Neurodegenerative diseases

From Libre Pathology
Jump to navigation Jump to search

Neurodegenerative diseases is a big part of neuropathology. It includes some discussion of dementia.

Overview

  • Neurodegenerative disease = essentially progressive and selective neuron loss.
  • Clinically, they are not unique, e.g. dementia can be caused by several diseases (with different molecular etiologies).
    • Each syndrome (e.g. dementia, parkinsonism, ataxia) has a most common etiology and a DDx.
  • They are defined by molecular pathology.[1]
    • The diseases are due to the accumulation of abnormal protein.
      • The amino acid sequence of the protein may be completely normal. The problem may just be folding/protein conformation.

Molecular schema of neurodegenerative disorders:[1]

 
 
 
 
 
 
Neurodegenerative
disorders
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Amyloidoses
 
Tauopathies
 
α-synucleinopathies
 
TDP-43
 

Common diseases

Amyloidoses:

  • Alzheimer disease (Abeta).

'Pure' tauopathies:

Synucleinopathies:[2]

TDP-43 proteinopathies:

FUS proteinopathies:

Prionopathies:

  • Creutzfeldt-Jakob disease (PrP).

Table

Disease/pathology/clinical correlation based on Dickson:[1]

Disease Mutated protein Distribution Clinical Histology Image
Alzheimer disease Abeta (mutated APP) corticolimbic, usu.
spares occipital
dementia plaques, neurofibrillary tangles [1]
Creutzfeldt-Jakob disease PrPres (mutated PrP) cortical & basal ganglia dementia (rapid progression),
movement disorder
cytoplasmic vacuolization, PrP+ve plaques, Kuru plaques (MV2 variant) [2]
Parkinson disease alpha-synuclein brainstem parkinsonism Lewy bodies in substantia nigra and locus coeruleus [3] [4]
Dementia with
Lewy bodies
alpha-synuclein corticolimbic, brainstem dementia + parkinsonism Lewy bodies brainstem and cortical, tangles [5] [6]
Multiple system atrophy alpha-synuclein basal ganglia, brainstem, cerebellum parkinsonism, ataxia Papp-Lantos inclusions (cytoplasmic deposits in oligodendrocytes)[3] [7]
Amyotrophic lateral
sclerosis (ALS)
TDP-43 motor neurons spasticity, weakness motor neuron loss, TDP-43+ve, TAF15-ve, EWS-ve inclusions in motor neurons [8]
Frontotemporal lobar
degeneration with TDP-43 (FTLD-TDP)
TDP-43 cortex, basal ganglia dementia, focal cortical syndromes histology depends on (type 1-4), ubiquitin and TDP-43+ve, tau and FUS-ve [9]
Frontotemporal lobar
degeneration with FUS (FTLD-FUS)
FUS cortex, medulla, hippocampus, and motor cells of the spinal cord dementia, cases classified as FTLD-U, NIFID and BIBD FUS+ve, TAF15+ve, EWS+ve cytoplasmic & intranuclear inclusions, neuritic threads [10]
Progressive supranuclear palsy (FTLD-tau) tau 4R basal ganglia, brainstem atypical parkinsonism with early gait instability, falls, and supranuclear gaze palsy tau-positive globose neurofibrillary tangles
in neurons, tufted astrocytes, coiled bodies
in oligodendrocytes
[11]
Pick disease (FTLD-tau) tau 3R corticolimbic dementia + focal
cortical syndrome
Intraneuronal argyrophilic inclusions (Pick body) [12]
Corticobasal degeneration (CBD) (FTLD-tau) tau 4R cortical, basal ganglia dementia + movement disorder (Parkinson-plus syndrome) ballooned neurons, astrocytic plaques, pretangles in basal nucleus [13]
Argryophilic grain disease (AGD) (FTLD-tau) tau 4R medial temporal lobe, limbic structures late-onset amnestic syndrome Argyrophilic grains (also found unspecific in elederly) [14]

Immunohistochemistry

Alpha-synuclein

Look for:

  • Lewy bodies (seen in Parkinson's d., Dementia with Lewy bodies) = round cytoplasmic eosinophilic body +/- pale halo.

Tau

  • AT8 = stains phosphorylated tau.[4]
    • AT = anti-tau.
    • Stains tau 4R and tau 3R.[5]

TDP-43

  • May accumulate due to a progranulin mutation.

Microscopic

Ubiquitin

  • Marks proteins for recycling.

Microscopic

  • p62; poli-ubiquitin-binding protein p62.[4]

Look for:

  • Lewy bodies. (???)

