Tracy Ma

Outcome comparison of atlantoaxial fusion with transarticular screws and screw-rod constructs: meta-analysis and review of literature.

Study Design: Literature review and meta-analysis. Objective: To compare clinical and radiographic outcomes of patients treated with transarticular screws (TASs) and screw-rod constructs (SRCs) for posterior atlantoaxial fusion. Background: Modern techniques for C1–C2 fusions include Magerl and Seeman’s TAS and SRC using C1 lateral mass screws and C2 pars/pedicle screws as described by Goel and Laheri and later modified by Harms and Melcher. Materials and Methods: Online databases were searched for English-language articles between 1986 and April 2011 describing posterior atlantoaxial instrumentation with C1–C2 TAS or SRC. Forty-five studies (2073 patients) treated with TAS and 24 studies (1073 patients) treated with SRC fulfilled inclusion criteria. Standard and formal meta-analysis techniques were used to compare the outcomes. Results: All studies provided class III evidence. There were no differences in 30-day mortality (0.8% vs. 0.6%) or neurological injury (0.2% vs. 0%). There was a higher incidence of vertebral artery injury [4.1% (95% confidence interval (CI), 2.8%–5.4%) vs. 2.0% (95% CI, 1.1%–3.4%); P=0.02] and malpositioned screws [7.1% (95% CI, 5.7%–8.8%) vs. 2.4% (95% CI, 1.1%–4.1%); P<0.001] and a slightly lower rate of fusion with the TAS technique [97.5% (95% CI, 95.9%–98.5%) vs. 94.6% (95% CI, 92.6%–96.1%); P<0.001]. Conclusions: TAS and SRC are safe and effective treatment options for C1–C2 instability but require a thorough knowledge of atlantoaxial anatomy for successful insertion of screws. Slightly higher rates of fusion and less risk of injury to the vertebral artery during screw placement were observed with the SRC technique. However, differences in graft material and techniques were noted. Prospective, randomized studies with validated radiographic and clinical outcome metrics are necessary for proper comparison of these techniques.

Electrocorticographic evidence of perituberal cortex epileptogenicity in tuberous sclerosis complex

OBJECT Tuberous sclerosis complex (TSC) is a multisystem autosomal dominant disorder resulting in hamartomas of several organs. Cortical tubers are the most prominent brain lesions in TSC. Treatment-resistant epilepsy often develops early in life in patients with TSC and is associated with severe intellectual and behavioral impairments. Seizures may remit following epilepsy surgery in selected cases, yet it remains unclear whether the tuber or the perituberal cortex is the source of seizure onset. In this study, the authors reviewed the onset of seizures in patients in whom depth electrodes had been placed within or adjacent to cortical tubers. METHODS After obtaining institutional review board approval, the authors retrospectively reviewed data from 12 pediatric patients with multifocal TSC and treatment-resistant epilepsy who had undergone invasive intracranial electroencephalographic monitoring. Tubers were identified on postimplantation MRI, and all depth electrodes were located. Depth electrode contacts were classified visually as either tuber/perituberal cortex or nontuber/nonperituberal cortex. Board-certified clinical neurophysiologists reviewed the seizures to identify all electrodes involved in the ictal onset. RESULTS Among 309 recorded seizures, 104 unique ictal onset patterns were identified. Of the 11 patients with electrodes recording in a tuber, 9 had seizure onsets involving the tuber. Similarly, of the 9 patients with perituberal recording electrodes, 7 had perituberal ictal onsets. Overall, there was no difference in the percentage of contacts involved in seizure onset between the tuber and perituberal cortex. In a subset of 7 patients in whom at least 1 depth electrode contact was within the tuber and 1 was in the perituberal cortex, there was no difference between the percentage of tuber and perituberal onsets. CONCLUSIONS Findings demonstrated heterogeneity in the ictal onset patterns as well as involvement of the tuber and perituberal cortex within and between patients. Although the data are limited by the restricted region(s) sampled with intracranial electrodes, they do suggest that cortical hyperexcitability in TSC may derive from the tuber or surrounding cortex.

