Neuro surgery

 
1

Fifth stage 

Neuro-Surgery

Lec-8 

د. عبدالرحمن 

2/5/2016 

Intracranial Infections in Neurosurgical Practice

A.  Bacterial Meningitis. 

B.  Brain Abscess. 

C.  Subdural Empyema. 

Progress of Meningitis 

  Meningeal inflammation. 
  Subpial encephalopathy. 
  Cortical venous thrombosis. 
  Cerebral oedema. 
  Death. 

Bacterial Meningitis 

  Complications: 

1.  Cerebral Oedema. 

2.  Seizures. 

3.  Hydrocephalus (communicating). 

4.  Subdural Effusion. 

5.  Subdural Empyema. 

6.  Brain Abscess. 

7.  Ventriculitis. 

Brain Abscess 

  Aetiology and Source of infection: 

1.  Haematogenous spread: from a known septic site or occult focus (e.g. from 

dental infection, respiratory tract infection or endocarditis), usually causes 

 
2

multiple brain abscesses. This route is commoner in patients having congenital 
heart disease with right to left shunt. 

2.  Direct spread: from an adjacent infected paranasal sinus, middle ear, or 

mastoid infection. 

3.  Post-traumatic: direct inoculation from trauma, or after surgery. 

Note: in 25% of patients, no cause can be identified. 

Sources of CNS infection 

  Haematogenous Abscess 
  Direct  spread 
  Post-traumatic abscess 

High Risk Patients for Brain Abscess 

  Cyanotic Heart disease. 
  Immunocompromised patients. 
  Diabetic patients. 
  Solid organ transplant. 
  Haematological malignancy. 
  Long term steroids. 

Brain Abscess Pathology 

Brain abscess will pass in four stages: 

  Early cerebritis: early 1-3 days with inflammatory cells. 
  Late cerebritis: days 4-9, with formation of necrotic core and increasing number of 

macrophages and fibroblasts. 

  Early capsule: days 10-13. 
  Late capsule (mature capsule): by day 14. 

The formation of a collagen capsule in a developing abscess is the single most important 
responsible that limits the spread of infection to the rest of the brain.  

  Brain Abscess Clinical Features: 

  Features of raised intracranial pressure. 
  Seizures. 

 
3

  Meningeal irritation. 
  Focal neurological signs. 
  Systemic features of infection like fever is present in half of the cases and is usually 

of low grade  

Brain Abscess Investigations: 

  Laboratory Investigations 
  Radiological Investigations 

A.  Laboratory Investigations: 

  White Blood Cells (WBC) count and Erythrocyte Sedimentation Rate (ESR) are usually 

elevated. 

  Measurement of C-reactive protein is useful in differentiating brain abscess from 

tumour as it is elevated in case of abscess. 

  Lumbar Puncture is contraindicated in case of brain abscess to avoid fatal brain 

herniation.  

B.   Radiological Investigations: 

  CT or MRI is the investigation of choice. 
  CT Brain is performed with and without contrast. 
  MRI is done with gadolinium enhancement. 
  They will show a single (or multiple) space occupying lesion that is well delineated 

with an enhancing wall, with variable surrounding oedema. 

  The differential diagnosis of a single brain abscess in CT or MRI is a solitary 

metastasis, primary brain tumour or cerebral infarction. 

  The differential diagnosis of multiple brain abscesses is from multiple metastasis and 

tuberculoma. 

Treatment of Brain Abscess: 

  Non-surgical treatment (medical treatment) 
  Surgical treatment 

A.  Non-surgical treatment (medical treatment): 

    This is indicated for an abscess that is less than 2.5 cm. It includes: 

 
4

  Antibiotics: Appropriate antibiotic selection is based on culture and sensitivity 

results, e.g.  penicillin-G, trimethoprim-sulphamethoxazole, and aminoglycoside. 

  Corticosteroids: help to reduce cerebral oedema. 
  Anticonvulsants Therapy. 

B.  Surgical treatment: 

  Aspiration versus excision. 
  Indications for Aspiration (Burr hole ± Stereotaxis): 

o  Multiple abscesses. 
o  A deeply seated abscess. 
o  A critical location (e.g. motor or speech area). 
o  Poor general condition of the patient. 

NOTE: Aspiration or drainage is followed by Intravenous Antibiotics for at least six weeks. 

  Indications for Excision (Craniotomy): 

o  Multilocular abscess. 
o  A superficial abscess. 
o  The presence of a foreign body. 
o  Fungal abscess. 
o  Cerebellar  Abscesses. 
o  Abscesses containing air. 
o  Abscesses  with CSF leak. 
o  Abscess which fail  to resolve. 

SUBDURAL EMPYEMA 

Source of infection: 

  Although uncommon, may develop following sinusitis or mastoiditis.  
  It carries a high mortality (5-10 %) 

Pus is collected: 

  Over cerebral convexity. 
  In the parafalcine space. 

Clinical picture: 

  Headache, fever and meningism. 

 
5

  Seizures are common. 
  Focal neurological deficits which may progress rapidly to: 
  Altered mental state and coma. 
  NOTE: The combination of fever and seizures with background of sinusitis is usually 

diagnostic of this lesion. 

Investigations: 

  CT scanning; Despite subdural empyema is a neurosurgical emergency, diagnosis is 

often delayed as the collection on CT is usually so slight and frequently missed. 

  MRI : useful when the diagnosis  is doubtful. 

Treatment: 

  Craniotomy and thorough drainage of the pus,  followed by: 
  Intravenous antibiotic. 
  Anticonvulsants. 

Complications: 

  Refractory status epilepticus. 
  Cortical vein/ venous sinus thrombosis.