1. Perez-Roman RJ, Shelby Burks S, Debs L, et al. The risk of peripheral nerve tumor biopsy in suspected benign etiologies. Neurosurgery 2020;86:E326–32. doi:10.1093/neuros/nyz549
The authors evaluated the neurological risks of preoperative biopsy in benign PNSTs. Surgical cases were collected retrospectively using a prospectively established database of PNSTs treated by a single surgeon between 1997-2019. Patients were dichotomized depending on preoperative biopsy. A total of 151 cases were included. Only 23.2% (35) of patients underwent preoperative biopsy, but 42.9% of these experienced new or worsening neurological examination immediately following biopsy. After definitive resection, the rate of neurological deficit was significantly different between the 2 groups with 60% of biopsy patients and 19% of those patients not biopsied experiencing decline in examination. Univariate logistic regression of neurological deficit with patient age, sex, tumor type, and biopsy status showed that only biopsy was associated with the occurrence of any postoperative deficit. The authors conclude that biopsy of benign PNSTs is associated with a high rate of neurological deficit both immediately following the procedure and after definitive resection. They suspect that preoperative biopsy may cause inflammation and scarring within the lesion, obscuring the planes between normal fascicles and tumor. Without the ability to identify fascicular anatomy, the surgeon’s ability to preserve normal function is impaired. The question becomes not only whether to biopsy, but whether to perform complete resection at all. In many cases, symptomless benign tumors can be watched.
2 figures, 3 tables
2. Azad TD, Duffau H. Limitations of functional neuroimaging for patient selection and surgical planning in glioma surgery. Neurosurg Focus 2020;48:1–5. doi:10.3171/2019.11.FOCUS19769
This is an interesting contrarian review from Johns Hopkins of the utility of fMRI for glioma surgical planning. Let me show you one paragraph to give you a sample:
A key limitation of fMRI is that it does not offer the surgeon the ability to distinguish between compensable areas that can be resected and critical areas that should be surgically preserved. This can result in the underselection of patients for surgery and may increase the likelihood of partial or subtotal resection due to concern for violation of cortical areas deemed functional by fMRI. Southwell et al. reported a series of 58 glioma patients with unifocal supratentorial disease who underwent glioma resection guided by direct electrical stimulation (DES) within 6 months of undergoing a brain biopsy of the same lesion at another institution. They achieved an average extent of resection of nearly 90% with no new postoperative neurological deficits. Their findings suggest that decision-making based solely on preoperative structural or functional imaging is likely inadequate, particularly for cortical lesions. Intraoperative DES, in contrast, offers the ability to accurately identify functional brain regions. The distinction between fMRI and DES is even more pronounced when considering subcortical functional mapping, where DES has demonstrated clinical utility. Multiple studies have demonstrated a reduction in BOLD sensitivity and greater susceptibility to physiological noise when applying fMRI to subcortical mapping.
And here is another:
These tools are derived from cohort-level statistical models and are difficult to apply to individual surgical candidates. The authors agree that advances in algorithms produce functional neuroimaging techniques that may be useful adjuncts to intraoperative DES but remain skeptical that these modalities meaningfully impact glioma surgery. To date, evidence that preoperative DTI or fMRI improves extent of resection, minimizes morbidity, and broadens surgical indications in classically eloquent areas remains scarce.
3. McKiernan EC, Schimanski LA, Muñoz Nieves C, et al. Use of the Journal Impact Factor in academic review, promotion, and tenure evaluations. Elife 2019;8:1–12. doi:10.7554/eLife.47338
The Journal Impact Factor (JIF) was originally developed to help libraries make indexing and purchasing decisions for their journal collections and the metric’s creator, Eugene Garfield, made it clear that the JIF was not appropriate for evaluating individuals or for assessing the significance of individual articles. However, over the past few decades the JIF has increasingly been used as a proxy measure to rank journals – and, by extension, the articles and authors published in these journals. The association between the JIF, journal prestige, and selectivity is strong, and has led academics to covet publications in journals with high JIFs. In some academic disciplines, it is considered necessary to have publications in journals with high JIFs to succeed, especially for those on the tenure track. Institutions in some countries financially reward their faculty for publishing in journals with high JIFs, demonstrating an extreme but important example of how this metric may be grossly distorting academic incentives.
The authors analyzed how often and in what ways the JIF is currently used in review, promotion, and tenure (RPT) documents of a representative sample of universities from the United States and Canada. 40% of research-intensive institutions and 18% of master’s institutions mentioned the JIF, or closely related terms. Of the institutions that mentioned the JIF, 87% supported its use in at least one of their review, promotion, and tenure documents. Only 13% expressed caution about its use, and none heavily criticized it or prohibited its use. Furthermore, 63% of institutions that mentioned the JIF associated the metric with quality, 40% with impact, importance, or significance, and 20% with prestige, reputation, or status. Their results also raise specific concerns that the JIF is being used to evaluate the quality and significance of research, despite the numerous warnings against such use.
1 figure, 2 tables
4. Jadhav AP, Desai SM, Liebeskind DS, et al. Neuroimaging of acute stroke. Neurol Clin 2020;38:185–99. doi:10.1016/j.ncl.2019.09.004
This is a nice review, sort-of a basic primer on imaging in acute stroke and would be appropriate for residents and fellows. The review covers CT/MR all the way from noncontrast head CT and hyperdense MCA sign to MR and MRA.
