Percutaneous Stenoscopic Lumbar Decompression with Paramedian Approach for Foraminal/Extraforaminal Lesions

The lumbar foramen is affected by different degenerative diseases, including extraforaminal disc herniation, foraminal stenosis (FS), and degenerative or spondylolytic spondylolisthesis. The purpose of this study was to describe percutaneous stenoscopic lumbar decompression with a paramedian approach (para-PSLD) for foraminal/extraforaminal lesions. All operative procedures were performed using a complete uniportal endoscopic instrument system. The para-PSLD can be easily applied to patients with FS and narrow disc space or facet joint hypertrophy. The anatomical view of a para-PSLD is similar to that of a conventional open surgery and allows for good visualization of the foraminal/extraforaminal areas. We suggest that para-PSLD is an alternative and minimally invasive procedure to treat degenerative lumbar foraminal/extraforaminal stenoses.

Therapeutic Feasibility of Full Endoscopic Decompression in One- to Three-Level Lumbar Canal Stenosis via a Single Skin Port Using a New Endoscopic System, Percutaneous Stenoscopic Lumbar Decompression

STUDY DESIGN: This retrospective study involved 450 consecutive cases of degenerative lumbar stenosis treated with percutaneous stenoscopic lumbar decompression (PSLD). PURPOSE: We determined the feasibility of PSLD for lumbar stenosis at single and multiple levels (minimum 1-year follow-up) by image analysis to observe postoperative widening of the vertebral canal in the area. OVERVIEW OF LITERATURE: The decision not to perform an endoscopic decompression might be due to the surgeon being uncomfortable with conventional microscopic decompression or unfamiliar with endoscopic techniques or the unavailability of relevant surgical tools to completely decompress the spinal stenosis. METHODS: The decompressed canal was compared between preoperative controls and postoperative treated cases. Data on operative results, including length of stay, operative time, and surgical complications, were analyzed. Patients were assessed clinically on the basis of the Visual Analog Scale (VAS) score for the back and legs and using the Oswestry Disability Index (ODI). RESULTS: Postoperative magnetic resonance imaging revealed that PSLD increased the canal cross-sectional area by 52.0% compared with the preoperative area at the index segment (p<0.001) and demonstrated minimal damage to the normal soft tissues including muscles and the extent of removed normal bony tissues. Mean improvements in VAS score and ODI were 4.0 (p<0.001) and 40% (p<0.001), respectively. CONCLUSIONS: PSLD could be an alternative to microscopic or microendoscopic decompression with various advantages in the surgical management of lumbar stenosis.

Are Controversial Issues in Cervical Total Disc Replacement Resolved or Unresolved?: A Review of Literature and Recent Updates

Since the launch of cervical total disc replacement (CTDR) in the early 2000s, many clinical studies have reported better outcomes of CTDR compared to those of anterior cervical discectomy and fusion. However, CTDR is still a new and innovative procedure with limited indications for clinical application in spinal surgery, particularly, for young patients presenting with soft disc herniation with radiculopathy and/or myelopathy. In addition, some controversial issues related to the assessment of clinical outcomes of CTDR remain unresolved. These issues, including surgical outcomes, adjacent segment degeneration (ASD), heterotopic ossification (HO), wear debris and tissue reaction, and multilevel total disc replacement (TDR) and hybrid surgeries are a common concern of spine surgeons and need to be resolved. Among them, the effect of CTDR on patient outcomes and ASD is theoretically and clinically important; however, this issue remains disputable. Additionally, HO, wear debris, multilevel TDR, and hybrid surgery tend to favor CTDR in terms of their effects on outcomes, but the potential of these factors for jeopardizing patients' safety postoperatively and/or to exert harmful effects on surgical outcomes in longer-term follow-up cannot be ignored. Consequently, it is too early to determine the therapeutic efficacy and cost-effectiveness of CTDR and will require considerable time and studies to provide appropriate answers regarding the same. For these reasons, CTDR requires longer-term follow-up data.

