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Orel A. Zaninovich, Mauricio J. Avila, Matthew Kay, Jennifer L. Becker, R. John Hurlbert and Nikolay L. Martirosyan

OBJECTIVE

Diffusion tensor imaging (DTI) is an MRI tool that provides an objective, noninvasive, in vivo assessment of spinal cord injury (SCI). DTI is significantly better at visualizing microstructures than standard MRI sequences. In this imaging modality, the direction and amplitude of the diffusion of water molecules inside tissues is measured, and this diffusion can be measured using a variety of parameters. As a result, the potential clinical application of DTI has been studied in several spinal cord pathologies, including SCI. The aim of this study was to describe the current state of the potential clinical utility of DTI in patients with SCI and the challenges to its use as a tool in clinical practice.

METHODS

A search in the PubMed database was conducted for articles relating to the use of DTI in SCI. The citations of relevant articles were also searched for additional articles.

RESULTS

Among the most common DTI metrics are fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. Changes in these metrics reflect changes in tissue integrity. Several DTI metrics and combinations thereof have demonstrated significant correlations with clinical function both in model species and in humans. Its applications encompass the full spectrum of the clinical assessment of SCI including diagnosis, prognosis, recovery, and efficacy of treatments in both the spinal cord and potentially the brain.

CONCLUSIONS

DTI and its metrics have great potential to become a powerful clinical tool in SCI. However, the current limitations of DTI preclude its use beyond research and into clinical practice. Further studies are needed to significantly improve and resolve these limitations as well as to determine reliable time-specific changes in multiple DTI metrics for this tool to be used accurately and reliably in the clinical setting.

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Hyun Ho Choi, Young Dae Cho, Dong Hyun Yoo, Su Hwan Lee, Eung Koo Yeon, Hyun-Seung Kang, Won-Sang Cho, Jeong Eun Kim and Moon Hee Han

OBJECTIVE

In the presence of symmetric A1 flow, the safety and efficacy of compromising the anterior communicating artery (ACoA) during coil embolization of ACoA aneurysms has yet to be evaluated. Herein, the authors describe their experience, focusing on procedural safety.

METHODS

Between October 2012 and July 2017, 285 ACoA aneurysms with symmetric A1 flows were treated at the authors’ institution by endovascular coil embolization. Clinical and angiographic outcome data were subjected to binary logistic regression analysis.

RESULTS

ACoA compromise was chosen in the treatment of 71 aneurysms (24.9%), which were completely (n = 15) or incompletely (n = 56) compromised. In the remaining 214 lesions, the ACoA was preserved. Although 9 patients (3.2%) experienced procedure-related thromboembolisms (compromised, 4; preserved, 5), all but 1 patient (with ACoA compromise) were asymptomatic. In multivariate analysis, subarachnoid hemorrhage at presentation was the sole independent risk factor for thromboembolism (OR 15.98, p < 0.01), with ACoA compromise being statistically unrelated. In 276 aneurysms (96.8%) with follow-up of > 6 months (mean 20.9 ± 13.1 months, range 6–54 months), recanalization was confirmed in 21 (minor, 15; major, 6). A narrow (≤ 4 mm) saccular neck (p < 0.01) and ACoA compromise (p = 0.04) were independently linked to prevention of recanalization.

CONCLUSIONS

During coil embolization of ACoA aneurysms, the ACoA may be compromised without serious complications if A1 flows are symmetric. This approach may also confer some long-term protection from recanalization, serving as a valid treatment option for such lesions.

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Feng Yan, Gary Rajah, Yuchuan Ding, Yang Hua, Hongqi Zhang, Liqun Jiao, Guilin Li, Ming Ren, Ran Meng, Feng Lin and Xunming Ji

OBJECTIVE

Symptomatic intracranial hypertension can be caused by cerebral venous sinus stenosis (CVSS) and cerebral venous sinus thrombotic (CVST) stenosis, which is usually found in some patients with idiopathic intracranial hypertension (IIH). Recently, at the authors’ center, they utilized intravascular ultrasound (IVUS) as an adjunct to conventional venoplasty or stenting to facilitate diagnosis and accurate stent placement in CVSS.

