Among patients with unruptured ICMAs, the mortality rate is 30%; in patients with ruptured ICMAs, the mortality rate approaches 80%.315,316 The reported occurrence of ICMAs is probably underestimated because some ICMAs remain asymptomatic and resolve with antimicrobial therapy. Streptococci and S aureus account for and ICMAs are seen with increased frequency among IDUs with IE.318 The dis- tal middle cerebral artery branches are most often involved, especially the bifurcations. Multiple ICMAs occur in 20% ; mortality rates are similar for multiple and single distal ICMAs. The mortality rate for patients with proximal ICMAs is >50%.321 The clinical presentation of patients with ICMAs is highly variable. Patients may develop severe headache, altered sen- sorium, or focal neurological deficits such as hemianopsia or cranial neuropathies. Neurological signs and symptoms are nonspecific and may suggest a mass lesion or an embolic Some ICMAs leak slowly before rupture and pro- duce mild meningeal irritation. Frequently, the spinal fluid in these patients is sterile, and it usually contains erythrocytes, leukocytes, and elevated protein. In other patients, there are no clinically recognized premonitory findings before sudden subarachnoid or intraventricular hemorrhage.315 Symptomatic cerebral emboli frequently but not invari- ably precede the finding of an ICMA.315 Therefore, imaging procedures to detect ICMAs are indicated in IE patients with localized or severe headaches; sterile meningitis, especially if erythrocytes or xanthochromia is present; or focal neurologi- cal signs. Several imaging modalities can be used to identify ICMAs; currently, there is no preferred initial imaging study that can be recommended.322 Techniques include cardiac (mul- tislice) CT angiography with 3D reconstruction, digital subtrac- tion angiography, and magnetic resonance angiography with 3D reconstruction. In cases when there is a high clinical suspi- cion of ICMAs and a negative initial screening with 1 of these modalities, then conventional angiography is reasonable to per- form. 