Cavernous Malformations


Diagnosis and Surgical Management of Cavernous Malformations

 

Cerebral vascular malformations occur in 0.5 percent to 4 percent of the general population. Of the four classically described types of vascular malformations- arteriovenous malformations, cavernous malformations (CMs), capillary teleangiectasias and venous malformations-CMs account for 8 percent to 15 percent. CMs occur sporadic and familial (autosomal dominant).

 

Epidemiology and Clinical Presentation

Magnetic resonance imaging (MRI) greatly enhances our understanding of the natural history of these lesions. The spontaneous form occurs generally as a single lesion, whereas the familial form is characterized by multiple lesions. More than 80 percent of all lesions are supratentorial, 15 percent are located in the brainstem and posterior fossa with the remaining lesions in the spinal cord.

 

Alois Zauner, MD
Neurosurgeon
Santa Barbara Cottage Hospital

 

Most patients become symptomatic between their second and fifth decades. approximately 20 percent of lesions are found during a workup for headaches. seizures are the most common manifestations of supratentorial CMs. Abnormal venous flow and venous hypertension may lead to hemorrhagic angiogenic proliferation. Deposition of hemosiderin and iron is the likely cause for new onset of seizure activities.

 

The lesions are lobulated and well circumscribed, and are composed of dilated capillary vessels with simple endothelial lining and without brain tissue between the vascular channels. Ultrastructural analysis suggests abnormalities of the interendothelial tight junctions and subendothelial layer of the blood-brain barrier.

 

CMs may coexist in combination with other vascular malformations or as part of a transitional form of vascular malformations.

 

The natural history of CMs is generally related to their clinical presentation, MRi findings, and location. Incidental lesions have a low risk of symptomatic hemorrhage (<2 percent per year). The risk for recurrent symptomatic hemorrhage is higher in the brain stem and basal ganglia and may lead to severe neurological deficits and disability.

 

Management Of CMs

A logical approach to the management of CMs requires that neurosurgeons understand the epidemiology, natural history, and proper imaging of these lesions. Microsurgical resection with the aid of neuronavigation and other advanced neuro-surgical tools provides good results for the majority of surgical cases. The effectiveness of radiotherapy and radiosurgery in CMs is not well understood and is considered ineffective for most lesions. However, a recent report suggests stereotactic radiosurgery may reduce the risk of re-hemorrhage in selected deep seated CMs in patients who are not good surgical candidates.

   

 

A suboccipital approach via the fourth ventricle This was the preferred route to the pontomedullary vascular lesion, as demonstrated in the drawing. the course of the cranial nerves VI and VII and the posterior inferior cerebellar artery (PICA) are illustrated.

 


 

Case Study

A 42-year-old male presented with declining general health and worsening neurological symptoms over a period of four years. The patient had at least three re-hemorrhages, the last two of which occurred within two months. On admission, patient was unable to walk or swallow and had to be treated for pneumonia prior to surgery.

 

Surgical Considerations And Approach

Considering the pontomedullary location of the lesion and close approximation to the floor of the fourth ventricle, a telovelar approach to the lesion was chosen. Intraoperative frameless navigation and brainstem monitoring was used to optimize the surgical corridor and to guaranty the safety of the patient.

 

Postoperatively, the patient's symptoms improved very quickly and he was transferred to our inpatient rehabilitation center within one week. Four months after surgery, patient was able to return to his previous life with only minor neurological deficits.


 

BELOW:  Pre- and postoperative MRI studies Pontomedullary lesion with various stages of hemosiderin and blood products as seen on MRI. Note the cervical syrinx due to the mass effect of the cavernoma. As expected, the syrinx disappeared after surgery.

 

 
 
 

 


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