Radiographic and Clinical Results of C1 Laminoplasty for the Treatment of Compressive Myelopathy.

STUDY DESIGN: Case series. PURPOSE: To evaluate the radiographic and clinical results of C1 laminoplasty without fusion. OVERVIEW OF LITERATURE: C1 laminectomy has been the standard procedure for decompression at the C1 level. However, there have been some reports of trouble cases after C1 laminectomy. C1 laminoplasty might be superior to C1 laminectomy with regard to maintaining the original C1 anatomical shape, preventing compression from the posterior soft tissue, and ensuring an adequate bonegrafting site around the C1 posterior part if additional salvage fusion surgery is necessary afterward. METHODS: Seven patients with spinal cord compression without obvious segmental instability at the C1/2 level treated by C1 laminoplasty were included. The indication of C1 laminoplasty was same as that of C1 laminectomy. C1 laminoplasty was performed in the same way as subaxial double-door laminoplasty. The imaging findings were evaluated using X-ray, computed tomography, and magnetic resonance imaging. The clinical results were evaluated using the Japanese Orthopaedic Association (JOA) Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) and JOA score. Peri- and postoperative complications were also investigated. RESULTS: No patient showed increased C1/2 segmental instability after the surgery. The mean pre- and postoperative JOA scores were 8.6 and 11.7, respectively. The mean recovery rate was 40.2%. The effective rate in the JOACMEQ was 50% for the cervical spine function, 33% for the upper extremity function, 50% for the lower extremity function, 17% for the bladder function, and 17% for the quality of life. No major complication that seemed to be unique to C1 laminoplasty was observed over a period of about 4 years follow-up. CONCLUSIONS: C1 laminoplasty for patients without obvious segmental instability might be a viable alternative procedure to C1 laminectomy.

The effectiveness of a percutaneous endoscopic approach in a patient with psoas and epidural abscess accompanied by pyogenic spondylitis: a case report.

BACKGROUND: Psoas or epidural abscesses are often accompanied by pyogenic spondylitis and require drainage. Posterolateral percutaneous endoscopic techniques are usually used for hernia discectomy, but this approach is also useful in some cases of psoas or lumbar ventral epidural abscess. We here report a case of psoas and epidural abscesses accompanied by pyogenic spondylitis that was successfully treated by percutaneous endoscopic drainage. CASE PRESENTATION: Our patient was a 57-year-old Japanese woman who had been receiving chemotherapy for inflammatory breast cancer and who became unable to walk due to lower back and left leg pain. She was transported as an emergency to another hospital. Magnetic resonance imaging revealed psoas and epidural abscesses accompanied by pyogenic spondylitis, and methicillin-resistant Staphylococcus aureus was detected in a blood culture. Drainage of the psoas abscess was performed under echo guidance, but was not effective, and she was transferred to our institution. We performed percutaneous endoscopic drainage for the psoas and epidural abscesses. Immediate pain relief was achieved and the inflammatory reaction subsided after 8 weeks of antibiotic therapy with daptomycin. CONCLUSIONS: Percutaneous endoscopy allowed us to approach the psoas and epidural abscesses directly, enabling the immediate drainage of the abscesses with less burden on the patient.

Kyphosis Progression after Balloon Kyphoplasty Compared with Conservative Treatment.

