Intraoperative Cone-Beam Computed Tomography Assessment of Spinal Pedicle Screws Placement Precision Is in Full Agreement with Postoperative Computed Tomography Assessment.

OBJECTIVE: To assess agreement between pedicle screw placement evaluated on postoperative computed tomography (CT) and on intraoperative cone-beam CT (CBCT) and compare procedure characteristics when using first-generation and second-generation robotic C-arm systems in the hybrid operating room. METHODS: All patients who received pedicle screws for spinal fusion at our institution between June 2009 and September 2019 and underwent intraoperative CBCT and postoperative CT were included. The CBCT and CT images were reviewed by 2 surgeons to assess the screw placement using the Gertzbein-Robbins and the Heary classifications. Intermethod agreement of screw placement classifications as well as interrater agreement were assessed using Brennan-Prediger and Gwet agreement coefficients. Procedure characteristics using first-generation and second-generation generation robotic C-arm systems were compared. RESULTS: Fifty-seven patients were treated with 315 pedicle screws at thoracic, lumbar, and sacral levels. No screw had to be repositioned. On CBCT, accurate placement was found for 309 screws (98.1%) using the Gertzbein-Robbins classification and 289 (91.7%) using the Heary classification and on CT, these were 307 (97.4%) and 293 (93.0%), respectively. Intermethod between CBCT and CT and interrater agreements between the 2 raters were almost perfect (>0.90) for all assessment. There were no significant differences in mean radiation dose (P = 0.83) and fluoroscopy time (P = 0.82), but length of surgery using the second-generation system was estimated at 107.7 minutes (95% confidence interval, 31.9-183.5 minutes; P = 0.006) shorter. CONCLUSIONS: Intraoperative CBCT provides accurate assessment of pedicle screw placement and enables intraoperative repositioning of misplaced screws.

Preoperative assessment of dominant occipital sinus in patients with Chiari malformation type I: anatomical variations and implications for preventing potentially life-threatening surgical complications.

OBJECTIVE: The surgical treatment of Chiari malformation type I (CM-I) frequently involves dural incision at the posterior cranial fossa. In cases of persistent patent occipital sinus (OS), the sinus is usually obliterated and divided. However, there are some patients whose OS is prominent and requires crucial modification of the operative planning to avoid potentially life-threatening massive hemorrhage and disturbance of cerebral venous circulation. In the present study, the anatomical variations of the dominant OS in patients with CM-I were analyzed and the authors attempted to develop treatment recommendations for patients with CM-I with dominant OS. METHODS: The study included 213 patients with CM-I who underwent MR venography (MRV) prior to surgical treatment. OS dominance was assessed using 2D time-of-flight MRV or 3D phase-contrast MRV. Particular attention was paid to the pattern of venous outflow channels. The characteristics of the patients with dominant OS and the surgical outcomes were retrospectively reviewed. RESULTS: Dominant OS was identified in 7 patients (3.3%). The age in those with dominant OS was significantly younger than in those without (p = 0.0202). The incidence of concurrent scoliosis in the patients with dominant OS was significantly higher than in those without (p = 0.0366). All the dominant OSs were found to be of the oblique type. Unilateral oblique OS (OOS) with normal ipsilateral transverse sinus (TS) and hypoplastic contralateral TS was found in 2 patients (0.9%). The authors found 1 patient each (0.5%) who had unilateral OOS with hypoplastic ipsilateral TS and normal contralateral TS, unilateral OOS with bilateral hypoplastic TSs, and bilateral OOSs with bilateral normal TSs. Bilateral OOSs with bilateral hypoplastic TSs were found in 2 patients (0.9%). All these patients had syringomyelia. Instead of performing Y-shaped dural incision and duraplasty, surgical procedures were modified depending on the types of the OOSs to preserve their venous drainage routes. Although massive bleeding from the dominant OS during dural incision occurred in 1 patient, none suffered neurological deterioration. The syrinx volume decreased in all but 1 of the patients postoperatively. CONCLUSIONS: Assessment of the venous drainage pattern using MRV is indispensable for safe surgical treatment in patients with CM-I. The surgical procedure should be modified based on the type of dominant OS to minimize the surgical risks.

