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James Feghali, Risheng Xu, Wuyang Yang, Jason Anthony Liew, Jaishri Blakeley, Edward S. Ahn, Rafael J. Tamargo and Judy Huang

OBJECTIVE

Phenotypic differences between moyamoya disease (MMD) and moyamoya syndrome (MMS) remain unclear. The purpose of this study was to evaluate whether such differences exist when presentation, procedure-related, and outcome variables are compared quantitatively.

METHODS

The study cohort included 185 patients with moyamoya presenting to the Johns Hopkins Medical Institutions between 1994 and 2015. Baseline demographic, angiographic, and clinical characteristics were compared between patients with MMS and MMD, in addition to procedure-related complications and length of stay (LOS) after surgery. Stroke-free survival was compared between both disease variants after diagnosis. Kaplan-Meier analysis and Cox proportional hazards regression were used to compare stroke-free survival between surgically treated and conservatively managed hemispheres in both types of disease, while evaluating interaction between disease variant and management.

RESULTS

The cohort consisted of 137 patients with MMD (74%) with a bimodal age distribution and 48 patients with MMS (26%) who were mostly under 18 years of age (75%). Underlying diseases included sickle cell disease (48%), trisomy 21 (12%), neurofibromatosis (23%), and other disorders (17%). Patients with MMS were younger (p < 0.001) and less likely to be female (p = 0.034). Otherwise, baseline characteristics were statistically comparable. The rate of surgical complications was 33% in patients with MMD and 16% in patients with MMS (p = 0.097). Both groups of patients had a similar LOS after surgery (p = 0.823). Survival analysis (n = 330 hemispheres) showed similar stroke-free survival after diagnosis (p = 0.856) and lower stroke hazard in surgically managed patients in both MMD (hazard ratio [HR] 0.29, p = 0.028) and MMS (HR 0.62, p = 0.586). The disease variant (MMD vs MMS) did not affect the relationship between management approach (surgery vs conservative) and stroke hazard (p = 0.787).

CONCLUSIONS

MMD and MMS have largely comparable clinical and angiographic phenotypes with analogously favorable responses to surgical revascularization.

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Risheng Xu, Matthew J. McGirt, Edward G. Sutter, Daniel M. Sciubba, Jean-Paul Wolinsky, Timothy F. Witham, Ziya L. Gokaslan and Ali Bydon

Object

The aim of this study was to conduct the first in vitro biomechanical comparison of immediate and postcyclical rigidities of C-7 lateral mass versus C-7 pedicle screws in posterior C4–7 constructs.

Methods

Ten human cadaveric spines were treated with C4–6 lateral mass screw and C-7 lateral mass (5 specimens) versus pedicle (5 specimens) screw fixation. Spines were potted in polymethylmethacrylate bone cement and placed on a materials testing machine. Rotation about the axis of bending was measured using passive retroreflective markers and infrared motion capture cameras. The motion of C-4 relative to C-7 in flexion-extension and lateral bending was assessed uninstrumented, immediately after instrumentation, and following 40,000 cycles of 4 Nm of flexion-extension and lateral bending moments at 1 Hz. The effect of instrumentation and cyclical loading on rotational motion across C4–7 was analyzed for significance.

Results

Preinstrumented spines for the 2 cohorts were comparable in bone mineral density and range of motion in both flexion-extension (p = 0.33) and lateral bending (p = 0.16). Lateral mass and pedicle screw constructs significantly reduced motion during flexion-extension (11.3°–0.26° for lateral mass screws, p = 0.002; 10.51°–0.30° for pedicle screws, p = 0.008) and lateral bending (7.38°–0.27° for lateral mass screws, p = 0.003; 11.65°–0.49° for pedicle screws, p = 0.03). After cyclical loading in both cohorts, rotational motion over C4–7 was increased during flexion-extension (0.26°–0.68° for lateral mass screws; 0.30°–1.31° for pedicle screws) and lateral bending (0.27°–0.39° and 0.49°–0.80°, respectively), although the increase was not statistically significant (p > 0.05). There was no statistical difference in postcyclical flexion-extension (p = 0.20) and lateral bending (0.10) between lateral mass and pedicle screws.

Conclusions

Both C-7 lateral mass and C-7 pedicle screws allow equally rigid fixation of subaxial lateral mass constructs ending at C-7. Immediately and within a simulated 6-week postfixation period, C-7 lateral mass screws may be as effective as C-7 pedicle screws in biomechanically stabilizing long subaxial lateral mass constructs.

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Wuyang Yang, Risheng Xu, Jose L. Porras, Clifford M. Takemoto, Syed Khalid, Tomas Garzon-Muvdi, Justin M. Caplan, Geoffrey P. Colby, Alexander L. Coon, Rafael J. Tamargo, Judy Huang and Edward S. Ahn

OBJECTIVE

Sickle cell disease (SCD) in combination with moyamoya syndrome (MMS) represents a rare complication of SCD, with potentially devastating neurological outcomes. The effectiveness of surgical revascularization in this patient population is currently unclear. The authors’ aim was to determine the effectiveness of surgical intervention in their series of SCD-MMS patients by comparing stroke recurrence in those undergoing revascularization and those undergoing conservative transfusion therapy.

METHODS

The authors performed a retrospective chart review of patients with MMS who were seen at the Johns Hopkins Medical Institution between 1990 and 2013. Pediatric patients (age < 18 years) with confirmed diagnoses of SCD and MMS were included. Intracranial stroke occurrence during the follow-up period was compared between surgically and conservatively managed patients.

