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Michael Kern, Matthias Setzer, Lutz Weise, Ali Mroe, Holger Frey, Katharina Frey, Volker Seifert and Stephan Duetzmann

OBJECTIVE

The treatment of patients with spinal stenosis and concurrent degenerative spondylolisthesis is controversial. Two large randomized controlled clinical trials reported contradictory results. The authors hypothesized that a substantial number of patients will show evidence of micro-instability after a sole decompression procedure.

METHODS

This study was a retrospective analysis of all cases of lumbar spinal stenosis treated at the Frankfurt University Clinic (Universitätsklinik Frankfurt) from 2010 through 2013. Patients who had associated spondylolisthesis underwent upright MRI studies in flexion and extension for identification of subtle signs of micro-instability. Clinical outcome was assessed by means of SF-36 bodily pain (BP) and physical functioning (PF) scales.

RESULTS

A total of 21 patients were recruited to undergo upright MRI studies. The mean duration of follow-up was 65 months (SD 16 months). Of these 21 patients, 10 (47%) showed signs of micro-instability as defined by movement of > 4 mm on flexion/extension MRI. Comparison of mean SF-36 BP and PF scores in the group of patients who showed micro-instability versus those who did not showed no statistically significant difference on either scale.

CONCLUSIONS

There seems to be a substantial subset of patients who develop morphological micro-instability after sole decompression procedures but do not experience any clinically significant effect of the instability.

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Da Zou, Weishi Li, Fei Xu and Guohong Du

OBJECTIVE

The aim of this study was to evaluate the use of Hounsfield unit (HU) values of the S1 body to diagnose osteoporosis in patients with lumbar degenerative diseases.

METHODS

The records of 316 patients of ages ≥ 50 years and requiring surgery for lumbar degenerative diseases were reviewed. The bone mineral density (BMD) of the S1 body and L1 was measured in HU with preoperative lumbar CT. Circular regions of interest (ROIs) were placed on midaxial and midsagittal images of the S1 body. Dual-energy x-ray absorptiometry (DXA) and the criterion of L1 HU ≤ 110 HU were used to diagnose osteoporosis. The area under the receiver operating characteristic curve (AUC) was calculated to assess the use of HUs of the S1 body to diagnose osteoporosis.

RESULTS

The interobserver and intraobserver reliability of measuring HU of the S1 body was excellent with intraclass correlation coefficients over 0.8 (p < 0.001). The correlation between HUs of the S1 body and average T-score of L1–4 was significant with Pearson correlation coefficients ≥ 0.60 (p < 0.001). The AUCs for using HUs of the S1 body to diagnose osteoporosis were 0.86 and 0.88 for axial HU and sagittal HU, respectively (p < 0.001). The HU thresholds with balanced sensitivity and specificity for diagnosing osteoporosis were 202 HU for axial HU (sensitivity: 76%; specificity: 76%) and 185 HU for sagittal HU (sensitivity: 80%; specificity: 80%).

CONCLUSIONS

Both sagittal and axial HUs of the S1 body are useful tools for assessing BMD and diagnosing osteoporosis. Measuring HUs of the S1 body preoperatively from lumbar CT may help with surgical planning for patients with lumbar degenerative diseases.

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Courtney M. Schusse, Kris Smith and Cornelia Drees

OBJECTIVE

Hemispherectomy is a surgical technique that is established as a standard treatment in appropriately selected patients with drug-resistant epilepsy. It has proven to be successful in pediatric patients with unilateral hemispheric lesions but is underutilized in adults. This study retrospectively evaluated the clinical outcomes after hemispherectomy in adult patients with refractory epilepsy.

METHODS

This study examined 6 cases of hemispherectomy in adult patients at Barrow Neurological Institute. In addition, all case series of hemispherectomy in adult patients were identified through a literature review using MEDLINE and PubMed. Case series of patients older than 18 years were included; reports of patients without clear follow-up duration or method of validated seizure outcome quantification were excluded. Seizure outcome was based on the Engel classification.