MRI characteristics of syringomyelia associated with foramen magnum arachnoiditis: differentiation from Chiari malformation.

BACKGROUND: It is important to distinguish foramen magnum arachnoiditis (FMA) from Chiari malformation (CM) before surgery because the operative strategies for these diseases differ. In the current study, we compared pretreatment magnetic resonance imaging (MRI) of FMA with CM and investigated the MRI findings useful to differentiate between these diseases. METHODS: We retrospectively reviewed patients with FMA or CM aged ≥ 18 years who underwent surgeries at our institution between 2007 and 2019. The morphologies of the syrinx, neural elements, and posterior cranial fossa were preoperatively evaluated with MRI. We used the receiver operating characteristic (ROC) curve for the fourth ventricle-to-syrinx distance (FVSD). RESULTS: Ten patients with FMAs and 179 with CMs were included. FVSD in the FMA group was significantly shorter than that in the CM group (7.5 mm [IQR, 2.8-10 mm] in FMA vs. 29.9 mm [IQR, 16.3-52.9 mm] in CM, p < 0.0001). The other MRI findings that showed the height, size, and length of the syrinx; size of the foramen magnum; degree of cerebellar tonsillar descent; shape of the cerebellar tonsil; and dorsal subarachnoid space at the foramen magnum differed significantly between the two groups. The ROC curve analysis showed that patients whose FVSD was less than 11 mm could be diagnosed with FMA with a specificity of 90% and sensitivity of 96%. CONCLUSIONS: A more cranial syrinx development (FVSD < 11 mm) appears to be the characteristic MRI finding in FMA.

Significantly high concentrations of vascular endothelial growth factor in chronic subdural hematoma with trabecular formation.

The underlying mechanism of chronic subdural hematoma (CSDH) after minor head injury is complex, probably due to mechanical injury of the arachnoid membrane, hematological coagulopathy, and pathological angiogenesis in the dura caused by inflammatory cytokines including vascular endothelial growth factor (VEGF). To confirm whether VEGF might be a reliable predictive biomarker for the natural history of CSDH, including progression and recurrence, we analyzed the correlation of VEGF concentration in the subdural fluid with CT findings and clinical features, including interval from minor head injury. Based on CT classification by hematoma density, the mean concentration of VEGF in hematoma fluid was found to be highest in the trabecular group, whereas the recurrence of CSDH was most frequent in the separated group in which VEGF concentration was low. There was a significant correlation between VEGF concentration and the CT classification. Furthermore, only in the trabecular group, a significant negative correlation between the VEGF concentration and interval from minor head injury to surgery was observed. These results suggest that VEGF concentration in the hematoma alone could not be a reliable predictive biomarker for the natural history of CSDH including its recurrence. Amongst the classified groups of CSDH, the trabecular group is likely to follow a different time course of VEGF concentration in the hematoma fluid compared to the other three groups.

Alteration of FOXM1 expression and macrophage polarization in refractory meningiomas during long-term follow-up.