Clinical perspective

Dementia general (mostly useless) DDx

  • Alzheimer's dementia - most common.
  • Vascular.
    • Multi-infarct dementia.
  • Parkinson's associated dementia.
  • Lewy body dementia.
  • Alcohol-related dementia.
  • Fronto-temporal dementia (Pick disease).
  • Multisystem atrophy.

Mnemonic

Dementia mnemonic VITAMIN D VEST:[8]

  • Vitamin deficiency (B12, folate, thiamine).
  • Infection (HIV).
  • Trauma.
  • Anoxia.
  • Metabolic (Diabetes).
  • Intracranial tumour.
  • Normal pressure hydrocephalus.
  • Degenerative (Alzheimer's, Huntington's, CJD).
  • Vascular.
  • Endocrine.
  • Space occupying lesion (chronic subdural hematoma).
  • Toxins (alcohol).

Functional anatomy of dementia

  • Hippocampus (essential for forming new memories).
  • Frontal lobe (essential for retrieval of memories).

Parkinsonism causes

Amyloidoses

Alzheimer disease

General

  • Onset: episodic memory loss.
  • Diagnosis is clinical & pathologic.
    • Pathologic finding alone are not diagnostic.
  • Seen in conjunction with vascular amyloid deposition; see cerebral amyloid angiopathy.

Genetics

Genes associated with Alzheimer disease:[13]

  • Amyloid precursor protein (APP).
    • On chromosome 21 - may explain why Trisomy 21 (Down syndrome) increases the risk of Alzheimer disease.[14]
  • Presenilin 1 (PSEN1).[15]
  • Presenilin 2 (PSEN2).[16]
  • Apolipoprotein E (APOE)[17] - specifically the epsilon-4 allele.

Gross

Features:

  • Temporal atrophy, esp. hippocampus.
  • Dilation of:
    • Lateral ventricles.
    • Third ventricle.

Gross/microscopic - disease spread by NF tangles (staging):[18]

  • Alzheimer "spreads" in a reproducible pattern:
    • Stage I-II: entorhinal cortex.
    • Stage III-IV: inferior aspect of brain.
    • Stage V-VI: limbic system.

Minimal sampling:

  • Frontal, parietal & temporal lobe
  • Hippocampus and entorhinal cortex

Additional sampling:

  • Basal ganglia
  • Cerebellum
  • Midbrain (including substantia nigra)
  • Occipital cortex

Images

Microscopic

Features:

  1. Neurofibrillary tangles.
  2. Senile plaques (AKA neuritic plaques).
    • Consists of two components:
      1. Centre - radiates.
        • Consists of Abeta amyloid
      2. Neurites - swollen axons.
    • Considered to be more specific for Alzheimer's than NF tangles.
      • How to remember: senile plaques = specific.
    • There is a CERAD staging system for senile plaque load: 0 (none), I (mild), II (moderate), III (severe).[23]
    • Images: senile plaques (utah.edu)[24] senile plaques - beta-APP - high mag. (WC).
  3. Neuron loss.
  4. +/-Cerebral amyloid angiopathy.

Images

Classification

NIA/AA Guidelines: "ABC" scoring method [25]

  • (A) assessment of amyloid b deposits
  • (B) staging of neurofibrillary tangles
  • (C) scoring of neuritic plaques
(A) abeta plaques (Thal phase)[26] (B) Neurofibrillary tangles (Braak stage) [27] (C) neuritic plaques (CERAD) [28]
(A0) 0 (B0) 0 (C0) none
(A1) 1 (temporal),2 (+frontal, +CA1) (B1) I,II (transentorhinal) (C1) sparse (1–5 neuritic plaques/1 mm2)
(A2) 3 (+diencephalon, +striatum) (B2) III,IV (limbic) (C2) moderate(6–19 neuritic plaques/1 mm2)
(A3) 4 (+brainstem),5 (+cerebellum, +pons) (B3) V,VI (neocortical) (C3) frequent(>20 neuritic plaques/1 mm2)

The ABC score is a good indicator for the likelihood of dementia.

Example: Cerebellar abeta deposits (A3) + tangles in entorhinal cortex and few temporal (B2), + 15 neuritic plaques per 1 mm2 (C2) -> (A3, B3, C2): intermediate AD level change.

Notes:

  • Abeta amyloid:
    • Derived from amyloid precursor protein (APP).
      • APP:
        • Rapid axonal transport - useful as a marker of axonal injury.
        • Function currently not known.
  • Tau:
    • Important in microtubule assembly.

