Alexander Mason

The accuracy of pedicle screw placement using intraoperative image guidance systems

OBJECT Several retrospective studies have demonstrated higher accuracy rates and increased safety for navigated pedicle screw placement than for free-hand techniques; however, the accuracy differences between navigation systems has not been extensively studied. In some instances, 3D fluoroscopic navigation methods have been reported to not be more accurate than 2D navigation methods for pedicle screw placement. The authors of this study endeavored to identify if 3D fluoroscopic navigation methods resulted in a higher placement accuracy of pedicle screws. METHODS A systematic analysis was conducted to examine pedicle screw insertion accuracy based on the use of 2D, 3D, and conventional fluoroscopic image guidance systems. A PubMed and MEDLINE database search was conducted to review the published literature that focused on the accuracy of pedicle screw placement using intraoperative, real-time fluoroscopic image guidance in spine fusion surgeries. The pedicle screw accuracy rates were segregated according to spinal level because each spinal region has individual anatomical and morphological variations. Descriptive statistics were used to compare the pedicle screw insertion accuracy rate differences among the navigation methods. RESULTS A total of 30 studies were included in the analysis. The data were abstracted and analyzed for the following groups: 12 data sets that used conventional fluoroscopy, 8 data sets that used 2D fluoroscopic navigation, and 20 data sets that used 3D fluoroscopic navigation. These studies included 1973 patients in whom 9310 pedicle screws were inserted. With conventional fluoroscopy, 2532 of 3719 screws were inserted accurately (68.1% accuracy); with 2D fluoroscopic navigation, 1031 of 1223 screws were inserted accurately (84.3% accuracy); and with 3D fluoroscopic navigation, 4170 of 4368 screws were inserted accurately (95.5% accuracy). The accuracy rates when 3D was compared with 2D fluoroscopic navigation were also consistently higher throughout all individual spinal levels. CONCLUSIONS Three-dimensional fluoroscopic image guidance systems demonstrated a significantly higher pedicle screw placement accuracy than conventional fluoroscopy or 2D fluoroscopic image guidance methods.

Prospective, Randomized, Double-Blind Clinical Study Evaluating the Correlation of Clinical Outcomes and Cervical Sagittal Alignment

BACKGROUND:Sagittal alignment of the cervical spine has received increased attention in the literature as an important determinant of clinical outcomes after anterior cervical diskectomy and fusion. Surgeons use parallel or lordotically fashioned grafts depending on preference or simple availability. OBJECTIVE:To quantitatively assess and compare cervical sagittal alignment and clinical outcome when lordotic or parallel allografts were used for fusion. METHODS:A prospective, randomized, double-blind clinical study that enrolled 122 patients was performed. The mean follow-up was 37.5 months (range, 12-54 months). RESULTS:The mean postoperative cervical sagittal alignment was 19° (range, −7°-36°) and 18° (range, −7°-37°) in the lordotic and parallel graft patient groups, respectively. The mean segmental sagittal alignment was 6° (range, −4°-19°) and 7° (range, −3°-19°) in the lordotic and parallel graft patient groups, respectively. There were no statistically significant differences in clinical outcome scores between the lordotic and parallel graft patient groups. However, patients who had maintained or improved segmental sagittal alignment, regardless of graft type, achieved a higher degree of improvement in Short Form-36 Physical Component Summary and Neck Disability Index scores. This was statistically significant (P < .038). CONCLUSION:The use of lordotically shaped allografts does not increase cervical/segmental sagittal alignment or improve clinical outcomes. Maintaining a consistent segmental sagittal alignment or increasing segmental lordosis was related to a higher degree of improvement in clinical outcomes.

