The purpose of this study was to evaluate the clinical accuracy and safety of PPS using C-arm fluoroscopy and the efficacy of the PPS augmented with calcium phosphate cement(CPC)in the osteoporotic spine. 246 patients underwent MIS-TLIF/PLIF using PPS,and 90 patients with osteoporotic spines were augmented with calcium phosphate cement. Postoperative CT scans were used to detect screw positions and categorized according to Youkilis classification for assessment of bony union. Follow up CT at 6 months were obtained. A total of 1054 PPSs were placed. 1004 were classified as good, 42 were acceptable,and 8 were unacceptable. 4 patients with medial breach underwent revision for unbearable radicular pain. Bony union rate was 97.8% within 6 months after the operation in all cases augmented with CPC. PPS insertion was performed safely during MISTLIF/ PLIF. However,the starting point for the pedicle screw insertion and the shape of the TPfacet junction were considered to be risk factors for accurate PPS placement. CPC increased PPS stability for patients with osteoporotic spines.

Purpose：We present the evaluation of PMMA in the vertebral body after performing vertebroplasty with posterior instrumentation for vertebral collapse of osteoporotic compression fractures.

Materials & Methods：25 patients underwent this vertebroplasty between July 2004 and May 2011. We investigated the kyphotic angle, anterior column % loss in the vertebral body, X-ray findings of PMMA and the condition around the PMMA.

Results：Radiologically, the kyphotic angle and the average anterior column % loss were sequentially diminished. A clear zone around PMMA was seen in two cases, but there were no broken PMMA or screw loosenings in vertebral bodies with PMMA.

Discussion and Conclusion：We suggest that PMMA is useful for the stability of the vertebral body and the augmentation of the screw.

Background：Recently, posterior fixation techniques using pedicle screws or lateral mass screws have been reported with excellent fusion rates in cervical and lumbar spine surgery. Nevertheless, such spinal instrumentations require screw anchoring, which may expose the vertebral artery or neural structures.

Case description：In the present retrospective review, we report our experiences applying the spinous process plate system to a primary and salvage fixation device for trauma and tumor of cervical and lumbar spines. We performed primary in situ fusion surgeries for traumatic cervical dislocation in 2 cases, salvage fusion for metastatic cervical tumor in 1 case, primary fusions after facetectomies in 2 cases(1 for lumbar tumor and 1 for lumbar radiculopathy). Although complete bony fusion was achieved postoperatively in cervical trauma cases, complete bony fusion was not detected in the 2 patients who underwent lumbar surgery. Post operative infection developed in the patient with cervical metastatic tumor.

Conclusions：We suggest that this posterior fixation technique is safe and easy to perform. Furthermore, this technique can be applied to a primary cervical fusion. Further studies with larger patient numbers are needed.

I have inserted PLIF cages like TLIF cages in the lumbar interbody fusion since 2009. The maneuver is described below.
First of all, decompression of the spinal canal stenosis is performed from the impaired side using endoscopic or mini-open surgery. Local bone should be stocked as much as possible, and is used to fill the anterior half of the intervertebral space. Before inserting the intervertebral cages, it is necessary to shave and make a space using a shaver 1 or 2 sizes smaller. Under fluoroscopic image, the intervertebral cage should be inserted obliquely until its anterior top comes to an adequate position in the intervertebral space. The grasper is then removed. The bone impacter is set on the hole of the cage, and impacted. The cage is rotated until lying horizontally. A second cage which is longer than the first one could be inserted if necessary.

I have experienced 4 cases of complications among 120 cases. Two cases were the backing out of the cages into the spinal canal. In two further cases, there was destruction of the cage caused by excessive impaction when they were inserted.

Purpose：We report the outcomes of 6 cases with atlantoaxial subluxation(AAS)using laminarscrew(LS)to fix either side of C2.