13 figures, 1 table
5. Le Huec JC, Thompson W, Mohsinaly Y, et al. Sagittal balance of the spine. Eur Spine J 2019;28:1889–1905. doi:10.1007/s00586-019-06083-1
This is an excellent and very comprehensive review of an important area that most of use try to ignore and probably much more information than most of us want to know (but is critical to the spine surgeon). The analysis of sagittal balance requires radiographic anteroposterior and lateral views of the entire spine in standing and relaxed positions, from C2 to the femoral heads. The position must also be standardized: hands resting on collarbones. These radiographs can be made on large cassettes or with the EOS imaging system. The EOS imaging system enables images of the entire spine while considerably reducing the radiation dose and is much faster than with traditional imaging systems.
Overall assessment of balance can be performed using different parameters:
The C7 plumb line is the lowered vertical line of C7. Ideally it must pass through the sacral endplate, but even if this is the case, it does not imply that the spino-pelvic parameters are adequate: The spine can be in (compensated) balance, but spino-pelvic parameters can be inadequate (not aligned). The sagittal vertical axis or SVA which corresponds to the horizontal distance between the C7 plumb line and the posterior–superior S1 corner. The SVA is correlated with quality-of-life parameters. The normal SVA should be less than 5 cm, but this parameter is likely age-dependent.
Spino-sacral angle or SSA is defined by the angle connecting the center of the C7 vertebra to the center of the S1 endplate and the line parallel to the superior S1 endplate. Its normal value is 135 degrees plus/minus 8 degrees. This is an intrinsic parameter of balance because it integrates the C7 position with a pelvic parameter: the sacral slope.
22 figures
6. Capoor MN, Birkenmaier C, Wang JC, et al. A review of microscopy-based evidence for the association of Propionibacterium acnes biofilms in degenerative disc disease and other diseased human tissue. Eur Spine J 2019;28:2951–71. doi:10.1007/s00586-019-06086-y
This is an interesting review article on a controversial topic. Recent research shows an increasing recognition that organisms not traditionally considered infectious in nature contribute to disease processes. Propionibacterium acnes (P. acnes) is a gram-positive, aero-tolerant anaerobe prevalent in the sebaceous gland-rich areas of the human skin. A ubiquitous slow-growing organism with the capacity to form biofilm, P. acnes, recognized for its role in acne vulgaris and medical device-related infections, is now also linked to a number of other human diseases.
This literature review considers a range of microscopy-based studies that provides definitive evidence of P. acnes colonization within tissue from a number of human diseases (acne vulgaris, degenerative disc and prostate disease and atherosclerosis).
The authors are convinced that these findings represent true infection/ colonization, and not instances of contamination. While the microscopy findings that implicate P. acnes in acne vulgaris may not be a surprise, similar findings in DDD, prostate disease and atherosclerosis support the emerging recognition of P. acnes as an opportunistic pathogen in other human diseases. Although association does not imply causation, it at least provides an initial platform for further evidence-based studies. Of particular relevance are the findings related to DDD since spine-related degeneration and its symptomatology are leading causes of disability worldwide; thus, treatments that prevent degeneration in even a portion of those affected would have a significant effect on the global population.
5 figures, 10 tables
7. Chow LQM. Head and neck cancer. N Engl J Med 2020;382:60–72. doi:10.1056/NEJMra1715715
Excellent review which again should be a must read for residents and fellows.
Head and neck cancer was the seventh most common cancer worldwide in 2018 (890,000 new cases and 450,000 deaths), accounting for 3% of all cancers (51,540 new cases) and just over 1.5% of all cancer deaths (10,030 deaths) in the United States. Typically diagnosed in older patients in association with heavy use of tobacco and alcohol, head and neck cancers are slowly declining globally, in part because of decreased use of tobacco.
In contrast, cases of HPV-associated oropharyngeal cancer, induced primarily by HPV type 16, are increasing, predominantly among younger people in North America and northern Europe, reflecting a latency of 10 to 30 years after oral-sex exposure. The fraction of head and neck cancers diagnosed as HPV-positive oropharyngeal cancers in the United States rose from 16.3% in the 1980s to more than 72.7% in the 2000s. This review goes through staging, treatment (early stage and advanced), use of chemo and radiotherapy, and adjuvant therapy.
2 figures, 2 tables
8. Eross L, Riley J, Levy EI, et al. Neuroimaging of deep brain stimulation. Neurol Clin 2020;38:201–14. doi:10.1016/j.ncl.2019.09.005
Nice review covering anatomy, different use cases and targets, and intervention.
They note that the introduction of proton density imaging provides high contrast rate between the intramedullary lamina and the intranuclear gray matter, making it possible to distinguish between the internal part of the globus pallidus (GPi) and external part of the globus pallidus, making the stereotactic target for dystonia (DT) and in some cases of PD more identifiable. T2, susceptibility weighted imaging, and quantitative susceptibility mapping can identify the iron content within the subthalamic nucleus (STN), red nucleus, the GP, and the substantia nigra making them more distinguishable from the surrounding regions, thus providing optimal target identification in PD. Double inversion recovery sequences using different inversion times can create two image sets in the same coregistered space, one with nulled white matter signal and another with nulled cerebrospinal fluid intensity. On the resulting images the intramedullary lamina within the GP or other important anatomic markers, such as mammillothalamic tract, are clearly differentiated making the anterior nucleus of the thalamus [ANT] more outlined for epilepsy DBS.
5 figures
