Spinal Cord Blood Supply and Its Surgical Implications

Diagnosis and Management of Thoracic Myelopathy

Thoracic myelopathy can be a challenging condition to diagnose and treat. Successful outcomes depend on early recondition of the pathology and appropriate surgical referral in cases of progressive neurologic deterioration. The thoracic cord is tethered in kyphosis by the dentate ligaments and contains a tenuous blood supply. These conditions make the thoracic cord particularly susceptible to external compression and ischemic damage. Careful preoperative planning with specific attention to the location and source of thoracic stenosis is critical to successful decompression and complication avoidance. The purpose of this discussion is to outline the common sources of thoracic myelopathy and current recommendations regarding diagnosis and management. The review concludes with an overview of the most up-to-date literature regarding clinical outcomes.

HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP): Case based discussion of risk factors, clinical, and therapeutic considerations

HTLV-1 is a retrovirus virus that infects CD4+ T cells. Most people with HTLV-1 infection remain asymptomatic but some may develop conditions such as HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) or adult T-cell leukemia/lymphoma. HAM/TSP is characterized by progressive spasticity and weakness of the lower extremities, as well as loss of bladder control and sensory disturbances. The risk of developing HAM/TSP is associated with the duration of infection and the proviral load. There is currently no cure for the disease but medications can help manage symptoms and slow the progression of the disease. This is the case of a 66-year-old female who presented with nonspecific symptoms of weakness and spasticity in a hospital in Connecticut and was subsequently diagnosed with HAM/TSP. The patient's diagnosis highlights the importance of considering diseases previously confined to specific endemic regions in a globalized world where increased emigration and population mixing can occur. Early identification and management of such cases is essential for optimizing patient outcomes and quality of life.

False lumen-dependent segmental arteries are associated with spinal cord injury in frozen elephant trunk procedure for acute type I aortic dissection

Objective

To investigate the association between false lumen (FL) dependency of segmental arteries (SAs) at T9-L3 levels and the risk of spinal cord injury (SCI) following total arch replacement and frozen elephant trunk (FET) implantation in the setting of acute DeBakey type I aortic dissection (AAD).

Methods

The study involved consecutive patients with AAD who underwent total arch replacement and FET implantation between 2020 and 2022. Primary outcome was postoperative SCI. The inverse probability of treatment weighting (IPTW) method was employed to minimize the impact of no-randomization bias. Antegrade placement of FET was followed by end-to-end anastomosis of a 4-branch arch graft at the proximal landing site of FET.

Results

A total of 146 patients were included (age, 50.5 ± 11.7 years, 115 male), of whom 35 (24%) had SAs at T9-L3 levels completely dependent on FL (FL-dependency group). There was no significant difference in early (30-day or in-hospital) mortality rates between FL-dependency (14.3%) and FL-independency (18.0%) groups (P = .80), however, the rate of SCI was significantly higher in the FL-Dependency group (34.3% vs 2.7%, P < .001). After adjustments, FL dependency was associated with a significantly increased risk of SCI (odds ratio, 13.1; 95% confidence interval, 4.2-41.0; P < .001), whereas it was not significantly associated with risks of early mortality or other major complications (P = .16-.98).

Conclusions

FL dependency of SAs at the T9-L3 levels was significantly associated with the development of SCI following FET implantation in AAD, warning against its uses on patients presenting with FL dependency of SAs at critical segments.

Heroin-Induced Transverse Myelitis in a Chronic Heroin User: A Case Report

Transverse myelitis is a rare but documented sequela of heroin use. While the underlying etiology is not clearly elucidated, the prevailing pathophysiologic mechanism amongst existing literature suggests an immune-mediated hypersensitivity reaction due to heroin insufflation following a long period of abstinence. Outcomes vary among the limited reports, but prognosis tends to be poor due to an acute and rapidly progressive disease course. Here, we describe a case of extensive transverse myelitis in a chronic heroin user following heroin insufflation. This report hopes to provide greater insight into the underlying cause of this rare phenomenon due to our patient's discrepancy from the documented norm of heroin abstinence preceding disease onset.

Efficacy of preoperative embolization for metastatic spinal tumor surgery using angiographic vascularity assessment

OBJECTIVES

Preoperative embolization (PE) for metastatic spinal tumors is a method of minimizing intraoperative blood loss during aggressive surgery. This study specified angiographic standards and investigated the influence of these and other factors on blood loss in patients with spinal metastases and various pathologies.

METHODS

The cohort comprised 126 consecutive patients receiving PE from 2015 to 2021. Their clinical, surgical, and angiographic characteristics were reviewed. Standard angiographic grading was used for vascularity assessment. Degree of embolization was divided into complete (≥ 90%), near complete (67 to < 90%), and partial (< 67%). Logistic regression analysis was used to investigate factors predictive of massive blood loss (> 2500 mL). A proportional odds model was used to assess factors predictive of the degree of embolization.

RESULTS

Mean intraoperative blood loss was 1676 mL. Among the patients, 62 had hypervascular tumors and 64 had nonhypervascular tumors, according to the angiographic classification. Intraoperative blood loss differed significantly with embolization degree, both overall (p < 0.001) and in the hypervascular and nonhypervascular groups (p = 0.01 and 0.03). Angiographic hypervascularity, spinal metastasis invasiveness index, and embolization degree were significant predictors of massive blood loss in univariate analysis, but only embolization degree was significant in multivariate analysis. Only the presence of the radiculomedullary artery at the target level was significant in both the univariate and multivariate analyses for embolization degree.

CONCLUSIONS

In addition to pathological classification, angiographic vascularity assessment is valuable. Although complete embolization is a reasonable goal, it is challenging to achieve in cases of visible radiculomedullary artery.

KEY POINTS

• Angiography has a supplementary role in vascularity assessment for spinal metastatic surgery. • Better embolization degree is associated with less intraoperative blood loss in both angiographic hypervascular and nonhypervascular groups. • Presence of radiculomedullary artery in the target level causes worse embolization outcome.