Malignant progression of grade I meningioma with a long latency period is rare. We experienced grade II/III meningiomas with refractoriness and recurrence from grade I meningiomas through multiple surgeries. Three patients with atypical/anaplastic meningioma experienced long-latent recurrence after initial surgery for grade I (meningothelial) meningioma without following adjuvant radiotherapy were included in the present study. Histological findings of the initial tumors in all cases (case 1, 2, and 3) revealed meningothelial meningioma with 1%, 5%, and 0.1% MIB-1 positive cells, respectively. Surprisingly, magnetic resonance imaging (MRI) detected a recurrent tumor 2, 12, and 12 years after the initial operation, respectively. Case 1 was atypical meningioma after third recurrence, and case 2 and 3 were anaplastic meningioma after second and third recurrence, respectively. The patient in case 2 received adjuvant radiotherapy. In case 2, the tumor recurred intracranial and distant metastasis to the lung with huge substantial pleural effusion was detected. To investigate the pathogenesis of malignant progression from benign to malignant meningioma, CD163/CD68 expression by immunohistochemically and FOXM1 mRNA expression by RT-PCR were compared using surgical specimens from initial and recurrent tumors in all three patients. The ratio of CD163/CD68 positivity and FOXM1 mRNA expression were increased in recurrent tumors compared with matched initial tumors. CD163 and FOXM1 expression levels were induced even in recurrent grade I meningioma, suggesting that macrophage polarization and pro-mitotic transcriptional factor might be associated with clinical behavior of meningioma and be useful as a prediction marker for malignant progression. Careful long-term follow-up is important for early diagnosis of malignant progression in meningiomas, even if grade I meningioma is completely resected. Development of a multidisciplinary approach including radiation and novel molecular targeted therapy is expected for recurrent and malignant meningiomas.

[Technical "Tips" for Epidural Tenting Using DuraGen® for Surgical Management of Large Dural Defects:A Technical Note].

DuraGen®, an absorbable, engineered collagen-based artificial graft was introduced in Japan in September 2019 for cranial, transsphenoidal, and spinal surgeries. In addition to its efficacy and safety profile, owing to sutureless dural repair, DuraGen® is widely accepted by neurosurgeons. Direct tenting with DuraGen® is occasionally required in patients with large dural defects, particularly in cases of tumors adherent to the dura. To overcome this limitation, we introduced a surgical technique for epidural tenting using DuraGen®. A 78-year-old man with a history of alexia underwent craniotomy for resection of a left temporal lobe metastatic tumor. We completely removed the recurrent tumor, which was strongly adherent to the dura in the middle cranial fossa. A layer of DuraGen® was used as a subdural underlay beneath the autologous dura to close the wide dural defect. To avoid postoperative epidural fluid collection, we retracted the DuraGen® from the epidural aspect and interposed several pieces of muscle, which were sutured on the subdural aspect to ensure that the muscle pieces securely plugged the dural defect. We placed an additional overlay of DuraGen® along the autologous dura. The patient's postoperative course was uneventful without cerebrospinal fluid leakage, tension pneumocephalus, or wound infection. Reoperations for tumor resection, particularly surgical procedures for refractory meningiomas and malignant tumors cause increasing fragility and wide defects of the dura. DuraGen® placement enables sutureless closure and is less time-consuming. Our technique of epidural direct tenting with DuraGen® using muscle pieces sutured on the subdural aspect could be useful in patients with significantly large dural defects and can prevent postoperative epidural fluid collection to ensure complete dural sealing.

Rapid Recurrence and Anaplastic Transformation of a Pilocytic Astrocytoma in an Elderly Patient: Case Report and Review of the Literature.

BACKGROUND: Rapid recurrence of a pilocytic astrocytoma with anaplastic transformation is extremely rare. The case of an elderly patient with a cerebellar pilocytic astrocytoma with anaplastic transformation during short-term follow-up is reported. CASE DESCRIPTION: An 83-year-old woman presented initially with dizziness and a gait deviation to the right. Magnetic resonance imaging demonstrated a homogeneously enhanced mass in the right cerebellar hemisphere, and the tumor was subtotally removed by right suboccipital craniotomy. Histologic examination showed that the tumor cells contained eosinophilic cytoplasm and spindle-shaped processes with Rosenthal fibers and eosinophilic granular bodies, diagnosed as a typical pilocytic astrocytoma (PA). The MIB-1 index was <1%. The patient did not receive postoperative adjuvant radiation and chemotherapy. Two months after surgery, magnetic resonance imaging showed growth of the residual tumor adjacent to the fourth ventricle, causing obstructive hydrocephalus. She underwent surgery again, and the tumor was totally removed. Histologic findings showed mitotic cells and increased cellularity compared with the primary tumor, which was compatible with anaplastic transformation of PA with a MIB-1 index of 50%. Postoperatively, she was observed with best supportive care without postoperative adjuvant therapy. Nine months after the second operation, she died due to tonsillar herniation and obstructive hydrocephalus caused by a recurrent tumor. An autopsy was performed. CONCLUSIONS: It is extremely rare, as in the present case, that a cerebellar PA in an elderly patient recurs rapidly with anaplastic transformation, despite deferred postoperative adjuvant therapy including radiation and chemotherapy. A novel molecular-targeted therapy is needed for anaplastic PA showing aggressive biological behavior.

