Vertebrobasilar insufficiency: stable xenon computed tomography-cerebral blood flow study in posterior circulation revascularization

Advantages of petrosectomy for superficial temporal artery to superior cerebellar artery bypass based on three-dimensional distance measurements using cadaver heads

Superficial temporal artery (STA) to superior cerebellar artery (SCA) bypass is usually performed via the subtemporal approach (StA), anterior transpetrosal approach (ApA), or combined petrosal approach (CpA), but no study has yet reported a quantitative comparison of the operative field size provided by each approach, and the optimal approach is unclear. The objective of this study is to establish evidence for selecting the approach by using cadaver heads to measure the three-dimensional distances that represent the operative field size for STA-SCA bypass. Ten sides of 10 cadaver heads were used to perform the four approaches: StA, ApA with and without zygomatic arch osteotomy (ApA-ZO^- and ApA-ZO⁺), and CpA. For each approach, the major-axis length and the minor-axis length at the anastomosis site (La-A and Li-A), the major-axis length and the minor-axis length at the brain surface (La-B and Li-B), the depth from the brain surface to the anastomosis site (Dp), and the operating angles of the major axis and the minor axis (OAa and OAi) were measured. Shallower Dp and wider operating angle were obtained in the order CpA, ApA-ZO⁺, ApA-ZO^-, and StA. In all parameters, ApA-ZO^- extended the operative field more than StA. ApA-ZO⁺ extended La-B and OAa more than ApA-ZO^-, whereas it did not contribute to Dp and OAi. CpA significantly decreased Dp, and widened OAa and OAi more than ApA-ZO⁺. ApA and CpA greatly expanded the operative field compared with StA. These results provide criteria for selecting the optimal approach for STA-SCA bypass in light of an individual surgeon's anastomosis skill level.

Revascularizing the upper basilar circulation with saphenous vein grafts: operative technique and lessons learned

BACKGROUND

The purpose of this study was to report our operative technique and lessons learned using saphenous vein conduits to revascularize the rostral basilar circulation (ie, bypass to the posterior cerebral or superior cerebellar arteries). We also review the evolution of this technique for the treatment of vertebrobasilar insufficiency (VBI) and complex posterior fossa aneurysms.

METHODS

Data were collected retrospectively for 8 consecutive patients undergoing rostral basilar circulation saphenous vein bypass grafts at our institution between 1989 and 2004 for the treatment of VBI or in conjunction with Hunterian ligation of complex posterior circulation aneurysms. The indications for treatment, pre- and postoperative neurologic status, angiographic results, operative complications, and long-term clinical outcomes were analyzed for each patient.

RESULTS

With clinical and angiographic follow-up ranging from 3 months to 15 years, 7 of 8 bypasses remained patent, 3 of 3 aneurysms remained obliterated, and 4 of 5 patients with VBI experienced resolution of their preoperative symptoms. There were no surgery-related deaths, but 2 patients did experience major neurologic morbidity. The outcomes for the 217 total patients reported in the literature were as follows: 135 excellent (62%), 26 good (12%), 30 poor (14%), and 26 dead (12%).

CONCLUSIONS

Despite the risk of serious neurologic complications with this procedure, when one considers the natural history of untreated patients, saphenous vein revascularization of the rostral basilar circulation remains an acceptable option. Although surgical technique has varied, patient selection criteria, graft patency, and patient outcomes have been relatively constant over the past 25 years.

Usefulness of intravascular Doppler flow measurements in cerebral endovascular treatment. A comparison with trans cranial Doppler

SUMMARY

Measurement of cerebral blood flow in cerebral endovascular procedures is useful for the assessment of treatment effects. We used transcranial Doppler sonography (TCD) and Doppler guide wires (SmartWire((R)), Cardiometries Co.) in intravascular treatment. The cases were 6 brain arteriovenous malformations (AVM), 2 carotid cavernous fistulas (CCF), 2 facial angiomas, and 2 carotid stenoses. Intravascular cerebral blood flow measurements with the SmartWire were performed during the endovascular procedure. TCD was used pre- and post-endovascular treatment, and velocity, pulsatility index (PI) and resistance index (RI) were compared with the SmartWire. For both TCD and Smart Wire, blood velocity of the main artery decreased, and PI and RI were improved after embolisation of AVM. In angioplasty cases, post stenotic flow velocity, as measured by SmartWire, was improved, and the flow of MCA measured with TCD was also improved after treatment. The SmartWire is useful to assess cerebral blood flow changes during the neuroendovascular procedure. Combined with repeated follow up with TCD, Doppler flow measurements are useful to assess the effect of endovascular treatment.