Factors affecting the prognosis of recovery of motor power and ambulatory function after surgery for metastatic epidural spinal cord compression

OBJECTIVE

Metastatic epidural spinal cord compression (MESCC) causes neurological deficits that may hinder ambulation. Understanding the prognostic factors associated with increased neurological recovery and regaining ambulatory functions is important for surgical planning in MESCC patients with neurological deficits. The present study was conducted to elucidate prognostic factors of neurological recovery in MESCC patients.

METHODS

A total of 192 patients who had surgery for MESCC due to preoperative neurological deficits were reviewed. A motor recovery rate ≥ 50% and ambulatory function restoration were defined as the primary favorable endpoints. Factors associated with a motor recovery rate ≥ 50%, regaining ambulatory function, and patient survival were analyzed.

RESULTS

About one-half (48.4%) of the patients had a motor recovery rate ≥ 50%, and 24.4% of patients who were not able to walk due to MESCC before the surgery were able to walk after the operation. The factors "involvement of the thoracic spine" (p = 0.015) and "delayed operation" (p = 0.041) were associated with poor neurological recovery. Low preoperative muscle function grade was associated with a low likelihood of regaining ambulatory functions (p = 0.002). Furthermore, performing the operation ≥ 72 hours after the onset of the neurological deficit significantly decreased the likelihood of regaining ambulatory functions (p = 0.020). Postoperative ambulatory function significantly improved patient survival (p = 0.048).

CONCLUSIONS

Delayed operation and the involvement of the thoracic spine were poor prognostic factors for neurological recovery after MESCC surgery. Furthermore, a more severe preoperative neurological deficit was associated with a lesser likelihood of regaining ambulatory functions postoperatively. Earlier detection of motor weaknesses and expeditious surgical interventions are necessary, not only to improve patient functional status and quality of life but also to enhance survival.

Spinal Tumors: Diagnosis and Treatment

Tumors that present in or around the spine can be challenging to diagnose and treat. A proper workup involves a complete history and physical examination, appropriate staging studies, appropriate imaging of the entire spine, and a tissue biopsy. The biopsy defines the lesion and guides treatment, but in some rare instances, rapid neurological decline may lead to urgent or emergent surgery before it can be analyzed. "Enneking-appropriate" margins should remain the goal for primary tumors while adequate debulking/separation/stabilization are often the goals in metastatic disease. Primary tumors of the spine are rare and often complex tumors to operate on-achieving Enneking-appropriate margins provides the greatest chance of survival while decreasing the chance of local recurrence. Metastatic tumors of the spine are increasingly more common, and timing of surgery must be considered within the greater framework of the patient and the patient's disease, deficits, stability, and other treatments available. The specific tumor type will dictate what other multidisciplinary approaches are available, allowing for chemotherapy and radiation as needed.

Endovascular Repair of Descending Thoracic Aortic Aneurysms

Descending thoracic aortic aneurysms (DTAAs) are an important cause of morbidity and mortality in the elderly. Once diagnosed, they should be surveilled and then repaired at a diameter of 5.5 to 6 cm, depending on the individual patient's physiologic and anatomic risk of repair. Thoracic endovascular aortic repair (TEVAR) is the preferred approach for repair and there are multiple procedural adjuncts that can expand indications for and use of TEVAR. Spinal cord injuries are an important and highly morbid complication after TEVAR and it is imperative to mitigate this risk.

Update on MRI findings of osteomyelitis of long bones in the adult population

OBJECTIVES

To evaluate the usefulness of new and established MRI signs of osteomyelitis in long bones in adults.

METHODS

All patient records over a 9-year period with clinical or MRI suspicion for osteomyelitis were retrospectively reviewed, using strict criteria for proof of infection. Two musculoskeletal radiologists independently reviewed the MRIs of proven osteomyelitis.

RESULTS

Out of 45 MRIs of confirmed osteomyelitis, 2 MRIs (4%) did not show confluent low-signal intensity on T1-weighted images, but all showed confluent high-signal intensity on T2-weighted images. Central hypoenhancing regions of marrow without abscess formation were found in 15-18/35 (43-51%) cases where gadolinium was given. We often found multiple foci of marrow replacement in the same bone. The areas of marrow involvement often had an irregular contour. Penumbra sign, marrow fat globules, and sequestra were uncommon.

CONCLUSION

Multiple foci of bone marrow signal abnormalities, an irregular contour of marrow abnormality, and central marrow hypoenhancement without abscess are common signs of osteomyelitis of long bones in adults. Confluent low T1-signal intensity is not always present.

The unique second wave phenomenon in contrast enhanced ultrasound imaging with nanobubbles

Investigation of nanobubble (NB) pharmacokinetics in contrast-enhanced ultrasound (CEUS) at the pixel level shows a unique phenomenon where the first pass of the contrast agent bolus is accompanied by a second wave. This effect has not been previously observed in CEUS with microbubbles. The objective of this study was to investigate this second-wave phenomenon and its potential clinical applications. Seven mice with a total of fourteen subcutaneously-implanted tumors were included in the experiments. After injecting a bolus of NBs, the NB-CEUS images were acquired to record the time-intensity curves (TICs) at each pixel. These TICs are fitted to a pharmacokinetic model which we designed to describe the observed second-wave phenomenon. The estimated model parameters are presented as parametric maps to visualize the characteristics of tumor lesions. Histological analysis was also conducted in one mouse to compare the molecular features of tumor tissue with the obtained parametric maps. The second-wave phenomenon is evidently shown in a series of pixel-based TICs extracted from either tumor or tissues. The value of two model parameters, the ratio of the peak intensities of the second over the first wave, and the decay rate of the wash-out process present large differences between malignant tumor and normal tissue (0.04 < Jessen-Shannon divergence < 0.08). The occurrence of a second wave is a unique phenomenon that we have observed in NB-CEUS imaging of both mouse tumor and tissue. As the characteristics of the second wave are different between tumor and tissue, this phenomenon has the potential to support the diagnosis of cancerous lesions.

Neurological Impairment Recovery in Surgically Treated Patients With Nontraumatic Spinal Cord Injury

The incidence of nontraumatic spinal cord injury (NTSCI) is reported to be higher than that of traumatic spinal cord injury in many countries, making it an area of growing significance.