Refractory De Novo Multiple Cerebral Aneurysms After Radiotherapy and Multistaged "Open" Surgical Treatment for Low-Grade Glioma During Long-Term Follow-Up: A Case Report and Review of the Literature.

BACKGROUND: Radiation-induced aneurysms have been previously reported; however, multiple and repeated de novo aneurysm formation chronologically and anatomically during long-term follow-up have not yet been observed. The pathogenesis of persistent radiation-induced vasculopathy is not fully understood. CASE DESCRIPTION: A 31-year-old woman presented with intraventricular hemorrhage due to rupture of a right internal carotid artery (ICA) aneurysm that developed 17 years after surgical resection of a low-grade glioma in the right frontal lobe and postoperative radiotherapy (focal, 50 Gy/25 fractions). During glioma follow-up, salvage surgery with adjuvant gamma knife therapy and chemotherapy (ranimustine, vincristine, temozolomide) were performed for recurrence of the glioma. The aneurysm was treated with endovascular coil embolization. However, she experienced repeated intraventricular hemorrhages, and angiography revealed a de novo ICA aneurysm. The de novo aneurysms were treated with endovascular surgery using coil embolization and stenting. At 2 years after the third hemorrhage, the surgical wound became dehiscent, probably due to wound infection, thus epicranial soft tissue reconstruction using vascularized skin flap was performed. Despite multistaged endovascular surgery for the ICA aneurysm, she experienced repeated subarachnoid and intraventricular hemorrhages. Angiography revealed a de novo aneurysm of the right posterior cerebral artery and basilar trunk. She underwent coil embolization and stenting. Despite active management with endovascular surgery and close follow-up, she died after an eighth consecutive intraventricular and intracerebral hemorrhage caused by a de novo large aneurysm of the posterior cerebral artery. CONCLUSIONS: To the best of our knowledge, the present study is the first to report on of refractory and recurring de novo aneurysms treated by multistaged endovascular surgery during a long-term follow-up after radiotherapy and multistaged craniotomy for glioma.

Spinal Extradural Arteriovenous Fistula with Cowden Syndrome: A Case Report and Literature Review Regarding Pathogenesis and Therapeutic Strategy.

We report the case of a patient with a spinal extradural arteriovenous fistula (AVF) associated with Cowden syndrome (CS) that was successfully treated by endovascular surgery. CS is an autosomal dominant disorder associated with diverse symptoms caused by a deleterious mutation in the phosphatase and tensin homolog (PTEN) gene. A 67-year-old woman was diagnosed with CS based on her medical history of multiple cancers for which she underwent abdominal surgery, macrocephaly, Lhermitte-Duclos disease, and facial papules. Her genetic testing demonstrated a PTEN mutation. She presented with progressive paraparesis and her MRI of the thoracolumbar spine showed the spinal cord edema along with flow voids. A spinal angiogram demonstrated a spinal extradural AVF with the perimedullary drainage. The AVF was successfully treated by endovascular surgery. The PTEN mutation can accelerate angiogenesis; thus, vascular anomalies are one of the diagnostic criteria of CS. However, only two cases of vascular anomalies involving the spinal cord in patients with CS have been reported previously. As the present case, both cases had a history of abdominal or retroperitoneal cancer. The PTEN mutation accompanied with abdominal surgery might have caused this vascular anomaly as the consequences of venous congestion around the thoracolumbar spine. A spinal extradural AVF should be considered in patients with CS who present with myelopathy, especially when the patient has a history of abdominal or retroperitoneal surgery. Regarding the treatment strategy, endovascular surgery should be considered because surgical insult could prompt secondary vascular anomalies resulting from neovascularization due to the PTEN mutation.

