Publications by authors named "Seung Chul Rhim"

75 Publications

Intraoperative Monitoring for Cauda Equina Tumors: Surgical Outcomes and Neurophysiological Data Accrued Over 10 Years.

Neurospine 2021 Jun 30;18(2):281-289. Epub 2021 Jun 30.

Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Objective: Cauda equina tumors affect the peripheral nervous system, and the validities of triggered electromyogram (tEMG) and intraoperative neurophysiologic monitoring (IOM) are unclear. We sought to evaluate the accuracy and relevance of tEMG combined with IOM during cauda equina tumor resection.

Methods: Between 2008 and 2018, an experienced surgeon performed cauda equina tumor resections using tEMG at a single institution. A cauda equina tumor was defined as an intradural-extramedullary or intradural-extradural tumor at the level of L2 or lower. The clinical presentation, extent of resection, pathology, recurrence, postoperative neurological outcomes, and intraoperative tEMG mapping and IOM data were retrospectively analyzed.

Results: One hundred three patients who underwent intraoperative tEMG were included; 38 underwent only tEMG (tEMG-only group), and 65 underwent a combination of tEMG and multimodal IOM (MIOM group). There were no significant differences between the neurologic outcomes, extents of resection, or recurrence rates of the 2 groups. No significant therapeutic benefit was observed; however, the accuracy of intraoperative predetection improved with the combination of IOM and tEMG (accuracy: tEMG-only group, 86.8%; MIOM group, 92.3%). When the involved rootlet was resected despite the positive tEMG result, motor function worsened in 3 of 8 cases. The sensitivity and specificity of tEMG were 37.5% and 94.7%, respectively.

Conclusion: tEMG is an essential adjunctive surgical tool for deciding on and planning for rootlet resection. If the tEMG finding is negative, complete resection, involving the rootlet, may be safe. The accuracy may be further improved by using a combination of tEMG and IOM.
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http://dx.doi.org/10.14245/ns.2040660.330DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8255760PMC
June 2021

Posterior Cervical Muscle-Preserving Interspinous Process Approach and Decompression: More Minimally Invasive and Modified Shiraishi's Selective Laminectomy.

World Neurosurg 2020 Jan 16;133:e412-e420. Epub 2019 Sep 16.

Department of Emergency Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung-si, Republic of Korea.

Objective: The cervical extensor musculature is important in cases of neck pain and loss of cervical lordosis after laminoplasty. Therefore, various surgical methods have been developed to preserve the muscle during laminoplasty. We have developed a posterior cervical muscle-preserving interspinous process (MIS) approach and decompression method. We have described the operation details and clinical outcomes of selected patients who have undergone this procedure.

Methods: The MIS approach and decompression method were performed in 20 consecutive patients who had only required central decompression for cervical stenosis. This procedure includes an approach to the interspinous space that is similar to Shiraishi's method but includes decompression without fracturing the spina bifida.

Results: The patients had no complications and did not require conversion to conventional laminoplasty. The mean operative time and mean blood loss was 53.0 minutes and 63.0 mL per level, respectively, and the mean hospital stay was 4.0 days. The mean preoperative and 3-month postoperative modified Japanese Orthopedic Association scores were 12.6 and 16.2, and the mean preoperative and 3-month postoperative neck disability index scores were 15.4 and 2.5, respectively. The postoperative neck visual analog scale score was 0.8. The mean preoperative and postoperative sagittal vertical axis was 1.6 and 1.8 cm, respectively. The mean loss of lordosis was 1.0°, and the mean cervical range of motion did not change from preoperatively to postoperatively.

Conclusions: The MIS approach and decompression method was less invasive than both conventional laminoplasty and Shiraishi's selective laminectomy. It is a safe and effective minimally invasive technique for central stenosis caused by cervical spondylotic myelopathy.
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http://dx.doi.org/10.1016/j.wneu.2019.09.041DOI Listing
January 2020

The Learning Curve of Subaxial Cervical Pedicle Screw Placement: How Can We Avoid Neurovascular Complications in the Initial Period?

Oper Neurosurg (Hagerstown) 2019 12;17(6):603-607

Department of Neurosurgery, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Republic of Korea.

Background: Despite the biomechanical benefits of subaxial cervical pedicle screw (CPS) placement, possible neurovascular complications, including vertebral artery and nerve root injury, are of great concern. We have demonstrated many times the safety and efficacy of CPS deployments, even when using freehand technology.

Objective: To analyze the learning curve of CPS placement to determine the number of cases necessary for assuring safe CPS placement and to identify a reasonable accuracy rate.

Methods: From March 2012 to August 2018, a single surgeon performed posterior cervical fusion surgery using CPS placement on 162 consecutive patients. We classified whole surgical periods, 6 years, into 4 periods. We analyzed the screw breach rate, lateral mass screw conversion (LMSC) rate, and reposition rate. We also compared the CPS placement accuracy in the initial 15, 20, and 30 patients with the other 147, 142, and 132 patients, respectively, to assess the number of procedures necessary to reach the learning curve plateau and to identify a reasonable accuracy rate.

Result: The total number of planned CPS placements was 979. Our learning curve showed that the breach rate plateaus at 3% to 4%. The necessary numbers for safe and accurate CPS placement during learning curve were 30 patients and 170 screws. None of the patients undergoing CPS developed a neurologic or vascular complication.

Conclusion: By following our 5 safety steps, the steady state for safety and accuracy can be reached without neurovascular complications even in the initial period of the learning curve.
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http://dx.doi.org/10.1093/ons/opz070DOI Listing
December 2019

Anterior Odontoid Screw Fixation for the Treatment of Type 2 Odontoid Fracture with a Kyphotic Angulation or an Anterior Down-slope: A Technical Note.

Neurol Med Chir (Tokyo) 2019 Aug 9;59(8):321-325. Epub 2019 May 9.

Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine.

Anterior odontoid screw fixation (AOSF) is difficult and challenging to perform in patients with type 2 odontoid fracture with a kyphotic angulation or an anterior down-slope. To demonstrate two surgical techniques to resolve kyphotic angulation or difficult fracture direction issues. Anterior odontoid screw fixation was performed in two patients with type 2 odontoid fracture with a kyphotic angulation or an anterior down-slope. This technique can avoid sternal blocking using a percutaneous vertebroplasty puncture needle, and can reduce the kyphotic angle using a Cobb elevator in patients with type 2 odontoid fractures with a kyphotic angulation or an anterior down-sloped fracture. In both the patients, AOSF was successfully performed and a successful clinical outcome was achieved. The screws were well-maintained with reduced fracture segment and well-preserved, corrected kyphotic angles were achieved, as observed on cervical X-ray 6 months postoperatively. Our technique is a safe and effective method for the treatment of type 2 odontoid fracture with a kyphotic angulation or an anterior down-slope.
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http://dx.doi.org/10.2176/nmc.tn.2018-0249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6694020PMC
August 2019

Surgical Treatment of Lumbar Spinal Discal Cyst: Is It Enough to Remove the Cyst Only without Following Discectomy?

