Artificial Intelligence for Neurosurgery : Current State and Future Directions

Artificial intelligence (AI) is a field of computer science that equips machines with human-like intelligence and enables them to learn, reason, and solve problems when presented with data in various formats. Neurosurgery is often at the forefront of innovative and disruptive technologies, which have similarly altered the course of acute and chronic diseases. In diagnostic imaging, such as X-rays, computed tomography, and magnetic resonance imaging, AI is used to analyze images. The use of robots in the field of neurosurgery is also increasing. In neurointensive care units, AI is used to analyze data and provide care to critically ill patients. Moreover, AI can be used to predict a patient’s prognosis. Several AI applications have already been introduced in the field of neurosurgery, and many more are expected in the near future. Ultimately, it is our responsibility to keep pace with this evolution to provide meaningful outcomes and personalize each patient’s care. Rather than blindly relying on AI in the future, neurosurgeons should gain a thorough understanding of it and use it to enhance their patient care.

Radiological Changes in Adjacent and Index Levels after Cervical Disc Arthroplasty

Purpose@#The purpose of this retrospective study was to evaluate radiological and clinical outcomes in patients undergoing cervical disc arthroplasty (CDA) for cervical degenerative disc disease. The results may assist in surgical decision-making and enable more effective and safer implementation of cervical arthroplasty. @*Materials and Methods@#A total of 125 patients who were treated with CDA between 2006 and 2019 were assessed. Radiological measurements and clinical outcomes included the visual analogue scale (VAS), the Neck Disability Index (NDI), and the Japanese Orthopaedic Association (JOA) myelopathy score assessment preoperatively and at ≥2 years of follow-up. @*Results@#The mean follow-up period was 38 months (range, 25–114 months). Radiographic data demonstrated mobility at both the index and adjacent levels, with no signs of hypermobility at an adjacent level. There was a non-significant loss of cervical global motion and range of motion (ROM) of the functional spinal unit at the operated level, as well as the upper and lower adjacent disc levels, compared to preoperative status. The cervical global and segmental angle significantly increased. Postoperative neck VAS, NDI, and JOA scores showed meaningful improvements after one- and two-level CDA. We experienced a 29.60% incidence of heterotrophic ossification and a 3.20% reoperation rate due to cervical instability, implant subsidence, or osteolysis. @*Conclusion@#CDA is an effective surgical technique for optimizing clinical outcomes and radiological results. In particular, the preservation of cervical ROM with an artificial prosthesis at adjacent and index levels and improvement in cervical global alignment could reduce revision rates due to adjacent segment degeneration.

Factors Affecting Postoperative Complications and Outcomes of Cervical Spondylotic Myelopathy with Cerebral Palsy : A Retrospective Analysis

Objective@#: Cervical surgery in patients with cervical spondylotic myelopathy (CSM) and cerebral palsy (CP) is challenging owing to the complexities of the deformity. We assessed factors affecting postoperative complications and outcomes after CSM surgery in patients with CP. @*Methods@#: Thirty-five consecutive patients with CP and CSM who underwent cervical operations between January 2006 and January 2014 were matched to 35 non-cerebral palsy (NCP) control patients. Postoperative complications and radiologic outcomes were compared between the groups. In the CP group, the Japanese Orthopaedic Association score; Oswestry neck disability index; modified Barthel index; and values for the grip and pinch, Box and Block, and Jebsen-Taylor hand function tests were obtained preand postoperatively and compared between those with and without postoperative complications. @*Results@#: Sixteen patients (16/35%) in the CP group and seven (7/35%) in the NCP group (p=0.021) had postoperative complications. Adjacent segment degeneration (p=0.021), postoperative motor weakness (p=0.037), and revisions (p=0.003) were significantly more frequent in the CP group than in the NCP group; however, instrument-related complications were not significantly higher in the CP group (7/35 vs. 5/35, p=0.280). The number of preoperative fixed cervical deformities were significantly higher in CP with postoperative complications (5/16 vs. 1/19, p=0.037). In the CP group, clinical outcomes were almost similar between those with and without postoperative complications. @*Conclusion@#: The occurrence of complications during the follow-up period was high in patients with CP. However, postoperative complications did not significantly affect clinical outcomes.

