Shunji Asamoto

Spinal chronic subdural hematoma in association with anticoagulant therapy: a case report and literature review.

Study Design. A case of spinal chronic subdural hematoma (SCSDH) in association with anticoagulant therapy was treated surgically. Objective. To clarify the etiopathogenesis, clinical presentation, and surgical outcomes of SCSDH. Summary of Background Data. Intracranial chronic subdural hematoma is a well-recognized complication of anticoagulant therapy. However, SCSDH is very rare and its etiopathogenesis is uncertain. Methods. A 72-year-old man with SCSDH who had received anticoagulant therapy for atrial fibrillation complained of bilateral lower extremity pain, cramps, and gait disturbance. The patient underwent an operation for evacuation of the hematoma. Results. Lower-extremity pain, cramps, and gait disturbance improved, and the patient was discharged 10 days after surgery. Conclusion. SCSDH should be included in the differential diagnosis of progressive spinal cord and nerve root compression in patients receiving anticoagulant therapy. Prompt diagnosis and early surgical decompression lead to a good outcome.

Cortical bone trajectory and traditional trajectory—a radiological evaluation of screw-bone contact

BackgroundCortical bone trajectory (CBT), a relatively new technique for pedicle screw insertion in the lumbar spine, is believed to have equivalent pullout and toggle characteristics compared with the traditional trajectory (TT). It has been hypothesized that the new trajectory offers higher cortical bone contact with the pedicle screws and therefore has an improved anchoring property over the traditional trajectory where the screws are inserted into the vertebral body trabecular space. The aim of this study is to evaluate the pedicle screw-cortical bone contact between the two trajectories from a radiological standpoint.MethodsTwo hundred twenty-two patients with degenerative lumbar spine disease underwent computed tomography scanning. For each patient, axial slices of the L4 and L5 vertebra were cut in two planes, one horizontal to the pedicle representing the plane at which pedicle screws are inserted using the TT and another in a more caudo-cranialxa0plane representing the plane at which pedicle screws are inserted using CBT. For each trajectory, a region of interest (ROI) was selected within the area in which the screws are inserted. A CT number (Hounsfield scale) was then calculated within each ROI to compare the bone density.ResultsThe CT numbers within the ROI for CBT were constantly almost over four times higher than that for the TT, and there was a significant difference between the values (pu2009<u20090.0001).ConclusionsThis study has demonstrated that, with the cortical bone trajectory, the pedicle screws penetrate a region that is richer in cortical bone compared to when using the traditional trajectory. This is in keeping with previous hypotheses that the new trajectory offers higher cortical bone contact.

Diagnosis and surgical strategy for sacral meningeal cysts with check-valve mechanism: technical note

ObjectiveThere is agreement that symptomatic sacral meningeal cysts with a check-valve mechanism and/or large cysts representing space-occupying lesions should be treated surgically. This study investigated factors indicating a need for surgical intervention and surgical techniques for sacral meningeal cysts with a check-valve mechanism.MethodsIn ten patients presenting with sciatica and neurological deficits, myelography, computed tomography (CT) myelography, and magnetic resonance imaging (MR imaging) detected sacral meningeal cysts with a check-valve mechanism. One patient had two primary cysts. Ten cysts were type 2 and one cyst was type 1. Nine of the ten patients had not undergone previous surgery, while the remaining case involved recurrent cyst. For the seven patients with normal (i.e., not huge or recurrent) type 2 cysts and no previous surgery (eight cysts), suture after collapse of the cyst wall was performed. For the recurrent type 2 cyst, duraplasty and suture with collapse of the cyst wall were performed to eliminate the check-valve mechanism. For the remaining type 2 cyst, a primary root was sacrificed because of the huge size of the cyst. For the type 1 cyst, the neck of the cyst was ligated.ResultsIn all cases, chief complaints disappeared immediately postoperatively and no deterioration of clinical symptoms has been seen after a mean follow-up of 27xa0months.ConclusionsThe presence or absence of a check-valve mechanism is very important in determining the need for surgical intervention for sacral meningeal cysts.

Novel surgical management of spinal adhesive arachnoiditis by arachnoid microdissection and ventriculo–subarachnoid shunting

Spinal cord tethering and cerebrospinal fluid (CSF) flow disturbance are two major features in the pathophysiology of spinal adhesive arachnoiditis. We hypothesized that insufficient CSF supply to the surgically untethered spinal cord may be one of the causes of the typical post-operative recurrent extensive lesion. We report a patient with extensive spinal adhesive arachnoiditis, who was successfully treated using a novel surgical technique consisting of two procedures. First, microdissection of the thickened adherent arachnoid was performed to resolve spinal cord tethering. Next, a ventriculo-subarachnoid shunt was placed to provide sufficient flow of CSF. Clinical improvement was sustained for at least 22 months after surgery. The present surgical procedure may improve clinical outcome in patients with longitudinally extensive spinal adhesive arachnoiditis.

Neurosurgeons in Japan Are Exclusively Brain Surgeons

BACKGROUNDnIn Japan, neurosurgeons have traditionally mainly treated brain diseases, with most cases involving the spine and spinal diseases historically being treated by orthopedists. Nowadays, spinal surgery is 1 of the many subspecialties in the neurosurgical field in Japan.nnnMETHODSnMost patients with neurological deficits or suspected neurological diseases see board-certified neurosurgeons directly in Japan, not through referrals from family physicians or specialists in other fields.nnnRESULTSnProblems originating in the spine and spinal cord have been overlooked or misdiagnosed in these situations.nnnCONCLUSIONSnNeurosurgeons in Japan must rethink the educational program to include advanced trauma life support and spinal surgery.