Comparison of Root Images between Post-Myelographic Computed Tomography and Magnetic Resonance Imaging in Patients with Lumbar Radiculopathy

OBJECTIVE: To evaluate the diagnostic value of computed tomography-myelography (CTM) compared to that of magnetic resonance imaging (MRI) in patients with lumbar radiculopathy. METHODS: The study included 91 patients presenting with radicular leg pain caused by herniated nucleus pulposus or lateral recess stenosis in the lumbar spine. The degree of nerve root compression on MRI and CTM was classified into four grades. The results of each imaging modality as assessed by two different observers were compared. Visual analog scale score for pain and electromyography result were the clinical parameters used to evaluate the relationships between clinical features and nerve root compression grades on both MRI and CTM. These relationships were quantified by calculating the receiver-operating characteristic curves, and the degree of relationship was compared between MRI and CTM. RESULTS: McNemar's test revealed that the two diagnostic modalities did not show diagnostic concurrence (p<0.0001). Electromyography results did not correlate with grades on either MRI or CTM. The visual analog pain scale score results were correlated better with changes of the grades on CTM than those on MRI (p=0.0007). CONCLUSION: The present study demonstrates that CTM could better define the pathology of degenerative lumbar spine diseases with radiculopathy than MRI. CTM can be considered as a useful confirmative diagnostic tool when the exact cause of radicular pain in a patient with lumbar radiculopathy cannot be identified by using MRI. However, the invasiveness and potential complications of CTM are still considered to be pending questions to settle.

A Nationwide Retrospective Study of Opioid Management Patterns in 2,468 Patients with Spinal Pain in Korea

STUDY DESIGN: Retrospective patient data collection and investigator survey. PURPOSE: To investigate patterns of opioid treatment for pain caused by spinal disorders in Korea. OVERVIEW OF LITERATURE: Opioid analgesic prescription and adequacy of consumption measures in Korea have markedly increased in the past decade, suggesting changing patterns in pain management practice; however, there is lack of integrated data specific to Korean population. METHODS: Patient data were collected from medical records at 34 university hospitals in Korea. Outpatients receiving opioids for pain caused by spinal disorders were included in the study. Treatment patterns, including opioid types, doses, treatment duration, outcomes, and adverse drug reactions (ADRs), were evaluated. Investigators were interviewed on their perceptions of opioid use for spinal disorders. RESULTS: Among 2,468 analyzed cases, spinal stenosis (42.8%) was the most common presentation, followed by disc herniation (24.2%) and vertebral fracture (17.5%). In addition, a greater proportion of patients experienced severe pain (73.9%) rather than moderate (19.9%) or mild (0.7%) pain. Oxycodone (51.9%) and fentanyl (50.8%) were the most frequently prescribed opioids; most patients were prescribed relatively low doses. The median duration of opioid treatment was 84 days. Pain relief was superior in patients with longer treatment duration (≥2 months) or with nociceptive pain than in those with shorter treatment duration or with neuropathic or mixed-type pain. ADRs were observed in 8.6% of cases. According to the investigators' survey, "excellent analgesic effect" was a perceived advantage of opioids, while safety concerns were a disadvantage. CONCLUSIONS: Opioid usage patterns in patients with spinal disorders are in alignment with international guidelines for spinal pain management. Future prospective studies may address the suitability of opioids for spinal pain treatment by using appropriate objective measurement tools.

Total Disc Replacement in Lumbar Degenerative Disc Diseases

More than 10 years have passed since lumbar total disc replacement (LTDR) was introduced for the first time to the world market for the surgical management of lumbar degenerative disc disease (DDD). It seems like the right time to sum up the relevant results in order to understand where LTDR stands on now, and is heading forward to. The pathogenesis of DDD has been currently settled, but diagnosis and managements are still controversial. Fusion is recognized as golden standard of surgical managements but has various kinds of shortcomings. Lately, LTDR has been expected to replace fusion surgery. A great deal of LTDR reports has come out. Among them, more than 5-year follow-up prospective randomized controlled studies including USA IDE trials were expected to elucidate whether for LTDR to have therapeutic benefit compared to fusion. The results of these studies revealed that LTDR was not inferior to fusion. Most of clinical studies dealing with LTDR revealed that there was no strong evidence for preventive effect of LTDR against symptomatic degenerative changes of adjacent segment disease. LTDR does not have shortcomings associated with fusion. However, it has a potentiality of the new complications to occur, which surgeons have never experienced in fusion surgeries. Consequently, longer follow-up should be necessary as yet to confirm the maintenance of improved surgical outcome and to observe any very late complications. LTDR still may get a chance to establish itself as a substitute of fusion both nominally and virtually if it eases the concerns listed above.

