Brain Activation Evoked by Sensory Stimulation in Patients with Spinal Cord Injury : Functional Magnetic Resonance Imaging Correlations with Clinical Features

OBJECTIVE: The purpose of this study is to determine whether the changes of contralateral sensorimotor cortical activation on functional magnetic resonance imaging (fMRI) can predict the neurological outcome among spinal cord injury (SCI) patients when the great toes are stimulated without notice. METHODS: This study enrolled a total of 49 patients with SCI and investigated each patient's preoperative fMRI, postoperative fMRI, American Spinal Injury Association (ASIA) score, and neuropathic pain occurrence. Patients were classified into 3 groups according to the change of blood oxygenation level dependent (BOLD) response on perioperative fMRI during proprioceptive stimulation with repetitive passive toe movements : 1) patients with a response of contralateral sensorimotor cortical activation in fMRI were categorized; 2) patients with a response in other regions; and 3) patients with no response. Correlation between the result of fMRI and each parameter was analyzed. RESULTS: In fMRI data, ASIA score was likely to show greater improvement in patients in group A compared to those belonging to group B or C (p<0.001). No statistical significance was observed between the result of fMRI and neuropathic pain (p=0.709). However, increase in neuropathic pain in response to the signal change of the ipsilateral frontal lobe on fMRI was statistically significant (p=0.030). CONCLUSION: When there was change of BOLD response at the contralateral sensorimotor cortex on perioperative fMRI after surgery, relief of neurological symptoms was highly likely for traumatic SCI patients. In addition, development of neuropathic pain was likely to occur when there was change of BOLD response at ipsilateral frontal lobe.

Grisel's Syndrome Induced by Mycobacterium tuberculosis

Grisel's syndrome is a non-traumatic subluxation of the atlantoaxial joints, which is caused by an inflammatory process in the upper neck. It is rare to find literary reports of Grisel's syndrome with an evident pathogen in a lesion. For the first time in Korea, we report a 36-year-old female with Grisel's syndrome having an atlantoaxial subluxation, which was caused by a retropharyngeal abscess secondary to pulmonary Mycobacterium tuberculosis. The patient was treated with an anti-tuberculosis regimen and was prescribed a Philadelphia collar for the control of torticollis. The result of magnetic resonance imaging (MRI) showed an improved atlantoaxial alignment, after drug treatment and immobilization. This patient was neurologically intact and free from symptomatic complaints at follow-up visit. Dynamic cervical radiograph confirmed that the atlantoaxial joints had been stable. The pathophysiology of Grisel's syndrome, along with anatomical attributes, was explained on the basis of the patient's clinical course.

Superficial Siderosis in Central Nervous System: A Case Report and Literature Review / 대한신경손상학회지

Superficial siderosis (SS) in central nervous system is a rare, slowly progressive disease and usually misdiagnosed or diagnosed too late when the patient is chronically devastated. A 55-year-old man with deafness and gait disturbance for ten years was referred from otorhinologist for evaluation of brain. Magnetic resonance image (MRI) showed symmetric hypointense rim partially delineated the bilateral hemisphere on gradient-recalled-echo T2-weighted image, and it was diagnosed as hemosiderin deposition in subarachnoid and subpial meningeal layer. The correct diagnosis of cerebral superficial siderosis can be achieved by careful neurological examination and MRI because computed tomography findings and symptoms are ambiguous. Serial follow-up of imaging study and education for patient are necessary to prevent progression of SS.

Superficial Siderosis in Central Nervous System: A Case Report and Literature Review / 대한신경손상학회지

Superficial siderosis (SS) in central nervous system is a rare, slowly progressive disease and usually misdiagnosed or diagnosed too late when the patient is chronically devastated. A 55-year-old man with deafness and gait disturbance for ten years was referred from otorhinologist for evaluation of brain. Magnetic resonance image (MRI) showed symmetric hypointense rim partially delineated the bilateral hemisphere on gradient-recalled-echo T2-weighted image, and it was diagnosed as hemosiderin deposition in subarachnoid and subpial meningeal layer. The correct diagnosis of cerebral superficial siderosis can be achieved by careful neurological examination and MRI because computed tomography findings and symptoms are ambiguous. Serial follow-up of imaging study and education for patient are necessary to prevent progression of SS.