Factors Affecting Postoperative Complications and Outcomes of Cervical Spondylotic Myelopathy with Cerebral Palsy : A Retrospective Analysis

Objective@#: Cervical surgery in patients with cervical spondylotic myelopathy (CSM) and cerebral palsy (CP) is challenging owing to the complexities of the deformity. We assessed factors affecting postoperative complications and outcomes after CSM surgery in patients with CP. @*Methods@#: Thirty-five consecutive patients with CP and CSM who underwent cervical operations between January 2006 and January 2014 were matched to 35 non-cerebral palsy (NCP) control patients. Postoperative complications and radiologic outcomes were compared between the groups. In the CP group, the Japanese Orthopaedic Association score; Oswestry neck disability index; modified Barthel index; and values for the grip and pinch, Box and Block, and Jebsen-Taylor hand function tests were obtained preand postoperatively and compared between those with and without postoperative complications. @*Results@#: Sixteen patients (16/35%) in the CP group and seven (7/35%) in the NCP group (p=0.021) had postoperative complications. Adjacent segment degeneration (p=0.021), postoperative motor weakness (p=0.037), and revisions (p=0.003) were significantly more frequent in the CP group than in the NCP group; however, instrument-related complications were not significantly higher in the CP group (7/35 vs. 5/35, p=0.280). The number of preoperative fixed cervical deformities were significantly higher in CP with postoperative complications (5/16 vs. 1/19, p=0.037). In the CP group, clinical outcomes were almost similar between those with and without postoperative complications. @*Conclusion@#: The occurrence of complications during the follow-up period was high in patients with CP. However, postoperative complications did not significantly affect clinical outcomes.

Revision Surgery for a Failed Artificial Disc

Purpose@#This study aimed to present our experience with failures in C-TDR and revision surgery outcomes. @*Materials and Methods@#We retrospectively examined patients who underwent revision surgery due to the failure of C-TDR between May 2005 to March 2019. Thirteen patients (8 males and 5 females) were included in this study. The mean age was 46.1 years (range: 22–61 years), and the average follow-up period was 19.5 months (range: 12–64 months). The outcome measures of pre- and post-operative neck and arm pain using a visual analogue scale (VAS) and functional impairment were assessed using a modified Japanese Orthopedic Association (JOA) scale and the Neck Disability Index (NDI). @*Results@#The main complaints of patients were posterior neck pain (77%), radiculopathy (62%), and/or myelopathy (62%). The causes of failure of C-TDR were improper indications for the procedure, osteolysis and mobile implant use, inappropriate techniques, and postoperative infection. The most common surgical level was C5–6, followed by C4–5. After revision surgery, the neck and arm pain VAS (preoperative vs. postoperative: 5.46 vs. 1.31; 4.86 vs. 1.08), a modified JOA scale (14.46 vs. 16.69), and the NDI (29.77 vs. 9.31) scores were much improved. @*Conclusion@#C-TDR is good surgical option. However, it is very important to adhere to strict surgical indications and contraindications to avoid failure of C-TDR. The results of reoperations were good regardless of the approach. Therefore, various reoperation options could be considered in patients with failed C-TDR.

Surgical Strategy for Sacral Tumor Resection

Purpose@#This study aimed to present our experiences with a precise surgical strategy for sacrectomy. @*Materials and Methods@#This study comprised a retrospective review of 16 patients (6 males and 10 females) who underwent sacrectomy from 2011 to 2019. The average age was 42.4 years old, and the mean follow-up period was 40.8 months. Clinical data, including age, sex, history, pathology, radiographs, surgical approaches, onset of recurrence, and prognosis, were analyzed. @*Results@#The main preoperative symptom was non-specific local pain. Nine patients (56%) complained of bladder and bowel symptoms. All patients required spinopelvic reconstruction after sacrectomy. Three patients, one high, one middle, and one hemisacrectomy, underwent spinopelvic reconstruction. The pathology findings of tumors varied (chordoma, n=7; nerve sheath tumor, n=4; giant cell tumor, n=3, etc.). Adjuvant radiotherapy was performed for 5 patients, chemotherapy for three, and combined chemoradiotherapy for another three. Six patients (38%) reported postoperative motor weakness, and newly postoperative bladder and bowel symptoms occurred in 5 patients. Three patients (12%) experienced recurrence and expired. @*Conclusion@#In surgical resection of sacral tumors, the surgical approach depends on the size, location, extension, and pathology of the tumors. The recommended treatment option for sacral tumors is to remove as much of the tumor as possible. The level of root sacrifice is a predicting factor for postoperative neurologic functional impairment and the potential for morbidity. Pre-operative angiography and embolization are recommended to prevent excessive bleeding during surgery. Spinopelvic reconstruction must be considered following a total or high sacrectomy or sacroiliac joint removal.