RESULTS

A total of 90 cases of adult hemispherectomy were identified, including 6 newly added by Barrow Neurological Institute. Sixty-five patients underwent functional hemispherectomy; 25 patients had anatomical hemispherectomy. Length of follow-up ranged from 9 to 456 months. Seizure freedom was achieved in 80% of patients. The overall morbidity rate was low, with 9 patients (10%) having new or additional postoperative speech or language dysfunction, and 19 patients (21%) reporting some worsening of hemiparesis. No patients lost ambulatory or significant functional ability, and 2 patients had objective ambulatory improvement. Among the 41 patients who underwent additional formal neuropsychological testing postoperatively, overall stability or improvement was seen.

CONCLUSIONS

Hemispherectomy is a valuable surgical tool for properly selected adult patients with pre-existing hemiparesis and intractable epilepsy. In published cases, as well as in this series, the procedure has overall been well tolerated without significant morbidity, and the majority of patients have been rendered free of seizures.

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Liang Li, Jiantao Yang, Bengang Qin, Honggang Wang, Yi Yang, Jintao Fang, Gang Chen, Xiaolin Liu, Zhehui Tu and Liqiang Gu

OBJECTIVE

Human acellular nerve allograft applications have increased in clinical practice, but no studies have quantified their influence on reconstruction outcomes for high-level, greater, and mixed nerves, especially the brachial plexus. The authors investigated the functional outcomes of human acellular nerve allograft reconstruction for nerve gaps in patients with brachial plexus injury (BPI) undergoing contralateral C7 (CC7) nerve root transfer to innervate the upper trunk, and they determined the independent predictors of recovery in shoulder abduction and elbow flexion.

METHODS

Forty-five patients with partial or total BPI were eligible for this retrospective study after CC7 nerve root transfer to the upper trunk using human acellular nerve allografts. Deltoid and biceps muscle strength, degree of shoulder abduction and elbow flexion, Semmes-Weinstein monofilament test, and static two-point discrimination (S2PD) were examined according to the modified British Medical Research Council (mBMRC) scoring system, and disabilities of the arm, shoulder, and hand (DASH) were scored to establish the function of the affected upper limb. Meaningful recovery was defined as grades of M3–M5 or S3–S4 based on the scoring system. Subgroup analysis and univariate and multivariate logistic regression analyses were conducted to identify predictors of human acellular nerve allograft reconstruction.

RESULTS

The mean follow-up duration and the mean human acellular nerve allograft length were 48.1 ± 10.1 months and 30.9 ± 5.9 mm, respectively. Deltoid and biceps muscle strength was grade M4 or M3 in 71.1% and 60.0% of patients. Patients in the following groups achieved a higher rate of meaningful recovery in deltoid and biceps strength, as well as lower DASH scores (p < 0.01): age < 20 years and age 20–29 years; allograft lengths ≤ 30 mm; and patients in whom the interval between injury and surgery was < 90 days. The meaningful sensory recovery rate was approximately 70% in the Semmes-Weinstein monofilament test and S2PD. According to univariate and multivariate logistic regression analyses, age, interval between injury and surgery, and allograft length significantly influenced functional outcomes.

CONCLUSIONS

Human acellular nerve allografts offered safe reconstruction for 20- to 50-mm nerve gaps in procedures for CC7 nerve root transfer to repair the upper trunk after BPI. The group in which allograft lengths were ≤ 30 mm achieved better functional outcome than others, and the recommended length of allograft in this procedure was less than 30 mm. Age, interval between injury and surgery, and allograft length were independent predictors of functional outcomes after human acellular nerve allograft reconstruction.

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Ryan A. Gellner, Eamon T. Campolettano, Eric P. Smith and Steven Rowson

OBJECTIVE

Youth football attracts approximately 3.5 million participants every year, but concern has recently arisen about the long-term effects of experiencing repetitive head accelerations from a young age due to participation in football. The objective of this study was to quantify total involvement in high-magnitude impacts among individual players in youth football practices. The authors explored the relationship between the total number of high-magnitude accelerations in which players were involved (experienced either by themselves or by other players) during practices and the number of high-magnitude accelerations players experienced.

