Radiological Changes in Adjacent and Index Levels after Cervical Disc Arthroplasty

Purpose@#The purpose of this retrospective study was to evaluate radiological and clinical outcomes in patients undergoing cervical disc arthroplasty (CDA) for cervical degenerative disc disease. The results may assist in surgical decision-making and enable more effective and safer implementation of cervical arthroplasty. @*Materials and Methods@#A total of 125 patients who were treated with CDA between 2006 and 2019 were assessed. Radiological measurements and clinical outcomes included the visual analogue scale (VAS), the Neck Disability Index (NDI), and the Japanese Orthopaedic Association (JOA) myelopathy score assessment preoperatively and at ≥2 years of follow-up. @*Results@#The mean follow-up period was 38 months (range, 25–114 months). Radiographic data demonstrated mobility at both the index and adjacent levels, with no signs of hypermobility at an adjacent level. There was a non-significant loss of cervical global motion and range of motion (ROM) of the functional spinal unit at the operated level, as well as the upper and lower adjacent disc levels, compared to preoperative status. The cervical global and segmental angle significantly increased. Postoperative neck VAS, NDI, and JOA scores showed meaningful improvements after one- and two-level CDA. We experienced a 29.60% incidence of heterotrophic ossification and a 3.20% reoperation rate due to cervical instability, implant subsidence, or osteolysis. @*Conclusion@#CDA is an effective surgical technique for optimizing clinical outcomes and radiological results. In particular, the preservation of cervical ROM with an artificial prosthesis at adjacent and index levels and improvement in cervical global alignment could reduce revision rates due to adjacent segment degeneration.

Inter- and Intra-Observer Variability of the Volume of Cervical Ossification of the Posterior Longitudinal Ligament Using Medical Image Processing Software

OBJECTIVE: Computed tomography (CT)-based method of three dimensional (3D) analysis (MIMICS®, Materialise, Leuven, Belgium) is reported as very useful software for evaluation of OPLL, but its reliability and reproducibility are obscure. This study was conducted to evaluate the accuracy of MIMICS® system, and inter- and intra-observer reliability in the measurement of OPLL. METHODS: Three neurosurgeons independently analyzed the randomly selected 10 OPLL cases with medical image processing software (MIMICS®) which create 3D model with Digital Imaging and Communication in Medicine (DICOM) data from CT images after brief explanation was given to examiners before the image construction steps. To assess the reliability of inter- and intra-examiner intraclass correlation coefficient (ICC), 3 examiners measured 4 parameters (volume, length, width, and length) in 10 cases 2 times with 1-week interval. RESULTS: The inter-examiner ICCs among 3 examiners were 0.996 (95% confidence interval [CI], 0.987–0.999) for volume measurement, 0.973 (95% CI, 0.907–0.978) for thickness, 0.969 (95% CI, 0.895–0.993) for width, and 0.995 (95% CI, 0.983–0.999) for length. The intra-examiner ICCs were 0.994 (range, 0.991–0.996) for volume, 0.996 (range, 0.944–0.998) for length, 0.930 (range, 0.873–0.947) for width, and 0.987 (range, 0.985–0.995) for length. CONCLUSION: The medical image processing software (MIMICS®) provided detailed quantification OPLL volume with minimal error of inter- and intra-observer reliability in the measurement of OPLL.

Allen (Horace N. Allen, 安連, 1858–1932)

No abstract available.

Sacral Reconstruction with a 3D-Printed Implant after Hemisacrectomy in a Patient with Sacral Osteosarcoma: 1-Year Follow-Up Result

Pelvic reconstruction after sacral resection is challenging in terms of anatomical complexity, excessive loadbearing, and wide defects. Nevertheless, the technological development of 3D-printed implants enables us to overcome these difficulties. Here, we present a case of sacral osteosarcoma surgically treated with hemisacrectomy and sacral reconstruction using a 3D-printed implant. The implant was printed as a customized titanium prosthesis from a 3D real-sized reconstruction of a patient's CT images. It consisted mostly of a porous mesh and incorporated a dense strut. After 3-months of neoadjuvant chemotherapy, the patient underwent hemisacretomy with preservation of contralateral sacral nerves. The implant was anatomically installed on the defect and fixed with a screw-rod system up to the level of L3. Postoperative pain was significantly low and the patient recovered sufficiently to walk as early as 2 weeks postoperatively. The patient showed left-side foot drop only, without loss of sphincter function. In 1-year follow-up CT, excellent bony fusion was noticed. To our knowledge, this is the first report of a case of hemisacral reconstruction using a custom-made 3D-printed implant. We believe that this technique can be applied to spinal reconstructions after a partial or complete spondylectomy in a wide variety of spinal diseases.