Interobserver and Intraobserver Reliability of Sub-Axial Injury Classification and Severity Scale between Radiologist, Resident and Spine Surgeon

OBJECTIVE: The sub-axial injury classification (SLIC) and severity scale was developed to decide whether to operate the cervical injured patient or not, but the reliability of SLIC and severity scale among the different physicians was not well known. Therefore, we evaluated the reliability of SLIC among a spine surgeon, a resident of neurosurgery and a neuro-radiologist. METHODS: In retrograde review in single hospital from 2002 to 2009 years, 75 cases of sub-axial spine injured patients underwent operation. Each case was blindly reviewed for the SLIC and severity scale by 3 different observers by two times with 4 weeks interval with randomly allocated. The compared axis was the injury morphology score, the disco-ligamentous complex score, the neurological status score and total SLIC score; the neurological status score was derived from the review of medical record. The kappa value was used for the statistical analysis. RESULTS: Interobserver agreement of SLIC and severity scale was substantial agreement in the score of injury morphology [intraclass correlation (ICC)=0.603] and total SLIC and severity sacle (ICC value=0.775), but was fair agreement in the disco-ligamentous complex score (ICC value=0.304). Intraobserver agreements were almost perfect agreement in whole scales with ICC of 0.974 in a spine surgeon, 0.948 in a resident of neurosurgery, and 0.963 in a neuro-radiologist. CONCLUSION: The SLIC and severity scale is comprehensive and easily applicable tool in spine injured patient. Moreover, it is very useful tool to communicate among spine surgeons, residents of neurosurgery and neuro-radiologists with sufficient reproducibility.

Radiological Efficacy of Cervical Lateral Mass Screw Insertion and Rod Fixation by Modified Magerl's Method (Yoon's Method) with Minimum 2 Years of Follow-up

OBJECTIVE: Cervical lateral mass screw insertion and rod fixation is a useful method for stabilizing the cervical disease, so various modified techniques were present. Many surgeons had reported the biomechanical safety according to the screw positioning method in the cervical spine, but the modified Magerl's method (Yoon's method) was not well studied. So, this study assessed the radiological efficacy of the modified Magerl's method with long-term follow-up. METHODS: This study retrospectively reviewed 323 lateral mass screws of 50 patients who had followed-up at least 2 years. Radiologic data were analyzed as parameters of complications after operation, including kyphotic or lordotic change, bone fusion, pull-out or malposition of screw, foraminal stenosis, adjacent disc degeneration or aggravation, pseudoarthrosis, and vertebral artery injury. RESULTS: The mean follow-up period was 32 (24 to 52) months. There were kyphotic changes in 4.0%(2 of 50 cases). Unsuccessful bone fusion occurred in 4.0%(2 of 50 cases). Among the 323 screws, screw pull-out (4.0%. 2 of 50cases, 3 of 323 screws), foraminal invasion (1.2% of total screws), and facet injury (0.6% of total screws) occurred. CONCLUSION: The lateral mass screw insertion and rod fixation by the modified Magerl's method (Yoon's method) is a safe and reliable technique with low rate of complication related to instruments in minimum 2 years follow-up.