METHODS

A local cohort of 94 youth football players (mean age 11.9 ± 1.5, mean body mass 50.3 ± 16.4 kg) from 4 different teams were recruited and outfitted with helmet-mounted accelerometer arrays. The teams were followed for one season each for a total of 128 sessions (practices, games, and scrimmages). All players involved in high-magnitude (greater than 40g) head accelerations were subsequently identified through analysis of practice film.

RESULTS

Players who experienced more high-magnitude accelerations were more likely to be involved in impacts associated with high-magnitude accelerations in other players. A small subset of 6 players (6%) were collectively involved in 230 (53%) high-magnitude impacts during practice, were involved in but did not experience a high-magnitude acceleration 78 times (21% of the 370 one-sided high-magnitude impacts), and experienced 152 (30%) of the 502 high-magnitude accelerations measured. Quarterbacks/running backs/linebackers were involved in the greatest number of high-magnitude impacts in practice and experienced the greatest number of high-magnitude accelerations. Which team a player was on was an important factor, as one team showed much greater head impact exposure than all others.

CONCLUSIONS

This study showed that targeting the most impact-prone players for individualized interventions could reduce high-magnitude acceleration exposure for entire teams. These data will help to further quantify elevated head acceleration exposure and enable data-driven interventions that modify exposure for individual players and entire teams.

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Chao Li, Shuo Wang, Jiun-Lin Yan, Turid Torheim, Natalie R. Boonzaier, Rohitashwa Sinha, Tomasz Matys, Florian Markowetz and Stephen J. Price

OBJECTIVE

The objective of this study was to characterize the abnormalities revealed by diffusion tensor imaging (DTI) using MR spectroscopy (MRS) and perfusion imaging, and to evaluate the prognostic value of a proposed quantitative measure of tumor invasiveness by combining contrast-enhancing (CE) and DTI abnormalities in patients with glioblastoma.

METHODS

Eighty-four patients with glioblastoma were recruited preoperatively. DTI was decomposed into isotropic (p) and anisotropic (q) components. The relative cerebral blood volume (rCBV) was calculated from the dynamic susceptibility contrast imaging. Values of N-acetylaspartate, myoinositol, choline (Cho), lactate (Lac), and glutamate + glutamine (Glx) were measured from multivoxel MRS and normalized as ratios to creatine (Cr). Tumor regions of interest (ROIs) were manually segmented from the CE T1-weighted (CE-ROI) and DTI-q (q-ROI) maps. Perfusion and metabolic characteristics of these ROIs were measured and compared. The relative invasiveness coefficient (RIC) was calculated as a ratio of the characteristic radii of CE-ROI and q-ROI. The prognostic significance of RIC was tested using Kaplan-Meier and multivariate Cox regression analyses.

RESULTS

The Cho/Cr, Lac/Cr, and Glx/Cr in q-ROI were significantly higher than CE-ROI (p = 0.004, p = 0.005, and p = 0.007, respectively). CE-ROI had significantly higher rCBV values than q-ROI (p < 0.001). A higher RIC was associated with worse survival in a multivariate overall survival (OS) model (hazard ratio [HR] 1.40, 95% confidence interval [CI] 1.06–1.85, p = 0.016) and progression-free survival (PFS) model (HR 1.55, 95% CI 1.16–2.07, p = 0.003). An RIC cutoff value of 0.89 significantly predicted shorter OS (median 384 vs 605 days, p = 0.002) and PFS (median 244 vs 406 days, p = 0.001).

CONCLUSIONS

DTI-q abnormalities displayed higher tumor load and hypoxic signatures compared with CE abnormalities, whereas CE regions potentially represented the tumor proliferation edge. Integrating the extents of invasion visualized by DTI-q and CE images into clinical practice may lead to improved treatment efficacy.

