P&S Journal: Winter 1995, Vol.15, No.1
By Robin Eisner,
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In the late 1960s, Dr. Sadek Hilal pioneered the technique of using catheters and dyes to detect and treat problems in the brain's vasculature. Through a shaft in the femoral artery of the leg, he placed a catheter containing a contrast dye and navigated through the torso's blood vessels and up into the brain's circulation. X-rays taken of the dye during the voyage guided him on his way.
Based on Dr. Hilal's work, the first neurointerventional radiological procedures done to stop bleeding in the brain-intracranial coil embolization and electrothrombosis-were performed at the Neurological Institute in the 1960s.
Since March of 1992, Dr. John Pile-Spellman, associate professor of radiology and of neurological surgery, has continued the tradition begun by Dr. Hilal, professor of radiology in neurological surgery. As director of one of the top four neurointervention al radiology centers in the country, Dr. Pile-Spellman coordinates a multidisciplinary team of physicians and nurses who perform from 300 to 350 neurointerventional procedures each year. Using the most advanced methods, the team treats a variety of comple x cerebral vascular diseases, including arteriovenous malformations, aneurysms, atherosclerotic diseases, tumors, and embolic or clotting diseases.
The largest proportion of cases-about 150 a year-in the team's practice is dedicated to rare arteriovenous malformations. AVM repair is exemplary of the teamwork, care, precision, and timing that neurointerventional techniques require for success. An AVM is an abnormal collection of blood vessels that can occur in the brain, spine, face, foot, and arms. Normally, arteries feed into a capillary bed and deposit the blood's nutrients and oxygen into tissues. Deoxygenated blood from the tissues then goes into the capillaries then flows through veins back to the lungs. AVMs lack the capillary bed. Blood from an artery flows directly into the veins at a high pressure, causing the veins to enlarge and, sometimes, to bleed.
Unfortunately, doctors often cannot detect an AVM unless a vein bursts or an AVM causes symptoms, such as a seizure. An AVM might be spotted during a diagnostic MRI of the brain done for other reasons. The AVM can be confirmed by an angiogram.
AVMs are treated by stopping the blood flow from the artery to the vein. Methods include surgery, radiation, embolization (a neurointerventional radiological method that uses glue or coils to block the blood flow), or a combination of procedures, dependin g on the nature and location of the AVM. When embolization is indicated, the procedure usually must be repeated two to three times, often followed by surgery to remove the occluded vasculature. Combining embolization and surgery, however, results in fewer complications and shorter hospital stays than with surgery alone. Because embolization stops bleeding, surgery after embolization is safer than surgery alone.
Patients with AVMs undergo a series of brain circulation studies and neuropsychological tests before they undergo neurointerventional procedures. The neuropsychological tests provide the physicians with a mental status baseline for assessment of effects o f the procedure. During the embolization, the patient is awake but made comfortable by an anesthesia team that monitors and, if necessary, adjusts blood flow during the procedure.
When the physicians find the AVM through angiography and access it, they inject a material that temporarily blocks blood flow in the brain. Physicians perform neuropsychological tests to see if blood flow stoppage in the area affects mental function. If m ental function is unchanged, Dr. Pile-Spellman uses a more permanent blocker, such as a glue or a coil.
The use of glue requires split-second timing. Dr. Pile-Spellman must get the adhesive to the AVM site before the glue hardens and passes into the vein. After glue is applied, an X-ray determines where the glue stuck to the vascular wall. Another series of neuropsychological tests measures mental function. The patient remains in the embolization suite for three to five hours.
Neurointerventional procedures generally are done on an investigational basis. Part of Dr. Pile-Spellman's work is devoted to clinical research that continues to search for better glues, contrast dyes, catheters, and coils, as well as treating patients in the first few hours after a stroke.