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OBJECTIVE A recent comparative analysis between neurosurgical and endovascular treatments for craniocervical junction (CCJ) arteriovenous fistulas (AVFs) revealed better treatment outcomes in the neurosurgery group than in the endovascular group. This finding was attributed to the higher than expected rate of ischemic complications in the endovascular group than in the neurosurgery group (26% vs 7.7%, p = 0.037). The aim of the present study was to describe ischemic complications associated with treatments for CCJ AVFs. METHODS This descriptive study was authorized by the Neurospinal Society of Japan. Data from 97 consecutive patients with CCJ AVFs who underwent neurosurgical (n = 78) or endovascular (n = 19) treatment between 2009 and 2019 were collected from 29 centers. The primary endpoints were details on ischemic complications and their risk factors. Secondary endpoints were details on other complications. RESULTS Among all major complications, ischemic complications were the most common (11% of 97 patients), followed by hemorrhagic complications (7.2%), hydrocephalus (2.1%), and CSF leakage (2.1%). Ischemic complications included 8 spinal, 2 brainstem, and 1 cerebellar infarctions. Iatrogenic occlusion of the anterior or posterior spinal artery from the radiculomedullary or radiculopial arteries caused these complications. Ischemic complications resulted in neurological deficits, including motor paresis, sensory disturbances, and brainstem dysfunction. The modified Rankin Scale score was 3 or higher in 36% of patients with ischemic complications at the final follow-up of 23 months. Risk factors associated with ischemic complications were endovascular treatment (OR 4.3, 95% CI 1.1–16) and spinal feeding arteries (OR 3.8, 95% CI 1.03–14). Most of the other complications were addressed by additional treatment without permanent neurological deficits. CONCLUSIONS Among ischemic complications associated with treatments for CCJ AVFs, spinal infarctions were the most common and were mostly attributed to endovascular procedures for CCJ AVFs fed by spinal arteries. These results support the use of neurosurgery as the first-line treatment for CCJ AVFs.

Background Motor evoked potential (MEP) recording is used as a method to monitor integrity of the motor system during surgery for intramedullary tumors (IMTs). Reliable sensitivity of the monitoring in predicting functional deterioration has been reported. However, we observed false positives and false negatives in our experience of 250 surgeries of IMTs. Objective To delineate specificity and sensitivity of MEP monitoring and to elucidate its limitations and usefulness. Methods From 2008 to 2011, 58 patients underwent 62 surgeries for IMTs. MEP monitoring was performed in 59 operations using transcranial electrical stimulation. Correlation with changes in muscle strength and locomotion was analyzed. A group undergoing clipping for unruptured aneurysms was compared for elicitation of MEP. Results Of 212 muscles monitored in the 59 operations, MEP was recorded in 150 (71%). Positive MEP warnings, defined as amplitude decrease below 20% of the initial level, occurred in 37 muscles, but 22 of these (59%) did not have postoperative weakness (false positive). Positive predictive value was limited to 0.41. Of 113 muscles with no MEP warnings, 8 muscles developed postoperative weakness (false negative, 7%). Negative predictive value was 0.93. MEP responses were not elicited in 58 muscles (27%). By contrast, during clipping for unruptured aneurysms, MEP was recorded in 216 of 222 muscles (96%). Conclusion MEP monitoring has a limitation in predicting postoperative weakness in surgery for IMTs. False-positive and false-negative indices were abundant, with sensitivity and specificity of 0.65 and 0.83 in predicting postoperative weakness.

