Faculty Bibliography

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.

STUDY DESIGN: To establish the diagnosis of dural penetration on preoperative computed tomographic studies of the cervical spine in patients with ossification of the posterior longitudinal ligament (OPLL). OBJECTIVES: To define before surgery the pathognomonic computed tomographic findings of OPLL extending to and through the dura. SUMMARY OF BACKGROUND DATA: On preoperative computed tomographic studies, Hida et al have described the single-layer sign characterized by a solid mass of hyperdense OPLL and the double-layer sign defined by two (anterior and posterior) ossified rims surrounding a central nonossified but hypertrophied posterior longitudinal ligament. Only 1 of the 9 patients exhibiting the single-layer sign but 10 of 12 patients showing the double-layer sign had no separate dural plane identified at surgery. METHODS: Only 2 of 54 patients undergoing multilevel cervical circumferential OPLL procedures had absent dura at surgery. Computed tomographic examinations for all patients were retrospectively reviewed to determine unique signs of dural penetration. RESULTS: Dura was absent in 1 of 12 patients who had the single-layer CT sign that was additionally characterized by an irregular C angular configuration. Only 1 of 4 patients exhibiting the double-layer computed tomographic sign had absent dura at surgery. The remaining 38 patients had the smooth-layer sign, characterized by more regular margins of classic (22 patients) or early OPLL (16 patients). CONCLUSIONS: The double-layer computed tomographic sign is more pathognomonic for dural penetration than the single-layer sign. The smooth-layer sign, indicating a clean dural plane, is more typical in North American patients

Cervical laminectomy with posterior wiring and fusion is valuable for the management of cervical ossification of the posterior longitudinal ligament (OPLL), spondylosis, ossification of the yellow ligament (OYL), stenosis, and instability. Within 1.5 years, five patients averaging 73 years of age developed severe myelopathy. Dynamic radiographs confirmed an intact cervical lordosis with active subluxation and instability at one or two levels, whereas magnetic resonance and computed tomography scans showed OPLL, spondylosis, OYL, and stenosis. After multilevel laminectomy with posterior wiring and fusion and immobilization in cervicothoracic orthoses, patients fused in an average of 3.6 months. All patients improved, showing mild to moderate residual postoperative myelopathy an average of 13 months later (range, 6-19 months). With an intact cervical lordosis, laminectomy with posterior wiring and fusion was used successfully to manage five patients with OPLL, spondylosis, OYL, stenosis, and instability

The authors evaluated the clinical, radiological, and surgical management of ossification of the anterior longitudinal ligament (OALL) that contributed to dysphagia in a patient with simultaneous cervical ossification of the posterior longitudinal ligament (OPLL). A 57-year-old man presented with increasing dysphagia and moderate myelopathy. Imaging studies, including esophagoscopy, revealed marked esophageal compression due to OALL that extended between the C2-5 levels and significant C5-7 OPLL that compressed the distal cervical spinal cord. The use of rongeurs and a high-speed drill facilitated excision of the C2-5 OALL mass, and a routine anterior corpectomy with fusion was performed at the C5-7 level. Postoperatively, the patient's dysphagia and symptoms of myelopathy immediately resolved. The strut graft became fully fused 3 months postoperatively, as demonstrated on dynamic x-ray films, and the patient has remained asymptomatic 4 months postoperatively. Patients with dysphagia and coexisting myelopathy benefit from simultaneous surgery for resection of OALL and OPLL masses

Can simultaneous anterior and posterior (circumferential) surgery in patients with cervical ossification of the posterior longitudinal ligament (OPLL)/stenosis, achieving both decompression and stabilization, be accomplished with acceptable risk? Between 1989 and 1996, 22 circumferential procedures were performed, including an average 2.5-level anterior corpectomy with 5-level posterior wiring and fusion. These patients were severely myelopathic (average Nurick grade 3.5) and were followed for a mean interval of 22 months (range 4-52 months). Circumferential procedures required an average of 9.8 h and 3.5 U of blood transfused. Postoperatively, patients improved approximately +3.0 Nurick grades. Simultaneous circumferential surgery for OPLL/stenosis may be successfully performed in <10 h with limited blood loss.

In the cervical spine, routine and contrast magnetic resonance (MR)- and computed tomography (CT)-based studies may fail to differentiate between an ectatic vertebral artery and a solid foraminal mass. A complete cervical and lumbar Myelo-CT scan in a 67-year-old female with lumbar stenosis revealed an incidental, left-sided C3-C4 foraminal mass. A vascular lesion was suspected when the MR study revealed the lesion to be a signal void. MR angiography confirmed an ectatic C3-C4 vertebral artery loop. The possibility of a vertebral artery anomaly should be considered in patients with asymptomatic lateral and foraminal cervical lesions on CT studies. In these patients, routine MR and MR angiography are necessary to demonstrate the status of the vertebral artery in the foramen.