Sacral Reconstruction with a 3D-Printed Implant after Hemisacrectomy in a Patient with Sacral Osteosarcoma: 1-Year Follow-Up Result

Pelvic reconstruction after sacral resection is challenging in terms of anatomical complexity, excessive loadbearing, and wide defects. Nevertheless, the technological development of 3D-printed implants enables us to overcome these difficulties. Here, we present a case of sacral osteosarcoma surgically treated with hemisacrectomy and sacral reconstruction using a 3D-printed implant. The implant was printed as a customized titanium prosthesis from a 3D real-sized reconstruction of a patient's CT images. It consisted mostly of a porous mesh and incorporated a dense strut. After 3-months of neoadjuvant chemotherapy, the patient underwent hemisacretomy with preservation of contralateral sacral nerves. The implant was anatomically installed on the defect and fixed with a screw-rod system up to the level of L3. Postoperative pain was significantly low and the patient recovered sufficiently to walk as early as 2 weeks postoperatively. The patient showed left-side foot drop only, without loss of sphincter function. In 1-year follow-up CT, excellent bony fusion was noticed. To our knowledge, this is the first report of a case of hemisacral reconstruction using a custom-made 3D-printed implant. We believe that this technique can be applied to spinal reconstructions after a partial or complete spondylectomy in a wide variety of spinal diseases.

Inter- and Intra-Observer Variability of the Volume of Cervical Ossification of the Posterior Longitudinal Ligament Using Medical Image Processing Software

OBJECTIVE: Computed tomography (CT)-based method of three dimensional (3D) analysis (MIMICS®, Materialise, Leuven, Belgium) is reported as very useful software for evaluation of OPLL, but its reliability and reproducibility are obscure. This study was conducted to evaluate the accuracy of MIMICS® system, and inter- and intra-observer reliability in the measurement of OPLL. METHODS: Three neurosurgeons independently analyzed the randomly selected 10 OPLL cases with medical image processing software (MIMICS®) which create 3D model with Digital Imaging and Communication in Medicine (DICOM) data from CT images after brief explanation was given to examiners before the image construction steps. To assess the reliability of inter- and intra-examiner intraclass correlation coefficient (ICC), 3 examiners measured 4 parameters (volume, length, width, and length) in 10 cases 2 times with 1-week interval. RESULTS: The inter-examiner ICCs among 3 examiners were 0.996 (95% confidence interval [CI], 0.987–0.999) for volume measurement, 0.973 (95% CI, 0.907–0.978) for thickness, 0.969 (95% CI, 0.895–0.993) for width, and 0.995 (95% CI, 0.983–0.999) for length. The intra-examiner ICCs were 0.994 (range, 0.991–0.996) for volume, 0.996 (range, 0.944–0.998) for length, 0.930 (range, 0.873–0.947) for width, and 0.987 (range, 0.985–0.995) for length. CONCLUSION: The medical image processing software (MIMICS®) provided detailed quantification OPLL volume with minimal error of inter- and intra-observer reliability in the measurement of OPLL.