Prion diseases

General

Etiology:[29]

  • Misfolded cell-surface protein called PrPSC.
    • This is derived from the protein PrPC encoded by the PRNP gene.

Includes:

  • Creutzfeldt-Jakob disease (CJD).
  • Sporadic fatal insomnia (sFI).[29]
  • Fatal familial insomnia (FFI).[30][31]
  • Gestmann-Straussler-Scheinker syndrome (GSS) - due to PRNP gene mutations.[32]

IHC

PrPC:[30]

  • Congo red +ve.
  • PAS +ve.

Creutzfeldt-Jakob disease

  • Commonly abbreviated as CJD.

General

  • Rare.
  • Incurable disease.

Usually diagnosed clinically:

  • Characteristic findings:
    • Very rapid decline (3-4 months).
    • Characteristic (cortex findings on) neuroradiology.

Variant Creutzfeldt-Jakob disease

  • Abbreviated vCJD.
General
  • Associated with bovine spongiform encephalopathy (AKA mad cow disease).
  • Should sample: spleen, lymph nodes, tonsils.[33]

Microscopic

Features:

  • Spongy appearance (cytoplasmic vacuolization[34]).

Note:

Images

Alpha-synucleinopathies

Includes the Lewy body diseases Parkinson's disease and Dementia with Lewy bodies.

Dementia with Lewy bodies

General

Clinical features:

  • Parkinsonian features.
  • Hallucinations (visual).
  • Progressive cognitive decline with fluctuations.

Microscopic

Features:

IHC

  • Alpha-synuclein +ve.

Parkinson disease

General

  • Common - often sporadic.
  • May be genetic.

Clinical TRAP:[36]

  • Tremor.
  • Rigidity.
  • Akinesia.
  • Postural instability.

Genetics:[37]

  • LRRK2 gene[38] - autosomal dominant.
  • PARK2 gene (parkin)[39] - autosomal recessive.

Gross

Features:[40]

  • Abnormally pale substantia nigra.
    • Pigmentation increases with age.
  • Pale locus ceruleus.

Notes:

Microscopic

Features:[40]

  • Loss of pigmented (catecholaminergic) neurons in the substantia nigra and locus ceruleus.
  • Gliosis - due to neuron loss.
  • Lewy bodies (in remaining neurons) - key feature.
    • Eosinophilic cytoplasmic inclusion with "dense" (darker) core and pale (surrounding) halo.
      • Consist of filaments composed of alpha-synuclein.

IHC

  • Alpha-synuclein +ve.

Multiple system atrophy

Multiple system atrophy is a neurodegenerative disease of the parkinsonism-plus disorder group.

General

Clinical findings variable:

  • Parkinsonism (stiatonigral degeneration, MSA-P).
  • Ataxia (olivo-ponto-cerebellar degeneration, MSA-C).
  • Autonomic dysfunction (Shy-Drager syndrome, depreceated).
  • Clinical onset between 40-60 years.
  • Progedient tremor, atxia, laryngeal paresis, wakness, cognitive decline.
  • Patients usually succumb after 6 years from aspiration pneumonia.

DDx:

Macroscopy

Microscopic

Features:

  • Inclusions cerebral, subcortical white matter, cerebellar.
  • Neuronal loss and gliosis.
  • Alpha-synuclein-rich glial and neuronal cytoplasmic inclusions (finding at autopsy).[41]
    • Inclusions in oligodendrocytes.[42]
  • Pons and Putamen:
    • Nuclear inclusions (sparse in most cases).
    • Neuropil threads (alpha-synuclein).
  • Loss of myelinated fibers from external capsule, striatum and pallidum.

Images

Molecular

  • No known alpha-synuclein mutation.
  • Genetic variants of SNCA gene assoicated with MSA. [43]

Tauopathies

Progressive supranuclear palsy

  • Commonly abbreviated PSP.
  • AKA Steele-Richardson-Olszewski syndrome.

General

  • Diagnosis - clinical.[44]

Clinical:

  • Impaired control of gaze, esp. difficulty looking up and down (supranuclear palsy).[45]
  • Parkinsonism.[11]

Microscopic

Features:[1][44][46]

  • Globose neurofibrillary tangles in neurons.
  • Coiled bodies in oligodendrocytes.
    • Wire coil-like structure around the nucleus.
  • Tufted astrocytes.
    • Near impossible to see without IHC - specifically AT8.
    • Cellular processes filled with crap.
    • Star-like appearance; looks like a road network where all the roads lead to one place (Parisian star).
  • Grumose degeneration of the cerebellar dentate nucleus.
    • Granular eosinophilic material adjacent to nuclei; once thought to be pathognomonic for PSP.[47][48]

Images:

Pick disease

General

  • Dementia.