Does the anatomical region predict blood loss or neurological deficits in embolized renal cancer spine metastases? A single-center experience with 31 patients

Background

No comparison of a single hypervascular tumor entity in terms of major complications in different spinal regions has been performed. We aimed to evaluate post-embolic and post-operative outcomes in anatomic regions with renal cell carcinoma (RCC) metastases to the spine.

Methods

We retrospectively evaluated data from patients with confirmed, embolized, and surgically treated RCC spine metastases at a single-spine center between 2010 and 2020. Patients were divided into thoracic (TSM) and lumbar (LSM) spine metastasis groups.

Results

Seventeen patients had TSM and 14 had LSM. In all cases, embolization was performed preoperatively. The ΔHb value did not differ between the two groups pre- and postoperatively (p=0.3934). There was no significant difference in intraoperative blood loss between both groups either within 1 day or 2 days after embolization. Neurological deficits occurred in eight patients after embolization or surgery, with no significant difference between TSM (n=5) and LSM (n=3).

Conclusions

Embolization is the standard procedure for the preoperative treatment of hypervascular spinal metastases, possible up to 48 h before surgery, without the risk of higher intraoperative blood loss. Regardless of intraoperative complications, major complications can occur up to several hours after embolization. We recommend surgery the day after embolization to reliably detect neurologic complications from this procedure.

Degeneration of the Sensorimotor Tract in Degenerative Cervical Myelopathy and Compensatory Structural Changes in the Brain

Degenerative cervical myelopathy is a progressive neurodegenerative disease, that has become increasingly prevalent in the aging population worldwide. The current study determined the factors affecting degeneration in the sensorimotor tract with degenerative cervical myelopathy and its relationship with brain structure. We divided patients into hyperintensity (HS) and non-hyperintensity (nHS) groups and measured the fractional anisotropy and apparent diffusion coefficients of the lateral corticospinal tract (CST), fasciculus gracilis and fasciculus cuneatus (FGC). Voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) techniques were used to estimate brain structure changes. Correlation of the modified Japanese Orthopaedic Association (mJOA) score, light touch, pinprick, motor score, and fractional anisotropy (FA) ratios of the CST at different levels were analyzed. Compared to healthy controls, the FA ratios of CST in the HS and nHS groups were decreased at all levels, and the apparent diffusion coefficient (ADC) ratio was increased only at C4/5 levels in the HS group. The FA ratio of FGC was decreased at the C3/4 and C4/5 levels in the HS group and only decreased at the C4/5 level in the nHS group. The ADC ratio was decreased only at the C4/5 level in the HS group. VBM analysis revealed that the volume of the precentral gyrus, postcentral gyrus, and paracentral lobule increased in patients compared to controls. TBSS analysis found no statistical significance between the sensory and motor tracts in white matter. The volume of clusters in HS and nHS groups negatively correlated with the C1/2 FA ratio of the CST. The results showed that the degeneration distance of the CST was longer than the FGC, and the degeneration distance was related to the degree of compression and spinal cord damage. Structural compensation and the neurotrophin family may lead to enlargement of the brain.

Vascular Spinal Cord Disorders

Vascular disorders of the spinal cord are uncommon yet under-recognized causes of myelopathy. Etiologies can be predominantly categorized into clinical and radiographic presentations of arterial ischemia, venous congestion/ischemia, hematomyelia, and extraparenchymal hemorrhage. While vascular myelopathies often produce significant morbidity, recent advances in the understanding and recognition of these disorders should continue to expedite diagnosis and proper management, and ideally improve patient outcomes. This article comprehensively reviews relevant spinal cord vascular anatomy, clinical features, radiographic findings, treatment, and prognosis of vascular disorders of the spinal cord.

Correlations among disability, anti-AQP4 antibody status and prognosis in the spinal cord involved patients with NMOSD

Background

Neuromyelitis optica spectrum disorder (NMOSD) is a rare neuroinflammatory disorder of the central nervous system that typically involves the optic nerve, the spinal cord and other specific brain regions. In relapse of the disease, factors associated with clinical features and lesion severity are important for clinicians to predict disease-related disability.

Methods

We retrospectively analyzed 22 female patients with NMOSD who had spinal cord lesions. Detailed clinical features, onset symptoms, motor disability, relapse episodes, serum aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) autoantibodies and MRI characteristics were documented to correlate their associations with the nadir and three-month Expanded Disability Status Scale (EDSS) scores. Patients with three-month EDSS scores below four (< 4) were categorized as the good outcome group, while those with scores of four or more (> 4) were categorized as the poor outcome group.

Results

In patients with NMOSD, the mean age was 44.5 ± 12.8 years, and the mean three-month EDSS score was 4.3 ± 1.9. A significantly higher all-limb muscle power score was found in the good EDSS group than in the poor EDSS group (p = 0.01). A tendency toward longer follow-up periods and lower anti-AQP4 antibody levels was found in the good outcome group. Serum anti-AQP4 antibodies were present in 86% of patients with NMOSD, and MOG autoantibodies were found in one anti-AQP4 antibody-negative patient (33.3%). In patients with NMOSD, more than 40% of spinal cord lesions were distributed at the middle cervical and upper thoracic levels.

Conclusions

Our findings suggest that EDSS scores and MRC scores at the nadir had significant associations with three-month EDSS scores. The topographic distributions of the spinal cord lesions might relate to different serum anti-AQP4 antibody status. However, further studies will be needed to corroborate this finding.

Risk factors associated with post-operative neurological deterioration in patients with thoracic disc disorders with myelopathy

PURPOSE

Post-operative neurological deterioration (ND) is a severe complication. However, limited literature exists on the ND in thoracic disc disorders with myelopathy (TDM). This study describes the risk factors of neurological deterioration in TDM with instrumentation and fusion.

METHODS

A single-centre review of TDM with instrumentation and fusion during 2006-2019 was performed. Post-operative neurological deterioration was defined as the deterioration of pre-existing neurological function or the appearance of new neurological symptoms. Patients were then grouped into two groups depending on neurological deterioration (ND group) or not (non-ND group). Demographics, radiographic parameters, and surgical characteristics were compared between the two groups.