Matched Comparison of Fusion Rates between Hydroxyapatite Demineralized Bone Matrix and Autograft in Lumbar Interbody Fusion

OBJECTIVE: To compare the fusion rate of a hydroxyapatite demineralized bone matrix (DBM) with post-laminectomy acquired autograft in lumbar interbody fusion surgery and to evaluate the correlation between fusion rate and clinical outcome. METHODS: From January 2013 to April 2014, 98 patients underwent lumbar interbody fusion surgery with hydroxyapatite DBM (HA-DBM group) in our institute. Of those patients, 65 received complete CT scans for 12 months postoperatively in order to evaluate fusion status. For comparison with autograft, we selected another 65 patients who underwent lumbar interbody fusion surgery with post-laminectomy acquired autograft (Autograft group) during the same period. Both fusion material groups were matched in terms of age, sex, body mass index (BMI), and bone mineral density (BMD). To evaluate the clinical outcomes, we analyzed the results of visual analogue scale (VAS), Oswestry Disability Index (ODI), and Short Form Health Survey (SF-36). RESULTS: We reviewed the CT scans of 149 fusion levels in 130 patients (HA-DBM group, 75 levels/65 patients; Autograft group, 74 levels/65 patients). Age, sex, BMI, and BMD were not significantly different between the groups (p=0.528, p=0.848, p=0.527, and p=0.610, respectively). The HA-DBM group showed 39 of 75 fused levels (52%), and the Autograft group showed 46 of 74 fused levels (62.2%). This difference was not statistically significant (p=0.21). In the HA-DBM group, older age and low BMD were significantly associated with non-fusion (61.24 vs. 66.68, p=0.027; -1.63 vs. -2.29, p=0.015, respectively). VAS and ODI showed significant improvement after surgery when fusion was successfully achieved in both groups (p=0.004, p=0.002, HA-DBM group; p=0.012, p=0.03, Autograft group). CONCLUSION: The fusion rates of the hydroxyapatite DBM and Autograft groups were not significantly different. In addition, clinical outcomes were similar between the groups. However, older age and low BMD are risk factors that might induce non-union after surgery with hydroxyapatite DBM.

Compression Angle of Ossification of the Posterior Longitudinal Ligament and Its Clinical Significance in Cervical Myelopathy

OBJECTIVES: The correction of clinical and radiologic abnormalities in patients with symptomatic ossification of the posterior longitudinal ligament (OPLL) is the current mainstay of treatment. This study aimed to identify radiographic predictors of severity of myelopathy in patients with symptomatic OPLL. METHODS: Fifty patients with symptomatic cervical OPLL were enrolled. Based on Japanese Orthopedic Association (JOA) scores, patients were divided into either the mild myelopathy (n=31) or severe myelopathy (n=19) group. All subjects underwent preoperative plain cervical roentgenogram, computed tomography (CT), and MR imaging (MRI). Radiological parameters (C2–7 sagittal vertical axis, SVA; C2–7 Cobb angle; C2–7 range of motion, ROM; OPLL occupying ratio; and compression angle) were compared. Compression angle of OPLL was defined as the angle between the cranial and caudal surfaces of OPLL at the maximum level of cord compression RESULTS: The occupying ratio of the spinal canal, C2–7 Cobb angle, C2–7 SVA, types of OPLL, and C2–7 ROM of the cervical spine were not statistically different between the two groups. However, the OPLL compression angle was significantly greater (p=0.003) in the severe myelopathy group than in the mild myelopathy group and was inversely correlated with JOA score (r=-0.533, p<0.01). Furthermore, multivariate regression analysis demonstrated that the compression angle (B=-0.069, p<0.001) was significantly associated with JOA scores (R=0.647, p<0.005). CONCLUSION: Higher compression angles of OPLL have deleterious effects on the spinal cord and decrease preoperative JOA scores.

Efficacy and Safety of Sodium Hyaluronate with 1,4-Butanediol Diglycidyl Ether Compared to Sodium Carboxymethylcellulose in Preventing Adhesion Formation after Lumbar Discectomy