Sagittal Sacropelvic Morphology and Balance in Patients with Sacroiliac Joint Pain Following Lumbar Fusion Surgery

OBJECTIVE: To investigate the sagittal sacropelvic morphology and balance of the patients with SIJ pain following lumbar fusion. METHODS: Among 452 patients who underwent posterior lumbar interbody fusion between June 2009 and January 2013, patients with postoperative SIJ pain, being responded to SIJ block were enrolled. For a control group, patients matched for sex, age group, the number of fused level and fusion to sacrum were randomly selected. Patients were assessed radiologic parameters including lumbar lordosis, pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). To evaluate the sagittal sacropelvic morphology and balance, the ratio of PT/PI, SS/PI and PT/SS were analyzed. RESULTS: A total of 28 patients with SIJ pain and 56 patients without SIJ pain were assessed. Postoperatively, SIJ pain group showed significantly greater PT (p=0.02) than non-SIJ pain group. Postoperatively, PT/PI and SS/PI in SIJ pain group was significantly greater and smaller than those in non-SIJ pain group respectively (p=0.03, 0.02, respectively) except for PT/SS (p=0.05). SIJ pain group did not show significant postoperative changes of PT/PI and SS/PI (p=0.09 and 0.08, respectively) while non-SIJ pain group showed significantly decrease of PT/PI (p=0.00) and increase of SS/PI (p=0.00). CONCLUSION: This study presents different sagittal sacropelvic morphology and balance between the patients with/without SIJ pain following lumbar fusion surgery. The patients with SIJ pain showed retroversed pelvis and vertical sacrum while the patients without SIJ pain have similar morphologic features with asymptomatic populations in the literature.

Direct Pars Repair Surgery Using Two Different Surgical Methods : Pedicle Screw with Universal Hook System and Direct Pars Screw Fixation in Symptomatic Lumbar Spondylosis Patients

OBJECTIVE: The authors performed a retrospective study to assess the clinical and radiological outcome in symptomatic lumbar spondylolysis patients who underwent a direct pars repair surgery using two different surgical methods; pedicle screw with universal hook system (PSUH) and direct pars screw fixation (DPSF), and compared the results between two different treated groups. METHODS: Forty-seven consecutive patients (PSUH; 23, DPSF; 15) with symptomatic lumbar spondylolysis who underwent a direct pars repair surgery were included. The average follow-up period was 37 months in the PSUH group, and 28 months in the DPSF group. The clinical outcome was measured using visual analogue pain scale (VAS) and Oswestry disability index (ODI). The length of operation time, the amount of blood loss, the duration of hospital stay, surgical complications, and fusion status were also assessed. RESULTS: When compared to the DPSF group, the average preoperative VAS and ODI score of the PSUH group were less decreased at the last follow-up; (the PSUH group; back VAS : 4.9 vs. 3.0, leg VAS : 6.8 vs. 2.2, ODI : 50.6% vs. 24.6%, the DPSF group; back VAS : 5.7 vs. 1.1, leg VAS : 6.1 vs. 1.2, ODI : 57.4% vs. 18.2%). The average operation time was 174.9 minutes in the PSUH group, and 141.7 minutes in the DPSF group. The average blood loss during operation was 468.8 cc in the PSUH group, and 298.8 cc in the DPSF group. The average hospital stay after operation was 8.9 days in the PSUH group, and 7 days in the DPSF group. In the PSUH group, there was one case of a screw misplacement requiring revision surgery. In the DPSF group, one patient suffered from transient leg pain. The successful bone fusion rate was 78.3% in the PSUH group, and 93.3% in the DPSF group. CONCLUSION: The present study suggests that the technique using direct pars screw would be more effective than the method using pedicle screw with lamina hook system, in terms of decreased operation time, amount of blood loss, hospital stay, and increased fusion success rate, as well as better clinical outcome.

