Stereotactic radiosurgery (SRS) with >5 fractions (fr) has been increasingly adopted to improve local control and safety for brain metastases (BM) of >10 cm 3 , given the limited brain tolerance of SRS with ≤5 fr. However, the optimal indication and treatment design, including the prescribed dose and distribution for 10 fr SRS, remains uncertain. A single fr of 24 Gy provides approximately 95% of the one-year local tumor control probability. The potential SRS doses in 10 fr that is clinically equivalent to a single fr of 24 Gy regarding anti-tumor effect range from 48.4 to 81.6 Gy as biological effective doses (BED) as a function of the BED model formulas along with the alpha/beta ratios. The most appropriate BED formula in conjunction with an alpha/beta ratio to estimate similar anti-BM effects for single and 10 fr remains controversial.Herein, we describe four cases of symptomatic radiation-naïve BM >10 cm 3 (range, 11 to 26 cm 3 ), treated with 10 fr SRS with a standard prescribed dose of 42 Gy, for which modified dynamic conformal arcs were used with forward planning to improve dose conformity. In the first two cases with gross tumor volumes (GTV) of 15.3 and 10.9 cm 3 , 42 Gy was prescribed to 70%-80% isodose, normalized to 100% at the isocenter, which encompasses the boundary of the planning target volume: GTV + isotropic 1 mm margin. The tumor responses were initially marked regression followed by regrowth within three months in case 1 and no shrinkage with subsequent progression within three months in case 2. In the remaining two cases with larger GTVs of 19.1 and 26.2 cm 3 , the GTV boundary and 2-3 mm margin-added object volume was covered by 80% and 56% isodoses with 53 Gy and 37 Gy, respectively, to further increase the marginal and internal doses of GTV and to ensure moderate dose spillage outside the GTV, while >1-1.5 mm outside the GTV was covered by 42 Gy with 63% isodose. According to the BED based on the linear-quadratic (LQ) model with an alpha/beta ratio of 10 (BED 10 ), 53 Gy corresponds to approximately 81 Gy in BED 10 and 24 Gy in a single fr.Excellent initial maximum tumor response and subsequently sustained tumor regression (STR) were achieved in both cases. Subsequently, enlarging nodules that could not exclude the possibility of tumor regrowth were disclosed within two years, while late adverse radiation effects remained moderate.These dose-effect relationships suggest that a GTV marginal dose of ≥53 Gy with ≤80% isodose would be preferred to effect ≥1-year STR and that further dose escalation of both marginal and internal GTV may be necessary to achieve ≥2-year STR, while GTV of >25 cm 3 may be unsuitable for 10 fr SRS in terms of longterm brain tolerance. Among LQ, LQ-cubic, and LQ-linear model formulas and alpha/beta ratios of 10-20, BED 10 may be clinically most suitable to estimate a 10 fr SRS dose that provides anti-BM efficacy similar to that for a single fr.

We report a very rare case of a ruptured intracranial anterior spinal artery (ASA) aneurysm. A 66-year-old man presented with gradually deteriorating occipitalgia and mild conscious disturbance. He had a history of hypercholesteremia and diabetes mellitus. There was no evidence of collagen disease or inflammation reaction in his physical examination and laboratory data. The first computed tomography (CT) scan revealed thick subarachnoid hemorrhage (SAH) in front of the brain stem with a little intraventricular clot. However, the cerebral angiography (CAG) showed no apparent aneurysm other than right vertebral artery (VA) occlusion with collateral circulation. Repeat cerebral angiography gradually disclosed the presence of an ASA aneurysm. Therefore, the ASA aneurysm was clipped through the right lateral suboccipital approach under trans-cranial motor evoked potential (MEP) monitoring on Day 61.The amplitude of MEP did not decrease during the operation. The patient did not neurologically deteriorate after surgery. It is previously reported that spinal artery aneurysm should be treated by direct or endovascular surgery because of the risk of rupture. However, recent reports showed that spinal artery aneurysm sometimes regressed spontaneously if it is not flow related. In this case, because of the right vertebral artery occlusion, the fenestrated ASA received hemodynamic stress by collateral circulation.Ruptured aneurysm of the spinal artery requires precise diagnosis and meticulous handling depending on the individual pathogenesis.

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Failed coil embolization of cerebral aneurysms may be occasionally followed by direct surgical treatment. We had 5 patients who underwent coil retrieval and surgical clipping after coil embolization because of periprocedural complications. The patients, ranging in age from 40 to 71, had wide-neck aneurysms located at the anterior communicating artery (AcomA) in 3 patients, the middle cerebral artery (MCA) in 1, and the internal carotid-ophthalmic artery (IC-Ophthalmic) in 1. They were embolized with Guglielmi detachable coils (GDCs), which had to be retrieved within 8 days because of coil protrusion and migration in 3 patients, aneurysm rupture in 1, and increased mass effect due to coil compaction in 1. Coils were successfully removed with aneurysmotomy or arteriotomy under temporary trapping, aneurysms were then clipped or trapped. Three patients had a good outcome, but one suffered permanent visual disturbance and the other had a motor deficit. Our study revealed that a small AcomA aneurysm had a high risk of complication in a case of complex anatomy of the AcomA-A1-A2 complex with its difficult access. In addition, insufficient packing of the inflow zone in a large and symptomatic aneurysm may cause coil compaction and regrow with increasing mass effect. The indication and treatment strategy for these aneurysms should be carefully determined.

Measurement of cerebral blood flow in cerebral endovascular procedures is useful for the assessment of treatment effects. We used transcranial Doppler sonography (TCD) and Doppler guide wires (SmartWire®, Cardiometrics Co.) in intravascular treatment. The cases were 6 brain arteriovenous malformations (AVM), 2 carotid cavernous fistulas (CCF), 2 facial angiomas, and 2 carotid stenoses. Intravascular cerebral blood flow measurements with the SmartWire were performed during the endovascular procedure. TCD was used pre- and post-endovascular treatment, and velocity, pulsatility index (PI) and resistance index (RI) were compared with the SmartWire. For both TCD and SmartWire, blood velocity of the main artery decreased, and PI and RI were improved after embolisation of AVM. In angioplasty cases, post stenotic flow velocity, as measured by SmartWire, was improved, and the flow of MCA measured with TCD was also improved after treatment. The SmartWire is useful to assess cerebral blood flow changes during the neuroendovascular procedure. Combined with repeated follow up with TCD, Doppler flow measurements are useful to assess the effect of endovascular treatment.