Prediction of Shunt-Dependent Hydrocephalus after Primary Supratentorial Intracerebral Hemorrhage with a Focus on the Influence of Craniectomies

Objective@#: Hydrocephalus after intracerebral hemorrhage (ICH) is known to be related to poor prognosis and mortality. We analyzed predictors of permanent hydrocephalus in the patients with surgically treated supratentorial ICH. @*Methods@#: From 2004 to 2019, a total of 414 patients with surgically treated primary supratentorial ICH were included. We retrospectively analyzed age, sex, preexisting hypertension and diabetes, location and volume of ICH, presence and severity of intraventricular hemorrhage (IVH), and type of surgery. @*Results@#: Forty patients (9.7%) required shunt surgery. Concomitant IVH was higher in the ‘shunt required’ group (92.5%) than in the ‘shunt not required’ group (67.9%) (p=0.001). IVH severity was worse in the ‘shunt required’ group (13.5 vs. 7.5, p=0.008). Craniectomy (47.5%) was significantly high in the ‘shunt required’ group. According to multivariable analysis, the presence of an IVH was 8.1 times more frequent and craniectomy was 8.6 times more frequent in the ‘shunt required’ group. In the comparison between craniotomy and craniectomy group, the presence of an IVH was related with a 3.9 times higher (p=0.033) possibility and craniectomies rather than craniotomies with a 7-times higher possibility of shunt surgery (p<0.001). Within the craniectomy group, an increase in the craniectomy area by 1 cm2 was correlated with a 3.2% increase in the possibility of shunt surgery (odds ratio, 1.032; 95% confidence interval, 1.005-1.061; p=0.022). @*Conclusion@#: Presence of IVH, the severity of IVH and decompressive craniectomy were related to the development of shunt dependent hydrocephalus in the patients with ICH. The increasing size of craniectomy was related with increasing rate of shunt requirement.

Acute cerebral infarction combined with a thyroid storm in a patient with both Moyamoya syndrome and Graves’ disease

Moyamoya syndrome (MMS) associated with hyperthyroidism, such as Graves’ disease, is a rare condition that causes ischemic stroke with thyrotoxicity. A 43-year-old woman with symptoms of right hemiparesis was admitted. Brain magnetic resonance imaging revealed a small cerebral infarction in the left frontal lobe. Cerebral angiography revealed multi-vessel intracranial occlusive disease. Several days later, neurologic deterioration and aggravation of cerebral infarction developed due to a thyroid storm. A thyroid function test revealed the following: thyroid-stimulating hormone (TSH) ＜0.01 μunits/mL (reference range, 0.55–4.78 μunits/mL); triiodo-thyronine ＞8.0 ng/mL (reference range, 0.77–1.81 ng/mL); free thyroxine (T4) of 9.47 pmol/L (reference range, 11.4–22.6 pmol/L); and TSH receptor antibody of 37.10 U/L (reference range, 0–10 U/L). For thyroid storm management, we initiated treatment with methimazole, Gemstein’s solution, and hydrocortisone. Finally, the thyroid disease was controlled, and neurologic deficits improved. We describe a case of acute cerebral infarction combined with a thyroid storm in a patient with Moyamoya syndrome and Graves’ disease. Hyperthyroidism such as Graves’ disease should be considered in the differential diagnosis for patho-etiologic mechanisms associated with MMS. A cerebrovascular disease with a thyroid storm can lead to severe mortality and morbidity. Prompt diagnosis and strict treatment are important.

