Journal Scan – This Month in Other Journals, August 2017

Charidimou A, Boulouis G, Xiong L, et al. Cortical superficial siderosis and first-ever cerebral hemorrhage in cerebral amyloid angiopathy. Neurology. 2017;88(17):1607-1614. doi:10.1212/WNL.0000000000003866.

Cortical superficial siderosis (cSS) on T2*-GRE or SWI is a strong hemorrhagic signature of cerebral amyloid angiopathy (CAA)—a common small vessel disease characterized by cerebrovascular amyloid deposition affecting superficial cortical microvascular networks, leading to spontaneous lobar intracerebral hemorrhage (ICH). Cortical superficial siderosis results from bleeding episodes within or adjacent to cortical sulci, presumably from amyloid-laden superficial cortical and leptomeningeal arterioles. Cortical superficial siderosis is a common manifestation of cerebral amyloid angiopathy, being found in 40%–60% of patients.

In this study, consecutive patients meeting modified Boston criteria for probable CAA in the absence of ICH from a single-center cohort were analyzed. Cortical superficial siderosis and other small vessel disease MRI markers were assessed according to recent consensus recommendations. Patients were followed prospectively for future incident symptomatic lobar ICH.

The cohort included 236 patients with probable CAA without lobar ICH at baseline. Cortical superficial siderosis prevalence was 34%. During a median follow-up of 3.26 years, 27 of 236 patients (11.4%) experienced a first-ever symptomatic lobar ICH. Cortical superficial siderosis was a predictor of time until first ICH. The risk of symptomatic ICH at 5 years of follow-up was 19% for patients with cortical superficial siderosis at baseline vs 6% for patients without cortical superficial siderosis. In multivariable Cox regression models, cortical superficial siderosis presence was the only independent predictor of increased symptomatic ICH risk during follow-up.

The authors found that cortical superficial siderosis on T2*-GRE/SWI MRI is associated with an increased risk of future first-ever symptomatic lobar ICH. The prognostic value of cSS in this setting was strong and independent of age and other neuroimaging markers of CAA severity, including lobar cerebral microbleed burden and WMH. Hence, cortical superficial siderosis may help stratify future bleeding risk even in symptomatic patients with CAA coming to medical attention without ICH, with implications for prognosis and treatment decisions.

3 Figures, 2 Tables

Backes D, Rinkel GJE, Greving JP, et al. ELAPSS score for prediction of risk of growth of unruptured intracranial aneurysms. Neurology. 2017;88(17):1600-1606. doi:10.1212/WNL.0000000000003865.

Approximately 3% of the adult population has an unruptured intracranial aneurysm. With increasing availability and improved quality of noninvasive imaging, an increasing number of unruptured aneurysms are being detected. Small aneurysms are often left untreated because the risk of aneurysm rupture does not outweigh the risk of morbidity and mortality from treatment complications. Follow-up imaging of untreated intracranial aneurysms is recommended because a proportion of these aneurysms grow over time and may hemorrhage. Guidelines from the American Heart Association and European Stroke Organization lack recommendations for which patients and at what time interval follow-up imaging should be considered. In this international multicenter cohort study, the authors pooled data from patients with unruptured intracranial aneurysms and follow-up imaging from 10 centers in 5 countries.

From 10 cohorts of patients with unruptured intracranial aneurysms and follow-up imaging, they pooled individual data on sex, population, age, hypertension, history of subarachnoid hemorrhage, and aneurysm location, size, aspect ratio, and shape (but not on smoking) during follow-up and family history of intracranial aneurysms in 1,507 patients with 1,909 unruptured intracranial aneurysms and used aneurysm growth as outcome.

Aneurysm growth occurred in 257 patients (17%) and 267 aneurysms (14%) during 5,782 patient-years of follow-up. Predictors for aneurysm growth were earlier subarachnoid hemorrhage, location of the aneurysm (less risk for ACOM), age >60 years, population (Finnish and Japanese higher risk), size of the aneurysm (larger is higher risk), and shape of the aneurysm (irregular is bad). These 6 factors make the mnemonic of ELAPSS. Sex, hypertension, and aspect ratio were excluded from the model because of their limited predictive value. This score gives insight into which patients with unruptured intracranial aneurysms have a high risk of aneurysm growth, which can help patients and their physicians decide on the need for and timing of follow-up imaging.

3 Tables, 2 Figures

Platz J, Wagner M, Güresir E, et al. Early diffusion-weighted MRI lesions after treatment of unruptured intracranial aneurysms: a prospective study. J Neurosurg. 2017;126(4):1070-1078. doi:10.3171/2016.2.JNS152456.

Patients (n=99) with unruptured intracranial aneurysms were assigned to undergo clipping (n=62) or coiling (n=37) according to interdisciplinary consensus and subsequently underwent DWI 1 day before and 1 day after aneurysm treatment. Newly detected lesions by DWI after treatment were the primary end point of this prospective study. Lesions detected by DWI were categorized as follows: A) 1–3 DWI spots < 10 mm, B) > 3 DWI spots < 10 mm, C) single DWI lesion > 10 mm, or D) DWI lesion related to surgical access.