EVALUATION OF A NEW BIPOLAR COAGULATION FORCEPS IN A THERMAL DAMAGE ASSESSMENT

OBJECTIVETo determine whether a novel bipolar forceps device that uses heat-pipe technology to manage tissue temperature would result in less tissue injury compared with a conventional antistick forceps design. METHODSIn ex vivo and in vivo experiments, lesions were compared at generator powers of 35 and 50 Malis units and at 3- and 10-second activation times. For the ex vivo studies, lesions were produced in specimens of fresh calf liver. Tissue temperatures were measured by using thermocouples placed in the tissue and also estimated by obtaining thermal photography. Rats were used for the in vivo studies, in which lesions were produced on the surface of the exposed cerebral hemispheres and assessed by histological examination. The extent of tissue injury was determined for both the ex vivo and in vivo studies. RESULTSThermographic and thermometric studies revealed significant tissue temperature reductions at the tips of heat-pipe forceps compared with conventional antistick forceps. In both the ex vivo and in vivo studies, there was less tissue injury produced by the heat-pipe forceps, and this difference was most pronounced with longer activation times. CONCLUSIONBipolar forceps containing heat pipes more effectively limits excessive thermal spread, thereby potentially reducing the risk of unintended injury to collateral or peripheral tissue.

Complications in patients undergoing combined transforaminal lumbar interbody fusion and posterior instrumentation with deformity correction for degenerative scoliosis and spinal stenosis.

Background: Utilization of the transforaminal lumbar interbody fusion (TLIF) approach for scoliosis offers the patients deformity correction and interbody fusion without the additional morbidity associated with more invasive reconstructive techniques. Published reports on complications associated with these surgical procedures are limited. The purpose of this study was to quantify the intra- and postoperative complications associated with the TLIF surgical approach in patients undergoing surgery for spinal stenosis and degenerative scoliosis correction. Methods: This study included patients undergoing TLIF for degenerative scoliosis with neurogenic claudication and painful lumbar degenerative disc disease. The TLIF technique was performed along with posterior pedicle screw instrumentation. The average follow-up time was 30 months (range, 15–47). Results: A total of 29 patients with an average age of 65.9 years (range, 49–83) were evaluated. TLIFs were performed at 2.2 levels on average (range, 1–4) in addition to 6.0 (range, 4–9) levels of posterolateral instrumented fusion. The preoperative mean lumbar lordosis was 37.6° (range, 16°–55°) compared to 40.5° (range, 26°–59.2°) postoperatively. The preoperative mean coronal Cobb angle was 32.3° (range, 15°–55°) compared to 15.4° (range, 1°–49°) postoperatively. The mean operative time was 528 min (range, 276–906), estimated blood loss was 1091.7 mL (range, 150–2500), and hospitalization time was 8.0 days (range, 3–28). A baseline mean Visual Analog Scale (VAS) score of 7.6 (range, 4–10) decreased to 3.6 (range, 0–8) postoperatively. There were a total of 14 (49%) hardware and/or surgical technique related complications, and 8 (28%) patients required additional surgeries. Five (17%) patients developed pseudoarthrosis. The systemic complications (31%) included death (1), cardiopulmonary arrest with resuscitation (1), myocardial infarction (1), pneumonia (5), and pulmonary embolism (1). Conclusion: This study suggests that although the TLIF approach is a feasible and effective method to treat degenerative adult scoliosis, it is associated with a high rate of intra- and postoperative complications and a long recovery process.

Surgical Management of Intracranial Aneurysms in the Endovascular Era : Review Article

The advent of endovascular therapy for intracranial aneurysms and the rapid advances in that field have supplanted microsurgical treatment for many intracranial aneurysms. Applying current outcome data and other parameters, nuances of selecting the modality of treatment for intracranial aneurysms are reviewed. Patient factors, such a age, co-morbidities, vasospasm and other medical conditions, are addressed. A custom-tailored multimodality treatment paradigm for the management of ruptured and unruptured aneurysms will maximize the favorable results seen in this difficult patient population.

