Determination of the optimal approach to traumatic atlas fractures with or without transverse atlantal ligament (TAL) injury requires a nuanced understanding of the biomechanics of the atlantoaxial complex. The "rule of Spence" (ROS) was created in 1970 in a landmark effort to streamline management of burst-type atlas fractures. The ROS states that radiographic evidence of lateral mass displacement (LMD) (i.e., the distance that the C1 lateral masses extend beyond the C2 superior articular processes) greater than 6.9 mm may indicate both a torn TAL and need for surgical management. Since then, the ROS has become ubiquitous in the spine literature about atlas injuries. However, in the decades since the original paper by Spence et al., modern research efforts and imaging advancements have revealed that the ROS is inaccurate on both fronts: it neither accurately predicts a TAL injury nor does it inform surgical decision-making. The purpose of this review was to delineate the history of the ROS, demonstrate its limitations, present findings in the existing literature on ROS and LMD thresholds, and discuss the current landscape of management techniques for TAL injuries, including parameters such as the atlantodental interval and type of injury according to the Dickman classification system and AO Spine upper cervical injury classification system. The ROS was revolutionary for initially investigating and later propelling the biomechanical and clinical understanding of atlas fractures and TAL injuries; however, it is time to retire its legacy as a rule.
Srujan Kopparapu, Gordon Mao, Brendan F. Judy, and Nicholas Theodore
Carly Weber-Levine, Brendan F. Judy, Andrew M. Hersh, Tolulope Awosika, Yohannes Tsehay, Timothy Kim, Alejandro Chara, and Nicholas Theodore
The authors systematically reviewed current evidence for the utility of mean arterial pressure (MAP), intraspinal pressure (ISP), and spinal cord perfusion pressure (SCPP) as predictors of outcomes after traumatic spinal cord injury (SCI).
PubMed, Cochrane Reviews Library, EMBASE, and Scopus databases were queried in December 2020. Two independent reviewers screened articles using Covidence software. Disagreements were resolved by a third reviewer. The inclusion criteria for articles were 1) available in English; 2) full text; 3) clinical studies on traumatic SCI interventions; 4) involved only human participants; and 5) focused on MAP, ISP, or SCPP. Exclusion criteria were 1) only available in non-English languages; 2) focused only on the brain; 3) described spinal diseases other than SCI; 4) interventions altering parameters other than MAP, ISP, or SCPP; and 5) animal studies. Studies were analyzed qualitatively and grouped into two categories: interventions increasing MAP or interventions decreasing ISP. The Scottish Intercollegiate Guidelines Network level of evidence was used to assess bias and the Grading of Recommendations, Assessment, Development, and Evaluation approach was used to rate confidence in the anticipated effects of each outcome.
A total of 2540 unique articles were identified, of which 72 proceeded to full-text review and 24 were included in analysis. One additional study was included retrospectively. Articles that went through full-text review were excluded if they were a review paper (n = 12), not a full article (n = 12), a duplicate paper (n = 9), not a human study (n = 3), not in English (n = 3), not pertaining to traumatic SCI (n = 3), an improper intervention (n = 3), without intervention (n = 2), and without analysis of intervention (n = 1). Although maintaining optimal MAP levels is the current recommendation for SCI management, the published literature supports maintenance of SCPP as a stronger indicator of favorable outcomes. Studies also suggest that laminectomy and durotomy may provide better outcomes than laminectomy alone, although higher-level studies are needed. Current evidence is inconclusive on the effectiveness of CSF drainage for reducing ISP.
This review demonstrates the importance of assessing how different interventions may vary in their ability to optimize SCPP.
Alexander Perdomo-Pantoja, Hesham Mostafa Zakaria, Brendan F. Judy, Jawad M. Khalifeh, Jose L. Porras, Tej D. Azad, Brian Y. Hwang, Timothy F. Witham, Chetan Bettegowda, and Nicholas Theodore
Intracranial deposits of fat droplets are an unusual presentation of a spinal dermoid cyst after spontaneous rupture and are even more uncommon after trauma. Here, the authors present a case with this rare clinical presentation, along with a systematic review of the literature to guide decision making in these patients.
A 54-year-old woman with Lynch syndrome presented with severe headache and sacrococcygeal pain after a traumatic fall. Computed tomography of the head revealed multifocal intraventricular and intracisternal fat deposits, which were confirmed by magnetic resonance imaging (MRI) of the neuroaxis; in addition, a ruptured multiloculated cyst was identified within the sacral canal with proteinaceous/hemorrhagic debris, most consistent with a sacral dermoid cyst with rupture into the cerebrospinal fluid (CSF) space. An unruptured sacral cyst was later noted on numerous previous MRI scans. In our systematic review, we identified 20 similar cases, most of which favored surgical treatment.
Rupture of an intraspinal dermoid cyst must be considered when intracranial fat deposits are found in the context of cauda equina syndrome, meningism, or hydrocephalus. Complete tumor removal with close postoperative follow-up is recommended to decrease the risk of complications. CSF diversion must be prioritized if life-threatening hydrocephalus is present.
