Oral infection including etiology, clinical features, histological

1. Introduction
 There are 2 types of tissues in the nervous system:
 Neuroectodermal tissues
 which include neurons (nerve cells) and neuroglia, and
together form the predominant constituent of the CNS.
 Mesodermal tissues
 are microglia, dura mater, the leptomeninges (pia-arachnoid),
blood vessels and their accompanying mesenchymal cells.
 The predominant tissues comprising the nervous system
and their general response to injury are briefly considered
are neurons, neuroglia, microglia, dura matter and pia
arachnoid.

2. Introduction cont…
 Brain
Makes up 2 % (1.4 kg) of
body weight Consumes
20% of the energy.
 Three major areas: the
cerebrum, the brain stem,
and the cerebellum.
 Brain and spinal cord
covered by meninges (dura,
arachnoid, and pia mater)
which provide protection,
support, and nourishment
to the brain and spinal cord.

3. Developmental Anomalies
 Spinal Cord Defects
 Spina bifida: malformations of the vertebral column involving
incomplete embryologic closure of one or more of the vertebral
arches (rachischisis), most frequently in the lumbosacral region.
 Meningocele: The herniated sac in meningocele consists of dura
and arachnoid.
 meningomyelocele - spinal cord or its roots herniate through the
defect and are attached to the posterior wall of the sac.
 Hydrocephalus- increased volume of CSF within the skull,
accompanied by dilatation of the ventricles.
 internal hydrocephalus: it involving ventricular dilatation.
 external hydrocephalus: A localized collection of CSF in the
subarachnoid space

4. Infections
 A large number of pathogens comprising various kinds of
bacteria, fungi, viruses, rickettsiae and parasites can cause
infections of the nervous system.
 The route of causes are Via blood stream, direct implantation,
local extension and along nerve.
1. Meningitis
 is inflammatory involvement of the meninges.
 may involve the dura called pachymeningitis, or the
leptomeninges (pia-arachnoid) termed leptomeningitis.
 An extradural abscess may form by suppuration between the
bone and dura.
 Further spread of infection may penetrate the dura and form
a subdural abscess
 pachymeningitis are localised or generalised leptomeningitis
and cerebral abscess.

5. Meningitis cont---
A. Acute Pyogenic Meningitis
 Acute pyogenic or acute purulent meningitis is acute infection of the pia-
arachnoid and of the CSF enclosed in the subarachnoid space
 Etiopathogenesis
 Escherichia coli, Haemophilus influenzae, Neisseria meningitidis, Streptococcus
pneumoniae
 Route of causes- The blood stream, from an adjacent focus of infection and by
iatrogenic infection such as during operation or lumbar puncture.
 Morphological features
 Grossly, pus accumulates in the subarachnoid space so that normally clear CSF
becomes turbid or frankly purulent.
 Clinical Manifestations
• fever, severe headache, vomiting, drowsiness, stupor, coma, and occasionally,
convulsions

6. Meningitis cont---
B. Acute Lymphocytic (Viral, Aseptic) Meningitis
 etiologic agents are numerous viruses such as enteroviruses,
mumps, ECHO viruses, coxsackie virus, Epstein-Barr virus,
herpes simplex virus-2, arthropode-borne viruses and HIV
 Morphologic Features
 Grossly, some cases show swelling of the brain while others
show no distinctive change.
 The clinical manifestations of viral meningitis are much the
same as in bacterial meningitis.
 The CSF findings in viral meningitis: CSF pressure increased
(above 250 mm water)

7. Meningitis cont---
C. Chronic (tuberculosis and Cryptococcus) Meningitis
 Tuberculosis meningitis: hematogenous spread of infection
from tuberculosis elsewhere in the body
 Cryptococcus meningitis: occurs immunocompromised
persons via hematogenous from a pulmonary lesion.
 Morphologic features
 The subarachnoid space contains thick exudate, particularly
abundant in the sulci and the base of the brain
 CSF Finding: Raised CSF pressure (above 300 mm water).
 Clinical Manifestations: headache, confusion, malaise and
vomiting.
 The clinical course in cryptococcal meningitis may fulminant
and fatal in a few weeks, or be indolent for months to years.

8. Encephalitis
 It is parenchymal infection of brain.
 caused by bacterial, viral, fungal and protozoal infections.
1. Bacterial Encephalitis- bacterial cerebritis that progresses to
form brain abscess
 tuberculosis and neurosyphilis are the two primary bacterial
involvements of the brain parenchyma
 Morphologically it appears as a localised area of
inflammatory necrosis and oedema surrounded by fibrous
capsule.
 Microscopically, the changes consist of liquefactive necrosis in
the centre of the abscess containing pus.

9. Encephalitis cot…
 Brain abscess
Caused by
 By direct implantation of organisms e.g. following compound
fractures of the skull.
 By local extension of infection e.g. chronic supportive otitis
media, mastoiditis and sinusitis.
 hematogenous spread e.g. from primary infection in the
heart such as acute bacterial endocarditis, and from lungs
such as in bronchiectasis
 Clinical Manifestations are fever, headache, vomiting, seizures
and focal neurological deficits depending upon the location of
the abscess

10. Encephalitis cot…
 Tuberculoma: is an intracranial mass occurring secondary to
dissemination of tuberculosis elsewhere in the body.
 Grossly, it has a central area of caseation necrosis surrounded
by fibrous capsule.
 Microscopically, there is typical tuberculous granulomatous
reaction around the central caseation necrosis.

