Image-localized biopsy mapping of brain tumor heterogeneity: A single-center study protocol

Brain cancers pose a novel set of difficulties due to the limited accessibility of human brain tumor tissue. For this reason, clinical decision-making relies heavily on MR imaging interpretation, yet the mapping between MRI features and underlying biology remains ambiguous. Standard (clinical) tissue sampling fails to capture the full heterogeneity of the disease. Biopsies are required to obtain a pathological diagnosis and are predominantly taken from the tumor core, which often has different traits to the surrounding invasive tumor that typically leads to recurrent disease. One approach to solving this issue is to characterize the spatial heterogeneity of molecular, genetic, and cellular features of glioma through the intraoperative collection of multiple image-localized biopsy samples paired with multi-parametric MRIs. We have adopted this approach and are currently actively enrolling patients for our 'Image-Based Mapping of Brain Tumors' study. Patients are eligible for this research study (IRB #16-002424) if they are 18 years or older and undergoing surgical intervention for a brain lesion. Once identified, candidate patients receive dynamic susceptibility contrast (DSC) perfusion MRI and diffusion tensor imaging (DTI), in addition to standard sequences (T1, T1Gd, T2, T2-FLAIR) at their presurgical scan. During surgery, sample anatomical locations are tracked using neuronavigation. The collected specimens from this research study are used to capture the intra-tumoral heterogeneity across brain tumors including quantification of genetic aberrations through whole-exome and RNA sequencing as well as other tissue analysis techniques. To date, these data (made available through a public portal) have been used to generate, test, and validate predictive regional maps of the spatial distribution of tumor cell density and/or treatment-related key genetic marker status to identify biopsy and/or treatment targets based on insight from the entire tumor makeup. This type of methodology, when delivered within clinically feasible time frames, has the potential to further inform medical decision-making by improving surgical intervention, radiation, and targeted drug therapy for patients with glioma.

Retrospective radiographic analysis of anterior lumbar fusion for high grade lumbar spondylolisthesis

BACKGROUND

High-grade spondylolisthesis (>50% slippage) is infrequently encountered in adults and frequently requires surgical treatment. The optimal surgical treatment is controversial with limited literature guidance as to optimal approach to treatment. An observational study to examine the technique and radiographic outcomes of adult patients treated with anterior lumbar interbody fusion (ALIF) and posterior percutaneous instrumentation for high-grade spondylolisthesis.

METHODS

ALIF was performed in 5 consecutive patients (3/5 female, 2/5 male) aged 29-67 years old who presented with low back pain and L5 radiculopathy. All patients failed conservative treatment and were treated with L4-5 and L5-S1 ALIF followed by posterior percutaneous L4-S1 pedicle screw and rod fixation. Pre- and postoperative clinical data was collected including L5-S1 posterior disk height in millimeters, millimeters of spondylolisthesis at L5-S1, degrees of segmental lordosis (L4-S1), lumbar lordosis (L1-S1), and lumbar lordosis pelvic incidence (LL-PI) mismatch.

RESULTS

Six weeks following surgery, no patient reported residual L5 radicular symptoms. At last follow up, patient satisfaction, according to Modified Macnab Criteria, was excellent in 4/5 patients and good in 1/5 patient. In the 4 patients with greater than 1 year radiographic follow up, fusion rate was 100% on computed tomography (CT). Mean increase in posterior disk height was 12.5 mm (range, 11.4-13.5 mm). Mean reduction in spondylolisthesis was 58.7% (range, 20.2-100%). Mean segmental (L4-S1) and overall (L1-S1) lumbar lordosis increased by 23.6% (range, 6.5-41.7%) and 16.6% (2.5-31.5%), respectively. Following surgery, LL-PI mismatch decreased from a mean of 16.4 to 10.2 degrees.

CONCLUSIONS

ALIF with posterior percutaneous instrumentation is a safe and effective treatment for high-grade lumbosacral spondylolisthesis in properly selected adults. This technique improves lumbar sagittal parameters and reduces spondylolisthesis. The indirect neural decompression from simultaneous disk height restoration and spondylolisthesis reduction may be associated with lower neurological injury rate compared to posterior-only. Future prospective study is needed to validate this hypothesis.

Use of transparent plastic tubular retractor in surgery for deep brain lesions: a case series

Brain tissue retraction is frequently required to reach deep intra-axial lesions, and the quest for an ideal retractor that would protect the underlying brain tissue continues. Despite the availability of multiple retractors, the incidence of brain retraction injury remains high and has been reported to be 5% to 10%. A recently developed transparent tubular retractor appears to provide several advantages in surgery for deep intra-axial tumors and intracerebral hematomas. We used a new commercially available transparent tubular retractor in 16 craniotomies. Fourteen of these patients were operated upon for deep tumors and cysts, including two intraventricular tumors and two for deep intracerebral hemorrhages. In all patients, the tubular retractor was directed toward the lesion through a small corticotomy and guided by a navigation system. Each lesion was completely removed through the retractor's lumen. In all cases, the tubular retractors provided excellent visualization of the underlying pathology and facilitated its surgical removal, dissection, and hemostasis. The tubular nature of the retractor allowed the rotation and changing the angle of approach without putting extra pressure on the brain tissue, which inevitably occurs when malleable or other ribbon-type retractors are used. There were no hematomas on routine postoperative CT scans in this series. Transparent tubular retractors provide a unique means of deep visualization and even force distribution at the retracted brain tissue. Although these retractors were originally designed for the removal of deep subcortical tumors, they may be used to access and evacuate intracerebral hematomas. In our experience, the use of tubular retractors allows one to achieve safe access to deep intracerebral lesions and decreases the rate of retraction-related complications.

Subacute subdural hematoma in a 45-year-old woman with no significant past medical history after a roller coaster ride

Amusement park ride injuries have been newsworthy events for many years. The multitude and severity of these injuries has been reported many times over the past 20 years and includes spinal cord and vertebral injuries, subarachnoid hemorrhage, internal and vertebral artery dissections, and even a few cases of subdural hematoma (SDH). There has also been as many theories to explain these injuries as there have been injuries themselves including how G forces and rotational acceleration can cause both neuroparenchymal and neurovascular injury.