Accuracy of percutaneous pedicle screw placement with 3-dimensional fluoroscopy-based navigation: Lateral decubitus position versus prone position.

The accuracy of percutaneous pedicle screw (PSS) placement in the lateral decubitus position has seldom been reported. This study aimed to retrospectively compare the accuracy of PPS placement with 3-dimensional (3D) fluoroscopy-based navigation in 2 cohorts of patients who underwent surgery in the lateral decubitus or prone positions at our single institute. A total of 265 consecutive patients underwent spinal surgery with PPS from T1 (thoracic 1) to S (sacrum) under the 3D fluoroscopy-based navigation system at our institute. Patients were divided into 2 groups based on their intraoperative patient positioning: lateral decubitus (Group L) or prone (Group P). A total of 1816 PPSs were placed from T1 to S, and 76 (4.18%) PPSs were assessed as deviated PPS. Twenty-one of 453 (4.64%) PPSs in Group L deviation and 55 of 1363 (4.04%) PPSs in Group P had deviated PPS, but with not significant difference (P = .580). In Group L, although the PPS deviation rate was not significantly different between the upside and downside PPS, the downside PPS significantly deviated toward the lateral side compared with the upside PPS. The safety and efficacy of PPS insertion in the lateral decubitus position were similar to those in the conventional prone position.

The Prevalence and Characteristics of Diffuse Idiopathic Skeletal Hyperostosis (DISH): A Cross-Sectional Study of 1519 Japanese Individuals.

Background: Diffuse idiopathic skeletal hyperostosis (DISH) is a pathology characterized by enthesis ossification, but there have been few reports on epidemiological surveys. This report presents a cross-sectional survey of DISH from thoracic to sacral spine in patients at the tertiary emergency medical center. Methods: The patients were divided into DISH (+) group and DISH (−) group for a retrospective comparative study. The primary outcome measures were the frequency of DISH and the patient demographic data, the secondary outcome measures were the previous medical history (diabetes mellitus, cardiovascular disease), the extent of aortic calcification, the frequency of hyperostosis around the costovertebral joint and the mortality rate within 3 months of the initial examination. Results: This survey examined a total of 1519 patients. There were 265 cases (17.4%) in the DISH (+) group and 1254 cases in DISH (−) group. The prevalence of DISH was concentrated at the thoracolumbar junction, particularly at T9. The mean age, ratio of male and hyperostosis around the costovertebral joint were significantly higher in the DISH (+) group (p < 0.001), but there was no significant difference in other variables. Conclusions: The pathology of DISH might involve the effects of age-related changes or biomechanical effects.

The impact of the lateral decubitus position in the perioperative period on posterior fixation for thoracolumbar fracture with ankylosing spinal disorder.

OBJECTIVE: Patients with ankylosing spinal disorders (ASDs), such as ankylosing spondylitis and diffuse idiopathic skeletal hyperostosis, often have rigid kyphosis of the spine. The fracture site is sometimes unintentionally displaced when surgery is conducted with the patient prone. To prevent this incident, the authors adopted the lateral decubitus position for patients intraoperatively for this pathology. The aim of this study was to retrospectively assess the impact of the lateral decubitus position in the perioperative period on posterior fixation for thoracolumbar fractures with ASD. METHODS: Thirty-seven consecutive patients who underwent posterior instrumentation for thoracolumbar fracture with ASD at the authors' institute were divided into 15 lateral decubitus positions (group L) and 22 prone positions (group P). Surgical time, estimated blood loss (EBL), number of levels fused, perioperative complications, length of stay (LOS), ratio of fracture voids, and ratio of anterior wall height were investigated. The ratio of fracture void and the ratio of anterior wall height were the radiological assessments showing a degree of reduction in vertebral fracture on CT. RESULTS: Age, sex, BMI, fracture level, and LOS were similar between the groups. Levels fused and EBL were significantly shorter and less in group L (p < 0.001 and p = 0.04), but there was no significant difference in surgical time. The complication rate was similar, but 1 death within 90 days after surgery was found in group P. The ratio of fracture voids was 85.4% ± 12.8% for group L and 117.5% ± 37.3% for group P. A significantly larger number of patients with a fracture void ratio of 100% or less was found in group L (86.7% vs 36.4%, p = 0.002). The ratio of anterior wall height was 107.5% ± 12.3% for group L and 116.9% ± 18.8% for group P. A significantly larger number of patients with the anterior wall height ratio of 100% or less was also found in group L (60.0% vs 27.3%, p = 0.046). CONCLUSIONS: The results of this study suggest that the lateral decubitus position can be expected to have an effect on closing or maintaining the fracture void or a preventive effect of intraoperative unintentional extension displacement of the fractured site, which is often seen in the prone position during surgery for thoracolumbar fractures involving ASD.