Neurocutaneous melanosis (NCM) is a rare condition characterized by central nervous system melanocytic tumors associated with congenital melanocytic nevi. Phacomatosis pigmentovascularis (PPV) is an association of vascular nevus with pigmentary nevus. Aberrant maturation of neural crest-derived cells is considered to be related to pathogenesis in both conditions. However, association of NCM and PPV has not been reported to the best of our knowledge. Melanocytoma, which usually involves the leptomeninges or spinal cord, is extremely rare in the retroperitoneum. We present here a case of a patient with NCM, PPV, and melanocytic tumors in the spinal cord and retroperitoneum, which were treated surgically. A 40-year-old woman had a 2-year history of dysesthesia and weakness in the left leg. History included congenital giant blue nevus-like lesion in the trunk, a port-wine stain in the sacral area, and Caesarean section performed 8 years before, when diffuse pigmentation in the peritoneum was noted. Magnetic resonance (MR) imaging of the spine revealed an intramedullary tumor at T10 level with paramagnetic signal characteristics. The spinal cord tumor was totally removed, and the histological diagnosis was melanocytoma. Three months later, a left retroperitoneal mass with histological features of melanocytic tumor was removed. Neither tumors recurred and the patient stays ambulatory 4 years after the surgery. Multiple subtypes of melanocytic tumors with distinctive features of NCM and PPV can develop simultaneously, mimicking malignant melanoma. Gross total resection of each tumor, when indicated, is beneficial.

Cervical laminoplasty was developed as an alternative to cervical laminectomy for treatment of cervical myelopathy, in which hinges are created to lift the lamina. Various techniques of laminoplasty have since been developed after two prototype techniques: Hirabayashi's open-door laminoplasty and Kurokawa's spinous process splitting (double-door) laminoplasty. Several in vitro studies report superior biomechanical stability of the cervical spine after laminoplasty compared with laminectomy. In clinical situation, randomized control studies are scarce and superiority of one procedure over another is not uniformly shown. Lack of hard evidence supporting the purported advantages of laminoplasty over laminectomy, that is, reduced rate of postoperative instability and kyphosis development, while preserving range of motion (ROM), has been a weak selling point. Currently, laminoplasty is performed by majority of spine surgeons in Japan, but is rarely performed in the United States and Europe. Recent development in laminoplasty is preservation of muscle attachment, which enabled dynamic stabilization of the cervical spine by neck extensor muscles. After treatment with new laminoplasty techniques with active postoperative neck ROM exercises, postoperative instability, kyphosis, axial neck pain, and loss of ROM seems minimal. Well-designed clinical trials to show the effectiveness and long-term outcome of this surgical procedure are warranted.

Background Temporal bone chondroblastoma is a rare primary bone tumor that affects the floor of the middle cranial fossa. This tumor is known to have high recurrence rate after curettage, and wide resection is therefore recommended. However, the literature provides little information regarding long-term results after wide resection of temporal bone chondroblastoma. Methods Four cases of surgically treated temporal bone chondroblastoma underwent long-term follow-up. Results Four patients, 3 males and 1 female, with mean age of 34, were surgically treated at the neurosurgery department of Keio University Hospital. Two patients were treated for recurrent tumor and the other two for new disease. In all cases the tumor mainly involved the mandibular fossa with variable degree of infiltration into tympanic and petrous parts. The tumor was totally removed via zygomatic approach in all patients. In 3 patients, the mandibular condyle was removed to expose the tumor. These patients had temporary malocclusion and restricted motion postoperatively, which resolved within 3 to 12 months with conservative treatment. All patients have no recurrence to date with a mean follow-up period of 9 years. Conclusion Temporal bone chondroblastoma was removed totally with skull base surgical technique and no recurrence has occurred for 6 to 13 years postoperatively. We found that removal of the mandibular head does not cause permanent problems of mastication in patients with normal dentures.

OBJECTIVE AND IMPORTANCE Spinal accessory schwannomas unassociated with neurofibromatosis are very rare, and only 30 cases have been reported in the literature. To our knowledge, this is the first report of a spinal accessory schwannoma mimicking a tumor of the fourth ventricle. CLINICAL PRESENTATION A 50-year-old man presented with neck pain after being involved in a motor vehicle accident. There were no neurological deficits, but a computed tomographic scan revealed a large hypodense mass with punctuate calcifications in the fourth ventricle. The tumor exhibited low intensity on the T1-weighted magnetic resonance imaging scan and high intensity on the T2-weighted scan, and it showed inhomogeneous contrast enhancement. INTERVENTION The tumor was totally removed by a bilateral suboccipital craniectomy and C1 laminectomy. Dissection of the surgical specimen revealed that the tumor had originated from the left spinal accessory nerve. Histopathological examination confirmed the diagnosis of schwannoma. The patient experienced transient postoperative cerebellar ataxia but recovered completely. CONCLUSION Intracisternal-type spinal accessory schwannomas sometimes mimic a tumor of the fourth ventricle. Total surgical resection can be achieved with good outcome.