Iatrogenic Intradural Lumbosacral Cyst Following Epiduroscopy

We report a rare complication of iatrogenic spinal intradural following minimally invasive extradural endoscopic procedues in the lumbo-sacral spines. To our knowledge, intradural cyst following epiduroscopy has not been reported in the literature. A 65-year-old woman with back pain related with previous lumbar disc surgery underwent endoscopic epidural neuroplasty and nerve block, but her back pain much aggravated after this procedure. Postoperative magnetic resonance imaging revealed a large intradural cyst from S1-2 to L2-3 displacing the nerve roots anteriorly. On T1 and T2-weighted image, the signal within the cyst had the same intensity as cerebrospinal fluid. The patient underwent partial laminectomy of L5 and intradural exploration, and fenestration of the cystic wall was accomplished. During operation, the communication between the cyst and subarachnoid space was not identified, and the content of the cyst was the same as that of cerebrospinal fluid. Postoperatively, the pain attenuated immediately. Incidental durotomy which occurred during advancing the endoscope through epidural space may be the cause of formation of the intradural cyst. Intrdural cyst should be considered, if a patient complains of new symptoms such as aggravation of back pain after epiduroscopy. Surgical treatment, simple fenestration of the cyst may lead to improved outcome. All the procedures using epiduroscopy should be performed with caution.

Accuracy and Safety in Pedicle Screw Placement in the Thoracic and Lumbar Spines : Comparison Study between Conventional C-Arm Fluoroscopy and Navigation Coupled with O-Arm(R) Guided Methods

OBJECTIVE: The authors performed a retrospective study to assess the accuracy and clinical benefits of a navigation coupled with O-arm(R) system guided method in the thoracic and lumbar spines by comparing with a C-arm fluoroscopy-guided method. METHODS: Under the navigation guidance, 106 pedicle screws inserted from T7 to S1 in 24 patients, and using the fluoroscopy guidance, 204 pedicle screws from T5 to S1 in 45 patients. The position of screws within the pedicle was classified into four groups, from grade 0 (no violation cortex) to 3 (more than 4 mm violation). The location of violated pedicle cortex was also assessed. Intra-operative parameters including time required for preparation of screwing procedure, times for screwing and the number of X-ray shot were assessed in each group. RESULTS: Grade 0 was observed in 186 (91.2%) screws of the fluoroscopy-guided group, and 99 (93.4%) of the navigation-guided group. Mean time required for inserting a screw was 3.8 minutes in the fluoroscopy-guided group, and 4.5 minutes in the navigation-guided group. Mean time required for preparation of screw placement was 4 minutes in the fluoroscopy-guided group, and 19 minutes in the navigation-guided group. The fluoroscopy-guided group required mean 8.9 times of X-ray shot for each screw placement. CONCLUSION: The screw placement under the navigation-guidance coupled with O-arm(R) system appears to be more accurate and safer than that under the fluoroscopy guidance, although the preparation and screwing time for the navigation-guided surgery is longer than that for the fluoroscopy-guided surgery.

Heterotopic Ossification Following Cervical Total Disc Replacement: Iatrogenic or Constitutional?