Gross

  • Frontal and temporal lobe atrophy.[49]
    • May be called "walnut brain"[50] - as it resembles a walnut.

Microscopic

Features:[49]

  • Pick cells = large ballooned neurons.
  • Pick bodies = round, homogenous, intracytoplasmic inclusions, size ~10 micrometers.

Image(s):

Other

Chronic traumatic encephalopathy

  • Abbreviated CTE.

Huntington disease

General

  • Autosomal dominant inheritance.
  • Mutation in Huntington gene (HTT):[52]
    • 11-34 CAG repeat = normal.[53]
    • >42 CAG repeat = Huntington disease.

Clinical:[54]

  • Early onset dementia.
  • Involuntary movements (chorea) - both arms and legs.
  • Behaviour changes, e.g. grimacing.
  • Speech changes.

Gross

  • Severe caudate atrophy.[55]
    • Prominent frontal horns of the lateral ventricles.[56]

Note:

  • A normal caudate bulges into the ventricle.

Images:

Microscopic

Features:[54]

  • Neuron loss.
  • Gliosis.

Binswanger disease

General

  • Multi-infarct dementia affecting subcortical white matter.
  • Waste-basket diagnosis; diagnosed if CADASIL and amyloidosis have been excluded.
  • Diagnosis has been controversial -- most with this entity (in the past) were diagnosed with Alzheimer's disease.

Microscopic

Features:

  • Subcortical lesions that replace the myelin consisting of macrophages.

Frontotemporal lobar degeneration with ubiquitinated inclusions

Abbreviated FTLD with ubiquitinated inclusions or FTLD-TDP43.

General

  • There are several forms of frontotemporal dementia.
  • Related to amyotrophic lateral sclerosis (ALS); also a TDP-43 pathology.[57]
    • There are several subtypes of FTLD with TDP-43.

Gross

  • Frontal and temporal lobe atrophy.

Image:

Amyotrophic lateral sclerosis

  • Abbreviated ALS.

General

  • AKA Lou Gehrig's disease.
  • TDP-43 proteinopathy.
  • Characterized by motor neuron death.
  • May be familial and associated with SOD1 gene.[58]

Clinical:

  • Weakness.

Microscopic

Features:[58]

  • Motor neurons with Bunina bodies.
    • PAS positive cytoplasmic inclusions.
  • Motor neuron loss + reactive gliosis + neurogenic muscular atrophy.

Images:

Hallervorden-Spatz disease

  • AKA pantothenate kinase-associated neurodegeneration.

General

  • Uncommon.

Microscopic

Features:[60]

  • Axonal spheroids.
  • Iron deposition.

Images:

Stains

  • Prussian blue +ve.