Materials & Methods：6 patients showing high riding of the vertebral artery on either side were treated with the procedure. Their age ranged from 61 to 82 years-old. The etiology of AAS was rheumatoid arthritis in 3 cases, instability after laminoplasty in 2 and Os odontoideum in 1. All cases showed high riding of the vertebral artery on either side. Follow-up ranged from 4 months to 12 months. We used bilateral lateral mass screws(LMS)in the atlas(C1)and pedicle screws(PS)and LS in C2 with en-block iliac bone graft. Surgical results were evaluated with JOA score, atlantodental interval(ADI), bone union and location of each screw.

Results：All cases achieved bone union without any complications. Mean JOA score improved from 9.5 preoperatively to 13.5 points postoperatively. Mean ADI improved from 9.8mm to 3.2mm. Only one LS was inserted into the vertebral canal without any clinical symptoms.

Conclusion：LS was a useful method to fix C2 in cases of high riding vertebral artery.

Cervical disc herniation can be treated by anterior (A) and posterior (P) approach using percutaneous endoscopy(PE). We will discuss the indications, procedures and results between the two approaches. We have done 33 cases by A-approach and 8 cases from P-approach. A-approach is suitable for a herniation located inside the lateral edge of the spinal cord. P-approach is suitable for a herniation located outside the lateral edge of the spinal cord, sometimes extending into the foramen. The outcome was evaluated by Macnabʼs score and VAS in the neck and the upper extremity.

In the A-group, the outcome after initial operation was judged to be satisfactory in 29 patients and unsatisfactory in four. In one poor case, ACDF for removing bone spur was needed. Another poor outcome resulted from insufficient removal of the disk. However, this was treated conservatively with fair results. In another unsatisfactory case, a recurrent herniation occured two months after surgery, but after a second PECD surgery, the outcome was good. On the other hand, the result of Papproach was satisfactory in 7 cases and 1 case was fair which was treated by satellite ganglion blocks with good result.

Objective：Anterior cervical discectomy and fusion (ACDF) using cage fixation has been popular. In the present study, the authors attempted to verify the contemporary use of rectangular titanium stand-alone cage fixation.

Methods：The authors performed 175 ACDF procedures over the past 8 years. The present study included 47 consecutive patients who underwent ACDF and completed periodic and at least 1-year follow-up after surgery and whose imaging analysis was done on computerized medical records system.

Results：None of the patients developed surgery-related complications including cage displacement or extrusion. Overall analysis indicated significant improvement of functional recovery, and there was no significant difference between cage subsided and non-subsided groups. Twelve of 63 inserted cages(19.0%)were found to have cage subsidence. The fusion level, the cage size and the cage position had significant effects on cage subsidence. The distraction rate in the cage subsided group was significantly higher than the cage non-subsided group. Cage subsidence resulted in the early deterioration of local angle as well as C2-7 angle.

Conclusion：A surgical outcome with negligible complications appears to justify the contemporary use of a rectangular titanium stand-alone cage. The distraction rate and cage position were important to minimize the cage subsidence.

The purpose of this report is to evaluate the clinical outcomes of anterior cervical discectomy and fusions(ADF)for patients with residual symptoms after posterior decompression surgeries.

Method：There were 20 patients. The mean age was 61.0 years old. Every previous operation(17 laminoplasties and 3 laminectomies)had been done in other hospitals. They had some residual symptoms including cervical radiculo-myelopathies,autonomic nervous symptoms and axial pain. The x-ray showed decreased C2-C7 angle with 6.4 mean values. The spinal cord compressions were found in 16 patients in MRI studies and T2W high intensities were found in 11 patients. We performed microsurgical anterior decompressions followed by anterior fusion using titanium mesh cages with anterior plating system. The mean period from previous surgeries to the second surgeries was 50.8 months.

