Minimally invasive spine surgery: an animal model for endoscopic approach to the anterior cervical and upper thoracic spine

Intracranial Pressure Evaluation in Swine During Full-Endoscopic Lumbar Spine Surgery

BACKGROUND

Neurological complications during full-endoscopic spine surgery (FESS) might be attributed to intracranial pressure (ICP) increase due to continuous saline infusion (CSI). Understanding CSI and ICP correlation might modify irrigation pump usage. This study aimed to evaluate invasive ICP during interlaminar FESS; correlate ICP with irrigation pump parameters (IPPs); evaluate ICP during saline outflow occlusion, commonly used to control bleeding and improve the surgeon's view; and, after durotomy, simulate accidental dural tear.

METHODS

Five swine were monitored, submitted to total intravenous anesthesia, and positioned ventrally. A parenchymal catheter was installed through a skull burr for ICP monitoring. Lumbar interlaminar FESS was performed until exposure of neural structures. CSI was used within progressively higher IPPs (A [60 mm Hg, 350 mL/minute] to D [150 mm Hg, 700 mL/minute]), and ICP was documented. During each IPP, different situations were grouped: intact dura with open channels (A1-D1) or occlusion test (A2-D2); dural tear with open channels (Ax1-Dx1) or occlusion test (Ax2-Dx2). ICP <20 mm Hg was defined as safe.

RESULTS

Basal average ICP was 8.1 mm Hg. Adjustment in total intravenous anesthesia or suspension of tests was necessary due to critical ICP or animal discomfort. It was safe to operate with all IPPs with opened drainage channels (A1-D1) even with dural tear (Ax1-Dx1). Several occlusion tests (A2-D2, Ax2-Dx2) caused ICP increase (e.g., 86.1 mm Hg) influenced by anesthetic state and hemodynamics.

CONCLUSIONS

During FESS, CSI might critically raise ICP. Keeping drainage channels open, with ideal anesthetic state, ICP remains safe even with high IPPs, despite dural tear. Drainage occlusions can quickly raise ICP, being even more severe with higher IPPs. Total intravenous anesthesia may protect from ICP increase and may allow longer drainage occlusion or higher IPPs.

Identification of the Magna Radicular Artery Entry Foramen and Adamkiewicz System: Patient Selection for Open versus Full-Endoscopic Thoracic Spinal Decompression Surgery

BACKGROUND

Casually cauterizing the radicular magna during routine thoracic discectomy may have dire consequences.

METHODS

We performed a retrospective observational cohort study on patients scheduled for decompression of symptomatic thoracic herniated discs and spinal stenosis who underwent a preoperative computed tomography angiography (CTA) to assess the surgical risks by anatomically defining the foraminal entry level of the magna radicularis artery into the thoracic spinal cord and its relationship to the surgical level.

RESULTS

Fifteen patients aged 58.53 ± 19.57, ranging from 31 to 89 years, with an average follow-up of 30.13 ± 13.42 months, were enrolled in this observational cohort study. The mean preoperative VAS for axial back pain was VAS of 8.53 ± 2.06 and reduced to a postoperative VAS of 1.60 ± 0.92 (p < 0.0001) at the final follow-up. The Adamkiewicz was most frequently found at T10/11 (15.4%), T11/12 (23.1%), and T9/10 (30.8%). There were eight patients where the painful pathology was found far from the AKA foraminal entry-level (type 1), three patients with near location (type 2), and another four patients needing decompression at the foraminal (type 3) entry-level. In five of the fifteen patients, the magna radicularis entered the spinal canal on the ventral surface of the exiting nerve root through the neuroforamen at the surgical level requiring a change of surgical strategy to prevent injury to this important contributor to the spinal cord's blood supply.

CONCLUSIONS

The authors recommend stratifying patients according to the proximity of the magna radicularis artery to the compressive pathology with CTA to assess the surgical risk with targeted thoracic discectomy methods.

Patient selection criteria for percutaneous anterior cervical laser versus endoscopic discectomy

BACKGROUND

Percutaneous anterior laser and anterior endoscopic cervical spine surgery are associated with less approach trauma than conventional open cervical spine surgery. The literature illustrating their appropriate use corroborated with objective outcome evidence is scarce. The authors were interested in comparing the clinical outcomes following percutaneous laser disc decompression (PLDD) versus percutaneous endoscopic disc decompression (PEDD). © 2021 Wiley Periodicals LLC.

MATERIALS AND METHODS

Thirty patients with soft contained symptomatic cervical disc herniations and an average age of 50.5 years (range 26 - 68 years; 16 males and 14 females) were prospectively enrolled in 2 groups of 15 patients to be either treated with PLDD or PEDD. All patients underwent PLDD or PEDD under local anesthesia and sedation. Clinical outcomes were assessed with the Macnab criteria VAS score for arm pain. Complications and reoperations were recorded.

