Gout in the thoracic spine causing acute paraplegia: illustrative case.

BACKGROUND: Although spinal involvement by gout is not uncommon, spinal gout leading to symptomatic spinal cord compression in the thoracic spine is very rare and poses a diagnostic challenge by mimicking symptoms of more common diagnoses such as epidural abscess and malignancy. An even more unique presentation is spinal gout causing thoracic cord compression leading to acute paraplegia. OBSERVATIONS: The authors present an illustrative case of a 35-year-old man with thoracic spinal compression by tophaceous gout who developed rapid progression to complete paraplegia over a 5-day period. Magnetic resonance imaging of the thoracic spine revealed a cystic-appearing lesion within the dorsal extradural space of the lower thoracic spine extending from T8 to T10 accompanied by compression of the spinal cord. An emergent T9-10 laminectomy was performed, and the occupying lesion in the thoracic spine was resected. The diagnosis of spinal tophaceous gout was made by pathological examination. LESSONS: Although varying clinical manifestations of spinal gout have been reported in the literature, the patient's age and the rapid progression to complete paraplegia over a 5-day period reveals a unique presentation that broadens understanding of the manner in which this condition can present and allow more rapid diagnosis and treatment.

Intraoperative cone beam-computed tomography with navigation (O-ARM) versus conventional fluoroscopy (C-ARM): a cadaveric study comparing accuracy, efficiency, and safety for spinal instrumentation.

STUDY DESIGN: Cadaveric laboratory study. OBJECTIVE: To compare the accuracy, efficiency, and safety of intraoperative cone beam-computed tomography with navigation (O-ARM) with traditional intraoperative fluoroscopy (C-ARM) for the placement of pedicle screws. SUMMARY OF BACKGROUND DATA: Radiation exposure remains a concern with traditional methods of intraoperative imaging in spine surgery. The use of O-ARM has been proposed for more accurate and efficient spinal instrumentation. Understanding radiation imparted to patients and surgeons by O-ARM is important for assessing risks and benefits of this technology, especially in light of evolving indications. METHODS: Four surgeons placed 160 pedicle screws on 8 cadavers without deformity. Eighty pedicle screws were placed using O-ARM and C-ARM each. Instrumentation was placed bilaterally in the thoracic (T1-T6) spine and lumbosacral junction (L5-S1) using a standard open technique, whereas minimally invasive surgery technique was used at the lumbar 3 to 4 (L3-L4) level. A "postoperative" computed tomography (CT) scan was performed on cadavers where instrumentation was done using the C-ARM. An independent musculoskeletal radiologist assessed final images for screw position. Time required to set up and instrumentation was recorded. Dosimeters were placed on multiple aspects of cadavers and surgeons to record radiation exposure. RESULTS: There were no differences in breach rate between the O-ARM and C-ARM groups (5 vs. 7, χ= 0.63, P = 0.4). The setup time for the O-ARM group was longer than that for the C-ARM group (592 vs. 297 s, P < 0.05). However, the average total time was statistically the same (1629 vs. 1639 s, P = 0.96). Radiation exposure was higher for surgeons in the C-ARM group and cadavers in the O-ARM group. When a "postoperative" CT scan was included in the estimation of the total radiation exposure, there was less of difference between the groups, but still more for the O-ARM group. CONCLUSION: In cadavers without deformity, O-ARM use results in similar breach rates as C-ARM for the placement of pedicle screws. Time for instrumentation is shorter with the O-ARM, but requires a longer setup time. The O-ARM exposes less radiation to the surgeon, but higher doses to the cadaver. LEVEL OF EVIDENCE: N/A.

Spinal fibromatosis: a report of two cases and review of the literature.

BACKGROUND CONTEXT: Spinal fibromatosis is a unique subset of fibromatosis that is only anecdotally described in the literature in sporadic case reports. According to our review of the literature, only 11 cases of spinal fibromatosis have been previously documented. This paucity of clinical data limits our understanding of its presentation and treatment. PURPOSE: The authors present the first two cases of spinal fibromatosis encountered at their institution, and review the literature of reported cases to elucidate the presentation and outcomes of patients with this rare tumor. STUDY DESIGN: A report of two cases and review of the literature. METHODS: The two patients in our case report were women aged 45 and 38 years. Both of the patients presented to our clinic after previous excisional biopsy of a spinal mass, 17 years and 1 year later, respectively, with pain and paresthesias that recapitulated their former symptoms. Thirteen cases, including the two described in the current article, were culled from the literature. RESULTS: Magnetic resonance imaging revealed an enhancing lesion in the posterior elements of the spinal column in the first case and a paraspinal soft tissue mass in the second case. The tumors were histologically defined by haphazardly arranged, elongated, and slender spindle cells separated by abundant collagen without mitoses or necrosis. Surgical management resulted in intralesional resection in the first case and en bloc resection in the second case. By 40 and 10 months after surgery, both patients remain without neurologic deficits. CONCLUSIONS: Among 13 cases of spinal fibromatosis, pain with or without a mass is the most common symptom at presentation. Tumor etiology is evenly distributed between de novo origin and surgical trauma. Treatment outcomes, although, cannot be determined from the limited data currently available.

Overcoming challenges associated with upright imaging of the cervicothoracic junction: a case report involving a novel repurposing of the O-arm.