OBJECTIVE: To elucidate etiological factors of heterotopic ossification (HO) by evaluating retrospectively if HO is a unique finding following cervical total disc replacement (CTDR) or a finding observable following an anterior cervical interbody fusion (ACIF). METHODS: The authors had selected 87 patients who underwent anterior cervical surgery (TDR or ACIF), and could be followed up more than 24 months. A cervical TDR was performed using a Bryan disc or a ProDisc-C and an ACIF using a stand-alone cage or fibular allograft with a plate and screws system. The presence of HO was determined by observing plain radiography at the last follow up. The relation between HO occurrence and specific preoperative radio-logical findings (osteophyte and calcification of posterior longitudinal ligament (PLL)) at the index level was investigated. RESULTS: Cervical TDR was performed in 40 patients (43 levels) and ACIF in 47 patients (54 levels). At the final radiographs, HO was demonstrated at 27 levels (TDR-Bryan; 8/18, TDR-Prodisc-C; 12/25, ACIF-cage alone; 7/29, and ACIF-plate screw; 0/25). Mean ROM at the last follow-up of each TDR subgroup were 7.8+/-4.7degrees in Bryan, 3.89+/-1.77degrees in Prodisc-C, and it did not correlated with the incidence of HO. Fusion status of ACIF groups was observed as 2 case of grade 1, 6 of grade 2, and 21 of grade 3 in cage alone subgroup, and no case of grade 1, 4 of grade 2, and 21 of grade 3 in plate screw subgroup. Fusion status in ACIF-cage alone subgroup was significantly related to the HO incidence. The preoperative osteophyte at the operated level observed in 27 levels, and HO was demonstrated in 12 levels (TDR-Bryan; 3/5, TDR-Prodisc-C; 2/3, ACIF-cage alone; 7/11, and ACIF-plate screw; 0/8). Preoperative PLL calcification at the operated level was observed 22 levels, and HO was defined at 14 levels (TDR-Bryan; 5/5, TDR-Prodisc-C; 4/5, ACIF-cage alone; 5/7, and ACIF-plate screw; 0/5). The evidence of preoperative osteophyte and PLL calcification showed statistically significant relations to the occurrence of HO. CONCLUSION: HO was observed in both TDR and ACIF groups. HO was more frequently occurred in TDR group regardless of prosthesis type. In ACIF group, only cage alone subgroup showed HO, with relation to fusion status. Preoperative calcification of longitudinal ligaments and osteophyte were strongly related to the occurrence of HO.

Unrecognized Shoulder Disorders in Treatment of Cervical Spondylosis Presenting Neck and Shoulder Pain

OBJECTIVE: Cervical spondylosis and shoulder disorders share with neck and shoulder pain. Differentiating between the two can be challenging and patient with combined pathologies is less likely to have pain improvement even after successful cervical operation. We investigated clinical characteristics of the patients who were diagnosed as cervical spondylosis however, were turned out to have shoulder disorders or the patients whose pain was solely originated from shoulder. METHODS: Between January 2008 and October 2009, the patients presenting neck and shoulder pain with diagnosis of cervical spondylosis were enrolled. Among them, the patients who met following inclusion criteria were grouped into shoulder disorder group and the others were into cervical spondylosis group. Inclusion criteria were as follows. (1) To have residual or unresponsive neck and shoulder pain despite of optimal surgical treatment due to concomitant shoulder disorders. (2) When the operation was cancelled for the reason that shoulder and neck pain was proved to be related with unrecognized shoulder disorders. The authors retrospectively reviewed and compared clinical characteristics, level of pathology, diagnosis of cervical spondylosis and shoulder disorders. RESULTS: A total of 96 patients were enrolled in this study. Shoulder disorder group was composed of 15 patients (15.8%) and needed additional orthopedic treatment. Cervical spondylosis group was composed of 81 patients (84.2%). There was no significant differences in mean age, sex ratio and major diagnosis in both shoulder disorder and cervical spondylosis group (p=0.33, 0.78, and 0.68 respectively). However, the distribution of pathologic levels was found to be significantly different (p=0.03). In shoulder disorder group, the majority of lesions (15 of 19 levels, 78.9%) were located at the level of C4-5 (36.8%) and C5-6 (42.1%). On the other hand, in cervical spondylosis group, C5-6 (39.0%) and C6-7 (37.1%) were the most frequently observed level of lesions (80 of 105 levels, 16.1%). CONCLUSION: It is very important for spine surgeons to perform a complete history taking and physical examination using the special tests, and to discover the underlying shoulder disorders causing of symptom in treatment of cervical spondylosis presenting neck and shoulder pain.