RESULTS

A total of 257 cases were included, and neurological deterioration occurred in 16 (6.23%) cases. Multivariate analysis revealed spinal canal occupancy ratio > 75%, U-shaped compressed spinal cord in axial MRI, calcified herniated disc, anterior approach, and intra-operative blood loss > 1500 mL were associated with ND. Ten patients (62.5%) had complete neurological recovery within six months, and four patients (25%) had progressive neurological function improvement and equal or better than pre-operation within nine months.

CONCLUSIONS

The rate of neurological deterioration is 6.23%, and a higher spinal canal occupancy ratio, U-shaped compressed spinal cord, calcified herniated disc, anterior approach, and massive intra-operative blood loss were associated with neurological deterioration. Long-term outcomes of neurological deterioration are favourable, and 62.5% of patients experienced complete neurological recovery within six months. Patients with TMD who undergo surgery should be properly informed of the potential risks of neurological deterioration, despite its usually transient nature in most patients.

Vascular Myelopathies

PURPOSE OF REVIEW

Neurologists should be able to identify clinical and neuroimaging features that distinguish vascular disorders from other causes of myelopathy.

RECENT FINDINGS

Although certain clinical features suggest a vascular etiology in acute and chronic myelopathy settings, accurate MRI interpretation within the clinical context is key. Recent studies have shown vascular myelopathies are frequently misdiagnosed as transverse myelitis, and recognition of this diagnostic pitfall is important. Many different vascular mechanisms can cause myelopathy; this article provides a comprehensive review that simplifies disease categories into arterial ischemia, venous congestion/ischemia, hematomyelia, and extraparenchymal hemorrhage.

SUMMARY

It is important to recognize and manage vascular disorders of the spinal cord as significant causes of acute, subacute, and progressive myelopathy.

Neurologic complications of diseases of the aorta

Neurologic complications of diseases of the aorta are common, as the brain and spinal cord function is highly dependent on the aorta and its branches for blood supply. Any disease impacting the aorta may have significant impact on the ability to deliver oxygenated blood to the central nervous system, resulting in ischemia-and if prolonged-cerebral and spinal infarct. The breadth of pathology affecting the aorta is diverse and neurologic complications can vary dramatically based on the location, severity, and underlying etiology. This chapter outlines the major pathology of the aorta while highlighting the associated neurologic complications. This chapter covers the entire spectrum of neurologic complications associated with aortic disease by beginning with a detailed overview of the spinal cord vascular anatomy followed by a discussion of the most common aortic pathologies affecting the nervous system, including aortic aneurysm, aortic dissection, aortic atherosclerosis, inflammatory and infectious aortopathies, congenital abnormalities, and aortic surgery.

Complications and Management of the Thoracic Endovascular Aortic Repair

Endovascular treatment in thoracic aortic diseases has increased in use exponentially since Dake and colleagues first described the use of a home-made transluminal endovascular graft on 13 patients with descending thoracic aortic aneurysm at Stanford University in the early 1990s. Thoracic endovascular aneurysm repair (TEVAR) was initially developed for therapy in patients deemed unfit for open surgery. Innovations in endograft engineering design and popularization of endovascular techniques have transformed TEVAR to the predominant treatment choice in elective thoracic aortic repair. The number of TEVARs performed in the United States increased by 600% from 1998 to 2007, while the total number of thoracic aortic repairs increased by 60%. As larger multicenter trials and meta-analysis studies in the 2000s demonstrate the significant decrease in perioperative morbidity and mortality of TEVAR over open repair, TEVAR became incorporated into standard guidelines. The 2010 American consensus guidelines recommend TEVAR to be “strongly considered” when feasible for patients with degenerative or traumatic aneurysms of the descending thoracic aorta exceeding 5.5 cm, saccular aneurysms, or postoperative pseudoaneurysms. Nowadays, TEVAR is the predominant treatment for degenerative and traumatic descending thoracic aortic aneurysm repair. Although TEVAR has been shown to have decreased early morbidity and mortality compared with open surgical repair, endovascular manipulation of a diseased aorta with endovascular devices continues to have significant risks. Despite continued advancement in endovascular technique and devices since the first prospective trial examined the complications associated with TEVAR, common complications, two decades later, still include stroke, spinal cord ischemia, device failure, unintentional great vessel coverage, access site complications, and renal injury. In this article, we review common TEVAR complications with some corresponding radiographic imaging and their management.

Risk factors for residual neurologic deficits after surgical treatment for epidural abscess in the thoracic or lumbar spine

BACKGROUND CONTEXT

Spinal epidural abscess (SEA) can cause neurologic deficits and needs urgent surgical intervention. Many clinical factors had been proposed to predict surgical outcomes in patients with SEA, but the predictive radiographic risk factors for residual neurologic deficits were not addressed sufficiently.

PURPOSE

To analyze the clinical and radiographic risk factors for residual neurologic deficit in patients with SEA after surgical intervention of the thoracic or lumbar spine.

STUDY DESIGN/SETTING

A retrospective consecutive case series.

PATIENT SAMPLE

From January 2005 through December 2014, 53 patients with primary SEA, confirmed by culture or histopathology, in the thoracic or lumbar spine who underwent posterior-only approach surgery at our hospital.

OUTCOME MEASURES

Neurologic status was assessed using the Frankel grading system preoperatively, postoperatively, and at final follow-up.

METHODS

The patients were allocated into two groups based on the presence of postoperative residual neurologic deficits. Patients' demographic, clinical, and factors based on magnetic resonance imaging (MRI) were analyzed for their influence on residual neurologic deficits. Clinical factors included age, sex, diabetes, comorbidities, pathogens, affected spinal levels, the interval between onset of symptoms to surgery, preoperative neurologic status, presence of cauda equina syndrome, and surgical procedures. MRI factors included the distribution of abscesses within the spinal canal, presence of ring enhancement, presence of paravertebral abscess or psoas abscess, canal compromise anteroposterior (AP) ratio and cross-sectional area ratio, abscess length, and abscess thickness.