STUDY DESIGN: Retrospective cohort study (level of evidence: 4). PURPOSE: To demonstrate the effects of balloon kyphoplasty (BKP) on prevention of kyphosis progression. OVERVIEW OF LITERATURE: Kyphoplasty can correct local kyphosis (fractured vertebra), but its efficacy is attenuated by adjacent fracture and/or disc height reduction with endplate damage. With these attenuating factors incorporated, a comparison between BKP and conservative treatment is necessary to verify the effect of BKP on kyphosis correction. METHODS: This study retrospectively analyzed 129 patients treated conservatively and 95 treated with BKP in our institution. The rate of new adjacent fracture occurrence was determined using Kaplan-Meier analysis. We examined the progression of local kyphosis in patients who underwent lateral X-ray after 1 year. Local kyphosis was measured as an angle between higher end plate of the vertebra above and lower end plate of the vertebra below the fractured vertebra. The comparison included 45 patients treated conservatively and 58 treated with BKP. RESULTS: The incidence of new adjacent fracture at 1 year was 7.3% in the conservative treatment group and 23.2% in the BKP group (p<0.001), while the progression of local kyphosis at 1 year was 5.7°±4.7° and 3.2°±4.6°, respectively (p=0.01). Relative to conservative treatment, local kyphosis did not progress after BKP, despite the higher incidence of adjacent fracture. Local kyphosis progressed in cases with adjacent fracture compared with those without adjacent fracture (6.0°±4.3° vs. 2.1°±4.3°, p=0.003), and fractured vertebral instability was found to be a risk factor for adjacent fracture in BKP. CONCLUSIONS: Compared with the conservative treatment, BKP suppressed the progression of local kyphosis. However, an adjacent fracture attenuated the BKP correction and was more frequently seen in patients with unstable vertebral fractures.

Lumbar lordosis does not correlate with pelvic incidence in the cases with the lordosis apex located at L3 or above.

PURPOSE: To test the hypothesis that the relationship between PI and L1-S1 lumbar lordosis (LL) is always positive, even in cases with different lumbar sagittal profiles. METHODS: Standing whole-spine sagittal alignment was measured with EOS system in 100 healthy adults (46 men, 54 women, mean age 40.9 years). The apex of lumbar lordosis was defined as the most anterior lumbar vertebra or intervertebral disk from the gravity line determined by a force plate measurement. Subjects were stratified into three groups: the upper group with an apex between L1 and L3 (UppA, n = 19), the middle group with an apex from L3/4 to L4/5 (MidA, n = 67), and the lower group with an apex at L5 or below (LowA, n = 14). PI, PT, SS, thoracic kyphosis (TK), LL, SVA, T1 pelvic angle, and knee flexion angle were compared between the groups. The correlation between LL and PI in each group was also compared. RESULTS: PI and SS differed significantly between the three groups, and LL was significantly different between LowA and MidA and UppA. TK and KF did not differ significantly between groups. LL and PI were significantly positively correlated in the MidA and LowA groups, but not in the UppA group. CONCLUSION: Contrary to the hypothesis, the correlation coefficient between PI and LL was not significant in the cases with apex above L3, suggesting that the relationship between PI and LL is not always constant, and whole sagittal alignment should be taken into account. These slides can be retrieved under Electronic Supplementary Material.

The morphological relationship between lumbosacral transitional vertebrae and lumbosacral pedicle asymmetry.

INTRODUCTION: The clinical significance of lumbosacral transitional vertebrae (LSTV) has been reported. However, the association between LSTV and lumbosacral pedicle anatomical anomaly has not been investigated. We hypothesized that LSTV might be associated with lumbosacral anatomical anomaly. The purpose of this study was to examine the morphological association between LSTV and lumbosacral pedicle asymmetry (PA) using computed tomography (CT). METHODS: A retrospective review of CT images of 347 lumbosacral degenerative disease patients was performed. We divided the subjects into two groups: the normal and LSTV groups. LSTV was classified based on Castellvi's classification. PA was defined as a difference of more than 20° between the right and left angles of the pedicle. RESULTS: Seventy out of 347 lumbosacral degenerative disease patients (20.17%) were diagnosed with LSTV. In the normal group, only a 0.54% incidence of PA was seen; however, with respect to the LSTV group, a 9.29% incidence of PA was seen. A significant difference in PA incidence was observed between the groups (p < 0.001). Type IIIa and Type IV in the LSTV group showed a statistically significant PA incidence rate (p = 0.004 and p = 0.039, respectively). CONCLUSIONS: Our study demonstrated that there was a significant difference in the incidence of PA between LSTV subjects and normal subjects. Moreover, the incidence of PA was significantly higher in LSTV subjects with severe anomaly. These results suggested that lumbosacral spine anomaly might have a close relationship with the incidence of PA and lumbosacral nerve root asymmetry. Therefore, morphological evaluation of the pedicle is important for preoperative surgical management, especially in cases using pedicle screws. This information could lower the incidence of pedicle screw malposition when pedicle screws are inserted at the lumbosacral spine.

