Hyun Chul Shin

Postoperative Spinal Epidural Hematoma: Risk Factor and Clinical Outcome

We report a series of epidural hematomas which cause neurologic deterioration after spinal surgery, and have taken risk factors and prognostic factors into consideration. We retrospectively reviewed the database of 3720 cases of spine operation in a single institute over 7 years (1998 April-2005 July). Nine patients who demonstrated neurologic deterioration after surgery and required surgical decompression were identified. Factors postulated to increase the postoperative epidural hematoma and to improve neurologic outcome were investigated. The incidence of postoperative epidural hematoma was 0.24%. Operation sites were cervical 3 cases, thoracic 2 cases, and lumbar 4 cases. Their original diagnoses were tumor 3 cases, cervical stenosis 2 cases, lumbar stenosis 3 cases and herniated lumbar disc 1case. The symptoms of epidural hematomas were neurologic deterioration and pain. After decompression, clinical outcome revealed complete recovery in 3 cases (33.3%), incomplete recovery in 5 cases (55.6%) and no change in 1 case (11.1%). Factors increasing the risk of postoperative epidural hematoma were coagulopathy from medical illness or anticoagulation therapy (4 cases, 44.4%) and highly vascularized tumor (3 cases, 33.3%). The time interval to evacuation of complete recovery group (29.3 hours) was shorter than incomplete recovery group (66.3 hours). Patients with coagulopathy and highly vascularized tumor were more vulnerable to spinal epidural hematoma. The postoperative outcome was related to the preoperative neurological deficit and the time interval to the decompression.

Difference in Occurrence of Heterotopic Ossification According to Prosthesis Type in the Cervical Artificial Disc Replacement

Study Design. Retrospective study of the difference of heterotopic ossification (HO) occurrence according to 3 different types of prosthesis. Objective. This study was designed to investigate the difference of HO occurrence according to different type of prosthesis. Summary of Background Data. HO is defined as formation of the bone outside the skeletal system. Reported HO occurrence rate in cervical artificial disc replacement (ADR) was unexpectedly high and varied. But the influencing factors of HO in cervical ADR have not been elucidated well. The prosthesis-related factors for making difference of HO occurrence were investigated in this study. Methods. A total of 170 patients undergoing cervical arthroplasty with the Bryan cervical disc prosthesis (Medtroic Sofamor Danek, Memphis, TN), Mobi-C disc prosthesis (LDR Medical, Troyes, France), and ProDisc-C (Synthes, Inc., West Chester, PA) were included. Cervical lateral radiographs obtained before and after surgery were used to identify HO. Occurrence rate, occurrence-free period, location, and grade of HOs were investigated according to the different prosthesis. Results. Each prosthesis group included patients as follows: Bryan disc, 81 patients; Mobi-C, 61 patients; and ProDisc-C, 28 patients. Overall HO rate was 40.6% (69 of 170 patients). Each HO occurrence rate by prosthesis was as follows: the Bryan disc group, 21.0%; Mobi-C group, 52.5%; and the ProDisc-C group, 71.4%. In the survival analysis, all patients showed 27.1 ± 3.7 months as the median survival. The Bryan disc group showed statistically longer survival (48.4 ± 7.4 months) than the other groups. Conclusion. Occurrence of HO is an inevitable postoperative complication after cervical ADR. The occurrence rate of HO was higher than our expectation. Moreover, definite differences in occurrence rate according to the prosthesis type were identified by this study.

Modified Techniques to Prevent Sagittal Imbalance After Cervical Arthroplasty

Study Design. Retrospective study of radiographic outcomes in patients undergoing single level cervical arthroplasty with the Bryan cervical disc (Medtronic Sofamor Danek, Memphis, TN). Objective. This study was designed to determine whether modification of disc insertion angle and insertion depth are effective in preventing segmental or whole cervical kyphosis after arthroplasty. Summary of Background Data. Preservation of segmental motion and aggravation of kyphosis are known challenges after arthroplasty. However, there are currently no proven preventative factors for kyphosis. Change in disc insertion angle was only reported effective for avoiding endplate kyphosis. Additionally, it was difficult to predict the effect of insertion angle on overall sagittal alignment. There have been no studies regarding the correlation between insertion depth and sagittal alignment. Methods. A total of 41 patients with single-level arthroplasty were evaluated. Radiologic assessment using neutral cervical radiographs at the long-term was performed. Linear regression analysis between insertion angle, insertion depth, postoperative sagittal alignment, functional spinal unit angle, and shell angle were performed. Results. Disc insertion angle and insertion depth demonstrated significant negative correlation with the postoperative shell angle. Lordotic insertion angle and an anteriorly located disc led to lordosis in the shell angle. Overall sagittal alignment showed a tendency to correlate with insertion angle. By the result of effect of insertion angle ranging from 3.5° to 7.5° on the sagittal alignment and shell angle, we can hypothesize paradoxical biomechanical stress on the other segments. Conclusion. Arthroplasty using the Bryan disc provided a favorable clinical and radiologic outcome thus far; however, we should not underestimate emergent adverse outcomes. To prevent postoperative sagittal imbalance after cervical arthroplasty, intentional modification in disc insertion angle and depth would be helpful. Unexpected compensatory biomechanical loads should be elucidated in future studies.