RESULTS

Thirty-five of the 53 patients (66%) had preoperative neurologic deficits, and 21 of 53 patients (40%) had postoperative residual neurologic deficits. Patients' neurologic status improved significantly after the surgery (p<.001). Risk factors including age, diabetes, cauda equina syndrome, presence of anterior with posterior (A+P) dural abscess, canal compromise AP ratio, cross-sectional area ratio, abscess length, and abscess thickness were significantly correlated with postoperative residual neurologic deficits. In multivariate logistic regression analysis, age ≥70 years, preoperative cauda equina syndrome, abscess length ≥5.5 cm and abscess thickness ≥0.8 cm were the four most significant factors related to residual neurologic deficits.

CONCLUSIONS

In patients with SEA of the thoracic and lumbar spine, age ≥70 years, preoperative cauda equina syndrome, abscess length ≥5.5 cm and abscess thickness ≥0.8 cm were the most significant preoperative risk factors for residual neurologic deficits after surgery.

Collateral Circulation in Spinal Cord Injury: A Comprehensive Review

Surgery is the most common cause of spinal cord ischemia; it is also caused by hemodynamic changes, which disrupt the blood flow. Direct ligation of the spinal arteries, especially the Adamkiewicz artery is involved as well. Other causes of spinal cord ischemia include arteriography procedures, thoracic surgery, epidural and rachianesthesia, foraminal infiltration, arterial dissection, systemic hypotension, emboligenic heart disease, thoracic disc herniation, and compression. Understanding the vascular anatomy of the spinal cord is essential to develop optimal strategies for preventing ischemic injuries to the spinal cord. During ischemia, a rich network of intra and paraspinal collaterals allow enough blood flow to compensate the intensity of spinal cord ischemia. In case of interruption of flow of a main artery, the collateral artery increases its flow to maintain perfusion to the tissues. Avoiding spinal cord ischemia by using collateral circulation is necessary to prevent the establishment of hypovolemia, hyperthermia and elevations in venous pressures. The objective of this narrative review is to present the current concepts of spinal collateral circulation and its role in the setting of ischemic events, affecting the vascular supply of the spinal cord.

Anterior Spinal Artery Syndrome: Rare Precedented Reason of Postoperative Plegia After Spinal Deformity Surgery: Report of 2 Cases

BACKGROUND

Complications in spinal deformity surgery vary from insignificant to severe. Apart from direct mechanical insult, ischemia can also cause spinal cord injury. Ischemic injury may be detected during surgery or may manifest itself postoperatively. We present 2 cases of anterior spinal artery syndrome.

CASE DESCRIPTION

In the first case, a 12-year-old girl developed anterior spinal artery syndrome resulting in total quadriplegia 8 hours after spinal deformity surgery. She was treated with a steroid, immunoglobulin, and low-molecular-weight heparin. She showed complete recovery at 1 year postoperatively both clinically and radiographically. In the second case, a 62-year-old woman experienced sudden loss of motor evoked potentials intraoperatively during dural tear repair after sagittal and coronal alignment was established. The paraplegic patient was diagnosed with anterior spinal artery syndrome at the thoracic level postoperatively. She was treated with a steroid and heparin. At 1 year postoperatively, she has gained much of her strength and has myelomalacia in her spinal cord.

CONCLUSIONS

Anterior spinal artery syndrome is a serious condition with a generally poor prognosis. Though treatment should be directed at the underlying cause, the best strategy is to prevent it from occurring. Peroperative blood pressure control, intraoperative neuromonitoring, avoidance from mechanical stress during surgery, and close neurologic and hemodynamic monitorization postoperatively should be performed.

The Safety Profile of Intentional or Iatrogenic Sacrifice of the Artery of Adamkiewciz and Its Vicinity's Spinal Segmental Arteries: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

There is paucity of consensus on whether (1) the artery of Adamkiewicz (AoA) and (2) the number of contiguous segmental spinal arteries (SSAs) that can be safely ligated without causing spinal cord ischemia. The objective of this review is to determine the risk of motor neurological deficits from iatrogenic sacrifice of the (1) AoA and (2) its vicinity's SSAs.

METHODS

Systematic review of the spine and vascular surgery was carried out in accordance to PRISMA guidelines. Outcomes in terms of risk of postoperative motor neurological deficit with occlusion of the AoA, bilateral contiguous SSAs, or unilateral contiguous SSAs were analyzed.

RESULTS

Ten articles, all retrospective case series, were included. Three studies (total N = 50) demonstrated a postoperative neurological deficit risk of 4.0% when the AoA is occluded. When 1 to 6 pairs of SSAs (without knowledge of AoA location) were ligated, the postoperative neurological deficit risk was 0.6%, as compared with 5.4% when more than 6 bilateral pairs of SSAs were ligated (relative risk [RR] = 0.105, 95% CI 0.013-0.841, P = .0337). For unilateral ligation of SSAs of two to nine levels, the risk of postoperative neurological deficit does not exceed 1.3%.

CONCLUSION

The current best evidence indicates that (1) occlusion of the AoA and (2) occlusion of up to 6 pairs of SSAs is associated with a low risk of postoperative neurological deficit. This limited number of low quality studies restrict the ability to draw definitive conclusions. Ligation of AoA and SSAs should only be undertaken when absolutely required to mitigate the small but devastating risk of paralysis.

Complications of Thoracolumbar Adult Spinal Deformity Surgery

Adult spinal deformity (ASD) is a challenging problem for spine surgeons given the high risk of complications, both medical and surgical. Surgeons should have a high index of suspicion for medical complications, including cardiac, pulmonary, thromboembolic, genitourinary and gastrointestinal, renal, cognitive and psychiatric, and skin conditions, in the perioperative period and have a low threshold for involving specialists. Surgical complications, including neurologic injuries, vascular injuries, proximal junctional kyphosis, durotomy, and pseudarthrosis and rod fracture, can be devastating for the patient and costly to the health-care system. Mortality rates have been reported to be between 1.0% and 3.5% following ASD surgery. With the increasing rate of ASD surgery, surgeons should properly counsel patients about these risks and have a high index of suspicion for complications in the perioperative period.

