Pedicle versus lateral mass screws
Alexander R. Vaccaro
Risheng Xu, Lydia Gregg, Sheng-fu Larry Lo, and Philippe Gailloud
Low-flow spinal extradural arteriovenous fistulas (SEAVFs) are frequently misdiagnosed as spinal dural arteriovenous fistulas (SDAVFs), and their true prevalence is unknown. The principal feature distinguishing low-flow SEAVFs from SDAVFs is the location of the shunt, which involves a pouch of epidural plexus in SEAVFs and a radiculomedullary vein (RMV) in SDAVFs. A venous hypertensive myelopathy comparable to the one observed with SDAVFs develops when the arterialized venous pouch of an SEAVF is connected to an RMV. Depending on the size of the epidural pouch, a low-flow SEAVF may uncommonly drain into multiple RMVs. The authors present an observation of a low-flow SEAVF whose double radiculomedullary drainage was revealed only after intraoperative digital subtraction angiography, and they discuss the surgical implications of this anatomical configuration.
Risheng Xu, Daniel M. Sciubba, Ziya L. Gokaslan, and Ali Bydon
Abnormal ossification of spinal ligaments is a well-known cause of myelopathy in East Asian populations, with ossification of the ligamentum flavum (OLF) and the posterior longitudinal ligament being the most prevalent. In Caucasian populations, OLF is rare, and there has been only 1 documented case of the disease affecting more than 5 spinal levels. In this report, the authors describe the clinical presentation, imaging characteristics, and management of the second published case of a Caucasian man with OLF affecting almost the entire thoracic spine. The literature is then reviewed with regard to OLF epidemiology, pathogenesis, presentation, and treatment.
James Feghali, Risheng Xu, Wuyang Yang, Jason Liew, Rafael J. Tamargo, Elisabeth B. Marsh, and Judy Huang
The authors aimed to determine whether differences exist in presentation and natural history when comparing Asian patients with moyamoya disease (MMD) to those of other ethnicities in North America.
A database of 137 patients with MMD presenting to their institution between 1994 and 2015 was reviewed. Baseline characteristics and outcome variables, including stroke and functional outcome, were compared between Asian and non-Asian patients. Unadjusted Kaplan-Meier survival analysis and adjusted Cox regression models were used to compare stroke-free survival and stroke hazard after diagnosis among hemispheres of both racial groups. The analysis was stratified by age group, and censoring was performed until last follow-up or at the time of surgery. Because the relative rate of stroke changed between Asian and non-Asian adults after 1.5 years of follow-up, a time-segmented analysis focusing on the period 1.5 years after diagnosis was performed.
The cohort comprised 23% (31/137) Asian and 77% (106/137) non-Asian patients with MMD with a bimodal age distribution. Non-Asian patients had a higher prevalence of increased BMI (p = 0.02) and smoking (p = 0.04). Among patients who presented with stroke (n = 90), hemorrhage was significantly more common among Asians (p = 0.02). The natural history analysis included 250 hemispheres: 67 pediatric and 183 adult hemispheres. The overall mean follow-up duration since diagnosis was 3.3 years. Among adults, Asian patients had a higher incidence of stroke (8.0 per 100 person-years vs 3.0 per 100 person-years) over a mean follow-up of 3.3 years, but results were not statistically significant (p = 0.45). In the period beginning 1.5 years after diagnosis, Asian adults had a significantly higher hazard of stroke over a mean follow-up of 7.7 years, while controlling for sex, hypertension, and stroke before diagnosis (hazard ratio 8.8, p = 0.02). Among pediatric patients, Asians also had a higher stroke incidence (10.0 per 100 person-years vs 3.5 per 100 person-years) over a mean follow-up of 3.2 years; however, results did not reach statistical significance (p = 0.40). Functional outcome was similar between both ethnic groups at last follow-up (p = 0.57).
This study suggests a comparatively more progressive course of MMD in Asians. Further studies are required to fully characterize the phenotypic distinctions between different races and underlying pathophysiological mechanisms.
Risheng Xu, Mohamad Bydon, Ziya L. Gokaslan, Jean-Paul Wolinsky, Timothy F. Witham, and Ali Bydon
Epidural steroid injections are relatively safe procedures, although the risk of hemorrhagic complications in patients undergoing long-term anticoagulation therapy is higher. The American Society for Regional Anesthesia and Pain Medicine has specific guidelines for treatment of these patients when they undergo neuraxial anesthetic procedures. In this paper, the authors present a case in which the current American Society for Regional Anesthesia and Pain Medicine guidelines were strictly followed with respect to withholding and reintroducing warfarin and enoxaparin after an epidural steroid injection, but the patient nevertheless developed a spinal epidural hematoma requiring emergency surgical evacuation. The authors compare the case with the 8 other published cases of postinjection epidural hematomas in patients with coagulopathy, and the specific risk factors that may have contributed to the hemorrhagic complication in this patient is analyzed.
Scott L. Parker, Risheng Xu, Matthew J. McGirt, Timothy F. Witham, Donlin M. Long, and Ali Bydon
The most common spinal procedure performed in the US is lumbar discectomy for disc herniation. Longterm disc degeneration and height loss occur in many patients after lumbar discectomy. The incidence of mechanical back pain following discectomy varies widely in the literature, and its associated health care costs are unknown. The authors set out to determine the incidence of and the health care costs associated with mechanical back pain attributed to segmental degeneration or instability at the level of a prior discectomy performed at their institution.