Simultaneous Anterior and Posterior Release in Lateral Decubitus Position for Rigid Adult Spinal Deformity: A Technical Note and 2 Case Reports.

BACKGROUND: Correction surgery for rigid adult spinal deformity usually involves a complex 360° osteotomy, multiple intraoperative position changes, and staged surgery. Moreover, there is a lack of consensus regarding the surgical strategy for this pathology. We report the technical advantages of a simultaneous anterior and posterior release only in the lateral decubitus position to reduce surgical invasiveness in two case reports. CASE DESCRIPTION: A 76-year-old woman and an 80-year-old woman presented with significant spinal imbalance and segmental fusion in the anterior and posterior columns around the apex of the lumbar spinal curvature. We conducted this procedure for these patients at the first stage of spinal corrective surgery to achieve 360° osteotomy. A long posterior fusion surgery was performed after 1 week. The mean values of the central sacral vertical line, pelvic incidence minus lumbar lordosis, sagittal vertical axis, and pelvic tilt improved substantially postoperatively: central sacral vertical line, from 51.0 to 7.5 mm; pelvic incidence minus lumbar lordosis, from 27.5° to 0.5°, sagittal vertical axis, from 107.6 to 14 mm; pelvic tilt, from 34.0° to 13.0°. The mean surgical time and blood loss in the first- and second-stage operations were 242.1 minutes and 702 mL and 315.5 minutes and 549 mL, respectively, and no perioperative complications occurred. CONCLUSIONS: Simultaneous 360° segmental release in the lateral decubitus position without repositioning can make it possible to acquire satisfactory correction and reduce surgical invasiveness compared with the conventional procedure for adult spinal deformity.

Effect of Early vs Delayed Surgical Treatment on Motor Recovery in Incomplete Cervical Spinal Cord Injury With Preexisting Cervical Stenosis: A Randomized Clinical Trial.

Importance: The optimal management for acute traumatic cervical spinal cord injury (SCI) is unknown. Objective: To determine whether early surgical decompression results in better motor recovery than delayed surgical treatment in patients with acute traumatic incomplete cervical SCI associated with preexisting canal stenosis but without bone injury. Design, Setting, and Participants: This multicenter randomized clinical trial was conducted in 43 tertiary referral centers in Japan from December 2011 through November 2019. Patients aged 20 to 79 years with motor-incomplete cervical SCI with preexisting canal stenosis (American Spinal Injury Association [ASIA] Impairment Scale C; without fracture or dislocation) were included. Data were analyzed from September to November 2020. Interventions: Patients were randomized to undergo surgical treatment within 24 hours after admission or delayed surgical treatment after at least 2 weeks of conservative treatment. Main Outcomes and Measures: The primary end points were improvement in the mean ASIA motor score, total score of the spinal cord independence measure, and the proportion of patients able to walk independently at 1 year after injury. Results: Among 72 randomized patients, 70 patients (mean [SD] age, 65.1 [9.4] years; age range, 41-79 years; 5 [7%] women and 65 [93%] men) were included in the full analysis population (37 patients assigned to early surgical treatment and 33 patients assigned to delayed surgical treatment). Of these, 56 patients (80%) had data available for at least 1 primary outcome at 1 year. There was no significant difference among primary end points for the early surgical treatment group compared with the delayed surgical treatment group (mean [SD] change in ASIA motor score, 53.7 [14.7] vs 48.5 [19.1]; difference, 5.2; 95% CI, -4.2 to 14.5; P = .27; mean [SD] SCIM total score, 77.9 [22.7] vs 71.3 [27.3]; P = .34; able to walk independently, 21 of 30 patients [70.0%] vs 16 of 26 patients [61.5%]; P = .51). A mixed-design analysis of variance revealed a significant difference in the mean change in ASIA motor scores between the groups (F1,49 = 4.80; P = .03). The early surgical treatment group, compared with the delayed surgical treatment group, had greater motor scores than the delayed surgical treatment group at 2 weeks (mean [SD] score, 34.2 [18.8] vs 18.9 [20.9]), 3 months (mean [SD] score, 49.1 [15.1] vs 37.2 [20.9]), and 6 months (mean [SD] score, 51.5 [13.9] vs 41.3 [23.4]) after injury. Adverse events were common in both groups (eg, worsening of paralysis, 6 patients vs 6 patients; death, 3 patients vs 3 patients). Conclusions and Relevance: These findings suggest that among patients with cervical SCI, early surgical treatment produced similar motor regain at 1 year after injury as delayed surgical treatment but showed accelerated recovery within the first 6 months. These exploratory results suggest that early surgical treatment leads to faster neurological recovery, which requires further validation. Trial Registration: ClinicalTrials.gov Identifier: NCT01485458; umin.ac.jp/ctr Identifier: UMIN000006780.