Neurol Med Chir (Tokyo) 2019 Jun 9;59(6):204-212. Epub 2019 May 9.

Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine.

Discal cysts are a rare cause of low back pain and radiculopathy with unknown pathophysiologic mechanism. Associated symptoms are difficult to distinguish from those caused by extruded discs and other spinal canal lesions. Most discal cysts are treated surgically, but it is unclear whether the corresponding intervertebral disc should be excised along with cyst. We conducted a retrospective clinical review of 27 patients who underwent discal cyst excision at our institution between 2000 and 2017. The mean follow-up period was 63.6 months. We recorded symptoms, radiographs, operative findings, postoperative complications, and short- and long-term outcomes. Structured outcome assessment was based on Numeric Rating Scale (NRS) for pain intensity, Oswestry disability index, and Macnab classification. All patients underwent partial hemilaminectomy and microscopic cyst resection without discectomy. All patients had preoperative back or leg pain. Other preoperative clinical features included motor weakness, neurogenic intermittent claudication, and cauda equina syndrome. After surgery, NRS scores of back and leg pain decreased. The other symptoms also improved. During long-term follow-up, patients reported no restrictions on daily life activities, and were satisfied with our intervention. There were no cases of cyst recurrence. We conducted a review of the literature on lumbar discal cysts published before January, 2018. Including our cases, 126 patients were described. We compared two surgical modalities-cystectomy with and without discectomy-to elucidate both effectiveness and long-term complications. We found that microsurgical cystectomy without corresponding discectomy is an effective surgical treatment for lumbar discal cysts, and is associated with a low recurrence rate.
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http://dx.doi.org/10.2176/nmc.oa.2018-0219DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6580042PMC
June 2019

Effect of Vertebroplasty at the Upper Instrumented Vertebra and Upper Instrumented Vertebra +1 for Prevention of Proximal Junctional Failure in Adult Spinal Deformity Surgery: A Comparative Matched-Cohort Study.

World Neurosurg 2019 Jan 3. Epub 2019 Jan 3.

Department of Neurosurgery, Hallym University Hangang Sacred Heart Hospital, Seoul, Korea.

Background: This study aimed to compare radiographic outcomes of adult spinal deformity (ASD) surgery with or without 2-level prophylactic vertebroplasty (PVP) at the uppermost instrumented vertebra (UIV) and the vertebra 1 level proximal to the UIV.

Methods: This retrospective 1:2 matched-cohort comparative study enrolled 2 groups of patients undergoing ASD surgery, including 28 patients with PVP (PVP group) and 56 patients without PVP (non-PVP group), in 3 institutes between 2012 and 2015. The primary outcome measure was the incidence of proximal junctional kyphosis (PJK), proximal junctional failure (PJF), and proximal junctional fracture (PJFX). The secondary outcome measure were radiologic outcomes between PVP segments and non-PVP segments.

Results: Between the PVP group and non-PVP group, no significant differences were found in the incidence of PJK (13 [46.4%] vs. 26 [46.4%]; P = 1.000), PJF (11 [39.3%] vs. 18 [32.1%]; P = 0.516), and PJFX (11 [39.3%] vs. 18 [32.1%]; P = 0.516). The number of the PJFX segments was 16 and 33 in PVP segments and non-PVP segments, respectively. Until revision surgery or final follow-up, the PJFX had progressed in 24 non-PVP segments (82.7%), but not in PVP segments. The PJFX progression in all PVP segments stopped near the PVP mass at the final follow-up. Reoperation as a result of PJFX was performed in 1 patient (3.6%) and 8 patients (14.3%) in the PVP and non-PVP groups, respectively.

Conclusions: PVP at UIV and vertebra 1 level proximal to the UIV cannot prevent PJK, PJF, and PJFX; however, it plays a positive role by delaying their progression. Furthermore, PVP tends to lower the reoperation rate after PJFX in ASD surgery.
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http://dx.doi.org/10.1016/j.wneu.2018.12.113DOI Listing
January 2019

The time course of cervical alignment after cervical expansive laminoplasty: Determining optimal cut-off preoperative angle for predicting postoperative kyphosis.

Medicine (Baltimore) 2018 Nov;97(47):e13335

Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Retrospective Cohort studyTo analyze cervical lordosis angle (CLA) change after cervical expansive laminoplasty (CEL) over time, and to determine optimal cut-off angle for predicting postoperative kyphosisPostoperative development of sagittal malalignment after laminoplasty is associated with neurological dysfunction and neck pain. However, there is no information on the serial CLA change over time and cut-off angle for predicting postoperative kyphosisThe Cobb angle between C2 and C7 in a series of lateral cervical X-rays in the neutral position was retrospectively reviewed for 36 months. And, the effect of time on CLA after CEL and the risk factors associated with postoperative cervical kyphosis (Cobb's angle ≤0°) were analyzed. Also, the optimal cut-off angle for predicting postoperative kyphosis was determined.A total of 110 cases of CEL for cervical myelopathy were enrolled from February 2005 to May 2010. The mean cervical alignment changed from 12.3 ± 10.4° (mean ± standard deviation [SD]) at the preoperative evaluation to 8.2 ± 11.6°, 10.6 ± 10.1°, 9.1 ± 10.0°, 8.4 ± 11.2°, 8.5 ± 10.5°, 8.1 ± 9.9°, and 8.7 ± 10.1° at 1, 3, 6, 12, 18, 24, and 36 postoperative months, respectively. The cervical lordosis showed statistically significant decreased at the 1st month, then the lordotic angle was partially restored at the 3rd, and 6th, and then no significant changes after the 6th. The only risk factor for kyphosis development was the preoperative CLA. The optimal cut-off preoperative angle for predicting postoperative kyphosis was 8.5°.The decrease of CLA after expansive laminoplasty peaked in the 1st month. Some of the lordotic angles were restored in the 3rd and 6th months, before reaching a plateau after the 6th month. The optimal cut-off preoperative angle for predicting postoperative kyphosis was 8.5°.Level of Evidence of their study: Level 4.
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http://dx.doi.org/10.1097/MD.0000000000013335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6393087PMC
November 2018

Clinically significant radiographic parameter for thoracic myelopathy caused by ossification of the ligamentum flavum.

Eur Spine J 2019 08 6;28(8):1846-1854. Epub 2018 Sep 6.

Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro43-gil, Songpa-gu, Seoul, 05505, South Korea.