11. Cerebrovascular Diseases
 Intracranial hemorrhage
 Hemorrhage into the brain may be traumatic, non-traumatic,
or spontaneous
 Intracerebral Hemorrhage
 Spontaneous intracerebral hemorrhage occurs mostly in
patients of hypertension
 Morphologic features.
 Grossly and microscopically, the hemorrhage consists of dark
mass of clotted blood replacing brain parenchyma.
 Clinical Manifestation
 Clinically the onset is usually sudden with headache and loss
of consciousness

12. Cerebrovascular Diseases cont---
 Subarachnoid Hemorrhage
 Hemorrhage into the subarachnoid space is most commonly
caused by rupture of an aneurysm, and rarely, rupture of a
vascular malformation.
 In more than 85% cases of subarachnoid hemorrhage,
 the cause is massive and sudden bleeding from a berry
aneurysm on or near the circle of Willis.
 Morphologic features.
 Rupture of a berry aneurysm frequently spreads hemorrhage
throughout the subarachnoid space with rise in intracranial
pressure and characteristic blood-stained CSF.

13. Trauma to The CNS
1. Epidural Haematoma
• is accumulation of blood between the dura and the skull following
fracture of the skull, most commonly from rupture of middle
meningeal artery.
2. Subdural Haematoma
 is accumulation of blood between the dura and subarachnoid.

14. Causes of increased ICP
 Intracranial bleeding
 Increased CSF production and reduced absorption.
 Tumors inside crania
 Injury Traumatic Brain Injuries
 Hydrocephalus
 Brain Tumor
 Severe Hypertension
 Venous Sinus Thrombosis
 Restricting Jugular Venous flow

15. Pathophysiology
 Increased ICP from any cause decreases cerebral perfusion
 Stimulates further swelling (edema)
 Shifts brain tissue through openings in the rigid dura, resulting
in herniation, a dire, frequently fatal event.
 Decreased Cerebral Blood Flow (resulting in ischemia and cell
death)

16. Pathophysiology cont…
 The body’s response to a decreased CPP is to raise
 blood pressure and dilate blood vessels in the brain
– This increases cerebral blood volume
– This increases ICP
– This decreases Cerebral Perfusion Pressure (CPP)
– This causes normal body response
– This increases cerebral blood volume
– This increases ICP
– This decreases CPP
 systemic pressure rises to maintain cerebral blood flow.

17. Manifestation
 Changes first in LOC
 Abnormal respiratory and vasomotor responses.
 Restlessness
 Stuporous
 Comatose and exhibits abnormal motor responses
 Pupils dilated and fixed and respirations impaired, death is usually
inevitable.

18. Complications
• Brain stem herniation
• The patient becomes volume-overloaded
• urine output diminishes, and serum sodium concentration
becomes dilute.
• Seizure
• Stroke
• Neurological damage and death.

19. CNS Tumors
 Tumours of the CNS may originate in the brain or spinal cord
primary tumours, or may spread to the brain from another
primary site of cancer( metastatic tumours).
 Secondary tumor is most common
 Both benign and malignant CNS tumours are capable of
producing neurologic impairment depending upon their site.

20. Classification of Intracranial Tumours:
 Tumours of neuroglia (gliomas)
 Astrocytoma, oligodendroglioma, ependymoma and choroid
plexus papilloma
 Tumours of neurons
 Neuroblastoma, ganglioneuroblastoma and ganglioneuroma
 Tumours of neurons and neuroglia
 Ganglioglioma
 Medulloblastoma, neuroblastoma, pnet(primitive
neuroectodermal tumor)
 Tumours of meninges
 Meningioma and meningeal sarcoma

21. Classification of Intracranial Tumours cont…
 Nerve sheath tumours
 Schwannoma (neurilemmoma), neurofibroma and malignant
nerve sheath tumour
 Other primary intraparenchymal tumours
 Haemangioblastoma, primary CNS lymphoma and germ cell
tumours.
 Miscellaneous tumours
 Malignant melanoma, Craniopharyngioma, Pineal cell
tumours and Pituitary tumours
 Tumour-like lesions
 (epidermal cyst, dermoid cyst, colloid cyst)

22. TUMOURS OF THE CNS

23. General Considerations of Tumors
 Most tumors are intracranial; tumors of the spinal cord are
much less frequent.
 In adults, the majority of intracranial tumors are supratentorial.
 In children, the majority of intracranial tumors are infratentorial
i.e lower back part of brain.
 CNS tumors are the second most common form of malignancy in
children (only leukemia is more frequent).
 Primary malignant CNS tumors rarely metastasize.
 Benign intracranial tumors can result in devastating clinical
consequences due to compression phenomena.
 Metastatic tumors to the brain are found more frequently than
primary intracranial neoplasms.

