Hyuk Hur

Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum

OBJECTIVE Ossification of the ligamentum flavum (OLF) is a rare cause of thoracic myelopathy. The aim of this study was to identify factors associated with the surgical outcome on the basis of preoperative clinical and radiological findings. METHODS Data obtained in 26 patients whot underwent posterior decompression for thoracic myelopathy, caused by thoracic OLF, were analyzed retrospectively. Patient age, duration of symptoms, OLF type, preoperative and postoperative neurological status using the Japanese Orthopedic Association (JOA) scoring system, surgical outcome, and other factors were reviewed. We compared the various factors and postoperative prognosis. All patients had undergone decompressive laminectomy and excision of the OLF. RESULTS Using the JOA score, the functional improvement was excellent in 8 patients, good in 14, fair in 2, and unchanged in 2. A mean preoperative JOA score of 6.65 improved to 8.17 after an average of 27.3 months. According to our analysis, age, gender, duration of symptoms, the involved spinal level, coexisting spinal disorders, associated trauma, intramedullary signal change, and dural adhesions were not related to the surgical outcome. However, the preoperative JOA score and type of OLF were the most important predictors of the surgical outcome. CONCLUSION Early diagnosis and sufficient surgical decompression could improve the functional prognosis for thoracic OLF. The postoperative results were found to be significantly associated with the preoperative severity of myelopathy and type of OLF.

Rutin improves functional outcome via reducing the elevated matrix metalloproteinase-9 level in a photothrombotic focal ischemic model of rats

BACKGROUND Blood-brain barrier (BBB) disruption mediated by proteases plays a pivotal role in neural tissue damage after acute ischemic stroke. In an animal stroke model, the activation of matrix metalloproteinases (MMPs), especially MMP-9, was significantly increased and it showed potential association with blood-brain barrier (BBB) disruption and cerebral edema. Theoretically, it is expected that early blockade of expression and activation of MMP-9 after ischemic stroke provides neuroprotective effects from secondary neural tissue damage. This study was aimed to determine the ability of rutin to influence MMP-9 expression, activity and BBB disruption using a photothrombotic focal ischemic model in rats. METHODS Adult male Sprague-Dawley rats, weighing between 250 and 300 g (aged 8 weeks) received focal cerebral ischemia by photothrombosis using Rose Bengal (RB) and cold light. Injured animals were divided into two groups; one group received 50mg/kg of rutin intraperitoneally, starting 1h after injury and at 12h intervals for 3 days, while animals in the control group received weight-adjusted doses of saline vehicle over the same period. In each group, the expressions and activities of MMP-9 were assessed by Western blot and gelatin zymography at 6, 24, 48, and 72 h after photothrombotic insult. The effects of rutin on BBB disruption and functional outcomes were also determined. RESULTS Western blot and zymographic analysis showed up-regulated MMP-9 expression and activity in the ischemic cortex. The expression and activity of MMP-9 were significantly elevated at 6h after photothrombotic insult, which remained up-regulated for at least until 72 h after injury. In the rutin-treated group, MMP-9 expression and activity were significantly attenuated at 6, 24, and 48 h compared to the control group. Relative to the control group, BBB permeability was significantly reduced in the rutin-treated group. The results of the rotarod test revealed that rutin treatment significantly improved functional outcomes. CONCLUSIONS Rutin treatment starting 1h after injury attenuated BBB disruption during photothrombotic focal ischemia, which was partly, at least, achieved through inhibitory effects on MMP-9 expression and activity. The results of this study suggest that rutin might be useful in clinical trials aimed to improve the outcome of patients suffering from acute ischemic stroke.

The transdural approach for thoracic disc herniations: a technical note

Surgery for thoracic disc herniations is still challenging, and the disc excision via a posterior laminectomy is considered risky. A variety of dorsolateral and ventral approaches have been developed. However, the lateral extracavitary and transthoracic approach require extensive surgical exposure. Therefore, we adopted a posterior transdural approach for direct visualization without entry into the thoracic cavity. Three cases that illustrate this procedure are reported here with the preoperative findings, radiological findings and surgical techniques used. After the laminectomy, at the involved level, the dorsal dura was opened with a longitudinal paramedian incision. The cerebrospinal fluid was drained to gain more operating space. After sectioning of the dentate ligaments, gentle retraction was applied to the spinal cord. Between the rootlets above and below, the ventral dural bulging was clearly observed. A small paramedian dural incision was made over the disc space and the protruded disc fragment was removed. Neurological symptoms were improved, and no surgery-related complication was encountered. The posterior transdural approach may offer an alternative surgical option for selected patients with thoracic paracentral soft discs, while limiting the morbidity associated with the exposure.

