Cns response to injury

1. Cells of the CNS & their Response to Injury &
hydrocephalus

2.  Two cell types
◦ Neuron
 Conducts nerve impulses
 Cannot be replaced if destroyed
◦ Glia cells
 Support, nourish, and protect the neurons
 Include astrocytes, oligodendrocytes, ependymal cells
and microglia

4.  Neurons
◦ Acute (RED neuron, karyolysis)
◦ Subacute, chronic, cell loss, gliosis
◦ Axonal reaction
◦ Inclusions (lipid, prot., carb., viruses)
 Glia, “gliosis”
◦ Swelling
◦ Fibers
◦ Inclusions

5.  Acute neuronal injury (red neuron)
◦ Refers to a spectrum of changes that accompany acute CNS
hypoxia/ischemia or other acute insults that ultimately lead
to death of the cell

6.  Acute neuronal injury (red neuron)
◦ The morphologic features consist of shrinkage of the cell
body, pyknosis of the nucleus, disappearance of nucleolus,
and loss of Nissl substance, with intense eosinophilia of the
cytoplasm

7. ACUTE NEURONAL INJURY
“RED” NEURONS

8.  Subacute and chronic neuronal injury
(“degeneration”)
◦ Refers to situations leading to neuronal death occurring as a
result of a progressive disease process of some duration, as
is seen in certain slowly evolving neurologic diseases (such
as amyotrophic lateral sclerosis)

9.  Subacute and chronic neuronal injury
(“degeneration”)
◦ The characteristic histologic featrure is cell loss, often
selectively involving functionally related systems of
neurons, and reactive gliosis

11.  Axonal reaction
◦ Refers to the reaction within the cell body that attends
regeneration of the axon

12.  Neuronal damage may be associated with a wide
range of subcellular alterations in the neuronal
organelles and cytoskeleton
◦ Neuronal inclusions may occur as a manifestation of:
◦ aging, when there are intracytoplasmic accumulations of
complex lipids (lipofuscin), proteins, or carbohydrates .
◦ Viral infection can lead to abnormal intranuclear inclusions,
as seen in herpetic infection (Cowdry body), cytoplasmic
inclusions, as seen in rabies (Negri body), or both nucleus
and cytoplasm (cytomegalovirus)

13.  Cowdry Body intranuclear inclusion in a
neuron in herpes simplex encephalitis.

15.  Some degenerative diseases of the CNS are
associated with neuronal intracytoplasmic inclusions,
such as neurofibrillary tangles of Alzheimer disease
and Lewy bodies of Parkinson disease;
 Other diseases cause abnormal vacuolization of the
perikaryon and neuronal cell processes in the
neuropil (Creutzfeldt-Jakob disease)

17. Lewy body:Parkinson’s
disease

18.  Gliosis
◦ The most important histopathologic indicator of CNS injury
◦ Astrocytes participate in this process by undergoing both
hypertrophy and hyperplasia .

19.  Cellular swelling
◦ Is the swelling of the astrocyte cytoplasm, occurs regularly
in acute insults, as in hypoxia, hypoglycemia, and toxic
injuries

20.  Rosenthal fibers
◦ Are thick, elongated, brightly eosinophillic structures that
occur within astrocytic processes
◦ Rosenthal fibers are typically found in regions of long-
standing gliosis

22.  Corpora amylacea
◦ Or polyglucosan bodies, are round, faintly basophilic,
periodic acid-Schiff (PAS)-positive, concentrically lamellated
structures ranging between 5 and 50 μm in diameter and
located wherever there are astrocytic end processes,
especially in the subpial and perivascular zones
◦ They represent a degenerative change in the astrocyte, and
they occur in increasing numbers with advancing age .

23.  Corpora amylacea are
basophilic structures
often found in the
subpial space of aged
patients.

25. 25

26.  Constitutes accessory circulatory system
 produced mainly by choroids plexus of the
lateral ventricles(~500 ml/day) – foramina of
Munro – third ventricle – aqueduct of Sylvius
– 4th. Ventricle – foramina of Luscka and
Magendi – subarachnoid space - absorbed by
arachnoid villi – dural venous sinuses .

27. Definition:
 Is the enlargement of the ventricles with
increase in the volume of CSF
Usually associated with increased CSF
pressure
It is required shunting procedures to relieve
pressure

28. A, Hydrocephalus. Dilated lateral ventricles seen in a
coronal section through the midthalamus.

29.  CLASSIFICATION:
*Communicating (entire)(increased production of
CSF or decreased absorption by
arachnoidal granulations)
*Non-communicating (part)(obstructive),
congenital or acquired
 a) congenital malformation
 b) neoplasms
 c) inflammation
 d) hemorrhage
◦
◦ *Hydrocephalus ex vacuo

30.  HYDROCEPHALUS...(cont.)
CAUSES:
*CSF overproduction, choroid plexus
papilloma .
*Failure of absorption by arachnoidal
granulations e.g. Post-meningitic
leptomeningeal fibrosis, dura mater sinus
thrombosis, abnormal arachnoidal
granulations.

31.  HYDROCEPHALUS...(cont.)
CAUSES...
*Congenital stenosis or atresic aqueduct
 Aqueduct of Sylvius is most common location
of obstruction (congenital malformation)
 *Obstruction of 3rd ventricle/aqueduct by cysts
or neoplasia, gliosis/chronic inflamm. of
aqueduct,
 obstruction of 4th ventricle,
organized subarachnoidal hemorrhage .

32. Hydrocephalus ex vacuo:
 Refers to dilatation of the ventricular
system with a compensatory increase in CSF
volume secondary to a loss of brain
parenchyma (atrophy) e.g. Alzheimer´s
disease .

34. Clinical Features:
 Infants: sutures not fused;
Enlargement of the head ( circumference)
with NO symptoms of raised intracranial
pressure.
 Adults: Symptoms of raised intracranial
pressures. NO change in head circumference.
 * treatment  ventricular shunting

36. Hydrocephalus ex vacuo is secondary to
 a) Over production of CSF
 b) Obstruction
 c) Impaired absorbtion
 d) Brain atrophy