Optimized Screw Trajectory for Lumbar Cortical Bone Trajectory Pedicle Screws Based on Clinical Outcome: Evidence Favoring the Buttress Effect Theory

Background Cortical bone trajectory (CBT) is a relatively new technique for pedicle screw insertion in the field of spine surgery. Previous studies have demonstrated the significantly better pullout and toggle characteristics the new method offers, and it appears to have certain advantages over the widely used traditional trajectory. The mechanism of the pullout and toggle characteristics still remains unknown. Purpose To report the medium‐ to long‐term follow‐up findings of patients who underwent posterior lumbar interbody fusion or posterior lumbar fusion (PLIF/PLF) at our institution and to discuss the ideal screw trajectory when using this technique. Study Design Retrospective radiologic study. Methods Fifty‐five patients who underwent PLIF/PLF for lumbar spondylosis using the new technique between January 2011 and January 2016 were included. Clinical outcome was assessed using the Japanese Orthopaedic Association scores for low back pain and visual analog scale scores. Screw loosening was evaluated via the presence of a translucent zone surrounding the pedicle screw using plain X‐radiography (Xp). The screw trajectory was evaluated by measuring the rostral range (RR) and the lateral range score (LRS). The RR is the angle between the line drawn along the distal end plate of the vertebra and the line drawn along the screw on the lateral view. The LRS is the score given depending on the position of the tip of the screw seen on the Xp taken in the anteroposterior (AP) view. The pedicle ring is equally divided into the medial third (zone A), central third (zone B), and the lateral third (zone C) by four vertical lines. A score of 0 to 3 points is given depending on the position of the tip of the screw: 0, outside the pedicle ring; 1, zone A; 2, zone B; and 3, zone C. Results Bone fusion was recorded in 49 patients (49/55 patients). The total number of screws with a visible translucent zone on Xp was 26 (26/242 screws). When the screws are inserted at a more acute angle in the lateral view (low RR) or when the screws are directed more medially (low LRS), the risk of developing a translucent zone around the pedicle screw increased. Conclusion With CBT, the pedicle screws are inserted from the pars interarticularis that is rich in cortical bone, strong enough to withstand the substantial forces usually encountered in the region. Our clinical data suggest that the optimal screw trajectory is one where the screw is inserted at an angle > 22.55 degrees (high RR) on the lateral view Xp and where the tip of the screw is directed toward the lateral third of the pedicle on the AP Xp. We believe the naturally occurring buttress effect that exists in the vertebra may give CBT a mechanical and anatomical advantage over the traditional screw trajectory.

Bilateral fracture of the superior articular process of S1 - An unusual fracture seen in a speed skater.

Abstract Background Fractures of the superior articular process are rarely seen in clinical practice. Repetitive spinal movements may lead to fractures of the pars interarticularis, resulting in spondylolysis. Traumatic spinal fractures often involve the vertebral body, transvers and/or the spinous processes. The superior articular processes, however, are seldom involved in both traumatic and stress-induced fractures. Purpose The purpose of this report is to present an unusual case of symptomatic bilateral fracture of the superior articular process of the sacrum in a 21-year-old speed skater. Study design This is a case report. Methods The patient was admitted for close observation after complaining of excruciating lower back pain and bilateral dysesthesia along the L5 nerve root. Post-myelography computed tomography (CT) revealed a bilateral facet joint deformity at L5/S1 and a bilateral fracture of the superior articular process of the sacrum. A facet joint block at the L5/S1 joint alleviated the pain, and a nerve root block at the L5 nerve root improved the dysesthesia. The patient underwent an L5/S1 decompression, whereby the nonunion bone fragments were removed, followed by a posterior lumbar inter-body fusion (PLIF) at L5/S1. Results The patient showed immediate improvement and returned to training six months post-operatively. Conclusion We have presented a case of bilateral fractures of the superior articular process of the sacrum in a speed skater. His presenting symptoms were similar to those found in patients with spondylolysis and the etiology appears to be similar. Surgical treatment was opted given his symptomatic relief from nerve root and facet joint blocks.

Modified Goel’s Methods for Basilar Impression: A Case Report with Literature

We report the case of a 57-year-old woman who had basilar impression manifesting as severe myelopathy and occipital neuralgia and was treated by distraction and fixation performed using a modification of Goel’s method. Magnetic resonance imaging (MRI) and computed tomography (CT) scans showed severe myelocompression by the dens of the axis from the ventral side and occipitalization of the atlas. After traction using a Halo vest, C1–2 facet distraction and fixation was performed in one stage using a modified Goel’s method. Although Goel et al. used a custom-made spacer to distract the facet joints, we used a threaded titanium cylindrical cage that was inserted into the joint to fix the C1–2 facet joint with posterior fixation from occipital bone to C5. Postoperatively, gradual symptomatic and neurological amelioration were observed. The atlantoaxial joints were bone-fused at 3 years post-operation. Distraction and fixation performed using this modified version of Goel’s method was effective for treating basilar invagination. The threaded titanium cylindrical cage provided adequate C1–2 space and strong initial fixation.

Minimally invasive space shuttle laminotomy for degenerative lumbar spinal canal stenosis

Study Design: Technical note. Objectives: To show microsurgical technique, considering the meticulous anatomy of the ligamentum flavum (LF). Background: Different methods are available for treating lumbar spinal canal stenosis (LSCS). A minimally invasive surgery, namely, space shuttle laminotomy, has recently been proposed. Here, we describe the surgical method for this novel technique. To conduct this surgery accurately, surgeons must have perfect knowledge of anatomy, especially regarding the LF. Materials and Methods and Results: We use this interlaminectomy technique for all cases of LSCS. All patients with LSCS recovered from their neurological deficits in shorter hoslital stays than regular laminectomy. Conclusion: Minimally invasive space shuttle laminotomy (MISSL), which involves a microsurgical technique, is a safe, complication-free procedure.