Journal Scan

Journal Scan – This Month in Other Journals, January 2017

Akoudad S, Wolters FJ, Viswanathan A, et al. Association of Cerebral Microbleeds With Cognitive Decline and Dementia. JAMA Neurol. 2016;73(8):934. doi:10.1001/jamaneurol.2016.1017.

The authors wanted to determine whether microbleed count and location were associated with an increased risk for cognitive impairment and dementia. They evaluated a prospective population-based study set in the general community, and assessed the presence, number, and location of microbleeds at baseline (August 2005 to December 2011) on brain MRI in 4841 participants 45 years or older. Trained research physicians, blinded to clinical data, reviewed the MRs. Cerebral microbleeds were defined as small, round to ovoid areas of focal signal loss on T2- weighted images. Participants underwent neuropsychological testing at 2 time points approximately 6 years apart, and were also followed up for incident dementia. 3257 participants underwent baseline and follow-up cognitive testing. Microbleed prevalence was 15.3%. The presence of more than 4 microbleeds was associated with cognitive decline. The presence of microbleeds was associated with an increased risk for dementia after adjustment for age, sex, and educational level, including Alzheimer dementia.

The strengths of this study, according to the authors, is the longitudinal population based design with a large sample size, the use of an extensive neuropsychological test battery, and the virtually complete screening for incident dementia. Limitations include multiple statistical tests, increasing the chance of type I errors. Second, selection bias may have influenced the results, because healthier people without subjective memory complaints were more likely to receive follow-up cognitive testing. Most importantly perhaps, the microbleed number may not reflect the true biological number because microbleed detection strongly depends on technical imaging methods used. T2W images were used, and as we know, SWI is far superior for the detection of these lesions.

4 Tables

Manoso MW, Moore TA, Agel J, Bellabarba C, Bransford RJ.

Journal Scan – This Month in Other Journals, December 2016

Austein F, Riedel C, Kerby T, et al. Comparison of Perfusion CT Software to Predict the Final Infarct Volume After Thrombectomy. Stroke. 2016 doi:10.1161/STROKEAHA.116.013147.

The purpose of the study was to determine the accuracy of different commercial perfusion CT software packages to predict the final infarct volume (FIV) after mechanical thrombectomy. Packages evaluated included 1) Philips Brain CT Perfusion Package, Philips Healthcare, The Netherlands, 2) Siemens (Syngo Volume Perfusion CT Neuro, Siemens Healthcare, Erlangen, Germany, and 3) RAPID (iSchemaView Inc, Menlo Park, CA). CTP data from 147 mechanically recanalized acute ischemic stroke patients were postprocessed. Ischemic core and final infarct volume were compared about thrombolysis in cerebral infarction (TICI) score and time interval to reperfusion. Final infarct volume was measured at follow-up imaging between days 1 and 8 after stroke. Significant differences were found between the packages about over- and underestimation of the ischemic core, with RAPID best-predicting hypoperfusion volume in nonsuccessfully recanalized patients. They conclude that this software package overestimated the final infarct volume to a significantly lower degree and estimated a malignant mismatch profile less often than other software.

Tan BYQ, Wan-Yee K, Paliwal P, et al. Good Intracranial Collaterals Trump Poor Alberta Stroke Program Early CT Score for Intravenous Thrombolysis in Anterior Circulation Acute Ischemic Stroke. Stroke. 2016 doi:10.1161/STROKEAHA.116.013879.

As a nice background and reference to describe the various collateral scoring systems, see: Yeo et al, Assessment of Intracranial Collaterals on CT Angiography in Anterior Circulation Acute Ischemic Stroke, AJNR 2015.

The authors evaluated the prognostic effect of the collateral circulation in patients with thrombolysed acute ischemic stroke who have large early infarct sizes as indicated by low ASPECTS score. They stratified patients using ASPECTS into 2 groups: large volume infarcts (ASPECTS≤ 7 points) and small volume infarcts (ASPECTS 8–10). They also evaluated a third group …

Journal Scan – This Month in Other Journals, November 2016

Saber H, Silver B, Santillan A, Azarpazhooh MR, Misra V, Behrouz R. Role of emergent chest radiography in evaluation of hyperacute stroke. Neurology. 2016;87(8):782–785. doi:10.1212/WNL.0000000000002964.