Atlantoaxial Fusion with Screw-Rod Constructs: Meta-Analysis and Review of Literature

OBJECTIVE To review published series describing C1-2 posterior instrumented fusions and summarize clinical and radiographic outcomes of patients treated with screw-rod constructs (SRC). METHODS Online databases were searched for English-language articles published between 1991 and April 2011 describing posterior atlantoaxial instrumentation with C1-2 SRC. There were 24 studies including 1073 patients treated with SRC that fulfilled inclusion criteria. Meta-analysis techniques were used to compare outcomes. RESULTS All studies provided class III evidence. The 30-day perioperative mortality rate was 0.6%, and neurologic injury occurred in two patients with vertebral artery injury (VAI) from screw malpositions (0.2%). The incidence of clinically significant screw malpositions was 2.4% (confidence interval [CI], 1.1%-4.1%), the incidence of VAI was 2.0% (CI, 1.1%-3.4%), and the rate of fusion with the SRC technique was 97.5% (CI, 95.9%-98.5%). CONCLUSIONS SRC is a safe and effective treatment option for C1-2 instability. The low but nonzero incidence of screw malposition and VAI emphasizes the necessity of having a thorough knowledge of atlantoaxial anatomy for successful insertion of screws.

Direct versus indirect revascularization procedures for moyamoya disease: a comparative effectiveness study.

OBJECTIVE Moyamoya disease (MMD) is a chronic cerebrovascular disease that can lead to devastating neurological outcomes. Surgical intervention is the definitive treatment, with direct, indirect, and combined revascularization procedures currently employed by surgeons. The optimal surgical approach, however, remains unclear. In this decision analysis, the authors compared the effectiveness of revascularization procedures in both adult and pediatric patients with MMD. METHODS A comprehensive literature search was performed for studies of MMD. Using complication and success rates from the literature, the authors constructed a decision analysis model for treatment using a direct and indirect revascularization technique. Utility values for the various outcomes and complications were extracted from the literature examining preferences in similar clinical conditions. Sensitivity analysis was performed. RESULTS A structured literature search yielded 33 studies involving 4197 cases. Cases were divided into adult and pediatric populations. These were further subdivided into 3 different treatment groups: indirect, direct, and combined revascularization procedures. In the pediatric population at 5- and 10-year follow-up, there was no significant difference between indirect and combination procedures, but both were superior to direct revascularization. In adults at 4-year follow-up, indirect was superior to direct revascularization. CONCLUSIONS In the absence of factors that dictate a specific approach, the present decision analysis suggests that direct revascularization procedures are inferior in terms of quality-adjusted life years in both adults at 4 years and children at 5 and 10 years postoperatively, respectively. These findings were statistically significant (p < 0.001 in all cases), suggesting that indirect and combination procedures may offer optimal results at long-term follow-up.

Comparison of screw malposition and vertebral artery injury of C2 pedicle and transarticular screws: meta-analysis and review of the literature.

