11.1.2021 1 Infections of the Nervous System Introduction Involvement of CNS during infection when a microorganism gain access to the CNS or by the immunopathologic mechanisms = neuroinfections by vascular, metabolic and toxic processes = toxoinfectious encephalopathies (non- inflammatory response of the CNS to infection) Classification of NS Infections (1) by localization of the disease process * central nervous system meningitis encephalitis myelitis * peripheral nervous system radiculitis neuritis * combined involvement meningoencephalitis encephalomyelitis polyradiculoneuritis Classification of NS Infections (2) by character of the inflammatory response * purulent * aseptic * specific by clinical course * acute * subacute * chronic Clinical Manifestations Meningitis: • sudden onset (in acute meningitis) • fever • headache • meningismus • altered mental status (in acute bacterial meningitis) Encephalitis: • altered mental status (24 h) • fever (3 days) • seizures • (new-onset) focal neurol. finding • CSF finding (pleocytosis) • (new) neuroimaging abnormality • EEG abnormality consistent with encephalitis presents with Meningism (1) The meningism includes symptoms and signs which appear as a result of meningeal irritation by * inflammation * hemorrhage * neoplasm * increased intracranial pressure, high temperature etc. Symptoms: * headache * vomiting * irritability, hyperesthesia, photophobia etc. Signs: * meningeal signs – inflammed sensory roots produce a reflex contraction of muscles, particularly paravertebral
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11.1.2021
1
Infections of the Nervous System
Introduction
Involvement of CNS during infection
when a microorganism gain access to the CNS
or by the immunopathologic mechanisms =
neuroinfections
by vascular, metabolic and toxic processes =
toxoinfectious encephalopathies (non-
inflammatory response of the CNS to infection)
Classification of NS Infections (1)
by localization of the disease process
* central nervous system
meningitis
encephalitis
myelitis
* peripheral nervous system
radiculitis
neuritis
* combined involvement
meningoencephalitis
encephalomyelitis
polyradiculoneuritis
Classification of NS Infections (2)
by character of the inflammatory response
* purulent
* aseptic
* specific
by clinical course
* acute
* subacute
* chronic
Clinical Manifestations
Meningitis:
• sudden onset (in acute meningitis)
• fever
• headache
• meningismus
• altered mental status (in acute bacterial meningitis)
Encephalitis:
• altered mental status (24 h)
• fever (3 days)
• seizures
• (new-onset) focal neurol. finding
• CSF finding (pleocytosis)
• (new) neuroimaging abnormality
• EEG abnormality consistent with encephalitis
presents with
Meningism (1)The meningism includes symptoms and signs which appear as a
result of meningeal irritation by
* inflammation
* hemorrhage
* neoplasm
* increased intracranial pressure, high temperature etc.
Symptoms:
* headache
* vomiting
* irritability, hyperesthesia, photophobia etc.
Signs:
* meningeal signs – inflammed sensory roots produce a reflex
contraction of muscles, particularly paravertebral
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Meningism (2)Lumbar Puncture (1)
LP with removal and analysis of CSF is an
essential procedure in the diagnosis of
meningitis and encephalitis
Indications for LP:
* To obtain CSF in a suspicion of meningitis
* Reduction of raised intracranial pressure
* Lumbar intrathecal instillation of drugs
Lumbar Puncture (2)
Contraindications for LP:
Mass lesion or very increased intracranial pressure (possible
danger of herniation - tentorial or cerebellar coning) Some
evidence for this circumstance are
rapidly developing depression of consciosness (coma)
focal neurologic signs
convulsions
papilledema.
Significant coagulopathy (possible danger of bleeding)
Infected lumbar area (possible danger of infection)
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Lumbar Puncture – contd.
Some complication have been associated with performance of the LP - ranging from mild problems to the most feared herniation:
mild discomfort with insertion of the spinal needle
frequent postpunction headache and neck stiffness (10-25% patients)
nerve root irritation
local bleeding (rarely does harm to the pt, although pts with coagulopathy or receiving anticoagulants)
infection with susequent meningitis (1/50 000 procedures)