The predisposing factors for the heterotopic ossification after cervical artificial disc replacement

BACKGROUND CONTEXT Heterotopic ossification (HO) is defined as a formation of bone outside the skeletal system. The reported HO occurrence rate in cervical artificial disc replacement (ADR) is unexpectedly high and is known to vary. However, the predisposing factors for HO in cervical ADR have not yet been elucidated. PURPOSE Investigation of the predisposing factors of HO in cervical arthroplasty and the relationship between degeneration of the cervical spine and HO occurrence. STUDY DESIGN Retrospective study to discover predisposing factors of HO in cervical arthroplasty. PATIENT SAMPLE A total of 170 patients who underwent cervical ADR were enrolled including full follow-up clinical and radiologic data. OUTCOME MEASURES Radiologic outcomes were assessed by identification of HOs according to McAfees classifications. METHODS This study enrolled a total of 170 patients who underwent cervical ADR. Pre-existing degenerative change included anterior or posterior osteophytes, ossification of the anterior longitudinal ligament, posterior longitudinal ligament, or ligamentum nuchae. The relationships between basic patient data, pre-existing degenerative change, and HO were investigated using linear logistic regression analysis. RESULTS Among all 170 patients, HO was found in 69 patients (40.6%). Among the postulated predisposing factors, only male gender and artificial disc device type were shown to be statistically significant. Unexpectedly, preoperative degenerative changes in the cervical spine exerted no significant influence on the occurrence of HOs. The odds ratio of male gender compared with female gender was 2.117. With regard to device type, the odds ratios of Mobi-C (LDR medical, Troyes, France) and ProDisc-C (Synthes, Inc., West Chester, PA, USA) were 5.262 and 7.449, respectively, compared with the Bryan disc. CONCLUSIONS Definite differences in occurrence rate according to the gender of patients and the prosthesis type were identified in this study. Moreover, factors indefinably expected to influence HO in the past were not shown to be risk factors thereof, the results of which may be meaningful to future studies.

Surgical outcome and prognostic factors of anterior decompression and fusion for cervical compressive myelopathy due to ossification of the posterior longitudinal ligament

BACKGROUND CONTEXT Anterior decompression and fusion (ADF) for ossification of the posterior longitudinal ligament (OPLL) is technically demanding and associated with complications. Although various factors affecting clinical outcome have been investigated in posterior decompression, prognostic factors of ADF remain unclear. PURPOSE The purpose of the study was to identify surgical outcome and prognostic factors of ADF for cervical myelopathy due to OPLL. STUDY DESIGN This was a retrospective case study. PATIENT SAMPLE Between 2005 and 2012, 913 patients underwent decompression surgery for cervical OPLL at our institution. Among them, 131 who underwent ADF and 221 who underwent laminoplasty were enrolled. Inclusion criteria were (1) diagnosis of OPLL; (2) cervical compressive myelopathy; and (3) no trauma, infection, tumor, or previous surgery. We excluded 60 patients with ADF and 157 patients with laminoplasty owing to inadequate follow-up or absence of preoperative myelopathy. Finally, 71 patients with ADF and 64 patients with laminoplasty were enrolled in this study (mean follow-up, 48 vs 41 months). OUTCOME MEASURES Neurologic assessment was conducted using the Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy. Rate of neurologic improvement was calculated by comparing preoperative and postoperative JOA scores. METHODS We investigated the effects of such variables as age, gender, body mass index (BMI), presence of diabetes mellitus (DM), smoking history, type of OPLL, shape of the ossified lesion, occupying ratio of OPLL, presence of intramedullary increased signal intensity (ISI) on magnetic resonance imaging (MRI), and sagittal alignment of the cervical spine on surgical outcome. Severity of ISI was classified into three groups based on T2-weighted sagittal MRI as follows: Grade 0, none; Grade 1, ISI limited to one disc level; or Grade 2, ISI beyond one disc level. This work was supported by the 2013 Korea Health Technology R&D Project of the Ministry of Health and Welfare of the Republic of Korea (A120254). RESULTS In patients with an occupying ratio ≥60% or with presence of ISI on MRI, ADF yielded better surgical outcome than laminoplasty. A higher ISI grade (B=-28.5, p=.000) and a higher occupying ratio (B=0.88, p=.04) were significantly associated with a lower recovery rate (R=0.56, p=.006). Older age also was associated with a lower recovery rate. Gender, BMI, presence of DM, smoking history, type of OPLL, shape of the ossified lesion, and cervical alignment were not associated with recovery rate. CONCLUSION Anterior decompression and fusion has favorable outcome in patients with an occupying ratio ≥60% or with presence of ISI on MRI. Presence of higher ISI grade, higher occupying ratio, and older age were associated with a poor long-term surgical prognosis. Therefore, evaluating ISI and occupying ratio on preoperative MRI is important for selecting the appropriate surgical approach and for predicting clinical outcome after surgery for cervical compressive myelopathy due to OPLL.