Does an osteoporotic vertebral fracture treated by balloon kyphoplasty successfully achieve bone union during the follow-up? A retrospective study with a minimum 2-year follow-up.

OBJECTIVE: To investigate whether bone union is achieved in osteoporotic vertebral fracture (OVF) patients who undergo balloon kyphoplasty (BKP). METHODS: Thirty-six vertebrae, which were followed-up for more than two years after BKP, were evaluated in the present study. Bone union was assessed by using CT scans and lateral X-ray films obtained in the sitting and supine positions. RESULTS: Twenty-seven vertebrae exhibited bone union at the final follow-up. The VAS scores improved in all cases. CONCLUSIONS: Unstable vertebrae after treatment may develop complications; thus special attention should be paid to the treated vertebrae until bone union has been achieved.

Does Modic Change Progresss With Age?

STUDY DESIGN: Cross-sectional imaging study. OBJECTIVE: The aim of this study was to clarify the trend in the generation distinctions about the prevalence of Modic change (MC) including elderly patients. SUMMARY OF BACKGROUND DATA: MC has been discussed regarding its clinical significance, relationship with low back pain, suitable treatments, prevalence, and natural history. However, previous reports have focused on younger subjects, with few studies conducted in elderly patients. If MC is actually a progressive condition of a patient, then it should become more common as the patient ages. We herein report the distribution of MC across several age groups. METHODS: Patients who underwent lumbar magnetic resonance imaging (MRI) in our institution from April 2013 to March 2015 were recruited. MC was assessed using T1- and T2-weighted magnetic resonance imaging (MRI) and divided into Modic types (MT) 1, 2, and 3, and mixed type. Trends in the prevalence of MC were analyzed based on age. RESULTS: We ultimately included 585 patients of an initial 937 who underwent lumbar MRI. The mean age was 65 years. MC was identified in 36.0% of the patients. The prevalence of MC by age was 0% for those in their 10 s, 10% for those in their 20 s, 33% for those in their 30 s, 27% for those in their 40 s, 32% for those in their 50 s, 44% for those in their 60 s, 42% for those in their 70 s, and 26% for those in their 80 s. By type, 3.3% were MT1, 81.3% were MT2, 0.5% were MT3, and 14.8% were mixed type. CONCLUSION: The prevalence of MC increased with age to some degree, with the highest frequency observed in individuals in their 60 s before declining in those in their 70 s and 80 s. These findings suggest that MC might not simply progress with age, particularly after the seventh decade of life. LEVEL OF EVIDENCE: 4.

Simultaneous Use of Both Bilateral Intralaminar and Pedicle Screws for C2 Stabilization.

Four patients underwent stabilization surgery using both bilateral C2 pedicle screw (PS) and intralaminar screw (LS). Neural and vascular injury resulting from incorrect screw placement was assessed using computed tomography (CT). The evaluation of bone union was assessed by lateral flexion-extension X-ray films and CT. The symptoms were improved in all patients. There were no intraoperative complications. Furthermore, there were no cases of neurological worsening or vascular injury from incorrect screw placement. Failure of instrumentation or screw loosening during the follow-up period did not occur in any of the patients. All cases had accomplished bone union at the final follow-up. Theoretically, the stabilization technique using both bilateral C2 PS and LS at the same time can provide more stability than any other single technique. Simultaneous use of both bilateral C2 PS and LS is potentially a good choice for surgical repair.

A new sagittal parameter to estimate pelvic tilt using the iliac cortical density line and iliac tilt: a retrospective X-ray measurement study.

