Meningitis Seminar By : Stephanie Ammari & Bayan Khawaldeh .

Meningitis Definition: It is an inflammation of meninges.

The meninges are the three membranes that cover the CNS (brain and spinal cord).

1. • Inflammation of the dura is rare & is known as pachmeningitis .

2. • Inflammation of the pia & arachnoid is

more common & known as : *leptomeningitis

Infection

If infection in brain tissue is called

1.Encephalaitis when it viral infection

2.Cerebritis or abscess when it bacterial,

fungal or parastiric. If it in meninges is called meningitis

Classification

Septic Meningitis "Bacterial

meningitis."

A Septic Meningitis”Mainly

visuses”

Viruses Bacteria”TB” Fungi Non Infectious

Septic Meningitis “Bacterial Meningitis” The CSF Contains mainly PMN due to infection of the meninges by pyogenic organisms.

The organisms causing bacterial meningitis vary with age and the predisposing factors of the host .The 3 most common meningeal pathogens accounting for more than 80% of cases are:

• Neisseria meningitidis (Meningococcus)

• Streptococcus pneumoniae

• Haemophilus influenzae

Mode of infection

𝐵𝑙𝑜𝑜𝑑𝑠𝑡𝑟𝑒𝑎𝑚 𝑓𝑟𝑜𝑚 𝑖𝑛𝑓𝑒𝑐𝑡𝑖𝑜𝑛 𝑜𝑓 𝑜𝑡𝑕𝑒𝑟 𝑠𝑖𝑡𝑒𝑠

𝐷𝑖𝑟𝑒𝑐𝑡 𝑓𝑟𝑜𝑚: 𝑇𝑟𝑎𝑢𝑚𝑎: 𝐿. 𝑃(𝑙𝑢𝑚𝑏𝑎𝑟 𝑝𝑢𝑛𝑐𝑡𝑢𝑟𝑒) . 𝑜𝑟 𝑝𝑒𝑛𝑒𝑡𝑟𝑎𝑡𝑖𝑛𝑔 𝑤𝑜𝑢𝑛𝑑

𝑆𝑒𝑝𝑡𝑖𝑐𝑓𝑜𝑐𝑢𝑠: 𝑠𝑖𝑛𝑢𝑠𝑖𝑡𝑖𝑠, 𝑜𝑡𝑖𝑡𝑖𝑠 𝑚𝑒𝑑𝑖𝑎 𝑜𝑟 𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦 𝑡𝑜 𝑒𝑛𝑐𝑒𝑝𝑕𝑎𝑙𝑖𝑡𝑖𝑠

Pathophysiology •Transmission, colonization and invasion of nasopharyngeal epithelium. •Survival in the blood stream by evading host immune response. •Meningeal invasion. Bacteremia may be rapidly followed by seeding of meningeal pathogens and secondary infection of the meninges. •CSF inflammatory response. •Cerebral edema and thrombosis. Cerebral edema may be caused by reduced CSF reabsorption by the arachnoid villi, or by vasogenic or cytotoxic means. Bacterial meningitis causes loss of Cerebrovascular anticoagulation

Clinical Picture The classic clinical triad of ‘meningism’ is: • headache • photophobia • neck stiffness

Signs

General Signs :

Pyrexia>>acute high fever

Pulse>>Tachycardia except in cases of ^^ICP??

Photophobia

Purpura or petechiae in meningococcal meningitis , with or without features of septic shock (Waterhouse-Friderichsen syndrome)

Clinical Picture Signs

Features of Increased ICP :

1)Headache ,due to ?

Onset : acute

Character :severe , increase by flexion of the neck & may be by lying down.

2)vomiting (projectile)

3)Papilloedema

Clinical Picture Signs

Features of meningeal irritation :

Pain : due to irritation of spinal sensory roots

Neck :rigidity

Body : Opisthotonus Position (high arched back)

Brudzinski sign

Kernig’s sign

Signs of neurological deficit :

Confusion or coma

Convulsion

Transient cranial nerve paralysis :??

Complication of meningitis : 1. Neurological:

•hydrocephalus , due to ??This is especially common in ??

•cerebral edema

•venous sinus thrombosis

•subdural empyema

• arteritis and endarteritis: TB can often inflame the origin of the cerebral vasculature as it rises from the base of the brain . In severe cases ,this can lead to occlusion of the artery causing a large vessel stroke. Meningitis can also inflame the smaller arteries within the meninges, causing further damage from ischemia.