BACKGROUND: Prior to the mobilization of patients with spinal fractures following treatment, it is important to confirm stability in the upright position. METHODS: A patient presented with T2 and T3 vertebral body fractures visible on recumbent CT. Supine and upright plain x-rays with additional swimmer's views were deemed suboptimal prior to mobilization. The default configuration of the O-arm was modified to enable imaging in the upright position. RESULTS: Images utilizing the O-arm were satisfactory and anatomic alignment confirmed in an upright position. It is believed that this is the first time the O-arm has been used for upright diagnostic imaging (off-label application). Excellent visualization of the cervicothoracic junction and upper thoracic regions was obtained in the desired upright position. CONCLUSION: The O-arm was used successfully to image spinal trauma in the upright position and may represent a new application of the device, potentially fulfilling a frequently unmet medical imaging need.

Biomechanics of a lumbar interspinous anchor with transforaminal lumbar interbody fixation.

OBJECT: To study the stability offered by a clamping lumbar interspinous anchor (ISA) for transforaminal lumbar interbody fusion (TLIF). METHODS: Seven human cadaveric lumbosacral specimens were tested: 1) intact; 2) after placing ISA; 3) after TLIF with ISA; 4) with TLIF, ISA, and unilateral pedicle screws-rod; 5) with TLIF and unilateral pedicle screws-rod (ISA removed); and 6) with TLIF and bilateral pedicle screws-rods. Pure moments (7.5 Nm maximum) were applied in each plane to induce flexion-extension, axial rotation, and lateral bending while recording angular motion optoelectronically. Compression (400 N) was applied while upright foraminal height was measured. RESULTS: All instrumentation reduced angular range of motion (ROM) significantly from normal. The loading modes in which the ISA limited ROM most effectively were flexion and extension, where the ROM allowed was equivalent to that of pedicle screws-rods (P > .08). The ISA was least effective in reducing lateral bending, with this mode reduced to 81% of normal. TLIF with unilateral pedicle screws-rod was the least stable configuration. Addition of the ISA to this construct significantly improved stability during flexion, extension, lateral bending, and axial rotation (P < .008). Constructs that included the ISA increased the foraminal height an average of 0.7 mm more than the other constructs (P < .05). CONCLUSIONS: In cadaveric testing, the ISA limits flexion and extension equivalently to pedicle screws-rods. It also increases foraminal height. When used with TLIF, a construct of ISA or ISA plus unilateral pedicle screws-rod may offer an alternative to bilateral pedicle screws-rods for supplemental posterior fixation.

Biomechanics of a lumbar interspinous anchor with anterior lumbar interbody fusion.

OBJECT: An interspinous anchor (ISA) provides fixation to the lumbar spine to facilitate fusion. The biomechanical stability provided by the Aspen ISA was studied in applications utilizing an anterior lumbar interbody fusion (ALIF) construct. METHODS: Seven human cadaveric L3-S1 specimens were tested in the following states: 1) intact; 2) after placing an ISA at L4-5; 3) after ALIF with an ISA; 4) after ALIF with an ISA and anterior screw/plate fixation system; 5) after removing the ISA (ALIF with plate only); 6) after removing the plate (ALIF only); and 7) after applying bilateral pedicle screws and rods. Pure moments (7.5 Nm maximum) were applied in flexion and extension, lateral bending, and axial rotation while recording angular motion optoelectronically. Changes in angulation as well as foraminal height were also measured. RESULTS: All instrumentation variances except ALIF alone reduced angular range of motion (ROM) significantly from normal in all directions of loading. The ISA was most effective in limiting flexion and extension (25% of normal) and less effective in reducing lateral bending (71% of normal) and axial rotation (71% of normal). Overall, ALIF with an ISA provided stability that was statistically equivalent to ALIF with bilateral pedicle screws and rods. An ISA-augmented ALIF allowed less ROM than plate-augmented ALIF during flexion, extension, and lateral bending. Use of the ISA resulted in flexion at the index level, with a resultant increase in foraminal height. Compensatory extension at the adjacent levels prevented any significant change in overall sagittal balance. CONCLUSIONS: When used with ALIF at L4-5, the ISA provides immediate rigid immobilization of the lumbar spine, allowing equivalent ROM to that of a pedicle screw/rod system, and smaller ROM than an anterior plate. When used with ALIF, the ISA may offer an alternative to anterior plate fixation or bilateral pedicle screw/rod constructs.

A comparison of two techniques in image-guided thoracic pedicle screw placement: a retrospective study of 37 patients and 277 pedicle screws.

OBJECT: The goal of this study was to compare the accuracy of thoracic pedicle screw placement aided by two different image-guidance modalities. METHODS: The charts of 40 consecutive patients who had undergone stabilization of the thoracic spine between January 2003 and January 2005 were retrospectively reviewed. Three patients were excluded from the study because, on the basis of preoperative findings, small pedicle diameter precluded the use of pedicle screws. Thus, a total of 37 patients had 277 screws placed with the aid of either virtual fluoroscopy or isocentric C-arm 3D navigation. The indications for surgery included trauma, degenerative disease, and tumor, and were similar in both groups. All 37 patients underwent postoperative computed tomography scanning, and an independent reviewer graded all screws based on axial, sagittal, and coronal projections for a full determination of the placement of the screw in the pedicle. RESULTS: The rate of unintended perforations was found to depend on pedicle diameter (p < 0.0001). There were no statistical differences between groups with regard to rate or grade of cortical perforations. Overall, the rate and grade of perforations was low, and there were no neurological or vascular complications. CONCLUSIONS: The authors have shown that either image-guidance system may be used with a high degree of accuracy and safety. Because both systems were found to be comparably safe and accurate, the choice of image-guidance modality may be determined by the level of surgeon comfort and/or availability of the system.