See also

References

  1. 1.0 1.1 1.2 1.3 Dickson DW (2009). "Neuropathology of non-Alzheimer degenerative disorders". Int J Clin Exp Pathol 3 (1): 1–23. PMC 2776269. PMID 19918325. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2776269/?tool=pubmed.
  2. Uversky, VN. (Oct 2008). "Alpha-synuclein misfolding and neurodegenerative diseases.". Curr Protein Pept Sci 9 (5): 507-40. PMID 18855701.
  3. MUN. 15 November 2010.
  4. 4.0 4.1 Seelaar H, Klijnsma KY, de Koning I, et al. (May 2010). "Frequency of ubiquitin and FUS-positive, TDP-43-negative frontotemporal lobar degeneration". J. Neurol. 257 (5): 747–53. doi:10.1007/s00415-009-5404-z. PMC 2864899. PMID 19946779. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864899/.
  5. Kumaran R, Kingsbury A, Coulter I, et al. (October 2007). "DJ-1 (PARK7) is associated with 3R and 4R tau neuronal and glial inclusions in neurodegenerative disorders". Neurobiol. Dis. 28 (1): 122–32. doi:10.1016/j.nbd.2007.07.012. PMID 17719794.
  6. Geser F, Brandmeir NJ, Kwong LK, et al. (May 2008). "Evidence of multisystem disorder in whole-brain map of pathological TDP-43 in amyotrophic lateral sclerosis". Arch. Neurol. 65 (5): 636–41. doi:10.1001/archneur.65.5.636. PMID 18474740.
  7. URL: http://dictionary.reference.com/browse/skein. Accessed on: 20 November 2010.
  8. Shiau, Carolyn; Toren, Andrew (2006). Toronto Notes 2006: Comprehensive Medical Reference (Review for MCCQE 1 and USMLE Step 2) (22nd edition (2006) ed.). Toronto Notes for Medical Students, Inc.. pp. PS19. ISBN 978-0968592861.
  9. Tuite, PJ.; Krawczewski, K. (Apr 2007). "Parkinsonism: a review-of-systems approach to diagnosis.". Semin Neurol 27 (2): 113-22. doi:10.1055/s-2007-971174. PMID 17390256.
  10. Ahmed, Z.; Asi, YT.; Sailer, A.; Lees, AJ.; Houlden, H.; Revesz, T.; Holton, JL. (Nov 2011). "Review: The neuropathology, pathophysiology and genetics of multiple system atrophy.". Neuropathol Appl Neurobiol. doi:10.1111/j.1365-2990.2011.01234.x. PMID 22074330.
  11. 11.0 11.1 Bertram, K.; Williams, DR. (Apr 2012). "Visual hallucinations in the differential diagnosis of parkinsonism.". J Neurol Neurosurg Psychiatry 83 (4): 448-52. doi:10.1136/jnnp-2011-300980. PMID 22228724.
  12. Mahmoud, F.; Tampi, RR. (Oct 2011). "Valproic Acid-Induced Parkinsonism in the Elderly: A Comprehensive Review of the Literature.". Am J Geriatr Pharmacother. doi:10.1016/j.amjopharm.2011.09.002. PMID 21993183.
  13. Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 674-5. ISBN 978-1416054542.
  14. Nieuwenhuis-Mark, RE.. "Diagnosing Alzheimer's dementia in Down syndrome: problems and possible solutions.". Res Dev Disabil 30 (5): 827-38. doi:10.1016/j.ridd.2009.01.010. PMID 19269132.
  15. Online 'Mendelian Inheritance in Man' (OMIM) 104311
  16. Online 'Mendelian Inheritance in Man' (OMIM) 600759
  17. Online 'Mendelian Inheritance in Man' (OMIM) 107741
  18. Braak H, Braak E, Bohl J (1993). "Staging of Alzheimer-related cortical destruction". Eur. Neurol. 33 (6): 403–8. PMID 8307060.
  19. Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1317. ISBN 978-1416031215.
  20. Braak, H.; Braak, E. (1991). "Neuropathological stageing of Alzheimer-related changes.". Acta Neuropathol 82 (4): 239-59. PMID 1759558.
  21. URL: http://www.pakmed.net/academic/age/alz/alz030.htm. Accessed on: 12 November 2010.
  22. URL: http://faculty.washington.edu/alexbert/MEDEX/Fall/NeuroPath_Obj.htm. Accessed on: 13 November 2010.
  23. Mirra, SS.; Heyman, A.; McKeel, D.; Sumi, SM.; Crain, BJ.; Brownlee, LM.; Vogel, FS.; Hughes, JP. et al. (Apr 1991). "The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Part II. Standardization of the neuropathologic assessment of Alzheimer's disease.". Neurology 41 (4): 479-86. PMID 2011243.
  24. URL: http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/npfrm.html. Accessed on: 5 December 2010.
  25. Montine, TJ.; Phelps, CH.; Beach, TG.; Bigio, EH.; Cairns, NJ.; Dickson, DW.; Duyckaerts, C.; Frosch, MP. et al. (Jan 2012). "National Institute on Aging-Alzheimer's Association guidelines for the neuropathologic assessment of Alzheimer's disease: a practical approach.". Acta Neuropathol 123 (1): 1-11. doi:10.1007/s00401-011-0910-3. PMID 22101365.
  26. Thal, DR.; Rüb, U.; Orantes, M.; Braak, H. (Jun 2002). "Phases of A beta-deposition in the human brain and its relevance for the development of AD.". Neurology 58 (12): 1791-800. PMID 12084879.