Cerebellar Glioblastoma Multiforme in an Adult

Primary cerebellar glioblastoma multiforme (GBM) is a rare tumor in adults that accounts for just 1% of all cases of GBM. Due to their rarity, cerebellar GBMs are not yet completely understood about the pathogenesis and the prognosis. Here, we present a case of GBM in a 69-year-old man. Neurologic examination revealed the presence of cerebellar signs. Magnetic resonance imaging (MRI) showed a 4.5 x 3.6 cm-sized, ill-defined, heterogeneously enhancing mass in the left cerebellum and two patchy hyperintense lesions in the right cerebellum with minimal enhancement. After operation, glioblastoma was histologically confirmed. Postoperative radiotherapy with concomitant and adjuvant temozolomide chemotherapy was subsequently followed. Here, a case of unusual GBM in the cerebellum is reported with review of literature regarding the pathogenesis, the differential diagnosis and prognosis. There was no evidence of recurrence during postoperative one year. This patient showed a good prognosis in spite of the multiple lesions.

Transdural approach for calcified central disc herniations of the upper lumbar spine. Technical note.

Disc herniations of the upper lumbar spine (L1-2 and L2-3) have a frequency of 1 to 2% of all disc herniations. During posterior discectomy after laminectomy, significant manipulation of the exiting nerve root is unavoidable because of the narrow lamina and the difficulty in mobilizing the nerve root. The authors adopted a transdural approach in patients with calcified central disc herniation at the L1-2 level to reduce the risk of nerve root injury. Four patients suffering from radiating pain together with back pain were treated using the transdural approach. Preoperative neuroimaging studies revealed severe central disc herniation with calcification at the L1-2 level. After laminectomy or laminotomy, the incised dura mater was tacked, and the cauda equina rootlets were gently retracted. An intentional durotomy was performed over its maximal bulging of the ventral dura. After meticulous dissection of dense adhesions between the disc herniation and the dural sac, adequate decompression with removal of calcified disc fragments and osteophytes was accomplished. Clinical symptoms improved in all patients. Postoperative permanent cerebrospinal fluid leakage and pseudomeningocele were not observed, and no patient had a progressive lumbar deformity at an average follow-up of 53 months. Transient mild motor weakness and sensory change were observed in two patients postoperatively; however, these symptoms resolved completely within 1 week. The posterior transdural approach offers an alternative in central calcified upper lumbar disc herniation when root retraction is dangerous.

Vertebral artery injury after cervical spine trauma: A prospective study using computed tomographic angiography.

Background: Although the vertebral artery injuries (VAI) associated with cervical spine trauma are usually clinically occult, they may cause fatal ischemic damage to the brain stem and cerebellum. Methods: We performed a prospective study using computed tomographic angiography (CTA) to determine the frequency of VAI associated with cervical spine injuries and investigate the clinical and radiological characteristics. Between January 2005 and August 2007, 99 consecutive patients with cervical spine fractures and/or dislocations were prospectively evaluated for patency of the VA, using the CTA, at the time of injury. Results: Complete disruption of blood flow through the VA was demonstrated in seven patients with unilateral occlusion (7.1%). There were four men and three women with a mean age of 43 (range, 33-55 years). Unilateral occlusion of the right vertebral artery occurred in four patients and of the left in three. Regarding the cervical injury type, two cases were cervical burst fractures (C6 and C7), two had C4-5 fracture/dislocations, two had a unilateral transverse foraminal fracture, and one had dens type III fracture. All patients presented with good patency of the contralateral VA. None of the patients developed secondary neurological deterioration due to vertebrobasilar ischemia during the follow-up period with a mean duration of 23 months. Conclusions: VAI should be suspected in patients with cervical trauma that have cervical spine fractures and/or dislocations or transverse foramen fractures. CTA was useful as a rapid diagnostic method for ruling out VAI after cervical spine trauma.

Effect of posterior subsidence on cervical alignment after anterior cervical corpectomy and reconstruction using titanium mesh cages in degenerative cervical disease

Subsidence after anterior cervical reconstruction using a titanium mesh cage (TMC) has been a matter of debate. The authors investigated and analyzed subsidence and its effect on clinical and radiologic parameters after cervical reconstruction using a TMC for degenerative cervical disease. Thirty consecutive patients with degenerative cervical spine disorders underwent anterior cervical corpectomy followed by reconstruction with TMC. Twenty-four patients underwent a single-level corpectomy, and six patients underwent a two-level corpectomy. Clinical outcomes were assessed using a Visual Analogue Scale (VAS), the Japanese Orthopedic Association (JOA) score and the Neck Disability Index (NDI). Fusion status, anterior and posterior subsidence of the TMC, segmental angle (SA) and cervical sagittal angle (CSA) were assessed by lateral and flexion-extension radiographs of the neck. The mean follow-up period was 27.6 months (range, 24 to 49 months). The VAS, NDI and JOA scores were all significantly improved at the last follow-up. No instances of radiolucency or motion-related pseudoarthrosis were detected on radiographic analysis, yielding a fusion rate of 100%. Subsidence occurred in 28 of 30 patients (93.3%). The average anterior subsidence of the cage was 1.4 ± 0.9 mm, and the average posterior subsidence was 2.9 ± 1.2 mm. The SA and CSA at the final follow-up were significantly increased toward a lordotic angle. Anterior cervical reconstruction using TMC and plating in patients with cervical degenerative disease provides good clinical and radiologic outcomes. Cage subsidence occurred frequently, especially at the posterior part of the cage. Despite the prominent posterior subsidence of the TMC, SA and CSA were improved on final follow-up radiographs, suggesting that posterior subsidence may contribute to cervical lordosis.