The duration of symptoms and clinical outcomes in patients undergoing anterior cervical discectomy and fusion for degenerative disc disease and radiculopathy

BACKGROUND CONTEXT There have been controversial reports published in the literature on the duration of symptoms (DOS) and clinical outcome correlation in patients undergoing anterior cervical discectomy and fusion (ACDF) for painful degenerative disc disease and radiculopathy. PURPOSE The primary purpose of this study was to analyze if the DOS has any effect on clinical outcomes. STUDY DESIGN/SETTING A post hoc analysis was performed on an original prospective clinical study analyzing clinical outcomes and cervical sagittal alignment correlations. PATIENTS SAMPLE Fifty-eight patients undergoing one- or two-level ACDF surgeries for cervical degenerative radiculopathy were analyzed. OUTCOME MEASURES Standardized questionnaires were used to evaluate clinical outcomes. Neck and arm pain was evaluated using (Visual Analog Scale [VAS]). Two scales of Health-Related Quality-of-Life Questionnaire (Short-Form 36 Health Survey [SF-36]) were used for this study: the physical component summary (PCS) and mental component summary (MCS). Neck disability index (NDI) was used to evaluate chronic disability in activities of daily living. The patients completed a self-reported Patient Satisfaction with Results Survey. METHODS Patients who had previous or redo surgeries, were diagnosed with myelopathy or had more than two-level ACDF surgeries were excluded, leaving a total of 58 patients. The mean follow-up was 37.2 months (range 12-54). Patients were divided into two groups for clinical outcome analyses according to the DOS: patients who had surgery within 6 months (n=29) or more than 6 months (n=29) after becoming symptomatic. RESULTS There were no statistically significant differences in any demographic or clinical parameters among the patient groups. Controlling for preoperative scores, the patients who had surgery within 6 months reported significantly higher reduction (p=.04) in arm pain scores compared with the patients who waited more than 6 months. No significant differences were detected in postoperative neck pain VAS (p=.3), NDI (p=.06), SF-36 PCS (p=.08), and MCS (p=.8) scores. CONCLUSIONS Neck and upper extremity pain can be successfully treated conservatively. In those cases, when surgical intervention is pursued, patients with shorter DOS have better improvement in radiculopathy symptoms that is statistically significant.

Preliminary Results on Feasibility of Outpatient Instrumented Transforaminal Lumbar Interbody Fusion

Study Design: A retrospective chart review study was performed. Objective: The primary objective of this study was to analyze our preliminary results to examine whether it is safe and effective to perform instrumented lumbar interbody fusions on an outpatient basis by comparing 2 groups of patients who were discharged the same day versus those who stayed overnight. The secondary objective was to identify the need for prolonged observation for complications that may occur in the immediate postoperative period. Summary of Background Data: There is currently no information in the literature on the safety and complication rates of instrumented transforaminal lumbar interbody fusions performed in an ambulatory surgery setting. Methods: Surgeries were performed at an ambulatory surgery center (n=27) or hospital outpatient departments (n=25). The mean age of patients was 49.8 years (range, 19–72 y). The safety of outpatient lumbar fusions was assessed by analyzing complications that occurred from the moment of discharge up to the seventh postoperative day (0–7 POD), as well as all complications that occurred up to 6 months postoperatively (>7 POD). The efficacy of surgical intervention was also evaluated by assessing change in pain, patient satisfaction scores, and fusion rates. Results: There were no cases of pneumonia, urinary tract infection, or thromboembolic complications. Four patients (14%) who had surgeries performed at an ambulatory surgery center had complications within 7 days postoperatively compared with 1 (4%) patient who had surgery performed at a hospital outpatient department. This difference was not statistically significant (P=0.36, Fisher exact test). Lower back and leg pain was significantly (P<0.0001) decreased postoperatively. The average postoperative back pain was 18.8 (range, 0–90) compared with 74.5 (range, 0–100) preoperatively as measured on a 0–100 visual analog scale. The average postoperative leg pain was 9.1 (range, 0–60) compared with 54.2 (range, 0–100) preoperatively. Conclusions: Although further confirmation is needed, this study discusses the possibility of performing instrumented lumbar interbody fusions with the transforaminal lumbar interbody fusion technique as an outpatient procedure. These results support a future prospective randomized study with a well-defined patient selection criteria.