Scedosporium apiospermum, the asexual anamorph of Pseudallescheria boydii, is a ubiquitous saprophytic fungus that usually causes cutaneous/subcutaneous infection but may manifest as an invasive disease, often in immunocompromised hosts. Following an extensive literature review, we think that this case represents the first documented report of a primary infection of the spine in an immunocompetent patient. Despite extensive surgical debridement and itraconazole therapy, the patient died of multisystem organ failure of unknown etiology. Our case and three previously reported cases of P. boydii vertebral osteomyelitis highlight the importance of obtaining repeat cultures in patients with culture-negative vertebral osteomyelitis who fail to adequately respond to empiric standard antibacterial and/or antimycobacterial therapy. Combined surgical debridement and antifungal therapy have been required for eradication of P. boydii spinal infections in two previously reported immunocompromised patients, although the optimal antifungal regimen for this infection has not been established.

Two patients with giant intracavernous internal carotid artery (ICA) aneurysms were intolerant to balloon test occlusion of the ICA, and later developed spontaneous thrombosis of the aneurysm and the parent ICA without ischemic sequelae. Case 1: A 60-year-old female with a giant right intracavernous ICA aneurysm presented with right abducens nerve paresis. An unsuccessful extracranial-to-intracranial bypass graft operation was complicated by transient postoperative ophthalmoplegia. The patient did not tolerate balloon test occlusion of the right ICA after attempted bypass surgery, and was treated conservatively. The patient presented with acute onset of headache 3 years later. Case 2: A 50-year-old female with a giant right intracavernous ICA aneurysm presented with right abducens nerve paresis. The patient was managed conservatively after a positive balloon test occlusion of the right ICA. The patient suffered transient hypopituitarism and acute onset of headache 2 years later. Spontaneous thrombosis of the aneurysms and occlusion of the parent ICA were found in both patients. Neither had major hemispheric infarcts, but the first patient had asymptomatic infarcts, which were presumed to be thromboembolic in nature. Patients with intracavernous ICA aneurysms who have positive balloon test occlusions appear to develop tolerance to spontaneous and gradual occlusion of the ICA without significant sequelae. However, these patients have an increased risk of developing embolic infarctions. The role for anticoagulation and repeat hemodynamic tests remains unclear.

Drill-induced heat has been suspected as a cause of tissue injury, and there are ample experimental data to substantiate the implication. However, no clinical results have been presented with measurement of temperature in the vicinity of neural structures during the actual spinal procedures. Using a thermocouple, temperature in the gutters drilled in the midline and the lateral margins of the lamina was monitored closely in 61 patients, who underwent the French-door style of cervical spino-laminoplasty. The drilling was performed intermittently for a duration of 5 or 10 seconds, using 3- or 5-mm diamond burrs with sufficient continuous cooling irrigation. The correlations between bone temperature elevation and postoperative sensorimotor symptoms were then analyzed. In the lateral gutters at the most cephalad level (typically C3), where the drilling was performed underneath an overlying bundle of muscle attached to C2's spinous process, the temperature rose significantly. This occurred even with 5-second drilling sessions. The average peak temperature was 44 °C at this level. At all other sites, the temperature was maintained below 40 °C. In three patients, transient neurological deficit developed postoperatively, which did not correlate with the incidence of bone temperature elevation. Intermittent drilling with sufficient irrigation can prevent thermal neuronal damage generated by high-speed drills. Drilling with small diamond burrs in deep and narrow spaces covered by overlying muscles predisposes to inadequate irrigation and thermal elevation. Continuous, protracted drilling without frequent irrigation may result in excessive heat generation and nerve injury.