Despite evidence supporting the prompt administration of IV rtPA, fewer than one-third of acute ischemic stroke patients receive this medication within the target window of 60 minutes or less. Patient and technical factors often contribute to delays in the so-called door-to-needle time or the period from hospital presentation to initiation of treatment. Given this background, the authors compared features of patients who had a CXR done before IV thrombolytics with those who did not. Rates of cardiopulmonary adverse events, intubation, and in-hospital mortality were also compared. Logistic regression analysis was performed to evaluate the association of CXR performance with door-to-needle time greater than or equal to 60 minutes. In the cohort of 615 patients, 243 had CXR done before IV thrombolytics. Patients with CXR before treatment had significantly higher admission neurologic deficit and initial respiratory rates. Patients with CXR done before treatment had longer mean door-to-needle times than those without pretreatment radiography (75.8 vs 58.3 minutes). The performance of CXR before IV thrombolytics prolongs door-to-needle time in acute ischemic stroke patients. CXR before treatment should be reserved for situations wherein acute cardiopulmonary conditions would otherwise preclude the administration of IV thrombolytics.

Banwell B. Pediatric multiple sclerosis. Neurology. 2016;87(8):822–826. doi:10.1212/WNL.0000000000003014.

This is the 2015 Sydney Carter Award Lecture in which Dr. Banwell summarizes the learning curve and milestones achieved in pediatric multiple sclerosis care and research to date.

Dr. Banwell notes that the available MS diagnostic criteria proposed by Poser in 1983 specifically excluded the diagnosis of MS in persons younger than ten years, and did not formally comment on MS in youth. Further complicating the diagnosis and care of pediatric patients with MS is …

Journal Scan – This Month in Other Journals, October 2016

Mossa-Basha M, de Havenon A, Becker KJ, et al. Added Value of Vessel Wall Magnetic Resonance Imaging in the Differentiation of Moyamoya Vasculopathies in a Non-Asian Cohort. Stroke. 2016;47(7):1782–1788. doi:10.1161/STROKEAHA.116.013320.

Moyamoya vasculopathy is divided into moyamoya disease (MMD) and moyamoya syndrome (MMS). This is a steno-occlusive process of the carotid termini, proximal middle cerebral artery, and anterior cerebral artery with development of compensatory collaterals. If patients have a well-recognized associated condition, then it is called moyamoya syndrome, whereas those patients with no known associated risk factors are said to have moyamoya disease. By definition, the pathognomic arteriographic findings are bilateral in moyamoya disease (although severity can vary between sides). Patients with unilateral findings have moyamoya syndrome, even if they have no other associated risk factors. MMS may arise secondary to many underlying disease processes, including sickle cell anemia, NF1, radiation therapy, congenital syndromes, intracranial atherosclerotic disease (A-MMS), and vasculitis (V-MMS). Making a correct and specific diagnosis will alter management, since MMD is treated by surgical revascularization, whereas the SAMMPRIS trial showed that aggressive medical management is the first-line therapy for a patient with high-grade (70%–99%) atherosclerotic stenosis. In this study, 10 atherosclerotic disease related MMS patients, 3 vasculitis disease related MMS patients, and 8 moyamoya disease patients with 38 affected carotid segments were evaluated with vessel wall MR. The most common vessel wall MRI findings for moyamoya disease were nonenhancing, nonremodeling lesions without T2 heterogeneity; for A-MMS eccentric, remodeling, and T2 heterogeneous lesions with mild/moderate and homogeneous / heterogeneous enhancement; and for V-MMS concentric lesions with homogeneous, moderate enhancement. There was an 11% inter-reader agreement for diagnosis on luminal imaging when compared with 82% for luminal imaging + vessel wall MRI. They conclude that vessel wall MRI improves diagnostic accuracy and diagnostic confidence in the differentiation of MMD from …

Journal Scan – This Month in Other Journals, September 2016

Gondi V, Yock TI, Mehta MP. Proton therapy for paediatric CNS tumours — improving treatment-related outcomes. Nat Rev Neurol. 2016;12(6):334–345. doi:10.1038/nrneurol.2016.70.