The authors retrospectively reviewed the data for 111 patients who underwent primary, single-level lumbar hemilaminotomy and discectomy for radiculopathy. All diagnostic modalities, conservative therapies, and operative treatments used for the management of postdiscectomy back pain were recorded. Institutional billing and accounting records were reviewed to determine the billed costs of all diagnostic and therapeutic measures.
At a mean follow-up of 37.3 months after primary discectomy, 75 patients (68%) experienced minimal to no back pain, 26 (23%) had moderate back pain requiring conservative treatment only, and 10 (9%) suffered severe back pain that required a subsequent fusion surgery at the site of the primary discectomy. The mean cost per patient for conservative treatment alone was $4696. The mean cost per patient for operative treatment was $42,554. The estimated cost of treatment for mechanical back pain associated with postoperative same-level degeneration or instability was $493,383 per 100 cases of first-time, single-level lumbar discectomy ($4934 per primary discectomy).
Postoperative mechanical back pain associated with same-level degeneration is not uncommon in patients undergoing single-level lumbar discectomy and is associated with substantial health care costs.
Andrew C. Vivas, Nir Shimony, Eric M. Jackson, Risheng Xu, George I. Jallo, Luis Rodriguez, Gerald F. Tuite, and Carolyn M. Carey
Hydrocephalus associated with subdural hygromas is a rare complication after decompression of Chiari malformation type I (CM-I). There is no consensus for management of this complication. The authors present a series of 5 pediatric patients who underwent CM-I decompression with placement of a dural graft complicated by posterior fossa hygromas and hydrocephalus that were successfully managed nonoperatively.
A retrospective review over the last 5 years of patients who presented with hydrocephalus and subdural hygromas following foramen magnum decompression with placement of a dural graft for CM-I was conducted at 2 pediatric institutions. Their preoperative presentation, perioperative hospital course, and postoperative re-presentation are discussed with attention to their treatment regimen and ultimate outcome. In addition to reporting these cases, the authors discuss all similar cases found in their literature review.
Over the last 5 years, the authors have encountered 194 pediatric cases of CM-I decompression with duraplasty equally distributed at the 2 institutions. Of those cases, 5 pediatric patients with a delayed postoperative complication involving hydrocephalus and subdural hygromas were identified. The 5 patients were managed nonoperatively with acetazolamide and high-dose dexamethasone; dosages of both drugs were adjusted to the age and weight of each patient. All patients were symptom free at follow-up and exhibited resolution of their pathology on imaging. Thirteen similar pediatric cases and 17 adult cases were identified in the literature review. Most reported cases were treated with CSF diversion or reoperation. There were a total of 4 cases previously reported with successful nonoperative management. Of these cases, only 1 case was reported in the pediatric population.
De novo hydrocephalus, in association with subdural hygromas following CM-I decompression, is rare. This presentation suggests that these complications after posterior fossa decompression with duraplasty can be treated with nonoperative medical management, therefore obviating the need for CSF diversion or reoperation.
James Feghali, Risheng Xu, Wuyang Yang, Jason Anthony Liew, Jaishri Blakeley, Edward S. Ahn, Rafael J. Tamargo, and Judy Huang
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.
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.
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).
MMD and MMS have largely comparable clinical and angiographic phenotypes with analogously favorable responses to surgical revascularization.
Mohamad Bydon, Risheng Xu, Kyriakos Papademetriou, Daniel M. Sciubba, Jean-Paul Wolinsky, Timothy F. Witham, Ziya L. Gokaslan, George Jallo, and Ali Bydon
Unintended durotomies are a common complication of spine surgery and are often correlated with increased postoperative morbidity. Recently, ultrasonic bone curettes have been introduced in spine surgery as a possible alternative to the conventional high-speed drill, offering the potential for greater bone-cutting precision and less damage to surrounding soft tissues. To date, however, few studies have investigated the safety and efficacy of the ultrasonic bone curette in reducing the rates of incidental durotomy compared with the high-speed drill.
The authors retrospectively reviewed the records of 337 consecutive patients who underwent posterior cervical or thoracic decompression at a single institution between January 2009 and September 2011. Preoperative pathologies, the location and extent of spinal decompression, and the use of an ultrasonic bone curette versus the high-speed drill were noted. The rates of incidental durotomy, as well as hospital length of stay (LOS) and perioperative outcomes, were compared between patients who were treated using the ultrasonic bone curette and those treated using a high-speed drill.
Among 88 patients who were treated using an ultrasonic bone curette and 249 who were treated using a high-speed drill, 5 (5.7%) and 9 (3.6%) patients had an unintentional durotomy, respectively. This finding was not statistically significant (p = 0.40). No patients in either cohort experienced statistically higher rates of perioperative complications, although patients treated using an ultrasonic bone curette tended to have a longer hospital LOS. This difference may be attributed to the fact that this series contained a statistically higher number of metastatic tumor cases (p < 0.0001) in the ultrasonic bone curette cohort, likely increasing the LOS for that patient population. In 13 patients, the dural defect was repaired intraoperatively. No patients who experienced an incidental durotomy had new-onset or permanent neurological deficits postoperatively.
The safety and efficacy of ultrasonic bone curettes in spine surgery has not been well established. This study shows that the ultrasonic bone curette has a similar safety profile compared with the high-speed drill, although both are capable of causing iatrogenic dural tears during spine surgery.
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
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.
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.
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.
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.