Results：The clinical results were evaluated with VAS,JOA score and SF36. The mean followup period was 1.9 years(5.0-1.0). VAS was improved from 6.6 to 3.4cm in average. The recovery rate in JOA score was 55.7%. Every scale of SF36 was statistically improved(p＜0.01). The autonomic nervous symptoms were improved in 73% and axial pains were improved in 64%. The C2-C7 mean angle was improved to 30 degree

Two cases of severe cervical kyphosis treated by C7 pedicle subtraction osteotomy(PSO)are reported. The patients were both 83-years-old, one male(case 1)and one female(case 2), who complained of difficulties in anterior gazing and walking.

Radiographic measurements were as follows, the tilting angle(TA)of C2 and C6 end plate, C2-6 kyphosis angle(KA), and sagittal vertical axis(SVA)which was defined as the distance between C2 and C6 plumb line.

Followingtwo-stag ed anterior and posterior operations includingC 7 PSO, each measurement improved；C2- TA, 7°→15°；C6- TA, 50°→25°；KA, 2°→−10°；SVA, 77mm→30mm, respectively in case 1. Such improvements were also achieved in case 2；C2- TA, 70°→14°；C6- TA, 27°→−6°；KA, 43°→20°；SVA, 60mm→mm. The patients were satisfied with their postoperative anterior gazing and walking.

Local correction angle at C7 after PSO was 33°and 29°, which were comparable to that of conventional PSO in lumbar spine. These results suggest that C7 PSO is an effective treatment of severe cervical kyphosis.

Purpose：The purpose of this study was to investigate lethal complications after spinal surgeries and facilitate preoperative informed consent.

Patients and methods：Patients undergoing spinal surgeries from April 1997 to March 2011 were examined. Fatal complications and major implant failures were searched for and evaluated.

Results：Among 1809 spinal surgery cases, 11 patients showed fatal complications(6 male, 5 female, Ave. 68 years old；30-88) Nine of 11 cases died of acute upper airway obstruction, pneumonia, heart failure, cerebrovascular events, and pulmonary embolism during the perioperative period. One patient with upper airway obstruction following massive tongue swelling after craniocervical tumor excition was saved by emergency tracheotomy. A broken posterior Luque rod penetrated into the rectum through the sacrum in the other thoracolumber fracture case.

Conclusion：There were 2 types of fatal complications, predictable and unpredictable. It might be possible to prevent predictable complications by meticulous perioperative management. Preoperative information to the patients should contain the potential of fatal complications.

Though postoperative C5 palsy is a common complication after cervical spine surgery, the cause is still unclear. We experienced two cases that presented C5 palsy after thoracolumbar surgery.

Case 1：A 70-year-old male. T10-12OLF surgery and L3/4 laminectomy was performed. Three days after surgery, deltoid and biceps muscle weakness developed and the MMT was 2. X-ray demonstrated a narrow spinal canal from C5 to C7. MRI revealed a bone spur in C5/6 foramen. After 7 months, muscle weakness recovered to MMT of 5.

Case 2：74-year-old male. L3-5PLIF was performed. 2 days after surgery, neck and shoulde pain appeared. MMT of the deltoid was 2 and biceps was 3. X-ray showed narrowing of intervertebral spaces at C3/4 and C4/5 levels, with no instability. MRI revealed a bone spur at C4/5 foramen. 6 months after, muscle weakness had recovered completely. 1 year after, reoperation was performed with more cervical flexion than usual. C5 palsy did not occur.

Discussion：Nerve root impairment may be caused by cervical position during the operation. These cases also suggest that the C5 nerve root is very vulnerable so that any small stress can cause C5 palsy.

It is necessary to pay close attention to the cervical position during any surgery.

