Minimally Invasive Surgery Transpedicular Intrabody Cage Technique for the Management of Kummell Disease.

BACKGROUND: The treatment of Kummell disease remains controversial, with a wide variety of options proposed in the literature. This study aims to introduce a unique and minimally invasive approach for the treatment of Kummell disease and present the clinical results of this technique. METHODS: Twenty patients underwent surgery using the minimally invasive surgery transpedicular intrabody cage (MISTIC) technique from 2014 to 2016. Postoperatively, patients were seen at 3, 6, and 12 months after surgery. Visual analog scale and Oswestry Disability Index scores were collected, and patient outcomes were graded according to the modified MacNab's criteria. Radiological outcomes were assessed through measurements of the anterior vertebral height (AH), mean vertebral body height (BH), and segmental angle (SA) on standing lateral radiographs pre- and postoperatively. RESULTS: There was significant improvement in the SA, AH, and BH postoperatively. The SA improved from 15.2 ± 8.7° of kyphosis to 1.2 ± 5.2° (P < 0.01) in the immediate postoperative period. The AH increased from 13.3 ± 14.6 to 22.6 ± 12.2 mm (P < 0.01), and at the final follow-up, it was 21.9 ± 12.6 mm (P < 0.01). Similarly, the BH increased from 18.5 ± 6.8 to 25.6 ± 7.6 mm (P < 0.01) postsurgery, and at the final follow-up, it was 23.6 ± 4.4 mm (P < 0.01). CONCLUSIONS: The MISTIC technique offers significant correction of kyphosis and restoration of the vertebral anatomy following surgery. These results were maintained at 12 months postoperation, with a 100% union rate of the fractures. Additionally, patients experienced significant pain relief and improvement in their ODI scores that were maintained at 12 months.

Subaxial Cervical Pedicle Screw in Traumatic Spinal Surgery.

In cases of unstable cervical traumatic lesions, the biomechanical superiority of the cervical pedicle screw (CPS) allows the lesion to be stabilized effectively. In this study, we review and summarize the indications, technical guidelines, and potential neurovascular complications and their prevention of the use of the CPS for trauma. For patients with fractured lamina or lateral mass, a CPS is reliable for stabilization. In addition, the CPS can penetrate through a linear cervical spinal pedicle fracture gap and could stabilize three-column injury. CPS reduce the range of surgical approach and preserve the motion segment using short-segment fixation. Fluoroscopy-guided CPS insertion is popular and cost-effective. Image-guided navigation systems improve accuracy. Three-dimensional template-guided CPS placement is simple to use. Most spine surgeons can perform laminoforaminotomy easily. Freehand technique that can be performed quickly without heavy equipment is suitable for emergency situation. Possible complications due to screw misplacement are vertebral artery injury owing to a laterally misplaced screw, dural sac or spinal cord injury from a medially misplaced screw, and nerve root injury caused by a superiorly or inferiorly misplaced screw. To prevent neurovascular complications, meticulous preoperative anatomical evaluation and following the five steps are most important.

Comparison of the Accuracy of C1 Pedicle Screw Fixation Using Fluoroscopy and Free-Hand Techniques in Patients With Posterior Arch Thickness of Less Than 4 mm.

BACKGROUND: C1 pedicle screw insertion is not easy, and more fluoroscopy can be required for safe insertion. Fluoroscopy is time consuming and increases patient radiation exposure. There have been no studies comparing the accuracy of C1 pedicle screw insertion using the fluoroscopy and free-hand techniques. OBJECTIVE: To describe a free-hand C1 pedicle screw insertion method in patients with the posterior arch thickness of less than 4 mm in the thinnest part of the groove, and to compare the clinical and radiological outcomes of C1 pedicle screw insertion using fluoroscopy vs using the free-hand technique. METHODS: A total of 25 patients who had atlantoaxial instability with a C1 posterior arch <4 mm and were treated with C1 pedicle screw insertion were included. In 10 patients, fluoroscopy was used for C1 pedicle screw insertion, and 15 patients underwent the free-hand technique. We compared the radiologic and clinical outcomes between the 2 groups. RESULTS: In patients who underwent the free-hand technique, 96.5% of screws were rated as safe (grade A or B), and 80.0% of screws in the fluoroscopy group were rated as safe. Postoperative occipital neuralgia occurred in one patient in the fluoroscopy group and did not occur in the free-hand technique group. There was no significant difference in the improvement of Nurick grade between the 2 groups. CONCLUSION: C1 pedicle screw insertion using the free-hand technique is feasible and safe in patients with a C1 posterior arch <4 mm.