Fluorescence angiography with indocyanine green (ICG) provides real-time information regarding the patency of vessels. To enhance the capability to delineate flow direction, flow velocity and sequence of dye filling in different components of complex spinal vascular lesions such as perimedullary arteriovenous fistulas (AVFs), we tried selective intraarterial injection of ICG with catheterization in the proximity of the AVFs.Prior to taking the position for surgery, a metallic introducer sheath was placed into the femoral artery, and placed over the patient's lateral buttock. After the exposure of the AVFs, a standard angiographic catheter was advanced into the proximal portion of the feeding artery and a small volume of diluted ICG (0.06 mg in 5 ml saline for one examination) injected repeatedly. To avoid the thromboembolism, heparinized saline was perfused continuously thorough the catheter and sheath.The small injection volume and the close proximity of the injection site to the lesions resulted in quick rise and fall of the fluorescence without any background. Time and spatial resolution of analysis were enhanced; flow dynamics such as direction, velocity and alteration after temporary occlusion were well visualized. The feeders and drainers were clearly distinguished, and the shunts could be precisely identified.Selective intraarterial injection ICG fluorescence angiography was very useful for perimedullary AVFs. Albeit that it requires intraoperative selective catheterization, this repeatable technique has an advantage to improve temporary resolution and provides accurate information of the flow dynamics through the complex anatomy of vascular lesions.

Spine surgery has made radical advancements in the last two decades and provision has expanded a great deal. The history of the technical development is briefly reviewed. To analyze trends in utilization and to assess the macroeconomic demand for spine surgery, the incidence of all spine surgery per capita is estimated referring to diverse statistical data from the USA, Korea and Japan. When compared internationally, there is a great disparity in the utilization of spine surgery, especially for fusion/instrumentation. Medico-socioeconomic conditions underlying the variations are discussed. Adequate surgeon training has to be supplied in a matched volume, and the number of surgeons to balance the need is estimated.

Object Laminoplasty has been used to expand the cervical spinal canal, based on the belief that reconstruction of the laminae preserves musculoskeletal function. The true efficacy of laminoplasty for maintaining spinal alignment, stability, and flexibility, however, remains to be proven. The authors have developed a new method, myoarchitectonic spinolaminoplasty (MSLP), which preserves all of the nuchal muscles and reconstitutes all of the musculoskeletal couplings to the posterior elements of the vertebrae. The details of this technique are described, and the efficacy of the technique in conserving muscle volume, alignment, and motion, as well as in preventing postoperative musculoskeletal discomfort, is assessed. Methods The authors' previous midline-splitting laminoplasty procedure, which utilized a hydroxyapatite (HA) implant as a substitute for the spinous process, was improved. Detachment of the muscles is avoided with this new technique by cutting inside the spinous process. The bone–muscle flaps are affixed to the HA spinous process. Radiographs, computed tomography scans, and neurological evaluations obtained at the 1-year follow-up in the groups of consecutive patients assessed immediately prior to and after the modification of the previous technique (the control and the MSLP groups, respectively) were analyzed and compared. Results The HA bone constructs became integrated due to osteoconduction. The cross-sectional area of the semispinalis capitis, semispinalis cervicis, and multifidus muscles remained significantly larger in the MSLP group. Slight attenuation in lordosis was observed in the control group, but was prevented in the MSLP group. Range of motion was somewhat restricted in the MSLP group, but the incidence of neck pain and shoulder strain was significantly reduced. Conclusions The new MSLP method was effective in preserving the volume and functions of the nuchal musculature and helping to minimize postoperative musculoskeletal complaints.