Study Design: Literature review and meta-analysis. Objectives: To compare the incidence of screw malposition and vertebral artery injury (VAI) with transarticular screws (TAS) and C2 pedicle screws (C2PS) using meta-analysis techniques. Summary of Background Data: Posterior instrumentation for atlantoaxial fusions can be challenging and risky. Some centers report a higher incidence of VAI with the implantation of TAS compared with C2PS, whereas other data do not support this. Methods: Online databases were searched for English language articles between 1994 and April 2011 describing the clinical and radiographic outcomes after insertion of C2PS or TAS. Forty-one studies reporting on 3627 TAS and 33 studies describing 2979 C2PS met inclusion criteria for VAI or clinically significant misplacements (VAI, neurological deficits, or misplacements requiring surgical revision), and 36 studies reporting on 3280 TAS and 28 studies describing 2532 C2PS met inclusion criteria for radiographic misplacement outcomes. Results: All studies comprised class III evidence. VAI occurred in 26 of 3627 (0.72%) implanted TAS and in 10 of 2979 (0.34%) implanted C2PS (P=0.01). Clinically significant misplacements occurred in 67 TAS (1.84%) and in 10 C2PS (0.34%; P<0.0001). The point estimate of VAI for TAS was 1.68% [confidence interval (CI), 1.23%–2.29%] and was higher than C2PS (1.09%; CI, 0.73%–1.63%; P=0.01). The point estimate of clinically significant screw malposition for TAS was 2.33% (CI, 1.61%–3.37%) and was higher than that of C2PS (1.15%; CI, 0.77%–1.70%; P<0.001). Conclusions: With training, experience, and anatomic knowledge, both TAS and C2PS can be inserted accurately and safely. However, improper insertion and VAI can have catastrophic consequences. Our review identified a higher risk of VAI, neurological injury, and clinically significant malpositions with TAS compared with C2PS. These data provide preliminary support for the supposition that C2PS have a lower risk of morbidity.

Epilepsy control following intracranial monitoring without resection in young children.

Purpose:  Intracranial monitoring (IM) is a key diagnostic procedure for select patients with treatment‐resistant epilepsy (TRE). Seizure focus resection may improve seizure control in both lesional and nonlesional TRE. IM itself is not considered to have therapeutic potential. We describe a cohort of patients with improved seizure control following IM without resective surgery.

Ultrasonographic Evaluation of Peripheral Nerves

There are a variety of imaging modalities for evaluation of peripheral nerves. Of these, ultrasonography (US) is often underused. There are several advantages of this imaging modality, including its cost-effectiveness, time-efficient assessment of long segments of peripheral nerves, ability to perform dynamic maneuvers, lack of contraindications, portability, and noninvasiveness. It can provide diagnostic information that cannot be obtained by electrophysiologic or, in some cases, magnetic resonance imaging studies. Ideally, the neurosurgeon can use US as a diagnostic adjunct in the preoperative assessment of a patient with traumatic, neoplastic, infective, or compressive nerve injury. Perhaps its most unique use is in intraoperative surgical planning. In this article, a brief description of normal US nerve anatomy is presented followed by a description of the US appearance of peripheral nerve disease caused by trauma, tumor, infection, and entrapment.

Is External Cervical Orthotic Bracing Necessary After Posterior Atlantoaxial Fusion with Modern Instrumentation: Meta-Analysis and Review of Literature

BACKGROUND No guidelines exist regarding external cervical orthoses (ECO) after atlantoaxial fusion. We reviewed published series describing C1-2 posterior instrumented fusions with screw-rod constructs (SRC) or transarticular screws (TAS) and compared rates of fusion with and without postoperative ECO. METHODS Online databases were searched for English-language articles between 1986 and April 2011 describing ECO use after posterior atlantoaxial instrumentation with SRC or TAS. Eighteen studies describing 947 patients who had SRC (± ECO: 254 of 693 patients), and 33 studies describing 1424 patients with TAS (± ECO: 525 of 899 patients) met inclusion criteria. Meta-analysis techniques were applied to estimate rates of fusion with and without ECO use. RESULTS All studies provided class III evidence, and no studies directly compared outcomes with or without ECO use. There was no significant difference in the proportion of patients who achieved successful fusion between patients treated with ECO and without ECO for SRC or TAS patients. Point estimates and 95% confidence intervals (CI) for rates of fusion ± ECO were 97.4% (CI: 95.2% to 98.6%) versus 97.9% (CI: 93.6% to 99.3%) for SRC and 93.6% (CI: 90.7% to 95.6%) versus 95.3% (CI: 90.8% to 97.7%) for TAS. There was no correlation between duration of ECO treatment and fusion (dose effect). CONCLUSIONS After C1-2 fusion with modern instrumentation, ECO may be unnecessary (class III). Some centers recommend ECO use with patients with softer bone quality (class IV). Prospective, randomized studies with validated radiographic and clinical outcome metrics are necessary to determine the utility of ECO after C1-2 fusion and its impact on patient comfort and cost.