•focal lesion as hemiplegia , aphasia with affection of the cortex (meningoencephalitis)

Complication of meningitis : 2.Cardiac: pericarditis -endocarditis.

3. Eye: conjunctivitis -keratitis iridocyclitis. & may be blindness

4.Ears :Deafness due to affection of the 8th cranial nerve. –

5.Others,Nephritis ,arthritis.

Viral Meningitis 1. Viruses are the most common cause of meningitis

2. usually resulting in a benign and self-limiting illness requiring no specific therapy.

3. It is much less serious than bacterial meningitis unless there is associated encephalitis.

4. the most common virus : enteroviruses.

5. Where specific immunisation is not employed, the mumps virus is a common cause.

Clinical Features of Viral Meningitis :

1. Viral meningitis occurs mainly in children or young adults .

2. acute onset of headache and irritability

3. the rapid development of meningism.

4. The headache is usually the most severe feature.

5. There may be a high pyrexia

6. focal neurological signs are rare.

Investigations & Diagnosis Viral Meningitis :

The diagnosis is made by lumbar puncture.

1.CSF is clear .

2. CSF usually contains an excess of lymphocytes.

3. glucose and protein levels are commonly normal, the latter may be raised.

***It is important to verify that the patient has not received antibiotics (for whatever cause) prior to the lumbar puncture, as CSF lymphocytosis can also be found in partially treated bacterial meningitis.

Investigations & Diagnosis Bacterial Meningitis :

* Lumbar puncture is mandatory unless there are contraindications .

*Lumber puncture will help differentiate the causative organism

*If the patient is drowsy and has focal neurological signs or seizures, is immunosuppressed, has undergone recent neurosurgery or has suffered a head injury, it is wise to obtain a CT to exclude a mass lesion (such as a cerebral abscess) before lumbar puncture because of the risk of coning.

* This should not delay treatment of presumed meningitis. -Gram film and culture may allow identification of the organism.

-Blood cultures may be positive.

-PCR techniques can be used on both blood and CSF to identify bacterial DNA.

-These methods are useful in detecting meningococcal infection and in typing the organism.

Contraindications of LP : 1. If there is a cranial space-occupying lesion causing raised intracranial pressure, LP presents a

theoretical risk of downward shift of intracerebral contents, a potentially fatal process known as

coning .

2. LP is contraindicated if there is any clinical suggestion of raised intracranial pressure

(papilloedema), depressed level of consciousness, or focal neurological signs suggesting a cerebral

lesion, until imaging (by CT or MRI) has excluded a space-occupying lesion or hydrocephalus.

**When there is a risk of local haemorrhage (thrombocytopenia, disseminated intravascular

coagulation or anticoagulant treatment), then caution should be exercised or specific measures

should be taken.

*** LP can be safely performed in patients on antiplatelet drugs or low-dose heparin, but may be

unsafe in patients who are fully anticoagulated due to the increased risk of epidural haematoma.

In bacterial meningitis :

1. the CSF is cloudy (turbid) due to the presence of many neutrophils (often > 1000 × 10^6

cells/L).

2. the protein content is significantly elevated

3. the glucose reduced.

Management Viral Meningitis :

-There is no specific treatment and the condition is usually benign and self-limiting.

-The patient should be treated symptomatically in a quiet environment.

-Recovery usually occurs within days, although a lymphocytic pleocytosis may persist in the CSF.

-Meningitis may also occur as a complication of a systemic viral infection such as mumps,

measles, infectious mononucleosis, herpes zoster and hepatitis. Whatever the virus, complete

recovery without specific therapy is the rule.

Management Bacterial Meningitis :

There is an untreated mortality rate of around 80%, so action must be swift.

In suspected bacterial meningitis the patient should be given parenteral benzylpenicillin

immediately (intravenous is preferable) and prompt hospital admission should be arranged.

The only contraindication is a history of penicillin anaphylaxis.

Recommended empirical therapies are outlined in Box 25.65 .

the preferred antibiotic when the organism is known after CSF examination is stipulated in

Box 25.66.

Adjunctive glucocorticoid therapy is useful in reducing hearing loss and neurological sequelae

in both children and adults in developed countries where the incidence of penicillin resistance

is low .

Management Bacterial Meningitis :

In meningococcal disease, mortality is doubled if the patient presents with features of sepsis

rather than meningitis.

Individuals likely to require intensive care facilities and expertise include those with cardiac,

respiratory or renal involvement, and those with CNS depression prejudicing the airway.

Early endotracheal intubation and mechanical ventilation protect the airway and may prevent

the development of the acute respiratory distress syndrome .