Comparison of Postoperative Complications between Simultaneous and Staged Surgery in Cranioplasty and Ventriculoperitoneal Shunt Placement after Decompressive Craniectomy / 대한신경손상학회지

Objective@#Cranioplasty (CP) and ventriculoperitoneal shunt (VPS) are required procedures following decompressive craniectomy (DC) for craniofacial protection and to prevent hydrocephalus. This study assessed the safety and efficacy of simultaneous operation with CP and VPS after DC, and determined the preoperative risk factors for postoperative complications. @*Methods@#Between January 2009 and December 2019, 81 patients underwent CP and VPS in simultaneous or staged operations following DC. Cumulative medical records and radiologic data were analyzed using univariate analysis to identify factors predisposing patients to complications after CP and VPS. @*Results@#CP and VPS were performed as simultaneous or staged operations in 18 (22.2%) and 63 (77.8%) patients, respectively. The overall postoperative complication rate was 16.0% (13/81). Patients who underwent simultaneous CP and VPS were significantly more likely to experience complications when compared with patients who underwent staged operations (33.3% vs. 9.6%, p<0.01). Univariate analysis revealed that simultaneous CP and VPS surgery was the only significant predictor of postoperative complications (p=0.031). @*Conclusion@#This study provided detailed data on surgical timing and complications for CP and VPS after DC. We showed that simultaneous procedures were a significant risk factor for postoperative complications.

The Effect of Locally Administered Fibrinolytic Drugs Following Aneurysmal Subarachnoid Hemorrhage : A Meta-Analysis with Eight Randomized Controlled Studies

Objective@#: Rapid dissolution of blood clots reduces vasospasm and hydrocephalus after subarachnoid hemorrhage (SAH), and locally administered fibrinolytic drugs (LAFDs) could facilitate the dissolution. However, the efficacy of LAFDs remains controversial. The aim of this meta-analysis was to determine the efficacy of LAFDs for vasospasm and hydrocephalus and in clinical outcomes. @*Methods@#: From PubMed, EMBASE, and Cochrane database, data were extracted by two authors. Meta-analysis was performed using a random effect model. Inclusion criteria were patients who had LAFDs with urokinase-type or recombinant tissue-plasminogen activator after SAH in comparison with medically untreated patients with fibrinolytic drugs. We only included randomized controlled trials (RCTs) in this analysis. The outcomes of interest were vasospasm, hydrocephalus, mortality, and 90-day unfavorable functional outcome. @*Results@#: Data from eight RCTs with 550 patients were included. Pooled-analysis revealed that the LAFDs were significantly associated with lower rates of vasospasm (LAFDs group vs. control group, 26.5% vs. 39.2%; odds ratio [OR], 0.48; 95% confidence interval [CI], 0.32–0.73); hydrocephalus (LAFDs group vs. control group, 26.0% vs. 31.6%; OR, 0.54; 95% CI, 0.32–0.91); and mortality (LAFDs group vs. control group, 10.5% vs. 15.7%; OR, 0.58; 95% CI, 0.34–0.99). The proportion of 90-day unfavorable outcomes was lower in the LAFDs group (LAFDs group vs. control group, 32.7% vs. 43.5%; OR, 0.55; 95% CI, 0.37–0.80). @*Conclusion@#: This meta-analysis with eight RCTs indicated that LAFDs were significantly associated with lower rates of vasospasm and hydrocephalus after SAH. Thus, LAFDs could consequently reduce mortality and improve clinical outcome after SAH.

Clinical Pathway for Emergency Brain Surgery during COVID-19 Pandemic and Its Impact on Clinical Outcomes

Background@#One of the challenges neurosurgeons are facing in the global public health crisis caused by the coronavirus disease 2019 (COVID-19) pandemic is to balance COVID-19 screening with timely surgery. We described a clinical pathway for patients who needed emergency brain surgery and determined whether differences in the surgery preparation process caused by COVID-19 screening affected clinical outcomes. @*Methods@#During the COVID-19 period, patients in need of emergency brain surgery in our institution were managed using a novel standardized pathway designed for COVID-19 screening. We conducted a retrospective review of patients who were hospitalized through the emergency room and underwent emergency brain surgery. A total of 32 patients who underwent emergency brain surgery from February 1 to June 30, 2020 were included in the COVID-19 group, and 65 patients who underwent surgery from February 1 to June 30, 2019 were included in the pre-COVID-19 group. The baseline characteristics, disease severity indicators, time intervals of emergency processes, and clinical outcomes of the two groups were compared. Subgroup analysis was performed between the immediate surgery group and the semi-elective surgery group during the COVID-19 period. @*Results@#There were no significant differences in baseline characteristics and severity indicators between the pre-COVID-19 group and COVID-19 group. The time interval to skin incision was significantly increased in the COVID-19 group (P = 0.027). However, there were no significant differences in the clinical outcomes between the two groups. In subgroup comparison, the time interval to skin incision was shorter in the immediate surgery group during the COVID-19 period compared with the pre-COVID-19 group (P = 0.040). The screening process did not significantly increase the time interval to classification and admission for immediate surgery.The time interval to surgery initiation was longer in the COVID-19 period due to the increased time interval in the semi-elective surgery group (P < 0.001). @*Conclusion@#We proposed a clinical pathway for the preoperative screening of COVID-19 in patients requiring emergency brain surgery. No significant differences were observed in the clinical outcomes before and after the COVID-19 pandemic. The protocol we described showed acceptable results during this pandemic.

