Reply

We appreciate the interest of our colleagues Toshihiro Ueda and William T.C. Yuh regarding our report of direct PTA for MCA occlusion. To our regret, our colleagues have misinterpreted our thesis and results. We reported that four (57%) of seven patients with embolic MCA trunk occlusion showed marked clinical improvement, although all patients had both early ischemic findings on the initial CT scan and LCA involvement, both of which have been reported to be predictive of hemorrhagic complications after thrombolytic therapy (1, 2). This good result indicates that early ischemic findings on the initial CT scan do not always suggest irreversibly damaged tissue.

In patients with these findings, urgent recanalization should be undertaken prior to the onset of irreversible brain damage. In patients with embolic MCA trunk occlusion, the embolus is often so large that it is resistant to thrombolysis. Therefore, mechanical crushing of the embolus by direct PTA is preferred to time-consuming thrombolytic therapy. Our rationale for choosing direct PTA for these patients is based on the high risk of hemorrhagic complication if thrombolytic therapy, using high doses of thrombolytic agents, is performed. We chose direct PTA in order to achieve rapid recanalization, not to avoid using thrombolytic agents. We agree with Ueda and Yuh that angioplasty is an effective option in reperfusion therapy for acute ischemic stroke that can achieve rapid recanalization (3).

In patients with embolic MCA trunk occlusion, conservative treatments often lead to extended space occupying cerebral edema or massive intracerebral hemorrhage owing to late spontaneous recanalization after complete damage of the vessel wall (4). Even if most of the ischemic tissue cannot escape cerebral infarction, therapeutic recanalization might be effective if recanalization could be performed without hemorrhagic complications, and the goal of rehabilitation could be improved. The purpose of recanalization therapy should be to improve clinical outcome, not solely an excellent recovery. We have never aimed to improve angiographic results; we do strive to improve long-term clinical outcome.

In our study, three (43%) of seven patients with embolic MCA occlusion had cerebral infarctions in spite of rapid recanalization, suggesting irreversible ischemic damage. In these three patients, however, neither space occupying cerebral edema nor massive intracerebral hemorrhage was found in the course of treatment because of rapid recanalization prior to the damage of the vessel wall. Rehabilitation of these three patients went well, and we believe that their clinical outcome was improved by the urgent recanalization therapy.

We have also demonstrated that direct PTA alone could achieve complete recanalization in five (71%) of seven patients with embolic MCA occlusion. Crushed fragments of the embolus migrate distally and often lyse spontaneously, resulting in complete recanalization without thrombolysis. In the other two patients, additional thrombolysis was required because of the distal embolization. Although distal embolization by crushed fragments is a noteworthy problem of direct PTA for cerebral embolism, thrombolysis of these fragments is likely to be easy with small amounts of thrombolytic agents. We agree with Ueda et al that a combination of angioplasty and thrombolysis is effective in some patients. In order to recanalize the occluded vessel as early as possible, direct PTA and subsequent thrombolysis of crushed thrombi should be effective.

Angioplasty is effective in patients with atherothrombolic stroke, particularly in failed thrombolysis or reocclusion cases; however, in patients with atherothrombotic MCA branch occlusion, sufficient arterial patency was not achieved with the minimum dilatation force of 2–3 atm because of the small diameter of the vessel.

In summary, angioplasty is an effective option in reperfusion therapy for acute MCA occlusion, particularly in patients with atherothrombotic stroke. Even in patients with embolic MCA occlusion, when early ischemic findings and LCA involvement are present, urgent recanalization by direct PTA should be performed, and additional thrombolysis may be required in some patients.