Compression Angle of Ossification of the Posterior Longitudinal Ligament and Its Clinical Significance in Cervical Myelopathy

OBJECTIVES: The correction of clinical and radiologic abnormalities in patients with symptomatic ossification of the posterior longitudinal ligament (OPLL) is the current mainstay of treatment. This study aimed to identify radiographic predictors of severity of myelopathy in patients with symptomatic OPLL. METHODS: Fifty patients with symptomatic cervical OPLL were enrolled. Based on Japanese Orthopedic Association (JOA) scores, patients were divided into either the mild myelopathy (n=31) or severe myelopathy (n=19) group. All subjects underwent preoperative plain cervical roentgenogram, computed tomography (CT), and MR imaging (MRI). Radiological parameters (C2–7 sagittal vertical axis, SVA; C2–7 Cobb angle; C2–7 range of motion, ROM; OPLL occupying ratio; and compression angle) were compared. Compression angle of OPLL was defined as the angle between the cranial and caudal surfaces of OPLL at the maximum level of cord compression RESULTS: The occupying ratio of the spinal canal, C2–7 Cobb angle, C2–7 SVA, types of OPLL, and C2–7 ROM of the cervical spine were not statistically different between the two groups. However, the OPLL compression angle was significantly greater (p=0.003) in the severe myelopathy group than in the mild myelopathy group and was inversely correlated with JOA score (r=-0.533, p<0.01). Furthermore, multivariate regression analysis demonstrated that the compression angle (B=-0.069, p<0.001) was significantly associated with JOA scores (R=0.647, p<0.005). CONCLUSION: Higher compression angles of OPLL have deleterious effects on the spinal cord and decrease preoperative JOA scores.

A Gene and Neural Stem Cell Therapy Platform Based on Neuronal Cell Type-Inducible Gene Overexpression

PURPOSE: Spinal cord injury (SCI) is associated with permanent neurological damage, and treatment thereof with a single modality often does not provide sufficient therapeutic outcomes. Therefore, a strategy that combines two or more techniques might show better therapeutic effects. MATERIALS AND METHODS: In this study, we designed a combined treatment strategy based on neural stem cells (NSCs) introduced via a neuronal cell type-inducible transgene expression system (NSE::) controlled by a neuron-specific enolase (NSE) promoter to maximize therapeutic efficiency and neuronal differentiation. The luciferase gene was chosen to confirm whether this combined system was working properly prior to using a therapeutic gene. The luciferase expression levels of NSCs introduced via the neuronal cell type-inducible luciferase expression system (NSE::Luci) or via a general luciferase expressing system (SV::Luci) were measured and compared in vitro and in vivo. RESULTS: NSCs introduced via the neuronal cell type-inducible luciferase expressing system (NSE::Luci-NSCs) showed a high level of luciferase expression, compared to NSCs introduced via a general luciferase expressing system (SV::Luci-NSCs). Interestingly, the luciferase expression level of NSE::Luci-NSCs increased greatly after differentiation into neurons. CONCLUSION: We demonstrated that a neuronal cell type-inducible gene expression system is suitable for introducing NSCs in combined treatment strategies. We suggest that the proposed strategy may be a promising tool for the treatment of neurodegenerative disorders, including SCI.

The Use of Magnetic Resonance Imaging in Predicting the Clinical Outcome of Spinal Arteriovenous Fistula

PURPOSE: Magnetic resonance imaging (MRI) has been used to screen and follow-up spinal dural arteriovenous fistulae (SDAVF). The purpose of this study was to evaluate the association between MRI findings and neurologic function in SDAVF. This study also investigated clinical features and treatment results of SDAVF. MATERIALS AND METHODS: A total of 15 consecutive patients who underwent embolization or surgery for SDAVF were included. We treated seven (60%) patients with embolization and six (40%) with surgery. We analysed clinical features, MRI findings, treatment results, and neurologic function. Neurologic function was measured by the Aminoff-Logue disability scale (ALS). RESULTS: Patients with longer levels of intramedullary high signal intensity in preoperative T2-weighted images (T2WI) exhibited worse pre- and postoperative ALS scores (r=0.557, p=0.031; r=0.530, p=0.042, Pearson correlation). Preoperative ALS score was significantly correlated with postoperative ALS score (r=0.908, p=0.000, Pearson correlation). The number of levels showing intramedullary high signal intensity in T2WI decreased significantly postoperatively (5.2+/-3.1 vs. 1.0+/-1.4, p=0.001, Wilcoxon ranked test). CONCLUSION: The number of involved levels of high signal intensity in preoperative T2WI is useful for predicting pre- and postoperative neurologic function in SDAVF.