OBJECTIVE: Epidural injection of hyaluronic acid may prevent adhesion formation after spine surgery, but the compounds used to stabilize hyaluronidase could interfere with its anti-adhesion effects. The present study was conducted as a clinical trial to evaluate the efficacy and safety of an experimental medical gel in preventing adhesion formation. METHODS: This study was designed as a multicenter, randomized, double-blind, and comparative controlled clinical trial with an observation period of 6 weeks. Subjects were randomly assigned into two groups: group A with sodium hyaluronate + 1,4-butanediol diglycidyl ether (BDDE) and group B with sodium hyaluronate + sodium carboxymethylcellulose (CMC). Visual analogue scale (VAS) of back and leg pain and the Oswestry disability index (ODI) and scar score ratings were assessed after surgery. RESULTS: Mean scar grade was 2.37+/-1.13 in group A and 2.75+/-0.97 in group B, a statistically significant difference (p=0.012). VAS of back and leg pain and ODI scores decreased significantly from baseline to 3 and 6 weeks postoperatively in both groups (p0.3). The number of adverse reactions related to the anti-adhesion gels was not statistically different (p=0.569), but subsequent analysis of nervous adverse reactions showed group B was superior with a statistically difference (p=0.027). CONCLUSION: Sodium hyaluronate with BDDE demonstrated similar anti-adhesion properties to sodium hyaluronate with CMC. But, care should be used to nervous adverse reactions by using sodium hyaluronate with BDDE.

Feasibility of Translaminar Screw Placement in Korean Population: Morphometric Analysis of Cervical Spine

PURPOSE: To analyze the feasibility of unilateral and bilateral translaminar screw placement in Koran population, and compare the acceptance rate using previously reported data in American population. MATERIALS AND METHODS: The translaminar lengths, thickness, heights, and sagittal-diagonal measurements were performed. The feasibility analysis was performed using unilateral and bilateral 3.5 mm cervical screw placement on the CT scans within 0.5 mm of safety margin. We also performed radiographic analysis of the morphometric dimensions and the feasibility of unilateral and bilateral translaminar screw placement at C3-C7. RESULTS: Korean population had similar or significantly shorter translaminar lengths and thickness (lengths and thickness in C7 among males; lengths in C6-C7 and thickness in C4 among females) than American population, but had similar or significantly longer translaminar heights and sagittal-diagonal measurements (heights in C3-C7 and sagittal-diagonal measurements in C3-C6 among males; heights in C7 and sagittal-diagonal measurements in C3-C7 among females). Unilaterally, translaminar screw acceptance rates in C3-C7 were similar between Korean and American male population, but the rates in C4-C6 were significantly smaller between Korean and American female population. Bilaterally, translaminar screw acceptance rates in C3 and C5-C6 were significantly larger between Korean and American male population, but the rates in C3-C7 were similar between Korean and American female population. CONCLUSION: The feasibility of unilateral and bilateral translaminar screw placement is different depending on different ethnics. Subaxial cervical unilateral translaminar screw placement among Korean male population and bilateral placement at C4-C7 among Korean female population are more acceptable than American population.

Biologic Response of Degenerative Living Human Nucleus Pulposus Cells to Treatment with Cytokines

PURPOSE: To investigate the molecular responses of various genes and proteins related to disc degeneration upon treatment with cytokines that affect disc-cell proliferation and phenotype in living human intervertebral discs (IVDs). Responsiveness to these cytokines according to the degree of disc degeneration was also evaluated. MATERIALS AND METHODS: The disc specimens were classified into two groups: group 1 (6 patients) showed mild degeneration of IVDs and group 2 (6 patients) exhibited severe degeneration of IVDs. Gene expression was analyzed after treatment with four cytokines: recombinant human bone morphogenic protein (rhBMP-2), transforming growth factor-beta (TGF-beta), interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNF-alpha). Molecular responses were assessed after exposure of cells from the IVD specimens to these cytokines via real-time polymerase chain reaction and immunofluorescence staining. RESULTS: mRNA gene expression was significantly greater for aggrecan, type I collagen, type II collagen, alkaline phosphatase, osteocalcin, and Sox9 in group 1 than mRNA gene expression in group 2, when the samples were not treated with cytokines. Analysis of mRNA levels for these molecules after morphogen treatment revealed significant increases in both groups, which were much higher in group 1 than in group 2. The average number of IVD cells that were immunofluorescence stained positive for alkaline phosphatase increased after treatment with rhBMP-2 and TGF-beta in group 1. CONCLUSION: The biologic responsiveness to treatment of rhBMP-2, TGF-beta, TNF-alpha, and IL-1beta in the degenerative living human IVD can be different according to the degree of degeneration of the IVD.

