Should posterior cerebral artery occlusions be recanalized? Insights from the Trevo Registry.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the safety and effectiveness of mechanical thrombectomy (MT) in patients with acute ischaemic stroke related to isolated and primary posterior cerebral artery (PCA) occlusions amongst the patients enrolled in the multicentre post-market Trevo Registry. METHOD: Amongst the 2008 patients enrolled in the Trevo Registry with acute ischaemic stroke due to large vessel occlusion treated by MT, 22 patients (1.1%) [10 females (45.5%), mean age 66.2 ± 14.3 years (range 28-91)] had a PCA occlusion [17 P1 (77.3%) and five P2 occlusions (22.7%)]. Recanalization after the first Trevo (Stryker, Fremont, CA, USA) pass and at the end of the procedure was rated using the modified Thrombolysis in Cerebral Infarction (mTICI) score. Procedure-related complications (i.e. groin puncture complication, perforation, symptomatic haemorrhage, embolus in a new territory) were also recorded. The modified Rankin Scale at 90 days was assessed. RESULTS: Median National Institutes of Health Stroke Scale at admission was 14 (interquartile range 8-16). Stroke aetiology was cardio-embolic in 68.2% of cases. Half of the patients (11/22) received intravenous tissue plasminogen activator. 54.5% of the patients were treated under general anaesthesia. Reperfusion (i.e. mTICI 2b or 3) after first pass was obtained in 65% of cases. Final mTICI 2b-3 reperfusion was obtained in all cases. Only one (4.5%) procedure-related complication was recorded (puncture site) that resolved after surgery. At 90-day follow-up, modified Rankin Scale 0-2 was obtained in 59% of the patients and 9.1% died within the first 3 months after MT. CONCLUSION: Mechanical thrombectomy for PCA occlusions seems to be safe (<5% procedure-related complications) and effective. Larger repository datasets are needed.

A review of size and location of ruptured intracranial aneurysms.

OBJECTIVE: To review our experience and examine the size at which aneurysms ruptured in our patient population. METHODS: Patient charts and angiograms for all patients admitted with a diagnosis of subarachnoid hemorrhage to the Thomas Jefferson/Wills Eye Hospital between April 1996 and March 2000 were reviewed. RESULTS: Of the 362 cases reviewed, definite measurements of the ruptured aneurysm were obtained in 245. The data clearly showed that most ruptured aneurysms presenting to our institution were less than 10 mm in diameter. We found that, regardless of location on the circle of Willis, 85.6% of all aneurysms presenting with rupture were less than 10 mm. Review by location shows that aneurysms of the anterior communicating artery most often presented with rupture at sizes less than 10 mm (94.4%). A large number of ruptured posterior communicating artery aneurysms also presented at sizes less than 10 mm (87.5%). This trend continued for all aneurysm sites in our review. The incidence of subarachnoid hemorrhage in Western countries is estimated at 10 per 100,000 people per year. Recent reports have indicated that aneurysms less than 10 mm in size are unlikely to rupture. CONCLUSION: We argue that the risk of small aneurysms rupturing is not insignificant, especially those of the anterior communicating artery. Our findings indicate that surgery on unruptured aneurysms should not be predicated on aneurysm size alone.

Diagnosis and therapy for pituitary tumors.

This article focuses on developments in treatment options for pituitary adenomas. We review the literature on the advances in diagnosis and treatment modalities, including medical and surgical approaches. We also discuss conventional radiation and the recently proposed genetic treatments for pituitary tumors.

Neuropeptide Y and dynorphin-immunoreactive large dense-core vesicles are strategically localized for presynaptic modulation in the hippocampal formation and substantia nigra.

Neuropeptide Y (NPY) and dynorphin elicit regionally selective presynaptic modulation in the hippocampal formation and the pars reticulata of the substantia nigra, respectively. We examined potential anatomical substrates for their presynaptic modulation by determining the distribution and size of large (80-120 nm) dense-core vesicles (DCVs), organelles previously shown to be immunoreactive for each peptide. Throughout the hippocampal formation, NPY-immunoreactive DCVs were located primarily in axon terminals and were more sparingly distributed in dendrites. In comparison with other portions of the hippocampal formation, NPY-labeled DCVs were most abundant in axons and terminals of the CA1 region. The DCVs in the CA1 region of the hippocampus also more frequently had larger mean cross-sectional diameters when located along portions of the terminal in contact with unlabeled axons. In both the CA1 region of the hippocampus and the dentate gyrus, NPY-labeled DCVs in contact with portions of the axonal membrane apposed to astrocytes also were larger than those located more centrally in the axon terminal. Dynorphin-immunoreactive DCVs in axon terminals of the substantia nigra were significantly larger when found near portions of the axonal membrane in contact not only with other axons and astrocytic processes, but also occasionally with postsynaptic dendrites. The parallels between diameters of DCVs and known selectivity of NPY for presynaptic modulation in the CA1 region of the hippocampus suggest a direct correlation between the size and distribution of immunoreactive DCVs and their sites of exocytotic release.(ABSTRACT TRUNCATED AT 250 WORDS)

Septohippocampal neurons in the rat septal complex have substantial glial coverage and receive direct contacts from noradrenaline terminals.