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Ahmed Mansour, Toshiki Endo, Tomoo Inoue, Kenichi Sato, Hidenori Endo, Miki Fujimura and Teiji Tominaga

The authors report the case of a 78-year-old man with a craniocervical junction epidural arteriovenous fistula who presented with subarachnoid hemorrhage from a ruptured anterior spinal artery (ASA) aneurysm. Because endovascular embolization was difficult, a posterolateral approach was chosen and a novel endoscopic fluorescence imaging system was utilized to clip the aneurysm. The fluorescence imaging system provided clear and magnified views of the ventral spinal cord simultaneously with the endoscope-integrated indocyanine green videoangiography, which helped safely obliterate the ASA aneurysm. With the aid of this novel imaging system, surgeons can appreciate and manipulate complex vascular pathologies of the ventral spinal cord through a posterolateral approach, even when the lesion is closely related to the ASA.

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Dil V. Patel, Joon S. Yoo, Brittany E. Haws, Benjamin Khechen, Eric H. Lamoutte, Sailee S. Karmarkar and Kern Singh

OBJECTIVE

In a large, consecutive series of patients treated with anterior cervical discectomy and fusion (ACDF) performed by a single surgeon, the authors compared the clinical and surgical outcomes of patients who underwent ACDF in an inpatient versus outpatient setting.

METHODS

Patients undergoing primary ACDF were retrospectively reviewed and stratified by surgical setting: hospital or ambulatory surgical center (ASC). Data regarding perioperative characteristics, including hospital length of stay and complications, were collected. Neck Disability Index (NDI) and visual analog scale (VAS) scores were used to analyze neck and arm pain in the preoperative period and at 6 weeks, 3 months, 6 months, and 12 months postoperatively. Postoperative outcomes were compared using chi-square analysis and linear regression.

RESULTS

The study included 272 consecutive patients undergoing a primary ACDF, of whom 172 patients underwent surgery at a hospital and 100 patients underwent surgery at an ASC. Patients undergoing ACDF in the hospital setting were older, more likely to be diabetic, and had a higher comorbidity burden. Patients receiving treatment in the ASC were more likely to carry Workers’ Compensation insurance. Patients in the hospital cohort were more likely to have multilevel procedures, had greater blood loss, and experienced a longer length of stay. In the hospital cohort, 48.3% of patients were discharged within 24 hours, while 43.0% were discharged between 24 and 48 hours after admission. Both cohorts had similar VAS pain scores on postoperative day (POD) 0; however, the hospital cohort consumed more narcotics on POD 0. One patient in the ASC cohort had a pretracheal hematoma that was evacuated immediately in the same surgical center. There were 8 cases of dysphagia in the hospital cohort and 3 cases in the ASC cohort, all of which resolved before the 6-month follow-up. Both cohorts demonstrated similar NDI and VAS neck and arm pain scores preoperatively and at every postoperative time point.

CONCLUSIONS

Although patients undergoing ACDF in the hospital setting were older, had a greater comorbidity burden, and underwent surgery on more levels than patients undergoing ACDF at an outpatient center, this study demonstrated comparable surgical and clinical outcomes for both patient groups. Based on the results of this single surgeon’s experience, 1- to 2-level ACDFs may be performed successfully in the outpatient setting in appropriately selected patient populations.

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Chao-Hung Kuo, Timothy M. Blakely, Jeremiah D. Wander, Devapratim Sarma, Jing Wu, Kaitlyn Casimo, Kurt E. Weaver and Jeffrey G. Ojemann

OBJECTIVE

The activation of the sensorimotor cortex as measured by electrocorticographic (ECoG) signals has been correlated with contralateral hand movements in humans, as precisely as the level of individual digits. However, the relationship between individual and multiple synergistic finger movements and the neural signal as detected by ECoG has not been fully explored. The authors used intraoperative high-resolution micro-ECoG (µECoG) on the sensorimotor cortex to link neural signals to finger movements across several context-specific motor tasks.