The Use of Magnetic Resonance Imaging in Predicting the Clinical Outcome of Spinal Arteriovenous Fistula

PURPOSE: Magnetic resonance imaging (MRI) has been used to screen and follow-up spinal dural arteriovenous fistulae (SDAVF). The purpose of this study was to evaluate the association between MRI findings and neurologic function in SDAVF. This study also investigated clinical features and treatment results of SDAVF. MATERIALS AND METHODS: A total of 15 consecutive patients who underwent embolization or surgery for SDAVF were included. We treated seven (60%) patients with embolization and six (40%) with surgery. We analysed clinical features, MRI findings, treatment results, and neurologic function. Neurologic function was measured by the Aminoff-Logue disability scale (ALS). RESULTS: Patients with longer levels of intramedullary high signal intensity in preoperative T2-weighted images (T2WI) exhibited worse pre- and postoperative ALS scores (r=0.557, p=0.031; r=0.530, p=0.042, Pearson correlation). Preoperative ALS score was significantly correlated with postoperative ALS score (r=0.908, p=0.000, Pearson correlation). The number of levels showing intramedullary high signal intensity in T2WI decreased significantly postoperatively (5.2+/-3.1 vs. 1.0+/-1.4, p=0.001, Wilcoxon ranked test). CONCLUSION: The number of involved levels of high signal intensity in preoperative T2WI is useful for predicting pre- and postoperative neurologic function in SDAVF.

Three Cases of Spine Fractures after an Airplane Crash / 대한신경손상학회지

While injuries to the spine after an airplane crash are not rare, most crashes result in fatal injuries. As such, few studies exist that reported on spine fractures sustained during airplane accidents. In this report, we demonstrate three cases of spine fractures due to crash landing of a commercial airplane. Three passengers perished from injuries after the crash landing, yet most of the passengers and crew on board survived, with injuries ranging from minor to severe. Through evaluating our three spine fracture patients, it was determined that compression fracture of the spine was the primary injury related to the airplane accident. The first patient was a 20-year-old female who sustained a T6-8 compression fracture without neurologic deterioration. The second patient was a 33-year-old female with an L2 compression fracture, and the last patient was a 49-year-old male patient with a T8 compression fracture. All three patients were managed conservatively and required spinal orthotics. During the crash, each of these patients were subjected to direct, downward high gravity z-axis (Gz) force, which gave rise to load on the spine vertically, thereby causing compression fracture. Therefore, new safety methods should be developed to prevent excessive Gz force during airplane crash landings.

Use of Annular Closure Device (Barricaid(R)) for Preventing Lumbar Disc Reherniation: One-Year Results of Three Cases / 대한신경손상학회지

Although lumbar discectomy is an effective treatment for lumbar disc herniation, complications exist, including postoperative disc height loss, facet joint degeneration, and recurrent disc herniation. To solve these problems, annular closure devices have been utilized in other countries, producing satisfactory results, but there has been no report of annular closure device use in our country. Here, we demonstrate the preliminary reports of Barricaid(R) insertion in 3 patients who underwent surgery for lumbar disc herniation.

Rosai-Dorfman Disease in Thoracic Spine: A Rare Case of Compression Fracture

Sinus histiocytosis with massive lymphadenopathy known as Rosai-Dorfman disease is characterized by painless bilateral cervical lymphadenopathy. Extranodal manifestations are uncommon and spinal involvement is rare. A 15-year-old man presented with intermittent midthoracic back pain only. He had no specific findings on neurologic examinations, hematologic and biochemical laboratory tests. Radiological examination of thoracic spine revealed collapse of T6 vertebrae with thoracic kyphosis and osteolytic lesion of T12 vertebra body. He underwent a removal of bone tumor, anterior reconstruction with mesh and pedicle screw fixation via posterior approach for pathologic confirmation and stabilization. Histopathologic study of the lesion revealed focal infiltration of large histiocytes showing emperipolesis. Immunochemistry stain of histiocytes was positive for CD68 and S-100 but negative for CD1a. This report presents a rare case and literature review of extranodal Rosai-dorfman disease in thoracic spine.