Comparison of Serum CRP and Procalcitonin in Patients after Spine Surgery

OBJECTIVE Classical markers of infection cannot differentiate reliably between inflammation and infection after neurosurgery. This study investigated the dynamics of serum procalcitonin (PCT) in patients who had elective spine surgeries without complications. METHODS Participants were 103 patients (47 women, 56 men) who underwent elective spinal surgery. Clinical variables relevant to the study included age, sex, medical history, body mass index (BMI), site and type of surgery, and surgery duration. Clinical and laboratory data were body temperature, white blood cell count (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and PCT, all measured preoperatively and postoperatively on days 1, 3, and 5. RESULTS PCT concentrations remained at <0.25 ng/mL during the postoperative course except in 2 patients. PCT concentrations did not correlate with age, sex, DM, hypertension, BMI, operation time, operation site, or use of instrumentation. In contrast, CRP concentrations were significantly higher with older age, male, DM, hypertension, longer operation time, cervical operation, and use of instrumentation. CONCLUSION PCT may be useful in the diagnosing neurosurgical patients with postoperative fever of unknown origin.

Posterior Lumbar Interbody Fusion via a Unilateral Approach

This study sought to determine the outcomes of posterior lumbar interbody fusion (PLIF), via a unilateral approach, in selected patients who presented with unilateral leg pain and segmental instability of the lumbar spine. Patients with a single level of a herniated disc disease in the lumbar spine, unilateral leg pain, chronic disabling lower back pain (LBP), and a failed conservative treatment, were considered for the procedure. A total of 41 patients underwent a single-level PLIF using two PEEK™ (Poly-Ether-Ether-Ketone) cages filled with iliac bone, via a unilateral approach. The patients comprised 21 women and 20 men with a mean age of 41 years (range: 22 to 63 years). Two cages were inserted using a unilateral medial facetectomy and a partial hemilaminectomy. At follow-up, the outcomes were assessed using the Prolo Scale. The success of the fusion was determined by dynamic lumbar radiography and/or computerized tomography scanning. All the patients safely underwent surgery without severe complications. During a mean follow-up period of 26 months, 1 patient underwent percutaneous pedicle screw fixation due to persistent LBP. A posterior displacement of the cage was found in one patient. At the last follow up, 90% of the patients demonstrated satisfactory results. An osseous fusion was present in 85% of the patients. A PLIF, via a unilateral approach, enables a solid union with satisfactory clinical results. This preserves part of the posterior elements of the lumbar spine in selected patients with single level instability and unilateral leg pain.

Intraoperative indocyanine green video-angiography: spinal dural arteriovenous fistula.

Study Design. Technical note. Objective. To describe the use of intraoperative indocyanine green (ICG) video-angiography for obliteration of a spinal dural arteriovenous fistula (DAVF) and to show a video clip. Summary of Background Data. ICG video-angiography is an emerging tool for delineating intraoperative vascular anatomy, and it has a significant potential in the treatment of vascular diseases in the spine. Methods. The authors presented a case of a 73-year-old man with progressive and debilitating bilateral lower extremity weakness. The patient was diagnosed with a spinal DAVF of 10th thoracic spine based on the results of conventional spinal angiography. Results. The patient underwent T9–10 laminotomy for microsurgical clip occlusion. Intraoperative ICG video-angiography was used before clip placement to identify the arterialized veins of the fistula and after clip placement to confirm obliteration of the fistulous connection and restoration of normal blood flow. Conclusion. Intraoperative ICG video-angiography serves an important role in the microsurgical treatment of DAVF. It is simple and provides real-time information about the precise location of spinal DAVF and result after obliteration of spinal DAVF.