Purpose: To investigate radiographic parameters to improve the accuracy of radiologic diagnosis for ossification of ligamentum flavum (OLF)-induced thoracic myelopathy and thereby establish a useful diagnostic method for identifying the responsible segment.

Methods: We classified 101 patients who underwent surgical treatment for OLF-induced thoracic myelopathy as the myelopathy group and 102 patients who had incidental OLF and were hospitalized with compression fracture as the non-myelopathy group between January 2009 and December 2016. We measured the thickness of OLF (TOLF), cross-sectional area of OLF (AOLF), anteroposterior canal diameter, and the ratio of each of these parameters.

Results: Most OLF cases with lateral-type axial morphology were in the non-myelopathy group and most with fused and tuberous type in the myelopathy group. Most grade-I and grade-II cases were also in the non-myelopathy group, whereas grade-IV cases were mostly observed in the myelopathy group. The AOLF ratio was found to be the best radiologic parameter. The optimal cutoff point of the AOLF ratio was 33.00%, with 87.1% sensitivity and 87.3% specificity. The AOLF ratio was significantly correlated with preoperative neurological status.

Conclusions: An AOLF ratio greater than 33% is the most accurate diagnostic indicator of OLF-induced thoracic myelopathy. In cases of multiple-segment OLF, confirmation of cord signal change on MRI and an AOLF measurement will help determine the responsible segment. AOLF measurement will also improve the accuracy of diagnosis of OLF-induced thoracic myelopathy in cases of grade III or extended-type axial morphology. These slides can be retrieved under Electronic Supplementary Material.
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http://dx.doi.org/10.1007/s00586-018-5750-6DOI Listing
August 2019

Importance of the preoperative cross-sectional area of the semispinalis cervicis as a risk factor for loss of lordosis after laminoplasty in patients with cervical spondylotic myelopathy.

Eur Spine J 2018 11 13;27(11):2720-2728. Epub 2018 Aug 13.

Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43 gil, Songpa-gu, Seoul, 05505, Korea.

Purpose: To investigate the effect of the preoperative cross-sectional area (CSA) of the semispinalis cervicis on postoperative loss of cervical lordosis (LCL) after laminoplasty.

Methods: A total of 144 patients who met the inclusion criteria between January 1999 and December 2015 were enrolled. Radiographic assessments were performed to evaluate the T1 slope, C2-7 sagittal vertical axis (SVA), cephalad vertebral level undergoing laminoplasty (CVLL), preoperative C2-7 Cobb angle, and preoperative CSA of the semispinalis cervicis.

Results: The T1 slope and the summation of the CSAs (SCSA) at each level of the semispinalis cervicis correlated with LCL, whereas the C2-7 SVA, CVLL, and preoperative C2-7 Cobb angle did not. Multiple regression analysis demonstrated that a high T1 slope and a low SCSA of the semispinalis cervicis were associated with LCL after laminoplasty in patients with cervical spondylotic myelopathy (CSM). The CSA of the semispinalis cervicis at the C6 level had the greatest association with LCL, which suddenly decreased with a LCL of 10°. The best cutoff point of the CSA of the semispinalis cervicis at the C6 level, which predicts LCL > 10°, was 154.5 mm (sensitivity 74.3%; specificity 71.6%; area under the curve 0.828; 95% confidence interval 0.761-0.895).

Conclusion: Preoperative SCSA of the semispinalis cervicis was a risk factor for LCL after laminoplasty. Spine surgeons should evaluate semispinalis cervicis muscularity at the C6 level when planning laminoplasty for patients with CSM. These slides can be retrieved under Electronic Supplementary Material.
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http://dx.doi.org/10.1007/s00586-018-5726-6DOI Listing
November 2018

Analysis of the Risk Factors Associated with Prolonged Intubation or Reintubation after Anterior Cervical Spine Surgery.

J Korean Med Sci 2018 Apr 30;33(17):e77. Epub 2018 Jan 30.

Department of Neurological Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Background: Standardized postoperative airway management is essential for patients undergoing anterior cervical spine surgery (ACSS). The paucity of clinical series evaluating these airway complications after ACSS has been resulted in a significant limitation in statistical analyses.

Methods: A retrospective cohort study was performed regarding airway distress (intubation for more than 24 hours or unplanned reintubation within 7 days of operation) developed after ACSS. If prevertebral soft tissue swelling was evident after the operation, patients were managed with prolonged intubation (longer than 24 hours). Preoperative and intraoperative patient data, and postoperative outcome (time to extubation and reintubation) were analyzed.

Results: Between 2008 and 2016, a total of 400 ACSS were performed. Of them, 389 patients (97.25%) extubated within 24 hours of surgery without airway complication, but 11 patients (2.75%) showed postoperative airway compromise; 7 patients (1.75%) needed prolonged intubation, while 4 patients (1.00%) required unplanned reintubation. The mean time for extubation were 2.75 hours (range: 0-23 hours) and 50.55 hours (range: 0-250 hours), respectively. Age ( = 0.015), diabetes mellitus ( = 0.003), operative time longer than 5 hours ( = 0.048), and estimated blood loss (EBL) greater than 300 mL ( = 0.042) were associated with prolonged intubation or reintubation. In prolonged intubation group, all patients showed no airway distress after extubation.

Conclusion: In ACSS, postoperative airway compromise is related to both patients and operative factors. We recommend a prolonged intubation for patients who are exposed to these risk factors to perform a safe and effective extubation.
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http://dx.doi.org/10.3346/jkms.2018.33.e77DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5909108PMC
April 2018

Adolescent Idiopathic Scoliosis Surgery by a Neurosurgeon: Learning Curve for Neurosurgeons.

World Neurosurg 2018 Feb 28;110:e129-e134. Epub 2017 Oct 28.

Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Gyeonggi, Korea.

Objective: To determine a neurosurgeon's learning curve of surgical treatment for adolescent idiopathic scoliosis (AIS) patients.

Methods: This study is a retrospective analysis. Forty-six patients were treated by a single neurosurgeon between 2011 and 2017 using posterior segmental instrumentation and fusion. According to the time period, the former and latter 23 patients were divided into group 1 and group 2, respectively. Patients' demographic data, curve magnitude, number of levels treated, amount of correction achieved, radiographic/clinical outcomes, and complications were compared between the groups.

Results: The majority were females (34 vs. 12) with average ages of 15.0 versus 15.6, respectively. The mean follow-up period was 24.6 months. The average number of fusion levels was similar with 10.3 and 11.5 vertebral bodies in groups 1 and 2, respectively. The average Cobb angle of major curvature was 59.8° and 58.5° in groups 1 and 2, respectively. There observed significant reductions of operative time (324.4 vs. 224.7 minutes, P = 0.007) and estimated blood loss (648.3 vs. 438.0 mL, P = 0.027) in group 2. The correction rate of the major structural curve was greater in group 2 (70.7% vs. 81.0%, P = 0.001). There was no case of neurologic deficit, infection, and revision for screw malposition. One patient of group 1 underwent fusion extension surgery for shoulder asymmetry.