RESULTS

There were significant reductions in the VAS score for arm pain from preoperative 8.4 ± 2.5 to 3.1 ± 1.2 in the PLDD group (P < 0.03), and from preoperative 8.6 ± 2.7 to 2.4 ± 1.1 (P < 0.01) in the PEDD group. In the PLDD group, Macnab outcomes were excellent in 21% of patients, good in 44%, fair in 21%, and poor in 14%. In the PEDD group, Macnab outcomes were excellent in 14% of patients, good in 32%, fair in 12%, and poor in the remaining 12%. There were no statistically significant differences in clinical outcomes between the PLDD and the PEDD group. There were no approach-related or surgical complications.

CONCLUSIONS

Tissue trauma is significantly reduced with laser and endoscopic surgery techniques. PLDD and PEDD are both suitable for the specific indication of soft, symptomatic contained cervical disc herniations. The authors' small prospective cohort study indicates that PLDD and PEDD are options for cervical decompression surgery when medical comorbidities or preferences by patients and surgeons dictate more minimally invasive strategies.

Minimally invasive spine surgery decreases postoperative pain and inflammation for patients with lumbar spinal stenosis

In certain cases, lumbar spinal stenosis may lead to lumbar nervous disorder. A previous study indicated that minimally invasive spine surgery (MISS) presents benefits compared with conventional open surgery (COS). In the current study, the efficacy of MISS and COS for lumbar spinal stenosis patients was investigated. A total of 82 patients with lumbar spinal stenosis were enrolled and divided into two age-matched groups that received MISS (n=41) or COS (n=41). Patient parameters, including symptoms, inflammatory score, visual analog score (VAS), wound length, Oswestry Disability Index (ODI), hospital stay and postoperative outcomes were analyzed in the current study. Outcomes indicated that both MISS and COS significantly improved symptoms of lumbar spinal stenosis compared with the baseline. It was observed that MISS resulted in decreased wound length and hospital stay compared with COS for patients with lumbar spinal stenosis. The results revealed that MISS had better outcomes compared with COS in improving ODI and inflammatory score for patients with lumbar spinal stenosis. Notably, it was identified that MISS exhibited improved VAS for back and leg pain compared with the COS group for patients with lumbar spinal stenosis. In conclusion, these outcomes indicate that MISS was more effective compared with COS for improving symptoms in patients with lumbar stenosis.

Experimental Model for Interlaminar Endoscopic Spine Procedures

BACKGROUND

Endoscopic spinal surgery is becoming quite popular, and the pursuit of a training model to improve surgeons' skills is imperative to overcome the limited availability of human cadavers. Our goal was to determine whether the porcine spine could be a representative model for learning and practicing interlaminar percutaneous endoscopic lumbar procedures (IL-PELPs).

METHODS

Lumbar and cervical segments of the porcine cadaver spine were used for the IL-PELP. We have described the technical notes on the difficulties of the procedure and the relevant anatomical features. To endorse the porcine cadaver for this procedure, 5 neurosurgeons underwent 1 day of training and completed a survey.

RESULTS

The porcine lumbar spine has small interlaminar windows, and laminectomy is necessary, mimicking the translaminar approaches for higher human lumbar spine levels. The porcine cervical spine has wide and high interlaminar windows and mimics the human L5-S1 interlaminar approach. Entering the spinal canal with the working sheath and endoscope and training the rotation maneuver to access the disc space is only possible in the lumbar segment. It was possible to perform flavectomy and to identify and dissect the dural sac and nerve root in both the lumbar and cervical spine. The neurosurgeons considered the porcine model of good operability and, although different, possible to apply in humans.

CONCLUSIONS

The porcine spine is an effective and representative model for learning and practicing IL-PELPs. Although the described anatomical differences should be known, they did not interfere in performing the main surgical steps and maneuvers for IL-PELPs in the porcine model.

Cervical Deuk Laser Disc Repair(®): A novel, full-endoscopic surgical technique for the treatment of symptomatic cervical disc disease

Background:

Cervical Deuk Laser Disc Repair^® is a novel full-endoscopic, anterior cervical, trans-discal, motion preserving, laser assisted, nonfusion, outpatient surgical procedure to safely treat symptomatic cervical disc diseases including herniation, spondylosis, stenosis, and annular tears. Here we describe a new endoscopic approach to cervical disc disease that allows direct visualization of the posterior longitudinal ligament, posterior vertebral endplates, annulus, neuroforamina, and herniated disc fragments. All patients treated with Deuk Laser Disc Repair were also candidates for anterior cervical discectomy and fusion (ACDF).

Methods:

A total of 142 consecutive adult patients with symptomatic cervical disc disease underwent Deuk Laser Disc Repair during a 4-year period. This novel procedure incorporates a full-endoscopic selective partial decompressive discectomy, foraminoplasty, and posterior annular debridement. Postoperative complications and average volume of herniated disc fragments removed are reported.