The Subaxial Cervical Pedicle Screw for Cervical Spine Diseases: The Review of Technical Developments and Complication Avoidance.

This study aimed to review information on the subaxial cervical pedicle screw (CPS) including recent anatomical considerations, entry points, placement techniques, accuracy, learning curve, and complications. Relevant literatures were reviewed, and the authors' experiences were summarized. The CPS is used for reconstruction of unstable cervical spine and achieves superior biomechanical stability compared to other fixation techniques. Various insertion and guidance techniques are established, among which, lateral fluoroscopy-assisted placement is the most common and cost-effective technique. Generally, placement under imaging guidance is more accurate than other techniques, and a three-dimensional template allows optimal trajectory for each pedicle regardless of intraoperative changes in spinal alignment. The free-hand technique using a curved pedicle probe without a funnel-like hole increases screw stability and reduces operation time, radiation exposure, and soft tissue injury. Compared to conventional lateral fluoroscopy-assisted placement, free-hand CPS placement by trained surgeons achieves superior accuracy comparable to that of image-guided navigation; in general, 30 training cases are sufficient for learning a safe and accurate technique for CPS placement. The complications of subaxial CPS are classified into three categories: complications due to screw misplacement, complications without screw misplacement, and others. Inexperienced surgeons may benefit from advanced techniques; however, the accuracy of CPS ultimately depends on the surgeon's experience. Inexperienced surgeons should master the placement of the thoracolumbar pedicle screw in real practice and practice CPS insertion using cadavers. During the initial phase of the learning curve, careful preparation of surgery, reiterated identification, patterned safety steps, and supervision of the expert are necessary.

Current Status and Future Strategies to Treat Spinal Cord Injury with Adult Stem Cells.

Spinal cord injury (SCI) is one of the most devastating conditions and many SCI patients suffer neurological sequelae. Stem cell therapies are expected to be beneficial for many patients with central nervous system injuries, including SCI. Adult stem cells (ASCs) are not associated with the risks which embryonic stem cells have such as malignant transformation, or ethical problems, and can be obtained relatively easily. Consequently, many researchers are currently studying the effects of ASCs in clinical trials. The environment of transplanted cells applied in the injured spinal cord differs between the phases of SCI; therefore, many researchers have investigated these phases to determine the optimal time window for stem cell therapy in animals. In addition, the results of clinical trials should be evaluated according to the phase in which stem cells are transplanted. In general, the subacute phase is considered to be optimal for stem cell transplantation. Among various candidates of transplantable ASCs, mesenchymal stem cells (MSCs) are most widely studied due to their clinical safety. MSCs are also less immunogenic than neural stem/progenitor cells and consequently immunosuppressants are rarely required. Attempts have been made to enhance the effects of stem cells using scaffolds, trophic factors, cytokines, and other drugs in animal and/or human clinical studies. Over the past decade, several clinical trials have suggested that transplantation of MSCs into the injured spinal cord elicits therapeutic effects on SCI and is safe; however, the clinical effects are limited at present. Therefore, new therapeutic agents, such as genetically enhanced stem cells which effectively secrete neurotrophic factors or cytokines, must be developed based on the safety of pure MSCs.

Quantitative analysis of background parenchymal enhancement in whole breast on MRI: Influence of menstrual cycle and comparison with a qualitative analysis.

OBJECTIVE: We quantitatively analyzed background parenchymal enhancement (BPE) in whole breast according to menstrual cycle and compared it with a qualitative analysis method. MATERIALS AND METHODS: A data set of breast magnetic resonance imaging (MRI) from 273 breast cancer patients was used. For quantitative analysis, we used semiautomated in-house software with MATLAB. From each voxel of whole breast, the software calculated BPE using following equation: [(signal intensity [SI] at 1 min 30 s after contrast injection - baseline SI)/baseline SI] × 100%. RESULTS: In total, 53 patients had minimal, 108 mild, 87 moderate, and 25 marked BPE. On quantitative analysis, mean BPE values were 33.1% in the minimal, 42.1% in the mild, 59.1% in the moderate, and 81.9% in the marked BPE group showing significant difference (p = .009 for minimal vs. mild, p < 0.001 for other comparisons). Spearman's correlation test showed that there was strong significant correlation between qualitative and quantitative BPE (r = 0.63, p < 0.001). The mean BPE value was 48.7% for patients in the first week of the menstrual cycle, 43.5% in the second week, 49% in the third week, and 49.4% for those in the fourth week. The difference between the second and fourth weeks was significant (p = .005). Median, 90th percentile, and 10th percentile values were also significantly different between the second and fourth weeks but not different in other comparisons (first vs. second, first vs. third, first vs. fourth, second vs. third, or third vs. fourth). CONCLUSION: Quantitative analysis of BPE correlated well with the qualitative BPE grade. Quantitative BPE values were lowest in the second week and highest in the fourth week.

