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C. Michael Honey, Zurab Ivanishvili, Christopher R. Honey and Manraj K. S. Heran

OBJECTIVE

The location of the human spinothalamic tract (STT) in the anterolateral spinal cord has been known for more than a century. The exact nature of the neuronal fiber lamination within the STT, however, remains controversial. After correlating in vivo macrostimulation-induced pain/temperature sensation during percutaneous cervical cordotomy with simultaneous CT imaging of the electrode tip location, the authors present a modern description of the somatotopy of the human cervical STT.

METHODS

Twenty patients underwent CT-guided percutaneous cervical cordotomy to alleviate contralateral medication-refractory cancer pain. Patient responses to electrical stimulation (0.01–0.1 V, 50 Hz, 1 msec) were recorded and the electrode location for each response was documented with a contemporaneous CT scan. In a post hoc analysis of the data, the location for each patient’s response(s) was measured and drawn on a diagram of their cord. Positive responses were represented only when the lowest possible voltage (≤ 0.02 V) elicited a response. Negative responses were recorded if there was no clinical response at 0.1 V.

RESULTS

Clinically, patients did well with an average reduction in opiates of 75% at 1 week, and 67% were able to leave the palliative care unit. The size of the cervical cord varied between patients, with an average lateral extent (width) of 11 mm and a height of 9 mm. Responses from the lower limb were represented superficially (lateral) and posteriorly within the anterolateral cord. The area with responses from the upper limb was larger and surrounded those with responses from the lower limb primarily anteriorly and medially, but also posteriorly.

CONCLUSIONS

In this study, the somatotopic organization of the human STT was elucidated for the first time using in vivo macrostimulation and contemporaneous CT imaging during cordotomy. In this cohort of patients, the STT from the lower-limb region was located superficially and posteriorly in the anterolateral quadrant of the cervical cord, with the STT from the upper-limb region surrounding it primarily anteriorly and medially (deep) but also posteriorly. The authors discuss how the previous methods of cordotomy may have biased the earlier versions of STT lamination. They suggest that an ideal spinal cord entry site for cordotomy of either the upper- or lower-limb pain fibers is halfway between the equator and anterior pole of the cord.

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Francis Lovecchio, Jeffrey G. Stepan, Ajay Premkumar, Michael E. Steinhaus, Maria Sava, Peter Derman, Han Jo Kim and Todd Albert

OBJECTIVE

Patients with lumbar spine pathology are at high risk for opioid misuse. Standardizing prescribing practices through an institutional intervention may reduce the overprescribing of opiates, leading to a decrease in the risk for opioid misuse and the number of pills available for diversion. Without quantitative data on the “minimum necessary quantity” of opioids appropriate for postdischarge prescriptions, the optimal method for changing existing prescribing practices is unknown. The purpose of this study was to determine whether mandatory provider education and prescribing guidelines could modify prescriber behavior and lead to a decreased amount of opioids prescribed at hospital discharge following lumbar spine surgery.

METHODS

Qualified staff were required to attend a mandatory educational conference, and a consensus method among the spine service was used to publish qualitative prescribing guidelines. Prescription data for 2479 patients who had undergone lumbar spine surgery were captured and compared based on the timing of surgery. The preintervention group consisted of 1177 patients who had undergone spine surgery in the period before prescriber education and guidelines (March 1, 2016–November 1, 2016). The postintervention group consisted of 1302 patients who had undergone spine surgery after the dissemination of the guidelines (February 1, 2017–October 1, 2017). Surgeries were classified as decompression or fusion procedures. Patients who had undergone surgeries for infection and patients on long-acting opioids were excluded.

RESULTS

For all lumbar spine surgeries (decompression and fusion), the mean amount of opioids prescribed at discharge was lower after the educational program and distribution of prescribing guidelines (629 ± 294 oral morphine equivalent [OME] preintervention vs 490 ± 245 OME postintervention, p < 0.001). The mean number of prescribed pills also decreased (81 ± 26 vs 66 ± 22, p < 0.001). Prescriptions for 81 or more tablets dropped from 65.5% to 25.5%. Tramadol was prescribed more frequently after prescriber education (9.9% vs 18.6%, p < 0.001). Refill rates within 6 weeks were higher after the institutional intervention (7.6% vs 12.4%, p < 0.07).

CONCLUSIONS

Qualitative guidelines and prescriber education are effective in reducing the amount of opioids prescribed at discharge and encouraging the use of weaker opioids. Coupling provider education with prescribing guidelines is likely synergistic in achieving larger reductions. The sustainability of these changes is yet to be determined.

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Hongzhou Duan, Dapeng Mo, Yang Zhang, Jiayong Zhang and Liang Li

OBJECTIVE

Symptomatic steno-occlusion of the proximal vertebral artery (VA) or subclavian artery (ScA) heralds a poor prognosis and high risk of stroke recurrence despite medical therapy, including antiplatelet or anticoagulant drugs. In some cases, the V2 segment of the cervical VA is patent and perfused via collateral vessels. The authors describe 7 patients who were successfully treated by external carotid artery (ECA)–saphenous vein (SV)–VA bypass.

