Pathology

Grossly, the substantia nigra and locus ceruleus are discolored. The basal ganglia, brainstem tegmentum, and cerebral cortex are variably atrophic.

The histology is characterized by neuronal degeneration in distinct anatomic regions and the presence of neuronal and glial cytoplasmic inclusions (Table 5.14).

Neuronal Degeneration

The principal sites of neuronal degeneration are (a) the substantia nigra and the pallidostriatal structures, (b) the mesencephalic and pontine tegmentum, and (c) the cerebral cortex, chiefly the frontal and limbic areas. The thalamus, subthalamic nucleus, pontine nuclei, medullary tegmentum, inferior olives, and cerebellum are variably affected. The fiber tracts of the degenerated neurons are severely or completely demyelinated. Astrocytic fibrosis in the affected regions is moderate to severe (Figs. 5.25 through 5.27).

Neuronal and Glial Cytoplasmic Inclusions Neuronal and glial cytoplasmic inclusions are argyro-philic and immunoreact for tau protein. The neuronal inclusions are fibrillary tangles, mostly in globose form. Tau-positive neurons and threads and curly fibers of dystrophic neurites are dispersed throughout the neuro-pil (Fig. 5.28). Glial inclusions occur in both astrocytes and oligodendrocytes. The astrocytic inclusions are thorn-shaped or tufted astrocytes and astrocytic plaques. The oligodendrocytic inclusions are coiled bodies of filaments around the nuclei (Fig. 5.29).

TABLE 5.

13(B).

Neurodegenerative Diseases with Parkinsonism: Differentiating Pathologic Features

Cytopla

smic Inclusions

Neuronal

Molecular

Staining

Diseases

Degeneration

Neurons

Astrocytes

Oligodendrocytes

Component

Characteristic

PSP

Midbrain and

Neurofibrillary

Tufted

Coiled bodies

Tau protein

Argyrophilic

brainstem, limbic

tangles

Thorn-shaped

cortex

CBD

Frontoparietal

Corticobasal

Plaques

Coiled bodies

Tau protein

Argyrophilic

cortex, basal

bodies

Tufted

ganglia, substantia

Thorn-shaped

nigra

FTDP-17

Frontotemporal

Round/oval

Plaques

Coiled bodies

Tau protein

Argyrophilic

cortex, substantia

tangle-like

Tufted

nigra, basal ganglia

Thorn-shaped

MSA

Cerebellum, striatum

Oval, round

Oval, round

a-synuclein

Argyrophilic

Substantia nigra

triangular

Autonomic neurons

(Papp-Lantos

inclusions)

Progressive Supranuclear Palsy

TABLE 5.14.

Progressive Supranuclear Palsy

Molecular Pathology Tau-positive inclusions Neurons Glial cells

Astrocytes Oligodendrocytes

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