NACC Vascular Consortium. NACC Vascular Consortium. NACC Vascular Consortium

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1 NACC Vascular Consortium NACC Vascular Consortium Participating centers: Oregon Health and Science University ADC Rush University ADC Mount Sinai School of Medicine ADC Boston University ADC In consultation with: Dr. Harry Vinters, UCLA ADC NACC Vascular Consortium Between the fall of 2000 and 2003, 4 meetings were held to discuss strategies for measuring vascular pathology and data collection. During this time, a total of 21 postmortem cases from four participating centers were analyzed by neuropathologists from each center, and the results of case analyses were reviewed. 1

2 NACC Vascular Consortium participants Neuropathologists: Dr. Melvin Ball - Oregon ADC Dr. Daniel Perl - Mount Sinai ADC Dr. Julie Snider - Rush ADC Dr. Ann McKee - Boston University ADC Study design and data review: Dr. Neil Kowall - Boston University ADC Dr. David Bennett - Rush ADC Dr. Roger Higdon - NACC Case Selection 21 cases encompassing a wide range of vascular pathology and severity of Alzheimer change were selected for analysis Cases with conflicting pathologies were excluded from the analysis, including: Parkinson s or Lewy Body Disease Frontotemporal degeneration Preparation of the tissue blocks Paraffin embedded blocks of formalin-fixed brain tissue were cut at 10 microns from 10 brain regions: 1. Middle frontal cortex (BA 9) 2. Inferior parietal cortex (BA 39,40) 3. Superior temporal cortex (BA 22) 4. Calcarine cortex (BA 17,18) 5. Anterior hippocampus 6. Hippocampus at level of the lateral geniculate nucleus 7. Amygdala and entorhinal cortex 8. Caudate, accumbens, putamen 9. Globus pallidus, putamen, nucleus basalis of Meynert 10. Anterior thalamus, level of anterior nucleus 2

3 Staining methods All sections were stained with luxol fast blue, hematoxylin and eosin or hematoxylin and eosin and luxol fast blue Sections of the amygdala, entorhinal cortex and hippocampus were stained with Bielschowsky silver method Sections from the cortex, amygdala, entorhinal cortex, globus pallidus and thalamus were immunostained with GFAP Cortical sections were also immunostained with amyloid beta protein Microscopic criteria 1. Fibrovascular hyalinosis Arteriolosclerosis / Lipohyalinosis hyaline thickening of arteriolar walls regions evaluated deep white matter of 4 cortical regions: middle frontal inferior parietal superior temporal calcarine cortices basal ganglia thalamus using the greatest degree of change found in a single vessel Microscopic criteria 1. Fibrovascular hyalinosis Arteriolosclerosis / Lipohyalinosis A rough guide: 1+ = increased wall thickness of 100% 2+ = 200% increase 3+ = 300% or greater increase in wall thickness, with progressive luminal narrowing. 3

4 Fibrovascular hyalinosis 0 1+ Myelin loss Judged by gross inspection of the luxol fast blue, hematoxylin and eosin stained slide and rated semi-quantitatively. Myelin loss was typically accompanied by loosening of tissue, loss of nerve fibers, and gliosis in the white matter. Myelin loss was designated diffuse if more than 50% of the white matter on the tissue section was affected in a evenly distributed single pattern, if less than 50% of the white matter was involved or if several disconnected areas were involved, the myelin loss was considered focal. If the area to be evaluated contained an infarct, the area was omitted from the analysis. Subcortical white matter myelin loss diffuse

5 Subcortical white matter myelin loss focal 0 1+ Dilation of perivascular spaces Evaluated in the subcortical white matter and in the basal ganglia using the greatest degree of dilation found around a single vessel seen in cross-section. Generally, a space approximately equal to the vascular lumen was considered 1+, twice the luminal diameter was measured as 2+ and three times the luminal diameter was judged to be 3+. Perivascular Spaces