Spinopelvic fixation with retention of external fixation in a lateral position for unstable pelvic fracture.

Anterior external fixation (EF), as the primary treatment for unstable pelvic fractures, is performed with patients in the supine position. In most cases, however, definitive surgery for posterior fixation is performed first in the prone position without EF. We report the case of a patient with unilateral and vertically unstable pelvic fracture whom we had treated with minimally invasive spinopelvic fixation, with retention of the anterior EF in a lateral position. Reduction of the residual displacement was performed with percutaneous spinal instrumentation, and acceptable reduction was achieved. At the 13-month follow-up, the functional outcome, calculated using the Majeed Score, was 87 points. The plain radiograph showed good bone union, except for the right superior pubic ramus. The radiological outcome, measured using the Matta rating, was excellent. Thus, retaining the EF facilitates safe and accurate reduction without major surgical complications and may offer surgeons an additional management option for such fractures.

Treatment of Thoracolumbar Spinal Fracture Accompanied by Diffuse Idiopathic Skeletal Hyperostosis Using Transdiscal Screws for Diffuse Idiopathic Skeletal Hyperostosis: Preliminary Results.

STUDY DESIGN: This retrospective case series enrolled 13 patients who underwent posterior fixation with both transdiscal screws for diffuse idiopathic skeletal hyperostosis (TSDs) and pedicle screws (PSs) to treat spinal injury accompanied by diffuse idiopathic skeletal hyperostosis (DISH). PURPOSE: To describe the usefulness, feasibility, and biomechanics of TSD. OVERVIEW OF LITERATURE: Vertebral bodies accompanied by DISH generally have lower bone mineral density than normal vertebral bodies because of the stress shielding effect. This phenomenon tends to makes screw fixation challenging. To our knowledge, solutions for this issue have not previously been reported. METHODS: Patients were assessed using the data on surgical time, estimated intraoperative blood loss, mean number of stabilized intervertebral segments, number of screws used, perioperative complications, union rate, and the three-level EuroQol five-dimensional questionnaire (EQ5D-3L) score at the final follow-up. The Hounsfield unit (HU) values of the screw trajectory area, and the actual intraoperative screw insertion torque of TSDs and PSs were also analyzed and compared. RESULTS: The surgical time and estimated intraoperative blood loss were 165.9±45.5 minutes and 71.0±53.4 mL, respectively. The mean number of stabilized intervertebral segments was 4.6±1.0. The number of screws used was 4.9±1.3 for TSDs and 3.0±1.4 for PSs. One death occurred after surgery. The union rate and EQ5D-3L scores were 100% and 0.608±0.128, respectively. The HU value and actual intraoperative screw insertion torque of TSDs were significantly better than those of PSs (p<0.001, p=0.033). CONCLUSIONS: We were able to achieve stable surgical outcomes using the combination of TSDs and PSs. The HU value and actual intraoperative screw insertion torque were significantly higher for TSDs than for PSs. Based on these results, when treating thoracolumbar spinal fractures accompanied by DISH in elderly populations, the TSD could be a stronger anchor than the PS.

The usefulness and safety of the simultaneous parallel anterior and posterior combined lumbar spine surgery using intraoperative 3D fluoroscopy-based navigation (SPAPS).

