Faculty Bibliography

OBJECTIVE:To describe outcomes of awake transforaminal endoscopic surgical treatment for patients presenting with lumbar radiculopathy after laminectomy. METHODS:Awake endoscopic decompression surgery was performed on 538 patients over a 5-year period (2014-2019). Transforaminal endoscopic discectomy and foraminotomy was performed in 128 patients who had previously undergone laminectomy surgery. RESULTS:At 2-year follow-up, preoperative visual analog scale score for leg pain improved from 7.0 ± 1.4 to 2.0 ± 1.3 and Oswestry Disability Index score improved from 41.4% ± 11.9% to 12.4% ± 11.9% in 118 patients. During the 2-year follow-up period, 10 patients (7.8%) required repeat surgery at the treated level. CONCLUSIONS:The results of a minimally invasive awake endoscopic procedure are presented for the treatment of lumbar radiculopathy after lumbar laminectomy in a series of patients.

Chordoma is a low-grade notochordal tumor of the skull base, mobile spine and sacrum which behaves malignantly and confers a poor prognosis despite indolent growth patterns. These tumors often present late in the disease course, tend to encapsulate adjacent neurovascular anatomy, seed resection cavities, recur locally and respond poorly to radiotherapy and conventional chemotherapy, all of which make chordomas challenging to treat. Extent of surgical resection and adequacy of surgical margins are the most important prognostic factors and thus patients with chordoma should be cared for by a highly experienced, multi-disciplinary surgical team in a quaternary center. Ongoing research into the molecular pathophysiology of chordoma has led to the discovery of several pathways that may serve as potential targets for molecular therapy, including a multitude of receptor tyrosine kinases (e.g., platelet-derived growth factor receptor [PDGFR], epidermal growth factor receptor [EGFR]), downstream cascades (e.g., phosphoinositide 3-kinase [PI3K]/protein kinase B [Akt]/mechanistic target of rapamycin [mTOR]), brachyury-a transcription factor expressed ubiquitously in chordoma but not in other tissues-and the fibroblast growth factor [FGF]/mitogen-activated protein kinase kinase [MEK]/extracellular signal-regulated kinase [ERK] pathway. In this review article, the pathophysiology, diagnosis and modern treatment paradigms of chordoma will be discussed with an emphasis on the ongoing research and advances in the field that may lead to improved outcomes for patients with this challenging disease.

BACKGROUND:Conventional approaches to the thoracic spine can require extensive tissue dissection, bony disruption, and instability that may warrant the need for instrumentation and fusion. Furthermore, anterior approaches may require the involvement of various surgeons from multiple disciplines to ensure a successful operation and mitigate complications. Currently, available minimally invasive approaches still require bony removal and usually rely heavily on computed tomography (CT)-guided imaging without direct gross visualization. Endoscopic spinal procedures have provided an ultra-minimally invasive alternative to access many areas in and around the spinal column. METHODS:We present a 12-year-old boy with a right-sided 2.0 × 3.2-cm paravertebral lesion at the level of T5. The patient successfully underwent an endoscopic approach to the lesion with minimal tissue and bony disruption for tissue diagnosis and tumor resection. RESULTS:At initial and 6-month follow-up, the patient remained asymptomatic and without issues. CONCLUSIONS:We demonstrate here the feasibility and suggest the safety of a posterior ultra-minimally invasive endoscopic spinal approach to obtain a tissue biopsy of an incidentally found ventrolateral paraspinal tumor in the thoracic region in a pediatric patient. This minimal approach can prove to achieve similar results as other approaches that may otherwise necessitate more extensive or transthoracic procedures.