The Use of Magnetic Resonance Imaging in Predicting the Clinical Outcome of Spinal Arteriovenous Fistula

PURPOSE: Magnetic resonance imaging (MRI) has been used to screen and follow-up spinal dural arteriovenous fistulae (SDAVF). The purpose of this study was to evaluate the association between MRI findings and neurologic function in SDAVF. This study also investigated clinical features and treatment results of SDAVF. MATERIALS AND METHODS: A total of 15 consecutive patients who underwent embolization or surgery for SDAVF were included. We treated seven (60%) patients with embolization and six (40%) with surgery. We analysed clinical features, MRI findings, treatment results, and neurologic function. Neurologic function was measured by the Aminoff-Logue disability scale (ALS). RESULTS: Patients with longer levels of intramedullary high signal intensity in preoperative T2-weighted images (T2WI) exhibited worse pre- and postoperative ALS scores (r=0.557, p=0.031; r=0.530, p=0.042, Pearson correlation). Preoperative ALS score was significantly correlated with postoperative ALS score (r=0.908, p=0.000, Pearson correlation). The number of levels showing intramedullary high signal intensity in T2WI decreased significantly postoperatively (5.2+/-3.1 vs. 1.0+/-1.4, p=0.001, Wilcoxon ranked test). CONCLUSION: The number of involved levels of high signal intensity in preoperative T2WI is useful for predicting pre- and postoperative neurologic function in SDAVF.

The Use of Magnetic Resonance Imaging in Predicting the Clinical Outcome of Spinal Arteriovenous Fistula

PURPOSE: Magnetic resonance imaging (MRI) has been used to screen and follow-up spinal dural arteriovenous fistulae (SDAVF). The purpose of this study was to evaluate the association between MRI findings and neurologic function in SDAVF. This study also investigated clinical features and treatment results of SDAVF. MATERIALS AND METHODS: A total of 15 consecutive patients who underwent embolization or surgery for SDAVF were included. We treated seven (60%) patients with embolization and six (40%) with surgery. We analysed clinical features, MRI findings, treatment results, and neurologic function. Neurologic function was measured by the Aminoff-Logue disability scale (ALS). RESULTS: Patients with longer levels of intramedullary high signal intensity in preoperative T2-weighted images (T2WI) exhibited worse pre- and postoperative ALS scores (r=0.557, p=0.031; r=0.530, p=0.042, Pearson correlation). Preoperative ALS score was significantly correlated with postoperative ALS score (r=0.908, p=0.000, Pearson correlation). The number of levels showing intramedullary high signal intensity in T2WI decreased significantly postoperatively (5.2+/-3.1 vs. 1.0+/-1.4, p=0.001, Wilcoxon ranked test). CONCLUSION: The number of involved levels of high signal intensity in preoperative T2WI is useful for predicting pre- and postoperative neurologic function in SDAVF.

Efficacy of Percutaneous Epidural Neuroplasty Does Not Correlate with Dural Sac Cross-Sectional Area in Single Level Disc Disease

PURPOSE: Percutaneous epidural neuroplasty (PEN) is a minimally invasive treatment. The efficacy of PEN has been relatively well investigated; however, the relationship between the clinical effectiveness of PEN and the severity of spinal canal stenosis by disc material has not yet been established. The purpose of this study was to compare clinical outcomes of PEN according to the dural sac cross-sectional area in single level disc disease. MATERIALS AND METHODS: This study included 363 patients with back pain from single level disc disease with and without radiculopathy. Patients were categorized into groups according to spinal canal compromise by disc material: Category 1, less or more than 50%; and Category 2, three subgroups with lesser than a third, between a third and two thirds, and more than two thirds. Clinical outcomes were assessed according to the Visual Analog Scale (VAS) score for back pain and leg pain and Odom's criteria at 1, 3, 6, 12, and 24 months after treatment. RESULTS: The demographic data showed no difference between groups according to spinal canal compromise by disc material except age (older age correlated with more spinal canal compromise). The dural sac cross-sectional area did not correlate with the VAS scores for back and leg pain after PEN in single level disc disease in Groups 1 and 2. Odom's criteria after PEN were also not different according to dural sac cross-sectional area by disc material. CONCLUSION: PEN is an effective procedure in treating single level lumbar disc herniation without affecting dural sac cross-sectional area.