Adverse prognostic features include hypotensive shock, a rapidly developing rash, a

haemorrhagic diathesis, multisystem failure and age over 60 years.

Prevention of meningococcal infection :

Close contacts of patients with meningococcal infection (Box 25.67) should be given 2 days of

oral rifampicin. In adults, a single dose of ciprofloxacin is an alternative.

Tuberculous Meningitis * is now uncommon in developed countries except in immunocompromised individuals,

although it is still seen in those born in endemic areas and in developing countries.

* It is seen more frequently as a secondary infection in patients with the acquired

immunodeficiency syndrome (AIDS).

Pathophysiology :

Tuberculous meningitis most commonly occurs shortly after a primary infection in childhood

or as part of miliary tuberculosis .

The usual local source of infection is a caseous focus in the meninges or brain substance

adjacent to the CSF pathway. The brain is covered by a greenish, gelatinous exudate,

especially around the base, and numerous scattered tubercles are found on the meninges.

Tuberculous Meningitis : Clinical Features :

Onset is much slower than in other bacterial meningitis – over 2–8 weeks.

If untreated, tuberculous meningitis is fatal in a few weeks but complete recovery is usual if

treatment is started at stage I .

When treatment is initiated later, the rate of death or serious neurological deficit may be as

high as 30%.

The clinical features and staging criteria are listed in Box 25.68.

Tuberculous Meningitis Investigations :

Lumbar puncture should be performed if the diagnosis is suspected. The CSF is under increased pressure. It is usually clear but, when allowed to stand, a fine clot (‘spider web’) may form. The fluid contains up to 500 × 10^6 cells/L, predominantly lymphocytes, but can contain neutrophils. There is a rise in protein a marked fall in glucose. The tubercle bacillus may be detected in a smear of the centrifuged deposit from the CSF but a negative result

does not exclude the diagnosis. The CSF should be cultured but, as this result will not be known for up to 6 weeks, treatment must be started

without waiting for confirmation. Brain imaging may show hydrocephalus, brisk meningeal enhancement on enhanced CT or MRI, and/or an

intracranial tuberculoma.

Tuberculous Meningitis Management :

As soon as the diagnosis is made or strongly suspected, chemotherapy should be started using

one of the regimens that include pyrazinamide, described on page 592.

The use of glucocorticoids in addition to antituberculous therapy has been controversial.

Recent evidence suggests that it improves mortality, especially if given early, but not focal

neurological damage.

Surgical ventricular drainage may be needed if obstructive hydrocephalus develops. Skilled

nursing is essential during the acute phase of the illness, and adequate hydration and

nutrition must be maintained

Other forms of meningitis

Malignant meningitis usually presents with sequential cranial nerve palsies, initially painless, later painful, but can cause meningism. Spinal nerve root involvement also occurs.

Other forms of meningitis Fungal and bacterial causes of an aseptic meningitis picture include : Cryptococcal meningitis<<Most common fungal meningitis

in Europe, (Seen in AIDS, acute lymphocytic leukemia and lymphomas)

Endemic fungi Nocardia Mycobacterium tuberculosis Lyme meningitis can cause peripheral and cranial nerve

palsies, especially of the 7th cranial nerve (Bell's palsy) ;so think of Lyme disease or herpes simplex virus infection when a patient present with an isolated facial nerve palsy.

Differential Diagnosis of Meningitis B . Other infections of CNS

1.Poliomyelitis (in the early ‘meningeal phase’) – usually of short duration, meningeal signs not marked, hyperaesthesiae common, paralysis and more extensive. Lumbar puncture at once differentiates

2. Viral meningoencephalitis

– Distinct CSF findings – Glucose level normal, proteins less elevated (typically 0.5–2 g/L), and lymphocytosis

3. Post-infectious meningoencephalitis

Rare sequel of measles or influenza, or less frequently chickenpox, mumps or rubella, and certain vaccines

. 4. Focal infections

– such as brain abscess and subdural empyema may have similar clinical feature.Investigations to

determine a specific aetiology include CSF examination with specific stains for mycobacteria and fungi, cytology, antigen detection, serology, viral culture and blood culture. CT or MRI of brain

Differential Diagnosis of Meningitis C . Non Infectious Illness

though uncommon may cause CNS inflammation including

CSF Finding is useful

***Subarachnoid haemorrhage :

there are signs of meningeal irritation and sometime fever but the onset is more sudden and the CSF is bloody

malignancy

collagen vascular syndromes

exposure to toxins