METHODS

Three neurosurgical patients with cortical lesions over eloquent regions participated. During awake craniotomy, a sensorimotor cortex area of hand movement was localized by high-frequency responses measured by an 8 × 8 µECoG grid of 3-mm interelectrode spacing. Patients performed a flexion movement of the thumb or index finger, or a pinch movement of both, based on a visual cue. High-gamma (HG; 70–230 Hz) filtered µECoG was used to identify dominant electrodes associated with thumb and index movement. Hand movements were recorded by a dataglove simultaneously with µECoG recording.

RESULTS

In all 3 patients, the electrodes controlling thumb and index finger movements were identifiable approximately 3–6-mm apart by the HG-filtered µECoG signal. For HG power of cortical activation measured with µECoG, the thumb and index signals in the pinch movement were similar to those observed during thumb-only and index-only movement, respectively (all p > 0.05). Index finger movements, measured by the dataglove joint angles, were similar in both the index-only and pinch movements (p > 0.05). However, despite similar activation across the conditions, markedly decreased thumb movement was observed in pinch relative to independent thumb-only movement (all p < 0.05).

CONCLUSIONS

HG-filtered µECoG signals effectively identify dominant regions associated with thumb and index finger movement. For pinch, the µECoG signal comprises a combination of the signals from individual thumb and index movements. However, while the relationship between the index finger joint angle and HG-filtered signal remains consistent between conditions, there is not a fixed relationship for thumb movement. Although the HG-filtered µECoG signal is similar in both thumb-only and pinch conditions, the actual thumb movement is markedly smaller in the pinch condition than in the thumb-only condition. This implies a nonlinear relationship between the cortical signal and the motor output for some, but importantly not all, movement types. This analysis provides insight into the tuning of the motor cortex toward specific types of motor behaviors.

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Vivien Chan, Alessandro Marro, Jeremy Rempel and Andrew Nataraj

OBJECTIVE

In this study the authors sought to compare the proportion of patients with lumbar spondylolisthesis detected to have dynamic instability based on flexion and extension standing radiographs versus neutral standing radiograph and supine MRI.

METHODS

This was a single-center retrospective study of all consecutive adult patients diagnosed with spondylolisthesis from January 1, 2013, to July 31, 2018, for whom the required imaging was available for analysis. Two independent observers measured the amount of translation, in millimeters, on supine MRI and flexion, extension, and neutral standing radiographs using the Meyerding technique. Interobserver and intraobserver correlation coefficients were calculated. The difference in amount of translation was compared between 1) flexion and extension standing radiographs and 2) neutral standing radiograph and supine MRI. The proportion of patients with dynamic instability, defined as a ≥ 3 mm difference in the amount of translation measured on different imaging modalities, was reported. Correlation between amount of dynamic instability and change in back pain and leg pain 1 year after decompression and instrumented fusion was analyzed using multivariate regression analysis.

RESULTS

Fifty-six patients were included in this study. The mean patient age was 57.1 years, and 55.4% of patients were female. The most commonly affected levels were L4–5 (60.7%) and L5–S1 (30.4%). The average translations measured on flexion standing radiograph, extension standing radiograph, neutral standing radiograph, and supine MRI were 12.5 mm, 11.9 mm, 10.1 mm, and 7.2 mm, respectively. The average difference between flexion and extension standing radiographs was 0.58 mm, with dynamic instability detected in 21.4% of patients. The average difference between neutral standing radiograph and supine MRI was 3.77 mm, with dynamic instability detected in 60.7% of patients. The intraobserver correlation coefficient ranged from 0.77 to 0.90 mm. The interobserver correlation coefficient ranged from 0.79 to 0.86 mm. In 44 patients who underwent decompression and instrumented fusion, the amount of dynamic instability between standing and supine imaging was significantly correlated with change in back pain (p < 0.001) and leg pain (p = 0.05) at the 12-month postoperative follow-up. There was no correlation between amount of dynamic instability between flexion and extension standing radiographs and postoperative back pain and leg pain.

CONCLUSIONS

More patients were found to have dynamic instability by using neutral standing radiograph and supine MRI. In patients who received decompression and instrumented fusion, there was a significant correlation between dynamic instability on neutral standing radiograph and supine MRI and change in back pain and leg pain at 12 months.