CLINICAL RADIOLOGY
                                                                                                              
Cerebral Arteriovenous Malformations
                                                   

                                      A cerebral arteriovenous malformation (AVM) is an abnormal connection between the arteries and veins in the barin  .it is a vascular anomaly..

                     The most frequently observed problems related to an AVM are headaches and seizures while at least 15% of the population at detection have no symptoms at all. Other common symptoms are a pulsing noise in the head, progressive weakness and numbness and vision changes.

                        In serious cases, the blood vessels rupture and there is bleeding within the brain (intracranial hemorrhage). Nevertheless in more than half of patients with AVM, hemorrhage is the first symptom. Symptoms due to bleeding include loss of consciousness, sudden and severe headache, nausea, vomiting, incontinence, and blurred vision, amongst others. Impairments caused by local brain tissue damage on the bleed site are also possible, including seizure, one-sided weakness (hemi paresis), a loss of touch sensation on one side of the body and deficits in language processing (aphasia).Minor bleeding can occur with no noticeable   

 symptoms.

AVM in the BRAIN 

                                    AVMs in certain critical locations may stop the circulation of the cerebrospinal fluid, causing accumulation of the fluid within the skull and giving rise to a clinical condition called hydrocephalus. A stiff neck can occur as the result of increased pressure within the skull and irritation of the meninges.

                                       An AVM diagnosis is established by NEUROIMAGING studies after a complete neurological and physical examination. Three main techniques are used to visualize the brain and search for AVM:

1) Computed tomography (CT),

2) Magnetic resonance imaging (MRI),

3) Cerebral angiography.(DSA)

AVM in CT IMAGE 

CT findings:

      ·         Vascular tangles are serpiginous and hyperdense        without contrast from the blood pool effect.
      ·         AVMs may contain punctate or curvilinear    
              calcification.
      ·         AVMs will enhance

T2WI in MRI 

  

       MRI findings:

•   ·         Curvilinear flow voids
•   ·         MRA for mapping

AVM in DSA 

Angiogram (DSA):

  ·    Should demonstrate the three

       components of the enlarged 

       feeding       artery, core/nidus,

       and enlarged draining vein.

                ·      Smaller AVMs may simple 

                   demonstrate early venous 

                   filling during the arterial phase 

                   of enhancement

      

            Associated syndromes

  ü    Sturge Weber

  ü  Wyburn Mason

  ü  Klippel-Trenaunay-Weber

  ü  Osler Weber Rendu

 Complications

   ·         Hemorrhage

   ·         Steal phenomenon where blood 
        supply  is  preferentially delivered
        to AVM the cost of  normal brain 
        parenchyma and can lead to focal 
        neurological symptoms, seizure 
        and focal  atrophy.                                                                          

   ·        Aneurysms can form and become a source of   
         hemorrhage

Treatment

1. ·         Endovascular embolization
2. ·         Surgery
3. ·         Radiation therapy

                                                                                  

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