Conclusion: Radiographic and clinical outcomes of AIS patients treated by a neurosurgeon were acceptable. AIS surgery may be performed with an acceptable rate of complications after about 20 surgeries. With acquisition of surgical experiences, neurosurgeons could perform deformity surgery for AIS effectively and safely.
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http://dx.doi.org/10.1016/j.wneu.2017.10.109DOI Listing
February 2018

Long-Term Results Following Surgical Resection of Chordomas in the Craniocervical Junction and the Upper Cervical Spine: Review of 12 Consecutive Cases.

Oper Neurosurg (Hagerstown) 2018 02;14(2):112-120

Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.

Background: Since chordoma is refractory to chemotherapy and conventional radiotherapy, radical surgical resection is mandatory. However, it is surgically demanding in the craniocervical junction (CCJ) and upper cervical spine.

Objective: To analyze long-term surgical results of cervical chordomas.

Methods: We retrospectively reviewed 12 consecutive patients who underwent surgical treatment for CCJ or upper cervical chordomas from 2001 to 2009 in 2 academic institutions. We analyzed the progression-free survival and overall survival and compared the results between gross total resection (GTR) cases and partial resection (PR). Complications were analyzed by comparing primary and recurrent tumor. We also delineated the type of radiotherapy.

Results: Of the 12 patients, 5 underwent GTR and 7 underwent PR. GTR of the tumor was achieved by intralesional piecemeal removal. No recurrence occurred in the GTR group. PR group had 6 cases of regrowth (85.7%). Ten patients (83.3%) underwent any kind of radiation therapy. There were 3 (60%) patients in the GTR group and 7 (100%) in the PR group. Compared to PR, GTR revealed a better 3-yr progression-free survival rate (100% vs 14.3%) as well as a better 3-yr overall survival rate (100% vs 71.4%). Surgical complication rate (40% for GTR vs 42.9% for PR) was not significantly different between the groups. The surgical complication rates of primary and revision surgery were 25% and 75%, respectively. Complication associated with radiation occurred in 2 patients.

Conclusion: Gross total intralesional piecemeal resection with perioperative radiation therapy is an acceptable strategy for CCJ and the upper cervical chordoma management.
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http://dx.doi.org/10.1093/ons/opx082DOI Listing
February 2018

Relevance of Postoperative Magnetic Resonance Images in Evaluating Epidural Hematoma After Thoracic Fixation Surgery.

World Neurosurg 2017 Nov 24;107:803-808. Epub 2017 Aug 24.

Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. Electronic address:

Background: It is difficult to evaluate the significant findings of epidural hematoma in magnetic resonance images (MRIs) obtained immediately after thoracic posterior screw fixation (PSF).

Methods: Prospectively, immediate postoperative MRI was performed in 10 patients who underwent thoracic PSF from April to December 2013. Additionally, we retrospectively analyzed the MRIs from 3 patients before hematoma evacuation out of 260 patients who underwent thoracic PSF from January 2000 to March 2013.

Results: The MRI findings of 9 out of the 10 patients, consecutively collected after thoracic PSF, showed neurologic recovery with a well-preserved cerebrospinal fluid (CSF) space and no prominent hemorrhage. Even though there were metal artifacts at the level of the pedicle screws, the preserved CSF space was observed. In contrast, the MRI of 1 patient with poor neurologic outcome demonstrated a typical hematoma and slight spinal cord compression and reduced CSF space. In the retrospective analysis of the 3 patients who showed definite motor weakness in the lower extremities after their first thoracic fusion surgery and underwent hematoma evacuation, the magnetic resonance images before hematoma evacuation also revealed hematoma compressing the spinal cord and diminished CSF space.

Conclusions: This study shows that epidural hematomas can be detected on MRI performed immediately after thoracic fixation surgery, despite metal artifacts and findings such as hematoma causing spinal cord compression. Loss of CSF space should be considered to be associated with neurologic deficit.
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http://dx.doi.org/10.1016/j.wneu.2017.08.097DOI Listing
November 2017

Prognostic Factor Analysis for Management of Chronic Neck Pain: Can We Predict the Severity of Neck Pain with Lateral Cervical Curvature?

J Korean Neurosurg Soc 2017 Jul 31;60(4):456-464. Epub 2017 Jul 31.

Department of Neurological Surgery, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.

Objective: Although little is known about its origins, neck pain may be related to several associated anatomical pathologies. We aimed to characterize the incidence and features of chronic neck pain and analyze the relationship between neck pain severity and its affecting factors.

Methods: Between March 2012 and July 2013, we studied 216 patients with chronic neck pain. Initially, combined tramadol (37.5 mg) plus acetaminophen (325 mg) was administered orally twice daily (b.i.d.) to all patients over a 2-week period. After two weeks, patients were evaluated for neck pain during an outpatient clinic visit. If the numeric rating scale of the patient had not decreased to 5 or lower, a cervical medial branch block (MBB) was recommended after double-dosed previous medication trial. We classified all patients into two groups (mild vs. severe neck pain group), based on medication efficacy. Logistic regression tests were used to evaluate the factors associated with neck pain severity.

Results: A total of 198 patients were included in the analyses, due to follow-up loss in 18 patients. While medication was successful in reducing pain in 68.2% patients with chronic neck pain, the remaining patients required cervical MBB. Lateral cervical curvature, such as a straight or sigmoid type curve, was found to be significantly associated with the severity of neck pain.

Conclusion: We managed chronic neck pain with a simple pharmacological management protocol followed by MBB. We should keep in mind that it may be difficult to manage the patient with straight or sigmoid lateral curvature only with oral medication.
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http://dx.doi.org/10.3340/jkns.2015.0910.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5544378PMC
July 2017

Endovascular management of aneurysms associated with spinal arteriovenous malformations.

J Neurointerv Surg 2018 Feb 21;10(2):198-203. Epub 2017 Jun 21.

Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Background: Spinal aneurysms are rare among spinal arteriovenous malformations (SAVMs). There are few reports of endovascular management of spinal aneurysms associated with SAVM.

Objective: To present endovascular management of aneurysms associated with SAVM.

Methods: Of 91 patients with SAVMs,eight (9%) presented with aneurysms. Of these, three were male and five were female with a median age of 18 years (range 11-38). We evaluated the presenting pattern, lesion level, type of the target aneurysm related to the presenting pattern and AVM nidus, and the result obtained after embolization or open surgery. Clinical status was evaluated by Aminoff-Logue (ALS) gait and micturition scale scores.

