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 A-MMS and V-MMS compared with luminal imaging alone. 4 Tables and 1 Figure showing the typical findings for MMD, A-MMS and V-MMS.
See also: Intracranial Vessel Wall MRI: Principles and Expert Consensus Recommendations of the American Society of Neuroradiology. AJNR Am J Neuroradiol. Published online on July 28, 2016, 10.3174/ajnr.A4893.
Birkeland P, Gardner K, Kesse-Adu R, et al. Intracranial Aneurysms in Sickle-Cell Disease Are Associated With the Hemoglobin SS Genotype But Not With Moyamoya Syndrome. Stroke. 2016;47(7):1710–1713. doi:10.1161/STROKEAHA.116.012664.
While there are several case reports describing intracranial aneurysms and aneurysmal subarachnoid hemorrhage (SAH) and its management in patients with sickle-cell disease (SCD), the prevalence of intracranial aneurysms and incidence of aneurysmal SAH in the sickle-cell population remains unclear. The authors retrospectively evaluated the records from a total of 1002 patients with SCD attending 2 specialized adult hematologic services. Unruptured intracranial aneurysms were found in 20 of the 324 patients, who had imaging data; the prevalence was significantly higher in patients with HbSS genotype compared with other sickle genotypes with the highest prevalence (15%) observed in women in the age group 30 to 39 years. They conclude that intracranial aneurysms are common in HbSS SCD. There was also a trend toward more common occurrence of aneurysmal SAH in HbSS; women in the age group 30 to 39 years were most at risk. They found no correlation between the occurrence of intracranial aneurysms and moyamoya syndrome.
Hardy TA, Reddel SW, Barnett MH, Palace J, Lucchinetti CF, Weinshenker BG. Atypical inflammatory demyelinating syndromes of the CNS. Lancet Neurol. 2016;15(9):967–981. doi:10.1016/S1474-4422(16)30043-6.
This is an excellent review article on the “other” demyelinating syndromes. Multiple sclerosis a general term applied to patients who present with clinical syndromes compatible with inflammatory demyelination and MR findings that satisfy the principle of dissemination in space and time. This review article discusses neuromyelitis optica spectrum disorder, acute disseminated encephalomyelitis, tumefactive demyelination, Balo’s concentric sclerosis, Schilder’s disease (Schilder’s diffuse myelinoclastic sclerosis), and Marburg’s multiple sclerosis. Neuromyelitis optica spectrum disorders (the preferred terminology rather than just neuromyelitis optica or Devic’s) are now recognized as being distinct from multiple sclerosis, with a specific target antigen (aquaporin-4 [AQP4]) and is more properly defined by immunopathological studies as an inflammatory astrocytopathies rather than as a primary demyelinating disease. The hallmark clinical features of neuromyelitis optica spectrum disorders are optic neuritis, which is often bilateral or sequential, and longitudinal transverse myelitis that typically affects three or more vertebral segments. Almost a quarter of patients with neuromyelitis optica spectrum disorders who are seronegative for AQP4-IgG are seropositive for antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG), constituting around 5–10% of all patients. MOG-IgG is relatively more common in children than in adults with acquired demyelinating disease, and, when detected, is predictive of an atypical demyelinating syndrome. Brain lesions most often occur in the diencephalon around the third ventricle, around the cerebral aqueduct, and in the thalamus, hypothalamus, and anterior midbrain, but are also frequently found in the dorsal brainstem, including the area postrema. ADEM is an uncommon, usually multifocal, demyelinating disorder of the CNS that generally affects children but occurs rarely in adults. Neurological deficits reflect the locations of the lesions but, unlike in multiple sclerosis, encephalopathy is frequent and sometimes associated with seizures. Typically, symptoms of acute disseminated encephalomyelitis evolve rapidly, often with fever and occasionally meningismus. Acute hemorrhagic leukoencephalitis, also known as Hurst’s acute necrotizing hemorrhagic leukoencephalitis or Hurst’s disease, is a very rare form of demyelinating disease that is thought to be a fulminant hemorrhagic form of ADEM. Tumefactive demyelination is a term imprecisely applied to demyelinating lesions larger than 2 cm in diameter. It is characterized by cerebral mass lesions, and symptoms include seizures, impaired consciousness, cognitive deficits, and focal neurological signs. Schilder’s disease is said to be a rare demyelinating disease seen most frequently in children. Whether it is distinct from other atypical demyelinating syndromes remains very unclear. Marburg’s variant of multiple sclerosis is an acute fulminant form of demyelinating disease that was first described in 1906. Patients typically present with seizures, headache, vomiting, bilateral optic neuritis, and gait disturbance with hemiparesis or quadriparesis.