Concomitant Intracranial and Lumbar Chronic Subdural Hematoma Treated by Fluoroscopic Guided Lumbar Puncture: A Case Report and Literature Review.

A 40-year-old man presented with a severe headache, lower back pain, and lower abdominal pain 1 month after a head injury caused by falling. Computed tomography (CT) of the head demonstrated bilateral chronic subdural hematoma (CSDH) with a significant amount in the left frontoparietal region. At the same time, magnetic resonance imaging (MRI) of the lumbar spine also revealed CSDH from L2 to S1 level. A simple drainage for the intracranial CSDH on the left side was performed. Postoperatively, the headache was improved; however, the lower back and abdominal pain persisted. Aspiration of the liquefied spinal subdural hematoma was performed by a lumbar puncture under fluoroscopic guidance. The clinical symptoms were dramatically improved postoperatively. Concomitant intracranial and spinal CSDH is considerably rare so only 23 cases including the present case have been reported in the literature so far. The etiology and therapeutic strategy were discussed with a review of the literature. Therapeutic strategy is not established for these two concomitant lesions. Conservative follow-up was chosen for 14 cases, resulting in a favorable clinical outcome. Although surgical evacuation of lumbosacral CSDH was performed in seven cases, an alteration of cerebrospinal fluid (CSF) pressure following spinal surgery should be reminded because of the intracranial lesion. Since CSDH is well liquefied in both intracranial and spinal lesion, a less invasive approach is recommended not only for an intracranial lesion but also for spinal lesion. Fluoroscopic-guided lumbar puncture for lumbosacral CSDH following burr hole surgery for intracranial CSDH could be a recommended strategy.

Chronic Encapsulated Expanding Thalamic Hematoma Associated with Obstructive Hydrocephalus following Radiosurgery for a Cerebral Arteriovenous Malformation: A Case Report and Literature Review.

Chronic encapsulated intracerebral hematoma is a unique type of intracerebral hematoma accompanied by a capsule that is abundant in fragile microvasculature occasionally causing delayed regrowth. A 37-year-old man who had undergone radiosurgery for an arteriovenous malformation (AVM) causing intracerebral hematoma in the left parietal lobe presented with headache, vomiting, and progressive truncal ataxia due to a cystic lesion that had been noted in the left thalamus, leading to progressive obstructive hydrocephalus. He underwent left frontal craniotomy via a transsylvian fissure approach, and the serous hematoma was aspirated. The hematoma capsule was easy to drain and was partially removed. Pathological findings demonstrated angiomatous fibroblastic granulation tissue with extensive macrophage invasion. The concentration of vascular endothelial growth factor (VEGF) was high in the hematoma (12012 pg/mL). The etiology and pathogenesis of encapsulated hematoma are unclear, but the gross appearance and pathological findings are similar to those of chronic subdural hematoma. Based on the high concentration of VEGF in the hematoma, expansion of the encapsulated hematoma might have been caused by the promotion of vascular permeability of newly formed microvasculature in the capsule.

Thoracic discectomy by posterior pedicle-sparing, transfacet approach with real-time intraoperative ultrasonography: Clinical article.