The possibility of intraoperative monitoring for postoperative neurological recovery of compressive spinal or radicular disorders by transcranial motor evoked potential (TCMEP) is discussed. TCMEP monitorings have been performed during 125 spinal operations for compressive spinal or radicular disorders. TCMEP monitorings were evoked by 200 to 600 V transcranial stimulations and recorded by electromyograms. TCMEP amplitudes were compensated by compound muscle action potential(CMAP)after peripheral nerve stimulation. In 125 operations for spinal or radicular compressive disorders, the mean relative amplitude after CMAP compensation in the excellent(E)postoperative result group(Recovery rate of Japan Orthopedic association score more than 50%)was significantly higher than that in other groups(p=0.0088). All patients whose relative amplitude index with CMAP compensation had been more than 1.2 achieved postoperative neurological recovery. It seemed that if the relative amplitude index with compensation by CMAP after peripheral nerve stimulation was more than 1.2, neurological recovery was certainly expected.

The pathology of lumbar spinal stenosis depends largely on dynamic factors, and the stenosis is relieved in flexion and exacerbated in extension. Interspinous process decompression with the XSTOPimplant (X-STOPprocedure )is a surgical technique intended to limit intervertebral extension by placing an implant between the spinous processes, indirectly achieving nerve decompression with no manipulation within the spinal canal. The X-STOP^®PEEK, which has been covered by insurance since 2011, uses the PEEK-OPTIMA^®on its contact zone with the spinous processes to reduce the load on the spinous processes by load distribution. Since the use of this new implant is currently permitted in limited medical institutions, there have been a limited number of patients treated with this implant in Japan. We performed the X-STOPprocedure using the X-STOP^®PEEK in two male patients aged 70 years old on average, with mean operation time of 27 minutes and the amount of bleeding of 10ml. The mean JOA score increased from 18 points before surgery to 27 points at the seventh day after surgery. Symptoms improved markedly immediately after surgery as shown by decreases in the mean VAS scores from 86 to 3 for lower leg pain. The mean postoperative length of stay was 2.5 days and mean follow up period was 6.3 months. Although long-term follow-up is required, this procedure will probably be the treatment of choice for selected patients with lumbar spinal stenosis.

Hemangioblastomas are reddish on the surface, because they have a high blood flow and so are prone to easy bleeding.Furthermore hemangioblastomas have two important features which are that most(more than 90%)are located dorsal to the dentate ligament and in the extramedullary space (nerve root or posterior horn).Our case is a 68year-old female.She presented with paraplegia.MRI showed a massive tumor with many flow voids located between C7 and T2, whose features were consistent with hemangioblastoma.A two step operation was selected.On the basis of the above features, the reddish tumor surface was coagulated to reduce the tumor size.The arteries supplying the tumor were identified using micro-doppler and then cut.Only the extramedullary part of the tumor was removed.The second operation was performed when the cord swelling had subsided.The extramedullary tumor originated from the right T2 radicular nerve and the subpial hemangioblastoma extruded into the subdural space which formed the whole spinal hemangioblastoma. Discussion：Multiple step operations should be chosen to treat large hemangiobastomas with cord edema, because protection of the spinal cord and orientation between tumor and cord is difficult.

Objective:We present our surgical experience of lateral approach to the craniovertebral junction and discuss its indications and avoidance of complications.

Methods：The patient was placed in the lateral park-bench position. Retroauricular incision was made to expose the transverse process of C1. Subperiosteal muscle dissection resulted in the exposure of the lateral part of C1 and C2 and suboccipital condylar fossa. The vertebral artery running on the vascular groove of C1 was identified. The horizontal segment of the vertebral artery can be transposed byopening the C1 transverse foramen, if necessary.

Case 1:A 60-year-old male presented with gait disturbance and clumsy hands. MRI showed an intradural cystic tumor at C1 ventral side. Total removal of the cystic tumor was successfully done using the lateral approach. Pathological diagnosis of synovial cyst was determined.

Case 2:A 65-year-old male presented with severe neck pain on the right side. MRI showed extensive invasion of a tumor at C1 on the right side. Partial removal of the tumor was successfully done using the lateral approach. Pathological diagnosis of clear cell carcinoma was determined.