Diffusion-weighted MRI detected new lesions in 27 (43.5%) after clipping and 20 (54.1%) patients after coiling, which was not significantly different. The pattern of lesions detected by DWI varied significantly between groups. Microembolic lesions (A and B) found on DWI were detected more frequently after coiling (A, 14 cases; B, 5 cases) than after clipping (A, 5 cases), whereas C and D were rare after coiling (C, 1 case) and occurred more often after clipping (C, 12 cases and D, 10 cases).

For coiling, this phenomenon is well known from previous studies, which show incidences of new lesions on DWI of between 10% and 77%. Several explanations have been postulated as to etiology of the diffusion hits, such as thrombus formation at the catheter or guidewire, microemboli created by packing the aneurysmal sac densely with coils, thrombosis within the aneurysmal sac, or dislocation of coils protruding into the parent vessel. Friable arteriosclerotic plaques and iatrogenic dissection of the parent vessel are possible mechanisms, as is the formation of air bubbles during contrast injection or during the introduction and placement of coils and other materials. Manipulations during the arterial access and in the parent vessel might explain the occurrence of DWI-detected lesions proximal to the treated aneurysm. Even after diagnostic angiography alone, new silent lesions have been detected by DWI in 26% of patients. This study confirmed that even subtle and subclinical lesions can be detected, which may correlate with the risk of embolism or branch occlusion. For coiling, the avoidance of thromboembolism by antithrombotic medication and testing for aspirin or clopidogrel resistance may lower the rate of microemboli. Of course, efforts should be made to avoid injection or infusion of micro–air bubbles during catheterization or introduction of implants. For surgical cases, the authors suggest avoiding clipping of aneurysms with heavily calcified necks.

3 Figures, 5 Tables

de Havenon A, Haynor DR, Tirschwell DL, et al. Association of Collateral Blood Vessels Detected by Arterial Spin Labeling Magnetic Resonance Imaging With Neurological Outcome After Ischemic Stroke. JAMA Neurol. 2017;74(4):453. doi:10.1001/jamaneurol.2016.4491.

This retrospective cohort study examined 38 patients after AIS admitted to a tertiary academic medical center between 2012 and 2014 who underwent MRI with ASL. ASL images were graded for the presence of collaterals by 2 neuroradiologists. Modified Rankin Scale (mRS) scores at discharge and other composite data were abstracted from the medical record by a neurologist blinded to radiologic data. In 25 of 38 patients (65.8%), collaterals were detected using ASL, which were significantly associated with both a good outcome and a 1-point decrease in mRS score at discharge. In a multivariable ordinal logistic regression model, controlling for admission NIH Stroke Scale score, history of atrial fibrillation, premorbid mRS score, and stroke parent artery status, there was a strong association between the presence of ASL collaterals and a 1-point decrease in the mRS score at discharge. Following AIS, the presence of ASL collaterals is strongly associated with better neurological outcome at hospital discharge. This novel association between ASL collaterals and improved neurologic outcome may help guide prognosis and management.

ASL images were obtained on a 3T MAGNETOM Tim Trio System(Siemens Healthcare), using a single subtraction, second version (QUIPSS II) with thin-slice TI, periodic saturation (Q2TIPS) and proximal inversion with control for off-resonance effects with the following parameters: 52 label and control image pairs with slice thickness = 5mm for 21 slices or 7.5mm for 17 slices (dependent on protocol); TE=12 milliseconds; time to inversion 1 (bolus duration) = 800 milliseconds; time to inversion (time from application of labeling pulse to image acquisition) = 1800 milliseconds; TR= 3400 milliseconds; BW= 2367 Hz/pixel; flip angle 90; and FOV = 192; 64 × 64 matrix. Arterial spin labeling images underwent inline motion correction and were acquired without vascular crusher gradients.

Schusse CM, Smith K, Drees C. Outcomes after hemispherectomy in adult patients with intractable epilepsy: institutional experience and systematic review of the literature. J Neurosurg. 2017;16(3):1-9. doi:10.3171/2016.9.JNS151778.

The term “hemispherotomy” refers to several more recently developed approaches that similarly aim to transect all crucial interhemispheric connections while minimizing brain removal. Functional hemispherectomy or hemispherotomy has remained an invaluable tool in treating focal or hemispheric epilepsy due to various etiologies (vascular insults, hemimegalencephaly, Rasmussen encephalitis). Although the procedure has been used for pediatric patients with epilepsy for > 80 years, its use in the adult population has been comparatively scarce. To date, there have been only 84 cases of adult hemispherectomy in the literature. Many reasons have been cited, but concerns about lack of neuroplasticity in adults and the suspected potential for significant functional decline are generally the most common.

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. 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. They conclude that 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.

