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Omer Doron, Ofer Barnea, Nino Stocchetti, Tal Or, Erez Nossek and Guy Rosenthal

OBJECTIVE

Previous studies have demonstrated the importance of intracranial elastance; however, methodological difficulties have limited widespread clinical use. Measuring elastance may offer potential benefit in helping to identify patients at risk for untoward intracranial pressure (ICP) elevation from small rises in intracranial volume. The authors sought to develop an easily used method that accounts for the changing ICP that occurs over a cardiac cycle and to assess this method in a large-animal model over a broad range of ICPs.

METHODS

The authors used their previously described cardiac-gated intracranial balloon pump and swine model of cerebral edema. In the present experiment they measured elastance at 4 points along the cardiac cycle—early systole, peak systole, mid-diastole, and end diastole—by using rapid balloon inflation to 1 ml over an ICP range of 10–30 mm Hg.

RESULTS

The authors studied 7 swine with increasing cerebral edema. Intracranial elastance rose progressively with increasing ICP. Peak-systolic and end-diastolic elastance demonstrated the most consistent rise in elastance as ICP increased. Cardiac-gated elastance measurements had markedly lower variance within swine compared with non–cardiac-gated measures. The slope of the ICP–elastance curve differed between swine. At ICP between 20 and 25 mm Hg, elastance varied between 8.7 and 15.8 mm Hg/ml, indicating that ICP alone cannot accurately predict intracranial elastance.

CONCLUSIONS

Measuring intracranial elastance in a cardiac-gated manner is feasible and may offer an improved precision of measure. The authors’ preliminary data suggest that because elastance values may vary at similar ICP levels, ICP alone may not necessarily best reflect the state of intracranial volume reserve capacity. Paired ICP–elastance measurements may offer benefit as an adjunct “early warning monitor” alerting to the risk of untoward ICP elevation in brain-injured patients that is induced by small increases in intracranial volume.

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Sean N. Neifert, Lauren K. Grant, Jonathan J. Rasouli, Ian Thomas McNeill, Samuel K. Cho and John M. Caridi

This report describes a 42-year-old man who presented with an α-type spinal deformity with a Cobb angle of 224.9° and associated spinal cord rotation greater than 90°. Preoperative imaging revealed extensive spinal deformity, and 3D modeling confirmed the α-type nature of his deformity. Intraoperative photography demonstrated spinal cord rotation greater than 90°, which likely contributed to the patient’s poor neurological status. Reports of patients with Cobb angles ≥ 100° are rare, and to the authors’ knowledge, there have been no published cases of adult α-type spinal deformity. Furthermore, very few cases or case series of spinal cord rotation have been published previously, with no single patient having rotation greater than 90° to the authors’ knowledge. Given these two rarities presenting in the same patient, this report can provide important insights into the operative management of this difficult form of spinal deformity.

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Martin J. Rutkowski, Ki-Eun Chang, Tyler Cardinal, Robin Du, Ali R. Tafreshi, Daniel A. Donoho, Andrew Brunswick, Alexander Micko, Chia-Shang J. Liu, Mark S. Shiroishi, John D. Carmichael and Gabriel Zada

OBJECTIVE

Pituitary adenoma (PA) consistency, or texture, is an important intraoperative characteristic that may dictate operative dissection techniques and/or instruments used for tumor removal during endoscopic endonasal approaches (EEAs). The impact of PA consistency on surgical outcomes has yet to be elucidated.

METHODS

The authors developed an objective 5-point grading scale for PA consistency based on intraoperative characteristics, including ease of tumor debulking, manipulation, and instrument selection, ranging from cystic/hemorrhagic tumors (grade 1) to calcified tumors (grade 5). The proposed grading system was prospectively assessed in 306 consecutive patients who underwent an EEA for PAs, and who were subsequently analyzed for associations with surgical outcomes, including extent of resection (EOR) and complication profiles.