RESULTS

A total of 15 pediatric SCD-MMS patients (28 affected hemispheres) were included in this study, and all were African American. Seven patients (12 hemispheres) were treated with indirect surgical revascularization. The average age at MMS diagnosis was 9.0 ± 4.0 years, and 9 patients (60.0%) were female. Fourteen patients (93.3%) had strokes before diagnosis of MMS, with an average age at first stroke of 6.6 ± 3.9 years. During an average follow-up period of 11.6 years, 4 patients in the conservative treatment group experienced strokes in 5 hemispheres, whereas no patient undergoing the revascularization procedure had any strokes at follow-up (p = 0.029). Three patients experienced immediate postoperative transient ischemic attacks, but all recovered without subsequent strokes.

CONCLUSIONS

Indirect revascularization is suggested as a safe and effective alternative to the best medical therapy alone in patients with SCD-MMS. High-risk patients managed on a regimen of chronic transfusion should be considered for indirect revascularization to maximize the effect of stroke prevention.

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Saksham Gupta, Blake M. Hauser, Mark M. Zaki, Edward Xu, David J. Cote, Yi Lu, John H. Chi, Michael Groff, Ayaz M. Khawaja, Mitchel B. Harris, Timothy R. Smith and Hasan A. Zaidi

OBJECTIVE

Sports injuries present a considerable risk of debilitating spinal injury. Here, the authors sought to profile the epidemiology and clinical risk of traumatic spinal injuries (TSIs) in pediatric sports injuries.

METHODS

The authors conducted a retrospective cohort analysis of pediatric patients who had experienced a sports-related TSI, including spinal fractures and spinal cord injuries, encoded in the National Trauma Data Bank in the period from 2011 to 2014.

RESULTS

Included in the analysis were 1723 cases of pediatric sports-related TSI, which represented 3.7% of all pediatric sports-related trauma. The majority of patients with TSI were male (81%), and the median age was 15 years (IQR 13–16 years). TSIs arose most often from cycling accidents (47%) and contact sports (28%). The most frequently fractured regions were the thoracic (30%) and cervical (27%) spine. Among patients with spinal cord involvement (SCI), the cervical spine was involved in 60% of cases.

The average length of stay for TSIs was 2 days (IQR 1–5 days), and 32% of the patients required ICU-level care. Relative to other sports-related trauma, TSIs without SCI were associated with an increased adjusted mean length of stay by 1.8 days (95% CI 1.6–2.0 days), as well as the need for ICU-level care (adjusted odds ratio [aOR] 1.6, 95% CI 1.3–1.9). Also relative to other sports-related trauma, TSIs with SCI had an increased length of stay by 2.1 days (95% CI 1.8–2.6 days) and the need for ICU-level care (aOR 3.6, 95% CI 2.6–4.8).

TSIs without SCI were associated with discharge to or with rehabilitative services (aOR 1.7, 95% CI 1.5–2.0), as were TSIs with SCI (aOR 4.0, 95% CI 3.2–4.9), both relative to other sports-related trauma. Among the patients with TSIs, predictors of the need for rehabilitation at discharge were having a laminectomy or fusion, concomitant lower-extremity injury, head injury, and thoracic injury. Although TSIs affected 4% of the study cohort, these injuries were present in 8% of patients discharged to or with rehabilitation services and in 17% of those who died in the hospital.

CONCLUSIONS

Traumatic sports-related spinal injuries cause significant morbidity in the pediatric population, especially if the spinal cord is involved. The majority of TSI cases arose from cycling and contact sports accidents, underscoring the need for improving education and safety in these activities.

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Colin J. Przybylowski, Robert F. Dallapiazza, Brian J. Williams, I. Jonathan Pomeraniec, Zhiyuan Xu, Spencer C. Payne, Edward R. Laws and John A. Jane Jr.

OBJECTIVE

The object of this study was to compare the outcomes of primary and revision transsphenoidal resection (TSR) of nonfunctioning pituitary macroadenomas (NFPMAs) using endoscopic methods.

METHODS

The authors retrospectively reviewed the records of 287 consecutive patients who had undergone endoscopic endonasal TSR for NFPMAs at their institution in the period from 2005 to 2011. Fifty patients who had undergone revision TSR were retrospectively matched for age, sex, and duration of follow-up to 46 patients who had undergone primary TSR. Medical and surgical complications were documented, and Kaplan-Meier analysis was performed to assess rates of radiological progression-free survival (PFS).

RESULTS

The median follow-up periods were 45 and 46 months for the primary and revision TSR groups, respectively. There were no significant differences between the primary and revision groups in rates of new neurological deficit (0 in each), vascular injury (2% vs 0), postoperative CSF leak (6% vs 2%), transient diabetes insipidus (DI; 15% vs 12%), chronic DI (2% vs 2%), chronic sinusitis (4% vs 6%), meningitis (2% vs 2%), epistaxis (7% vs 0), or suprasellar hematoma formation (0 vs 2%). However, patients who underwent primary TSR had significantly higher rates of syndrome of inappropriate antidiuretic hormone (SIADH; 17% vs 4%, p = 0.04). Patients who underwent primary operations also had significantly higher rates of gross-total resection (GTR; 63% vs 28%, p < 0.01) and significantly lower rates of adjuvant radiotherapy (13% vs 42%, p < 0.01). Radiological PFS rates were similar at 2 years (98% vs 96%) and 5 years (87% vs 80%, p = 0.668, log-rank test).

CONCLUSIONS

Patients who underwent primary TSR of NFPMAs experienced higher rates of SIADH than those who underwent revision TSR. Patients who underwent revision TSR were less likely to have GTR of their tumor, although they still had a PFS rate similar to that in patients who underwent primary TSR. This finding may be attributable to an increased rate of adjuvant radiation treatment to subtotally resected tumors in the revision TSR group.