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CNS Infection

Dr. Ali Omar Saadoon

Neurosurgeon

2013-2014

Brain abscess

• 8% of all intracranial space-occupying lesions

• %2 (most industrialized nations)

• Male: female ratio is 1.5-3:1

RISK FACTORS

• pulmonary abnormalities (infection, AV-fistulas ... ,

• congenital cyanotic heart disease

• bacterial endocarditis,

• penetrating head trauma

• chronic sinusitis or otitis media,

• immune compromise.

• dental procedures

The microorganism may reach the brain by different mechanisms:

1. Hematogenous spread from remote reservoir of infection( most common)

• Adults; lung abscess (the most common), bronchiectasis and empyema

• children; congenital cyanotic heart disease with R to L shunt • Immunosuppression (AIDS-toxoplasmosis)• pulmonary arteriovenous fistulas• bacterial endocarditis• dental abscess• GI infections: pelvic infections may gain access to the brain via

Batson's plexus

In patients with septic embolization, the risk of cerebral abscess formation is elevated in areas of previous infarction or ischemia

2. Contiguous site of infection (infected sinus,naso/oropharynx)

e.g. otitis media, mastoiditis,sinusitis,osteomyelitis ,dental abscess. Rare in infants because they lack aerated paranasal and mastoid air cells. This route has become less common due to improved treatment of sinus disease.

3. Direct inoculation from penetrating trauma or during neurosurgical procedures.(trauma, iatrogenic…post operative, congenital defect….dermal sinus

• Prior to 1980, the most common source of cerebral abscess was from contiguous

spread.

• Now, hematogenous dissemination is the most common vector.

• In some cases no source can be identified

The responsible microorganism

• Otitis media : anaerobic streptococci, Haemophilus and Gram-negative anaerobic

• Sinusitis: streptococcus milleri and staphylococcus

• Traumatic: staphylococcus • Hematogenous spread : various organism are

involved

Clinical features

• features of raised intracranial pressure

• Seizure

• meningeal irritation

• focal signs

• rapid progression

• Systemic features of infection are frequently absent

Investigation

• leucocytosis, raised ESR, and C-reactive protein ( may initially be normal)

• CT and MRI of brain: may show ring enhancing mass lesion (differ with the stage of the abscess)

• CXR and chest CT (if indicated) to look for pulmonary source.

• Cardiac echo .

Treatment

• identify the bacterial organism

• IV antibiotics(6-8 wks)

• surgery (drain or excision)

• treat the cause

• anticonvulsant therapy

Surgical treatment

• Needle aspiration : may be performed under local anesthesia if necessary, may be the only surgical treatment required but some time must be followed with excision, recommended with multiple or deep lesion, or with thin walled

• Surgical excision: abscess is removed as any well-encapsulated tumor; the length of time on antibiotics can be shortened.

complications

•With abscess rupture : ventriculitis, meningitis, venous sinus thrombosis

•CSF obstruction…hydrocephalus

•Transtentorial herniation

prognosis

• Mortality with appropriate therapy—10%

• Permanent deficit ---50%

subdural empyemas

• uncommon

• sinusitis or mastoiditis

• these patients are systemically unwell

• with rapidly progressive neurological signs

• a depressed level of consciousness and hemiparesis

• Epilepsy

Treatment

Like intracranial abscess,

complications include

refractory status epilepticus and cortical venous sinus thrombosis

Posttraumatic meningitis

• Occurs in 1-20% of patients with moderate to severe head injuries

• 75% of cases have basal skull fracture and 58% had CSF rhinorrhea.

TreatmentConservative treatment:

antibiotics are used according to the culture and sensitivity tests. There is high rate of infection with organisms indigenous to the nasal cavity

surgical treatment : repair of the dural tear .

Osteomyelitis of the skull

• The skull is very resistant to osteomyelitis,

• hematogenous infection is rare.

• usually due to infected air sinus, penetrating trauma or from scalp abscess

Treatment

• Antibiotics alone are rarely curative.• Treatment is usually surgical• debridement of infected skull

(craniectomy) .• and 6-12 weeks of antibiotics. • if no sings of infection a cranioplasty may

be performed after 6 months. Post-operative.

Spinal infection

Spine infection

1. vertebral osteomyelitis(spondylitis)

a. pyogenic

b. nonpyogenic e.g. tuberculous spondylitis

2. epidural abscess

3. discitis

a. spontaneous

b. post-operative

Spinal tuberculosis Pott's disease

more commone in third world countries. Is usually symptomatic for many months and affect more than one level.the most common levels involved are the lower thoracic and upper lumbar levels.

Has a predilection for vertebral body, sparing the posterior elements. Psoas abscess is common .

definitive diagnosis required a biopsy (may be done percutaneously) to identify the acid fast bacilli. Good results may be obtained with either medical treatment or surgery. Surgery is needed when definite cord compression is documented or for complication such as abscess or sinus formation.

Hydatid Cyst disease

• Caused by encysted larvae of the dog tapeworm Echinococcus granulosa

• CNS involvement occurs in only 3%• Primary cysts are usually solitary, secondary

cysts (e.g. from embolization from cardiac cysts that rupture or from iatrogenic rupture of cerebral cysts) are usually multiple.

• Presentation : ↑ ICP ,seizures , or focal deficit.• Treatment : surgical removal of intact cyst.

Brain Death

Neurologically Determined Death

Brain death

• Brain death defined as total and irreversible loss of function of the cerebral hemispheres and the brainstem.

• The patient may continue to have some spinal reflex activity, which dose not rule out the patient brain death.

• If ventilation and circulation are maintained artificially, the heart, kidneys, and liver may continue to function for some hours or days, but after brainstem death has occurred cardiac arrest will follow within 2 weeks.

Diagnosis of brain death

• The reversible causes of coma should be excluded (like hypothermia(tempreture should be above 32C),no electrolyte/acid-base/endocrine disturbance, pentobarbital coma, neuromuscular blocking agents, shock or intoxications).

• A committee should perform the testes.

The findings ….?

The findings• no motor response to deep central pain• fixed pupils : absent light reflex• absent corneal reflex• absent oculocephalic reflex(doll's eyes)• absent oculovestibular reflex (cold water calorics)• no motor responses within the cranial nerve

distribution can be elicited by adequate stimulation of any somatic area.

• no cough and gag reflex• no spontaneous respiration( disconnecting the patient

from the respirator to allow the Pco2 to rise to 60 mmHg)

• EEG dose not detect brainstem activity• brain arteriogram show total lack of cerebral blood flow

Thanks.Questions?