Advancements and Challenges in Robot-Assisted Bone Processing in Neurosurgical Procedures.

OBJECTIVE: Practical applications of nerve decompression using neurosurgical robots remain unexplored. Our ongoing research and development initiatives, utilizing industrial robots, aim to establish a secure and efficient neurosurgical robotic system. The principal objective of this study was to automate bone grinding, which is a pivotal component of neurosurgical procedures. METHODS: To achieve this goal, we integrated an endoscope system into a manipulator and conducted precision bone machining using a neurosurgical drill, recording the grinding resistance values across 3 axes. Our study encompassed 2 core tasks: linear grinding, such as laminectomy, and cylindrical grinding, such as foraminotomy, with each task yielding unique measurement data. RESULTS: In linear grinding, we observed a proportional increase in grinding resistance values in the machining direction with acceleration. This observation suggests that 3-axis resistance measurements are a valuable tool for gauging and predicting deep cortical penetration. However, problems occurred in cylindrical grinding, and a significant error of 10% was detected. The analysis revealed that multiple factors, including the tool tip efficiency, machining speed, teaching methods, and deflection in the robot arm and jig joints, contributed to this error. CONCLUSION: We successfully measured the resistance exerted on the tool tip during bone machining with a robotic arm across 3 axes. The resistance ranged from 3 to 8 Nm, with the measurement conducted at a processing speed approximately twice that of manual surgery performed by a surgeon. During the simulation of foraminotomy under endoscopic grinding conditions, we encountered a -10% error margin.

Fluid Lubrication and Cooling Effects in Diamond Grinding of Human Iliac Bone.

Background and Objectives: Although there have been research on bone cutting, there have been few research on bone grinding. This study reports the measurement results of the experimental system that simulated partial laminectomy in microscopic spine surgery. The purpose of this study was to examine the fluid lubrication and cooling in bone grinding, histological characteristics of workpieces, and differences in grinding between manual and milling machines. Materials and Methods: Thiel-fixed human iliac bones were used as workpieces. A neurosurgical microdrill was used as a drill system. The workpieces were fixed to a 4-component piezo-electric dynamometer and fixtures, which was used to measure the triaxial power during bone grinding. Grinding tasks were performed by manual activity and a small milling machine with or without water. Results: In bone grinding with 4-mm diameter diamond burs and water, reduction in the number of sudden increases in grinding resistance and cooling effect of over 100 °C were confirmed. Conclusion: Manual grinding may enable the control of the grinding speed and cutting depth while giving top priority to uniform torque on the work piece applied by tools. Observing the drill tip using a triaxial dynamometer in the quantification of surgery may provide useful data for the development of safety mechanisms to prevent a sudden deviation of the drill tip.

Finite element method for nerve root decompression in minimally invasive endoscopic spinal surgery.

INTRODUCTION: Diagnosis is the key to improving spinal surgery outcomes. Improvements in the diagnosis of radiculopathy have created new indications for full-endoscopic spine surgery. We assessed the finite element method (FEM) to visualize and digitize lesions not detected by conventional diagnostic imaging. METHODS: We used FEM in two patients: a lumbar patient and a cervical patient. The lumbar patient was a 67-year-old woman with a history of rheumatoid arthritis; she also had osteoporosis and pulmonary fibrosis. She had left L3 radiculopathy due to an L3 vertebral fracture. The cervical patient was a 61-year-old woman with left C6 radiculopathy due to C5-C6 disc herniation. We performed full endoscopic foraminotomy per the patients's request. Based on preoperative and postoperative CT Digital Imaging and Communications in Medicine data of 0.5-mm slices, 3-D imaging data were reproduced, and kinetic simulation of FEM was performed. RESULTS: Postoperatively, both patients' radiculopathy disappeared, improving their activities of daily living and enabling them to walk and work. Also, the total contact area and maximum contact pressure of the nerve tissue decreased from 30% to 80% and from 33% to 67%, respectively. CONCLUSIONS: A new method for perioperative evaluation and simulation, FEM can be to visualize and digitize the conditions of the lesion causing radiculopathy. FEM that can overcome both time and economic constraints in routine clinical practice is needed.

V-rod technique for direct repair surgery of pediatric lumbar spondylolysis combined with posterior apophyseal ring fracture.

We report a pediatric baseball player having both a fracture of the posterior ring apophysis and spondylolysis. He was presented to a primary care physician complaining of back pain and leg pain. Despite conservative treatment for 3 months, the pain did not subside. He was referred to our clinic, and surgical intervention was carried out. First, a bony fragment of the caudal L5 apophyseal ring was removed following fenestration at the L5-S interlaminal space, bilaterally: and decompression of the bilateral S1 nerve roots was confirmed. Next, pseudoarthrosis of the L5 pars was refreshed and pedicle screws were inserted bilaterally. A v-shaped rod was inserted beneath the L5 spinous process, which stabilized the pars defects. After the surgery, back pain and leg pain completely disappeared. In conclusion, the v-rod technique is appropriate for the spondylolysis direct repair surgery, especially, in case the loose lamina would have a partial laminotomy.