Spinal Cord Hemangioblastomas in von Hippel-Lindau Disease: Management of Asymptomatic and Symptomatic Tumors

PURPOSE: Standard treatment of asymptomatic spinal cord hemangioblastoma in von Hippel-Lindau (VHL) disease has yet to be established. The purpose of this study was to propose guidelines for the treatment of asymptomatic spinal cord hemangioblastomas in VHL disease. MATERIALS AND METHODS: VHL disease patients treated for spinal cord hemangioblastomas between 1999 and 2009 were included. All spinal cord hemangioblastomas were divided into three groups: Group 1, asymptomatic tumors at initial diagnosis followed with serial imaging studies; Group 2, asymptomatic tumors at initial diagnosis that were subsequently resected; and Group 3, symptomatic tumors at initial diagnosis, all of which were resected. RESULTS: We identified 24 spinal cord hemangioblastomas in 12 patients. Groups 1, 2 and 3 comprised 13, 4 and 7 tumors, respectively. Group 1 exhibited a smaller tumor volume (257.1 mm3) and syrinx size (0.8 vertebral columns) than those of Group 2 (1304.5 mm3, 3.3 vertebral columns) and Group 3 (1787.4 mm3, 6.1 vertebral columns). No difference in tumor volume or syrinx size was observed between Groups 2 and 3. Five tumors in Group 1 were resected during follow-up because symptoms had developed or the tumor had significantly grown. Finally, among 17 asymptomatic tumors at the initial diagnosis, nine tumors were resected. Only one tumor of these nine tumors resulted in neurological deficits, while five of seven symptomatic tumors caused neurological deficits. CONCLUSION: Selective resection of asymptomatic tumors before they cause neurological deficits might bring about better outcomes.

Initial Clinical Outcomes of Minimally Invasive Lateral Lumbar Interbody Fusion in Degenerative Lumbar Disease: A Preliminary Report on the Experience of a Single Institution with 30 Cases

OBJECTIVE: The object of this study was to evaluate the clinical and radiological outcomes of minimally invasive lateral lumbar interbody fusion. METHODS: This study included 30 patients who underwent minimally invasive lateral lumbar interbody fusion at our hospital between May 2011 and February 2012 for the following diagnoses: degenerative disc disease, adjacent-segment degeneration, degenerative spondylolisthesis and lumbar degenerative scoliosis. Pain assessment was reported from 0 to 10 using a subjective visual analog scale (VAS) upon admission and at every follow-up day. Lumbar X-rays were obtained in the standing position upon admission and the 1st and 5th postoperative day, and at every follow-up day after the operation. The heights of the intervertebral disc space and neural foramen were measured using an electronic caliper with the PACS software. The surgical outcome was assessed as excellent, good, fair or poor using the Odom scale at the last follow-up. RESULTS: The mean VAS for low back pain were 4.93+/-1.47 on admission and 2.01+/-1.35 at last follow-up, respectively, and for leg pain, the scores were 4.87+/-2.16 on admission and 1.58+/-1.52 at last follow-up. The mean height of intervertebral disc space increased by 34% (7.93+/-2.33 preoperatively, and 11.09+/-4.33 immediately after surgery, p<0.01). The mean height of neural foramen also increased by 6.4% without any statistical significance (19.17+/-2.84 preoperatively, and 20.49+/-4.50 immediately after the surgery). Minimally invasive lateral lumbar interbody fusion was successful in 27 patients (90%) at last follow-up. Surgical complications were reported as transient postoperative thigh sensory changes (5 patients, 16.7%), transient psoas muscle weakness (3 patients, 10%), cage migration (2 patients, 6.7%), lumbar plexus injury (1 patient, 3.3%), and pain aggravation (1 patient, 3.3%). CONCLUSION: The minimally invasive lateral lumbar interbody fusion is a safe and effective procedure for treating degenerative lumbar disease with good outcomes and moderate complications. Further follow-up is necessary to establish its safety and efficacy.