Conclusion:Lateral approach to the craniovertebral junction can be applied successfullyin selected cases such as tumors with ventral or lateral extension.

The purpose of this study is to elucidate the significance in preservation of C7 or C6 posterior arches with their attachments of the nuchal ligament in order to maintain cervical curvature and to reduce neck pain after posterior cervical spine surgeries. In previous papers which emphasized the significance in preserving the integrity of the C7 posterior arch with its attachment of the nuchal ligament, results were compared between C3-7 laminoplasty and C3-6 laminoplasty. Their study designs were unsatisfactory because the former is more invasive of the posterior stabilizing structures than the latter. We compared surgical results between the groups which had the same amount of surgical invasion to the posterior stabilizing structures. There was no statistical difference in pre- and postoperative cervical alignment and neck pain between cases with the posterior arches and their ligament attachments sacrificed and those preserved. These results suggested that preservation of the integrity of the cervical posterior arches with their attachments of the nuchal ligament does not have greater influence over postoperative neck pains and cervical curvature.

Introduction：Transvertebral anterior foraminotomy is less invasive compared to an anterior
cervical decompression and fixation. However, it is not easy to make a small hole in the direction of the nerve root without becoming disorientated. We report our ideas for a safe operation.

Method：The approach side is same as the decompression side. We approach the vertebra with the usual method. Foraminotomy is made at the inferiolateral side of the upper vertebra. Injury of the disc and endplate may lead to scoliosis or loss of disc height in the future. Maximum preservation of these structures is of utmost importance, so the foraminotomy should be toward the nerve root without disorientation. Contrast medium filled in the foramen is a useful navigator to ensure the correct direction. Then, we remove the disc hernia and spur. Pooling of contrast medium behind the vertebra suggests the nerve root has been decompressed.

Result：We have experienced 12 cases. Appropriate foramens were made in all cases.

Conclusion：These inventions could contribute to increased safety of the operation.

Purpose：We report our technique for lateral mass screw insertion of the middle and lower cervical spine for posterior fixation.

Patients and Methods：Since February 2002, thirty-nine patients have undergone posterior fixation usinglateral mass screw of the middle and lower cervical spine. The screw entrance point wasmm medial and caudal to the posterior center of the lateral mass, and orientation of the screw was 15 to 25 degrees lateral and towards the rostral side of the posterior ridge of the transverse process. Lateral mass fractures associated with screw insertion can occur in some elderly patients.
We therefore made several modifications to the technique as follows：
1. Measuring the ideal screw angle in each case by using the originally designed devices and fluoroscopy.
2. Preparinga crescent-shaped screw hole and drillingwith a 2-mm diamond bar to a depth of 10mm to decrease the screw shift toward the lateral and rostral side duringscrew drilling.
3. Maintainingmobility of the screw head to avoid excessive load on the lateral mass during fixation.

Results：A total of 203 lateral mass screws were placed without any neurovascular complications. There is no lateral mass fracture associated with screw insertion after usingour modified techniques.

Conclusion：Our technique will help to avoid lateral mass fractures associated with screw insertion in the middle and lower cervical spine.

C5 palsy is a well-known complication of cervical laminoplasty. We have reported that the incidence of C5 palsy decreased by the use of prophylactic bilateral C4-5 foraminotomy(PBF). However, in PBF, there are potential risks for postoperative segmental instability and axial pain because a part of the facet joint is removed. The purpose of this study is to investigate the influence of PBF on postoperative segmental instability and axial pain. Twenty-six patients with cervical spondylotic myelopathy (CSM) who underwent open-door laminoplasty (LP) with PBF were enrolled in the present study as the PBF group. The control group consisted of 24 patients with CSM who underwent LPwithout foraminotomy. There were no significant differences in sex, age and the number of opened laminae between both groups. As compared with the control group, segmental instability did not develop in the PBF group. At all collection times, there were no significant differences in VAS of axial pain, JOA score between both groups. In conclusion, PBF would be acceptable as a prophylactic procedure of C5 palsy because PBF did not cause the cervical malalignment, segmental instability and axial pain.

