Anatomical and physiological experiments in the lamprey reveal the neural circuit involved in transforming olfactory inputs into motor outputs, which was previously unknown in a vertebrate.

The Pipeline embolization device (PED) is the most widely used flow diverter in endovascular neurosurgery. In 2011, the device received FDA approval for the treatment of large and giant aneurysms in the internal carotid artery extending from the petrous to the superior hypophyseal segments. However, as popularity of the device grew and neurosurgeons gained more experience, its use has extended to several other indications. Some of these off-label uses include previously treated aneurysms, acutely ruptured aneurysms, small aneurysms, distal circulation aneurysms, posterior circulation aneurysms, fusiform aneurysms, dissecting aneurysms, pseudoaneurysms, and even carotid-cavernous fistulas. The authors present a literature review of the safety and efficacy of the PED in these off-label uses.

OBJECTIVE The overall risk of ischemic stroke from a chronically occluded internal carotid artery (COICA) is around 5%-7% per year despite receiving the best available medical therapy. Here, authors propose a radiographic classification of COICA that can be used as a guide to determine the technical success and safety of endovascular recanalization for symptomatic COICA and to assess the changes in systemic blood pressure following successful revascularization. METHODS The radiographic images of 100 consecutive subjects with COICA were analyzed. A new classification of COICA was proposed based on the morphology, location of occlusion, and presence or absence of reconstitution of the distal ICA. The classification was used to predict successful revascularization in 32 symptomatic COICAs in 31 patients, five of whom were female (5/31 [16.13%]). Patients were included in the study if they had a COICA with ischemic symptoms refractory to medical therapy. Carotid artery occlusion was defined as 100% cross-sectional occlusion of the vessel lumen as documented on CTA or MRA and confirmed by digital subtraction angiography. RESULTS Four types (A-D) of radiographic COICA were identified. Types A and B were more amenable to safe revascularization than types C and D. Recanalization was successful at a rate of 68.75% (22/32 COICAs; type A: 8/8; type B: 8/8; type C: 4/8; type D: 2/8). The perioperative complication rate was 18.75% (6/32; type A: 0/8 [0%]; type B: 1/8 [12.50%]; type C: 3/8 [37.50%], type D: 2/8 [25.00%]). None of these complications led to permanent morbidity or death. Twenty (64.52%) of 31 subjects had improvement in their symptoms at the 2-6 months' follow-up. A statistically significant decrease in systolic blood pressure (SBP) was noted in 17/21 (80.95%) patients who had successful revascularization, which persisted on follow-up (p = 0.0001). The remaining 10 subjects in whom revascularization failed had no significant changes in SBP (p = 0.73). CONCLUSIONS The pilot study suggested that our proposed classification of COICA may be useful as an adjunctive guide to determine the technical feasibility and safety of revascularization for symptomatic COICA using endovascular techniques. Additionally, successful revascularization may lead to a significant decrease in SBP postprocedure. A Phase 2b trial in larger cohorts to assess the efficacy of endovascular revascularization using our COICA classification is warranted.

Odor-guided behaviors, including homing, predator avoidance, or food and mate searching, are ubiquitous in animals. It is only recently that the neural substrate underlying olfactomotor behaviors in vertebrates was uncovered in lampreys. It consists of a neural pathway extending from the medial part of the olfactory bulb (medOB) to locomotor control centers in the brainstem via a single relay in the caudal diencephalon. This hardwired olfactomotor pathway is present throughout life and may be responsible for the olfactory-induced motor behaviors seen at all life stages. We investigated modulatory mechanisms acting on this pathway by conducting anatomical (tract tracing and immunohistochemistry) and physiological (intracellular recordings and calcium imaging) experiments on lamprey brain preparations. We show that the GABAergic circuitry of the olfactory bulb (OB) acts as a gatekeeper of this hardwired sensorimotor pathway. We also demonstrate the presence of a novel olfactomotor pathway that originates in the non-medOB and consists of a projection to the lateral pallium (LPal) that, in turn, projects to the caudal diencephalon and to the mesencephalic locomotor region (MLR). Our results indicate that olfactory inputs can induce behavioral responses by activating brain locomotor centers via two distinct pathways that are strongly modulated by GABA in the OB. The existence of segregated olfactory subsystems in lampreys suggests that the organization of the olfactory system in functional clusters may be a common ancestral trait of vertebrates.

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OBJECTIVEThe Pipeline embolization device (PED) has become a valuable tool in the treatment of cerebral aneurysms. Although failures with PED treatment have been reported, the characteristics and course of these aneurysms remain a topic of uncertainty.METHODSElectronic medical records and imaging studies were reviewed for all patients treated with the PED between July 2010 and March 2015 to identify characteristics of patients and aneurysms with residual filling after PED treatment.RESULTSOf 316 cases treated at a single institution, 281 patients had a long-term follow-up. A total of 52 (16.4%) aneurysms with residual filling were identified and constituted the study population. The mean patient age in this population was 58.8 years. The mean aneurysm size was 10.1 mm ± 7.15 mm. Twelve aneurysms were fusiform (23%). Of the aneurysms with residual filling, there were 20 carotid ophthalmic (CO) aneurysms (20% of all CO aneurysms treated), 10 other paraclinoid aneurysms (16.4% of all paraclinoid aneurysms), 7 posterior communicating artery (PCoA) aneurysms (21.9% of all PCoA aneurysms), 7 cavernous internal carotid artery (ICA) aneurysms (14.9% of all cavernous ICA aneurysms), 4 vertebrobasilar (VB) junction aneurysms (14.8% of all VB junction aneurysms), and 3 middle cerebral artery (MCA) aneurysms (25% of all MCA aneurysms). Eleven patients underwent placement of more than one PED (21.2%), with a mean number of devices of 1.28 per case. Eight of 12 aneurysms were previously treated with a stent (15.4%). Nineteen patients underwent re-treatment (36.5%); the 33 patients who did not undergo re-treatment (63.5%) were monitored by angiography or noninvasive imaging. In multivariate analysis, age older than 65 years (OR 2.65, 95% CI 1.33–5.28; p = 0.05), prior stent placement across the target aneurysm (OR 2.94, 95% CI 1.15–7.51; p = 0.02), aneurysm location in the distal anterior circulation (MCA, PCoA, and anterior choroidal artery: OR 2.72, 95% CI 1.19–6.18; p = 0.017), and longer follow-up duration (OR 1.06, 95% CI 1.03–1.09; p < 0.001) were associated with incomplete aneurysm occlusion.CONCLUSIONSWhile the PED can allow for treatment of large, broad-necked aneurysms with high efficacy, treatment failures do occur (16.4%). Aneurysm size, shape, and previous treatment may influence treatment outcome.

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