Faculty Bibliography

Background/UNASSIGNED:Prior to spine surgery (SS), we ask whether and when to stop low-dose aspirin (LD-ASA), particularly in patients with significant cardiovascular disease (CAD). Although platelets typically regenerate in 10 days, it can take longer in older patients. Methods/UNASSIGNED:Here we reviewed several studies regarding the perioperative risks/complications [e.g. hemorrhagic complications, estimated blood loss (EBL), continued postoperative drainage] for continuing vs. stopping LD-ASA at various intervals prior to lumbar SS. Results/UNASSIGNED:Multiple studies confirmed the increased perioperative risks for continuing LD-ASA throughout SS, or when stopping it for just 3-7 preoperative days; however, there were no increased risks if stopped between 7 to 10 days postoperatively. Other studies documented no increased perioperative risk for continuing LD-ASA throughout SS, although some indicated increased morbidity (e.g., one patient developed a postoperative hematoma resulting in irreversible paralysis). Conclusions/UNASSIGNED:Several studies demonstrated more hemorrhagic complications if LD-ASA was continued throughout or stopped just 3 to up to 7 days prior to SS. However, there were no adverse bleeding events if stopped from 7-10 days preoperatively. As a spine surgeon who wishes to avoid a postoperative epidural hematoma/paralysis, I would recommend stopping LD-ASA 10 days or longer prior to SS. Nevertheless, each spine surgeon must determine what is in the "best interest" of their individual patient. Certainly, we need future randomized controlled trials to better answer: when and if to stop LD-ASA before spine surgery.

Background/UNASSIGNED:The tethered cord syndrome (TCS) accompanying Chiari-1 (CM-1) malformations and the occult tethered cord syndrome (OTCS) syndrome accompanying the low lying cerebellar tonsil (LLCT) syndrome may be treated with sectioning of the filum terminale (SFT). Methods/UNASSIGNED:Utilizing PubMed, we reviewed the neurosurgical literature to determine how frequently spinal neurosurgeons diagnosed the TCS (e.g., conus terminating below the normal L1-L2 disc level) on lumbar magnetic resonance (MR) studies in patients with CM-1 malformations [e.g. tonsils >5-12 mm below the foramen magnum (FM) warranting SFT]. In addition, we assessed how frequently spinal neurosurgeons encountered the OTCS (e.g., conus normally located at L1-L2 on MR) accompanying the LLCT (e.g., tonsils herniated <5 mm below the FM) also requiring SFT. Results/UNASSIGNED:According to the neurosurgical literature, the incidence of TCS accompanying CM-1 requiring SFT ranged from 2.2% to < 6%, and up to 14%. Few studies additionally highly correlated the OCTS accompanying the LLCT syndrome warranting SFT. Conclusions/UNASSIGNED:Given the differences in the literature, more studies are needed to assess the risks (complications) vs. benefits (improved neurological outcomes) of SFT surgery for TCS with CM-1 and SFT for OCTS with LLCT.

Background/UNASSIGNED:Multiple measures prior to spine surgery may reduce the risks of postoperative surgical site infections (SSIs). Methods/UNASSIGNED:The incidence of SSI following spinal surgery (including reoperations and readmissions) may be markedly reduced by performing less extensive procedures and avoiding fusion where feasible. Preoperative testing up to 3 weeks postoperatively should include other studies to limit the perioperative SSI risk; cardiac stress tests (e.g., older patients/cardiac comorbidities), starting tamsulosin in males over 60 (e.g. avoid urinary retention due to benign prostatic hypertrophy), albumin/prealbumin levels (e.g., low levels increase SSI risk), and HBA1C levels to identify new/treat known diabetics (normalize/reduce preoperative levels). Results/UNASSIGNED:(patients/health-care workers), and bathing 2 weeks preoperatively with chlorhexidine gluconate 4% (not just night before/morning of surgery). Additionally, prior to surgery, the following medications that increase the bleeding risk should be stopped (e.g. for varying periods); anticoagulants, antiplatelet therapies (e.g., aspirin for at least 7-10 days), nonsteroidal anti-inflammatories (NSAIDS: timing depends on the drug), vitamin E, and herbal supplements. Additionally, avoiding elective spinal surgery in morbidly obese patients and recognizing other major medical contraindications to spinal surgery should help reduce infection, morbidity, and mortality rates. Conclusions/UNASSIGNED:Appropriate preoperative and intraoperative prophylactic maneuvers may reduce the risk of postoperative spinal SSI. Specific attention to these details may avoid infections and improve outcomes.