In this review, the authors provide an introduction to the types of pediatric CNS tumors for which proton therapy can be considered, and discuss the evidence that proton therapy limits toxicities and improves quality of life for patients. As you no doubt remember from your residency, a proton has a defined maximum penetration depth, called the Bragg peak, at which the majority of its energy is released over a few millimeters. The Bragg peak is determined by the energy of a proton, and can be shortened to match the distal edge of the target by placement of customized tissue-equivalent material in the beam path. Before reaching the Bragg peak, a proton loses only a small amount of its energy, so delivers a lower ‘entrance’ dose than does conventional X‑ray therapy. Beyond the Bragg peak, a proton has no energy, so delivers no ‘exit’ dose. The improvement in dose distribution achieved with proton therapy can meaningfully affect the risk of long-term radiotherapy effects, such as secondary malignancy, cognitive toxicity, endocrinopathy, hearing loss and vasculopathic effects. Despite its higher up front costs, proton therapy has been shown to be more cost effective than X ray therapy owing to the dramatic reduction in the excess costs of managing long-term toxicities. Keep in mind that randomized trials of proton ther¬apy versus X ray therapy are unlikely due to the rarity of the diseases involved and the ethical issues surrounding the enrollment of children into trials in which one arm is asso¬ciated with a greater likelihood of toxicity. Uncertainty about the biological effects of proton therapy on certain healthy tissue and the relative inaccessibility of proton therapy, especially in developing nations, pose important …

Journal Scan – This Month in Other Journals, August 2016

Cavalcanti DD, Preul MC, Kalani MYS, Spetzler RF. Microsurgical anatomy of safe entry zones to the brainstem. J Neurosurg. 2016;124(5):1359–1376. doi:10.3171/2015.4.JNS141945.

In this image rich paper, the authors examined 13 safe entry zones on the brainstem (previously described in the literature) and used cadaveric dissections to evaluate the main surgical approaches currently employed to manage intrinsic brainstem lesions. Through dissection images of these approaches, they demonstrate what can be seen on the brainstem through each of these surgical corridors and delineate the safe entry zones provided by each approach.  The approaches described include three midbrain regions (anterior mesencephalic zone, lateral mesencephalic sulcus, intercollicular region), 6 pontine zones (peritrigeminal zone, supratrigeminal zone, lateral pontine zone, supracollicular zone, infracollicular zone, median sulcus of the fourth ventricle), and 4 medullary zones (anterolateral and posterior median sulci of the medulla, olivary zone, and lateral medullary zone). In addition to the surface anatomy, the paper describes the general surgical approaches to the regions, including Orbitozygomatic, Subtemporal, Subtemporal Transtentorial, Anterior Petrosectomy, Suboccipital Telovelar, Median Supracerebellar Infratentorial, Extreme Lateral Supracerebellar Infratentorial, Retrosigmoid, Far Lateral, and Retrolabyrinthine.

13 illustrations and 2 tables.

Close to all a Neuroradiologist needs to know about surgical approaches to the brainstem, and then some.

Drazin D, Nuño M, Patil CG, Yan K, Liu JC, Acosta FL. Emergency room resource utilization by patients with low-back pain. J Neurosurg Spine. 2016;24(5):686–693. doi:10.3171/2015.7.SPINE14133.