OBJECT: Symptomatic thoracic disc herniations (TDHs) are relatively uncommon, and the technical challenges of resecting the offending disc are formidable due to the location of spinal cord that has relatively poor perfusion characteristics within a narrow canal. The majority of disc herniations are long-standing calcified discs that can be adherent to the ventral dura. Real-time intraoperative ultrasound (RIOUS) visualization of the spinal cord during the retraction and resection of the disc greatly enhances the safety and efficacy of disc resection. The authors have adopted the posterior laminectomy with pedicle-sparing transfacet approach with real-time ultrasound guidance in their practice, and they present the clinical outcome in their patients to illustrate the safety profile of this technique. METHODS: Sixteen consecutive patients undergoing operative management of TDHs were identified from the authors' database. All patients underwent microdiscectomy through a posterior transfacet pedicle-sparing approach under RIOUS. Outcomes and complications were retrospectively assessed in this patient series. Clinical records and pre- and postoperative imaging studies were scrutinized to assess levels and types of disc herniation, blood loss, surgical time, pre- and postoperative Nurick grades, Japanese Orthopaedic Association (JOA) scores, and complications. RESULTS: All patients had single-level symptomatic TDHs. The patients presented with symptoms including thoracic myelopathy, axial back pain, urinary symptoms, and thoracic radiculopathy. Thoracic disc herniations involved levels T2-3 to T12-L1. Discs were classified as central or paracentral, and as calcified or noncalcified. All discs were successfully removed with no incidence of neural injury or CSF leak. The mean estimated blood loss was 523 ml, and the mean surgical time was 159 minutes. Nurick grades improved on average from 3.3 to 1.6. The mean JOA scores improved from 5.7 to 8.3 out of 11. The mean Hirabayashi recovery rate of the JOA score was 57%. All patients reported improvement in symptoms compared with preoperative status except for 1 patient with an American Spinal Injury Association Grade A spinal cord injury prior to surgery. The average duration of follow-up was 10.5 months. One patient developed postoperative wound infection that required additional operative debridement and revision of hardware. CONCLUSIONS: Thoracic discectomy via a posterior pedicle-sparing transfacet approach is an adequate method of managing herniations at any thoracic level. The safety of the operation is significantly enhanced by the use of realtime intraoperative ultrasonography.

Slow progression of calcified cerebellar metastasis from ovarian cancer: a case report and review of the literature.

The report describes a rare case of a patient with a calcified cerebellar metastasis arising from a primary ovarian cancer. The patient was a 33-year-old woman with a long history of stage IIIc ovarian cancer who had undergone transabdominal hysterectomy and bilateral oophorectomy followed by chemotherapy with gemcitabine hydrochloride. Incidentally, computed tomography (CT) revealed a cerebellar tumor with calcification. The size of the tumor gradually increased, and lateral suboccipital craniotomy was performed for gross total removal of the tumor. The histological diagnosis was ovarian mucinous adenocarcinoma. The patient's postoperative course was uneventful, and she was discharged two days after surgery. Brain metastases from ovarian cancer are rare. In the review of metastatic brain tumors arising from a primary ovarian cancer in the Department of Obstetrics and Gynecology at our institution, this phenomenon was noted in only 10 cases (0.24%) of 4,158 patients with ovarian cancer seen at our center over a period of 8 years. Moreover, only three cases of calcified metastatic brain tumor have been reported previously. In conclusion, complete tumor resection may be an acceptable approach for patients with calcified metastatic tumors both for therapeutic considerations and to obtain tissue for confirmation of histopathological diagnosis. Metastatic brain tumors can be calcified, and should be considered within the differential diagnosis of calcified intracranial lesions to avoid any delay in diagnosis or treatment.

Prevalence of spinal meningeal cyst in the sacrum.

Spinal meningeal cysts in the sacrum (SMC) are known to be occasionally symptomatic with low back pain as well as leg pain, but no distinct prevalence of this pathological entity including asymptomatic lesions has been described. This prospective study investigated the prevalence of SMCs based on magnetic resonance (MR) myelography in 102 consecutive Japanese women with gynecological problems, who underwent pelvic conventional MR imaging. Ten of 102 patients were suspected of being positive for SMC (9.8%), but pseudo-positive findings were possible. A high probability of positive SMC was found in 7/102 (6.9%). MR myelography was better to detect SMCs than conventional MR imaging. Multiplicity and female preponderance may be other features of SMC. The speculated prevalence of SMCs in Japanese females ranged from 6.9% to 9.8%.