BACKGROUND: Many spine surgeons rely on reports of radiological studies for patients seen routinely in consultation. However, "best practice" should include the spine surgeon's individual assessment of the images themselves to better determine whether the diagnoses rendered were/are correct. METHODS: A now 54-year-old male had an original enhanced magnetic resonance imaging (MR) scan of the cervical spine performed in 2012 that was read as showing mild spondylotic changes at multiple levels. RESULTS: In 2015, the patient presented with a severe spastic quadriparesis, right greater than left, which had markedly worsened over the prior 3 months. Review of the original enhanced MR from 2012 revealed a right-sided C5-C6 tumor (e.g., likely meningioma) filling the right neural foramen with extension into the spinal canal (7 mm x 8 mm x 11 mm): The tumor was originally "missed". The new 2015 enhanced MR scan documented the tumor had enlarged 6.7 fold (measuring 17 mm x 11 mm x 2.2 cm), and now filled 2/3 of the spinal canal, markedly compressing the cord and right C6 nerve root. Following a C4-C6 laminectomy, and a challenging tumor removal, and the patient was neurologically intact. CONCLUSION: This case underscores the need for spine surgeons to carefully review both images and reports of prior diagnostic studies that accompany patients. In this case, the original failure to recognize the tumor led to a 2.5-year delay in surgery that resulted in the patient's severe preoperative quadriparesis, and a much more challenging surgery.

BACKGROUND:Few patients with neurodegenerative disorders (ND) (e.g., Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), and Postpolio Syndrome (PPS)) require spinal surgery. Typically, their neurological symptoms and signs reflect their underlying neurologic disorders rather than structural spinal pathology reported on magnetic resonance images (MR) or computed tomographic scans (CT). METHODS:The first author, a neurosurgeon, reviewed 437 spinal consultations performed over a 20-month period. Of 254 patients seen in first opinion (e.g., had not been seen by a spinal surgeon), 9 had MS, while 2 had ALS. Of 183 patients seen in second opinion (e.g., prior spinal surgeons recommended surgery), 4 had MS, 2 had ALS, and 1 had PPS. We performed this study to establish how often patients with ND, seen in first or second opinion, require spinal surgery. We focused on whether second opinions from spinal surgeons would limit the number of operations offered to these patients. RESULTS:Two of 11 patients with ND seen in first opinion required surgery. The first patient required a C5-7 laminectomy/C2-T2 fusion, followed by a L2-S1 laminectomy/L5S1 fusion. The second patient required a L2-L3 laminectomy/diskectomy/fusion. However, none of the seven patients seen in second opinion, who were previously told by outside surgeons they needed spinal surgery, required operations. CONCLUSIONS:Few patients with neurodegenerative syndromes (MS, ALS, PPS) and reported "significant" spondyloitic spinal disease interpreted on MR/CT studies required surgery. Great caution should be exercised in offering patients with ND spinal surgery, and second opinions should be encouraged to limit "unnecessary" procedures.