The authors conducted a retrospective analysis of patients with LBP discharged from hospitals according to the Nationwide Inpatient Sample (NIS) between 1998 and 2007. A majority (65%) of patients discharged from hospitals in the US from 1998 to 2007 with a primary diagnosis of LBP were admitted through the ER, with more patients being admitted via this route each year (183,151 patients). These patients were less likely to be discharged directly home …

Journal Scan – This Month in Other Journals, July 2016

 

  1. Anderson MA, Burda JE, Ren Y, et al. Astrocyte scar formation aids central nervous system axon regeneration. Nature. 2016;532(7598):195–200. doi:10.1038/nature17623.

This is an important paper to be aware of:  Astrocytic scars have been regarded as barriers to central nervous system axon regrowth since around 1952. Through an impressive set of experiments, the authors show that using three genetically targeted loss-of-function manipulations in adult mice that prevent scar formation or stop scar forming astrocytes all failed to result in spontaneous regrowth of transected corticospinal, sensory or serotonergic axons through severe spinal cord injury (SCI) lesions.  Specifically, they 1) prevented astrocyte scar formation, 2) attenuating scar-forming astrocytes, and 3) ablated chronic astrocytic scars (using genetically targeted diphtheria toxin receptor and ultra-low doses of diphtheria toxin). They conclude that these experiments show that contrary to the prevailing dogma, astrocytic scar formation is not a principal cause for the failure of injured mature CNS axons to regrow across severe CNS lesions.   In fact, scar-forming astrocytes permit and support robust amounts of appropriately stimulated CNS axon regeneration.  These findings have obvious important implications for CNS repair strategies.

  1. Liddelow SA, Barres BA. Regeneration: Not everything is scary about a glial scar. Nature. 2016;532(14 April):182–183. doi:10.1038/nature17318.

This is an Editorial that goes along with the previous paper by Anderson et al.  How do we reconcile previous experiments showing scar is bad with this current information?  One potential answer is that other inhibitory cell types such as fibroblasts and pericytes, also contribute to the glial scar.  Other studies have identified different types of reactive astrocyte. Perhaps in the previous studies different types of injury produced different types of reactive astrocyte, some being inhibitory and others not so much.  They conclude that “ in spite of long-held beliefs to the contrary, reactive astrocytes may not …

Journal Scan – This Month in Other Journals, June 2016

 

  1. Chen Z, Zheng Y, Yuan Y, et al. Modic Changes and Disc Degeneration Caused by Inoculation of Propionibacterium acnes inside Intervertebral Discs of Rabbits: A Pilot Study. Biomed Res Int. 2016;2016:9612437. doi:10.1155/2016/9612437.

Wild-type strain of P. acnes isolated from a patient associated with Modic change and disc degeneration was inoculated into the intervertebral discs of rabbits (n=8). S. aureus was injected into the discs to establish a model of discitis as a comparison.  A standard strain of P. acnes was inoculated as the control. MRI and histological change were evaluated. MRI was performed before and every two weeks after the inoculation until the end of follow-up at the eighth week. Both the P. acnes-inoculated and S. aureus-inoculated rabbits showed hyperintense signals at endplates and hypointense signals at nucleus pulposus on T2WI. However, P. acnes only resulted in moderate disc degeneration and endplates rupture in histological examination. They conclude that compared to S. aureus, the pathological change caused by P. acnes would be considered as Modic-I change and disc degeneration rather than a discitis.

They are of the opinion that the presented data satisfied the first, second, and third criteria of Koch’s Postulates and they extrapolate that P. acnes has a strong connection with Modic change and disc degeneration. 3 figures with histopathology.

In case you had forgotten Koch’s postulates:

  1. The pathogen must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms.
  2. The pathogen must be isolated from a diseased host and grown in pure culture.
  3. The cultured microorganism should cause the disease when introduced into a healthy organism.
  4. The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
  1. Hall SS, Dougherty RF, Reiss AL. Profiles

Journal Scan – This Month in Other Journals, May 2016

  1. Safain MG, Roguski M, Heller RS, Malek AM. Flow Diverter Therapy With the Pipeline Embolization Device Is Associated With an Elevated Rate of Delayed Fluid-Attenuated Inversion Recovery Lesions. Stroke. 2016;47(3):789–97. doi:10.1161/STROKEAHA.115.010522.