6 Perivascular rarefaction Perivascular pallor of myelin staining or the degree to which the neuropil was attenuated or vacuolated around small blood vessels, was evaluated semiquantitatively in the subcortical white matter and in the basal ganglia. In the basal ganglia, perivascular rarefaction was often accompanied by perivascular dilation, a condition often referred to as cribriform state. If the cribriform changes were severe, it was occasionally difficult to distinguish from multiple areas of microinfarction. Perivascular Rarefaction 0 1+ Perivascular Rarefaction Basal Ganglia

7 Microinfarcts Basal Ganglia Microinfarcts Microinfarcts were defined as encephalomalacic lesions, 2 mm or smaller in greatest dimension, not identifable with certainty on gross inspection of the brain. In the cortex and subcortical white matter, cavitated and non-cavitated subacute, chronic microinfarcts and microhemorrhages were quantitated. Acute lesions characterized by zones of pallor and vacuolization with axon retraction balls, pyknotic neurons and no astrocytic or macrophage response were not included in the analysis. Microinfarcts Cavitated microinfarcts were defined as cystic areas of tissue loss or collapse with gliosis, and usually, macrophage infiltration. Non-cavitated microinfarcts were focal areas of cellular loss and gliosis without the formation of a cystic cavity, usually slit like or triangular in shape, devoid of neurons. Microscopic deposits of blood or hemosiderin with minimal evidence of ischemic infarction were designated as microhemorrhages. 7

8 Microinfarcts The number of microinfarcts and microhemorrhages were counted in 4 neocortical regions and underlying white matter, hippocampus, entorhinal cortex, and deep nuclei, including caudate, putamen, globus pallidus, thalamus, and amygdala. The number of microinfarcts and microhemorrhages were then recorded as score per region. Microinfarcts Cavitated Non-cavitated Perivascular macrophages 0 = no perivascular macrophages 1+ = 1-3 macrophages around a single small vessel 2+ = 4-8 macrophages 3+ > 9 macrophages 8

9 Vascular mineralization The degree of ferrruginization of small vessels of the globus pallidus was analyzed: 1+ = a thin rim of mineral, less than 1/2 the thickness of the vascular wall, around an occasional vessel 2+ = a rim of mineral generally equal to 1/2 the vascular wall thickness 3+ = the entire vascular wall of most vessels is mineralized 4+ in addition to replacement of most of the vascular wall with mineral, there are dense mineral deposits in capillaries and the parenchyma. Vascular Mineralization Globus pallidus Amyloid angiopathy The severity of amyloid angiopathy was evaluated in a manner modified from Von Sattel, Esiri, Vinters If no cerebral vessels showed immunopositivity for beta amyloid, the area was scored as 0. Amyloid restricted to a rim around smooth muscle fibers in the media of occasional normal vessels = 1+. If the media was thicker than normal and circumferentially replaced by amyloid in a few vessels = 2+. If there was widespread medial thickening and circumferential amyloid deposition with a small halo of immunoreactivity in the surrounding parenchyma = 3+. If the media was thickened by extensive amyloid deposition, the halo of parenchymal immunoreactivity was pronounced, there was a focus of wall leakage as evidenced by fresh hemorrhage or hemosiderin-laden macrophages, or occlusion, or recanalization = 4+. 9

10 Amyloid angiopathy NACC Vascular Consortium Data Collection Form The microscopic findings were entered into the NACC Vascular Consortium Dataset (hand-out) Proposed modfications: 1. Additional evaluation of pons and cerebellum for arteriolosclerosis and microinfarcts 2.Additional evaluation of Rolandic region for arteriolosclerosis, white matter changes and microinfarcts 3.Discontinuation of analysis for patchy gliosis due to the impracticality of additional immunostained sections and the variability of the GFAP stain. 4.Discontinuation the anterior hippocampal section as little supplementary information was obtained from analysis of 2 hippocampal regions. 10

11 Inter-rater reliability An analysis of an additional 12 cases is being undertaken to establish inter-rater reliability. 11