While preventive medical management of cerebrovascular disease, stroke and TIA, secondary to a symptomatic intracranial arterial stenosis (sICAS) is well known and includes dual antiplatelet therapy and high-dose statin, its initial recognition and management can be challenging when the patient presents with an acute stroke syndrome.  BP-dependent fluctuating deficit that resolves with supine positioning and fluid administration is a reliable clinical indicator of underlying sICAS. However, BP dependence is often missed in patients presenting with acute stroke syndrome due to time constraints and need for rapid decision making during the acute triage.  Penumbra without a core (PWC) on brain CT perfusion (CTP) provides a biomarker that can identify these patients, prevent unnecessary interventions, and allow individualization of treatment. We describe 3 cases that underscore the usefulness of this biomarker.

Using three case studies, this report illustrates the tenet that PWC is an imaging biomarker of sICAS. Patients with sICAS of the ICA or MCA, typically precipitated by hypoperfusion from autonomic/hemodynamic dysfunction or artery-to-artery embolism, present with lateralizing/localizing stroke symptoms that are often blood pressure dependent. CTP finding of PWC serves to alert the treating team of the presence of sICAS as the underlying pathophysiology. PWC can guide management of the patient. IV fluid resuscitation, supine/Trendelenburg positioning and correction of hemodynamic/autonomic dysfunction are the mainstay. For those meeting criteria, thrombectomy is an option best reserved for patients with complete occlusion with rapidly declining neurologic function as it often leads to reocclusion that may necessitate rescue intracranial stenting.

PWC is a unique finding on CTP that leads to timely diagnosis of sICAS and guides management for these challenging patients. Often these options comprise conservative measures to treat autonomic and hemodynamic dysfunction. Other options include stent-retriever thrombectomy and rescue angioplasty and stenting in select patients.