Yagi K, Nakagawa H, Okazaki T, et al. Noninfectious prevertebral soft-tissue inflammation and hematoma eliciting swelling after anterior cervical discectomy and fusion. J Neurosurg Spine. 2017;26(4):459-465. doi:10.3171/2016.9.SPINE16520.

The authors investigated factors eliciting severe dysphagia and its relationship with prevertebral inflammation in patients who had undergone ACDF. The clinical data of 299 patients who underwent 307 ACDF procedures for cervical radiculopathy or myelopathy between December 2007 and August 2014 were reviewed. 7 patients suffered severe prolonged and/or delayed dysphagia and odynophagia that prevented ingestion. In all 7 patients, the prevertebral space was enlarged. In 5 (1.6%) the symptom was thought to be associated with prevertebral soft-tissue edema; in all 5 an inflammatory response, hyperthermia, and an increase in the white blood cell count and in C-reactive protein level was observed. After 2 procedures (0.7%), they noted prevertebral hematoma without an inflammatory response.

Of the 307 ACDF procedures performed in 299 patients, 7 (2.3%) elicited severe postoperative swallowing disturbance that resolved within a few weeks. They attributed swallowing disturbance in 5 patients to noninfectious prevertebral inflammation and in the other 2 to PVH. None manifested infection and/or pharyngoesophageal perforation. This is the first report to document that prevertebral soft-tissue edema can be accompanied by a noninfectious inflammatory response manifesting as hyperthermia and an increase in the WBC count and CRP level. Although post-ACDF dysphagia and odynophagia in the presence of prevertebral soft-tissue swelling and a general inflammatory response should suggest the possibility of pharyngoesophageal perforation and/or surgical site infection, these are rare complications, and noninfectious inflammation in prevertebral tissue can mimic surgical site infection.

3 Figures, 2 Tables

Assinck P, Duncan GJ, Hilton BJ, Plemel JR, Tetzlaff W. Cell transplantation therapy for spinal cord injury. Nat Neurosci. 2017;20(5):637-647. doi:10.1038/nn.4541.

In this review, the authors discuss the five most commonly proposed mechanisms through which cell transplantation is thought to promote functional benefits following SCI: neuroprotection, immunomodulation, axon sprouting and/or regeneration, neuronal relay formation and myelin regeneration. They address their definitions, discuss how researchers might provide more definitive evidence that they mediate functional improvements and highlight the obstacles to making cell transplantation a viable treatment option.

Numerous cell types have been assessed for their capacity to treat SCI with transplantation. The most widely studied are Schwann cells, neural stem and progenitor cells (NSPCs), oligodendrocyte precursor cells (OPCs), olfactory ensheathing cells (OECs) and mesenchymal stem cells (MSCs).

Of particular interest was the sections on caveats for axon regeneration, noting that axon growth is not always associated with improved function. Little is known about how regenerating axons can be directed toward forming functional synapses with target neurons, given that robust axon regeneration remains a formidable challenge. It will be important to assess causal roles for specific populations of axons in recovery. Previously, it has not been possible to distinguish such causality and merely correlative evidence has been presented. With the development of reversible neuronal silencing technologies, it is now possible for researchers to assess the extent to which specific neuronal populations are incorporated into functional circuits.

3 Figures and 1 gigantic table on “Cell sources and proposed mechanisms of cited transplantation work”

Ropper AE, Ropper AH. Acute Spinal Cord Compression. N Engl J Med. 2017;376(14):1358-1369. doi:10.1056/NEJMra1516539.

Basic, but complete review of cord compression that should be mandatory reading for all radiology residents. This review covers both traumatic and non-traumatic cause of cord/cauda equine compression (tumor, infection, hematoma).

The cardinal features of acute spinal cord compression are relatively symmetric paralysis of the limbs, urinary retention or incontinence, and a circumferential boundary below which there is loss of sensation, referred to as the “sensory level”. Hyperreflexia and Babinski signs, which are characteristic of intrinsic diseases of the spinal cord, may not be evident in cases of acute and severe cord compression, particularly if the cause is trauma. The limbs may instead be flaccid and areflexic, accompanied by systemic hypotension — a combination of findings that constitutes the syndrome of spinal shock. Localized back or neck pain is an additional characteristic of most acute types of cord compression. Variations and partial presentations of the typical syndromes are common. The spinal cord ends near the L1–L2 level, where it transitions to spinal roots that make up the cauda equina. Acute compression of the cauda equina by lesions in the lumbar spine causes flaccid paraparesis and early incontinence, findings that are similar to those in patients with the syndrome of spinal shock.

Since cauda equina syndrome is a common diagnosis coming out of the ED for emergent lumbar spine MR, I thought I would call out those symptoms specifically:

1) Cauda equina syndrome (compression between L2 and S1 vertebral bodies)

2) Sciatic or other radicular pain

3) Areflexic weakness of feet and legs, depending on level of compression

4) Sphincter dysfunction

5) Reduced sensation from saddle region and legs up to groin

3 Figures, 3 Tables.

 

Journal Scan – This Month in Other Journals, August 2017
jross
Jeffrey Ross • Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.