OBJECTIVE:Oncological outcomes for many malignant primary spinal tumors and isolated spinal metastases have been shown to correlate with extent of resection. For tumors with dural involvement, some authors have described spinal dural resection at the time of tumor resection in the interest of improving oncological outcomes. The complication profile associated with resection of the spinal dura for oncological purposes, however, and the relative influence of resecting tumor-involved dura on progression-free survival are not well defined. The authors performed a systematic review of the literature and identified cases in which the spinal dura was resected for oncological purposes in the interest of better understanding the associated risks and outcomes of this technique. METHODS:Electronic databases (PubMed/MEDLINE, Scopus) were systematically searched to identify studies that reported clinical and/or oncological outcomes of patients with malignant spinal neoplasms undergoing resection of tumor-involved dura at the time of surgical intervention. RESULTS:Ten articles describing 15 patients were included in the analysis. The most common tumor histologies were chordoma (3/15, 20%), giant cell tumor (3/15, 20%), epithelioid sarcoma (2/15, 13.3%), osteosarcoma (2/15, 13.3%), and metastasis (2/15, 13.3%). Procedure-related complications were reported in 40% of patients. A trend was seen toward an increased complication rate in redo (66.7%) versus index (16.7%) operations, but this trend did not reach statistical significance (p = 0.24). New, unexpected postoperative neurological deficits were seen in 3 patients (of 14 reporting, 21.4%). A single patient experienced a profound, unexpected neurological deterioration (paraparesis/paraplegia) after surgery, which reportedly improved considerably at latest follow-up. Tumor recurrence was seen in 3 cases (of 12 reporting, 25%) at a mean of 28.34 ± 21.1 months postoperatively. The overall mean radiographic follow-up period was 49.6 ± 36.5 months. CONCLUSIONS:Resection of the spinal dura for oncological purposes is rarely performed, although a limited number of reports and small series have demonstrated that it is feasible. Spinal dural resection is primarily performed in patients with isolated, primary spinal neoplasms with an intent to cure. The risk associated with spinal dura resection is nontrivial and the complication profile is significant. The influence of dural resection on oncological outcomes is not well defined, and further study is needed before definitive conclusions may be drawn regarding the oncological benefit of dural resection for any particular patient or pathology.

OBJECTIVE:While resection of the dural attachment has been shown by Simpson and others to reduce recurrence rates for intracranial meningiomas, the oncological benefit of dural resection for spinal meningiomas is less clear. The authors performed a systematic analysis of the literature, comparing recurrence rates for patients undergoing various Simpson grade resections of spinal meningiomas to better understand the role of dural resection on outcomes after resection of spinal meningiomas. METHODS:The PubMed/Medline database was systematically searched to identify studies describing oncological and clinical outcomes after Simpson grade I, II, III, or IV resections of spinal meningiomas. RESULTS:Thirty-two studies describing the outcomes of 896 patients were included in the analysis. Simpson grade I, grade II, and grade III/IV resections were performed in 27.5%, 64.6%, and 7.9% of cases, respectively. The risk of procedure-related complications (OR 4.75, 95% CI 1.27-17.8, p = 0.021) and new, unexpected postoperative neurological deficits (OR ∞, 95% CI NaN-∞, p = 0.009) were both significantly greater for patients undergoing Simpson grade I resections when compared with those undergoing Simpson grade II resections. Tumor recurrence was seen in 2.8%, 4.1%, and 39.4% of patients undergoing Simpson grade I, grade II, and grade III/IV resections over a mean radiographic follow-up period of 99.3 ± 46.4 months, 95.4 ± 57.1 months, and 82.4 ± 49.3 months, respectively. No significant difference was detected between the recurrence rates for Simpson grade I versus Simpson grade II resections (OR 1.43, 95% CI 0.61-3.39, p = 0.43). A meta-analysis of 7 studies directly comparing recurrence rates for Simpson grade I and II resections demonstrated a trend toward a decreased likelihood of recurrence after Simpson grade I resection when compared with Simpson grade II resection, although this trend did not reach statistical significance (OR 0.56, 95% CI 0.23-1.36, p = 0.20). CONCLUSIONS:The results of this analysis suggest with a low level of confidence that the rates of complications and new, unexpected neurological deficits after Simpson grade I resection of spinal meningiomas are greater than those seen with Simpson grade II resections, and that the recurrence rates for Simpson grade I and grade II resections are equivalent, although additional, long-term studies are needed before reliable conclusions may be drawn.

OBJECTIVE:Lumbar facet cysts are commonly seen in degenerative lumbar conditions causing stenosis and radiculopathy. Extraforaminal lumbar facet cysts are a rare entity and present a surgical challenge because of their location. Transforaminal endoscopic spine surgery is an emerging technique in spine surgery but has never been described as a treatment option for lumbar radiculopathy in the setting of extraforaminal lumbar facet cyst. METHODS:A technique for the transforaminal endoscopic treatment of an extraforaminal lumbar facet cyst is presented in 2 patients. We retrospectively reviewed 321 cases of patients who underwent transforaminal endoscopic surgery in a 4-year period with a minimum follow-up of 2 years. RESULTS:A series of 2 patients who underwent transforaminal endoscopic foraminotomy and cyst resection procedures for extraforaminal lumbar facet cysts between 2014 and 2017 is presented: A 51-year-old woman with a right L4-5 extraforaminal cyst improved from a preoperative visual analog scale (VAS) of 7 and Oswestry disability index (ODI) of 26 to a 1-year postoperative VAS score of 2 and ODI of 4; and a 71-year-old woman with a left L5-S1 extraforaminal cyst improved from a preoperative VAS of 7 and ODI of 30 to a 1-year postoperative VAS score of 2 and ODI of 6. CONCLUSIONS:Transforaminal endoscopic surgery for a lumbar radiculopathy in the setting of an extraforaminal lumbar facet cyst is presented as a unique minimally invasive approach for the treatment of extraforaminal lumbar facet cyst that avoids facet resection and fusion.

