Focal Cerebellar Hyperperfusion After Bypass Surgery for Vertebrobasilar Ischemia: Effect of Cerebrovascular Reactivity as a Potential Predictor of Hyperperfusion

Intervention for symptomatic vertebrobasilar disease

Disease of the vertebral (VA) and basilar arteries (BA) can lead to stroke of the posterior circulation and may warrant management strategies which differ from the anterior circulation. The mechanism and location of the disease determine its natural history and therefore affect the relative risks and benefits of the possible treatment options. Vertebrobasilar (VB) atherosclerotic disease is a source of both hemodynamic and embolic posterior circulation stroke. Advances in medical therapy have decreased the rate of stroke after initial symptomatic presentation. Antiplatelet therapy, blood pressure control, and optimization of secondary risk factors can reduce recurrent stroke risk in both intracranial and extracranial VB disease. However, symptomatic intracranial disease is still associated with a high risk of subsequent stroke, particularly those with hemodynamic compromise who represent a higher risk population. Patients with hemodynamic impairment may benefit from judicious application of endovascular and microsurgical interventions to augment blood flow. Stenting, angioplasty alone, bypass surgery, and endarterectomy, represent endovascular and surgical tools available to address medically refractory VB disease. Apart from atherosclerotic disease, dissection is another etiology of VB stroke, most frequently affecting the extracranial VA. Treatment is predominantly antithrombotic therapy although surgical or endovascular intervention can be required in rare cases of persistent embolism or hemodynamic compromise. In contrast, extrinsic compromise of the VA represents a separate extracranial pathology and is best treated with mechanistically targeted surgeries or extracranial bypass.

Suspected Cerebral Hyperperfusion Syndrome after Stenting for Intracranial Vertebral Artery Stenosis Associated with Reduced Cerebral Blood Flow to the Posterior Cerebral Artery Territory

Objective

Although several studies have reported on cerebral hyperperfusion syndrome (CHS)/hyperperfusion phenomenon (HPP) involving the anterior circulation after carotid artery stenting (CAS), little is known about CHS/HPP involving the posterior circulation after percutaneous transluminal angioplasty (PTA) and stenting of the vertebral artery (VA).

Case Presentation

A 79-year-old man with known chronic occlusion of the left VA (V4 segment) was admitted to another hospital with right-sided hemiplegia, mild disturbance of consciousness, and dysphagia. A head MRI revealed multiple infarcts in posterior circulation areas, and severe stenosis of the right VA (V4 segment). Single photon emission computed tomography (SPECT) indicated reduced cerebral blood flow (CBF) in the posterior circulation, and DSA revealed 76% stenosis of the right V4 segment. On day 18, PTA/stenting was performed under general anesthesia for the severe stenosis of the right VA. However, head MRI and CT on postoperative day (POD)1 showed intracranial hemorrhage (ICH) occupying an area measuring 2 cm in diameter in the left posterior lobe and a small subdural hematoma (SDH). SPECT on POD1 indicated increased CBF in the posterior lobe, and we diagnosed CHS might have caused ICH. Although SPECT on POD4 showed residual hyperperfusion, SPECT on POD11 revealed reduced CBF in the posterior circulation area.

Conclusion

Our patient developed ICH after undergoing PTA/stenting for known severe symptomatic stenosis of the right VA. CHS/HPP in the posterior cerebral artery territory might be one of the etiologies, and reduced CBF prior to the procedure could be a risk factor for CHS/HPP developing after PTA/stenting.