Man With Sudden Paralysis: Insidious Spinal Cord Infarction due to a Non-Ruptured Abdominal Aortic Aneurysm

BACKGROUND

Acute infarctions of the spinal cord are rare events characterized by sudden paralysis or sensory deficits below the level of injury. Etiologies include spinal cord trauma, vascular injury, arterial dissection, thromboembolic disease, chronic inflammatory conditions, or mass effect on the spinal cord.

CASE REPORT

A 63-year-old male presented to the emergency department with sudden-onset bilateral leg numbness and weakness. His physical examination was notable for decreased light touch and temperature sensation and bilateral lower-extremity paresis. Initial magnetic resonance imaging (MRI) of his spine did not show cord injuries. Computed tomography angiography of his chest, abdomen, and pelvis demonstrated a 7.5-cm non-ruptured infrarenal abdominal aortic aneurysm (AAA) extending into bilateral iliac arteries. The patient was diagnosed with clinical spinal cord infarction secondary to a thromboembolic event from his AAA. A repeat MRI 15 h later showed spinal cord infarction from T8 down to the conus. He received an endovascular aortic repair and was ultimately discharged to rehabilitation with slightly improved lower-extremity strength. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Atraumatic cord syndrome is exceedingly rare and is associated with dissection or complication of aortic aneurysm repair. There are very few reported cases of thrombotic events leading to ischemic cord syndrome. When presented with a patient with symptoms consistent with cord syndrome in the absence of trauma or mass effect on the spinal cord, providers should work up for vascular etiology.

Delayed-Onset Paraplegia Due to Spinal Cord Infarction After Repeated Tumor Excision Surgeries of the Thoracic Spine

Tumor excision surgeries of the spine present a distinct challenge regarding the maintenance of spinal cord blood supply because they often require preoperative embolization of segmental arteries, ligation of the corresponding nerve roots, and circumferential exposure of the dural sac. The authors present a case of delayed-onset spinal cord infarction after repeated tumor excision surgeries of the thoracic spine. A 49-year-old man had undergone a left nephrectomy for renal cell carcinoma, 2 pulmonary metastasectomies, and excision of a left sixth rib metastasis before referral to the authors' institution. He had a recurrence of the bone metastasis involving the left fourth and fifth ribs and T5 vertebra. He underwent 3 tumor excision surgeries, including spondylectomy of T5 and T7, for the repeated tumor recurrences involving the thoracic spine. These surgeries required preoperative embolization of 9 segmental arteries at 6 consecutive levels and ligation of 6 nerve roots at 3 consecutive levels. Thirty hours after the third surgery, the neurologic deficit worsened. The postoperative paraplegia was diagnosed as delayed-onset spinal cord infarction via magnetic resonance imaging. This is the first case report describing delayed-onset paraplegia due to spinal cord ischemia caused by embolization of segmental arteries and ligation of nerve roots in multi-spinal levels for spine tumor surgeries. In spine tumor surgery, embolization of bilateral segmental arteries at 4 or more consecutive levels and/or ligation of bilateral nerve roots pose a risk for ischemic spinal cord disease. [Orthopedics. 2019; 42(1):e131-e134.].

Development of Predictive Algorithms for Pre-Treatment Motor Deficit and 90-Day Mortality in Spinal Epidural Abscess

BACKGROUND

Spinal epidural abscess is a high-risk condition that can lead to paralysis or death. It would be of clinical and prognostic utility to identify which subset of patients with spinal epidural abscess is likely to develop a motor deficit or die within 90 days of discharge.

METHODS

We identified all patients ≥18 years of age who were admitted to our hospital system with a diagnosis of spinal epidural abscess during the period of 1993 to 2016. Explanatory variables were collected retrospectively. Bivariate and multivariable logistic regression was performed using these variables to identify independent predictors of motor deficit and 90-day mortality. Nomograms were then constructed to quantify the risk of these outcomes.

RESULTS

Of the 1,053 patients we identified with spinal epidural abscess, 362 presented with motor weakness. One hundred and thirty-four patients died within 90 days of discharge, inclusive of those who died during hospitalization. Multivariable logistic regression yielded 8 independent predictors of pre-treatment motor deficit and 8 independent predictors of 90-day mortality. We constructed nomograms that generated a probability of pre-treatment motor deficit or 90-day mortality on the basis of the presence of these factors.

CONCLUSIONS

By quantifying the risk of pre-treatment motor deficit and 90-day mortality, our nomograms may provide useful prognostic information for the treatment team. Timely treatment of neurologically intact patients with a high risk of developing a motor deficit is necessary to avoid residual motor weakness and improve survival.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of Levels of Evidence.

Morphometric Analysis of Rat Spinal Cord Angioarchitecture by Phase Contrast Radiography: From 2D to 3D Visualization

STUDY DESIGN

An advanced imaging of vasculature with synchrotron radiation X-ray in a rat model.

OBJECTIVE

To develop the potential for quantitative assessment of vessel network from two-dimensional (2D) to 3D visualization by synchrotron radiation X-ray phase contrast tomography (XPCT) in rat spinal cord model.

SUMMARY OF BACKGROUND DATA

Investigation of microvasculature contributes to the understanding of pathological development of spinal cord injury. A few of X-ray imaging is available to visualize vascular architecture without usage of angiography or invasive casting preparation.

METHODS

A rat spinal cord injury model was produced by modified Allen method. Histomorphometric detection was simultaneously analyzed by both histology and XPCT from 2D to 3D visualization. The parameters including tissue lesion area, microvessel density, vessel diameter, and frequency distribution of vessel diameter were evaluated.

RESULTS

XPCT rendered the microvessels as small as capillary scale with a pixel size of 3.7 μm. It presented a high linear concordance for characterizing the 2D vascular morphometry compared with the histological staining (r = 0.8438). In the presence of spinal cord injury model, 3D construction quantified the significant angioarchitectural deficiency in the injury epicenter of cord lesion (P<0.01).

CONCLUSION

XPCT has a great potential to detect the smallest vascular network with pixel size up to micron dimension. It is inferred that the loss of abundant microvessels (≤40 μm) is responsible for local ischemia and neural dysfunction. XPCT holds a promise for morphometric analysis from 2D to 3D imaging in experimental model of neurovascular disorders.

