Delayed appearance of basilar trunk small atypical aneurysms in nontraumatic, initially angiogram-negative subarachnoid hemorrhage: A report of three patients

Abstract

Background: Repeat angiography will identify vascular pathology in approximately 10% of cases following angiogram-negative subarachnoid hemorrhage (anSAH), but small atypical aneurysms of the basilar artery are very uncommon.

Objective: To report a case series of delayed appearance of nontraumatic basilar artery small atypical aneurysms.

Methods: IRB approval was obtained for this retrospective case series and patient consent was waived.

Results: Herein we report three cases of spontaneous anSAH, all of whom had a negative digital subtraction angiogram (DSA) on admission and all of whom had appearance of a small atypical aneurysms of the upper basilar trunk/apex on follow-up imaging (two during the initial admission and one in a delayed fashion). All three patients were ultimately treated with flow diversion (although one patient underwent attempted coiling that was abandoned due to inability to catheterize the aneurysm).

Conclusion: This report highlights the importance of a repeat DSA in cases of anSAH as well as the importance of scrutinizing the basilar trunk for these very small atypical aneurysms that may go unnoticed.

Keywords: Angiogram-negative subarachnoid hemorrhage; flow diversion; perimesencephalic SAH; pseudoaneurysm.

Figure 1.

A 51-year-old male (patient 1) presenting with headache and neurological decline. Axial view of the noncontrast head CT showing (a) IVH with obstructive hydrocephalus, (b) pontine ICH, and (c) SAH in the prepontine cistern. CT: computed tomography; ICH: intracerebral hemorrhage; IVH: intraventricular hemorrhage; SAH: subarachnoid hemorrhage.

Figure 2.

(a–c) Initial DSA of patient 1. (a) AP view and (b) lateral view of the cerebral angiogram of the left vertebral artery, negative for aneurysm or vascular abnormality. (c) Zoomed in lateral view of the cerebral angiogram of the left vertebral artery, focused on distal basilar artery that is negative for aneurysm. (d–f) Repeat DSA of patient 1. (d) AP view and (e) lateral view of the cerebral angiogram of the left vertebral artery revealing a newly formed small atypical of the posterior aspect of the basilar apex. (f) Immediate postflow diversion lateral view of the cerebral angiogram showing stagnation of flow within the aneurysm. AP: anterior posterior; DSA: digital subtraction angiogram.

Figure 3.

A 54-year-old female (patient 2) presenting with sudden onset of headache and altered mental status. Axial view of the noncontrast head CT showing (a) obstructive hydrocephalus, (b) SAH in the interpeduncular cistern and bilateral sylvian cisterns, and (c) SAH in the prepontine cistern and fourth ventricular IVH. CT: computed tomography; IVH: intraventricular hemorrhage; SAH: subarachnoid hemorrhage.

Figure 4.

(a–c) Initial DSA of patient 2. (a) AP view and (b) lateral view of the cerebral angiogram of the right vertebral artery, negative for aneurysm or vascular abnormality. (c) Three-dimensional reconstruction of the right vertebral artery injection focused on the basilar artery that is negative for aneurysm. (d–f) Repeat DSA of patient 2. (d) AP view and (e) lateral view of the cerebral angiogram of the left vertebral artery revealing a newly formed small atypical of the posterior aspect of the basilar trunk. (f) Immediate postflow diversion lateral view of the cerebral angiogram showing stagnation of flow within the pseudoaneurysm. (g–h) Follow-up DSA of patient 2. (g) AP view and (h) lateral view of the cerebral angiogram of the right vertebral artery with no residual aneurysm. AP: anterior posterior; DSA: digital subtraction angiogram.

Figure 5.

A 42-year-old female (patient 3) presenting with sudden onset of headache and mild confusion. Axial view of the noncontrast head CT showing (a) no signs of obstructive hydrocephalus, (b) SAH in the interpeduncular cistern and bilateral sylvian cisterns, and (c) SAH in the prepontine cistern. CT: computed tomography; SAH: subarachnoid hemorrhage.

Figure 6.

(a–b) Initial DSA of patient 3. (a) AP view and (b) lateral view of the cerebral angiogram of the left vertebral artery, negative for aneurysm or vascular abnormality. (c–e) Repeat DSA of patient 3. (c) AP view, (d) lateral view, and (e) three-dimensional reconstruction of the cerebral angiogram of the left vertebral artery revealing a newly formed small atypical aneurysm of the posterior aspect of the basilar trunk, near the apex. AP: anterior posterior; DSA: digital subtraction angiogram.