Correlation between the Symptomatic Lumbar Synovial Cyst and Facet Degeneration: Retrospective Study of 13 Surgical Cases

OBJECTIVE: This retrospective study of 13 patients who underwent surgical treatment for symptomatic lumbar synovial cyst was performed to evaluate the clinical findings and pathogenesis of lumbar synovial cyst. METHODS: The clinical characteristics of the patients were investigated by reviewing the hospital records, preoperative radiological images, and operation records. By observing preoperative CT scans Facet degeneration grade at the lesion and opposite side of pathologic level and adjacent levels were assessed and compared. RESULTS: There were 5 males and 8 females (average 65.8 year-old). Six patients presented with low back pain and leg pain, and 7 patients presented only leg pain. Most common pathologic level was L4-5. All patients underwent the cyst resection with/without decompressive laminectomy or discectomy. The additional instrumentation was not performed in all patients. No complications or recurrence was observed during average 34.5 months follow-up. There was no significant difference of facet degeneration grade between the lesion side of pathologic level and opposite side of same level or lower adjacent level. CONCLUSION: In the present study, all patients showed clinical improvement by the simple surgery without any instrumentation. No significant correlation between the occurrence of synovial cyst and the degeneration grade of facet joint was revealed.

Clinical Results of Interlaminar Approach for Endoscopic Discectomy in the Herniated Lumbar Disc at L5-S1

OBJECTIVE: This retrospective study of 57 patients was performed to evaluate the therapeutic effectiveness of percutaneous endoscopic surgery by using interlaminar approach (ILA) in symptomatic lumbar disc herniation (LDH) at L5-S1. METHODS: Visual analogue pain score (VAS) and Oswestry disability index (ODI) were used to assess the clinical outcome. All assessment was done on 1 day before the operation, 3 days, 3months and 12months after the operation. RESULTS: The mean preoperative back and leg VAS was decreased from 5.6+/-1.4, 8.5+/-1.7 to 1.8+/-1.2, 1.5+/-1.3 at 3 days, 1.2+/-1.1, 1.8+/-1.7 at 3 months, and 1.4+/-1.7, 1.6+/-1.3 at 12 months after the operation. Mean preoperative ODI score was improved from 46.8+/-22.4% to 17.7+/-11.6% at 3 days, 15.3+/-10.1% at 3 months, and 16.2+/-9.3% at 12 months after the operation. There were 2 cases of surgical failure due to dural tearing and calcified disc. One patient presented with transient paresthesia postoperatively. Two patients showed the recurrent disc herniation at the same level and same side, and underwent second open surgery. CONCLUSION: The present study revealed that percutaneous endoscopic surgery by using ILA is an effective surgical modality for the selective cases of LDH at L5-S1.

Thoracic Intramedullary Schwannoma Accompanying by Extramedullary Beads-Like Daughter Schwanommas

Thoracic intramedullary schwannomas are rare spinal cord tumors. Most of these tumors have been reported as a single lesion in the spinal cord. The authors report the first case of intramedullary schwannoma accompanying by extramedullary beads-like daughter masses of the thoracic spine. A 68-year-old male presented with walking disturbance and decreased sensation below T10 dermatome. Imaging workup revealed an intramedullary mass at T6 and T7. T6 and T7 laminectomy and mass removal were performed. Intraoperatively, extramedullary beads-like daughter masses along the nerve roots adjacent to intramedullary mass were identified. Total removal of intramedullary lesion and partial resection of extramedullary masses were done. Histological analysis confirmed the diagnosis of schwannoma. The patient could ambulate independently at postoperative 1 month without any neurological sequelae. The authors experienced a surgical case of intramedullary schwannoma accompanying by extramedullary beads-like same pathologies in the thoracic spine.

