n = 8) and ASD (n = 7) were prospectively reviewed. Patients were preoperatively assessed via clinical and radiologic evaluation. All patients underwent PTED in 2018–2019. Postoperative evaluation was conducted with clinical examination and evaluation of Visual Analogue Scale (VAS), Oswestry Disability Index (ODI) and modified MacNab criteria in predetermined chronic intervals in a 1–2 years follow-up. Results All patients were successfully managed with PTED. Operated levels were L3–L4 (19.0%), L4–L5 (52.4%) and L5–S1 (28.6%). No major perioperative complications were recorded. VAS and ODI scores were demonstrated to exhibit a clinically and statistically significant (p < 0.05) amelioration in all patients’ categories directly postoperatively, which was preserved until the end of follow-up. Overall outcomes according to modified MacNab criteria were excellent in 12 patients (57.1%), good in 6 (28.6%) and fair in 3 (14.3%) patients. Conclusions PTED is safe and effective in extreme cases of FS encountered in patients with ADS, previous posterior open decompression surgery and ASD after previous spinal fusion.

Adult Age Differences in Self-Reported Pain and Anterior CSF Space in Chiari Malformation.

Chiari malformation type I (CMI) is a neural disorder with sensory, cognitive, and motor defects, as well as headaches. Radiologically, the cerebellar tonsils extend below the foramen magnum. To date, the relationships among adult age, brain morphometry, surgical status, and symptom severity in CMI are unknown. The objective of this study was to better understand the relationships among these variables using causal modeling techniques. Adult CMI patients (80% female) who either had (n = 150) or had not (n = 151) undergone posterior fossa decompression surgery were assessed using morphometric measures derived from magnetic resonance images (MRI). MRI-based morphometry showed that the area of the CSF pocket anterior to the cervico-medullary junction (anterior CSF space) correlated with age at the time of MRI (r = - .21). Also, self-reported pain increased with age (r = .11) and decreased with anterior CSF space (r = - .18). Age differences in self-reported pain were mediated by anterior CSF space in the cervical spine area-and this effect was particularly salient for non-decompressed CMI patients. As CMI patients age, the anterior CSF space decreases, and this is associated with increased pain-especially for non-decompressed CMI patients. It is recommended that further consideration of age-related decreases in anterior CSF space in CMI patients be given in future research.