Assessing adequacy of collateral circulation during balloon test occlusion of the internal carotid artery with 99mTc-HMPAO SPECT.

A balloon test occlusion of the internal carotid artery was performed in 11 patients with internal carotid artery aneurysms. Tolerance by patients was assessed by a combination of clinical examination; angiography; electroencephalography; 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) with relative quantification; and, in four patients, 99mTc-HMPAO SPECT with absolute quantification of cerebral blood flow. During test occlusion, angiography showed a patent circle of Willis in all patients. No patient developed new clinical findings or electroencephalographic changes. The SPECT studies of five patients in whom 99mTc-HMPAO was injected during test occlusion demonstrated changes from their baseline SPECT studies. The internal carotid artery was permanently occluded in two of these patients, neither of whom became symptomatic because of the occlusion. Three patients who demonstrated no changes between baseline and test occlusion SPECT studies underwent permanent occlusion of the internal carotid artery without incident, and postoperative SPECT images were unchanged from baseline. Our preliminary results suggest that patients who have no changes between baseline and test occlusion 99mTc-HMPAO SPECT studies should have adequate collateral circulation to sustain cerebral blood flow after occlusion of the internal carotid artery if no thromboembolic episodes occur. In contrast, a patient's tolerance of permanent occlusion cannot be consistently and reliably predicted if there are changes between baseline and test occlusion SPECT studies. In these patients, absolute quantitation of cerebral blood flow is important. Greater numbers of patients are required to confirm these initial results.

Treatment of dural carotid-cavernous fistulas via the superior ophthalmic vein.

Symptomatic patients with dural carotid-cavernous fistulas often require treatment. Traditional therapies, which often are not completely successful, include manual common carotid artery compression and embolization via transarterial routes. This report describes four symptomatic patients with spontaneous dural carotid-cavernous fistulas who were treated unsuccessfully with transarterial embolotherapy and subsequently treated successfully by having a detachable balloon introduced into the cavernous sinus via the superior ophthalmic vein, which was surgically exposed. The fistulas resolved without complications. Treatment of dural carotid-cavernous fistulas by means of the transvenous approach via the superior ophthalmic vein may be of benefit in selected patients.