Purpose：We are performing laminoplasty using the multi-spacer which was introduced by Kihara et al. The purpose of this study is to report our experience and clinical outcome of laminoplasty using this multi-spacer.

Material：Among spinal surgeries performed from January 2010 to August 2011, 17 patients underwent this surgical procedure and were studied.

Result：The etiological diagnoses were spinal cord tumor(n=5),Chiari malformation type I(n=3), cervical spondylotic myelopathy CSM (n=6),and lumbar canal stenosis LCS (n=3). Postoperatively,adequate decompression was achieved and early radiological follow up was uneventful. There were no problems such as slippage or sinking of spacers observed. In duralplasty cases,it was convenient for dural tenting.

Discussion：Laminoplasty using the multi-spacer was safe. It produced reliable decompression and secured reconstruction of lamina. Indeed,the short-term outcome was good. This procedure is considered of value in these cases. However,the long-term outcomes still need to be studied in the future.

Purpose：To examine the relationship between preoperative symptoms and surgical outcomes in lumbar spinal canal stenosis (LSCS).

Patients：Among the patients who underwent laminectomy over the past 4 years, twenty-five patients had mainly numbness in the lower extremities (LE) as the preoperative complaint (S group： 12 males, 13 females. 75.1 years old, follow-up period of 7.2 months, and number ofoperated lamina of 2.4 on average). Eighteen patients had mainly pain in LE (T group：8 males, 10 females. 73.4 years old, follow-up of 10.7 months, and number ofoperated lamina of 2.3 on average). All patients had intermittent claudication (IC), negative SLR, and imaging findings of canal stenosis on MRI.

Results：There were 5 patients (20%) in S group and none (0%) in T group with preoperative bladder bowel disturbance, and 1 (4%) in S group and 7 (39%) in T group with resected disc herniation. There were significant differences between them (P‹0.05).
Discussion and conclusion：About forty percent of patients whose preoperative complaint is mainly pain in LE have disc herniation despite negative SLR. Therefore it is important to explore and visualize each nerve root clearly as is done in laminectomy.

We evaluated new oblique MRI for L5 root foraminal and extraforaminal stenosis. We were able to diagnose 4 cases of extracanal stenosis by oblique MRI and confirmed L5 root compression at the time of operation. In one case, it was difficult to remove the artifacts of instrumentation. The oblique MRI is considered to be useful for L5 extracanal stenosis. We recommend oblique MRI for L5 extracanal stenosis as a simple and less invasive imaging modality.

Objective：To investigate the incidence of facet cysts after hemi-laminotomy of the lumbar spine.

Method：The subjects were 101 patients who underwent magnetic resonance imaging (MRI) after hemi-laminotomy of the lumbar spine between July 2006 and February 2011. Among the patients, 66 had lumbar canal stenosis and 24 had lumbar spondylotic listhesis and one had hemorrhage of the yellowligament.

Result：Facet cysts were observed in 14 patients. We classified them into 3 groups according to the size[measurement of width (mm) ×length (mm) as an approximate value]of cyst on MRI：large (>40mm²;4 patients), medium(20-39mm²;2 patients), small (<20mm²;4 patients). The severities of patientsʼ symptoms were correlated to the size of the cyst. We also classified them into 3 groups according to the severity of osteoarthritis(OA)of the facet joint on CT：grade 1 (mild), grade 2 (moderate), grade 3 (severe). Four of 6 patients with large cysts indicated severe OA, and 4 of 6 patients with small cysts indicated mild OA.

Conclusion：This analysis of a small number of patients showed that postoperative facet cysts tend to be larger with increasing severity of facet OA.