The ultrastructure of septohippocampal neurons in the septal complex and their relations with catecholamine, principally noradrenaline, terminals were examined in single thin sections. Projection neurons were identified by retrograde transport of wheat-germ agglutinated apo-horseradish peroxidase conjugated to colloidal gold particles (WAHG) following an injection into the hippocampal formation of anesthetized adult rats. After a 1 day survival, sections through the septal complex were labeled with antibodies to tyrosine hydroxylase (TH) or dopamine-beta-hydroxylase (DBH). By light microscopy, numerous processes with TH- and DBH-immunoreactivity were near neurons containing retrogradely transported WAHG. By electron microscopy, most WAHG was associated with lysosomes, multivesicular and 'sequestration' bodies in the cytoplasm of perikarya and large dendrites. WAHG-labeled perikarya (n = 114) had a large amount of astrocytic coverage (> 60% of surface) and a low amount of terminal coverage (< 25%). WAHG-labeled perikarya and dendrites were either directly contacted by TH- or DBH-labeled terminals or abutted glial processes apposed to TH- or DBH-labeled terminals. Immunoreactivity for TH and DBH was found primarily in axons and axon terminals. The morphology and synaptic associations of TH-labeled terminals was similar to that reported previously. DBH-labeled terminals (n = 314; 0.5 +/- 0.2 microns in diameter) contained numerous small clear vesicles and from 0-4 large, dense-core vesicles. DBH-containing terminals: (1) contacted perikarya and dendrites (58%), 10% of which contained WAHG; (2) were closely apposed to other terminals (7%); or (3) were separated by glial processes (35%). DBH-labeled terminals formed chiefly symmetric synapses on perikarya. However, most DBH-containing terminals formed both asymmetric and symmetric synapses on the shafts of small dendrites, suggesting both excitatory and inhibitory functions for noradrenaline terminals on septal neurons. The results demonstrate that septohippocampal neurons (1) are mostly engulfed by astrocytes and have very little terminal coverage; (2) are both directly contacted (synapses) and indirectly contacted (appositions to apposing astrocytes or axon terminals) by catecholamine, particularly noradrenaline, terminals.

Serotonin-containing terminals synapse on septohippocampal neurons in the rat.

Serotonin [5-hydroxytryptamine (5-HT)] is thought to be involved in mnemonic functions and dysfunctions possibly by directly contacting neurons in the medial septal and diagonal band nuclei (i.e., the septal complex) that project to the hippocampal formation. However, there is no cellular substrate for this modulation. Thus, we examined the ultrastructure and synaptic associations of 5-HT-containing terminals in relation to septohippocampal neurons in the septal complex of the rat brain. Projection neurons were identified by retrograde transport of wheat germ agglutinated apo-horseradish peroxidase conjugated to colloidal gold particles (WAHG) following an injection into the ventral hippocampal formation of anesthetized adult rats. After a 1 day survival, sections through the septal complex were labeled with antibodies to 5-HT. By light microscopy, numerous processes with 5-HT immunoreactivity (5-HT-I) were observed in close proximity to neurons containing retrogradely transported WAHG. By electron microscopy, 5-HT-I was found exclusively in axons and axon terminals. Axons were primarily unmyelinated. Terminals with 5-HT-I were 0.35-1.2 microns in diameter and contained numerous small, clear vesicles and 0-4 large, dense-core vesicles. The 5-HT-labeled terminals: 1) contacted perikarya and dendrites (220 of 349); 2) were closely apposed to other terminals (25 of 349); or 3) had no neuronal contacts in the plane of section analyzed (104 of 349). The 5-HT-labeled terminals formed exclusively symmetric synapses on perikarya; some of these perikarya as well as some large dendrites similarly contacted by the 5-HT-labeled terminals also contained WAHG affiliated with lysosomes and multivesicular and "sequestration" bodies in the cytoplasm. However, the majority of terminals with 5-HT-I formed contacts on the shafts of small unlabeled dendrites (69% of 220); most of these were characterized as either asymmetric synapses or appositions not separated by astrocytes in the plane of section analyzed. We conclude that 5-HT-containing terminals in the rat septal complex: 1) directly modulate septohippocampal and other neurons through symmetric (potentially inhibitory) synapses on soma and proximal dendrites; and 2) form primarily asymmetric (potentially excitatory) synapses with distal (small) dendrites from neurons of unidentified origin. These findings suggest that serotonin may affect learning and memory through modulation of septal efferents to the hippocampal formation and may have direct relevance to the neuropathological basis for Alzheimer's disease.