Three Cases of Spine Fractures after an Airplane Crash / 대한신경손상학회지

While injuries to the spine after an airplane crash are not rare, most crashes result in fatal injuries. As such, few studies exist that reported on spine fractures sustained during airplane accidents. In this report, we demonstrate three cases of spine fractures due to crash landing of a commercial airplane. Three passengers perished from injuries after the crash landing, yet most of the passengers and crew on board survived, with injuries ranging from minor to severe. Through evaluating our three spine fracture patients, it was determined that compression fracture of the spine was the primary injury related to the airplane accident. The first patient was a 20-year-old female who sustained a T6-8 compression fracture without neurologic deterioration. The second patient was a 33-year-old female with an L2 compression fracture, and the last patient was a 49-year-old male patient with a T8 compression fracture. All three patients were managed conservatively and required spinal orthotics. During the crash, each of these patients were subjected to direct, downward high gravity z-axis (Gz) force, which gave rise to load on the spine vertically, thereby causing compression fracture. Therefore, new safety methods should be developed to prevent excessive Gz force during airplane crash landings.

Delayed Bilateral C5 Palsy following Circumferential Decompression and Fusion in Patient with Cervical Spondylotic Myelopathy

C5 palsy is a common complication after cervical decompressive surgery, which have 0 to 30% complication rate. A 61-year-old female patient with cervical spondylotic myelopathy showed bilateral C5 palsy following circumferential decompression and fusion. Unexpectedly, bilateral C5 palsy was noted in different time points on postoperative day 2 and 8, respectively. Steroid injection and physical therapy were performed, and her motor function is recovering. Surgeons should make an effort to prevent possible C5 palsy when performing cervical decompression surgery.

Surgical Outcomes after Traumatic Vertebral Fractures in Patients with Ankylosing Spondylitis

OBJECTIVE: Ankylosing spondylitis is an inflammatory rheumatic disease mainly affecting the axial skeleton. The rigid spine may secondarily develop osteoporosis, further increasing the risk of spinal fracture. In this study, we reviewed fractures in patients with ankylosing spondylitis that had been clinically diagnosed to better define the mechanism of injury, associated neurological deficit, predisposing factors, and management strategies. METHODS: Between January 2003 and December 2013, 12 patients with 13 fractures with neurological complications were treated. Neuroimaging evaluation was obtained in all patients by using plain radiography, CT scan, and MR imaging. The ASIA Impairment Scale was used in order to evaluate the neurologic status of the patients. Management was based on the presence or absence of spinal instability. RESULTS: A total of 9 cervical and 4 thoracolumbar fractures were identified in a review of patients in whom ankylosing spondylitis had been diagnosed. Of these, 7 fractures were associated with a hyperextension mechanism. 10 cases resulted in a fracture by minor trauma. Posttraumatic neurological deficits were demonstrated in 11 cases and neurological improvement after surgery was observed in 5 of these cases. CONCLUSIONS: Patients with ankylosing spondylitis are highly susceptible to spinal fracture and spinal cord injury even after only mild trauma. Initial CT or MR imaging of the whole spine is recommended even if the patient's symptoms are mild. The patient should also have early surgical stabilization to correct spinal deformity and avoid worsening of the patient's neurological status.

Rosai-Dorfman Disease in Thoracic Spine: A Rare Case of Compression Fracture

Sinus histiocytosis with massive lymphadenopathy known as Rosai-Dorfman disease is characterized by painless bilateral cervical lymphadenopathy. Extranodal manifestations are uncommon and spinal involvement is rare. A 15-year-old man presented with intermittent midthoracic back pain only. He had no specific findings on neurologic examinations, hematologic and biochemical laboratory tests. Radiological examination of thoracic spine revealed collapse of T6 vertebrae with thoracic kyphosis and osteolytic lesion of T12 vertebra body. He underwent a removal of bone tumor, anterior reconstruction with mesh and pedicle screw fixation via posterior approach for pathologic confirmation and stabilization. Histopathologic study of the lesion revealed focal infiltration of large histiocytes showing emperipolesis. Immunochemistry stain of histiocytes was positive for CD68 and S-100 but negative for CD1a. This report presents a rare case and literature review of extranodal Rosai-dorfman disease in thoracic spine.