Brendan F. Judy, Hector Soriano-Baron, Yike Jin, Hesham M. Zakaria, Srujan Kopparapu, Mir Hussain, Connor Pratt, and Nicholas Theodore
Navigation and robotics are important tools in the spine surgeon’s armamentarium and use of these tools requires placement of a reference frame. The posterior superior iliac spine (PSIS) is a commonly used site for reference frame placement, due to its location away from the surgical corridor and its ability to provide solid fixation. Placement of a reference frame requires not only familiarity with proper technique, but also command of the relevant anatomy.
Cadaveric analysis demonstrates a significant difference in PSIS location in males versus females, and additionally provides average thickness for accurate placement.
In this technical note, the authors describe the precise technique for PSIS frame placement in addition to relevant anatomy and offer solutions to commonly encountered problems.
Zach Pennington, Brendan F. Judy, Hesham M. Zakaria, Nikita Lakomkin, Anthony L. Mikula, Benjamin D. Elder, and Nicholas Theodore
Spine robots have seen increased utilization over the past half decade with the introduction of multiple new systems. Market research expects this expansion to continue over the next half decade at an annual rate of 20%. However, because of the novelty of these devices, there is limited literature on their learning curves and how they should be integrated into residency curricula. With the present review, the authors aimed to address these two points.
A systematic review of the published English-language literature on PubMed, Ovid, Scopus, and Web of Science was conducted to identify studies describing the learning curve in spine robotics. Included articles described clinical results in patients using one of the following endpoints: operative time, screw placement time, fluoroscopy usage, and instrumentation accuracy. Systems examined included the Mazor series, the ExcelsiusGPS, and the TiRobot. Learning curves were reported in a qualitative synthesis, given as the mean improvement in the endpoint per case performed or screw placed where possible. All studies were level IV case series with a high risk of reporting bias.
Of 1579 unique articles, 97 underwent full-text review and 21 met the inclusion and exclusion criteria; 62 articles were excluded for not presenting primary data for one of the above-described endpoints. Of the 21 articles, 18 noted the presence of a learning curve in spine robots, which ranged from 3 to 30 cases or 15 to 62 screws. Only 12 articles performed regressions of one of the endpoints (most commonly operative time) as a function of screws placed or cases performed. Among these, increasing experience was associated with a 0.24- to 4.6-minute decrease in operative time per case performed. All but one series described the experience of attending surgeons, not residents.
Most studies of learning curves with spine robots have found them to be present, with the most common threshold being 20 to 30 cases performed. Unfortunately, all available evidence is level IV data, limited to case series. Given the ability of residency to allow trainees to safely perform these cases under the supervision of experienced senior surgeons, it is argued that a curriculum should be developed for senior-level residents specializing in spine comprising a minimum of 30 performed cases.
Brendan F. Judy, Jordan W. Swanson, Wuyang Yang, Phillip B. Storm, Scott P. Bartlett, Jesse A. Taylor, Gregory G. Heuer, and Shih-Shan Lang
Evaluation of increased intracranial pressure (ICP) in the pediatric craniosynostosis population based solely on ophthalmological, clinical, and radiographic data is subjective, insensitive, and inconsistent. The aim of this study was to examine the intraoperative ICP before and after craniectomy in this patient population.
The authors measured the ICP before and after craniectomy using a subdural ICP monitor in 45 children. They regulated end-tidal carbon dioxide and the monitoring site under general anesthesia to record consistent ICP readings.
The average age of the patient population was 29 months (range 3.8–180.5 months). Thirty-seven patients (82.2%) were undergoing initial craniosynostosis procedures. All craniosynostosis procedures were categorized as one of the following: frontoorbital advancement (n = 24), frontoorbital advancement with distraction osteogenesis (n = 1), posterior vault distraction osteogenesis (n = 10), and posterior vault reconstruction (n = 10). Nineteen of 45 patients (42.2%) had syndromic or multisuture craniosynostosis. The mean postcraniectomy ICP (8.8 mm Hg, range 2–18 mm Hg) was significantly lower than the precraniectomy ICP (16.5 mm Hg, range 6–35 mm Hg) (p < 0.001). Twenty-four patients (53%) had elevated ICP prior to craniectomy, defined as ≥ 15 mm Hg. Only 4 (8.9%) children had papilledema on preoperative funduscopic examination (sensitivity 17%, specificity 100%, negative predictive value 51%, and positive predictive value 100%). There were no significant differences in elevated precraniectomy ICP based on type of craniosynostosis (syndromic/multisuture or nonsyndromic) or age at the time of surgery. Patients undergoing initial surgery in the first 12 months of life were significantly less likely to have elevated precraniectomy ICP compared with patients older than 12 months (26.3% vs 73.1%, p = 0.005).
In this study, the authors report the largest cohort of syndromic and nonsyndromic craniosynostosis patients (n = 45) who underwent precraniectomy and postcraniectomy ICP evaluation. A craniectomy or completed craniotomy cuts for distractors effectively reduced ICP in 43/45 patients. The authors’ findings support the notion that papilledema on funduscopy is a highly specific, however poorly sensitive, indicator of increased ICP, and thus is not a reliable screening method. These findings indicate that even nonsyndromic patients with craniosynostosis are at risk for increased ICP. Furthermore, patients who present prior to 12 months of age appear less likely to have elevated ICP on presentation. Further studies with other noninvasive imaging of the retina may be useful as an adjunct tool for determining elevated ICP.