OBJECTIVE:To evaluate the incidence and outcomes of incidental durotomy in transforaminal endoscopic spine surgery. METHODS:Transforaminal lumbar endoscopic procedures were performed by 2 surgeons in 907 patients over a period of 4 years from 2014 to 2018. Patient data were evaluated retrospectively in these patients with a minimum follow-up of 1 year. RESULTS:In 907 patients over 4 years there were 5 durotomies: 4 incidental and 1 intentional. The rate for incidental durotomy was therefore 0.4%. There were no adverse outcomes from the incidental durotomies, and only 1 patient noted a headache. CONCLUSIONS:Incidental durotomy is a rare complication of transforaminal lumbar endoscopic spine surgery and appears to occur more likely in patients who have undergone previous spine surgery at the site of the endoscopic procedure, not unexpectantly. Glues, patches, and bedrest were among the various methods used after durotomy. In this series there were no cases of symptomatic spinal fluid leakage or pseudomeningocele seen. Only 20% of patients who had durotomies noted a headache in the immediate postoperative period.

OBJECTIVE:Assessment of transverse ligament (TL) competence in patients with suspected atlantoaxial instability is performed via indirect radiograph measurements or direct TL visualization on magnetic resonance imaging (MRI). Interpretation of these images can be limited by unique patient anatomy or imaging technique variability. We report a novel technique for evaluating TL competence using flexion-extension computed tomography (feCT) scan with 3-dimensional (3D) segmentation and quantitative analysis. METHODS:feCT scans of 11 patients were segmented to create 3D surface models. Six patients with atlantoaxial pathology were evaluated for possible instability based on clinical examination and imaging findings. The other 5 patients had no clinical or imaging evidence of atlantoaxial injury. Dynamic atlantodental interval (ADI) was calculated using point-to-point voxel changes between flexion and extension 3D models. Magnitude and direction of ADI changes were quantified and compared with available cervical spine flexion-extension radiograph and/or MRI findings. RESULTS:In the 5 patients without evidence of atlantoaxial injury, 94.3% of ADI vector changes were <3.0 mm. In the 3 patients with atlantoaxial pathology but TL competence, 92.4% of ADI vector changes were <3.0 mm. In the 3 patients with atlantoaxial pathology and TL incompetence, only 49.1% of ADI vector changes were <3.0 mm. In addition to the significant atlantoaxial subluxation in these 3 patients, there was significant rotational motion compared with the patients with an intact TL. CONCLUSIONS:3D segmentation and quantitative analysis of feCT scan allow objective indirect assessment of TL integrity. Results are consistent with MRI findings and offer additional biomechanical information regarding the direction and distribution of atlantoaxial motion.

OBJECTIVE:We sought to evaluate the feasibility for awake, endoscopic treatment of lumbar pseudarthrosis after a transforaminal lumbar interbody fusion (TLIF). METHODS:A 71-year-old male with severe cardiac disease, determined to be high risk for general anesthesia, presented with mechanical back pain and a L3-4 pseudarthrosis and L3 pedicle screw loosening after a L3-5 TLIF. An awake, transforaminal endoscopic redo diskectomy and TLIF procedure were performed by removing residual disk material adjacent to the previous "PEEK" (polyetheretherketone) interbody spacer and placing allograft, bone morphogenetic protein, and an expandable titanium interbody device adjacent to the PEEK cage. RESULTS:At 1-year follow-up, preoperative visual analog scale for back pain and Oswestry disability index improved from 7 and 38% to 1 and 2%. The 1-year follow-up radiograph showed stable interbody placement and no further screw loosening. CONCLUSIONS:A minimally invasive, awake procedure is presented for the treatment of pseudarthrosis after TLIF.

Recent literature suggests that adult patients with spina bifida receive surgery for degenerative disc disease at higher rates than the general population. However, sometimes the complex anatomic features of co-occurring spina bifida and lumbar disc herniation can significantly challenge standard surgical techniques. Here, the technical steps are presented for treating a foraminal lumbar 4-5-disc herniation in the setting of a patient with multifaceted degenerative and spina bifida occulta anatomy. Utilized is a minimally invasive approach that does not require general anesthesia or fusion and allows the patient to leave the same day. To the best of our knowledge, this is the first-reported case of endoscopic surgical decompression of a lumbar disc in a patient with spina bifida.