Lumbar Disc Screening Using Back Pain Questionnaires: Oswestry Low Back Pain Score, Aberdeen Low Back Pain Scale, and Acute Low Back Pain Screening Questionnaire

OBJECTIVE: To evaluate the usefulness of back pain questionnaires for lumbar disc screening among Korean young males. METHODS: We carried out a survey for lumbar disc screening through back pain questionnaires among the volunteers with or without back pain. Three types of back pain questionnaire (Oswestry Low Back Pain Score, Aberdeen Low Back Pain Scale, and Acute Low Back Pain Screeing Questionnaire) were randomly assigned to the examinees. The authors reviewed lumbar imaging studies (simple lumbar radiographs, lumbar computed tomography, and magnetic resolutional images), and the severity of lumbar disc herniation was categorized according to the guidelines issued by the Korean military directorate. We calculated the relationship between the back pain questionnaire scores and the severity of lumbar disc herniation. RESULTS: The scores of back pain questionnaires increased according to the severity of lumbar disc herniation. But, the range of scores was very vague, so it is less predictable to detect lumbar disc herniation using only back pain questionnaires. The sensitivity between the back pain questionnaires and the presence of lumbar disc herniation was low (16-64%). CONCLUSION: Screening of lumbar disc herniation using only back pain questionnaires has limited value.

Prevalence of Lumbar Disc Herniation in Adolescent Males in Seoul, Korea: Prevalence of Adolescent LDH in Seoul, Korea

OBJECTIVE: The authors surveyed the prevalence and the clinical character of lumbar disc herniation (LDH) in Korean male adolescents, and the usefulness of current conscription criteria. METHODS: The data of 39,673 nineteen-year-old males that underwent a conscription examination at the Seoul Regional Korean Military Manpower Administration (MMA) from October 2010 to May 2011 were investigated. For those diagnosed as having lumbar disc herniation, prevalences, subject characteristics, herniation severities, levels of herniation, and modified Korean Oswestry low back pain disability scores by MMA physical grade were evaluated. The analysis was performed using medical certificates, medical records, medical images, and electromyographic and radiologic findings. RESULTS: The prevalence of adolescent LDH was 0.60%(237 of the 39,673 study subjects), and the prevalence of serious adolescent LDH with thecal sac compression or significant discogenic spinal stenosis was 0.28%(110 of the 39,673 study subjects). Of the 237 adolescent LDH cases, 105 (44.3%) were of single level LDH and 132 (55.7%) were of multiple level LDH, and the L4-5 level was the most severely and frequently affected. Oswestry back pain disability scores increased with herniation severity (p<0.01), and were well correlated with MMA grade. CONCLUSIONS: In this large cohort of 19-year-old Korean males, the prevalence of adolescent LDH was 0.60% and the prevalence of serious adolescent LDH, which requires management, was relatively high at 0.28%. MMA physical grade was confirmed to be a useful measure of the disability caused by LDH.

Prevalence and Insight of Scoliosis among Korean Male Adolescents by Chest Radiographs

OBJECTIVE: We applied chest radiographs to scoliosis screening for conscription. Prevalence, types of scoliosis, and insight of examinees with scoliosis were investigated. METHODS: In this study, chest radiographs of 2417 males, who had been given an examination for conscription at the Seoul Regional Military Manpower Administration from April 2009 to May 2009, were analyzed. The prevalence of scoliosis more than a 10 degrees Cobb angle was calculated. The insight of scoliosis was investigated in every examinee and thoracolumbar radiographs were checked in those examinees with more than a 20 degree Cobb angle. RESULTS: Among 1904 males, 477 (19.7%) exhibited scoliosis involving more than a 5 degrees Cobb angle were and 131 (5.4%) exhibitedmore than a 10 degree Cobb angle. In those 131 cases, 18 (13.7%) had a known history of problems with scoliosis. Among the group measuring less than a 10 degree Cobb angle, 1.7% of them misunderstood scoliosis. Insight of scoliosis increased according to the severity of spinal curvature; however, nearly half of the cases with a 20 degree or greater Cobb angle had no insight with respect to their scoliosis. CONCLUSION: In male adolescents, the prevalence of scoliosis with a greater than 10 degree Cobb angle was 5.4% and there was a low insight with respect to scoliosis.