Correlation between cervical spine sagittal alignment and clinical outcome after cervical laminoplasty for ossification of the posterior longitudinal ligament

OBJECTIVE The goal of this study was to determine the relationship between cervical spine sagittal alignment and clinical outcomes after cervical laminoplasty in patients with ossification of the posterior longitudinal ligament (OPLL). METHODS Fifty consecutive patients who underwent a cervical laminoplasty for OPLL between January 2012 and January 2013 and who were followed up for at least 1 year were analyzed in this study. Standing plain radiographs of the cervical spine, CT (midsagittal view), and MRI (T2-weighted sagittal view) were obtained (anteroposterior, lateral, flexion, and extension) pre- and postoperatively. Cervical spine alignment was assessed with the following 3 parameters: the C2-7 Cobb angle, C2-7 sagittal vertical axis (SVA), and T-1 slope minus C2-7 Cobb angle. The change in cervical sagittal alignment was defined as the difference between the post- and preoperative C2-7 Cobb angles, C2-7 SVAs, and T-1 slope minus C2-7 Cobb angles. Outcome assessments (visual analog scale [VAS], Oswestry Neck Disability Index [NDI], 36-Item Short-Form Health Survey [SF-36], and Japanese Orthopaedic Association [JOA] scores) were obtained in all patients pre- and postoperatively. RESULTS The average patient age was 56.3 years (range 38-72 years). There were 34 male patients and 16 female patients. Cervical laminoplasty for OPLL helped alleviate radiculomyelopathy. Compared with the preoperative scores, improvement was seen in postoperative VAS and JOA scores. After laminoplasty, 35 patients had kyphotic changes, and 15 had lordotic changes. However, cervical sagittal alignment after laminoplasty was not significantly associated with clinical outcomes in terms of postoperative improvement of the JOA score (C2-7 Cobb angle: p = 0.633; C2-7 SVA: p = 0.817; T-1 slope minus C2-7 lordosis: p = 0.554), the SF-36 score (C2-7 Cobb angle: p = 0.554; C2-7 SVA: p = 0.793; T-1 slope minus C2-7 lordosis: p = 0.829), the VAS neck score (C2-7 Cobb angle: p = 0.263; C2-7 SVA: p = 0.716; T-1 slope minus C2-7 lordosis: p = 0.497), or the NDI score (C2-7 Cobb angle: p = 0.568; C2-7 SVA: p = 0.279; T-1 slope minus C2-7 lordosis: p = 0.966). Similarly, the change in cervical sagittal alignment was not related to the JOA (p = 0.604), SF-36 (p = 0.308), VAS neck (p = 0.832), or NDI (p = 0.608) scores. CONCLUSIONS Cervical laminoplasty for OPLL improved radiculomyelopathy. Cervical laminoplasty increased the probability of cervical kyphotic alignment. However, cervical sagittal alignment and clinical outcomes were not clearly related.

Stand-alone cervical cages versus anterior cervical plate in 2-level cervical anterior interbody fusion patients: clinical outcomes and radiologic changes.

Study Design: Retrospective study. Objectives: To compare the efficacy of 2-level anterior cervical discectomy and fusion with cage alone (ACDF-CA) and with cage and plate construct (ACDF-CPC) with regard to clinical outcome and radiologic changes. Summary of Background Data: The use of stand-alone cervical interbody cages in ACDF has become popular, but high subsidence rates have been reported in the literature. Methods: A total of 54 consecutive patients who underwent 2-level ACDF-CA or ACDF-CPC after suffering from cervical radiculopathy were divided into 2 groups: group A (n=28) underwent ACDF-CA, group B (n=26) underwent ACDF-CPC. Fusion rate, global and segmental kyphosis, disk height, and subsidence rate were assessed by radiolographs. Clinical outcomes were assessed using Robinson’s criteria. Results: Solid fusion was achieved in 96.43% (27/28) in group A and in 96.15% (25/26) in group B. Fusion segmental kyphosis of >5 degrees occurred in 14.29% (4/28) of group A and in 7.69% (2/26) of group B; however, there was no statistical difference between the 2 groups (P>0.05). Subsidence occurred in 35.71% (10/28) of group A as compared with 11.54% (3/26) of group B (P<0.05). Clinical outcomes were similar in the 2 treatment groups. Conclusions: The use of cage and plate construct in 2-level ACDF results in a shorter fusion duration and a lower subsidence rate than that of cage alone; however, there is no significant difference in the postoperative global and segmental alignment and clinical outcomes between groups.