We read with interest the article by Soeda et al (1) in January 2003 issue of the AJNR. The authors presented their experience with thromboembolic events detected by use of diffusion-weighted imaging that were associated with Guglielmi detachable coil (GDC) embolization. They concluded that thromboembolic events are relatively common in association with the balloon-assisted technique. We would like to take this opportunity to emphasize the following point.
In 1994, Moret et al (2) described the balloon-assisted technique for treatment of wide-necked or broad-based aneurysms with maximal sac diameter to neck size ratio of close to 1. The invention of the technique provided a new option in the treatment of wide-necked aneurysms and became the preferred method for their treatment. Soeda et al (1) found that diffusion-weighted abnormality was detected in 50% of small aneurysms with small necks, in 73% of small aneurysms with wide necks, 100% in large aneurysms, and 73% (22/30) in the procedure with balloon-assisted technique. They concluded that the occurrence of thromboembolic events depended on procedural complexity such as larger aneurysms (P < .01) and the use of balloon-assisted technique (P <. 05). Although we agree that larger aneurysms or those with poor morphology can cause more frequent thromboembolic events, we do not agree with authors’ second conclusion that the use of the balloon-assisted technique more frequently causes thromboembolic events. We assume that authors should have used the balloon-assisted remodeling technique for small aneurysms with wide necks and in large aneurysms despite small aneurysms with small necks. (This information was not given in the study.) As a result, the authors cannot conclude that the use of the balloon-assisted technique more frequently causes thromboembolic events. Small aneurysms with wide necks (73%) and larger, wide-necked aneurysms (100%) did not cause thromboembolic events more frequently than the use of the balloon-assisted technique (73%). Their conclusion might mistakenly discourage the use of the balloon-assisted technique, despite our experience (almost 50%) and Soeda et al’s study (1) (49%) that the balloon-assisted technique should be used for treatment in a half of aneurysm cases accepted in the interventional neuroradiology suite.
In summary, because balloon-assisted techniques are used for treatment of wide-necked large and small aneurysms alike and the frequency of thromboembolic events in associated with balloon-assisted technique (73%) was not greater than that of thromboembolic events in small aneurysm with wide neck (73%) and larger aneurysm with wide neck (100%), the authors cannot conclude that the infarcts related to the use of GDC embolization are more common sequelae with use of balloon-assisted technique
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We thank Drs. Sait Albayram and Dogan Selcuk for their interest and comments regarding our article (1). Although they agreed that thromboembolic events occur more frequently in the Guglielmi detachable coil (GDC) embolizations of larger and wide-necked aneurysms, they doubt direct causal relationship between the use of balloon-assisted techniques and higher frequency of such events, assuming that we should have used this technique for larger and small aneurysms with wide necks. This is not the case. In fact, we used the balloon-assisted technique in 47% of small aneurysms with small neck, 50% of small aneurysms with wide neck, and 29% of large aneurysms. Of the small-necked aneurysms treated with balloon-assisted technique, the hyperintense lesions were detected in 70% of patients. Therefore, we concluded that the use of balloon-assisted techniques has a causal relationship to higher frequency of thromboembolic events, not the epiphenomenon of more frequent use of this technique for more complex aneurysms as they assumed.
Although the proportion of aneurysms treated with the balloon-assisted technique was not clearly reported, at most centers this technique was used after conventional treatment had failed. We used this technique for a high percentage of small-necked aneurysms. The reason for this high percentage in cases where we anticipated difficulties is because the microcatheter could not be introduced into the aneurysmal sac by conventional GDC techniques or because we feared that the coils would protrude into the parent artery. In such cases, we introduced the balloon into the parent vessel beforehand, obviating catheter exchanges.
In our recent retrospective study (2), most thromboembolic events related to the GDC embolization may be caused by placement of the guiding catheters as well as manipulation of microcatheters. This study supported previous results and suggested the risk of significant emboli will likely increase with increasing procedural complexity such as large aneurysm or use of balloon-assisted technique.
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