Preliminary Efficacy of Combination Decompressive Surgery, Stabilization and Cyberknife Radiosurgery: A New Treatment Paradigm for Metastatic Spinal Tumors with Cord Invasion

OBJECTIVE: The goal of this retrospective study was to assess clinical and radiographic outcomes of posterior surgical decompression with stabilization followed by image-guided robot Cyberknife radiosurgery for encircling malignant tumors of the spine. METHODS: From August 2008 to December 2009, 14 consecutive patients with a malignant spinal metastatic lesion with cord compression were treated at the author's institute. Patients underwent on a decompressive surgery by the posterior approach, and latent unstable spines were stabilized with instrumentation. After recovery, radiosurgery was administered at doses ranging from 16 to 26 Gy (mean 20.1Gy) prescribed to the 75-85% isodose line that encompassed at least 95% of tumor volumes. Visual Analogue Scale, American spine injury association grades, and MRI with gadolinium enhancement were used to monitor pain, neurology, and radiological outcomes, respectively, after the radiosurgery. RESULTS: No acute radiation-induced toxicity or new neurological deficit occurred during the follow-up period (mean 4.5 months). Axial pain improved in 10 out of the 14 patients. No hardware failure was encountered. At 3-6 months after the Cyberknife radiosurgery, local control and effective therapeutic rates were both 80%(8/10) and no lesion enhancement on vertebral bodies or pedicles was visualized by MRI. CONCLUSION: Posterior decompression with stabilization followed by radiosurgery of residual tumor in the anterolateral region is useful in cases where an anterior approach or a circumferential approach is not an option due to medical condition. Longer term follow-up is required to evaluate survival and late toxicities.

Metronidazole Induced Encephalopathy in a Patient with Brain Abscess

Metronidazole is commonly used for brain abscess but is not well known for its neurotoxic complications. Metronidazole-induced encephalopathy (MIEP) is toxic encephalopathy associated with the use of metronidazole. We experienced a case of brain abscess which developed reversible severe MIEP during treatment period. Although MIEP occurs in typical locations, it is not easy to differentiate from other conditions such as cerebral infarction, demyelinating diseases and metabolic diseases. Neurosurgeons should be aware that severe MIEP can occur during the use of metronidazole though it is not common.

Comparison of Bony Fusion Between the Hollow Cage Group and the Cage with Bone Substitutes Group in One-level Cervical Spinal Disorders

OBJECTIVE: The aim of this study was to assess the clinical outcomes and bone fusion rates after insertion of hollow cages or cages with bone substitutes for treatment of disc protrusion in the cervical spine. METHODS: We performed a retrospective review of 93 patients who had undergone cage-assisted anterior cervical spine fusion. Patients were treated with hollow cages (N=52) or with cages with bone substitutes (N=41). Initial and follow up radiologic data were analyzed using Vavruch bone fusion criteria. RESULTS: Clinical outcomes including preoperative and postoperative pain and functional scores were not significantly different between the two patient groups. The over-all fusion rates differed between the two groups: patients treated with hollow cages demonstrated an average fusion rate of 84.6%, while patients treated with cages with bone substitutes demonstrated an average fusion rate of 87.8%, but these differences were not significant 24 months after surgery. At 18 months after surgery, the fusion rates of patients treated with cages with bone substitutes were significantly different from those of patients treated with hollow cages. Among patients who received bone substitutes, patients who received DBM exhibited better fusion outcomes than patients treated with other bone materials after 18 months of follow-up. CONCLUSION: Patients who are surgically treated with anterior cervical spine fusion for disc protrusion using cages with bone substitutes may achieve earlier fusion than patients treated with hollow cages, although both groups show similar final fusion rates.