RESULTS

Institutional database review identified 306 patients who underwent intraoperative assessment of PA consistency, of which 96% were macroadenomas, 70% had suprasellar extension, and 44% had cavernous sinus invasion (CSI). There were 214 (69.9%) nonfunctional PAs and 92 functional PAs (31.1%). Distribution of scores included 15 grade 1 tumors (4.9%), 112 grade 2 tumors (36.6%), 125 grade 3 tumors (40.8%), 52 grade 4 tumors (17%), and 2 grade 5 tumors (0.7%). Compared to grade 1/2 and grade 3 PAs, grade 4/5 PAs were significantly larger (22.5 vs 26.6 vs 27.4 mm, p < 0.01), more likely to exhibit CSI (39% vs 42% vs 59%, p < 0.05), and trended toward nonfunctionality (67% vs 68% vs 82%, p = 0.086). Although there was no association between PA consistency and preoperative headaches or visual dysfunction, grade 4/5 PAs trended toward preoperative (p = 0.058) and postoperative panhypopituitarism (p = 0.066). Patients with preoperative visual dysfunction experienced greater improvement if they had a grade 1/2 PA (p < 0.05). Intraoperative CSF leaks were noted in 32% of cases and were more common with higher-consistency-grade tumors (p = 0.048), although this difference did not translate to postoperative CSF leaks. Gross-total resection (%) was more likely with lower PA consistency score as follows: grade 1/2 (60%), grade 3 (50%), grade 4/5 (44%; p = 0.045). Extracapsular techniques were almost exclusively performed in grade 4/5 PAs. Assignment of scores showed low variance and high reproducibility, with an intraclass correlation coefficient of 0.905 (95% CI 0.815–0.958), indicating excellent interrater reliability.

CONCLUSIONS

These findings demonstrate clinical validity of the proposed intraoperative grading scale with respect to PA subtype, neuroimaging features, EOR, and endocrine complications. Future studies will assess the relation of PA consistency to preoperative MRI findings to accurately predict consistency, thereby allowing the surgeon to tailor the exposure and prepare for varying resection strategies.

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Alexander Spiessberger, Fabio Strange, Basil Erwin Gruter, Stefan Wanderer, Daniela Casoni, Philipp Gruber, Michael Diepers, Luca Remonda, Javier Fandino, Javier Añon and Serge Marbacher

OBJECTIVE

Temporary parent vessel occlusion performed to establish a high-flow interpositional bypass carries the risk of infarcts. The authors investigated the feasibility of a novel technique to establish a high-flow bypass without temporary parent vessel occlusion in order to lower the risk of ischemic complications.

METHODS

In 10 New Zealand white rabbits, a carotid artery side-to-end anastomosis was performed under parent artery patency with a novel endovascular balloon device. Intraoperative angiography, postoperative neurological assessments, and postoperative MRI/MRA were performed to evaluate the feasibility and safety of the novel technique.

RESULTS

A patent anastomosis was established in 10 of 10 animals; 3 procedure-related complications occurred. No postoperative focal neurological deficits were observed. The MRI/MRA findings include no infarcts and bypass patency in 50% of the animals.

CONCLUSIONS

The authors demonstrated the feasibility of an endovascular assisted, nonocclusive high-flow bypass. Future refinement of the device and technique in an animal model is necessary to lower the complication rate and increase patency rates.

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Andrew L. A. Garton, Connor J. Kinslow and Tony J. C. Wang

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Jaime A. Quirarte, Vinodh A. Kumar, Ho-Ling Liu, Kyle R. Noll, Jeffrey S. Wefel and Frederick F. Lang

Supplementary motor area (SMA) syndrome is well known; however, the mechanism underlying recovery from language SMA syndrome is unclear. Herein the authors report the case of a right-handed woman with speech aphasia following resection of an oligodendroglioma located in the anterior aspect of the left superior frontal gyrus. The patient exhibited language SMA syndrome, and functional MRI (fMRI) findings 12 days postoperatively demonstrated a complete shift of blood oxygen level–dependent (BOLD) activation to the contralateral right language SMA/pre-SMA as well as coequal activation and an increased volume of activation in the left Broca’s area and the right Broca’s homolog. The authors provide, to the best of their knowledge, the first description of dynamic changes in task-based hemispheric language BOLD fMRI activations across the preoperative, immediate postoperative, and more distant postoperative settings associated with the development and subsequent complete resolution of the clinical language SMA syndrome.

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Júlia Miró, Pablo López-Ojeda, Andreu Gabarrós, Javier Urriza, Sedat Ulkatan, Vedran Deletis and Isabel Fernández-Conejero

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Minghao Wang, Praveen V. Mummaneni, Zhuo Xi, Chih-Chang Chang, Joshua Rivera, Jeremy Guinn, Rory Mayer and Dean Chou

OBJECTIVE

A consequence of anterior cervical discectomy and fusion (ACDF) is graft subsidence, potentially leading to kyphosis, nonunion, foraminal stenosis, and recurrent pain. Bone density, as measured in Hounsfield units (HUs) on CT, may be associated with subsidence. The authors evaluated the association between HUs and subsidence rates after ACDF.