Forty-one consecutive patients undergoing aneurysm treatment with the Pipeline Embolization Device and a comparison group of 78 Neuroform stent-mediated embolizations were studied. Serial magnetic resonance images were assessed for the presence of newly occurring diffusion-weighted imaging and fluid-attenuated inversion recovery (FLAIR) lesions. Pipeline patients were more likely to have new ipsilateral FLAIR lesions at all time points studied, and 34% (14/41) of Pipeline patients experienced a new FLAIR lesion when compared with 10% (8/78) of Neuroform stent-coil patients. No patient in either group developed a new permanent neurological deficit. They conclude that PED is associated with continued new and independent ipsilateral FLAIR signal abnormalities, and that these lesions were independent from any previous DWI or FLAIR lesion, suggesting a persistent delayed and de novo source generation process. This was in stark contrast with Neuroform-stent–assisted coil embolization, which had almost no rat new FLAIR burden.

Worrisome……prudent follow up recommended!

  1. Auriel E, Charidimou A, Gurol ME, et al. Validation of Clinicoradiological Criteria for the Diagnosis of Cerebral Amyloid Angiopathy-Related Inflammation. JAMA Neurol. 2016;73(2):197–202. doi:10.1001/jamaneurol.2015.4078.

They modified the previously proposed clinicoradiological criteria and retrospectively analyzed clinical medical records and FLAIR and gradient-echo scans obtained from individuals with CAA-ri and noninflammatory CAA at two referral centers. Participants included 17 individuals with pathologically confirmed CAA-ri and 37 control group members with pathologically confirmed noninflammatory CAA. In the CAA-ri group, 14 of 17 (82%) met the criteria for both probable and possible CAA-ri. Sensitivity and specificity was 82%and 97%, respectively, for the probable criteria and sensitivity and specificity of 82%and 68%, respectively, for the possible criteria.

Their findings also indicate that small DWI hyperintense …

Journal Scan – This Month in Other Journals, April 2016

 

  1. Benarroch EE. Choroid plexus-CSF system: Recent developments and clinical correlations. Neurology. 2016;86(3):286–96. doi:10.1212/WNL.0000000000002298.

Excellent comprehensive review of the role and function of the choroid plexus in health and disease.  2 Tables and 1 graphic.

Fun facts you have learned, and then probably forgotten. I sure have.

-80% of CSF is secreted by the choroid plexus (20% from brain interstitial space)

-Choroid plexus secretes CSF at a rate of 0.4 mL/min/g of tissue

-500 cc per day

-Total volume of 150cc, so the CSF exchanges 3-4X per day

-Main determinants of CSF secretion are the active secretion of Na+ via the Na+-K+ ATPase and the production of bicarbonate by action of carbonic anhydrase in choroid epithelial cells

– Three parts of the glymphatic system: 1) para-arterial CSF influx; 2) paravenous interstitial fluid clearance route; 3) transparenchymal pathway depending on astroglial water transport via AQP4 channels

-Glymphatic system estimated to remove 40%–80% of solutes and proteins, including amyloid-beta peptide and tau, from the superficial cerebral cortex

  1. Cui Z, Pan L, Song H, et al. Intraoperative MRI for optimizing electrode placement for deep brain stimulation of the subthalamic nucleus in Parkinson disease. J Neurosurg. 2016;124(1):62–69. doi:10.3171/2015.1.JNS141534.

The authors note that various methods have been used to localize the subthalamic nucleus (STN), including MRI, brain atlas–imaging fusion for preoperative planning, intraoperative microelectrode recording (MER), intraoperative MRI (iMRI), temporary efficacy during the operation, postoperative MRI, and sustained effect during the postoperative period.  In this study, 206 DBS electrodes were implanted in the STN in 110 patients with Parkinson disease. All patients underwent intraoperative MRI after implantation to define the accuracy of lead placement. Fifty-six DBS electrode positions in 35 patients deviated from the center of the STN, according to the result of the initial post-placement iMRI scans. …