Surgical Outcome of Extreme Lateral Transforaminal Endoscopic Discectomy in the Herniated Lumbar Disc

OBJECTIVE: This retrospective study of 101 patients with symptomatic lumbar disc herniation (LDH) treated via percutaneous endoscopic surgery using the extreme lateral transforaminal approach (ELTFA) was performed to assess the clinical results and to determine the relationship between the location of the herniated disc fragment and surgical success. METHODS: The operated levels were distributed as one case of L2-3, ten cases of L3-4, 83 cases of L4-5 and seven cases of L5-6. The clinical outcomes were assessed using visual analogue pain (VAS), Oswestry disability index (ODI) and MacNab's criteria. All assessments were performed one day prior to the operation, as well as three days and one month after the operation. RESULTS: Mean preoperative back VAS (4.33+/-1.48) and leg VAS (6.29+/-2.72) were significantly decreased three days (1.43+/-1.48, 2.03+/-1.98, respectively) and one month (1.23+/-1.25, 1.89+/-1.72, respectively) postoperatively. Mean preoperative ODI score was improved from 45.86+/-20.44% to 18.92+/-12.98% after three days and to 16.34+/-9.86% one month after operation. Twenty-three patients showed a vertical migration of the herniated disc of greater than 4 mm. There was no statistically significant difference between the extents of improvement in VAS or ODI score or between the degrees of vertical migration. According to MacNab's criteria assessment, the overall surgical success rate, as measured by surgeries classified as "excellent" and "good," was 89.8%. Surgical complications included seven patients with transient leg paresthesia, one patient with transient motor weakness and one patient with postoperative discitis. CONCLUSION: This study demonstrates that percutaneous endoscopic surgery using ELTFA is an effective surgical endoscopic approach for selected LDH patients. This procedure is safe and could expand indications to vertically migrated discs.

A Chordoma of the Thoracic Spine: A Case Report

A 52-year-old woman presented with a thoracic chordoma at T1-3 level as abnormal sensations on the trunk and low extremities and both legs weakness. Almost total resection was possible through posterolateral costotransversectomy. The patient could ambulate at 3 days after the operation without any sequelae. Histologic study revealed a malignant chordoma with no sarcomatous differentiation.

O-arm(R) Imaging System Coupled with Navigation Guided Posterior Atlantoaxial Screw Fixation in the Patient with Ponticulus Posticus, an Anatomical Variation of Atlas

Ponticulus posticus is an abnormal bony bridge of posterior arch of atlas. The resulting foramen contains the vertebral artery and has clinical significance in lateral mass screw insertion into the first cervical vertebra. The authors report an atlantoaxial subluxation case showing a ponticulus posticus, which was surgically treated with posterior atlantoaxial screw fixation under the guidance of O-arm(R) imaging system coupled with navigation.

Bow Hunter's Stroke Caused by a Severe Facet Hypertrophy of C1-2

Bow hunter's stroke is a rare symptomatic vertebrobasilar insufficiency in which vertebral artery (VA) is mechanically occluded during head rotation. Various pathologic conditions have been reported as causes of bow hunter's stroke. However, bow hunter's stroke caused by facet hypertrophy of C1-2 has not been reported. A 71-year-old woman presented with symptoms of vertebrobasilar insufficiency. Spine computed tomography showed massive facet hypertrophy on the left side of C1-2 level. A VA angiogram with her head rotated to the right revealed significant stenosis of left VA. C1-2 posterior fixation and fusion was performed to prevent serious neurologic deficit from vertebrobasilar stroke.

Cervical Schwannoma Presenting with Acute Intracranial Subarachnoid Hemorrhage

A subarachnoid hemorrhage (SAH) associated with negative finding on four-vessel angiography is seen in 5 to 30% of patients with intracranial SAH. A previously silent lesion in the spinal canal may be responsible for the angiographically negative finding for cause of intracranial SAH. We report a case of upper cervical (C1-2) intradural schwannoma presenting with acute intracranial SAH. Repeated cerebral angiographic studies were negative, but cervical magnetic resonance imaging study and tissue pathology revealed a intradural-extramedullary schwannoma in C1-2 level. This case illustrates the importance of a high index of clinical suspicion for spinal disease in angiographically negative intracranial SAH patients.