METHODS

The authors designed a retrospective review of their prospective database of patients who underwent IVUS-guided venous sinus stenting between April 2016 and February 2017. Clinical, radiological, and ophthalmological information was recorded and analyzed. IVUS was performed in 12 patients with IIH (9 with nonthrombotic CVSS, 3 with secondary stenosis combined with CVST) during venoplasty through venous access. The IVUS catheter was used from a proximal location to the site of stenosis. Post-stenting follow-up, including symptomatic improvement, stent patency, and adjacent-site stenosis, was assessed at 1 year.

RESULTS

Thirteen stenotic cerebral sinuses in 12 patients were corrected using IVUS-guided stenting. No technical or neurological complications were encountered. The IVUS images were excellent for the diagnosis of the stenosis, and intraluminal thrombi were clearly visualized by using IVUS in 3 (25%) of the 12 patients. A giant arachnoid granulation was demonstrated in 1 (8.3%) of the 12 patients. Intravenous compartments or septations (2 of 12, 16.7%) and vessel wall thickening (6 of 12, 50%) were also noted. At 1-year follow-up, 10 of 12 patients were clinically symptom-free in our series.

CONCLUSIONS

IVUS is a promising tool with the potential to improve the diagnostic accuracy in IIH, aiding in identification of the types of intracranial venous stenosis, assisting in stent selection, and guiding stent placement. Further study of the utility of IVUS in venous stenting and venous stenosis pathology is warranted.

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Kyohei Kin, Takao Yasuhara, Yousuke Tomita, Michiari Umakoshi, Jun Morimoto and Isao Date

OBJECTIVE

Cervical spondylotic myelopathy (CSM) is one of the most common causes of spinal cord dysfunction. Surgery for CSM is generally effective, but postoperative delirium is a potential complication. Although there have been some studies that investigated postoperative delirium after spine surgery, no useful tool for identifying high-risk patients has been established, and it is unknown if 36-Item Short Form Health Survey (SF-36) scores can predict postoperative delirium. The objective of this study was to evaluate the correlation between preoperative SF-36 scores and postoperative delirium after surgery for CSM.

METHODS

Sixty-seven patients who underwent surgery for CSM at the authors’ institution were enrolled in this study. Medical records of these patients were retrospectively reviewed. Patient background, preoperative laboratory data, preoperative SF-36 scores, the preoperative Japanese Orthopaedic Association (JOA) score for the evaluation of cervical myelopathy, and perioperative factors were selected as potential risk factors for postoperative delirium. These factors were evaluated using univariable and multivariable logistic regression analysis.

RESULTS

Ten patients were diagnosed with postoperative delirium. Univariable analysis revealed that the physical functioning score (p = 0.01), general health perception score (p < 0.01), and vitality score (p < 0.01) of the SF-36 were significantly lower in patients with postoperative delirium than in those without. The total number of medications was significantly higher in the delirium group compared with the no-delirium group (p = 0.02). In contrast, there were no significant differences between the delirium group and the no-delirium group in cervical JOA scores (p = 0.20). Multivariable analysis revealed that a low general health perception score was an independent risk factor for postoperative delirium (p = 0.02; odds ratio 0.810, 95% confidence interval 0.684–0.960).

CONCLUSIONS

Some of the SF-36 scores were significantly lower in patients with postoperative delirium than in those without. In particular, the general health perception score was independently correlated with postoperative delirium. SF-36 scores could help identify patients at high risk for postoperative delirium and aid in the development of prevention strategies.

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David J. Wallace, Naomi L. Sayre, T. Tyler Patterson, Susannah E. Nicholson, Donald Hilton and Ramesh Grandhi

In addition to standard management for the treatment of the acute phase of spinal cord injury (SCI), implementation of novel neuroprotective interventions offers the potential for significant reductions in morbidity and long-term health costs. A better understanding of the systemic changes after SCI could provide insight into mechanisms that lead to secondary injury. An emerging area of research involves the complex interplay of the gut microbiome and the CNS, i.e., a brain–gut axis, or perhaps more appropriately, a CNS–gut axis. This review summarizes the relevant literature relating to the gut microbiome and SCI. Experimental models in stroke and traumatic brain injury demonstrate the bidirectional communication of the CNS to the gut with postinjury dysbiosis, gastrointestinal-associated lymphoid tissue–mediated neuroinflammatory responses, and bacterial-metabolite neurotransmission. Similar findings are being elucidated in SCI as well. Experimental interventions in these areas have shown promise in improving functional outcomes in animal models. This commensal relationship between the human body and its microbiome, particularly the gut microbiome, represents an exciting frontier in experimental medicine.