BACKGROUND: The combined anterior-posterior surgery in the lateral decubitus position generally needs the intraoperative repositioning. However, prolonged surgical time and increased medical costs due to intraoperative repositioning have been problematic. In recent years, there have been reports of combined anterior-posterior procedure with a single position performing anterior and posterior fixation consecutively where the patient remains in the lateral decubitus position (single surgeon method-SS method). We had further advanced this method, and have adopted the Simultaneous Parallel Anterior and Posterior combined lumbar spine Surgery using intraoperative 3D fluoroscopy-based navigation (SPAPS method), where anterior and posterior procedure are performed independently by two spine surgeons. METHODS: 66 cases that underwent SPAPS method (n=37) and SS method (n=29) from 2015 to 2019 at single institution were concluded in this study. The pre- and post-operative changes in the following were compared retrospectively between the two groups: surgical factors and clinical evaluations including JOA back pain evaluation questionnaire (JOABPEQ), visual analogue scale (VAS) on lower back pain, buttock/lower limb pain, and buttock/lower limb numbness, and Roland-Morris disability questionnaire (RDQ). RESULTS: The SPAPS method was able to significantly reduce the surgical time (p=0.0025) compared to the SS method, and allowed a reduction of approximately 24.4 minutes per segment. The estimated blood loss were similar in both groups, and with regards to post-operative outcomes, both groups improved equally well. The rates of screw deviation and fusion were also similar. CONCLUSIONS: In the case of performing the combined anterior-posterior surgery under a single position, the anterior and posterior procedure can be performed independently and simultaneously by two spine surgeons by utilizing the 3D fluoroscopy-based navigation. The surgical time can be significantly reduced by approximately 24.4 minutes per segment comparing to the SS method.

Radiation Exposure to the Hand of a Spinal Interventionalist during Fluoroscopically Guided Procedures.

STUDY DESIGN: Prospective study. PURPOSE: During fluoroscopically guided spinal procedure, the hands of spinal surgeons are placed close to the field of radiation and may be exposed to ionizing radiation. This study directly measured the radiation exposure to the hand of a spinal interventionalist during fluoroscopically guided procedures. OVERVIEW OF LITERATURE: Fluoroscopically guided spinal procedures have been reported to be a cause for concern due to the radiation exposure to which their operators are exposed. METHODS: This prospective study evaluated the radiation exposure of the hand of one spinal interventionalist during 52 consecutive fluoroscopic spinal procedures over a 3-month period. The interventionalist wore three real-time dosimeters secured to the right forearm, under the lead apron over the chest, and outside the lead apron over the chest. Additionally, one radiophotoluminescence glass dosimeter was placed under the lead apron over the left chest and one ring radiophotoluminescence glass dosimeter was worn on the right thumb. The duration of exposure and radiation dose were measured for each procedure. RESULTS: The average radiation exposure dose per procedure was 14.9 µSv, 125.6 µSv, and 200.1 µSv, inside the lead apron over the chest, outside the lead apron over the chest, and on the right forearm, respectively. Over the 3-month period, the protected radiophotoluminescence glass dosimeter over the left chest recorded less than the minimum reportable dose, whereas the radiophotoluminescence glass ring dosimeter recorded 368 mSv for the thumb. CONCLUSIONS: Our findings indicated that the cumulative radiation dose measured at the dominant hand may exceed the annual dose limit specified by the International Commission on Radiological Protection. Spinal interventionalists should take special care to limit the duration of fluoroscopy and radiation exposure.

Difficulties in removal of the titanium locking plate in Japan.

OBJECTIVE: This study was designed to evaluate the frequency of intraoperative complications associated with titanium locking compression plate (LCP) removal. DESIGN: Retrospective study. METHODS: Medical records were reviewed for surgical technique, plate types used, position and number of screws, time from internal fixation to plate removal, and intraoperative complications. Radiographs were reviewed to evaluate the position of the plates and screws and the accuracy of the screw direction. Mann-Whitney and Yates Chi-square tests were calculated with the level of significance at P < 0.05. RESULTS: All LCPs could be removed. Of the 342 locking head screws (LHSs), a total of 21 (6.1%) screws, 3 (2.0%) 5.0 mm screws (3/153) and 18 (10.7%) 3.5 mm screws (18/169), were difficult to remove. The frequency of difficulty associated with the 3.5 mm LHSs was significantly higher than that of the 5.0 mm LHSs (P < 0.01). The frequency of difficulty associated with the removal of LHSs at the diaphysis was higher than that of LHSs at the epiphysis (P < 0.01), especially with 3.5 mm LHSs. The mean age was significantly lower in the patients in whom removal was difficult (P < 0.05). Our analysis revealed that the frequency of removal difficulty was high when a 3.5 mm LHS was inserted into the diaphysis of young patients. CONCLUSIONS: We should recognize that the removal of LCPs can involve numerous problems and great care should be exercised, especially in cases involving 3.5 mm LHSs.

Dominant vertebral artery injury during posterior atlantoaxial transarticular screw fixation in a juvenile rheumatoid arthritis patient with atlantoaxial subluxation.