LEVEL OF EVIDENCE

N/A.

Nonoperative Management of Spinal Epidural Abscess: Development of a Predictive Algorithm for Failure

BACKGROUND

Prompt diagnosis and treatment are critical in spinal epidural abscess, as delay can lead to paralysis or death. The initial management decision for spinal epidural abscess is not always clear, with the literature showing conflicting results. When considering nonoperative management, it is crucial to avoid failure of treatment, given the neurologic compromise incurred through failure. Unfortunately, data regarding risk factors associated with failure are scarce.

METHODS

All patients admitted to our hospital system with a diagnosis of spinal epidural abscess from 1993 to 2016 were identified. Patients who were ≥18 years of age and were initially managed nonoperatively were included. Explanatory variables and outcomes were collected retrospectively. Bivariate and multivariable analyses were performed on these variables to identify independent predictors of failure of nonoperative treatment. A nomogram was constructed to generate a risk of failure based on these predictors.

RESULTS

We identified 367 patients who initially underwent nonoperative management. Of these, 99 patients underwent medical management that failed. Multivariable logistic regression yielded 6 independent predictors of failure: a presenting motor deficit, pathologic or compression fracture in affected levels, active malignancy, diabetes mellitus, sensory changes, and dorsal location of abscess. We constructed a nomogram that generates a probability of failure based on the presence of these factors.

CONCLUSIONS

By quantifying the risk of failure on the basis of the presence of 6 independent predictors of treatment failure, our nomogram may provide a useful tool for the treatment team when weighing the risks and benefits of initial nonoperative treatment compared with operative management.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Progress in Intraoperative Neurophysiological Monitoring for the Surgical Treatment of Thoracic Spinal Stenosis

Thoracic spinal stenosis (TSS) is a group of clinical syndromes caused by thoracic spinal cord compression, which always results in severe clinical complications. The incidence of TSS is relatively low compared with lumbar spinal stenosis, while the incidence of spinal cord injury during thoracic decompression is relatively high. The reported incidence of neurological deficits after thoracic decompression reached 13.9%. Intraoperative neurophysiological monitoring (IONM) can timely provide information regarding the function status of the spinal cord, and help surgeons with appropriate performance during operation. This article illustrates the theoretical basis of applying IONM in thoracic decompression surgery, and elaborates on the relationship between signal changes in IONM and postoperative neurological function recovery of the spinal cord. It also introduces updated information in multimodality IONM, the factors influencing evoked potentials, and remedial measures to improve the prognosis.

Spinal cord injury after thoracic endovascular aortic aneurysm repair

PURPOSE

Thoracic endovascular aortic aneurysm repair (TEVAR) has become a mainstay of therapy for aneurysms and other disorders of the thoracic aorta. The purpose of this narrative review article is to summarize the current literature on the risk factors for and pathophysiology of spinal cord injury (SCI) following TEVAR, and to discuss various intraoperative monitoring and treatment strategies.

SOURCE

The articles considered in this review were identified through PubMed using the following search terms: thoracic aortic aneurysm, TEVAR, paralysis+TEVAR, risk factors+TEVAR, spinal cord ischemia+TEVAR, neuromonitoring+thoracic aortic aneurysm, spinal drain, cerebrospinal fluid drainage, treatment of spinal cord ischemia.

PRINCIPAL FINDINGS

Spinal cord injury continues to be a challenging complication after TEVAR. Its incidence after TEVAR is not significantly reduced when compared with open thoracoabdominal aortic aneurysm repair. Nevertheless, compared with open procedures, delayed paralysis/paresis is the predominant presentation of SCI after TEVAR. The pathophysiology of SCI is complex and not fully understood, though the evolving concept of the importance of the spinal cord's collateral blood supply network and its imbalance after TEVAR is emerging as a leading factor in the development of SCI. Cerebrospinal fluid drainage, optimal blood pressure management, and newer surgical techniques are important components of the most up-to-date strategies for spinal cord protection.

CONCLUSION

Further experimental and clinical research is needed to aid in the discovery of novel neuroprotective strategies for the protection and treatment of SCI following TEVAR.

Modified En Bloc Spondylectomy for Tumors of the Thoracic and Lumbar Spine: Surgical Technique and Outcomes

BACKGROUND

Total en bloc spondylectomy (TES) for the treatment of spinal tumors decreases local recurrence and improves survival compared with intralesional resection. TES approaches vary in both the number of stages to complete the procedure and instruments with which osteotomies are performed.

METHODS

We describe a 2-stage technique that employs the use of threadwire saws. We performed a retrospective review of cases of primary tumors and solitary metastases involving the thoracic or lumbar spine treated with use of our modified technique at our institution between 2010 and 2016, identifying eligible patients by searching for specific phrases in operative reports found in our oncologic database. Clinical notes, operative notes, imaging reports, and pathology reports were reviewed for all patients.

RESULTS

Thirty-three patients underwent our modified technique, in which we pass a threadwire saw between the vertebral body and the thecal sac. The most common tumor type was chordoma (64%), and tumors were most commonly located in the lumbar spine (61%). There were no intraoperative injuries to the spinal cord or great vessels. One patient experienced a dural tear secondary to the passage of a saw. Seventeen (52%) of the patients had perioperative complications, with 1 death. Seven (22%) of the patients had complications occurring within 90 days after discharge, and 8 (25%) had complications occurring >90 days after discharge. Instrumentation failure was observed in 8 cases (25%). Negative margins were obtained in 94% of the cases. Local recurrence was observed in 2 cases (6%). The majority of patients had normal motor function at the time of the most recent follow-up.

CONCLUSIONS

Our modified en bloc spondylectomy represents an effective technique for the resection of spinal tumors in selected patients, allowing for visualization of vessels anterior to the spine and the avoidance of spinal cord injury.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Rates of Spinal Cord Infarction After Repair of Aortic Aneurysm or Dissection

BACKGROUND AND PURPOSE

The rate of spinal cord infarction (SCI) after surgical or endovascular repair of an aortic aneurysm or dissection is unclear.