We present a case of syringomyelia and syringobulbia treated by fourth ventricle-syringo shunt.
A 39-year-old female had meningitis 15 years ago for which ventriculo-peritoneal shunts were performed several times. She has had paraplegia of the lower extremities for the last 12 years. 7 years ago,she had monoparesis and pain of the left upper extremity. MRI at that time showed syringomyelia and syringobulbia. The syringo-peritoneal shunt was performed and the syrinx was transiently reduced in size. 18 months ago,she developed dysarthria,dysphagia and monoparesis of right upper extremity. Follow-up MRI indicated extended syringobulbia,so the fourth ventriclesyringo shunt was performed with suboccipital craniotomy. After this operation,her symptoms improved.

Objective：To evaluate radiation exposure dose affecting residents and senior doctors in myelography and nerve block treatment.

Methods：Over and under-table tube fluoroscopy systems were used. The radiation exposure dose was monitored at the breast and the wrist level.

Results：

Myelography：The exposure doses at the breast level of residents and senior doctors were 56.0 mSv and 3.8mSv with over-table,and 12.8mSv and 4.3mSv with under-table. The exposure doses at the wrist level of residents and senior doctors were 118.9mSv and 2.3mSv with over-table,and 8.6 mSv and 0.3mSv with under-table.

Nerve block treatment：The exposure doses at the breast level of residents and senior doctors were 39.7mSv and 15.5mSv with over-table,and 9.1mSv and 1.8mSv with under-table. The exposure doses at the wrist level of residents and senior doctors were 26.3mSv and 4.6mSv with over-table, and 5.2mSv and 2.2mSv with under-table.

Discussion：

The exposure dose of residents was particularly high. Therefore,residents need to be especially careful about their radiation exposure.

Background：Frequent use of MRI has brought about an increase in the diagnosis of dural arteriovenous fistulae (dAVF). Utility of intraoperative indocyanine green (ICG) videography to substitute for intraoperative angiography has also been reported.

Objectives：To verify in operative cases that transdural ICG videography after laminectomy is useful for verification of laminectomy level and for designing the dural incision line.

Results：ICG intravenous injection and fluorescence videography has been performed intraoperatively in dAVF operations since April 2011. Dura mater of the spine is thin and half transparent, thus yielding the quality of videography almost as clear as that after opening the dura.
Comparing the ICG videography to preoperative angiography, it was possible to verify the laminectomy level and redesign the durotomy line if necessary. No adverse events or interference with repeated ICG videography just before or after the obliteration of the fistula have been encountered.

Conclusions：Utility of ICG videography for localization of intradural tumor before dural opening and for identification of intramedullary pathology or anatomic midline before myelotomy has been reported. ICG videography before dural opening was shown to be similarly useful for spinal vascular lesions, and may contribute to increasing the safety of operative treatments.

Objective：To investigate the efficacy of our navigation manual and new techniques in accurately placing cervical pedicle screws (CPS).

Methods：CT-based navigation surgery was started in May 2005 in our hospital. Iso-C 3D navigation system was introduced to obtain real-time images in 2009.A navigation manual for CPS was decided as follows；Step 1:Decision of entry point, Step 2:Confirmation of pedicle inclination,
Step 3:Confirmation of transverse foramen, Step 4:check the inside of pedicle on Probeʼs eye view.
All procedures of pedicle probing, tapping, and screw insertion were done through a Portal using a syringe technique, whereby a disposable syringe was put in another skin incision to keep an angle of 45 degrees.This navigation manual has been used since January 2010. 63 patients underwent cervical posterior instrumentation surgery with CPS and a total of 336 screws were inserted. 93 screws for 17 patients were inserted by this procedure in 2010.Deviation rate was evaluated by postoperative axial CT images.

Results：Recent deviation rate for 2010 was 1.0%；on the other hand, the former deviation rate from 2005 to 2009 was 6.7%.

Conclusion：Deviation rate of CPS was decreased to 1.0% in 2010 as a result of improvement of techniques such as the syringe technique and introduction of our navigation manual.