BACKGROUND: When spinal kyphosis increases, the compensatory mechanism activates and the pelvic position changes. Increasing the pelvic tilt, which is the orientation of the pelvis with respect to the femoral head, is known to associate with the clinical symptoms in kyphosis in the aging population. It is often difficult to detect the femoral head on radiographs, limiting the ability to determine the pelvic tilt. Therefore, there is a need to establish another parameter independent of the femoral head which closely correlates with the pelvic tilt. METHODS: Eighty-two adult patients with full-length lateral standing spine radiographs were recruited (mean age: 73.0 years). A new parameter, the iliac cortical density line (a component of the arcuate line of the ilium) and the iliac tilt (defined as the angle between the iliac cortical density line and the vertical), was analyzed to determine the correlation with the pelvic tilt. RESULTS: Both the pelvic tilt (PT) and iliac tilt (IT) could be identified in 67 patients, and a significant correlation was observed between the PT and IT (r = 0.86, P < 0.0001). The PT could be estimated using the following formula: PT = IT - 12.9 (in females), PT = IT - 16.7 (in males). CONCLUSIONS: The iliac tilt, which can be easily and directly measured using the iliac cortical density line, is a new parameter that can reliably estimate the pelvic tilt even when the femoral head is not detectable on the radiograph.

A Retained Epidural Catheter Fragment Treated by Surgery.

The breakage of an epidural catheter is an extremely rare complication. We describe a unique case where a retained epidural catheter fragment after epidural anesthesia was treated by surgery. The epidural catheter broke during its removal, requiring surgery to remove the retained catheter. Intraoperatively, the removal of the catheter was attempted by simple traction, but was impossible because of the adhesion. The adhesion of the dura mater surface was carefully exfoliated and the successful removal of the catheter was accomplished. Conventionally, it was said that this follow-up was enough for the retained catheter. However, if a catheter is retained within the spinal canal, surgical removal should thus be considered before the adhesion advances.

Spontaneous regression of posterior epidural migrated lumbar disc fragments: case series.

BACKGROUND CONTEXT: Posterior epidural migrated lumbar disc fragments is an extremely rare disorder. Surgical treatment was performed in all reported cases. To the best of our knowledge, there are no reported cases of the use of conservative treatment for posterior epidural migrated lumbar disc fragments. PURPOSE: To report the possibility of a spontaneous regression of posterior epidural migrated lumbar disc fragments. STUDY DESIGN: Case series. METHODS: Four patients with posterior epidural migrated lumbar disc fragments were treated at Karatsu Red Cross Hospital between April 2008 and August 2010. Spontaneous regression of the posterior epidural migrated lumbar disc fragments with relief of symptoms was observed on magnetic resonance imaging (MRI) in three cases. Another patient underwent surgical treatment. The present and previously reported cases of posterior epidural migrated lumbar disc fragments were analyzed with respect to patient age, imaging features on MRI, the level of the lesion, clinical symptoms, treatment, and outcomes. RESULTS: Conservative treatment was successful, and spontaneous lesion regression was seen on MRI with symptom relief in three cases. CONCLUSIONS: Although posterior epidural migrated lumbar disc fragment cases are generally treated surgically, the condition can regress spontaneously over time, as do sequestrated disc fragments. Spontaneous regression of lumbar disc herniations is a widely accepted observation at present. Posterior epidural migrated lumbar disc fragments fall under the sequestrated type of disc herniation. In fact, the course of treatment for posterior epidural migrated lumbar disc fragments should be determined based on the symptoms and examination findings, as in cases of ordinary herniation. However, providing early surgical treatment is important if the patient has acute cauda equina syndrome or the neurologic symptoms worsen over time.

A shallow chest correlates with the aortic position in the normal spine: features resembling those observed in structural scoliosis.

