1. Stevens MN, Gallant JN, Feldman MJ, et al. Management of postradiation late hemorrhage following treatment for HPV-positive oropharyngeal squamous cell carcinoma. Head Neck 2022;44:1079–85. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/35150023/
Acute hemorrhage is an uncommon but potentially deadly complication for patients with head and neck cancer, especially in patients receiving RT. Previous reports have focused on hemorrhage following RT in all head and neck subsites without isolating HPV-positive malignancies. In this article, the authors focus specifically on patients with previously treated HPV-positive OPSCC given (1) the increasing prevalence and survival of this population and (2) the critical role RT plays in its treatment. They detail patient characteristics and cancer treatments leading to hemorrhagic events and include the acute interventions used in these life-threatening situations to better characterize this patient population.
A total of 12 patients with HPV-positive OPSCC were included. Six patients had base of tongue (BoT) tumors and 6 patients had tonsil tumors. The majority of patients were male (83%) with a mean age at diagnosis of 58 years. Fifty percent had advanced primary tumors (T3/T4). Median time from completion of chemoradiation to first hemorrhagic event was 186 days (range 66–1466 days). Seven patients (58%) required intervention to secure their airway. All patients were evaluated for endovascular intervention, 6 (50%) were embolized. Eight patients (67%) had a second hemorrhagic event; median time to second bleed was 22 days (range 3–90 days).
CTA was performed for 11 patients and demonstrated active extravasation in 1 patient, pseudoaneurysm (2), a combination of both extravasation and pseudoaneurysm (1), luminal irregularity (5), and no radiographic indication of vessel abnormality (2).
Seven of the 12 patients in the cohort ultimately required tracheostomy to secure their airway. In this study population, once the airway was established, attention was turned to control of hemorrhage with oropharyngeal packing with or without thrombotic agents, resuscitation with blood products, prompt evaluation with CT angiography, and admission for ongoing observation and management. Given that 3 of the 12 patients were found to have biopsy-proven persistent or recurrent disease, biopsy should be strongly considered in patients with history of HPV-positive OPSCC presenting with oropharyngeal hemorrhage.
3 tables, 2 figures with catheter angio
2. Karandikar P, Massaad E, Hadzipasic M, et al. Machine learning applications of surgical imaging for the diagnosis and treatment of spine disorders: Current state of the art. Neurosurgery 2022;90:372–82. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/35107085/
Recent developments in machine learning (ML) methods demonstrate unparalleled potential for application in the spine. The ability for ML to provide diagnostic faculty, produce novel insights from existing capabilities, and augment or accelerate elements of surgical planning and decision making at levels equivalent or superior to humans will tremendously benefit spine surgeons and patients alike. In this review, the authors aim to provide a clinically relevant outline of ML-based technology in the contexts of spinal deformity, degeneration, and trauma, as well as an overview of commercial-level and precommercial-level surgical assist systems and decision support tools. They briefly discuss potential applications of generative networks.
While discriminative networks represent the bulk of ongoing efforts in medical ML, generative adversarial networks (GANs) are not yet a decade old at the time of writing yet represent a vast and as yet unexplored space for clinical applications. By definition, a generative adversarial network pits generator and discriminator networks against each other, ultimately producing objects that sufficiently imitate the training data to fool the discriminator network. As such, these systems can be tuned to focus on their generative or discriminative functions. While the latter (discriminator) largely resemble applications of NNs, the former (generative) can provide more efficient and/or accurate solutions to challenges in the methodology of imagery acquisition and analysis. GANs trained on radiographic imagery have been applied in the context of radiotherapy treatment plan generation, prediction of brain tumor growth patterns, and acceleration of image recompilation in an existing picture archiving and communication system. However, the greatest strength may lie in the “quality-of-life” improvements that GANs represent.