A suggestion of modified classification of trigeminal schwannomas according to location, shape, and extension.

BACKGROUND: Comprehensive knowledge of the anatomical features of trigeminal schwannomas (TSs) is essential in planning surgery to achieve complete tumor resection. In the current report, we propose a modified classification of TSs according to their location of origin, shape, and extension into the adjacent compartment, and discuss appropriate surgical strategies with this classification. METHODS: We retrospectively analyzed 49 patients with TS who were treated surgically by a single neurosurgeon at the Asan Medical Center between 1993 and 2013. RESULTS: There were 22 males and 27 females, with the median age of 40 years (range, 21-75 years). Median tumor size was 4.0 cm in diameter (2.0-7.0 cm). Tumors were classified as follows: Type M (confined to the middle fossa; 8 cases, 19.0%), P (confined to the posterior fossa; 2 cases, 4.8%), MP (involving equally both middle and posterior fossae; 5 cases, 11.9%), Mp (predominantly middle fossa with posterior fossa extension; 6 cases, 14.3%), Pm (predominantly posterior fossa with middle fossa extension; 16 cases, 38.1%), Me (predominantly middle fossa with extracranial extension; 4 cases, 9.5%). Surgical approach was chosen depending on the tumor classification. More specifically, a frontotemporal craniotomy and extradural approach with or without zygomatic or orbitozygomatic osteotomy was applied to M- or Mp-type tumors; a lateral suboccipital craniotomy with or without suprameatal approach was applied to the majority of P- or Pm-type tumors; and a posterior transpetrosal approach was used in four tumors (three Pm and one MP). Gross total resection was achieved in 95.9% of patients, and the overall recurrence rate was 4.1% (2 patients). Postoperatively, trigeminal symptoms were improved or unchanged in 51.0% of cases (25 patients). Surgical complications included meningitis (5 patients) and cerebrospinal fluid leakage (3 patients). There was no mortality. CONCLUSION: TSs are well to be classified with our modified classification and able to be removed effectively and safely by selecting appropriate surgical approaches.

Extra-intradural Spinal Meningioma: A Case Report.

Extradural spinal meningiomas are uncommon, and their pathophysiology is not entirely understood. Here, we present the case of a 49-year-old woman with low back and left leg pain of 5 years duration. Magnetic resonance imaging revealed a mass, 1.8-cm in size, with rim enhancement in the spinal canal at the T12 level and extending into the left T12-L1 foramen. In the surgical field, the mass presented with the characteristics of an extra-intradural spinal meningioma. The patient underwent a T12 total laminectomy. A linear durotomy was performed at the midline, and the intradural portion was removed. The extradural portion was not separable from the adjacent dura and the left T12 root, and it was removed by dural excision. Pathological examination confirmed the diagnosis of psammomatous meningioma. We also conducted a literature review of similar cases. Based on our experience with this case, we believe that it is important to clearly distinguish extradural meningiomas from other types of tumors as misdiagnosis can change the operative plan. The long term prognosis of extradural meningiomas is not clear but total excision is thought to be essential.

Neural network modeling of deposition rate characteristics of low temperature silicon nitride deposited by inner two parallel coil inductively coupled plasma chemical vapor deposition.

In this study, a neural network model for silicon nitride (SiN) deposition process is proposed. SiN thin films were deposited by a direct inner two parallel inductively coupled plasma chemical vapor deposition (ICPCVD) system that can control the activated radical and charged species in plasma. This system can produce SiN thin films at low temperature for flexible displays. The input parameters considered for deposition conditions were the N2 gas flow rate, NH3 gas flow rate, and substrate temperature. These were varied within the ranges of 0-20 sccm, 0-20 sccm, and 100-300 degrees C, respectively. For those of input parameters and the output of deposition rate, we developed a back propagation neural network model with a pre-processor. It is shown that the model accuracy and learning speed of the proposed model are better than those of a conventional neural network model. In the experiments conducted, it was found that the deposition rate increased as the flow rates of ammonia (NH3) and nitrogen (N2) increased up to a certain amount. On the contrary, when the flow rates of NH3 and N2 went over a certain amount, the deposition rate decreased. It was also found that an increase in temperature resulted in an increase in the deposition rate.