Combined unilateral hemilaminectomy and thoracoscopic resection of the dumbbell-shaped thoracic neurinoma: a case report.

A 41-year-old woman complained of chest pain when coughing. Computed tomography and magnetic resonance imaging disclosed a homogenously enhanced tumor occupying the spinal canal at the Th7 level and extending into the right paravertebral space through the intervertebral foramen between Th7 and Th8. The tumor was successfully removed via a posterolateral approach using unilateral hemilaminectomy followed by thoracoscopic surgery. Since the tumor had a dumbbell shape, a combined approach was considered essential. The histological diagnosis was a thoracic neurinoma. Combined hemilaminectomy and thoracoscopic surgery may be a good alternative for the management of thoracic dumbbell-shaped tumors.

A unique device, the disc space-fitted distraction device, for anterior cervical discectomy and fusion: early clinical and radiological evaluation.

OBJECT: To perform interbody distraction and to obtain spinal curvature correction during anterior cervical discectomy and fusion (ACDF), the authors recently adopted a new stand-alone device, a disc space-fitted distraction device (DFDD). In this preliminary report the authors introduce this unique device and discuss some advantages in terms of short-term clinical and radiological evaluations. METHODS: The most unique aspect of the DFDD is the function of gentle distraction at anterior disc space with maximum lordotic correction of up to 8 degrees while rotating a screw at the front of the device. Additional advantages are related to its configuration such as disc space-matched shape in all dimensions, tapering contour for easy insertion into the disc space, multiple spikes to avoid dislodgment, wider contact area to the vertebral endplate for diminishing sinking process, and sufficient space for accommodation of bone-conductive materials. Twenty-four patients who have been observed more than 12 months after ACDF were involved in this evaluation. RESULTS: The objective clinical outcome, measured by the Neurological Cervical Spine Scale, was significantly improved. In radiological evaluation, statistically significant improvement compared with preoperative values was noted on the curvature index, C2-7 curvature, and disc angle (p < 0.01) throughout the entire postoperative period, up to 12 months. A high fusion rate and remodeling process around the implants were also observed. CONCLUSIONS: The DFDD may have some advantages over other devices-its distraction action, diminished sinking, and early solid bone union resulted in maintaining sufficient correction of the spinal curvature. This corrected spinal curvature may play an important role in preventing progressive adjacent-disc degeneration subsequent to ACDF in the long term.

New surgical technique to secure the bone strut during anterior cervical corpectomy and fusion: kusabi fixation technique--technical note.

Fixation using an anterior cervical plate is frequently used in anterior cervical discectomy or corpectomy and fusion procedures because of the higher fusion rate than without instrumentation. The surgical outcomes with the anterior plate technique are acceptable, but various hardware-related complications have been reported. The authors describe a new surgical technique, called the kusabi fixation technique, for securing the bone strut during anterior cervical corpectomy using cylindrical cages. Following corpectomy, the trimmed bone strut was placed into the space drilled-out. Two small holes of 5-6-mm diameter and 5-mm depth were drilled out at the interface of two bones at the top and bottom of the bone strut in a diagonal orientation. Two cylindrical cages filled with autologous bone tips were tapped into the interface. Eight patients with myelopathy were treated by this method. All procedures were uneventfully performed as a single level surgery (two vertebral bodies and one disk level). Solid bone union was obtained in all patients at 6 months after the operation. Apparent alignment change in the cervical spine was observed in only one patient, who developed asymptomatic kyphosis. No instrumentation failure or significant complications related to the surgery occurred. Precise biomechanical aspects and long-term radiographic analysis compared with the plate fixation technique should be established, but this new method provides another way to secure the bone strut in anterior cervical corpectomy and fusion.