Case presentation
A 45-year-old female was referred to our hospital with headache, nausea,
and vomiting, followed by mental changes in the morning. She was
diagnosed with MMD ten years previously. Initially, non-contrast
computed tomography (CT) of the brain revealed a left dominant
intraventricular hemorrhage (IVH) with hydrocephalus, scant subarachnoid
hemorrhage along both frontal sulci and diffuse brain parenchymal
swelling (Figure 1a). For emergency cerebrospinal fluid (CSF) diversion,
the patient was referred to the neurosurgery department, and her
consciousness recovered immediately after extraventricular drainage.
Digital subtraction angiography (DSA) revealed bilateral MMD and the
prominent development of a choroidal anastomosis (ChA) originating from
the left lateral posterior choroidal artery (LPChA). The ChA involved a
small pseudoaneurysm, which was considered the culprit lesion for the
bleeding (Figure 1b-c). The postcontrast high-resolution vessel wall
image (HR-VWI) demonstrated strong wall enhancement of the
pseudoaneurysm, indicating the rupture point of the aneurysm.
A superficial temporal artery-middle cerebral artery (STA-MCA) bypass
was performed to reduce the ChA and banish the pseudoaneurysm (Figure
1d). Immediate post-bypass indocyanine green angiography confirmed the
patency of the anastomosis; however, extensive brain swelling was
observed in the surgical field 20 min after the bypass. The surgical
procedure for the bony defect was completed. Postoperative magnetic
resonance imaging (MRI) revealed multiple microbleeds, T2 white matter
changes in the left frontotemporal area, and external brain herniation
via the craniectomy site (Figure 2a). A neurological examination
revealed motor aphasia and paresis of the right hand. Post-bypass brain
single photon emission computed tomography (SPECT) revealed
hyperperfusion in the left MCA territory (Figure 2b). Intensive blood
pressure control was achieved with the administration of a hyperosmolar
agent to prevent hemorrhage expansion and progression of hyperperfusion
syndrome.
The patient complained of severe headache, nausea, and vomiting
postoperatively. Brain CT revealed a left dominant IVH, suggesting
rebleeding from the pseudoaneurysm. The second DSA revealed significant
growth of the pseudoaneurysm and non-patent flow of the bypass (Figure
3a-d). The patient underwent emergency coil embolization for a ruptured
pseudoaneurysm under general anesthesia. A 6Fr guiding catheter (DA-XB
Envoy, CERENOVUS, Le Locle, Switzerland) was placed into the distal
cervical left vertebral artery (V3), and a microcatheter (Excelsior®
SL-10® pre-shaped 45, Stryker, Cork, Ireland), advanced over an 0.010
inch microguidewire (Synchro®, Stryker, Salt lake city, USA) into the
distal left LPChA. The resulting super selective angiogram revealed a 13
mm pseudoaneurysm in the distal choroidal portion of the left LPChA and
the medullary tributaries distal to the aneurysm (Figure 3e). Coil
embolization was then carefully conducted under fluoroscopic observation
with five coils (Axium™ Prime 8 mm x 20 cm, ev3™, Irvine, USA / Target®
360 ULTRA 5 mm x 10 cm, 4.5 mm x 10 cm, 4 mm x 10 cm, Stryker, Cork,
Ireland / Target® HELICAL NANO™ 2.5 mm x 4 cm, Stryker, Cork, Ireland).
During coil embolization, we attempted to preserve the flow of the
medullary tributaries distal to the aneurysm due to the risk of LPChA
territory infarction (Figure 3f). The patient’s immediate postoperative
period was uneventful. The patient underwent a second STA-MCA bypass to
minimize the medullary tributaries of the ChA (Figure 2c-d), and the
postoperative course was uneventful. Follow-up DSA revealed no
recanalization of the pseudoaneurysm, the disappearance of the ChA, or
patent bypass (Figure 3g-h). Strict blood pressure control was achieved,
and the clinical symptoms gradually improved within a week. The patient
was discharged after an additional two-week course of conservative
management. The right hand paresis had fully resolved by the three-month
follow-up, but mild aphasia persisted. At the four-month follow-up, MRI
showed signal intensity normalization of the T2 white matter high-signal
lesion (Figure 2e). At the six-month follow-up, patent flow of the
bypass was confirmed by cerebral angiography (Figure 3h).