Comparative Study of Outcomes between Shunting after Cranioplasty and in Cranioplasty after Shunting in Large Concave Flaccid Cranial Defect with Hydrocephalus

OBJECTIVE: The cranioplasty and ventriculoperitoneal (VP) shunt operation have been used to treat a large cranial defect with posttraumatic hydrocephalus (PTH). The aim of this study was to evlauate the difference of outcomes between in the shunting after the cranioplasty (group 1) and the cranioplasty after the shunting (group 2) in a large flaccid cranial defect with PTH. METHODS: In this study, a retrospective review was done on 23 patients undergoing the cranioplasty and VP shunt operation after the decompressive craniectomy for a refractory intracranial hypertension from 2002 to 2005. All of 23 cases had a large flaccid concave cranial defect and PTH. Ten cases belong to group 1 and 13 cases to group 2. The outcomes after operations were compared in two groups 6 months later. RESULTS: The improvement of Glasgow outcome scale (GOS) was seen in 8 cases (80.0%) of total 10 cases in group 1, and 6 cases (46.2%) of 13 cases in group 2. Three (75.0%) of 4 cases with hemiparesis in group 1 and 3 of 6 cases (50.0%) in group 2 were improved. All cases (2 cases) with decrease of visual acuity were improved in each group. Dysphasia was improved in 3 of 5 cases (60%) in group 1 and 4 of 6 cases (66.6%) in group 2. CONCLUSION: These results suggest that outcomes in group 1 may be better than in group 2 for a large flaccid concave cranial defect with PTH.

Time Course of Symptom Disappearance after Microvascular Decompression for Hemifacial Spasm

OBJECTIVE: This study is to investigate time course of symptom disappearance in patients whose spasm relieved completely after microvascular decompression (MVD). METHODS: Of 115 patients with hemifacial spasm (HFS) who underwent MVD from April 2003 to December 2006, 89 patients who had no facial paralysis after operation and showed no spasm at last follow-up more than 1.5 years after operation were selected. Symptom disappearance with time after MVD was classified into type 1 (symptom disappearance right after operation), type 2 (delayed symptom disappearance) and type 3 (unusual symptom disappearance). Type 2 was classified into type 2a (with postoperative silent period) and type 2b (without silent period). RESULTS: Type 1, type 2a, type 2b and type 3 were 38.2%, 48.37%, 12.4% and 1.1%, respectively. Delayed disappearance group (type 2) was 60.7%. Post-operative symptom duration in all cases ranged from 0 to 900 days, average was 74.6 days and median was 14 days. In case of type 2, average post-operative symptom duration was 115.1 days and median was 42 days. Five and 3 patients required more than 1 year and 2 years, respectively, until complete disappearance of spasm. In type 2a, postoperative silent period ranged from 1 to 10 days, with an average of 2.4 days. CONCLUSION: Surgeons should be aware that delayed symptom disappearance after MVD for HFS is more common than it has been reported, silent period can be as long as 10 days and time course of symptom disappearance is various as well as unpredictable.

Technical Modification and Comparison of Results with Hirabayashi's Open-door Laminoplasty

OBJECTIVE: Hirabayashi's open-door laminoplasty is a good procedure to use to treat patients with myelopathy of the cervical spine; however, the authors have experienced problems in maintaining an open-window in cervical spines after the surgery. The authors developed a modified method of the expanded open-door laminoplasty and compared the radiological and clinical results with those of the classical method. METHODS: In the modified method, wiring fixation with lateral mass screws on the contra lateral-side instead of fixing the paraspinal muscle or facet joint, as in the classical methods, was used in the open window of the cervical spine. Fifteen patients with cervical myelopathy were treated using the classical method and 12 patients were treated using the modified method. Preoperative and postoperative clinical conditions were assessed according to the Japanese Orthopedic Association (JOA) score. The radiological results were compared with the preoperative and postoperative computed tomography (CT) findings. RESULTS: In both methods, the clinical results revealed a significant improvement in neurological function (p<0.001). Image analysis revealed that the cervical canals were continuously expanded in patients treated using the modified methods. However, authors have observed restenosis during the follow-up periods in 4 patients treated using the original method. Progression to deformity and spinal instability were not observed in any of the patients in the radiological results. CONCLUSION: Although analysis with a larger population and a longer follow-up period needs to be undertaken, our modified open-door laminoplasty has shown an advantage in better maintaining an open window in comparison with the Hirabayashi's open-door laminoplasty.