Aneurysm of a Duplicate Middle Cerebral Artery

BACKGROUND Anatomic middle cerebral artery (MCA) anomalies are rare, but each of the described variants (eg, duplicate, fenestrated, accessory) can be of clinical significance. CASE DESCRIPTION A 34-year-old man with a history of left hemispheric stroke was found to have an aberrant, early-arising duplicate left M1 segment of the MCA with an associated asymptomatic fusiform aneurysm. The patient was treated with a superficial temporal artery (STA) to distal MCA bypass followed by surgical trapping of the aneurysm. RESULTS Intraoperative and follow-up angiography performed postoperatively at 3 months showed complete isolation of the aneurysm from the circulation and patency of the bypass graft. The postoperative course was uneventful with the exception of a craniotomy flap infection, which was effectively managed with intravenous antibiotics, flap removal, and subsequent use of a fabricated replacement. CONCLUSIONS This rare case is presented and used as a framework for a brief discussion of the literature regarding both variant MCA anatomy and treatment considerations for these anomalies when associated with an aneurysm.

Unilateral and Bilateral Pedicle Screw Fixation in Transforaminal Lumbar Interbody Fusion: Radiographic and Clinical Analysis

BACKGROUND Transforaminal lumbar interbody fusion with bilateral segmental pedicle screw (PS) fixation is a widely used and well-recognized technique that provides fixation and load-bearing capacity, while restoring morphometric spine parameters and relieving symptoms in patients with degenerative disc disease. A supplemental interspinous process fixation plate (ISFP) as an adjunct to unilateral PS fixation allows for reduced invasiveness of this technique compared with bilateral PS placement. The biomechanical comparison results have been previously reported, but the significance of these findings has not been studied in clinical settings. METHODS A prospective cohort study with a supplemental retrospective chart review and radiographic analysis was performed. Patients were divided into 2 groups: bilateral PS fixation (n = 75) or unilateral PS fixation + ISFP (n = 96). Lateral lumbar standing radiographs were obtained for preoperative and postoperative foraminal height (FH), disc height, segmental sagittal alignment, and lumbar sagittal alignment measurements. Standardized questionnaires were used to compare postoperative clinical outcomes. RESULTS The estimated blood loss, duration of procedure, and length of hospital stay were significantly lower for 1-level and 2-level procedures in the unilateral PS + ISFP group. A statistically significant mean disc height increase was observed in both groups. Regardless of the disc height increase, a statistically significant FH loss was detected in the bilateral PS group (from 17.1 mm to 16.3 mm; 4.7% loss; P = 0.04) compared with FH height loss in the unilateral PS + ISFP group that was not statistically significant (from 19.0 mm to 18.4 mm; 3.2% loss; P = 0.1). The analysis of segmental sagittal alignment, lumbar sagittal alignment, clinical outcomes, and fusion rates did not demonstrate any statistically significant differences. CONCLUSIONS Significantly reduced surgical invasiveness was associated with unilateral PS + ISFP fixation, which represents the major advantage of this technique. Unilateral fixation was also associated with a slightly lower reduction in FH and was equally effective as bilateral PS fixation in regard to fusion rates, clinical outcomes, and other radiographic outcomes studied.

A Novel Case of Resolved Postherpetic Neuralgia with Subsequent Development of Trigeminal Neuralgia: A Case Report and Review of the Literature

A 72-year-old female patient is presented, who was diagnosed with herpes zoster along the left ophthalmic branch of the trigeminal nerve with associated cutaneous vesicles. The patient subsequently developed postherpetic neuralgia in the same dermatome, which, after remission, transformed into paroxysmal trigeminal pain. The two different symptom sets, with the former consistent with PHN and the later consistent with trigeminal neuralgia, were unique to our practice and the literature.