STUDY DESIGN/METHODS:The focus of this study was on the frequency of negative initial/subsequent ultrasound (US) of the lower extremities but positive spinal computed tomography contrast angiography (CTA) diagnostic of pulmonary embolism (PE) among 75 patients undergoing cervical laminectomy/fusion and 165 patients having lumbar laminectomy/noninstrumented fusion. OBJECTIVE:To determine the percentage/incidence of patients undergoing spinal surgery with negative US but with positive CTA. SUMMARY OF BACKGROUND DATA/BACKGROUND:The frequency of patients with negative US but with positive CTA after spinal surgery is not well documented. METHODS:For 240 spinal surgery patients, postoperative prophylaxis against deep venous thrombosis consisted of alternating pneumatic compression stockings alone. The patients were routinely screened on postoperative days 1 to 2 for deep venous thrombosis using US. The incidence of initial/subsequent negative US and positive CTA diagnostic for PE in patients with mild/major symptoms was evaluated, in conjunction with the frequency of hypercoagulation syndromes. RESULTS:Five (6.7%) patients undergoing cervical surgery and 6 patients (3.6%) undergoing lumbar surgery exhibited negative US but positive CTA on postoperative days 1 to 21. All the patients immediately received inferior vena cava filters (2 permanent and 9 retrievable). Five patients (45%) tested positive for hypercoagulation syndromes. Two patients were fully anticoagulated on postoperative days 3 and 21 with major symptoms attributed to saddle emboli; 1 had hypercoagulation syndrome. Anticoagulation was delayed for 6 to 12 weeks in 7 patients with milder symptoms, as magnetic resonance imaging scans showed residual seromas; 4 had hypercoagulation syndromes. Two elderly patients, at high risk for falls, without hypercoagulation syndromes were not anticoagulated. CONCLUSIONS:The frequency of negative US of the lower extremities but with positive CTA for PE after 240 cervical/lumbar spinal procedures in patients with mild/major symptoms ranged from 3.6% to 6.7%; 5 of the 11 patients exhibited hypercoagulation syndromes. To avoid failure to diagnose PE after spinal surgery, one should have a "low threshold" (eg, based even on minor symptoms) for requesting the CTA.

BACKGROUND CONTEXT: The immunogenicity of Gelfoam (Pharmacia and Upjohn, Kalamazoo, MI) or microfibrillar collagen, applied during laminectomy, may promote postoperative swelling and significant neural compression. PURPOSE: To document how Gelfoam contributes to marked cord/root compression on unenhanced/enhanced postoperative magnetic resonance (MR) scans. STUDY DESIGN/SETTING: This is a case report from the United States. PATIENT SAMPLE: A case report. OUTCOME MEASURE: The patient's neurological status was assessed using Nurick Grades. METHODS: A 73-year-old female with moderate myeloradiculopathy (Nurick Grade III) and MR/computed tomography (CT)-documented cord compression underwent a C6/C7 laminectomy (undercutting of C5-T1) with Gelfoam applied to the laminectomy site, followed by a C2-T2 fusion for instability (iliac autograft, Beta TriCalcium Phosphate). RESULTS: The patient improved for the first postoperative week (Nurick Grade 0-I), but deteriorated over the successive second and third postoperative weeks (Nurick Grade III). When the 3-week postoperative MR study documented marked dorsolateral cord compression at the laminectomy site, likely attributed to a postoperative seroma/hematoma, a second operation was performed. At surgery, no significant seroma/hematoma was found. Rather, markedly engorged Gelfoam densely adherent to and compressing the underlying dura was encountered; this was meticulously removed under the operating microscope using a small nerve hook. Postoperatively, the patient immediately improved. As the intraoperative culture revealed Acinetobacter baumannii, she required 6 weeks of intravenous Ertapenem (1-betamethyl-carbapenem). The MR scan performed on the third postoperative week revealed no residual cord compromise. CONCLUSIONS: Delayed postoperative deterioration in a 73-year-old female was attributed to reactive swelling/engorgement of Gelfoam at the C6-C7 laminectomy site.