METHODS

Using administrative claims data, we identified adult patients discharged from nonfederal acute care hospitals in California, New York, and Florida who underwent surgical or endovascular repair of an aortic aneurysm or dissection between 2005 and 2013. Patients with SCI diagnosed before the aortic repair were excluded. Our primary outcome was an SCI during the index hospitalization for aortic repair. Descriptive statistics were used to estimate crude rates of SCI. Analyses were stratified by whether the aneurysm or dissection had ruptured and by type of repair (surgical versus endovascular).

RESULTS

We identified 91 212 patients who had repair of an aortic aneurysm or dissection. SCI occurred in 235 cases (0.26%; 95% confidence interval [CI], 0.22%-0.29%). In patients with ruptured aneurysm or dissection, the rate of SCI was 0.74% (95% CI, 0.60%-0.88%) compared with 0.16% (95% CI, 0.13%-0.19%) with unruptured aneurysm. In secondary analyses, rates of SCI were similar after endovascular repair (0.91%; 95% CI, 0.62%-1.19%) compared with surgical repair (0.68%; 95% CI, 0.53%-0.83%; P=0.147) of ruptured aortic aneurysm or dissection; however, rates of SCI were higher after surgical repair (0.20%; 95% CI, 0.15%-0.25%) versus endovascular repair (0.11%; 95% CI, 0.08%-0.14%; P<0.001) of unruptured aneurysm.

CONCLUSIONS

SCI occurs in ≈1 in 130 patients undergoing aortic dissection or ruptured aortic aneurysm repair and in 1 in 600 patients undergoing unruptured aortic aneurysm repair.

Development of a modified model of spinal cord ischemia injury by selective ligation of lumbar arteries in rabbits

STUDY DESIGN

Experimental study.

OBJECTIVE

The aim of this study is to develop a modified model of spinal cord ischemia in rabbits.

SETTINGS

Shenzhen Key Laboratory of Spine Surgery, Shenzhen, China.

METHODS

In total, 20 New Zealand rabbits were divided into the following four groups according to the level of ligation of bilateral lumbar arteries: (1) group A, sham group, no ligation, n=5; (2) group B, ligation of bilateral lumbar arteries at three levels (L2-L4, n=5); (3) group C, ligation of bilateral lumbar arteries at four levels (L2-L5, n=5); and (4) group D, ligation of bilateral lumbar arteries at five levels (L1-L5, n=5). The latency of motor-evoked potentials was measured intraoperatively and the modified Tarlov grades were scored, followed by a histological observation of spinal cord, on the seventh day after surgery.

RESULTS

All 10 rabbits in Group A and Group B were electrophysiologically, neurologically and histologically normal. In Group C, moderate spinal cord ischemia injury was found in three of five rabbits: they had prolonged latency of motor-evoked potentials and neuronal karyopyknosis in the anterior horn of spinal cord, and the average Tarlov score was 4.2±0.8. In Group D, severe spinal cord ischemia injury was recorded in all the five rabbits: the latency of motor-evoked potential prolonged in one rabbit, whereas the waveform disappeared in four rabbits; loss of neurons and vacuolation of gray matter were seen in spinal cord sections, and the average Tarlov score was 0.6±0.9.

CONCLUSION

Selective ligation of lumbar arteries was a modified method to induce feasible and reproducible model of spinal cord ischemia in rabbits.

The incidence and risk factors of postoperative neurological deterioration after posterior decompression with or without instrumented fusion for thoracic myelopathy

The aim of this study was to explore the incidence and risk factors of postoperative neurological deterioration after posterior decompression with or without instrumented fusion for thoracic myelopathy, and hope to provide references in decision-making and surgical planning for both spinal surgeon and thoracic stenosis patients.By retrieving the medical records from January 2001 to November 2015, 168 patients were retrospectively reviewed. According to the occurrence of postoperative neurological deterioration, patients were divided into 2 groups: neurological deterioration (ND) group and non-ND group. To investigate risk values for the occurrence of ND, 3 categorized factors were analyzed statistically: patient characteristics-preoperative data of age, sex, body mass index, bone mineral density, the duration of disease (from first symptoms to operation), the preoperative neurological function (Frankel grade), and diagnosis; surgical variables-surgery time, the amount of bleeding, mean arterial pressure, intervertebral fusion or not, and instrumentation or not; radiographic parameters-the spinal canal occupancy ratio, location of the lesion, thoracic kyphosis, and kyphosis correction.Postoperative neurological deterioration was developed in 23 of 168 patients (13.7%), and were enrolled as ND group. There was no statistically significant difference between the 2 groups in age at operation, sex composition, body mass index, and bone mineral density. The preoperative diagnosis presented significant difference between the 2 groups, because ossification of posterior longitudinal ligament combined with ossification of the ligamentum flavum was more common in ND group, whereas ossification of the ligamentum flavum alone was more common in non-ND group. There was no difference between the 2 groups in mean surgery time, the incidence of intraoperative direct trauma, and the number of patients that received instrumentation. The mean bleeding was much more in ND group than that in non-ND group, and the mean arterial pressure was lower in ND group than that in non-ND group. Also, the mean spinal canal occupancy ratio was more severe in ND group than that in non-ND group. There were no statistically significant difference between the 2 groups in stenosis location and preoperative thoracic kyphosis. The mean kyphosis correction was more significant in ND group. When included in a multivariate logistic regression model, thoracic disc herniation + ossification of posterior longitudinal ligament, spinal canal occupancy ratio more than 70%, bleeding more than 800 mL, and mean arterial pressure less than 81 mm Hg were independently associated with the postoperative neurological deterioration.In conclusion, ossification of posterior longitudinal ligament combined with ossification of the ligamentum flavum, spinal canal occupancy ratio more than 70%, intraoperative bleeding more than 800 mL, and mean arterial pressure less than 81 mm Hg are risk factors for the occurrence of postoperative neurologic deterioration. Improving surgical technique, shortening operation time, and paying more attention to hemostasis could provide opportunities to reduce the incidence of neurologic deterioration and to improve therapeutic outcomes.