Giant intracranial aneurysms may not be amenable to direct surgical clipping or endovascular coiling because of three critical factors: 1) lack of clear aneurysmal neck; 2) giant size; 3) involvement with critical perforating or branch vessels. Techniques of flow redirection, however, may offer an alternative treatment strategy for these difficult lesions. In this paper, we report on the use of this alternative strategy in the successful treatment of a left giant fusiform carotid terminus-M1 aneurysm in a 16 year-old boy suffering from Ehler-Danlos disease. This patient was admitted to our Institution because his aneurysm was continuing to be increasing in size, despite a previous ligation of his left cervical ICA which was performed at another institution 2 years earlier after the patient had experienced a hemorrhagic stroke. Upon admission, a neurological examination revealed a slight motor aphasia with mild right hemiparesis, remnant of the ancient stroke. Because of its size and the involvement with M1 perforating arteries, a direct aneurysm attack was deemed inadvisable. After an initial ECA-ICA high flow bypass which spontaneously thrombosed, we performed a repeated high flow bypass with the application of a single clip on M1, right distal to the fusiform dilatation. After an uneventful postoperative course, we were unable to observe any new neurological deficits after surgery. A CT scan on postoperative day 1 revealed that the aneurysm had undergone a spontaneous thrombosis which was completely obliterated at the time of a 6-month follow-up angiogram. At that time, the ECA-ICA bypass was found to be patent. In conclusion the alternative of flow alteration strategies can be successfully used in the treatment of aneurysms that cannot be safely trapped or occluded by traditional neurosurgical methods.