Neuropathological examination

Anna Oevermann Division of Neurological Sciences (Neurocenter) Vetsuisse Faculty, University of Bern

Nuts and bolts of neuropathology

Removal of brain and spinal cord

Neuroanatomy

Macroscopic examination

Histology sampling

Basic reaction patterns at the histological level

Recognizing the major patterns

ESAVS 2014

http://www.vetsuisse-bern.ch/~vet-iml/lernmodule/htmls/npintro.html?neuropatho%7Cnpintro

Removal of the brain

Opening of the skull

Removal of the spinal cord

Neuroanatomy Use the ventricular system as your road map!

lateral ventricle

V. bulbi olfactorii

III.

IV.

aquaeduct

central canal olfactory lobe

cerebral cortex

thalamus

midbrain

cerebellum

spinal cord

pons, medulla

olfactory lobe

cerebral cortex

thalamus midbrain

pons, medulla, cerebellum

spinal cord

III. IV.

lateral ventricle

aquaeduct

central canal V. bulbi olfactorii

cerebral cortex caudate nucleus

rostral commissure

optic chiasm

capsula interna

claustrum putamen globus pallidus

corpus callosum

cerebral white matter

olfactory bulb olfactory tract

lateral ventricle

rhinal fissure

septal nuclei

transversal sections

Frontal lobe Basal nuclei

thalamus

hypothalamus

caudate nucleus

amygdala optic tract

corpus callosum

fimbria

capsula interna

hippocampus

hippocampus

cerebral peduncle

lateral ventricle

III.

III.

lateral ventricle fimbria

lateral ventricle

habenula

thalamus

III.

hippocampus

medial geniculate body aquaeduct

red nucleus

lateral ventricle

substantia nigra cerebral peduncle

rostral colliculus

pons

cerebral peduncle

aqueduct

caudal colliculus

midbrain

cerebellar cortex cerebellar white matter

cerebellar nuclei

fourth ventricle

pyramid

lateral recess

cranial nerve nuclei reticular formation

caudal cerebellar peduncle

trigeminal spinal tract

pyramid

Cranial nerve nuclei

brainstem, cerebellum

Formalin fixation

Macroscopical examination of brain and spinal cord

Fixed – Whole organ – Transverse sections

Examination of all structures and anatomical regions – Meninges – Vessels – Cranial nerves/Nerve roots – Hypophysis – Grey/white matter – Ventricular system – Choroid plexus

Characterisation of lesions

Alterations in Size/Shape/Symmetry

Space occupying (mass) /lytic (malacia) lesion

Color/Consistency

Demarcation

Distribution

– Focal/multifocal/diffuse

– Unilateral/bilateral - symmetrical/asymmetrical/random

– Structures affected

Grey/White matter, specific anatomical structures?

Foreign material: E.g. gun pellets, parasites

ESAVS 2014

EASVS 2007

Macroscopical examination

Transversal sections

Sampling for histology

Directed by – gross findings

– neurological examination

– diagnostic imaging

Representative sampling

Representative sampling

Stereotactic Biopsy

General strategy

Macroscopical examination Histological examination

Anatomical distribution

Disease category

Clinical history

Literature

VITAMIN D!

Lesion patterns!

Further examinations

Neuroanatomical localisation? Diagnostic imgaging?

eg special stains, immunohistochemistry, bacteriology, TEM, PCR

Histochemical stainings

Fundamental: H&E

Grey matter – H&E

White matter – H&E

Stainings for axons

Mod. Bielschowsky Holmes

Stainings for Nissl substance/neurons

Cresyl-Echt-Violet (+ Luxol fast blue: Klüver-Barrera)

Stainings for myelin

Marchi’s stain Luxol-Fast Blue/H&E

Stainings for infectious agents

Grocott methamine silver

PAS

Mucicarmin

Gram

Ziehl-Neelsen/Fite

Immunohistochemistry

In situ method for protein detection

Ramos-Vara, Vet Pathol 2005

ABC-method LSAB-method

Cellular markers

e.g.

Astrocytes: GFAP

Oligodendrocytes: Olig-2, CNP

Microglia: IBA-1, CD68

Neurons: Synaptophysin, NeuN, Neurofilaments, PGP9.5, …

GFAP

CNP Synaptophysin

Detection of infectious agents

Listeria monocytogenes Canine distemper

Artefacts

- White and grey matter vacuolation - Sloughing of ependymal cells

“Dark neurons”

Fading of granule cells

cc

lv

III

Pseudolesions

Subpial germinal cell layer Circumventricular organs Primitive precursor cells