Correction of Coronal Imbalance in Degenerative Lumbar Spine Disease Following Direct Lateral Interbody Fusion (DLIF)

OBJECTIVE: The authors have recently been using a surgical technique of minimally invasive direct lateral interbody fusion (DLIF) for correcting of coronal imbalance. The purpose of this study was to evaluate the surgical outcome and complication of DLIF. METHODS: We undertook retrospective analysis of a consecutive series of 8 DLIF procedures in Degenerative lumbar spine disease since May 2011. Four patients underwent DLIF only, and the others underwent combined DLIF and posterior fixation. Data on intra- and postoperative complications were collected. The pre- and postoperative X-rays were reviewed. We investigated coronal deformity, Cobb's angle, and apical vertebral translation (AVT). The mean follow-up period was months with a range of 2 to 8 months. RESULTS: A mean preoperative coronal Cobb's angle was 21.8degrees (range 11.5-32.4degrees). Following after DLIF, the mean Cobb's angle was decreased to 13.0degrees (range 2.9-21.5degrees). Following additional posterior screw fixation, mean Cobb's angle was further decreased to 7.4degrees (range 2.9-13.2degrees). A mean preoperative AVT was 2.0 cm(range 0.6-3.5 cm), and improved to 1.4 cm(range 0.3-2.4 cm) and 0.8 cm(range 0.2-1.8 cm) postoperatively (DLIF and, posterior fixation respectively). One patient (12.5%) showed cage migration during follow-up period. Two patients (25%) developed motor weakness, and 4 patients (50%) experienced postoperative thigh paresthesias or dysesthesias. During follow up period, motor weakness had resolved in 1 patient. Sensory symptoms were improved in all patients at the last follow-up. CONCLUSION: Degenerative lumbar disease can be effectively corrected by DLIF with acceptable complications.

Surgical Outcomes of Spine Disorders in Patients with Parkinson's Disease

PURPOSE: Patients with Parkinson's disease also commonly have movement disorders, osteoporosis, and other comorbidities. These patients are more likely to have complications after spinal surgery. The aim of the present study is to show the relation ship between complications of spinal surgery and Parkinson's disease. METHODS: A computerized search using diagnostic and procedural codes identified 13 patients with Parkinson's disease who underwent spinal surgery between January 1998 and December 2010. Their medical records and imaging studies were reviewed and recent updatesfor all patients were done by telephone interview. RESULTS: Retrospectively, 13 consecutive patients were reviewed. The mean age was 63.8 (range 44~87) years old and the mean durationof Parkinson's disease was 7.6 (range 1~22) years at the time of the index procedure. The mean T score of the lumbar spine on Dual-energy X-ray absorptiometry (DEXA) scan bone mineral density (BMD) was -2.5 (range -1.0~-5.1). These patients had nine lumbar lesions, two thoracic lesions, one cervical lesion, and one thoracolumbar lesion. Nine patients required no more surgical treatment for lesions which had been previously operated on (index level). However, four patients (30.8%) needed at least one more operation related to their index procedure; segmental degeneration on the adjacent levels in two, retropulsion of an intervertebral cage with screw loosening in one, and pedicle fracture in one. CONCLUSION: It has been reported that patients with Parkinson's disease have high complication rates in spinal surgery. Spine surgeons should be aware of the risk of complications and need to conduct careful follow-up after the surgery.

Comparison of the Outcomes after Intralesional, Intracisternal, and Intravenous Transplantation of Human Bone Marrow Derived Mesenchymal Stem Cells for Spinal Cord Injured Rat

OBJECTIVE: Mesenchymal stem cells (MSCs) have shown promise in potentially repairing injured spinal cord. These and similar cell types are being tested clinically, but the understanding about delivering method and subsequent results is lacking. This study was designed to compare the MSCs engraftment results after intralesional, intracisternal, or intravenous injection in a rat with spinal cord injury (SCI). METHODS: A total of 48 male Sprague-Dawley rats (300-350 g in size) were used with 12 in each group. Allogenic MSCs were cultured from human bone marrow aspirates. The SCI was induced using an NYU (New York University) impactor and MSCs were transplanted 1 week after the SCI. Behavioral testing was performed weekly for 6 weeks. The recipients were analyzed histologically to evaluate the extent of cell delivery and survival at the injury site. RESULTS: All three experimental groups showed better behavioral recovery compared with the control group since 6 weeks after stem cell injection (p<0.05). The intracisternal injection group showed the best functional improvement (p<0.05). The intralesional injection group showed the best engraftment until 4 weeks after stem cell injection (p<0.05). A number of the injected MSCs were trapped in the spleen in the intravenous injection group. CONCLUSION: Transplantation of stem cells by a variety of routes can deliver cells with the potential to repair injured spinal cord. Intracisternal injection can easily be translated to patients after some modifications, thus accelerating clinical application of cell therapies.