BACKGROUND: Right thoracic curvature, rib cage deformities and aortic left shift are features of adolescent idiopathic scoliosis that are correlated with each other. We recently reported that disturbance of ribcage development results in progressive thoracic scoliosis in mice. Recently, it has been confirmed that the normal spine exhibits right thoracic curvature and rib cage deformities and that these deformities worsen during the adolescent period. The purpose of this study was to examine whether rib cage deformities correlate with thoracic side curvature in the normal spine, as observed in scoliosis, which is important basic knowledge needed to elucidate the causative factors of adolescent idiopathic scoliosis. METHODS: To examine the relationship between rib cage deformities and thoracic side curvature in the normal spine, CT scans of 148 consecutive adult females were examined. The anteroposterior chest dimension, aortic location and rib cage rotation were measured on CT scans obtained at the T8 level. The thoracic side curvature (T5-T12) was also measured on chest radiographs. RESULTS: The anteroposterior chest dimension exhibited a significant correlation with aortic left shift. The aortic location and rib cage rotation were correlated, and the rib cage rotation and thoracic side curvature were correlated. CONCLUSIONS: There was a significant correlation between a shallow chest and the aortic position, between the aortic position and the rib cage rotation and between the rib cage rotation and the thoracic side curvature in the normal spine. These findings suggest the possibility that rib cage development is one of the causative factors of adolescent idiopathic scoliosis.

Instability of the Vertebrae Remains following Balloon Kyphoplasty.

Study Design Retrospective cohort study. Objectives The mechanism underlying the pain relief observed following balloon kyphoplasty (BKP) to vertebral compression fractures is reported to involve stabilization of the fractured vertebrae. However, whether fixation of the vertebrae was achieved immediately after BKP has not been investigated. The purpose of this study was to assess fixation of the vertebrae immediately after BKP and whether the instability was related to visual analog scale (VAS) scores. Methods Thirty-eight patients with vertebrae that were evaluated on lateral roentgenkymography within 1 week after BKP were recruited. Instability was defined as a cleft observed between the cement and end plate of the vertebra in the supine position that disappeared in the sitting position, and the posterior wall height of the vertebra was reduced in the sitting position. Results Instability of the vertebrae immediately after BKP was observed in 17 cases. VAS scores improved in all cases, and no significant differences were observed with or without instability. Conclusions The mechanism of rapid pain relief following BKP was not strong fixation but some degree of stabilization or other factors. We suggest that more research is needed about the mechanism of pain relief following BKP in the future.

Ordinary disc herniation changing into posterior epidural migration of lumbar disc fragments confirmed by magnetic resonance imaging: a case report of a successful endoscopic treatment.

The posterior epidural migration of lumbar disc fragments is an extremely rare event with an unknown pathogenesis. To the best of our knowledge, there are no previously reported cases of a change of ordinary disc herniation into the posterior epidural migration of lumbar disc fragments as confirmed by magnetic resonance imaging (MRI). A 26-year-old male presented to our department complaining of left buttock and lateral leg pain. An ordinary herniation was shown in the first MRI. The patient's unilateral symptoms changed into bilateral symptoms while awaiting admission to the hospital. Posterior migrated lumbar disc fragments were shown in the second MRI taken at the time of admission. Microendoscopic surgery providing a detailed observation of the region was performed. Our case indicates that an ordinary lumbar disc herniation may lead to the posterior migration of lumbar disc fragments, and that microendoscopic surgery may provide a treatment.

Translaminar microendoscopic herniotomy for cranially migrated lumbar disc herniations encroaching on the exiting nerve root in the preforaminal and foraminal zones.