Results:

All patients were successfully treated with cervical Deuk Laser Disc Repair. There were no postoperative complications. Average volume of herniated disc material removed was 0.09 ml.

Conclusions:

Potential benefits of Deuk Laser Disc Repair for symptomatic cervical disc disease include lower cost, smaller incision, nonfusion, preservation of segmental motion, outpatient, faster recovery, less postoperative analgesic use, fewer complications, no hardware failure, no pseudoarthrosis, no postoperative dysphagia, and no increased risk of adjacent segment disease as seen with fusion.

Extracervical approaches to endoscopic thyroid surgery

There is increasing demand for surgical procedures which avoid visible scars while maintaining optimal functional and ideal cosmetic results, without compromising the safety or effectiveness of the procedure. Endoscopic techniques have been adapted to abdominal and pelvic surgery and increasingly employed over the past three decades. Although hampered by the absence of a natural cavity, endoscopic techniques have been adapted to surgery in the neck for the past 15 years, particularly for the thyroid gland. While earlier attempts at endoscopic thyroid surgery were performed through incisions in or near the midline of the neck, recent techniques have been developed to place the incisions and endoscopic ports extracervically, or at least away from the midline region of the neck, rendering the cosmetic result more acceptable. Most of these approaches are through the axilla, breast, chest wall or a combination of approaches. Visualization of the thyroid and rate of complications with these approaches are equal to those attained with older endoscopic approaches. Careful patient selection is important for endoscopic surgery. Complications unique to the endoscopic approach are mostly related to insufflation of cervical tissues with pressurized CO(2).

Robotic approaches to the posterior spine

STUDY DESIGN

This anatomic study described robotic approaches to the posterior thoracolumbar spine in a porcine model. Ergonomics, control, and approach and technical difficulties were noted.

OBJECTIVE

The objective of this study was to develop a robotic approach to the posterior thoracolumbar spine maximizing surgeon ergonomics and control.

SUMMARY OF BACKGROUND DATA

Surgery is both physically and mentally demanding, and strains from ergonomics and the aging process may negatively impact surgical skills. In spine surgery, control and precision are extremely important due to the close proximity to the spinal cord. The da Vinci robotic surgery system has offered better ergonomics and control in urology, gynecology, and cardiac surgery, and is rapidly gaining adoption. To date, there have been no published reports of da Vinci robotic spine surgery, motivating us to assess its potential in posterior spine surgery.

METHODS

Posterior spine da Vinci approaches were tested on a pig without spinal pathology with an open subperiosteal dissection. A laser instrument and prototype robotic burr and rongeur instruments were tested on laminotomy, laminectomy, disc incision, and dural suturing procedures.

RESULTS

Open dissection of the posterior spine provided sufficient access to successfully perform laminotomy, laminectomy, disc incision, and dural suturing procedures. Prototype burr and rongeur instruments were effective with good control. The laser instrument coagulated the epidural venous plexus and incised the anulus. Robot ergonomics allowed the surgeon to perform procedures for a full day with significantly less fatigue and reduced hand tremor.

CONCLUSION

The da Vinci could perform the major noninstrumented procedures of the posterior spine with improved ergonomics and control. Surgeon fatigue and tremor were reduced. With some modification of prototype and commercial instruments a posterior spine surgery instrument kit can be developed. Future clinical studies can better assess patient and surgeon benefits of using the da Vinci robot for posterior spine surgeries.

Anterior cervical discectomy and interbody fusion by endoscopic approach: a preliminary report

OBJECT

The authors report the short-term results of anterior cervical discectomy and interbody fusion performed via an endoscopic approach.

METHODS

Thirty-six patients who underwent anterior cervical discectomy and fusion (ACDF) performed using endoscopic surgery were selected for this study. The indications for surgery were cervical disc herniation caused by neck injury, spondylotic myelopathy, cervical radiculopathy, and solitary ossification of the posterior longitudinal ligament (OPLL). The involved levels included C3-4, C4-5, C5-6, and C6-7. The working channel was inserted through a 20-mm transverse incision, the protruding discs or area of OPLL were excised for complete decompression, and then an appropriate intervertebral polyetheretherketone fusion cage was implanted.

RESULTS

The time spent in surgery was 120 minutes on average (range 50-150 minutes), and the mean blood loss was 55 ml (range 20-140 ml). There were no intraoperative complications and no symptoms of irritation in the laryngopharynx after surgery. However, postoperative hemorrhage of the incision occurred in 1 case. The follow-up period ranged from 26-50 months (mean 38.5 months). Postoperative Japanese Orthopaedic Association and visual analog scale scores improved significantly.