Predictive factors for a kyphosis recurrence following short-segment pedicle screw fixation including fractured vertebral body in unstable thoracolumbar burst fractures.

Objective The technique of short segment pedicle screw fixation (SSPSF) has been widely used for stabilization in thoracolumbar burst fractures (TLBFs), but some studies reported high rate of kyphosis recurrence or hardware failure. This study was to evaluate the results of SSPSF including fractured level and to find the risk factors concerned with the kyphosis recurrence in TLBFs. Methods This study included 42 patients, including 25 males and 17 females, who underwent SSPSF for stabilization of TLBFs between January 2003 and December 2010. For radiologic assessments, Cobb angle (CA), vertebral wedge angle (VWA), vertebral body compression ratio (VBCR), and difference between VWA and Cobb angle (DbVC) were measured. The relationships between kyphosis recurrence and radiologic parameters or demographic features were investigated. Frankel classification and low back outcome score (LBOS) were used for assessment of clinical outcomes. Results The mean follow-up period was 38.6 months. CA, VWA, and VBCR were improved after SSPSF, and these parameters were well maintained at the final follow-up with minimal degree of correction loss. Kyphosis recurrence showed a significant increase in patients with Denis burst type A, load-sharing classification (LSC) score >6 or DbVC >6 (p<0.05). There were no patients who worsened to clinical outcome, and there was no significant correlation between kyphosis recurrence and clinical outcome in this series. Conclusion SSPSF including the fractured vertebra is an effective surgical method for restoration and maintenance of vertebral column stability in TLBFs. However, kyphosis recurrence was significantly associated with Denis burst type A fracture, LSC score >6, or DbVC >6.

Comparison of Clinical and Radiologic Results between Expandable Cages and Titanium Mesh Cages for Thoracolumbar Burst Fracture

Objective A thoracolumbar burst fracture is usually unstable and can cause neurological deficits and angular deformity. Patients with unstable thoracolumbar burst fracture usually need surgery for decompression of the spinal canal, correction of the angular deformity, and stabilization of the spinal column. We compared two struts, titanium mesh cages (TMCs) and expandable cages. Methods 33 patients, who underwent anterior thoracolumbar reconstruction using either TMCs (n=16) or expandable cages (n=17) between June 2000 and September 2011 were included in this study. Clinical outcome was measured by visual analogue scale (VAS), American Spinal Injury Association (ASIA) scale and Low Back Outcome Score (LBOS) for functional neurological evaluation. The Cobb angle, body height of the fractured vertebra, the operation time and amount of intra-operative bleeding were measured in both groups. Results In the expandable cage group, operation time and amount of intraoperative blood loss were lower than that in the TMC group. The mean VAS scores and LBOS in both groups were improved, but no significant difference. Cobb angle was corrected higher than that in expandable cage group from postoperative to the last follow-up. The change in Cobb angles between preoperative, postoperative, and the last follow-up did not show any significant difference. There was no difference in the subsidence of anterior body height between both groups. Conclusion There was no significant difference in the change in Cobb angles with an inter-group comparison, the expandable cage group showed better results in loss of kyphosis correction, operation time, and amount of intraoperative blood loss.

Subsidence after single-level anterior cervical fusion with a stand-alone cage

To investigate the risk factors for subsidence in patients treated with stand-alone anterior cervical discectomy and fusion (ACDF) using polyetheretherketone (PEEK) cages for single-level degenerative cervical disease. Seventy-seven consecutive patients who underwent single-level stand-alone ACDF with a PEEK cage between 2005 and 2012 were included. Subsidence was defined as a decrease in the interbody height of more than 3mm on radiographs at the 1-year follow-up compared with that in the immediate post-operative image. Patients were divided into the subsidence and non-subsidence groups. The following factors were investigated in relation to the occurrence of subsidence: age, pre-operative overall cervical sagittal angle, segmental angle of the operated level, interbody height, cage height, cage devices and cage location (distance between anterior margin of the body endplate and that of the cage). The clinical outcomes were assessed with visual analog scale, modified Japanese Orthopedic Association score and neck disability index. Twenty-six out of the 77 (33.8%) patients had radiological signs of cage subsidence. Solid fusion was achieved in 25 out of the 26 patients (96.2%) in the subsidence group and in 47 out of the 51 patients (92.2%) in the non-subsidence group. More than 3mm distance between anterior margin of the vertebral body and that of the cage was significantly associated with subsidence (p<0.05). However, subsidence did not correlate with fusion rate or clinical outcomes. Cage location was the only significant risk factor. Therefore, cage location should be taken into consideration during stand-alone ACDF using PEEK cages.