STUDY DESIGN/METHODS:To determine whether the normovolemic hemodilution (NH) technique would limit postoperative homologous blood transfusion requirements in 68 patients having multilevel lumbar laminectomies (3-6 levels) with predominant 1- or 2-level instrumented fusions. OBJECTIVE:In this setting, to define postoperative homologous blood transfusion requirements using NH. SUMMARY OF BACKGROUND DATA/BACKGROUND:NH limits postoperative homologous blood transfusion requirements following various types of surgical procedures including those on the spine. METHODS:NH was used in an attempt to limit postoperative homologous transfusion requirements in 68 patients undergoing lumbar surgery. NH involves the removal of 1 to 2 U of blood replaced with crystalloid (2-4 mL per milliliter of blood harvested). Multiple variables contributing to homologous transfusion requirements were analyzed. RESULTS:Using NH, no homologous blood transfusions were required in 52 patients with a mean preoperative hematocrit of 41.3 undergoing average 3.7 level laminectomies with 1.5 level fusions. However, 16 patients with an average preoperative hematocrit of 38.5 undergoing average 4.3 level laminectomies with 1.6 level fusions required transfusion of 31 U of homologous blood after surgery. CONCLUSIONS:Using NH, 16 (23.5%) patients required 31 postoperative homologous blood transfusions. By contrast, the remaining 52 patients with similar procedures were able to avoid the use of homologous transfusion.

In the pediatric population, clear cell meningiomas are more frequently intracranial than intraspinal in location. Tumors recur in up to 40% of cases within 15 postoperative months and are often managed with repeated resection with or without radiation therapy. The management strategy for adults with clear cell meningiomas involving the lumbar spinal canal (cauda equina) is less clearly defined. A 41-year-old woman presented with mild, right greater than left, lower extremity paresis. An enhanced magnetic resonance (MR) scan revealed a homogeneously enhancing intradural lesion filling the spinal canal at the L3-L4 level. Preoperative noncontrast MR studies of the brain and cervical and thoracic spine were negative. An L2-L5 laminectomy was performed for gross total excision of the intradural lesion, which was adherent to one nerve root of the cauda equina. Frozen-section diagnosis confirmed clear cell tumor. Differential diagnoses included meningioma versus renal cell carcinoma. Negative postoperative chest, abdominal, and pelvic computed tomography studies ruled out tumor of renal cell origin. Enhanced MR studies of the neuraxis proved negative. Consultations with multiple oncologists and radiation therapists recommended neither radiation nor chemotherapy following this initial surgery. She remains disease-free 1 year postoperatively. The high recurrence rate for clear cell meningiomas in children requires repeated tumor resection with or without secondary radiation therapy. Following gross total resection of lumbar tumors in adults, reserving radiation therapy for secondary recurrences provides optimal management.

STUDY DESIGN: To determine the osteogenicity of posterior longitudinal ligament ossification, the posterior longitudinal ligament obtained during anterior cervical surgery from patients with the disorder was analyzed with in vitro cultures. OBJECTIVES: To determine the osteogenicity of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: The osteogenicity of posterior longitudinal ligament ossification in North America requires better documentation. METHODS: The posterior longitudinal ligament obtained during anterior cervical corpectomy with fusion from seven patients, three with ossification of the posterior longitudinal ligament documented by magnetic resonance imaging and computed tomography and four with spondylosis, was blindly submitted for in vitro culture. Explants of the posterior longitudinal ligament were placed in Dulbecco modified Eagle medium with 10% fetal calf serum, antibiotics, 4 mmol/L x L-proline, and 50 mg/L ascorbic acid. After reaching confluency, cells were trypsinized, and first-passage cells were used for all osteocalcin measurements to establish their osteoblastic phenotype. Periosteal cells, previously shown to synthesize osteocalcin, were used as a positive control. The cells were incubated with 1,25(OH)2 vitamin D3 at 10E-8 M for 72 hours in serum-free medium. The supernatants were collected and frozen, after which the quantity of osteocalcin induced by exposure to 1,25(OH)2 vitamin D3 was determined using enzyme-linked immunoassay. Control replicate cultures were measured without incubation using vitamin D3. RESULTS: Ossification of the posterior longitudinal ligament cell lines responded positively with osteocalcin synthesis in the 0.1 to 0.4 ng/M range. The cell line of the patient with spondylosis alone did not respond to vitamin D3 priming. CONCLUSIONS: Posterior longitudinal ligament cells from the three North American white patients with ossification of the posterior longitudinal ligament, when cultured in vitro, synthesized osteocalcin on vitamin D3 priming, confirming their osteoblastic phenotype, whereas posterior longitudinal ligament cells from four white patients with isolated spondylosis did not.