Comparison of Postoperative SurgicalSite Infection and Symptomatic Intracranial Hemorrhage between Staged and Simultaneous Cranioplasty with Ventriculoperitoneal Shunt Placement: A Meta-Analysis / 대한신경손상학회지

Objective@#Consensus about the sequence of cranioplasty and ventriculoperitoneal shunt placement to reduce postoperative complications has not been established. This meta-analysis investigated and collated further evidence to determine whether staged cranioplasty with ventriculoperitoneal shunt placement would significantly reduce the risk of postoperative surgical-site infection (SSI) and symptomatic intracranial hemorrhage. @*Methods@#Two independent reviewers identified articles and extracted the data of patients who underwent cranioplasty and ventriculoperitoneal shunt placement from PubMed, Embase, and Cochrane Central Register of Controlled Trials. A random effects model was used to compare the complication rates using odd ratios (ORs) and 95% confidence intervals (CIs). A meta-regression analysis for traumatic brain injury (TBI) was additionally performed. @*Results@#Data from 7 studies with 391 patients were consecutively included. The metaanalysis revealed that staged surgery was significantly associated with lower rates of SSI after decompressive craniectomy (staged group vs. simultaneous group: 6.2% vs. 23.7%, OR:2.72, 95% CI: 1.46–5.06, I 2 =2.4%, p=0.407). Pooled analysis did not indicate a statistically significant difference between the 2 groups for symptomatic intracranial hemorrhage (staged group vs. simultaneous group: 10.4% vs. 23.0%, OR: 1.66, 95% CI: 0.74–3.73, I2 =0.0%, p=0.407). The meta-regression analysis did not indicate any modifying effect of TBI on postoperative SSI development (p=0.987). @*Conclusion@#This meta-analysis indicated that staged surgery is significantly associated with a lower rate of postoperative SSI as compared with simultaneous surgery, but there is no difference in symptomatic intracranial hemorrhage. Additionally, there is no modifying effect of TBI on SSI.

Relationship between Increased Intracranial Pressure and Mastoid Effusion

Objective@#: This study aimed to assess the relationship between increased intracranial pressure (ICP) and mastoid effusions (ME). @*Methods@#: Between January 2015 and October 2018, patients who underwent intracranial surgery and had ICP monitoring catheters placed were enrolled. ICP was recorded hourly for at least 3 days. ME was determined by the emergence of opacification in mastoid air cells on follow-up brain imaging. C-reactive protein (CRP) levels, presence of endotracheal tube (ETT) and nasogastric tube (NGT), duration of intensive care unit (ICU) stay, duration of mechanical ventilator application, diagnosis, surgical modalities, and presence of sinusitis were recorded. Each factor’s effect on the occurrence of ME was analyzed by binary logistic regression analyses. To analyze the independent effects of ICP as a predictor of ME a multivariable logistic regression analysis was performed. @*Results@#: Total of 61 (53%) out of 115 patients had ME. Among the patients who had unilateral brain lesions, 94% of subject (43/50) revealed the ipsilateral development of ME. ME developed at a mean of 11.1±6.2 days. The variables including mean ICP, peak ICP, age, trauma, CRP, ICU stays, application of mechanical ventilators and presence of ETT and NGT showed statistically significant difference between ME groups and non-ME groups in univariate analysis. Sex and the occurrence of sinusitis did not differ between two groups. Adding the ICP variables significantly improved the prediction of ME in multivariable logistic regression analysis. @*Conclusion@#: While multiple factors affect ME, this study demonstrates that ICP and ME are probably related. Further studies are needed to determine the mechanistic relationship between ICP and middle ear pressure.

