ENDOVASCULAR TREATMENT OF CEREBRAL ANEURYSMS

Rupture of an intracranial aneurysm can result in serious permanent neurological deficit or death. It is estimated that approximately 2% of the general population harbors a cerebral aneurysm and 25,000 aneurysms rupture in North America each year. Of patients with hemorrhage, in spite of aggressive treatment 45-50% of patients die immediately or within two weeks. If untreated, up to half of the survivors will suffer significant neurologic injury or death from subsequent hemorrhage or vasospasm. Conventional treatment of an intracranial aneurysm has been by open craniotomy and clipping of the neck with various types of clips. Certain aneurysms bear unfavorable configuration, size of neck, or location, and therefore proper clipping may not be possible. With the introduction of transarterial intracranial navigation of catheters in the 1970's, a new era of possible endovascular occlusion of these difficult aneurysms began.

Endovascular detachable coil treatment

A new method of endovascular obliteration of intracranial aneurysms using Guglieimi Detachable colis (GDC) was initially reported in 1991. This system is used, among others, at our institution and thus far appears to be a safe technique.

The aneurysm is reached using standard techniques for cerebral angiography. A small catheter is threaded from the femoral artery up into the major cranial vessel involved. A smaller catheter is then advanced into the aneurysm. The soft platinum GDC coils are then threaded through the catheter into the aneurysm. As the coil is advanced into the aneurysm it conforms to the shape of the aneurysm. By applying a low voltage direct current to a stainless steel wire at the base of the coil, the platinum coil is detached.

The platinum coils are extremely soft and have a preformed shape. Once extruded from the catheter tip, the coil forms a loop to prevent unnecessary stress to the aneurysm wall. The coils are available in a variety of lengths from 4- 40 cm. Each coil has its own preformed radius. One great benefit of these coils is the ability to withdraw the coil prior to final placement. This allows repositioning or possible exchange of the coil for a different size if it does not conform perfectly to the aneurysm. By packing the aneurysm with a number of coils, the aneurysm can be completely excluded from the circulation and thrombosed.

Results

Since April 1991, Dr. In Sup Choi has treated 44 intracranial aneurysms in 43 patients (12 patients at the MGH Aneurysm/AVM Center since September 1992 with the other patients treated at NYU Medical Center). Fourteen of the patients treated presented with subarachnoid hemorrhage, 13 with mass effect, 4 with seizure, 2 with thrombo-embolism, 2 with carotid cavernous fistulas, and 9 aneurysms were found incidentally during workup for other causes. More than half of the aneurysms were giant size (larger than 25 mm in diameter).

Complete obliteration was achieved in 21 aneurysms on initial postembolization angiograms (Figure 1). In 19 cases, a small portion of the aneurysm neck was opacified. Partial occlusion was accomplished in 4 cases due to various reasons, either purposely or due to technical difficulty. Rupture of an aneurysm did not occur in this series. Followup angiograms (up to one year) revealed no change in 32, increased aneurysm lumen in 8, decreased lumen in 3, and a new lumen in one patient with a partially thrombosed cavernous aneurysm who was treated with coumadin for deep vein thrombosis. Two of the patients with increased aneurysm lumens were retreated with GDC coils. There were 3 transient neurological complications, 2 due to thrombosis of the parent artery and 1 due to a peripheral emboli. Three permanent neurologic complications had occurred from thrombosis of parent vessels in spite of immediate thrombolysis: 1 monoparesis, 1 hemiparesis, and 1 fourth nerve palsy.

Possibilities for future treatment involve combining GDC coils with surgical clipping of aneurysms. One problem with the GDC coil is that partial packing may leave a small aneurysmal remnant which over time may re-expand into a new aneurysm. Whether or not this phenomenon will occur remains to be seen, however the coils are soft enough that it is feasible to consider a treatment with the coils initially, followed by surgical clipping of the lesion to avoid any remnant whatsoever.

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