Technical Modification and Comparison of Results with Hirabayashi's Open-door Laminoplasty

OBJECTIVE: Hirabayashi's open-door laminoplasty is a good procedure to use to treat patients with myelopathy of the cervical spine; however, the authors have experienced problems in maintaining an open-window in cervical spines after the surgery. The authors developed a modified method of the expanded open-door laminoplasty and compared the radiological and clinical results with those of the classical method. METHODS: In the modified method, wiring fixation with lateral mass screws on the contra lateral-side instead of fixing the paraspinal muscle or facet joint, as in the classical methods, was used in the open window of the cervical spine. Fifteen patients with cervical myelopathy were treated using the classical method and 12 patients were treated using the modified method. Preoperative and postoperative clinical conditions were assessed according to the Japanese Orthopedic Association (JOA) score. The radiological results were compared with the preoperative and postoperative computed tomography (CT) findings. RESULTS: In both methods, the clinical results revealed a significant improvement in neurological function (p<0.001). Image analysis revealed that the cervical canals were continuously expanded in patients treated using the modified methods. However, authors have observed restenosis during the follow-up periods in 4 patients treated using the original method. Progression to deformity and spinal instability were not observed in any of the patients in the radiological results. CONCLUSION: Although analysis with a larger population and a longer follow-up period needs to be undertaken, our modified open-door laminoplasty has shown an advantage in better maintaining an open window in comparison with the Hirabayashi's open-door laminoplasty.

Analysis of Factors Related to Neurological Deficit in Thoracolumbar Fractures

OBJECTIVE: The purpose of this study is to determine the factors that have effects on the neurological deficit in the patients with thoracolumbar fracture. METHODS: Forty-eight patients were included. Cause of injury, type of injury, time interval, combined injury, kyphotic angle, spinal canal compromise, sagittal diameter, the most narrow sagittal diameter, transverse diameter, the most narrow transverse diameter, and remained height of vertebra body were concerned as the factors. The patients with American Spinal Injury Association(ASIA) impairment scale grade A to D were considered as having neurology while others with ASIA grade E were considered to be without neurology. The patients with ASIA grade A were classified to paraplegia group and the patients with ASIA grade B to E were not thought to be paraplegia. Statistical analysis for these groups were performed. RESULTS: Spinal canal compromise (P<0.001) have correlation with neurological deficit. The most narrow sagittal diameter was smaller in the group with deficit than that in the group without deficit (P=0.004). Also, combined injury have correlation with neurology (P=0.028). Spinal canal compromise (P<0.001), sagittal diameter (P=0.032), the most narrow sagittal diameter (P=0.025), and Denis type (P<0.001) also have correlation with paraplegia. CONCLUSION: The factors of percentage of spinal canal compromise, the most narrow sagittal diameter, and combined injury are predictive of neurological deficit. The patients with paraplegia may be predicted by the factors such as type of injury, spinal canal compromise, sagittal diameter, the most narrow sagittal diameter, and Denis type.

What are the Causative Factors for a Slow, Progressive Enlargement of a Chronic Subdural Hematoma?

PURPOSE: To test the hypothesis that chronic subdural hematoma (CSDH) enlarges by the causative factors, this study has performed. METERIALS AND METHODS: In 10 patients with CSDH, coagulation factors in venous blood taken at the time of surgery and hematomic contents aspirated from the CSDH were studied, using both laboratory assays and microscopy. RESULTS: When compared to the range of normal plasma, the hematoma fluids demonstrated a marked reduction in factor II, V, VII, VIII, and X, moderate reduction of factors IX and XI, and slight reduction of factor XII. Activated protein C and antithrombin III levels were decreased. The FDP (Fibrinogen Degradation Product) levels in chronic subdural hematoma were extremely high. The endothelial cells of the macrocapillaries (also called "sinusoid") showed numerous gap junctions between adjacent endothelial cells and a thinness or absence of the basement membrane, suggesting that the macrocapillaries are very fragile and susceptible to bleeding. CONCLUSION: Excessive coagulation in the hematoma, predominantly via the extrinsic clotting pathway, local hyperfibrinolysis, transmitted pulsations, and characteristics of the macrocapillaries play an important role in the leakage of blood and the enlargement of CSDH.

