Angiographic findings and clinical significance of the anterior and posterior spinal arteries in therapeutic parent artery occlusion for vertebral artery aneurysms

Abstract

Three of 16 patients with vertebral artery (VA) aneurysms treated by parent artery occlusion suffered ischemic complications. The cause of the ischemic complications was brain stem or upper cervical spinal cord infarction due to occlusion of the anterior spinal artery (ASA), posterior spinal artery (PSA) and perforating arteries arising from the VA. Angiographic detection of ASA and PSA was studied in 71 consecutive patients (142 VAs) with various diseases who underwent digital subtraction angiography. The ASA and PSA originated from the bilateral VAs in 14% and 9%, unilateral VA in 73% and 35%, and were not detected in 13% and 56%, respectively. These results indicate that the rate of angiographic detection of the ASA originating from the bilateral VAs is considerably lower than that of previously reported anatomical studies. Special attention must be paid to the ASA, PSA and perforating arteries on preoperative vertebral angiography to prevent ischemic complications associated with therapeutic parent artery occlusion for VA aneurysms.

Figure 1

(Case 11) A 61-year-old man with a “distal to posterior inferior cerebellar artery (PICA)” type fusiform aneurysm presenting with mass effect. A) Right vertebral angiogram showing a fusiform aneurysm located distal to the PICA. B) Left vertebral angiogram after embolisation of both the parent artery and the aneurysm showing the anterior spinal artery (ASA) originating from the vertebral artery (VA) stump. C) Seven hours after embolisation, left hemiparesis and right lower limb paresis appeared. Left vertebral angiogram demonstrating thrombosis of the VA stump and the ASA. D, E) Magnetic resonance (MR) image showing infarction in the lateral part of medulla oblongata and the anterior part of CI level of spinal cord.

Figure 2

(Case 8) A 42-year-old man with a “proximal to PICA” type dissecting aneurysm presenting with brain stem infarction. A) Right vertebral angiogram showing a “proximal to PICA” type dissecting aneurysm. Note the small arteries (arrows), supposed to be the posterior spinal artery (PSA) or perforating arteries, arising from the proximal VA. Arrowhead indicates the ipsilateral PICA. B) Left vertebral angiogram after parent artery occlusion showing preservation of the PICA and disappearance of the small arteries. Immediately after the procedure, right hemihypesthesia and hemiataxia occurred. C, D) MR images on admission showing a small infarction in the right posterolateral part of the medulla oblongata, e, f) MR images performed one day after the embolisation showing enlargement of the lesion of the medulla and a new infarction at the CI level of the spinal cord (white arrows).

Figure 2

(Case 8) A 42-year-old man with a “proximal to PICA” type dissecting aneurysm presenting with brain stem infarction. A) Right vertebral angiogram showing a “proximal to PICA” type dissecting aneurysm. Note the small arteries (arrows), supposed to be the posterior spinal artery (PSA) or perforating arteries, arising from the proximal VA. Arrowhead indicates the ipsilateral PICA. B) Left vertebral angiogram after parent artery occlusion showing preservation of the PICA and disappearance of the small arteries. Immediately after the procedure, right hemihypesthesia and hemiataxia occurred. C, D) MR images on admission showing a small infarction in the right posterolateral part of the medulla oblongata, e, f) MR images performed one day after the embolisation showing enlargement of the lesion of the medulla and a new infarction at the CI level of the spinal cord (white arrows).

Figure 3

(Case 10) A 55-year-old man with a “proximal to PICA” type dissecting aneurysm presenting with subarachnoid haemorrhage. A) Right vertebral angiogram showing a “proximal to PICA” type dissecting aneurysm. Note that neither the perforating arteries nor PSA are shown in the proximal VA. B) Left vertebral angiogram after embolisation showing the right PICA supplied via the contralateral VA. After the procedure, right hemi-numbness, hypesthesia, truncal ataxia and right hypoglossal nerve paresis emerged. C) MR image on the next day showing an infarction in the posterolateral part of the junction of the medulla oblongata and spinal cord.

Figure 4

Schematic drawings of the occluded segment (area colored black) and the VA stump supposed to be thrombosed (area of oblique lines) in four types of VA aneurysms. A) “distal to PICA” type. B) “proximal to PICA” type. C) “no PICA” type. D) “PICA involved” type.