Arachnoid Plasty to Prevent and Reduce Chronic Subdural Hematoma after Clipping Surgery for Unruptured Intracranial Aneurysm : A Meta-Analysis

Objective@#: Recent studies have reported that arachnoid plasty (ARP) using gelatin sponges with fibrin glue reduced the occurrence of chronic subdural hematoma (CSDH) following clipping surgery for unruptured intracranial aneurysm (UIA). This metaanalysis was conducted to collate further evidence for the efficacy of ARP in preventing postoperative CSDH. @*Methods@#: Data of patients who underwent clipping surgery were extracted from PubMed, EMBASE, and Cochrane Central Register of Controlled Trials by two independent reviewers. A random effects model was used to investigate the efficacy of ARP by using odd ratios (ORs) and 95% confidence intervals (CIs). A meta-regression analysis for male sex was additionally preformed. @*Results@#: Data from six studies with 1715 patients were consecutively included. Meta-analysis revealed that ARP was significantly associated with lower rates of CSDH development after surgical clipping for UIA (ARP group vs. control group : 3.2% vs. 7.2%; OR, 0.40; 95% CI, 0.18–0.93; I2 =44.3%; p=0.110). Meta-regression analysis did not highlight any modifying effect of the male sex on postoperative CSDH development (p=0.951). @*Conclusion@#: This meta-analysis indicated that ARP reduced the incidence rates of CSDH following clipping surgery for UIA. If feasible, ARP would be implemented as an additional surgical technique to prevent postoperative CSDH development during surgical clipping of UIA.

Skull Factors Affecting Outcomes of Magnetic Resonance-Guided Focused Ultrasound for Patients with Essential Tremor

PURPOSE: Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy has become a standard treatment for medically intractable essential tremor (ET). Skull density ratio (SDR) and skull volume in patients with ET are currently considered useful indicators of the successful application of MRgFUS. We compared the clinical outcomes of MRgFUS thalamotomy with SDR above 0.4 and 0.45. We also described patterns of SDR and skull volume in Korean patients with ET who were eligible to be screened for MRgFUS. MATERIALS AND METHODS: In screening 318 ET patients, we evaluated patterns of skull density and skull volume according to age and sex. Fifty patients with ET were treated with MRgFUS. We investigated the effects of SDR and skull volume on treatment parameters and the outcomes of ET. RESULTS: The mean SDR of the 318 ET patients was 0.45±0.11, and that for skull volume was 315.74±40.95 cm³. The male patients had a higher SDR than female patients (p=0.047). Skull volume significantly decreased with aging. SDR and skull volume exhibited a linear negative relationship. Among therapeutic parameters, maximal temperature was positively related to SDR, while sonication number was not related to either SDR or skull volume. Tremor outcome was also not related to SDR or skull volume. CONCLUSION: SDR varied widely from 0.11 to 0.73, and men had a higher SDR. Therapeutic parameters and clinical outcomes were not affected by SDR or skull volume.

MRI Assessment of Cerebral Small Vessel Disease in Patients with Spontaneous Intracerebral Hemorrhage