CONCLUSIONS

Endoscopic surgery for ACDF can produce satisfactory results in patients with cervical disc herniation, cervical myelopathy, or radiculopathy. The optimal levels for this procedure are C4-5 and C5-6. Compared with a traditional approach, this technique has great advantages in terms of cosmetic results, intraoperative visualization, and postoperative recovery course. Nevertheless, every precaution should be taken to avoid possible complications, such as postoperative hemorrhage.

Comparative anatomy of the porcine and human thoracic spines with reference to thoracoscopic surgical techniques

BACKGROUND

This study compared porcine and human thoracic spine anatomies for a better understanding of how structures encountered during thoracoscopy differ between training with a porcine model and actual surgery in humans.

METHODS

Parameters were measured including vertebral body height, width, and depth; disc height; rib spacing; spinal canal depth and width; and pedicle height and width.

RESULTS

Although most porcine vertebral structures were smaller, porcine pedicle height was significantly greater than that of humans because the porcine pedicle houses a unique transverse foramen. The longus colli and psoas attach, respectively, to T5 and T13 in swine and to T3 and T12 in humans. In swine, the azygos vein generally was absent. The intercostal veins drained into the hemiazygos vein.

CONCLUSIONS

Several thoracoscopically relevant anatomic differences between human and porcine spinal anatomies were identified. A thoracoscopic approach in a porcine model probably is best performed from the right side. The best general working area is between T6 and T10.

Endoscopic sentinel lymphadenectomy as a new diagnostic approach in the N0 neck

Sentinel lymphadenectomy was developed to reduce the extent of surgical interventions in cancer patients. The sentinel node (SN) concept was first established for melanoma and breast cancer; within some years, it also became increasingly popular for head and neck cancer. As soon as the required sensitivity of the method proves to be feasible in the daily clinical routine, the discussion about the best surgical approach to single or multiple SN(s) will arise. Different objectives may here compete with each other. The incision should render the best exposure of the operation site and should be expandable in case further lymph node regions have to be dissected. Finally, a good functional as well as a good cosmetic result is desirable. Endoscopic lymph node excisions were performed in patients suffering from squamous cell carcinoma of the upper aerodigestive tract located in different sites (1x uvula, 2x epiglottis, 1x glottis). In preoperatively performed ultrasonic imaging (B-mode-ultrasonography), N0 necks were assessed. In contrast to previously reported endoscopic techniques in humans, the presented method requires no insufflation of carbon dioxide or external retraction of the skin. Following laser surgical resection of the primary tumor, the SN and further lymph node(s) with accumulation of tracer substance were identified and resected endoscopically via an incision that was afterwards extended to a normal neck dissection incision. Reports of histopathologic examination of the sentinel node(s) were compared to the respective neck dissection specimens. The presented method may help to reduce the degree of invasiveness frequently attributed to sentinel lymphadenectomy once the method has been established for head and neck cancer.

Spinal fusion surgery: animal models for tissue-engineered bone constructs

Animal models have been used extensively to investigate the biology of fracture healing and spinal fusion. The goal of each spinal fusion model is to try and reproduce the correct sequence of events during osseous healing in humans. Animal models allow us the capability of dialing in fusion rates and fusion parameters depending upon the study conditions. These models have become invaluable in assessing the clinical potential of emerging technologies such as recombinant growth factors and gene therapy.

Percutaneous endoscopic cellular transplantation into the lower lumbar spinal cord

OBJECTIVE

To explore the feasibility of performing percutaneous endoscopic cellular transplantation into the lumbar spinal cord of pigs to create intramedullary cellular trails.

METHODS

The lumbar subarachnoid space was accessed using a 10-gauge needle inserted between L5 and L6. A 12.5-French flexible introducer sheath was fed over the needle into the subarachnoid space. A 3.2-mm-diameter flexible, steerable endoscope was then directed intradurally through the sheath. The thecal space was distended by saline infusion. A microcatheter with an attached needle then was advanced through the working channel into the dorsal surface of the lumbar spinal cord. Five microliters of Hoechst-labeled fibroblasts were injected while the catheter was withdrawn slowly to create a trail of cells within the spinal cord. The spinal canal then was perfused with fixative. The injected spinal cord segment was removed and studied histologically. Endoscopic video was analyzed offline.

RESULTS

The endoscope could be navigated under visual guidance. The sacral and lumbar rootlets, the spinal cord, and associated vessels were visualized. In fixed sagittal sections, a linear trail of fluorescent fibroblasts could be seen within the lumbar spinal cord in each specimen.

CONCLUSION

Percutaneous endoscopic cellular injection may be useful for cellular transplantation, may reduce surgical and anesthetic time, may be compatible with local anesthesia, may eliminate the need to disrupt spinal instrumentation and bone grafts, and may allow greater flexibility in the respective timing of spinal fixation and cellular transplantation after spinal cord injury. This is the first report of the use of endoscopic intraspinal cellular transplantation.