METHODS

Seven cases involving symptomatic patients were retrospectively studied: 3 cases of V1 segment occlusion, 2 cases of severe in-stent restenosis in the V1 segment, and 2 cases of occlusion of the proximal ScA. All patients underwent ECA-SV-VA bypass. The ECA was isolated and retracted, and the anterior wall of the transverse foramen was unroofed. The VA was exposed, and then the 2 ends of the SV were anastomosed to the VA and ECA in an end-to-side fashion.

RESULTS

Surgical procedures were all performed as planned, with no intraoperative complications. There were 2 postoperative complications (severe laryngeal edema in one case and shoulder weakness in another), but both patients recovered fully and measures were taken to minimize laryngeal edema and its effects in subsequent cases. All patients experienced improvement of their symptoms. No new neurological deficits were reported. Postoperative angiography demonstrated that the anastomoses were all patent, and analysis of follow-up data (range of follow-up 12–78 months) revealed no further ischemic events in the vertebrobasilar territory.

CONCLUSIONS

The ECA-SV-VA bypass is a useful treatment for patients who suffer medically refractory ischemic events in the vertebrobasilar territory when the proximal part of the VA or ScA is severely stenosed or occluded but the V2 segment of the cervical VA is patent.

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Timothy G. White, Hussam Abou-Al-Shaar, Jung Park, Jeffrey Katz, David J. Langer and Amir R. Dehdashti

OBJECTIVE

Cerebral revascularization for carotid occlusion was previously a mainstay procedure for the cerebrovascular neurosurgeon. However, the 1985 extracranial-intracranial bypass trial and subsequently the Carotid Occlusion Surgery Study (COSS) provided level 1 evidence via randomized controlled trials against bypass for symptomatic atherosclerotic carotid occlusion disease. However, in a small number of patients optimal medical therapy fails, and some patients with flow-limiting stenosis develop a perfusion-dependent neurological examination. Therefore it is necessary to further stratify patients by risk to determine who may most benefit from this intervention as well as to determine perioperative morbidity in this high-risk patient population.

METHODS

A retrospective review was performed of all revascularization procedures done for symptomatic atherosclerotic cerebrovascular steno-occlusive disease. All patients undergoing revascularization after the publication of the COSS in 2011 were included. Perioperative morbidity and mortality were assessed as the primary outcome to determine safety of revascularization in this high-risk population. All patients had documented hypoperfusion on hemodynamic imaging.

RESULTS

At total of 35 revascularization procedures were included in this review. The most common indication was for patients with recurrent strokes, who were receiving optimal medical therapy and who suffered from cerebrovascular steno-occlusion. At 30 days only 3 perioperative ischemic events were observed, 2 of which led to no long-term neurological deficit. Immediate graft patency was good, at 94%. Long term, no further strokes or ischemic events were observed, and graft patency remained high at 95%. There were no factors associated with perioperative ischemic events in the variables that were recorded.

CONCLUSIONS

Cerebral revascularization may be done safely at high-volume cerebrovascular centers in high-risk patients in whom optimal medical therapy has failed. Further research must be done to develop an improved methodology of risk stratification for patients with symptomatic atherosclerotic cerebrovascular steno-occlusive disease to determine which patients may benefit from intervention. Given the high risk of recurrent stroke in certain patients, and the fact that patients fail medical therapy, surgical revascularization may provide the best method to ensure good long-term outcomes with manageable up-front risks.

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Mohamed Somji, James McEachern and Joseph Silvaggio

OBJECTIVE

Cerebral proliferative angiopathy (CPA) is considered a discrete vascular malformation of the brain separate from classical brain arteriovenous malformations (AVMs). It has unique angiographic characteristics and has been hypothesized to result from chronic cortical ischemia and perinidal oligemia. Treatment with cerebral revascularization has been proposed in an attempt to disrupt regional hypoperfusion and interrupt the angiogenesis that defines CPA. A systematic review of the literature pertaining to the role of cerebral revascularization may highlight a treatment paradigm for this rare disease.

METHODS

A systematic review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. MEDLINE and Embase were searched from inception for papers relating to CPA. Included articles were categorized according to methodology (case series or imaging study) and treatment modality (conservative, radiation, endovascular, or revascularization). A synthesis was compiled summarizing the current evidence regarding cerebral revascularization in CPA.

RESULTS

The initial search revealed 43 articles, of which 28 studies met the inclusion criteria. Nine studies were identified that described imaging findings, which suggested hemodynamic dysregulation and perinidal impairments in the cerebrovascular reserve could be identified compared to unaffected hemispheres and classical brain AVMs. Six studies including 7 patients undergoing indirect forms of cerebral revascularization were identified. Clinical and radiological outcomes following revascularization were favorable in all but one study.