  27. Braak, H.; Braak, E. (1991). "Neuropathological stageing of Alzheimer-related changes.". Acta Neuropathol 82 (4): 239-59. PMID 1759558.
  28. Mirra, SS.; Heyman, A.; McKeel, D.; Sumi, SM.; Crain, BJ.; Brownlee, LM.; Vogel, FS.; Hughes, JP. et al. (Apr 1991). "The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Part II. Standardization of the neuropathologic assessment of Alzheimer's disease.". Neurology 41 (4): 479-86. PMID 2011243.
  29. 29.0 29.1 Watts JC, Balachandran A, Westaway D (March 2006). "The expanding universe of prion diseases". PLoS Pathog. 2 (3): e26. doi:10.1371/journal.ppat.0020026. PMC 1434791. PMID 16609731. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1434791/.
  30. 30.0 30.1 Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 672. ISBN 978-1416054542.
  31. Online 'Mendelian Inheritance in Man' (OMIM) 600072
  32. Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 671. ISBN 978-1416054542.
  33. Burton, Julian L.; Rutty, Guy N. (2010). The Hospital Autopsy A Manual of Fundamental Autopsy Practice (3rd ed.). Oxford University Press. pp. 83. ISBN 978-0340965146.
  34. URL: http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/N0I002-PQ01-M.htm. Accessed on: 19 October 2010.
  35. Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 419 Q4. ISBN 978-1416025887.
  36. URL: http://www.nysslha.org/i4a/pages/index.cfm?pageid=3519. Accessed on: 30 March 2011.
  37. Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 677. ISBN 978-1416054542.
  38. Online 'Mendelian Inheritance in Man' (OMIM) 609007
  39. Online 'Mendelian Inheritance in Man' (OMIM) 602544
  40. 40.0 40.1 Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1319. ISBN 978-1416031215.
  41. Wenning, GK.; Stefanova, N.; Jellinger, KA.; Poewe, W.; Schlossmacher, MG. (Sep 2008). "Multiple system atrophy: a primary oligodendrogliopathy.". Ann Neurol 64 (3): 239-46. doi:10.1002/ana.21465. PMID 18825660.
  42. MUN. 16 November 2010.
  43. Pimenta, PF.; da Silva, RP.; Sacks, DL.; da Silva, PP. (Apr 1989). "Cell surface nanoanatomy of Leishmania major as revealed by fracture-flip. A surface meshwork of 44 nm fusiform filaments identifies infective developmental stage promastigotes.". Eur J Cell Biol 48 (2): 180-90. PMID 2743996.
  44. 44.0 44.1 URL: http://emedicine.medscape.com/article/1151430-overview. Accessed on: 11 November 2010.
  45. Levy, R. (Jun 2011). "[Progressive supranuclear palsy: what's new?].". Geriatr Psychol Neuropsychiatr Vieil 9 (2): 191-201. doi:10.1684/pnv.2011.0271. PMID 21690028.
  46. Williams DR, Lees AJ (March 2009). "Progressive supranuclear palsy: clinicopathological concepts and diagnostic challenges". Lancet Neurol 8 (3): 270–9. doi:10.1016/S1474-4422(09)70042-0. PMID 19233037.
  47. URL: http://neuropathologyblog.blogspot.com/2008/03/grumose-degeneration-in-cerebellar.html. Accessed on: 4 December 2010.
  48. Yamanouchi H, Yokoo H, Yuhara Y, et al. (March 2002). "An autopsy case of ornithine transcarbamylase deficiency". Brain Dev. 24 (2): 91–4. PMID 11891099.
  49. 49.0 49.1 Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 676. ISBN 978-1416054542.
  50. URL: http://medical-dictionary.thefreedictionary.com/Walnut+Brain. Accessed on: 14 March 2012.
  51. Grossman, M. (Feb 2010). "Primary progressive aphasia: clinicopathological correlations.". Nat Rev Neurol 6 (2): 88-97. doi:10.1038/nrneurol.2009.216. PMID 20139998.
  52. Kumar P, Kalonia H, Kumar A (2010). "Huntington's disease: pathogenesis to animal models". Pharmacol Rep 62 (1): 1–14. PMID 20360611.
  53. Online 'Mendelian Inheritance in Man' (OMIM) 613004
  54. 54.0 54.1 Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 415 Q44. ISBN 978-1416025887.
  55. URL: http://moon.ouhsc.edu/kfung/jty1/NeuroTest/Q07-Ans.htm. Accessed on: 29 October 2010.
  56. URL: http://path.upmc.edu/cases/case117/gross.html. Accessed on: 3 January 2012.
  57. Online 'Mendelian Inheritance in Man' (OMIM) 105400
  58. 58.0 58.1 Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 679. ISBN 978-1416054542.
  59. URL: http://pathology.mc.duke.edu/neuropath/CNSlecture4/CNSlecture4.htm. Accessed on: 30 August 2011.
  60. URL: http://path.upmc.edu/cases/case207/dx.html. Accessed on: 11 January 2012.