Percutaneous endoscopic transforaminal approach to decompress the lateral recess in an elderly patient with spinal canal stenosis, herniated nucleus pulposus and pulmonary comorbidities.

A 70-year-old man with severe pulmonary comorbidities was referred to our institution for treatment of a right L5 nerve impingement. He had suffered from spinal canal stenosis and herniated nucleus pulposus (HNP) at the level of L4-L5 for more than a year and had been treated conservatively. However, the pain could not be alleviated, and his primary care physician scheduled posterior decompression surgery. During this procedure, the anesthesiologist refused to induce general anesthesia because of the patient's very poor pulmonary condition. Subsequently, the patient was referred to us. We used a transforaminal approach with percutaneous endoscopic discectomy, with the patient under local anesthesia. First, herniated nucleus pulposus fragments at the disc level were removed. With a trephine drill, the upper part of the L5 pedicle was removed, which allowed for the extraction of dorsally migrated fragments. Following complete removal of the herniated nucleus pulposus fragments, osseous decompression was performed. The osseous endplate of L5 (anterior part of the lateral recess) was removed to enlarge the lateral recess so that decompression of the L5 nerve root was possible. The patient's lower back pain and right leg pain subsided following surgery. Percutaneous endoscopic discectomy is useful for patients with severe comorbidities as it can be done with local anesthesia.

Minimally invasive and simultaneous removal of herniated intracanal and extracanal lumbar nucleus pulposus with a percutaneous spinal endoscope.

Herniated nucleus pulposus (HNP) in the lumbar spine is usually found in the neural canal (in the intracanal space) and occasionally in the extracanal space, where it is known as a lateral HNP. HNP is rarely found simultaneously in both spaces. However, we experienced such a case in a 48-year-old man who presented with right leg pain and lower back pain that had lasted for more than a year. MRI revealed HNP in both the right intracanal and extracanal spaces at L2-L3. A transforaminal approach was used to complete a percutaneous endoscopic discectomy. An 8-mm incision was made with the patient under local anesthesia, and the percutaneous endoscope was inserted at the affected disc space. First, the HNP fragments in the intracanal space were removed, and then the cannula and endoscope were extracted to the extracanal space where the extracanal fragments were removed. Two hours after the surgery, the patient stood and walked. Right leg pain and lower back pain had disappeared. Unlike other techniques such as Love's procedure and the microendoscopic discectomy technique, the use of a transforaminal approach with the percutaneous endoscopic technique enables the HNP fragments in the intracanal and extracanal spaces to be removed at the same time with a single approach.

Disproportionately large communicating fourth ventricle associated with syringomyelia and intradural arachnoid cyst in the spinal cord successfully treated with additional shunting. Case report.

A 44-year-old woman presented with a rare case of disproportionately large communicating fourth ventricle (DLCFV) associated with syringomyelia and intradural arachnoid cyst in the spinal cord. Ventriculoperitoneal shunt operation was performed for hydrocephalus after subarachnoid hemorrhage. She developed DLCFV, which was then associated with syringomyelia and spinal intradural arachnoid cyst. Shunting of the fourth ventricle improved DLCFV, and then the syringomyelia and arachnoid cyst. Although the aqueduct was patent, independent pressure control of the fourth ventricle and the other ventricles was necessary to improve the symptoms. Shunting of the fourth ventricle should be considered for patients with DLCFV when the symptoms persist despite adequate pressure control of the other ventricles.

Clinical outcomes and adverse events following transforaminal interbody fusion for lumbar degenerative spondylolisthesis in elderly patients.

Transforaminal lumbar interbody fusion (TLIF) procedure is widely used, but the surgical indications for TLIF in elderly patients remain controversial because of potential risks such as inferior bone quality and higher rate of postoperative complications. Clinical efficacy and operative risk of TLIF in elderly patients are unclear. This study investigated the clinical effect and safety of TLIF for lumbar degenerative spondylolisthesis with radiculopathy or neurogenic claudication in patients aged 70 years or older. The clinical records were retrospectively reviewed of 35 consecutive patients aged 70-86 years (mean 74.8 years) who underwent one or two-level TLIF. The preoperative diagnosis included degenerative spondylolisthesis with segmental instability. Clinical outcomes were assessed by the Japanese Orthopaedic Association score, visual analogue scale, Oswestry Disability Index. Radiological fusion rate was also investigated. Clinical and radiological results were compared with those of 43 younger patients. Clinical outcome measures were significantly improved after operation in the elderly patients, but improvement rates were significantly lower than those of younger patients. Fusion rate was similar in both groups. Overall postoperative complications were increased in aged patients, although the prevalence of complications directly related to surgical technique was not significantly increased. Postoperative complications not related to the surgical procedure were factors affecting poor results. TLIF is acceptable for achieving clinical recovery and lumbar fusion with high radiographic fusion success even in elderly patients, although clinical benefits were limited compared with those of younger patients. Postoperative morbidity was mainly related to general or non-operative site complications.

Lumbar discal cyst with spontaneous regression and subsequent occurrence of lumbar disc herniation.