PURPOSE: Cerebral small vessel disease (SVD) is known to be associated with ischemic stroke, intracerebral hemorrhage (ICH), and cognitive impairment. In this retrospective observational study, we explored SVD markers on MRI relevant to spontaneous ICH. MATERIALS AND METHODS: The ICH group consisted of 150 consecutive patients with a first primary parenchymal ICH, and the control group consisted of 271 age- and sex-matched individuals who underwent brain MRI in a health care center. We compared cerebral microbleeds (CMBs), white matter hyperintensities (WMHs), enlarged perivascular space (EPVS), and lacunae in the ICH and control groups. RESULTS: A total of 1278 CMB lesions were identified in 121 of the 150 patients in the ICH group (80.6%), while 77 CMB lesions were found in 32 of the 271 individuals in the control group (11.8%). WMH and EPVS were more severe and lacunae were more frequent in the ICH patients than in the control group. When receiver operating characteristic (ROC) curves were plotted, number of CMBs most significantly predicted ICH. All imaging markers were significantly associated with ICH in every age group. The location of CMBs coincided with the location of ICH, and ICH volume correlated with CMB count. CONCLUSION: All MRI markers for SVD were worse in ICH patients than in healthy controls, and these markers were prominent even in young ICH patients. Lacunae, WMH, EPVS, and CMB should be considered as factors related with spontaneous ICH.

Rupture of a Middle Meningeal Artery Pseudoaneurysm in Moyamoya Syndrome Related with Tuberculous Meningitis

We report a rare case of a patient with Moyamoya syndrome who presented with intracerebral hemorrhage resulting from rupture of a middle meningeal artery pseudoaneurysm. This 38-year-old woman was unconscious and hemiplegic when she was admitted to our hospital. The patient had mental retardation as a result of tuberculous meningitis infection at the age of one year. On radiologic examination, she had intracerebral hemorrhage in the right temporo-parietal lobe and an aneurysm in the middle meningeal artery with right internal carotid artery occlusion. The patient underwent surgical treatment for the hemorrhage and aneurysm. The radiologic data, intraoperative findings, and pathology were consistent with a diagnosis of pseudoaneurysm. In the current report, we describe a rare case of a patient with a history of tuberculous meningitis who developed Moyamoya syndrome and pseudoaneurysm, which resulted in a ruptured middle meningeal artery pseudoaneurysm and brain hemorrhage.

A Case of Coincidental Intrasellar Chordoma and Pituitary Adenoma

Although chordomas are midline tumors, primarily intrasellar chordomas are extremely rare. In this report, the authors describe the case of a 68-year-old female with partial abducens nerve palsy in the right eye due to the intrasellar cystic tumor. After endonasal trans-sphenoidal surgery, intraoperative and histopathological findings confirmed the co-occurrence of an entirely intrasellar chordoma and pituitary adenoma. To our knowledge, the present case is the third reported case of an intrasellar chordoma with a pituitary adenoma.

An Unruptured Anterior Communicating Artery Aneurysm Presenting with Left Homonymous Hemianopsia: A Case Report

Unruptured cerebral aneurysms sometimes present with visual symptomsdue to compression of the visual pathways. However, until now, unruptured anterior communicating artery (ACoA) aneurysms presenting visual field defects have been extremely rare. The authors report the case of a 51-year-old woman who presented with left homonymous hemianopsia. Radiological findings demonstrated an ACoA aneurysm filled with thrombus, that was compressing the optic chiasm and post-chiasmal tract. The patient underwent clipping of the aneurysm, which resolved the visual field defect. In cases of visual field defects, an ACoA aneurysm should be included in the differential diagnosis.

Retrograde Suction Decompression with an Inahara Carotid Shunt for Clipping a Large Distal Internal Carotid Artery Aneurysm

We describe a technique to clip a large internal carotid artery (ICA) aneurysm via a retrograde suction decompression (RSD). A large aneurysm in the right distal ICA involving the bifurcation region measuring 1.2×1.1×0.7 cm with posterior projection was managed with assisted RSD technique. The anterior choroidal artery emerged from the side wall of the aneurysm. An Inahara shunt was inserted into the ICA with neck dissection, and RSD was applied after completely clipping the aneurysm. RSD with an Inahara carotid shunt is useful for complete visualization of the aneurysm, including its surrounding structures, and for proximal control of the parent vessels, subsequently achieving satisfactory clip placement.