A Multi-center Clinical Study of Posterior Lumbar Interbody Fusion with the Expandable Stand-alone Cage (Tyche(R) Cage) for Degenerative Lumbar Spinal Disorders

OBJECTIVE: This multi-center clinical study was designed to determine the long-term results of patients who received a one-level posterior lumbar interbody fusion with expandable cage (Tyche(R) cage) for degenerative spinal diseases during the same period in each hospital. METHODS: Fifty-seven patients with low back pain who had a one-level posterior lumbar interbody fusion using a newly designed expandable cage were enrolled in this study at five centers from June 2003 to December 2004 and followed up for 24 months. Pain improvement was checked with a Visual Analogue Scale (VAS) and their disability was evaluated with the Oswestry Disability Index. Radiographs were obtained before and after surgery. At the final follow-up, dynamic stability, quality of bone fusion, interveretebral disc height, and lumbar lordosis were assessed. In some cases, a lumbar computed tomography scan was also obtained. RESULTS: The mean VAS score of back pain was improved from 6.44 points preoperatively to 0.44 at the final visit and the score of sciatica was reduced from 4.84 to 0.26. Also, the Oswestry Disability Index was improved from 32.62 points preoperatively to 18.25 at the final visit. The fusion rate was 92.5%. Intervertebral disc height, recorded as 9.94+/-2.69 mm before surgery was increased to 12.23+/-3.31 mm at postoperative 1 month and was stabilized at 11.43+/-2.23 mm on final visit. The segmental angle of lordosis was changed significantly from 3.54+/-3.70 degrees before surgery to 6.37+/-3.97 degrees by 24 months postoperative, and total lumbar lordosis was 20.37+/-11.30 degrees preoperatively and 24.71+/-11.70 degrees at 24 months postoperative. CONCLUSION: The re have been no special complications regarding the expandable cage during the follow-up period and the results of this study demonstrates a high fusion rate and clinical success.

Clinical and Computed Tomography Evaluation of Plate and Screw on the Cervical Lateral Mass: A Modified Magerl's Technique

OBJECTIVE: To determine the clinical and radiological safety of 15 consecutive patients managed with plate and screw fixation systems applied to the cervical lateral mass. METHODS: 15 patients who underwent posterior cervical and T1 arthrodesis were reviewed from Jan 2002 to Dec 2004. Posterior cervical screw and plate fixation was applied on the lateral mass of the cervical spine. The authors have tried lateral mass screw fixation using a modified Magerl's technique (20 degrees lateral and 20~30 degrees rostral screw trajectory) under preliminary radiological study. The average patient age was 39.73 degrees+/-11.00 years, and the average follow-up period was 9.73 degrees+/-6.77 months. Computed tomography scans taken after surgery were reviewed to confirm the attempted screw trajectory correct and safety. RESULTS: Three of 93 lateral mass screws were malpositioned but clinical damage was not noted. Two of 8 pedicle screws on the T1 vertebrae were not placed on the correct pedicle area. Screw and plate loosening was observed in one case but was not subjected to an additional procedure because of maintained screw position observed during follow-up periods. CONCLUSION: The results of this study indicate that lateral mass screw fixation using the Modified Magerl's technique on the cervical lateral mass may provide safe and effective application on the patients. In addition, the chance of incorrectly placed screws was higher in T1 pedicle screw fixation than in lateral mass screw fixation of the cervical area.