A 39-year-old man presented with an extremely rare discal cyst at the L3-4 level manifesting as a left L4 radiculopathy. Two months after onset, he suffered right L4 radiculopathy with new lumbar disc protrusion. Five months after medical treatment, the patient's symptoms improved, and the discal cyst showed complete regression on magnetic resonance imaging. Most cases of discal cyst are surgically treated, with only two previous cases of spontaneous regression. The present case suggests clinical and radiological recovery of symptomatic lumbar discal cyst can be obtained by only conservative therapy.

[Investigation of pseudolocalizing signs in the lumbar region: analysis of L5 monoradiculopathy due to upper lumbar compressive lesions].

BACKGROUND AND PURPOSE: Pseudolocalizing signs in lumbar spinal disease seems to be rarely encountered. To our knowledge, only six cases which caused L5 monoradiculopathy due to upper lumbar lesions have been described. We retrospectively reviewed patients with similar signs in our center, and we discussed the pathogenesis of such interesting neurological signs depending on our own and reported cases. RESULTS: Between January, 2005 and August, 2010, 1,229 patients with lumbar degenerative disease underwent spinal decompression surgery, 3 of which (0.24%) presented with L5 monoradiculopathy due to upper compressive lesions in lumbar spinal disease. DISCUSSION AND CONCLUSION: As pathological mechanisms, 2 hypotheses are speculated: Direct compression at the epiconus level or circulatory disturbance at the nerve root itself. If the level of the conus medullaris is situated at the lower lumbar level, such as L2 level, a compressive lesion at the L1-2 level, for example lumbar disc herniation, can compress the L5 nerve root resulting in L5 nerve palsy. However, the affected level below the cauda equina doesn't seem to compress only the L5 nerve root directly, because the cauda equina is mobile enough to avoid the compression. Another speculated mechanism is the so-called circulatory disturbance. When the cauda equina is remarkably compressed at the upper level, less severe compressive change may cause selective monoradiculopathy at the lower lumbar level. Based upon the presented analyses, we adopt the circulatory mechanism in our cases as the causative factor in lumbar pseudolocalizing signs.

Paraplegia caused by intratumoral hemorrhage within thoracic epidural granuloma.

An 84-year-old man presented with a rare case of spinal epidural granuloma with intratumoral hematoma resulting in acute paraplegia. He was admitted to our hospital because of lumbago and hematemesis following a fall 10 days before. Progressive paraparesis occurred 2 days after admission. Neurological examination showed paraplegia and hypesthesia below the T10 level. Thoracic radiography revealed some spondylotic changes of the thoracic vertebrae without osteolytic changes. Sagittal T(1)- and T(2)-weighted magnetic resonance imaging of the thoracic spine demonstrated a hyperintense epidural mass lesion compressing the dorsal portion of the thoracic spinal cord at T10-11 space. Emergency laminectomy was performed, and the epidural encapsulated hematoma and elastic yellowish mass adhered to the dura mater were totally removed. Histological examination of the excised specimens showed a granuloma. Motor weakness improved after surgery, and he could walk with a cane about 3 months after surgery. The minor spinal injury probably caused intratumoral hemorrhage within a previous epidural granuloma, suddenly resulting in the paraplegic symptoms.

Spinal dural arteriovenous fistula with hematomyelia caused by intraparenchymal varix of draining vein.

BACKGROUND CONTEXT: Hemorrhage that results from spinal dural arteriovenous fistula (Type I arteriovenous malformation [AVM]) is uncommon. There are some reports of subarachnoid hemorrhage and subdural hematoma caused by Type I spinal AVM, but there are few reported cases of hematomyelia caused by spinal dural arteriovenous fistula. PURPOSE: To describe an interesting patient who had hematomyelia caused by a dural arteriovenous fistula (Type I spinal AVM). STUDY DESIGN: A case report. METHODS: We present a case of a 51-year-old man who presented acute onset epigastric pain, paraplegia, and sensory loss below his nipples. Magnetic resonance imaging and selective spinal angiogram demonstrated hematomyelia, subarachnoid hemorrhage, and spinal arteriovenous fistula fed by the right Th7 intercostal artery. By laminotomy of Th6-8, the varix-like draining vein and intramedurally hematoma were partially removed and the arterial supply was interrupted by coagulation of the right Th7 segmental artery. RESULTS: One month after surgery, he regained movement against gravity at the left ankle and toe but no functionally significant improvement. CONCLUSIONS: It must be kept in mind that spinal dural arteriovenous fistulas (Type I spinal AVM) has possibility of hematomyelia origin, despite the fact that it is extremely rare.

Osteoma arising from the lumbar articular process.

A 57-year-old man presented with an extremely rare osteoma originating from the left L-5 inferior articular process and causing lumbo-crural sciatica. Postmyelography computed tomography and magnetic resonance imaging showed an osteoma compressing the spinal nerve root at the lateral recess. Decompression facetectomy and excision of the lesion followed by transforaminal lumbar interbody fusion between L-5 and S-1 provided complete relief from the symptoms. Histological examination confirmed the diagnosis of benign osteoma. The previous seven cases of spinal osteoma involved the vertebral body, pedicle and posterior elements. Spinal osteomas should be considered in the differential diagnosis of benign lesion originating from the articular process.