24. General Considerations Of Tumors cont…
 the most common primary intracranial tumors in adults are
glioblastoma multiforme, meningioma, and acoustic neuroma.
 The most common primary intracranial tumors in children are
cerebellar astrocytoma and medulloblastoma.
 Gliomas
 The term glioma is used for all tumors arising from neuroglia,
or more precisely, from neuroectodermal epithelial tissue.
 Gliomas are the most common of the primary CNS tumors and
collectively account for 40% of all intracranial tumours.
 Gliomas are disseminated to other parts of the CNS by CSF
but they rarely ever metastasize beyond the CNS.

25. Astrocytomas
 Astrocytomas are the most common primary brain tumors.
 They can be divided based on their infiltration into the
surrounding brain parenchyma.
 Astrocytomas that do not infiltrate the brain include pilocytic
astrocytomas, pleomorphic xanthroastrocytomas,and
subependymal giant cell astrocytomas.
 Diffuse astrocytomascan be further subdivided based on grade.
 low-grade fibrillary astrocytomasare WHO grade II.
 anaplastic astrocytomasare WHO grade III.
 glioblastoma multiforme (gBM)is WHO grade IV.

27. CNS Tumors cont…
 Oligodendroglioma
 This neoplasm presents as a slow-growing tumor in the middle-
age group and typically arises in the cerebral hemispheres.
 Morphologic characteristics
 Closely packed cells with large round nuclei surrounded by a clear
halo of cytoplasm (“fried egg” appearance)
 Tumor divided into groups of cells by delicate capillary strands
 Foci of calcification
 Microscopically
 the tumor is characterized by uniform cells with round to oval
nuclei surrounded by a clear halo of cytoplasm and well-defined
cell membranes.

28. CNS Tumors Cont…
 Ependymoma
 This neoplasm most frequently occurs in the fourth ventricle.
 Peak incidence is in childhood and adolescence.
 Histologic characteristics
 Include tubules or rosettes with cells encircling vessels or
pointing toward a central lumen.
 characteristically demonstrate blepharoplasts, rod-shaped
structures near the nucleus representing basal bodies of cilia.
 Results may papillary growths that obstruct flow of CSF and lead
to hydrocephalus.
 Microscopically
 the tumour is composed of uniform epithelial (ependymal) cells
forming rosettes, canals and perivascular pseudorosettes.

29. CNS Tumors Cont…
 Meningioma
 This is the second most common primary intracranial neoplasm.
 Most cases are benign
 slow growing (WHO grade I) and certain subtypes show more
aggressive behavior;
 the clear cell and chordoid variants are WHO grade II and
 the papillary and rhabdoid variants are WHO grade III.
 This neoplasm most often occurs after 30 years of age. It occurs
more frequently in women than in men.
 The neoplasm originates in arachnoidal cells of the meninges; the
tumor is external to the brain and can often be successfully
removed surgically.

30. CNS Tumor cont…
 This neoplasm occurs most frequently in the convexities of the
cerebral hemispheres and the parasagittal region; other
common locations falxcerebri, sphenoid ridge, olfactory area,
and suprasellar region.
 Morphologic features:
 meningioma is well-circumscribed, solid, spherical or
hemispherical mass of varying size (1-10 cm in diameter).
 Histologic characteristics
a whorled pattern of concentrically arranged spindle cells and
laminated calcified psammoma bodies

31. CNS Tumors cont…
 Medulloblastoma
 This is one of the most common neoplasms of childhood.
 It is a highly malignant tumor of the cerebellum.
 Morphologic features:
 the tumour typically protrudes into the fourth ventricle as a soft,
greywhite mass or invades the surface of the cerebellum.
 Microscopically
is composed of small, poorly-differentiated cells with ill-defined
cytoplasmic and a tendency to be arranged around blood vessels
and occasionally forms pseudorosettes.

32. CNS Tumors cont…
 Neuroblastoma
 This neoplasm is closely related to neuroblastoma of the adrenal
medulla or sympathetic ganglia.
 This is much less common than peripheral neuroblastoma.
 Characteristics
 a greater degree of amplification correlates with worse prognosis.
 Hemangioblastoma
 This neoplasm occurs most frequently in the cerebellum.
 It may be associated with similar lesions in the retina and other
organs.
 It sometimes produces erythropoietin, leading to secondary
polycythemia.

33. CNS Tumors cont…
 Schwannoma (neurilemmoma)
 This benign, slowly growing encapsulated tumor arises from
Schwann cells.
 When intracranial, it is most frequently localized to the eighth
cranial nerve (acoustic neuroma,acoustic schwannoma);
 Acoustic neuroma is the third most common primary intracranial
neoplasm.
 It also originates frequently in posterior nerve roots and
peripheral nerves.
 Histologically
 Antoni A: interlacing bundles of elongated cells with palisading
nuclei
 Antoni B: looser, less cellular pattern than Antoni A

34. CNS Tumors cont…
 Metastatic tumors
 These tumors are more common than any of the primary
intracranial neoplasms.
 They originate most frequently from primary sites in lung,
breast, skin, kidney, gastrointestinal tract, and thyroid.