METHODS

A retrospective study of patients treated with single-level ACDF at the University of California, San Francisco, from 2008 to 2017 was performed. HU values were measured according to previously published methods. Only patients with preoperative CT, minimum 1-year follow-up, and single-level ACDF were included. Patients with posterior surgery, tumor, infection, trauma, deformity, or osteoporosis treatment were excluded. Changes in segmental height were measured at 1-year follow-up compared with immediate postoperative radiographs. Subsidence was defined as segmental height loss of more than 2 mm.

RESULTS

A total of 91 patients met inclusion criteria. There was no significant difference in age or sex between the subsidence and nonsubsidence groups. Mean HU values in the subsidence group (320.8 ± 23.9, n = 8) were significantly lower than those of the nonsubsidence group (389.1 ± 53.7, n = 83, p < 0.01, t-test). There was a negative correlation between the HU values and segmental height loss (Pearson’s coefficient −0.735, p = 0.01). Using receiver operating characteristic curves, the area under the curve was 0.89, and the most appropriate threshold of HU value was 343.7 (sensitivity 77.1%, specificity 87.5%). A preoperative lower HU is a risk factor for postoperative subsidence (binary logistic regression, p < 0.05). The subsidence rate and distance between allograft and polyetheretherketone (PEEK) materials were not significantly different (PEEK 0.9 ± 0.7 mm, allograft 1.0 ± 0.7 mm; p > 0.05).

CONCLUSIONS

Lower preoperative CT HU values are associated with cage subsidence in single-level ACDF. Preoperative measurement of HUs may be useful in predicting outcomes after ACDF.

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Mark Ren, Barry R. Bryant, Andrew B. Harris, Khaled M. Kebaish, Lee H. Riley III, David B. Cohen, Richard L. Skolasky and Brian J. Neuman

OBJECTIVE

The objectives of the study were to determine, among patients with adult spinal deformity (ASD), the following: 1) how preoperative opioid use, dose, and duration of use are associated with long-term opioid use and dose; 2) how preoperative opioid use is associated with rates of postoperative use from 6 weeks to 2 years; and 3) how postoperative opioid use at 6 months and 1 year is associated with use at 2 years.

METHODS

Using a single-center, longitudinally maintained registry, the authors identified 87 patients who underwent ASD surgery from 2013 to 2017. Fifty-nine patients reported preoperative opioid use (37 high-dose [≥ 90 morphine milligram equivalents daily] and 22 low-dose use). The duration of preoperative use was long-term (≥ 6 months) for 44 patients and short-term for 15. The authors evaluated postoperative opioid use at 6 weeks, 3 months, 6 months, 1 year, and 2 years after surgery. Multivariate logistic regression was used to determine associations of preoperative opioid use, dose, and duration with use at each time point (alpha = 0.05).

RESULTS

The following preoperative factors were associated with opioid use 2 years postoperatively: any opioid use (adjusted odds ratio [aOR] 14, 95% CI 2.5–82), high-dose use (aOR 7.3, 95% CI 1.1–48), and long-term use (aOR 17, 95% CI 2.2–123). All patients who reported high-dose opioid use at the 2-year follow-up examination had also reported preoperative opioid use. Preoperative high-dose use (aOR 247, 95% CI 5.8–10,546) but not long-term use (aOR 4.0, 95% CI 0.18–91) was associated with high-dose use at the 2-year follow-up visit. Compared with patients who reported no preoperative use, those who reported preoperative opioid use had higher rates of use at each postoperative time point (from 94% vs 62% at 6 weeks to 54% vs 7.1% at 2 years) (all p < 0.001). Opioid use at 2 years was independently associated with use at 1 year (aOR 33, 95% CI 6.8–261) but not at 6 months (aOR 4.3, 95% CI 0.95–24).

CONCLUSIONS

Patients’ preoperative opioid use, dose, and duration of use are associated with long-term use after ASD surgery, and a high preoperative dose is also associated with high-dose opioid use at the 2-year follow-up visit. Patients using opioids 1 year after ASD surgery may be at risk for long-term use.