Results: The presenting patterns were subarachnoid hemorrhage (SAH, n=3) or mass effect caused by extrinsic (n=4) or intrinsic (n=1) cord compression. Aneurysms were located in four cervical, two thoracic, and two lumbar enlargement areas. There were two prenidal (arterial), three nidal, and three postnidal (venous) aneurysms. The mean diameter of the aneurysms was 9 mm (range 3-27). Glue embolization (n=6), open surgery (n=1), and combined surgery and embolization (n=1) was performed to obliterate the aneurysms. Obliteration of the target aneurysms resulted in improvement of symptoms and clinical stabilization of SAVMs in all patients during a mean of 55 months (range 7-228) of follow-up.

Conclusions: Identification of a symptomatic aneurysm should be associated with clinical presentation pattern. Targeted obliteration of the aneurysm by embolization and/or surgery resulted in improvement of symptoms and stabilization of SAVM.
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http://dx.doi.org/10.1136/neurintsurg-2017-013150DOI Listing
February 2018

Widening of the safe trajectory range during subaxial cervical pedicle screw placement: advantages of a curved pedicle probe and laterally located starting point without creating a funnel-shaped hole.

J Neurosurg Spine 2017 Aug 19;27(2):150-157. Epub 2017 May 19.

Neurological Surgery, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.

OBJECTIVE The small diameter of cervical pedicles and a large transverse cervical pedicle angle are challenges that have led spinal surgeons to investigate how they could achieve a wider safety trajectory and reduce the insertion angle during cervical pedicle screw (CPS) placement. In this paper, the authors detail the advantages of using a curved pedicle probe and a laterally located entry point for overcoming these challenges. METHODS From March 2012 to May 2016, the authors performed posterior cervical fusions using CPSs on 119 consecutive patients. The lateral mass screw conversion and the CPS breach rate were analyzed. Using preoperative CT, it was determined that θ is similar to the anatomical pedicle angle, and θ is the minimally acceptable medial angle. The actual insertion medial angle (θ) was determined by postoperative CT. To identify how much of the medial angle on θ could be reduced from the anatomical pedicle angle (θ), and how much closer to θ, (θ-θ) / (θ-θ) was calculated. To verify shifting of the entry point and widening of the trajectory, the mean df/Df (i.e., shifted facet point/planned facet point) values were analyzed. RESULTS The total number of planed CPSs was 759, the conversion rate was 4.61% (35/759), and the accuracy rate was 95.9% (694/724). The authors could calculate that θ could be expected near the 90%, 80%, 80%, 80%, and 110% value of θ on C-3, C-4, C-5, C-6, and C-7 levels, respectively, with the (θ-θ) / (θ-θ) equation. The mean df/Df values were 0.64, 0.62, 0.63, 0.63, and 1.24 on the C3-7 levels, respectively. CONCLUSIONS Through the use of a curved pedicle probe and a laterally located starting point, the planned and laterally located entry point medial shift was made during CPS placement. The entry point shift yielded a wider, safe trajectory and reduced the burden of making a large medial angle, similar to an anatomical cervical pedicle lateral angle, for safe CPS placement without creating a funnel-shaped hole.
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http://dx.doi.org/10.3171/2016.12.SPINE16738DOI Listing
August 2017

Vertebral Artery Injury in C2-3 Epidural Schwannoma Resection: A Case Report and Literature Review.

Korean J Neurotrauma 2017 Apr 30;13(1):39-44. Epub 2017 Apr 30.

Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

The incidence of vertebral artery (VA) injury (VAI) in posterior approach tumor resection surgery is extremely rare, but it can lead to serious complication. In this case, a 57-year-old man underwent surgery for resection of the tumor involving left epidural space and neural foramen at C2-3 level. Iatrogenic VAI occurred suddenly during tumor resection procedure using pituitary forceps. Immediate local hemostasis and maintaining of perfusion for reducing the risk of posterior circulation ischemia were performed. Intraoperative angiogram of both VA and emergent trapping embolization were done as well. It may reduce the risk of immediate postop complication, and further delayed occurrence. The patient had no complication after VAI by appropriate intraoperative management. Preoperative angiographic work up and preparation of endovascular team cooperation are positively necessary as well as a warning for the VAI during cervical spine surgery.
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http://dx.doi.org/10.13004/kjnt.2017.13.1.39DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5432448PMC
April 2017

Postoperative Nonpathologic Fever After Spinal Surgery: Incidence and Risk Factor Analysis.

World Neurosurg 2017 Jul 2;103:78-83. Epub 2017 Apr 2.

Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Background: Although there are many postoperative febrile causes, surgical-site infection has always been considered as one of the major causes, but it should be excluded; we encountered many patients who showed delayed postoperative fever that was not related to wound infection after spinal surgery. We aimed to determine the incidence of delayed postoperative fever and its characteristics after spinal surgery, and to analyze the causal factors.

Methods: A total of 250 patients who underwent any type of spinal surgery were analyzed. We determined febrile patients as those who did not show any fever until postoperative day 3, and those who showed a fever with an ear temperature of greater than 37.8°C at 4 days after surgery. We collected patient data including age, sex, coexistence of diabetes mellitus or hypertension, smoking history, location of surgical lesion (e.g., cervical, thoracic, lumbar spine), type of surgery, surgical approach, diagnosis, surgical level, presence of revision surgery, operative time, duration of administration of prophylactic antibiotics, and the presence of transfusion during the perioperative period, with a chart review.

Results: There were 33 febrile patients and 217 afebrile patients. Multivariate logistic regression showed that surgical approach (i.e., posterior approach with anterior body removal and mesh graft insertion), trauma and tumor surgery compared with degenerative disease, and long duration of surgery were statistically significant risk factors for postoperative nonpathologic fever.

Conclusions: We suggest that most spinal surgeons should be aware that postoperative fever can be common without a wound infection, despite its appearance during the late acute or subacute period.
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http://dx.doi.org/10.1016/j.wneu.2017.03.119DOI Listing
July 2017

Risk Factors of Proximal Junctional Kyphosis after Multilevel Fusion Surgery: More Than 2 Years Follow-Up Data.

J Korean Neurosurg Soc 2017 Mar 1;60(2):174-180. Epub 2017 Mar 1.

Department of Neurosurgery, Inha University Hospital, Inha University School of Medicine, Incheon, Korea.

Objective: Proximal junctional kyphosis (PJK) is radiologic finding, and is defined as kyphosis of >10° at the proximal end of a construct. The aim of this study is to identify factors associated with PJK after segmental spinal instrumented fusion in adults with spinal deformity with a minimum follow-up of 2 years.