Anastomosis of occipital artery to posterior cerebral artery with interposition of superficial temporal artery using occipital interhemispheric transtentorial approach: case report

BACKGROUND

Superficial temporal artery (STA)-superior cerebellar artery (SCA) anastomosis, and STA-posterior cerebral artery (PCA) anastomosis are considered suitable as surgical procedures for the treatment of patients with significant stenosis or occlusion in the rostral portion of the basilar artery and patients with significant stenosis or occlusion of the posterior cerebral artery, respectively. However, several authors have reported frequent and serious complications of these surgical procedures, including temporal lobe retraction edema and hematoma. In this study, we introduce a new surgical revascularization using an occipital interhemispheric transtentorial approach for the treatment of severe stenosis of the rostral portion of the basilar artery.

CASE REPORT

A 47-year-old man with hypertension noted the sudden onset of nuchal pain followed by vertigo, diplopia, drunken gait, and motor weakness on his right side. Angiography performed on the day of the onset disclosed severe stenosis of the basilar artery. The stenotic portion extended just distal to the anterior-inferior cerebellar artery (AICA) to just proximal to the SCA, and in addition, a pseudolumen was visualized just distal to the left AICA. The patient underwent right occipital artery (OA) to left PCA anastomosis with interposition of the STA using an occipital interhemispheric transtentorial approach. Marked improvement in dysarthria, diplopia, ataxia gait, and visual disturbance were noted and he was able to walk without aid 3 days after operation. A postoperative angiogram of the right OA obtained 25 days after operation demonstrated visualization of the left PCA via the anastomosed OA and STA graft.

CONCLUSIONS

OA-PCA anastomosis with interposition of STA graft using an occipital interhemispheric transtentorial approach can be substituted for STA-SCA anastomosis and STA-PCA anastomosis for treatment of stenosis/occlusion of the rostral portion of the basilar artery.

Percutaneous transluminal angioplasty for severe stenosis of the posterior cerebral artery: case report

The Stealth dilation catheter was used for the intravascular treatment of a patient who had hemodynamically significant stenosis of the posterior cerebral artery and had a history of recurrent transient ischemic attacks associated with right hemiparesis and ipsilateral hemianopia dating from March 1993. Cerebral perfusion studies prior to and after the intravenous administration of acetazolamide demonstrated regions of moderately low perfusion and low hemodynamic reserve in the territories of the left middle and posterior cerebral arteries. Cerebral angiograms demonstrated severe stenosis of the left posterior cerebral artery and occlusions of both middle cerebral arteries, which had leptomeningeal anastomoses with the posterior cerebral arteries. Percutaneous transluminal angioplasty (PTA) was performed using the Stealth catheter on the stenotic segment of the left posterior cerebral artery after left superficial temporal artery-middle cerebral artery anastomosis. The patient manifested marked improvement in her neurologic condition just after PTA, in association with marked increase in cerebral perfusion and hemodynamic reserve in the territories of the left middle and posterior cerebral arteries. We have presented evidence that PTA can be used to treat patients with stenosis of the first segment of the posterior cerebral artery and hemodynamic compromise in the territory that artery supplies.

Vertebrobasilar insufficiency: correlation of clinical and radiologic findings

Radiological and clinical findings of 20 cases with angiographically proven stenosis or occlusion of the vertebrobasilar system and with clinical signs and symptoms attributable to posterior circulation disorder were studied. A simplified classification of vertebrobasilar arterial disease was presented; type I refers to stenosis of the vertebrobasilar system or subclavian artery, type II refers to vertebrobasilar occlusion, and type III refers to vertebrobasilar branch disease. Type I lesions were further subdivided into types Ia and Ib; type Ia cases showed no infarction in the posterior territory, whereas type Ib cases showed one or more infarctions on computed tomography or magnetic resonance imaging. This angiographic classification is based on treatment options that can be adopted to specific types of lesion. In type I cases, lesions are usually amenable to surgical or angiographic intervention. In type II cases, short-term anticoagulation is the treatment of choice. In type III cases, treatment is primarily aimed at prevention of complication and further stroke.

Anastomosis of occipital artery to anterior inferior cerebellar artery with interposition of superficial temporal artery. Case report

A 56-year-old man with vertebrobasilar insufficiency and associated findings including quadriparesis, dysarthria, cerebellar ataxia, nystagmus, and somnolence underwent left occipital artery (OA) to anterior inferior cerebellar artery (AICA) anastomosis with interposition of a superficial temporal artery (STA) graft. This procedure was chosen because cerebral angiograms demonstrated occlusion of the right vertebral artery (V3) and severe stenosis of the V4 segment of the left vertebral artery, with perfusion of the territory of the left posterior inferior cerebellar artery via the ipsilateral AICA, and because dissection of the OA is a relatively difficult and time-consuming procedure. Dissection of the STA, on the other hand, is much easier. Preoperative measurements of local cerebral blood flow in the vertebrobasilar circulation before and after intravenous administration of acetazolamide (500 mg) were obtained, and demonstrated low flow and hemodynamic compromise in the posterior circulation. The patient's hemodynamic and neurological status improved following surgery. In this report, we present a new and simplified method of OA-AICA anastomosis with interposition of STA graft.