GAN-based imagery protocols have captured MR and CT images with reduced scan times, radiation doses, and contrast required. Retrospective GANs can intelligently denoise low quality imagery and correct for motion artifacts. A fascinating application of GAN involves intermodality conversion of imaging—MRI to CT, CT to MRI, and CT to cbCT. This functionality may enable the surgeon and the physician to benefit from the diagnostic insight of either modality while reducing costs to the patient or minimizing radiation dose. As such, although GAN methods are still in their infancy, successful implementation will dramatically improve the medical imagery workflow.
4 figures, 1 table
3. Ren J, Jiang N, Bian L, et al. Natural history of spinal cord cavernous malformations: A multicenter cohort study. Neurosurgery 2022;90:390–98. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/35049523/
Compared with their intracranial counterparts, spinal cord CMs (SCCMs) are more aggressive because of greater vulnerability of the tightly compacted eloquent cord structures within the narrow confine of the spinal canal. However, relatively little data exist on the natural history of SCCMs because of their rarity. Previous studies have suggested that the annual hemorrhagic rates of SCCMs ranged from 1.4% to 6.8%. All patients between 2002 and 2019 with diagnosis of SCCMs were identified retrospectively. An observational study of patients with conservative management was performed to reveal the natural history of SCCMs. The authors identified 305 patients in the full cohort, including 126 patients who were conservatively treated for at least 6 months (median observational period, 24.0 months). Forty-five hemorrhage events occurred during 527 person-years of follow-up, yielding an annual hemorrhage rate of 8.5% per person-year. The 1-, 2-, and 5-year cumulative risks of hemorrhage were 13.9%, 26.1%, and 35.1%, respectively. Prior hemorrhage and pediatric patients were independent predictors of hemorrhage in the long-term follow-up. Familial form and subsequent hemorrhage events were independent risk factors for worsening of neurologic function, and baseline neurologic status and presence of subsequent hemorrhage were significantly associated with neurologic outcomes.
The natural history of SCCMs is poor, variable, but predictable. Patients with SCCMs can be stratified to predict the future hemorrhage risks and neurologic impairment. Initial baseline characteristics significantly affect the natural history of the SCCMs, which prompts a differentiated treatment strategy.
2 figures, 5 tables, with MR images
4. Beucler N, Dagain A. Historical vignette portraying the difference between the “sinking skin flap syndrome” and the “syndrome of the trephined” in decompressive craniectomy. World Neurosurg [Internet]. 2022;162:11–14. Available from: https://doi.org/10.1016/j.wneu.2022.03.027
Decompressive craniectomy has been adopted as a possible therapeutic option for extreme cases of traumatic brain injury and malignant ischemic stroke. The history of decompressive craniectomy, though, involves civilian and military discoveries that have been progressively confused and even forgotten according to the authors. The syndrome of the trephined was introduced in 1939 as a feeling of tenderness, discomfort, and insecurity located at the site of craniectomy. Forty years later, in 1977, the sinking skin flap syndrome was defined as new-onset neurologic deficits or even coma associated with marked skin depression at the site of craniectomy, indicating urgent need for cranioplasty. These 2 syndromes illustrate the paradigm shift of the indications for cranioplasty, which have evolved from cosmetic reasons in the 1940s to cerebral metabolism improvement in the early 21st century.
The authors would like to raise the neurosurgical community’s awareness regarding SSFS, which is a rare, poorly known, and incompletely understood yet serious complication that can occur if cranioplasty if performed in a delayed fashion. SSFS is a neurosurgical emergency, the treatment of which involves Trendelenburg positioning until urgent cranioplasty can be performed. In contrast, the so-called ST can be described as the association of pain, discomfort, and a feeling of insecurity at the site of craniectomy, and should be clearly distinguished from SSFS.
1 table
5. Abecassis IJ, Meyer RM, Levitt MR, et al. Recurrence after cure in cranial dural arteriovenous fistulas: A collaborative effort by the Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR). J Neurosurg 2021;136:1–9. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/34507283/
Cranial dural arteriovenous fistulas (dAVFs) are often treated with endovascular therapy, but occasionally a multimodality approach including surgery and/or radiosurgery is utilized. Recurrence after an initial angiographic cure has been reported, with estimated rates ranging from 2% to 14.3%, but few risk factors have been identified. The objective of this study was to identify risk factors associated with recurrence of dAVF after putative cure.