Methods: A total of 49 cases of adult spinal deformity treated by segmental spinal instrumented fusion at two university hospitals from 2004 to 2011 were enrolled in this study. All enrolled cases included at least 4 or more levels from L5 or the sacral level. The patients were divided into two groups based on the presence of PJK during follow-up, and these two groups were compared to identify factors related to PJK.

Results: PJK was observed in 16 of the 49 cases. Age, sex and mean follow-up duration were not statistically different between two groups. However, mean bone marrow density (BMD) and mean back muscle volume at the T10 to L2 level was significantly lower in the PJK group. Preoperatively, the distance between the C7 plumb line and uppermost instrumented vertebra (UIV) were no different in the two groups, but at final follow-up a significant intergroup difference was observed. Interestingly, spinal instrumentation factors, such as, receipt of a revision operation, the use of a cross-link, and screw fracture were no different in the two groups at final follow-up.

Conclusion: Preoperative BMD, sagittal imbalance at UIV, and thoracolumbar muscle volume were found to be strongly associated with the presence of PJK.
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http://dx.doi.org/10.3340/jkns.2016.0707.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5365283PMC
March 2017

Rod stiffness as a risk factor of proximal junctional kyphosis after adult spinal deformity surgery: comparative study between cobalt chrome multiple-rod constructs and titanium alloy two-rod constructs.

Spine J 2017 07 24;17(7):962-968. Epub 2017 Feb 24.

Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-2dong Songpa-Gu, Seoul, 138-736, Republic of Korea.

Background Context: Little is known about the effect of rod stiffness as a risk factor of proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery.

Purpose: The aim of this study was to compare radiographic outcomes after the use of cobalt chrome multiple-rod constructs (CoCr MRCs) and titanium alloy two-rod constructs (Ti TRCs) for ASD surgery with a minimum 1-year follow-up.

Study Design: Retrospective case-control study in two institutes.

Patient Sample: We included 54 patients who underwent ASD surgery with fusion to the sacrum in two academic institutes between 2002 and 2015.

Outcome Measures: Radiographic outcomes were measured on the standing lateral radiographs before surgery, 1 month postoperatively, and at ultimate follow-up. The outcome measures were composed of pre- and postoperative sagittal vertical axis (SVA), pre- and postoperative lumbar lordosis (LL), pre- and postoperative thoracic kyphosis (TK)+LL+pelvic incidence (PI), pre- and postoperative PI minus LL, level of uppermost instrumented vertebra (UIV), evaluation of fusion after surgery, the presence of PJK, and the occurrence of rod fracture.

Materials And Methods: We reviewed the medical records of 54 patients who underwent ASD surgery. Of these, 20 patients had CoCr MRC and 34 patients had Ti TRC. Baseline data and radiographic measurements were compared between the two groups. The Mann-Whitney U test, the chi-square test, and the Fisher exact test were used to compare outcomes between the groups.

Results: The patients of the groups were similar in terms of age, gender, diagnosis, number of three-column osteotomy, levels fused, bone mineral density, preoperative TK, pre- and postoperative TK+LL+PI, SVA difference, LL change, pre- and postoperative PI minus LL, and location of UIV (upper or lower thoracic level). However, there were significant differences in the occurrence of PJK and rod breakage (PJK: CoCr MRC: 12 [60%] vs. Ti TRC: 9 [26.5%], p=.015; occurrence of rod breakage: CoCr MRC: 0 [0%] vs. Ti TRC: 11 [32.4%], p=.004). The time of PJK was less than 12 months after surgery in the CoCr MRC group. However, 55.5% (5/9) of PJK developed over 12 months after surgery in the Ti TRC group.

Conclusions: Increasing the rod stiffness by the use of cobalt chrome rod and can prevent rod breakage but adversely affects the occurrence and the time of PJK.
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http://dx.doi.org/10.1016/j.spinee.2017.02.005DOI Listing
July 2017

Diagnostic Clue of Meningeal Melanocytoma: Case Report and Review of Literature.

Yonsei Med J 2017 Mar;58(2):467-470

Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

In this report, the patient was pre-diagnosed as meningioma before surgery, which turned out to be meningeal melanocytoma. Hence, we will discuss the interpretation of imaging and neurological statuses that may help avoid this problem. A 45-year-old man had increasing pain around the neck 14 months prior to admission. His cervical spine MR imaging revealed a space-occupying, contrast-enhancing mass within the dura at the level of C1. The neurologic examination revealed that the patient had left-sided lower extremity weakness of 4+, decreased sensation on the right side, and hyperreflexia in both legs. Department of Neuroradiology interpreted CT and MR imaging as meningiom. The patient underwent decompression and removal of the mass. We confirmed diagnosis as meningeal melanocytoma through pathologic findings. Afterwards, we reviewed the patient's imaging work-up, which showed typical findings of meningeal melanocytoma. However, it was mistaken as meningioma, since the disease is rare.
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http://dx.doi.org/10.3349/ymj.2017.58.2.467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5290031PMC
March 2017

Analysis of the Fusion and Graft Resorption Rates, as Measured by Computed Tomography, 1 Year After Posterior Cervical Fusion Using a Cervical Pedicle Screw.

World Neurosurg 2017 Mar 19;99:171-178. Epub 2016 Dec 19.

Department of Neurological Surgery, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea. Electronic address:

Background: We previously showed that cervical pedicle screw (CPS) placement is safe even with the freehand technique. The posterolateral fusion rate 1 year after CPS placement, as measured by computed tomography (CT), is reported here. The graft resorption rates when different graft materials were used were also analyzed.

Methods: Between 2012 and 2015, 93 patients underwent posterior cervical fusion surgery with the CPS from C2 to C7. Of these patients, 56 consented to CT scans immediately and 1 year after surgery. These patients formed the present study group. The patients were categorized according to whether the graft material was local bone, allograft, or a mixture. Graft volume was measured at both CT scans. Graft resorption rate was determined by comparing the 2 scans. Radiologic fusion was assessed on the 1 year postoperative CT scan and radiography.

Results: The reason for surgery was trauma (n = 19), degenerative disease (n = 35), tumor (n = 1), and spondylitis (n = 1). Surgery was performed with CPS fixation and decompression. Even although iliac bone grafting was not performed, the overall fusion rate was 98.2% (55/56). The single fusion failure case received a mixture of local bone and allograft. Although the allograft group showed the greatest graft resorption rate (91.5%), all patients in this group had a bony bridge that crossed the facet joint on the 1 year CT scan.

Conclusions: CPS placement yielded a posterolateral cervical fusion rate of 98.2%. Despite the high resorption rate of allograft only, this material yielded fusion rates that were similar to those of the other materials. Thus, the strong fixation power of CPS might compensate for the delayed fusion and high resorption rates of allograft bone chips.
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http://dx.doi.org/10.1016/j.wneu.2016.12.027DOI Listing
March 2017

Fatty Degeneration of the Paraspinal Muscle in Patients With Degenerative Lumbar Kyphosis: A New Evaluation Method of Quantitative Digital Analysis Using MRI and CT Scan.