Use of Three-Dimensional Curved-Multiplanar Reconstruction Images for Sylvian Dissection in Microsurgery of Middle Cerebral Artery Aneurysms

PURPOSE: The purpose of this study was to introduce a method of using three-dimensional (3D) curved-multiplanar reconstruction (MPR) images for sylvian dissection during microsurgical treatment of middle cerebral artery (MCA) aneurysms. MATERIALS AND METHODS: Forty-nine patients who had undergone surgery for MCA aneurysms were enrolled. We obtained the 3D curved-MPR images along the sphenoid ridge using OsiriX MD™ imaging software, compared sylvian dissection time according to several 3D MPR image factors, and investigated the correlations between these images and intraoperative findings. RESULTS: Utilizing preoperative information of the sylvian fissure (SF) and peri-aneurysmal space on 3D curved-MPR images, we could predict the feasibility of sylvian dissection for a safe surgery. 3D curved-MPR images showed several features: first, perpendicular images to the sylvian surface in the same orientation as the surgeon's view; second, simultaneous visualization of the brain cortex, vessels, and cisternal space; and third, more accurate measurement of various parameters, such as depth of the MCA from the sylvian surface and the location and width of the SFs. CONCLUSION: In addition to conventional image studies, 3D curved-MPR images seem to provide useful information for Sylvian dissection in the microsurgical treatment of MCA aneurysms.

Brain Abscesses Associated with Asymptomatic Pulmonary Arteriovenous Fistulas

Brain abscess commonly occurs secondary to an adjacent infection (mostly in the middle ear or paranasal sinuses) or due to hematogenous spread from a distant infection or trauma. Pulmonary arteriovenous fistulas (AVFs) are abnormal direct communications between the pulmonary artery and vein. We present two cases of brain abscess associated with asymptomatic pulmonary AVF. A 65-year-old woman was admitted with a headache and cognitive impairment that aggravated 10 days prior. An magnetic resonance (MR) imaging revealed a brain abscess with severe edema in the right frontal lobe. We performed a craniotomy and abscess removal. Bacteriological culture proved negative. Her chest computed tomography (CT) showed multiple AVFs. Therapeutic embolization of multiple pulmonary AVFs was performed and antibiotics were administered for 8 weeks. A 45-year-old woman presented with a 7-day history of progressive left hemiparesis. She had no remarkable past medical history or family history. On admission, blood examination showed a white blood cell count of 6290 cells/uL and a high sensitive C-reactive protein of 2.62 mg/L. CT and MR imaging with MR spectroscopy revealed an enhancing lesion involving the right motor and sensory cortex with marked perilesional edema that suggested a brain abscess. A chest CT revealed a pulmonary AVF in the right upper lung. The pulmonary AVF was obliterated with embolization. There needs to consider pulmonary AVF as an etiology of cerebral abscess when routine investigations fail to detect a source.

The Prevalence of Undiagnosed Presurgical Cognitive Impairment and Its Postsurgical Clinical Impact in Older Patients Undergoing Lumbar Spine Surgery

OBJECTIVE: Because elderly patients are undergoing more surgeries, the importance of postoperative cognitive impairment (CI) evaluations is rising, especially for spine surgery, which is related to subjective pain. We investigated the prevalence of undiagnosed CI among elderly patients who underwent spine surgery and the impact of CI on postoperative outcomes. METHODS: The preoperative cognitive statuses of 129 patients over 65 who underwent lumbar spine surgery from 2012 to 2014 were determined with the Mini-Mental State Examination, and patients with scores under 24 were diagnosed with CI. The patients were then divided into a CI group (n=49) and non-cognitive impairment (NCI) group (n=80). RESULTS: Among the 129 patients, 49 (38.0%) were diagnosed with CI, and 9 (7.0%) had severe CI. The age of the CI group (72.88±6.20 years) was significantly greater than that of the NCI group (69.96±4.53 years). In contrast, the postoperative visual analog scale scores and performance statuses did not differ significantly. However, postoperative delirium was more frequent and the hospital stay length was longer in the CI group compared with the NCI group (p<0.05). CONCLUSION: A high prevalence of undiagnosed CI was discovered among elderly patients undergoing spine surgery. The existence of CI was associated with higher rates of postoperative delirium and prolonged hospital stays, which affected clinical outcomes. Thus, CI assessments should be included in preoperative evaluations of elderly patients prior to spine surgery.