CONCLUSIONS

A small body of radiological and clinical studies has emerged, suggesting that CPA is a response to perinidal oligemia. While the long-term clinical efficacy of revascularization remains unclear, early results suggest that this may be a novel treatment paradigm for patients with CPA.

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Shunsuke Nomura, Koji Yamaguchi, Tatsuya Ishikawa, Akitsugu Kawashima, Yoshikazu Okada and Takakazu Kawamata

OBJECTIVE

Effectively retaining the patency of the extracranial-intracranial (ECIC) bypass is one of the most important factors in improving long-term results; however, the factors influencing bypass patency have not been discussed much. Therefore, the authors investigated factors influencing the development of the bypass graft.

METHODS

In this retrospective study, the authors evaluated 49 consecutive hemispheres in 47 adult Japanese patients who had undergone ECIC bypass for chronic steno-occlusive cerebrovascular disease. To evaluate objectively the development of the ECIC bypass graft, the change in the area of the main trunk portion of the superficial temporal artery (STA) from before to after bypass surgery (postop/preop STA) was measured. Using the interquartile range (IQR), the authors statistically analyzed the factors associated with excellent (> 3rd quartile) and poor development (< 1st quartile) of the bypass graft.

RESULTS

The postop/preop STA ranged from 1.08 to 6.13 (median 1.97, IQR 1.645–2.445). There was a significant difference in the postop/preop STA between the presence and absence of concurrent diabetes mellitus (p = 0.0432) and hyperlipidemia (0.0069). Furthermore, logistic regression analysis revealed that only concurrent diabetes mellitus was significantly associated with poor development of the bypass graft (p = 0.0235).

CONCLUSIONS

Diabetes mellitus and hyperlipidemia influenced the development of the ECIC bypass graft. In particular, diabetes mellitus is the only factor associated with poor development of the bypass graft.

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Bradley Kolb, Hassan Fadel, Gary Rajah, Hamidreza Saber, Ali Luqman and Leonardo Rangel-Castilla

OBJECTIVE

Steno-occlusive diseases of the cerebral vasculature have been associated with cognitive decline. The authors performed a systematic review of the existing literature on intracranial steno-occlusive disease, including intracranial atherosclerosis and moyamoya disease (MMD), to determine the extent and quality of evidence for the effect of revascularization on cognitive performance.

METHODS

A systematic search of PubMed/MEDLINE, the Thomson Reuters Web of Science Core Collection, and the KCI Korean Journal Database was performed to identify randomized controlled trials (RCTs) in the English-language literature and observational studies that compared cognitive outcomes before and after revascularization in patients with steno-occlusive disease of the intracranial vasculature, from which data were extracted and analyzed.

RESULTS

Nine papers were included, consisting of 2 RCTs and 7 observational cohort studies. Results from 2 randomized trials including 142 patients with symptomatic intracranial atherosclerotic steno-occlusion found no additional benefit to revascularization when added to maximal medical therapy. The certainty in the results of these trials was limited by concerns for bias and indirectness. Results from 7 observational trials including 282 patients found some cognitive benefit for revascularization for symptomatic atherosclerotic steno-occlusion and for steno-occlusion related to MMD in children. The certainty of these conclusions was low to very low, due to both inherent limitations in observational studies for inferring causality and concerns for added risk of bias and indirectness in some studies.

CONCLUSIONS

The effects of revascularization on cognitive performance in intracranial steno-occlusive disease remain uncertain due to limitations in existing studies. More well-designed randomized trials and observational studies are needed to determine if revascularization can arrest or reverse cognitive decline in these patients.

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The evolution of minimally invasive spine surgery

JNSPG 75th Anniversary Invited Review Article

Jang W. Yoon and Michael Y. Wang

The field of minimally invasive spine surgery (MISS) has rapidly evolved over the past 3 decades. This review follows the evolution of techniques and principles that have led to significant advances in the field. While still representing only a subset of spine surgeries, MISS’s goals of reducing soft-tissue trauma and mitigating the morbidity of surgery are being realized, translating into more rapid recovery, lower infection rates, and higher cost savings. Future advances in technology and techniques can be anticipated.

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Sauson Soldozy, John S. Costello, Pedro Norat, Jennifer D. Sokolowski, Kamron Soldozy, Min S. Park, Petr Tvrdik and M. Yashar S. Kalani

While the majority of cerebral revascularization advancements were made in the last century, it is worth noting the humble beginnings of vascular surgery throughout history to appreciate its progression and application to neurovascular pathology in the modern era. Nearly 5000 years of basic human inquiry into the vasculature and its role in neurological disease has resulted in the complex neurosurgical procedures used today to save and improve lives. This paper explores the story of the extracranial-intracranial approach to cerebral revascularization.