Ruptured mycotic cerebral aneurysm development from pseudoocclusion due to septic embolism
A 14-year-old girl with no major past medical history was sent to the emergency department for evaluation after her primary care doctor found a new heart murmur on physical examination in the setting of a 2-week history of fevers, myalgias, fatigue, and shortness of breath. She was admitted to the hospital for treatment of subacute endocarditis and was found to have blood cultures positive for nontypeable Hemophilus influenzae. Mitral valve vegetations were confirmed on transesophageal echocardiography. The patient's history was remarkable for a recent orthodontic appliance adjustment 1 month prior to admission.\nNeurosurgical involvement began after the patient was found to have a right middle cerebral artery (MCA) territory infarct on computed tomographic (CT) imaging with symptoms starting 1 day earlier consisting of a left-sided hemiparesis and facial asymmetry. After removal of the patient's orthodontic appliance, magnetic resonance (MR) imaging and MR angiography of the brain confirmed completed infarction of approximately one-half of the right MCA territory due to a focal pseudoocclusion (high-grade stenosis causing near occlusion) in the distal M1 at the MCA bifurcation []. Endovascular revascularization was felt to be a poor option due to the >24-hour duration of symptoms prior to neurosurgical involvement, completed nature of the infarction, and large volume of MCA territory involved []. Because endovascular revascularization would not be pursued, in conjunction with the high-quality noninvasive imaging findings and the need to minimize pediatric exposure to ionizing radiation, diagnostic cerebral angiography was not pursued. A trial of heparin was initiated instead because the patient still had preserved speech, implying at-risk MCA territory. However, the heparin infusion was halted due to early signs of hemorrhagic transformation in the ischemic infarct. Subsequently, a decompressive craniectomy was performed due to increasing mass effect from the progression of stroke causing increased lethargy and left-sided hemiplegia [Figures and ]. After decompression, the patient's examination improved such that she was fluent with an age-appropriate level of consciousness and had moderate left-sided hemiparesis; her facial asymmetry persisted.\nOn postoperative day 3 after the decompressive craniectomy, 5 days after original presentation and MR angiography documenting the M1 pseudoocclusion, the patient became acutely comatose with right-sided mydriasis. CT angiography of the head revealed a ruptured 19 × 16 mm mycotic aneurysm arising from the M1 occlusion site, associated with a large intracerebral hemorrhage and midline shift [Figures –]. While the operating room was being prepared for a hematoma evacuation, the patient was taken to the endovascular suite for emergent coil embolization. Given completion of the M1 occlusion, extension of the MCA infarction, and rapid growth of the pseudoaneurysm, both parent vessel and pseudoaneurysm were rapidly coiled to complete obliteration [Figures –]. From the endovascular suite, the patient was taken directly to the operating room for hematoma evacuation []. After emergency interventions were completed, pupil function was restored and standard intracranial pressure management ensued. Ultimately, she was discharged home with intact speech, cognitive function appropriate for age, and residual left hemiparesis.