A Case of Traumatic Unilateral Internuclear Ophthalmoplegia: Clinical Significance of Susceptibility-Weighted Imaging / 대한신경손상학회지

A 43-year-old man was admitted for head trauma after falling backward. The patient complained of diplopia. Unilateral internuclear ophthalmoplegia (INO) was diagnosed during the neurologic examination. Initially, no specific finding was shown on T2-weighted, T1-weighted, and fluid attenuated inversion recovery brain magnetic resonance image (MRI) or brain computed tomography (CT). However, susceptibility-weighted imaging (SWI) definitively demonstrated a tiny hemorrhage at the midline of the pontomesencephalic junction. The patient's symptom improved after 12 weeks. We discuss the clinical significance of SWI when traumatic INO due to a tiny hemorrhage is suspected.

Acute Contralateral Radiculopathy after Unilateral Transforaminal Lumbar Interbody Fusion

OBJECTIVE: Cases of contralateral radiculopathy after a transforaminal lumbar interbody fusion with a single cage (unilateral TLIF) had been reported, but the phenomenon has not been explained satisfactorily. The purpose of this study was to determine its incidence, causes, and risk factors. METHODS: We did retrospective study with 546 patients who underwent a unilateral TLIF, and used CT and MRI to study the causes of contralateral radicular symptoms that appeared within a week postoperatively. Clinical and radiological results were compared by dividing the patients into the symptomatic group and asymptomatic group. RESULTS: Contralateral symptoms occurred in 32 (5.9%) of the patients underwent unilateral TLIF. The most common cause of contralateral symptoms was a contralateral foraminal stenosis in 22 (68.8%), screw malposition in 4 (12.5%), newly developed herniated nucleus pulposus in 3 (9.3%), hematoma in 1 (3.1%), and unknown origin in 2 patients (6.3%). 16 (50.0%) of the 32 patients received revision surgery. There was no difference in visual analogue scale and Oswestry disability index between the two groups at discharge. Both preoperative and postoperative contralateral foraminal areas were significantly smaller, and postoperative segmental angle was significantly greater in the symptomatic group comparing to those of the asymptomatic group (p<0.05). CONCLUSION: The incidence rate is not likely to be small (5.9%). If unilateral TLIF is performed for cases when preoperative contralateral foraminal stenosis already exists or when a large restoration of segmental lordosis is required, the probability of developing contralateral radiculopathy is increased and caution from the surgeon is needed.

The Effects of Spinopelvic Parameters and Paraspinal Muscle Degeneration on S1 Screw Loosening

OBJECTIVE: To investigate risk factors for S1 screw loosening after lumbosacral fusion, including spinopelvic parameters and paraspinal muscles. METHODS: We studied with 156 patients with degenerative lumbar disease who underwent lumbosacral interbody fusion and pedicle screw fixation including the level of L5-S1 between 2005 and 2012. The patients were divided into loosening and non-loosening groups. Screw loosening was defined as a halo sign larger than 1 mm around a screw. We checked cross sectional area of paraspinal muscles, mean signal intensity of the muscles on T2 weight MRI as a degree of fatty degeneration, spinopelvic parameters, bone mineral density, number of fusion level, and the characteristic of S1 screw. RESULTS: Twenty seven patients showed S1 screw loosening, which is 24.4% of total. The mean duration for S1 screw loosening was 7.3+/-4.1 months after surgery. Statistically significant risk factors were increased age, poor BMD, 3 or more fusion levels (p<0.05). Among spinopelvic parameters, a high pelvic incidence (p<0.01), a greater difference between pelvic incidence and lumbar lordotic angle preoperatively (p<0.01) and postoperatively (p<0.05). Smaller cross-sectional area and high T2 signal intensity in both multifidus and erector spinae muscles were also significant muscular risk factors (p<0.05). Small converging angle (p<0.001) and short intraosseous length (p<0.05) of S1 screw were significant screw related risk factors (p<0.05). CONCLUSION: In addition to well known risk factors, spinopelvic parameters and the degeneration of paraspinal muscles also showed significant effects on the S1 screw loosening.