Pre-optimization of spinal surgery patients: Development of a neurosurgical enhanced recovery after surgery (ERAS) protocol

OBJECTIVE Despite surgical, technological, medical, and anesthetic improvements, patient outcomes following elective neurosurgical procedures can be associated with high morbidity. Enhanced recovery after surgery (ERAS) protocols are multimodal care pathways designed to optimize patient outcomes by addressing pre-, peri-, and post-operative factors. Despite significant data suggesting improved patient outcomes with the adoption of these pathways, development and implementation has been limited in the neurosurgical population. METHODS/RESULTS This study protocol was designed to establish the feasibility of a randomized controlled trial to assess the efficacy of implementation of an ERAS protocol on the improvement of clinical and patient reported outcomes and patient satisfaction scores in an elective inpatient spine surgery population. Neurosurgical patients undergoing spinal surgery will be recruited and randomly allocated to one of two treatment arms: ERAS protocol (experimental group) or hospital standard (control group). The experimental group will undergo interventions at the pre-, peri-, and post-operative time points, which are exclusive to this group as compared to the hospital standard group. CONCLUSIONS The present proposal aims to provide supporting data for the application of these specific ERAS components in the spine surgery population and provide rationale/justification of this type of care pathway. This study will help inform the design of a future multi-institutional, randomized controlled trial. RESULTS of this study will guide further efforts to limit post-operative morbidity in patients undergoing elective spinal surgery and to highlight the impact of ERAS care pathways in improving patient reported outcomes and satisfaction.

A simplified pressure adjustment clinical pathway for programmable valves in NPH patients

OBJECTIVE The goal of this study is to provide a clinical pathway for shunt valve adjustment in the treatment of normal pressure hydrocephalus (NPH) patients. PATIENT AND METHODS The authors conducted a single-center retrospective study of 102 patients (mean age 74 years, 66 men, 36 women) diagnosed with NPH. In all cases, a Medtronic Strata Adjustable Pressure valve set initially at 1.5 was implanted. Outcome was based on the clinical status of the patient at the last contact point with the senior author. Patients were adjusted with reductions or increases of 0.5 per follow-up visit to achieve the best clinical outcome and avoid complications. Complications were categorized as infection, shunt malfunction, subdural hygroma/hematoma, or any adverse event able to be attributed to a change in shunt setting or surgical procedure. RESULTS Of the 102 patients, 60% had the triad of clinical symptoms, 5% had gait dysfunction only, 2% had dementia only, 4% had urine incontinence and gait dysfunction, 1% had urine incontinence and dementia, and 28% had gait dysfunction and dementia. Over a mean clinical follow-up of 19 months, 71 patients had improvement or resolution of NPH symptoms at the last point of contact with the senior author. Of the 71 patients, 24% improved in all 3 symptoms, 8% improved in urine incontinence only, 17% improved in gait dysfunction only, 15% improved in dementia only, 15% improved in urine incontinence and gait dysfunction only, 4% improved in urine incontinence and dementia only, and 15% improved in gait dysfunction and dementia only. Valve pressure adjustment was required at least once in 85 patients (mean number of 1.68 adjustments, 7 maximum); 10% had 0.5 as the final setting, 47% had 1.0 as the final setting, 36% had 1.5 as the final setting, 7% had 2.0 as the final setting, and 0% had 2.5 as the final setting. There were 41 (40%) complications overall: 28 subdural hygromas/hematomas, of which 5 required surgical evacuation; 9 distal obstructions requiring surgical revision; 4 seizures; 2 infections; 1 exposed shunt tubing; 1 intraparenchymal hematoma of unknown etiology. CONCLUSION Standardization of post-operative care for patients with NPH is possible. The present manuscript offers a safe and effective pathway for treatment of NPH patients with the Strata Adjustable Pressure Valve.