Many authors have reported on iatrogenic vertebral artery (VA) injury, but, to our knowledge, this is the first report of a dominant VA injury with compensatory blood flow from the hypoplastic VA. A 23-year-old woman with juvenile rheumatoid arthritis and atlantoaxial subluxation sustained injury to her dominant VA after occipitocervical fusion using transarticular screws. This did not result in lethal consequences due to compensation from her hypoplastic contralateral VA. Postoperative angiography, however, illustrated occlusion of the dominant left side, while the hypoplastic VA of the right side was enlarged. The patient experienced vertigo and loss of consciousness several times during rehabilitation. At the 4-year follow-up exam, bony fusion was observed, with no neurological deficits or correction loss. She had had no episodes of unconsciousness and no recurrence of any symptoms over the previous 3 years.

C2 lamina reconstruction using locking miniplate for the intradural tumor of the craniocervical junction (two case reports).

OBJECTIVE: To describe a technique for C2 lamina reconstruction using locking miniplates for the extirpation of spinal tumors in the craniocervical junction. Many spinal surgery cases in which lamina reconstructions have been performed using non-locking miniplates have been reported. However, there is only one report of the use of locking miniplates for lamina reconstruction in spinal tumor cases. METHODS: We performed C2 lamina reconstructions using locking miniplates in a patient with a spinal tumor and another with a cystic lesion. The clinical and radiologic features of both cases are reported, and the surgical technique is described. RESULTS: A 62-year-old female and a 30-year-old male were diagnosed with meningioma and a neurenteric cyst, respectively, in the craniocervical junction. Extirpation of these lesions was performed in combination with C2 lamina reconstruction and reattachment of the paraspinous muscle to the C2 spinous process. A follow-up examination at 1 year postoperatively demonstrated no significant change in the sagittal alignment of the cervical spine and a good postoperative course in both cases. Bony fusion was detected in both cases, and no implant failure occurred in either case. CONCLUSIONS: This procedure results in rigid fixation of the reimplanted C2 lamina and helps to restore the paraspinous muscles. For these reasons, it appears to be a useful surgical procedure for spinal tumors requiring C2 laminectomy and does not cause postoperative kyphosis of the cervical spine.

Novel magnetic resonance imaging evaluation for valgus instability of the knee caused by medial collateral ligament injury.

Instability of the knee after the medial collateral ligament (MCL) injury is usually assessed with the manual valgus stress test, even though, in recent years, it has become possible to apply magnetic resonance imaging (MRI) to the assessment of the damage of the ligament. The valgus instability of 24 patients (12 isolated injuries and 12 multiple ligament injuries) who suffered MCL injury between 1993 and 1998 was evaluated with the Hughston and Eilers classification, which involves radiographic assessment under manual valgus stress to the injured knees. We developed a novel system for classifying the degree of injury to the MCL by calculating the percentage of injured area based on MRI and investigated the relationship between this novel MRI classification and the magnitude of valgus instability by the Hughston and Eilers classification. There was a significant correlation between the 2 classifications (p=0.0006). On the other hand, the results using other MRI based classification systems, such as the Mink and Deutsch classification and the Petermann classification, were not correlated with the findings by the Hughston and Eilers classification in these cases (p0.05). Since MRI is capable of assessing the injured ligament in clinical practice, this novel classification system would be useful for evaluating the stability of the knee and choosing an appropriate treatment following MCL injury.

Spinal cord herniation into pseudomeningocele after traumatic nerve root avulsion: case report and review of the literature.

We present an extremely rare case of traumatic spinal cord herniation due to a brachial plexus avulsion injury and provide a review of the literature of spinal cord herniation. Spinal cord herniation is an uncommon condition that can occur spontaneously or as a result of surgery or trauma. This condition often presents with symptoms and signs as Brown-Séquard syndrome. Traumatic pseudomeningoceles after a brachial plexus avulsion injury have been reported. But transdural herniation of the spinal cord into this pseudomeningocele is an extremely rare and poorly documented condition. There is only two reports of this condition in a thoracic case. The authors report the case of a 22-year-old man presented with a 2-year history of quadriplegia. He was involved in a motorcycle accident, 3 years prior to his presentation. Four years after the initial right brachial plexus injury, he was not able to walk independently. Magnetic resonance imaging (MRI) and computerized tomography (CT) myelography revealed a lateral pseudomeningocele arising from the right C6-7 and C7-T1 intervetebral foramen and cervical spinal cord herniation into this pseudomeningocele. The patient underwent primary closure of pseudomeningocele to prevent spinal cord reherniation. He can walk with cane and use left arm unrestrictedly at the 2-year follow-up examination. Spinal cord herniation following traumatic nerve root avulsion is extremely rare but it should be considered in the differential diagnosis of patients presenting with delayed myelopathy or Brown-Séquard syndrome.