Clin Spine Surg 2016 12;29(10):441-447

*Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam †Department of Neurosurgery, Seoul Chuk Hospital Departments of ‡Radiology §Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Study Design: A comparative case-control study.

Objective: The aim of this study was to quantify the degree of paraspinal muscle changes in degenerative lumbar kyphosis (DLK) patients using magnetic resonance imaging and computed tomography scanning.

Summary Of Background Data: Although the pathophysiology of DLK is not completely understood, extensive degeneration and weakness of the lumbar extensor muscles are thought to underlie the condition in most patients. However, there is no ideal method to quantify the degree of fat infiltration and atrophy of the paraspinal muscles in patients with DLK.

Materials And Methods: The study group comprised 20 patients with DLK and 20 healthy volunteers. The cross-sectional areas of the psoas, erector spinae (ES), multifidus (MF), quadratus lumborum, and vertebral body were measured. The ratio between the cross-sectional area of the muscle and the vertebral body was used to evaluate lumbar muscularity. The degree of fatty change was evaluated by measuring the ratio between the mean signal intensity of the muscle and that of the subcutaneous fat within regions of interest.

Results: Muscularity in the MF and ES was not significantly different between the DLK and control groups at L1, L2, or L3, but was significantly different at L4 (ES, P=0.001; MF, P=0.001) and L5 (ES, P=0.001; MF, P=0.015). The mean signal intensities of the ES and MF were higher in the DLK group than in the control group at all levels. The degree of fatty change in the ES and MF was significantly higher in the DLK group than in the control group (P<0.05).

Conclusions: Quantitative analysis using magnetic resonance imaging and computed tomography scanning showed differences in paraspinal muscle volume and fatty degeneration between patients with DLK and healthy volunteers. This evaluation method may be useful for measuring the extent of paraspinal muscle degeneration.
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http://dx.doi.org/10.1097/BSD.0b013e3182aa28b0DOI Listing
December 2016

Prognostic factor analysis after surgical decompression and stabilization for cervical spinal-cord injury.

Br J Neurosurg 2017 Apr 2;31(2):194-198. Epub 2016 Nov 2.

b Department of Neurological Surgery , Asan Medical Center, University of Ulsan College of Medicine , Seoul , Korea.

Introduction: Several studies have demonstrated the role of decompression surgery in preventing secondary injury and improving the neurological outcome after spinal cord injury (SCI). We retrospectively analyzed the prognostic factors affecting the outcomes of decompression surgery in patients with SCI.

Methods: We performed one-level decompression and fusion surgery on 73 patients with cervical SCI. We classified all patients based on their interval to decompression, sex, age, surgical level, presence of high signal intensity, American Spinal Injury Association Impairment scale (AIS) before surgery, blood pressure at admission, the amount of cord compression, surgical time, estimated blood loss during surgery, and steroid use. We considered an improvement to have occurred if the patient showed an AIS improvement of ≥1 grade.

Results: Among the 73 patients with SCI we analyzed, 27 and 35 showed ≥1 grade of AIS improvement immediately and 3 months after surgery, respectively. Using multivariate analysis, the mean arterial blood pressure (MAP) was a significant prognostic factor affecting recovery in the SCI patients during the immediate post-operative period. In the late recovery period at 3 months after surgery, the AIS before surgery and the MAP were significant prognostic factors affecting recovery.

Conclusions: Prognostic factors for AIS improvement include the initial neurological status before surgery and hemodynamic MAP at admission. The interval between decompression surgery and trauma does not affect the neurological outcome.
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http://dx.doi.org/10.1080/02688697.2016.1247781DOI Listing
April 2017

Response.

J Neurosurg Spine 2016 Apr;24(4):673

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April 2016

Decision Making Algorithm for Adult Spinal Deformity Surgery.

J Korean Neurosurg Soc 2016 Jul 8;59(4):327-33. Epub 2016 Jul 8.

Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Adult spinal deformity (ASD) is one of the most challenging spinal disorders associated with broad range of clinical and radiological presentation. Correct selection of fusion levels in surgical planning for the management of adult spinal deformity is a complex task. Several classification systems and algorithms exist to assist surgeons in determining the appropriate levels to be instrumented. In this study, we describe our new simple decision making algorithm and selection of fusion level for ASD surgery in terms of adult idiopathic idiopathic scoliosis vs. degenerative scoliosis.
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http://dx.doi.org/10.3340/jkns.2016.59.4.327DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4954878PMC
July 2016

Clinical analysis of C5 palsy after cervical decompression surgery: relationship between recovery duration and clinical and radiological factors.

Eur Spine J 2017 04 24;26(4):1101-1110. Epub 2016 Jun 24.

Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea.

Background: Postoperative C5 palsy is a widely known complication of cervical decompression surgery. Many studies have focused on its etiology and factors affecting it. However, no study to date has evaluated the association between the clinical outcome and recovery duration of post-operative C5 palsy. We evaluated this in our current report.

Methods: A retrospective analysis was conducted for 710 consecutive degenerative cervical spine decompression surgeries performed in a single institution. We included all patients who underwent any type of surgical procedure for cervical spinal stenosis, ossification of posterior longitudinal ligament (OPLL), or cervical spondylotic myelopathy (CSM). Demographic, radiologic, clinical information was recorded. Finally, correlation analysis was conducted to identify demographic, radiologic, or clinical factors related with recovery duration (within or after 6 months).

Results: The incident rate of postoperative C5 palsy was 5.1 % (36/710 cases). Analysis of recovery duration revealed that 18 patients had recovered within 6 months and 33 (91.7 %) within 2 years, whilst 3 individuals (8.3 %) had not fully recovered within the follow-up period. Factors related to longer recovery (>6 months) included motor grade ≤2 (p < 0.001), presence of multi-segment paresis involving more than the C5 root (p = 0.002), loss of somatic sensation with pain (p = 0.008), and the degree of posterior spinal cord shifting (p = 0.040). Furthermore, multivariate analysis revealed that motor grade ≤2 (p = 0.010) had a significant effect on a recovery duration beyond 6 months.

Conclusions: A motor grade ≤2, the presence of multi-segment paresis involving more than the C5 root, the loss of somatic sensation with pain, and the degree of posterior spinal cord shifting significantly influence whether the duration of recovery from postoperative C5 palsy will take longer than 6 months.
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http://dx.doi.org/10.1007/s00586-016-4664-4DOI Listing
April 2017

Patients with proximal junctional kyphosis after stopping at thoracolumbar junction have lower muscularity, fatty degeneration at the thoracolumbar area.