STUDY DESIGN: Case series. PURPOSE: The aim of this study was to describe translaminar microendoscopic herniotomy (TL-MEH) for cranially migrated lumbar disc herniations encroaching on the exiting nerve root in the preforaminal and foraminal zones and to report preliminary results of the procedure. OVERVIEW OF LITERATURE: Conventional interlaminar approaches for preforaminal and foraminal lumbar disc herniations result in extensive removal of the lamina and facet joint to remove disc fragments safely. More destructive approaches increase the risk of postoperative segmental instability. METHODS: TL-MEH is a minimally invasive procedure for herniotomy via the translaminar approach using a microendoscopic technique. TL-MEH was performed in seven patients with a cranially migrated lumbar disc herniation encroaching on the exiting nerve root. The disc fragments were located in the preforaminal zone in four patients, and in the preforaminal and foraminal zones in three. RESULTS: All patients experienced immediate relief from symptoms after surgery and satisfactory results at the final follow-up. Surgical complications, such as a dural tear, nerve injury, and surgical site infection, were not investigated. CONCLUSIONS: TL-MEH seemed to be an effective and safe alternative minimally invasive surgical option for patients with a cranially migrated lumbar disc herniation encroaching the exiting nerve root in the preforaminal and foraminal zones.

A new method for measuring torsional deformity in scoliosis.

BACKGROUND: The importance of spinal rotational and torsional deformity in the etiology and the management of scoliosis are well-recognized. For measuring the posterior spinal component rotation, Ho's method was reported to be reliable. However, there is no practical method to measure the anterior spinal component rotation. Moreover, there is also no method to quantify the spinal torsional deformity in scoliosis. The goal of this study is to characterize scoliosis and its deformity to hypothesize the etiology and the development of scoliosis, and to establish a new method for the measurement of the vertebral body rotation and spinal torsional deformity in scoliosis using CT scans. METHODS: Pre-operative CT scans of 25 non-congenital scoliosis patients were recruited and the apical vertebral rotation was measured by a newly developed method and Ho's method. Ho's method adopts the laminae as the rotational landmark. For a new method to measure the apical vertebral rotation, the posterior point just beneath each pedicle was used as a landmark. For quantifying the spinal torsional deformity angle, the rotational angle difference between the two methods was calculated. RESULTS: Intraobserver and interobserver reliability analyses showed both methods to be reliable. Apical vertebral rotation revealed 13.9 ± 6.8 (mean ± standard deviation) degrees by the new method and 7.9 ± 6.3 by Ho's method. Right spinal rotation was assigned a positive value. The discrepancy of rotation (6.1 ± 3.9 degrees), meaning that the anterior component rotated more than the posterior component, was considered to express the spinal torsional deformity to the convex side. CONCLUSIONS: We have developed an easy, reliable and practical method to measure the rotation of the spinal anterior component using a CT scan. Furthermore, we quantified the spinal torsional deformity to the convex side in scoliosis by comparing the rotation between the anterior and posterior components.

Endoscopic decompression for intraforaminal and extraforaminal nerve root compression.

OBJECTIVE: The purpose of this study was to evaluate the outcome of endoscopic decompression surgery for intraforaminal and extraforaminal nerve root compression in the lumbar spine. METHODS: The records from seventeen consecutive patients treated with endoscopic posterior decompression without fusion for intaforaminal and extraforaminal nerve root compression in the lumbar spine (7 males and 10 females, mean age: 67.9 ± 10.7 years) were retrospectively reviewed. The surgical procedures consisted of lateral or translaminal decompression with or without discectomy. The following items were investigated: 1) the preoperative clinical findings; 2) the radiologic findings including MRI and computed tomography-discography; and 3) the surgical outcome as evaluated using the Japanese Orthopaedic Association scale for lower back pain (JOA score). RESULTS: All patients had neurological findings compatible with a radiculopathy, such as muscle weakness and sensory disturbance. MRI demonstrated the obliteration of the normal increased signal intensity fat in the intervertebral foramen. Ten patients out of 14 who underwent computed tomography-discography exhibited disc protrusion or herniation. Selective nerve root block was effective in all patients. During surgery, 12 patients were found to have a protruded disc or herniation that compressed the nerve root. Sixteen patients reported pain relief immediately after surgery. CONCLUSIONS: Intraforaminal and extraforaminal nerve root compression is a rare but distinct pathological condition causing severe radiculopathy. Endoscopic decompression surgery is considered to be an appropriate and less invasive surgical option.

Prevalence and clinical features of intraspinal facet cysts after decompression surgery for lumbar spinal stenosis.