Septal efferent axon terminals identified by anterograde degeneration show multiple sites for modulation of neuropeptide Y-containing neurons in the rat dentate gyrus.

The ultrastructure and cellular associations of septal efferent terminals identified by anterograde degeneration with neurons containing neuropeptide Y (NPY) in the rat dentate gyrus were examined quantitatively. For this, the septal complex (i.e., medial septal and diagonal band nuclei) of adult male rats was injected with the neurotoxin ibotenic acid (1%; 150 nl) and following a 2-4-day survival period, the hippocampal formation was processed for the electron microscopic immunocytochemical demonstration of NPY using the avidin-biotin complex method. Terminals with the morphological characteristics of anterograde degeneration, in particular an increase in osmiophilia, and neurons containing NPY-like immunoreactivity (NPY-LI) were most abundant in the hilus of the dentate gyrus. In this region, degenerating terminals (n = 109) were usually small (0.2-0.4 microns in diameter) and formed both asymmetric and symmetric synapses with small (distal) dendrites. The degenerating terminals contacted either single NPY-containing (19%) perikarya or dendrites or unlabeled (48%) perikarya or dendrites. Some degenerating terminals contacted the same perikarya or dendrites as an NPY-containing terminal (11%); these neurons were either immunoreactive for NPY or unlabeled. The remaining degenerating terminals were either directly apposed without glial intervention to unlabeled and NPY-labeled terminals (11%) or lacked associations with any neuronal processes in the plane of section analyzed (11%). The findings demonstrate that ibotenic acid injections in the septal complex can identify septal efferent terminals by degeneration and provide cellular substrates for the direct synaptic regulation as well as presynaptic modulation of hippocampal NPY-containing neurons by septal efferent terminals.

Ultrastructural localization of neuropeptide Y-like immunoreactivity in the rat hippocampal formation.

Neuropeptide Y (NPY) has been implicated in the modulation of hippocampal neuronal activity and in the pathophysiology of several neurological disorders involving the hippocampal formation. Thus, this study examines the light and electron microscopic immunoperoxidase labeling of a rabbit polyclonal antibody against porcine NPY in single sections through each lamina of the CA1 and CA3 regions of the hippocampus and the dentate gyrus (DG) of normal adult rats. By light microscopy, the majority of perikarya with intense NPY-like immunoreactivity (NPY-LI) were located in stratum oriens of CA1 and CA3 of the hippocampus and in the hilus of the DG. Fine varicose processes with NPY-LI were found in all layers of the hippocampal formation, but were densest in the outer third of the molecular layer of the DG. The density of NPY-labeling was greater in the ventral portion of the hippocampal formation. By electron microscopy, most NPY-containing perikarya in all three hippocampal regions were: small (8-12 microns) or medium-sized (12-18 microns) and elongated; or medium-sized and round. A dense accumulation of NPY-LI was commonly observed within the individual saccules of Golgi complexes and some rough endoplasmic reticulum in the cytoplasm. Perikarya and dendrites with NPY-LI usually were directly apposed to other neuronal processes (mostly terminals) and lacked astrocytic appositions. The majority of terminals in contact with NPY immunoreactive neurons were unlabeled and synapsed with the shafts of large and small dendrites. In CA1 and CA3 of the hippocampus, the types of synapses formed by the unlabeled terminals were not significantly different; however, more asymmetric synapses than symmetric synapses were formed by the unlabeled terminals on the shafts of small NPY-labeled dendrites in the DG. The terminals with NPY-LI (0.25-1.2 microns) contained many small, clear vesicles and 0-2 large, dense-core vesicles. The types of synapses (i.e., asymmetric and symmetric) and distribution of NPY-labeled terminals on the targets were remarkably similar in each lamina of the hippocampal subregions. The NPY-labeled terminals usually synapsed with one unlabeled perikaryon or dendrite. However, others synapsed either (1) with two unlabeled perikarya or dendrites simultaneously or (2) with one NPY-containing perikaryon or dendrite. Most of the terminals with NPY-LI formed symmetric junctions with the shafts of small (distal) dendrites.(ABSTRACT TRUNCATED AT 400 WORDS)