5 Figures
Topcuoglu MA, Singhal AB. Hemorrhagic Reversible Cerebral Vasoconstriction Syndrome. Stroke. 2016;47(7):1742–1747. doi:10.1161/STROKEAHA.116.013136.
Reversible cerebral vasoconstriction syndrome (RCVS) is well characterized as a group of conditions typically heralded by severe thunderclap headaches (TCH) and associated with reversible segmental multifocal cerebral artery vasoconstriction. Approximately one third to half develop intracerebral hemorrhage (ICH), convexal subarachnoid hemorrhage (cSAH), ischemic stroke, and PRES, either alone or in combination. The authors performed a single-center retrospective study of 162 patients with RCVS. Clinical, brain imaging, and angiography data were analyzed comparing hemorrhagic and nonhemorrhagic forms. Hemorrhages occurred in 43% including 21 patients with intracerebral hemorrhage (ICH) and 62 with convexal subarachnoid hemorrhage (cSAH). The frequency of triggers (eg, vasoconstrictive drugs) and risk factors (eg, migraine) were not significantly different between hemorrhagic and nonhemorrhagic RCVS or between subgroups. Hemorrhagic lesions occurred within the first week. They conclude that ICH and convexal subarachnoid hemorrhage are common complications of RCVS. Triggers and risk factors do not predict lesion subtype.
2 Figures, 2 Tables
Much higher rate of intracranial hemorrhage than I thought.
Honeybul S, Ho KM, Blacker DW. ORACLE Stroke Study. Neurosurgery. 2016;79(2):231–236. doi:10.1227/NEU.0000000000001115.
For your information and reference, the modified Rankin score (mRS):
0 – No symptoms.
1 – No significant disability. Able to carry out all usual activities, despite some symptoms.
2- Slight disability. Able to look after own affairs without assistance, but unable to carry out all previous activities.
3 – Moderate disability. Requires some help, but able to walk unassisted.
4 – Moderately severe disability. Unable to attend to own bodily needs without assistance, and unable to walk unassisted.
5 – Severe disability. Requires constant nursing care and attention, bedridden, incontinent.
The authors assessed the opinion on consent and acceptable outcome among a wide range of healthcare workers regarding the use of decompressive hemicraniectomy in the management of malignant cerebral artery infarction. Seven hundred seventy-three healthcare workers at the 2 major public neurosurgical centers in Western Australia participated. Participants were asked to record their opinion on consent and acceptable outcome based on the modified Rankin Score (mRS). 52.7% initially felt that they would provide consent for a decompressive craniectomy as a lifesaving procedure, but only a minority of them considered an mRS score of 4 or 5 an acceptable outcome (moderately severe or severe disability). Participants were also presented with a description of the disability paradox; that is when people (especially doctors) often overestimate the emotional impact of chronic illness and disability. After the introduction of the concept of the disability paradox and the evidence for the clinical efficacy of decompressive craniectomy, more participants were unwilling to accept decompressive craniectomy (18.1% vs 37.8%), but at the same time, more were willing to accept an mRS score <4 as an acceptable outcome. Decompressive hemicraniectomy represents a lifesaving intervention for patients who develop malignant middle cerebral artery infarction. However, it is becoming increasingly apparent that outcome cannot be dichotomized into life or death because doing so would fail to recognize that in many cases, especially for patients >60 years of age, the most likely outcome is dependency with significant neurocognitive disability. Informed consent must involve a detailed exploration of the acceptability (or otherwise) of this outcome.
See also: Hutchinson PJ, Kolias AG, Timofeev IS, et al. Trial of Decompressive Craniectomy for Traumatic Intracranial Hypertension. N Engl J Med. 2016;375(12):1119-1130. doi:10.1056/NEJMoa1605215.
Ioannidis JPA, Klavans R, Boyack KW. Multiple Citation Indicators and Their Composite across Scientific Disciplines. Amaral LAN, ed. PLOS Biol. 2016;14(7):e1002501. doi:10.1371/journal.pbio.1002501.