Of the 1077 patients included in the primary CONDOR data set, 457 met inclusion criteria. A total of 32 patients (7%) experienced 34 events of recurrence at a mean of 368.7 days (median 192 days). The recurrence rate was 4.5% overall. Kaplan-Meier analysis predicted long-term recurrence rates approaching 11% at 3 years. Grade III dAVFs treated with endovascular therapy were statistically significantly more likely to experience recurrence than those treated surgically (13.3% vs 0%). Tentorial location, cortical venous drainage, and deep cerebral venous drainage were all risk factors for recurrence. Endovascular intervention and radiosurgery were associated with recurrence. Six recurrences were symptomatic, including 2 with hemorrhage, 3 with nonhemorrhagic neurologic deficit, and 1 with progressive flow-related symptoms (decreased vision).
They conclude that recurrence after initial cure in cranial dAVF occurs at a rate of 4.5% per year. Longer-term projected rates approach 11% at 3 years and 26% at 10 years, though these may be overestimates. Recurrence was only seen after endovascular embolization as the first treatment modality, particularly in Borden type III lesions, but this probably reflects patient selection and frequency of treatment, as microsurgical ligation was seldom used in Borden type I and II dAVFs. Tentorial location, CVD, and deep venous drainage are risk factors for recurrence. Long-term follow-up is important in patients with “cured” dAVFs, even beyond a year from cure, to ensure a durable result and prevent subsequent hemorrhage.
3 figures, 5 tables, no imaging
6. Xiong GX, Fisher MWA, Schwab JH, et al. A natural history of patients treated operatively and nonoperatively for spinal metastases over 2 years following treatment. Spine (Phila Pa 1976) 2022;47:515–22. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/35066537/
There have been many different scoring systems proposed regarding predicting survival with spinal metastatic disease…SORG nomogram, Tokuhashi, revised Tokuhashi, Tomita, Bauer, Modified Bauer, Katagiri, and Linden, to name a few. In this one, the New England Spinal Metastasis Score is utilized. The NESMS accounts for primary tumor characteristics and metastatic burden at baseline using the modified Bauer score and also incorporates general health and functional status via serum albumin and ambulatory capacity. Analyses using the NESMS relied on a score of 3 (the best possible score in the system).
Surgical treatment has been touted to preserve functional independence, quality of life, and survival. Nearly all prior investigations have been limited by retrospective design and relatively short periods of posttreatment surveillance. The authors recently completed the Prospective Observational study of Spinal metastasis Treatment (POST), which was originally designed to examine aspects of the New England Spinal Metastasis Score and its prognostic capacity in the setting of spinal metastatic disease. The objective of this work was to present the natural history, including ultimate survival and functional outcomes, among the patients who participated in the POST study (202 patients enrolled).
They found that, while patients treated operatively and nonoperatively both benefitted from treatment in terms of improvement in HRQL measures, the mortality rate was sobering across both cohorts. They encountered close to 50% mortality at 1 year and 70% mortality by 2 years, with no significant differences in mortality rates between the operative and nonoperative groups at any time point. In Cox regression analyses, the most influential factors were low NESMS at presentation (scores of 0 and 1). There was a trend toward increased mortality for a NESMS score of 2 but this factor did not reach significance (P=.08).
They conclude that there was no appreciable survival advantage, overall, for those patients who received surgery. This supports the notion that surgical intervention is best reserved for those individuals who otherwise can derive demonstrable benefits in terms of quality of life, maintenance of ambulatory or neurologic function, and pain reduction. When prognosticating longitudinal survival, the NESMS appears to be an effective utility, particularly among patients with scores of 0 or 1.