A 40-year-old woman presented with a right petroclival meningioma compressing the brainstem and manifesting as a 6-month history of headache and gait difficulty. The patient underwent subtotal removal of the tumor via an anterior transpetrosal approach. The postoperative course was complicated by cerebrospinal fluid rhinorrhea, bacterial meningitis, and acute hemorrhagic rectal ulcer. The patient was discharged home in good condition after prolonged medical treatment. Four months after the surgery, the patient noted recurrence of gait difficulty. Magnetic resonance (MR) imaging of the brain showed enlargement of the ventricles and no residual brainstem compression. A ventriculoperitoneal shunt was placed, but the symptoms were unchanged. The shunt was removed 2 months later because of infection. The patient's gait gradually deteriorated, although repeat brain MR imaging showed no significant increase in ventricular size. Ten months after the initial surgery she became paraplegic. MR imaging of the thoracic spine revealed a large arachnoid cyst extending from C-6 to T-6. The patient underwent T2-4 laminectomy, partial removal of the cyst wall, and duraplasty, but no clinical improvement was observed. Preexisting long-tract signs and coincidental hydrocephalus confused the neurological findings and delayed detection of the spinal lesion in this case. Neurosurgeons should be alert to the possibilities of insidious spinal lesion if the patient has progressive neurological disorder which does not match the known cranial lesion.

A 27-year-old female presented with gait disturbance and left facial paresthesia. She had a history of breast and lung masses not yet identified. Magnetic resonance (MR) imaging revealed a tumor suggesting a petroclival meningioma. Her symptoms worsened rapidly. MR imaging showed enlargement of the tumor. Subtotal removal of the tumor was performed. Histological examination revealed metastatic adenocarcinoma. Examination of the other masses confirmed adenocarcinoma originating from lung carcinoma. Dural metastases can be difficult to preoperatively differentiate from meningioma clinically or radiographically. MR spectroscopy and laboratory examinations such as cytologic and serologic studies are valuable for differential diagnosis. The final diagnosis of the tumor depends on the histological findings. However, careful monitoring of the patient's course is very important to detect rapid growth of metastases.

Background In this prospective 18-month study, 29 patients underwent posterior thoracic instrumentation with placement of 209 transpedicular screws guided by intraoperative fluoroscopic imaging and anatomic landmarks. We assessed the safety, accuracy, complications, and early stability of this technique. Methods Pedicle and pedicle-rib units were measured, and screw cortical penetrations were graded on anatomy and depth of penetration. All 29 patients underwent preoperative computed tomographic (CT) imaging, and 28 underwent postoperative CT imaging (199/209 screws). Results From T2 to T12, screw diameters were >or=5 mm with mean medial screw angulation measuring 20-25 degree. Of the 209 screws placed from T1 to T12, 111 had diameters greater than or equal to the pedicle width. From T3 to T9, the mean diameter of the pedicle screws exceeded the mean pedicle width. Lateral pedicle wall penetration occurred significantly more often than superior, inferior, and medial pedicle wall penetrations and anterolateral vertebral body penetration. Five of six high-risk screw penetrations occurred in one patient when intraoperative technique was compromised. We observed no new postoperative neurologic deficits, visceral injuries, or pedicle screw instrumentation failures. The three high-risk anterolateral vertebral body penetrations at T1 and T2 were associated with a significantly decreased mean screw transverse angle; the three high-risk medial pedicle wall penetrations occurring from T3 to T9 were associated with a significantly increased mean screw transverse angle. Among all 26 patients available at postoperative follow-up (mean 11.9 months), the mean loss of kyphosis correction was 2.0 degree. Conclusions Guided by intraoperative fluoroscopic imaging and anatomic landmarks, thoracic pedicle screws can be placed safely. Early clinical follow-up reveals excellent results with minimal loss of kyphosis correction.

An 81-year-old female presented with severe headache. Computed tomography revealed subarachnoid hemorrhage. She developed right facial nerve paresis on the next day. Angiography revealed a right vertebral artery-posterior inferior cerebellar artery aneurysm. The aneurysm was successfully occluded with interlocking detachable coils (IDCs) on the 7th day. Magnetic resonance (MR) imaging 1 month after IDC placement showed partially thrombosed aneurysm near the internal acoustic meatus. Ten months after the ictus, MR imaging revealed marked resolution of the intra-aneurysmal thrombus and reduction of the aneurysm size. Her facial nerve function gradually recovered during this period. Her facial nerve paresis was probably caused by acute stretching of the facial nerve by the ruptured aneurysm that was in direct contact with the nerve. Intra-aneurysmal thrombosis using coils can reduce aneurysm size and alleviate cranial nerve symptoms.