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Michael C. Jin, Zachary A. Medress, Tej D. Azad, Vanessa M. Doulames and Anand Veeravagu

Recent advances in stem cell biology present significant opportunities to advance clinical applications of stem cell–based therapies for spinal cord injury (SCI). In this review, the authors critically analyze the basic science and translational evidence that supports the use of various stem cell sources, including induced pluripotent stem cells, oligodendrocyte precursor cells, and mesenchymal stem cells. They subsequently explore recent advances in stem cell biology and discuss ongoing clinical translation efforts, including combinatorial strategies utilizing scaffolds, biogels, and growth factors to augment stem cell survival, function, and engraftment. Finally, the authors discuss the evolution of stem cell therapies for SCI by providing an overview of completed (n = 18) and ongoing (n = 9) clinical trials.

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Shiro Horisawa, Takashi Arai, Naoki Suzuki, Takakazu Kawamata and Takaomi Taira

Cerebellar neuromodulation could influence the pathological abnormalities of movement disorders through several connections between the cerebellum and the basal ganglia or other cortices. In the present report, the authors demonstrate the effects of cerebellar deep brain stimulation (DBS) on a patient with severe generalized fixed dystonia (FD) that was refractory to bilateral pallidotomy and intrathecal baclofen therapy. A previously healthy 16-year-old girl presented with generalized FD. Bilateral pallidotomy and intrathecal baclofen therapy had failed to resolve her condition, following which she received DBS through the bilateral superior cerebellar peduncle (SCP) and dentate nucleus (DN). Ipsilateral stimulation of the SCP or DN improved the FD, and the ability of DBS administered via the SCP to relax muscles was better than that of DN DBS. A considerable improvement of generalized FD, from a bedridden state to a wheelchair-bound state, was observed in the patient following 6 months of chronic bilateral DBS via the SCP; moreover, the patient was able to move her arms and legs. The findings in the present case suggest that neuromodulation of deep cerebellar structures is a promising treatment for FD that is refractory to conventional treatments.

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Vibhu K. Viswanathan, Amy J. Minnema, Stephanus Viljoen and H. Francis Farhadi

Sublaminar implants that encircle cortical bone are well-established adjuncts to pedicle screw-rod constructs in pediatric deformity surgery. Sublaminar bands (SLBs) in particular carry the advantage of relatively greater bone contact surface area as compared to wires and pullout loads that are independent of bone mineral density, in contrast to pedicle screws. Whereas the relevant technical considerations have been reported for pediatric deformity correction, an understanding of the relative procedural specifics of these techniques is missing for adult spinal deformity (ASD), despite several case series that have used distinct posterior tethering techniques for proximal junctional kyphosis prevention. In this paper, the authors summarize the relevant literature and describe a novel technique wherein bilateral tensioned SLBs are introduced at the nonfused proximal junctional level of long-segment ASD constructs.

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Luke G. F. Smith, Nguyen Hoang, Ammar Shaikhouni and Stephanus Viljoen

Pedicle and lateral mass screws are the most common means of rigid fixation in posterior cervical spine fusions. Various other techniques such as translaminar screw placement, paravertebral foramen screw fixation, sublaminar and spinous process wiring, cement augmentation, and others have been developed for primary fixation or as salvage methods. Use of these techniques can be limited by a prior history of osteotomies, poor bone density, destruction of the bone-screw interface, and unfavorable vascular and osseous anatomy.

Here, the authors report on the novel application of cervical sublaminar polyester bands as an adjunct salvage method or additional fixation point used with traditional methods in the revision of prior constructs. While sublaminar polyester bands have been used for decades in pediatric scoliosis surgery in the thoracolumbar spine, they have yet to be utilized as a method of fixation in the cervical spine. In both cases described here, sublaminar banding proved crucial for fixation points where traditional fixation techniques would have been less than ideal. Further study is required to determine the full application of sublaminar polyester bands in the cervical spine as well as its outcomes.

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Surgery for nerve injury: current and future perspectives

JNSPG 75th Anniversary Invited Review Article

Rajiv Midha and Joey Grochmal

In Brief

The authors conducted a brief historical review of nerve repair methods over the past 100 years, with a more detailed review and account on how the advent of nerve transfer procedures in the past 2 decades are improving outcomes in patients with nerve injuries. The paper offers the authors' expert perspective on contemporary practice of nerve surgery for nerve injury repair, in addition to recent exciting innovations and evolution in surgical management.