3 tables
7. Mittal S, Ahuja K, Sudhakar PV, et al. Simultaneous decompression of all stenotic regions versus decompression of only the most symptomatic region in patients with tandem spinal stenosis: A systematic review and meta-analysis. Eur Spine J [Internet] 2022;31:561–74. Available from: https://doi.org/10.1007/s00586-021-07078-7
Selection of anatomic region of spine for decompression in patients with symptomatic tandem spinal stenosis (TSS) remains a challenge due to the confusing clinical presentation as well as uncertain evidence. A systematic review and meta-analysis of observational studies were conducted to compare the outcomes between simultaneous decompression of all stenotic regions (cervical and lumbar, Group 1) and decompression of only the most symptomatic stenotic region (cervical/lumbar, Group 2) in patients with TSS.
Ten studies were included in the analysis out of which all were retrospective observational studies (Level 4 evidence) except 1 (Level 3 evidence). Overall proportional meta-analysis showed no significant difference in change in JOA scores, operative time, blood loss, total and major complications between Group 1 and Group 2. However, minor complications were significantly increased on performing decompression of both regions simultaneously.
Decompression of the most symptomatic region alone irrespective of its location has equal clinical outcomes with less complication rate than simultaneous decompression in patients with TSS.
4 tables, 5 figures
8. Kanna RM, Hajare S, Thippeswamy PB, et al. Advanced disc degeneration, bi-planar instability and pathways of peri-discal gas suffusion contribute to pathogenesis of intradiscal vacuum phenomenon. Eur Spine J [Internet] 2022;31:755–63. Available from: https://doi.org/10.1007/s00586-022-07122-0
IDVP (aka “vacuum phenomenon”) is a radiologic (x-ray, CT or MRI) observation of gas accumulation within the disc cleft. It consists of predominantly nitrogen (90%), along with carbon dioxide, oxygen, and other trace gases. The first description of gas within a joint was by Fick in 1910 while studying joints under traction. The term “vacuum phenomenon” was coined by Magnusson in 1937 while Knutsson correlated the presence of VP with disc degeneration in 1942. With its increasing recognition, 2 interrelated theories were postulated for the development of IDVP: “negative pressure theory” and “endplate degeneration theory.” The negative pressure theory states that constant extension and distraction of the spine create micromotion between adjacent vertebrae. With advanced degeneration of the nucleus pulposus, the cavity expands with this micromotion and consequently the pressure in the cavity decreases. This allows gases such as nitrogen with low solubility to leave the solution and collect within the cavity. The endplate degeneration theory was proposed by Li, et al, which states that endplate degeneration is the origin of VP. Endplate calcification blocks the transfer of nutrients and metabolites to the inner disc, leading to disc degeneration and entrapment of gases.
The authors identified that along with disc degeneration, there are 2 other essential factors in the pathogenesis of IDVP—the presence of pathways of peri-discal gases to suffuse into the disc, and the presence of angular instability to generate negative suction forces within the disc.
They observed 3 potential pathways for the transfer of gases: anterior longitudinal ligament, vertebral endplate, and lateral annulus. The presence of disruption of ALL was significantly higher in discs with IDVP (30.3% vs 2.1%). This was typically seen in the midsagittal sections of T1 MR images. Coronal translation of the spine in the AP radiographs indicating lateral annulus insufficiency was also 7 times more commonly noted in discs with IDVP. A disrupted ALL and coronal translation as a pathogenetic contributor of IDVP has not been previously studied in the literature. Also, it was observed that Modic changes were strongly associated with IDVP (88%) vs 17.4% in non-IDVP discs. Endplate damage may allow the transfer of gases into the disc with repetitive micromotion. The association of Modic changes and IDVP has been supported by other authors as well. Thus, disruption of 1 of these structures, the ALL, lateral annulus, and vertebral endplate, could provide pathways for the transfer of gases into the degenerated disc.
4 tables, 5 figures…lots of plain radiographs
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