OBJECT: Although many cases of primary intraspinal facet cysts in the lumbar spine have been reported, there have only been a few reports of postoperative intraspinal facet cysts in the lumbar spine. The purpose of this study was to investigate the prevalence and clinical features of postoperative intraspinal facet cysts in the lumbar spine. METHODS: Data from 81 patients undergoing microendoscopic posterior decompression to treat lumbar spinal stenosis were reviewed. The development of a postoperative intraspinal facet cyst was observed using MR imaging during 1 year after surgery. If the patient demonstrated a postoperative intraspinal facet cyst, additional MR imaging was performed to evaluate the natural course of the cyst. Furthermore, the authors conducted a comparative evaluation to identify the factors associated with the causes of cyst development. RESULTS: A postoperative intraspinal facet cyst developed in 7 patients (8.6%) during 1 year after surgery. Spondylotic spinal stenosis, degenerative spondylolisthesis, and degenerative scoliosis were revealed before surgery in 2, 4, and 1 patient, respectively. In 5 patients, the cysts developed within 3 months after surgery. Although 3 patients exhibited symptoms caused by cyst development, all symptoms were relieved by conservative treatment. On radiographic evaluations, postoperative segmental spinal instability, including a progression of spondylolisthesis and disc degeneration, was revealed in 6 (86%) of the 7 patients. Spontaneous regression of the cysts was observed in 5 (71%) of these 7 patients. On comparative evaluation of patients with and without postoperative intraspinal facet cysts, the presence of segmental spinal instability before surgery (including degenerative spondylolisthesis) and the appearance of postoperative segmental spinal instability were related to the development of the cysts. CONCLUSIONS: The prevalence of postoperative intraspinal facet cysts, including asymptomatic cysts, was 8.6% during 1 year after decompression surgery for lumbar spinal stenosis. The development of postoperative intraspinal facet cysts was related to the presence of segmental spinal instability before surgery (including degenerative spondylolisthesis) and postoperative segmental spinal instability, including a progression of spondylolisthesis and disc degeneration after surgery. A postoperative intraspinal facet cyst, which can be expected to regress spontaneously with a probability > 50%, should be recognized as one of the postoperative complications of decompression surgery for lumbar spinal stenosis.

Evaluation of postoperative spinal epidural hematoma after microendoscopic posterior decompression for lumbar spinal stenosis: a clinical and magnetic resonance imaging study.

OBJECT: The incidence of postoperative spinal epidural hematoma (SEH) is low, and to the best of the authors' knowledge, no researchers have evaluated its actual incidence and clinical features. The purpose of this study was to investigate the clinical consequences of SEH after microendoscopic posterior decompression (MEPD) in patients with lumbar spinal stenosis. METHODS: Data obtained in 30 patients undergoing MEPD for lumbar spinal stenosis were reviewed. At 1 week after surgery, magnetic resonance (MR) imaging documented SEHs in 10 patients (33% [Group 1]) and no evidence of SEHs in 20 patients (67% [Group 2]). The authors compared MR imaging findings, postoperative morbidities, and clinical outcomes between the groups. Three Group 1 patients had symptomatic SEHs. All symptoms were mild without associated neurological deterioration and spontaneously subsided within 3 weeks of surgery. Magnetic resonance imaging demonstrated spontaneous regression of the SEH in all patients at 3 months after surgery. In Group 1 patients, however, the authors observed less expansion of the dural sac after 1 year despite sufficient widening of the osseous spinal canal. Low-back pain within 1 week of surgery was moderate in Group 1 and mild in Group 2. Improvements at the final follow up were greater in Group 2 patients. CONCLUSIONS: The incidence of postoperative SEHs may be greater than reported. Postoperative SEHs caused poor expansion of the dural sac despite its spontaneous regression. In addition, postoperative SEHs caused a delay in the patient's recovery and led to a poor clinical improvement. The prevention of postoperative SEHs might be required to prevent not only neurological deterioration but also a delay in the patient's recovery.