Who is the best scientist, and how do you determine that? Many fields face an increasing prevalence of multi-authorship, and this poses challenges in assessing citation metrics. The authors explored multiple citation indicators that address total impact (number of citations, Hirsch index), co-authorship adjustment (Schreiber index), and author order (total citations to papers as single; single or first; or single, first, or last author). The authors demonstrate the correlation patterns between these indicators across 84,116 scientists. They propose a composite score that sums standardized values of these six log-transformed indicators (total number of citations received in 2013, total number of citations received in 2013 to papers for which the scientist is single author, total number of citations received in 2013 to papers for which the scientist is single or first author, total number of citations received in 2013 to papers for which the scientist is single, first, or last author, Hirsch H index for the citations received in 2013, and Schreiber co-authorship adjusted index for the citations received in 2013).
Of the 1,000 top-ranked scientists with the composite score, only 322 are in the top 1,000 based on total citations! Many Nobel laureates and other influential scientists rank among the top-1,000 with the composite indicator, but would rank much lower based on total citations. Conversely, many of the top 1,000 authors on total citations have had no single/first/last-authored cited paper. Instead of using only one citation indicator, systematically examining multiple indicators offers a more complete, granular picture.
Typical quality vs. quantity dichotomy
Taurog JD, Chhabra A, Colbert RA. Ankylosing Spondylitis and Axial Spondyloarthritis. N Engl J Med. 2016;374(26):2563–2574. doi:10.1056/NEJMra1406182.
This is a comprehensive review article on ankylosing spondylitis (AS) and axial spondyloarthritis. Spondyloarthritis is marked by enthesitis and by synovitis and osteitis. The enthesis has been conceptualized as an organ that comprises the ligamentous or tendinous insertion site itself along with adjacent tendon and the fibrocartilage, fat pad, bursa, and synovium, the primary purpose of which is to dissipate mechanical stress. Although the basic trigger for the inflammation of spondyloarthritis remains unknown, several lines of evidence implicate the cells and molecules in the pathway involving interleukin-23 and interleukin-17.
The Assessment of SpondyloArthritis International Society (ASAS) criteria for the diagnosis of axial spondyloarthritis requires the presence of subchondral or periarticular bone marrow edema in sacroiliac joints (in plane resolution of 0.4 to 0.6 mm, with slice thickness of 3 to 4 mm) on fat-saturated, T2 -weighted or short-tau inversion recovery (STIR) sequences, with two or more lesions visible on one slice or a single lesion visible on two or more consecutive slices. The appearance of erosion of the sacroiliac joint on T1 -weighted spin-echo sequencing adds sensitivity. Bone marrow edema in the sacrum alone or in both the sacrum and the ilium is an independent predictor of spondyloarthritis.
3 Figures, 2 Tables
Murchison EP. Cancer: Transmissible tumours under the sea. Nature. 2016. doi:10.1038/nature18455.
Now for something completely different. This is an editorial in Nature on the Metzger et al. report (Metzger MJ, Villalba A, Carballal MJ, et al. Widespread transmission of independent cancer lineages within multiple bivalve species. Nature. 2016:1–11. doi:10.1038/nature18599) of the discovery that transmissible cancers are widespread in one group of marine shellfish, and that such cancers can jump between species. These findings suggest that cancer cells are common infectious agents in marine environments, and challenge our understanding of the nature of cancer and its interaction with its hosts. Until this latest report, transmissible can¬cers — cancer-cell lineages with the potential to metastasize through an animal popula¬tion — were considered to be exceedingly rare. Only four examples were known in nature: two affecting Tasmanian devils, one in dogs and another in soft-shell clams. Metzger and co-workers now report four previously uniden¬tified transmissible cancers: one that affects mussels (Mytilus trossulus) found in British Columbia, one that affects golden carpet shell clams (Polititapes aureus) on the Iberian coast and two transmissible cancers of prob¬ably independent origin in common cockles (Cerastoderma edule). These cancers all cause a leukemia-like disease in affected individuals called dissemi¬nated neoplasia. One particularly interesting and unexpected finding of Metzger and colleagues’ work was that DNA extracted from cancer cells in golden carpet shell clams showed no genetic match with normal DNA from this species, but instead indicated that the cancer cells originated in a different species — the pullet shell clam. Even more strange is that the pullet shell clams — which share a habitat with golden carpet shell clams — are not known to have a high prevalence of disseminated neoplasia. Perhaps the pullet shell clam has adapted to resist infection by the transmissible cancer. These findings seem to paint a picture of shellfish beds around the world that are awash with microscopic cancer cells metastasizing both within and between species.
Bet you did not think we would be discussing the pullet shell clam!