Spine J 2016 09 20;16(9):1095-101. Epub 2016 May 20.

Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-2dong Songpa-Gu, Seoul, 138-736, Republic of Korea. Electronic address:

Background Context: There are several reports regarding pathogeneses and risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity surgery. However, the relationship between thoracolumbar muscle condition and PJK has not been investigated yet.

Purpose: We aimed to elucidate the thoracolumbar muscle conditions on the incidence of PJK in adult patients with spinal deformity treated by long instrumented spinal fusion surgery stopping at thoracolumbar junction with a minimum 2-year follow-up (F/U).

Study Design: This is a retrospective review of prospective database.

Patient Sample: A total of 44 cases of patients having multilevel spinal instrumented fusion stopping at thoracolumbar junction for adult spinal deformity in two academic institutions from 2004 to 2012 were enrolled in this study.

Outcome Measures: For clinical outcomes, the Scoliosis Research Society questionnaire-22r (SRS-22r) was used preoperatively and at ultimate F/U.

Methods: Inclusion criteria were age >20 and minimum five vertebrae fused from T9 upper instrumented vertebra (UIV) to any lower instrumented vertebra. Radiographic assessment included pelvic parameters, Cobb measurements in the coronal-sagittal plane, and measurements of the thoracolumbar muscularity (cross-sectional area of muscle-vertebral body ratio×100) and fatty degeneration (signal intensity of muscle-subcutaneous fat ratio×100).

Results: The prevalence of PJK was 38.6%. Age at surgery, gender, fusions extending to the sacrum, levels fused, combined anterior-posterior surgery, and a UIV level were not significantly different between PJK and non-PJK groups. Lower bone mineral density (BMD; T-score: -2.5 vs. -1.3, p=.003) and lower muscularity and higher fatty degeneration at the level of T10 to L2 (131.8 vs. 159.0, p<.01; 59.0 vs. 44.0, p<.001, respectively) were identified risk factors for PJK. Radiographic parameters demonstrated a higher postoperative lumbar lordosis (LL) change (43.8 vs. 29.3, p<.001) and a larger sagittal vertical axis (SVA) change with surgery (8.4 cm vs. 4.8 cm, p=.01) in those with PJK. Although SRS postop pain scores were inferior in PJK group (3.3 vs. 4.1, p<.05), there were no significant differences in the average scores between the groups (3.5 vs. 3.3, p<.05).

Conclusions: Patients with PJK had lower thoracolumbar muscularity and higher fatty degeneration than patients without PJK before surgery. Our data suggest that osteoporosis, large corrections in LL and SVA with surgery, and lower muscularity and higher fatty degeneration at the thoracolumbar area can lead to PJK.
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http://dx.doi.org/10.1016/j.spinee.2016.05.008DOI Listing
September 2016

Clinical presentation, imaging findings, and prognosis of spinal dural arteriovenous fistula.

J Clin Neurosci 2016 Apr 4;26:105-9. Epub 2016 Jan 4.

Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43 Gil, Songpa-gu, Seoul 138-736, Republic of Korea. Electronic address:

Spinal dural arteriovenous fistula (SDAVF) is a relatively common acquired vascular malformation of the spinal cord. Assessment of a SDAVF is often difficult because of non-specific findings on non-invasive imaging modalities. Diagnosis of a SDAVF is often delayed, and some patients receive unnecessary treatment and treatment delays, often resulting in a poor outcome. The aim of this study was to characterize the clinical presentation, typical imaging findings, and long-term outcome of SDAVF. Forty patients (13 women, 27 men; mean age 58.18 ± standard deviation 14.75 years) who were treated at our hospital from June 1992 to March 2014 were retrospectively reviewed. We investigated the baseline characteristics, clinical presentation, imaging findings, treatment modalities, and outcome of the patients. The most common clinical presentation was a sensory symptom (80%), followed by motor weakness (70%), and sphincter dysfunction (62.5%). Roughly one-third (32.5%) of patients had a stepwise progression of fluctuating weakness and sensory symptoms, but the most common presentation was chronic progressive myelopathic symptoms (47.5%). Thirty-four patients (85%) had T2 signal change on the spinal cord MRI, indicative of cord edema. Thirty-eight patients had typical perimedullary vessel flow voids on T2-weighted MRI. Twenty-eight patients were treated with endovascular embolization, five patients underwent surgery, and four patients underwent both. Clinical outcome was determined by severity of initial deficit (p=0.008), extent of cord edema (p=0.010), treatment failure (p=0.004), and a residual fistula (p=0.017). SDAVF causes a treatable myelopathy, so early diagnosis and intervention is essential.
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http://dx.doi.org/10.1016/j.jocn.2015.06.030DOI Listing
April 2016

Advantages of Direct Insertion of a Straight Probe Without a Guide Tube During Anterior Odontoid Screw Fixation of Odontoid Fractures.

Spine (Phila Pa 1976) 2016 May;41(9):E541-7

*Department of Neurological Surgery†Department of Neurology‡Department of Anesthesiology§Department of Emergency Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung¶Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul||Department of Neurological Surgery, Gyeongsang National University School of Medicine, Jinju, Korea.

Study Design: A retrospective cohort study.

Objective: The aim of this study was to compare the anterior odontoid screw fixation (AOSF) with a guide tube or with a straight probe.

Summary Of Background Data: AOSF associates with several complications, including malpositioning, fixation loss, and screw breakage. Screw pull-out from the C2 body is the most common complication.

Methods: All consecutive patients with type II or rostral shallow type III odontoid fractures who underwent AOSFs during the study period were enrolled retrospectively. The guide-tube AOSF method followed the standard published method except C3 body and C2-3 disc annulus rimming was omitted to prevent disc injury; instead, the guide tube was anchored at the anterior inferior C2 vertebra corner. After 2 screw pull-outs, the guide-tube cohort was analyzed to identify the cause of instrument failure. Thereafter, the straight-probe method was developed. A guide tube was not used. A small pilot hole was made on the most anterior side of the inferior endplate, followed by insertion of a 2.5 mm straight probe through the C2 body. Non-union and instrument failure rates and screw-direction angles of the guide-tube and straight-probe groups were recorded.

Results: The guide-tube group (n = 13) had 2 screw pull-outs and 1 non-union. The straight-probe group (n = 8) had no complications and significantly larger screw-direction angles than the guide-tube group (60.5 ± 4.63 vs. 54.8 ± 3.82 degrees; P = 0.047).

Conclusion: Straight-probe AOSF yielded larger direction angles without injuring bone and disc. Complications were absent. The procedure was easier than guide-tube AOSF and assured sufficient engagement, even in horizontal fracture orientation cases.

Level Of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000001311DOI Listing
May 2016
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