Robot-Assisted Transoral Odontoidectomy : Experiment in New Minimally Invasive Technology, a Cadaveric Study

OBJECTIVE: In the field of spinal surgery, a few laboratory results or clinical cases about robotic spinal surgery have been reported. In vivo trials and development of related surgical instruments for spinal surgery are required before its clinical application. We investigated the use of the da Vinci(R) Surgical System in spinal surgery at the craniovertebral junction in a human cadaver to demonstrate the efficacy and pitfalls of robotic surgery. METHODS: Dissection of pharyngeal wall to the exposure of C1 and odontoid process was performed with full robotic procedure. Although assistance of another surgeon was necessary for drilling and removal of odontoid process due to the lack of appropriate end-effectors, successful robotic procedures for dural sutures and exposing spinal cord proved its safety and dexterity. RESULTS: Robot-assisted odontoidectomy was successfully performed in a human cadaver using the da Vinci(R) Surgical System with few robotic arm collisions and minimal soft tissue damages. Da Vinci(R) Surgical System manifested more dexterous movement than human hands in the deep and narrow oral cavity. Furthermore, sutures with robotic procedure in the oral cavity demonstrated the advantage over conventional procedure. CONCLUSION: Presenting cadaveric study proved the probability of robot-assisted transoral approach. However, the development of robotic instruments specific to spinal surgery must first precede its clinical application.

Robot-assisted Resection of Paraspinal Schwannoma

Resection of retroperitoneal tumors is usually perfomed using the anterior retroperitoneal approach. Our report presents an innovative method utilizing a robotic surgical system. A 50-yr-old male patient visited our hospital due to a known paravertebral mass. Magnetic resonance imaging showed a well-encapsulated mass slightly abutting the abdominal aorta and left psoas muscle at the L4-L5 level. The tumor seemed to be originated from the prevertebral sympathetic plexus or lumbosacral trunk and contained traversing vessels around the tumor capsule. A full-time robotic transperitoneal tumor resection was performed. Three trocars were used for the robotic camera and working arms. The da Vinci Surgical System(R) provided delicate dissection in the small space and the tumor was completely removed without damage to the surrounding organs and great vessels. This case demonstrates the feasibility of robotic resection in retroperitoneal space. Robotic surgery offered less invasiveness in contrast to conventional open surgery.

Spontaneous Atlantoaxial Subluxation due to Pyogenic or Tuberculosis Vertebral Osteomyelitis: Diagnosis and Treatment

OBJECTIVE: The purpose of this study is to evaluate the clinical and radiographic results of infective atlantoaxial subluxation, and to describe the management of pyogenic or tuberculosis atlantoaxial subluxation. METHODS: In this study, we present seven patients with atlantoaxial subluxation after pyogenic or tuberculosis vertebral osteomyelitis. Prominent manifestations included neck pain and stiffness, swelling of the retropharyngeal soft tissues, quadriparesis, and osteolytic erosions. All patients received antibiotics/antituberculosis medication. One patient was managed conservatively, two underwent only transoral biopsy, one patient underwent transoral decompression and posterior fusion, and three patients underwent only posterior fusion. RESULTS: All patients showed significant improvement in neck pain and neck movement. Three patients who showed quadriparesis or motor weakness at the time of diagnosis showed improvement in motor strength, although subjective weakness persisted in two patients. CONCLUSION: In our study, we describe the management of this disease at our institute. Available treatment modalities vary from purely conservative medical management to surgical correction. Medical treatment is the mainstay of management. The need for and the extent of surgery are dependent on the presence of instability and spinal cord compression and should be determined on a case by case basis.

Two Separate Episodes of Intramedullary Spinal Cord Metastasis in a Single Patient with Breast Cancer

Intramedullary spinal cord metastases are very rare. Patients with breast cancer as the primary source of intramedullary spinal cord metastases tend to do better than other types of cancer. We report the very unusual case of a woman with breast cancer who had two separate episodes of intramedullary spinal cord metastasis.