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Craniotomy: Arteriovenous Malformation (AVM)

Procedure description

A craniotomy for arteriovenous malformation (avm:  a blood vessel abnormality which consists of blood vessels which rapidly shunt blood from arteries to veins) is performed to remove a vascular malformation within the brain to  prevent it from bleeding.  The avm may have already bled, in which case a subarachnoid hemorrhage (bleeding around the brain) or intracerebral hemorrhage (bleeding within the brain) has occurred, or it may have been found incidentally on brain scans (CT or MRI).  

The patient will be taken to the operating room and put to sleep under general anesthesia.  The head will be partially shaved, to expose the area of operation.  The head is then placed in three fixation points (Mayfield head pins).  This provides the ability to keep the head perfectly still during the procedure.   A frameless navigational device to allow the surgeon to navigate, in "real time" within the brain, may be used.   The area where surgery is to be performed is then "prepped and draped" using an antibiotic solution.  Next, the surgeon will make an incision, and reflect the scalp over the area of intended brain exposure.  Then, an air powered drill is used to make a hole in the skull, and a "footplate attachment" on the drill, or another similar device, is used to cut open a flap of skull.  The dura mater (tough covering of the brain) is then opened.  An operating microscope is generally brought into the field, and the surgeon will open the  brain.  Generally this involves carefully dissecting between the lobes of the brain, or dissecting within the fissures of the brain.   Dissection will be performed down to the site of the avm, and the arteries leading into the avm will be dissected.  The goal of surgery is to divide the arteries wupplying the avm while leaving the veins draining it intact, until the end of the surgeon, to prevent the avm from "blowing up" with blood.  Another goal is to dissect on the boundary of the avm, removing all the abnormal blood vessels, but not injuring the normal brain.     Often the edges of the brain are gently supported using brain retractors.   Any visible bleeding points will be cauterized.  Often, hemostatic promoting material is gently laid over the surfaces of the brain, and closure is begun.  The surgeon will  close the dura, and approximate the skull using titanium plates to hold the bone together.  Next the scalp will be closed in layers, and a pressure monitor may be placed into the brain to allow the postoperative monitoring of pressure within the brain. 


Procedure Risks

Risks for craniotomy for aneurysm can be broken down into two categories, 1) those related to the operative site, and 2) those related to the risks of anesthesia. 

Risks related to the operative site: 

Surgical Exposure:  The patient is placed in a supine position (on their back), possibly turned to one side of the other with the support of rolls inder one side of the body.   Insicions in the scalp may range from small to quite large.  There is risk of non healing of the scalp or bone post operatively.  Although very uncommon, there can be injury to or tearing of the scalp from the pins on the Mayfield clamp.  The plates used to close the skull could erode through the skin after the wound has heeled.

Brain injury:  The surgery involves opening of the  surface of the brain, and going into the deep structures of the brain.  There is the possibility that there may be injury to the brain.  If so, this could result in weakness, seizures, stroke, paralysis, coma or death.  There may be residual fluid or blood, requiring additional surgery in the future. Rehemorrhage (rebleeding)  can also occur.  If there is vasospasm, postoperative stroke may occur.  Sometimes the bed of the avm may dilate postoperatively, resulting in hemorrhage.  Sometimes some of the avm may remain postoperatively, and this may potentially require additional open surgery, or stereotactic radiosurgery (focused radiation using either a Gamma Knife or a linear accelerator).    Postoperative cognitive  (thinking, mentality and personality) changes may occur.

General Risks:  These include such general difficulties, such as bleeding, infection, stroke, paralysis, coma and death.  Incisions on the low back generally heal well, but if could   be tender, or may heal in an unpleasant manner.  There is also the possibility that the surgery may not relieve the symptoms for which the procedure was performed.  The problem for which the surgery was performed may recur, requiring additional surgery in the future.  In addition, although every attempt is made to protect all areas of the body from pressure on nerves, skin and bones, injuries to these areas can occur, particularly with prolonged cases.

Risks of Anesthesia: Blood clots in the legs, heart attacks, reaction to the anesthetic, reaction to blood transfusion, if it given.


Post-operative care:

There is surprisingly relatively little pain associated with craniotomies.  Your surgeon will prescribe pain medications for any pain associated with the incision. 

  1. Immediately upon discharge, contact our office and set up an appointment for staple removal if one has not already been set up.
  2. Take it easy until seen by the physician.  This does not mean bed rest, but athletic activities during this period are definitely not recommended.  Please give your incision a chance to heal.  Avoid any type of activity which might risk a blow to the head.
  3. You may resume activity as your body permits, but avoid extremes.  For example, walking is fine, but avoid any strenuous running.  USE GOOD JUDGMENT  AND COMMON SENSE.  If you have a question, ask your doctor.
  4. No driving until cleared with your surgeon.  A driving test may be required, at the discretion of your surgeon.  Even though you may feel fine, your peripheral vision and reflexes may have been affected, and we want you to be safe on the road for yourself as well as for others.
  5. You may shower after you go home unless otherwise instructed.  Cover the incision with plastic wrap before the shower and remove it afterward.  Change dressing immediately.    You may shower without covering the incision one week after the staples are out.  Follow instructions concerning care of tapestrips, stitches or staples.  Your surgeon or his nurse clinician will explain the techniques used in the closure of your incision.
  6. Sexual activities are permitted.
  7. If you notice swelling, redness or opening of the incision, or if there is any clear fluid draining from it, please contact your surgeon immediately!  If you develop a fever, stiff neck or chills, contact the office immediately.  Take your temperature at 4:00 PM daily until the clips are removed.  Call if greater than 101 degrees Fahrenheit.
  8. If you have a seizure, notify our office or come to the emergency room.
  9. If you develop any new weakness, notify our office.
  10. If you have any paralysis or weakness, post-operative care will need to be tailored to this.  If a brace for an arm of a leg has been prescribed, use it as recommended by your surgeon.
  11. If you have any questions, call our office, and for after hours emergencies, call the medical society.
  12. Take your medications prescribed on discharge, as directed.
  13. Make sure to follow up with any other physicians involved in your care.  These may include your family physician, neurologist, radiation oncologist and oncologist.


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