Comparative biomechanical analysis of an improved novel pedicle screw with sheath and bone cement.

STUDY DESIGN: A human cadaveric biomechanical study of fixation strength of an improved novel pedicle screw (NPS) with cement and a conventional screw. OBJECTIVE: To clarify whether the NPS has adequate fixation strength without leakage in vertebrae with low bone quality. SUMMARY OF BACKGROUND DATA: The fixation strength of pedicle screws decreases in frail spines of elderly osteoporotic patients. Augmentation of screw fixation with bone cement must be balanced against increased difficulty of screw removal and risk of cement leakage. We developed the NPS consisting of an internal screw and an outer sheath to mitigate the disadvantages of cement augmentation. METHODS: The T12 and L1 vertebrae obtained from 18 formalin preserved cadavers (11 males and 7 females; mean age, 82.7 y) were used. The mean bone mineral density was 0.39 +/- 0.14 g/cm2. The NPS was inserted into one pedicle of each vertebra and the control screw, a Compact CD2 screw, was inserted into the contralateral pedicle. Both screws were 6mm in diameter and 40 mm in length. Pull-out tests were performed at a crosshead speed of 10 mm/min. Cyclic loading tests were performed with a maximum 250 N load at 2 Hz until 30,000 cycles. RESULTS: Cement leakage did not occur in any of the specimens tested. The mean maximum force at pull-out was 760 +/- 344 N for the NPS and 346 +/- 172N for the control screw (P < 0.01). Loosening of 50% of the screws was observed after 17,000 cycles of the NPS and after 30 cycles of the control screw. The hazard ratio of loosening was 19.6 (95% confidence interval 19.3-19.9) (P < 0.001). CONCLUSIONS: The NPS showed a significantly higher mechanical strength than the control screw in both pull-out tests and cyclic loading tests. The NPS showed more than adequate strength without cement leakage.

Assessing range of cervical rotation after laminoplasty using axial CT.

PURPOSE: Although many authors have reported on cervical range of motion after laminoplasty, they have focused on flexion and extension based on lateral radiographs, not on axial rotation. In this study, we assessed cervical rotation from C1 to T1 after laminoplasty using computed tomography. PATIENTS AND METHODS: Eighteen consecutive patients with cervical myelopathy who had undergone laminoplasty were observed. Patient was placed in the supine position on the computed tomography scan table. After the scans in this neutral position were completed, the patient actively rotated his neck as far as possible taking care that the shoulders remained in the horizontal plane. We measured the C1 to T1, C1 to C2, and C2 to T1 rotation angles preoperatively, and at 2 weeks and 6 months after surgery. RESULTS: The average C1 to T1 rotation angles preoperatively were 46 degrees on the right and 45 degrees on the left. The percentage of C1 to C2 rotation during global cervical rotation (C1 to T1) was 62%. C1 to T1 rotation angle significantly decreased at two weeks after surgery but recovered to almost preoperative levels (11% decreases) by 6 months after surgery with no difference between right and left motion. The average C2 to T1 subaxial rotation angles did not significantly decreased after surgery. CONCLUSIONS: Rotation angle after laminoplasty decreased slightly at 2 weeks after surgery but recovered almost to preoperative levels by 6 months. Subaxial rotation (C2 to T1) angles did not significantly decreased after surgery.

Surgical results of sacral perineural (Tarlov) cysts.

The purpose of this study was to investigate the surgical outcomes and to determine indicators of the necessity of surgical intervention. Twelve consecutive patients harboring symptomatic sacral perineural cysts were treated between 1995 and 2003. All patients were assessed for neurological deficits and pain by neurological examination. Magnetic resonance of imaging, computerized tomography, and myelography were performed to detect signs of delayed filling of the cysts. We performed a release of the valve and imbrication of the sacral cysts with laminectomies in 8 cases or recapping laminectomies in 4 cases. After surgery, symptoms improved in 10 (83%) of 12 patients, with an average follow-up of 27 months. Ten patients had sacral perineural cysts with signs of positive filling defect. Two (17%) of 12 patients experienced no significant improvement. In one of these patients, the filling defect was negative. In conclusion, a positive filling defect may become an indicator of good treatment outcomes.