The natural history of aneurysms incompletely occluded by placement of a flow diverter: a multiinstitutional study

OBJECTIVE

Treatment of intracranial aneurysms by flow diversion is safe and effective and is increasingly popular. However, the correct treatment paradigm for aneurysms incompletely treated by initial placement of a flow diverter has not been established, nor have the subsequent natural history and occlusion rates of such aneurysms. The authors sought to outline the natural history of such aneurysms, which to date have been considered partially treated.

METHODS

The authors retrospectively reviewed consecutive cases from 6 high-volume neurointerventional services, including all cases in which the first follow-up imaging after placement of a flow diverter showed incomplete occlusion of the aneurysm, and for which subsequent clinical and/or radiological follow-up was available. All included patients were treated with the Pipeline Flex embolization device or the Pipeline Flex embolization device with Shield Technology. Subsequent radiographic and clinical outcome data were collected and analyzed using the Kaplan-Meier survival function.

RESULTS

A total of 263 patients with persistently patent aneurysms on first follow-up imaging after flow diversion were identified. Of these, 204 had clinical follow-up and 152 had additional imaging follow-up. Of this final cohort, 148 aneurysms were unruptured, and 4 were ruptured. The average aneurysm size by maximum dimension was 10.8 mm. The average recorded follow-up was 27.8 months in the cohort, with some patients followed for as long as 9 years from treatment. Over the course of 403 person-years of follow-up, no delayed aneurysm ruptures were recorded. Both with and without retreatment, aneurysms showed a trend toward progressive occlusion over time. Complications related to device placement were low.

CONCLUSIONS

Aneurysms that have been incompletely treated by flow diversion have a benign natural history with progression toward occlusion over time, with or without retreatment.

Predictors of angiographic resolution in patients with presumed reversible cerebral vasoconstriction syndrome

INTRODUCTION

Reversible cerebral vasoconstriction syndrome is a complex neurovascular syndrome that presents with varying neurological deficits as well as segmental vasoconstriction of the small and medium cerebral arteries. There is limited literature on pathologies that mimic reversible cerebral vasoconstriction syndrome, so this study aims to understand what factors may impact the angiographic confirmation of reversible cerebral vasoconstriction syndrome on follow-up and play a role in establishing the diagnosis.

METHODS

The Clinical Research Data Warehouse at this institution was employed to search the medical records for patients with diagnosis and treatment of reversible cerebral vasoconstriction syndrome between January 2010 and May 2021. After screening, 32 patients met the inclusion criteria for a presumed diagnosis of reversible cerebral vasoconstriction syndrome with both angiography on presentation and at three-month follow-up after treatment. Patients were divided into two categories: those with complete angiographic resolution, versus partial or no improvement on follow-up. Clinical and radiographic data were analyzed.

RESULTS

Patients who had partial or no resolution were more likely to have a history of hypertension (p = 0.001), higher systolic blood pressure on admission (p = 0.047), and present with a recurrent thunderclap headache (p = 0.038). Binary logistic regression selected for hypertension (odds ratio [OR] 18.35 [95% CI, 1.37-245.1]) as predictive of not having reversible cerebral vasoconstriction syndrome, as can be seen by partial or no resolution on follow-up angiography (p = 0.028).

CONCLUSION

Complete resolution on follow-up angiography is a distinguishing factor of reversible cerebral vasoconstriction syndrome. Our analysis revealed that a history of hypertension is the most significant predictor of confirming that a patient may not have reversible cerebral vasoconstriction syndrome. This is due, in part, to increased atherosclerotic or hypertensive cerebral arterial changes, which can mimic reversible cerebral vasoconstriction syndrome and present as partial or no resolution on angiography.

Vagal nerve stimulation for treatment-resistant depression: An update on mechanism of action and clinical use

Among few available therapeutic options for patients with treatment-resistant depression, chronic stimulation of the vagus nerve using an implanted stimulator, the so-called vagal nerve stimulation (VNS), has been shown to be both effective and safe technique, based on the multitude of studies. While the exact degree of its efficacy remains a subject of discussion, the strong scientific basis and a large body of data from completed and ongoing clinical trials suggest that VNS remains a viable option for those patients, who have exhausted less invasive treatment approaches.

Occlusion of Extracranial-Intracranial Bypass Anastomosis-Associated Aneurysms Following Contralateral High-Flow Extracranial-Intracranial Bypass in a Patient with Impaired Cerebrovascular Reserve

BACKGROUND AND IMPORTANCE

Extracranial-intracranial (EC-IC) bypass anastomosis-associated aneurysms are rare sequelae of cerebral revascularization surgery. Although treatment paradigms are not well defined, clipping, trapping with revision bypass, and donor vessel ligation represent the most common microsurgical approaches.

CLINICAL PRESENTATION

A 53-yr-old male presented with cognitive decline, left extremity weakness, and left visual field blurriness. Computed tomographic angiography of head/neck demonstrated bilateral cervical internal carotid artery occlusion and magnetic resonance imaging of brain showed a small right parieto-occipital lobe infarct. The patient's symptoms worsened despite aggressive medical management. Therefore, a right superficial temporal artery to middle cerebral artery (STA-MCA) bypass was performed for flow augmentation. Follow-up digital subtraction angiography (DSA) approximately 1 yr after surgery noted 2 new aneurysms adjacent to the patent STA-MCA anastomosis. Perfusion imaging at that time showed persistently reduced blood flow in the left cerebral hemisphere. A left STA-MCA bypass was performed, and intraoperative blood flow measurements showed this to be a high-flow bypass. Follow-up DSA 4 mo later demonstrated involution of the right STA-MCA bypass and occlusion of the anastomosis-associated aneurysms with increased perfusion of the right cerebral hemisphere via collateral blood flow from the patent high-flow left STA-MCA bypass. At 7 mo following left STA-MCA bypass, the patient's neurological examination remained stable and perfusion imaging showed improved blood flow in the left cerebral hemisphere.

CONCLUSION

We present a unique case in which a high-flow left EC-IC bypass with robust contralateral collateral blood flow was associated with subsequent occlusion of a right EC-IC bypass and 2 anastomosis-associated aneurysms in a patient with bilateral impaired cerebrovascular reserve.

Risk Factors for Distal Clot Migration during Mechanical Thrombectomy of Anterior Circulation Large Vessel Occlusion

Introduction: Distal clot migration (DCM) is a known complication of mechanical thrombectomy (MT), but neither risk factors for DCM nor ways of how it might affect clinical outcomes have been extensively studied to date. Methods: To identify risk factors for and outcomes in the setting of DCM, the records of all patients with acute ischemic stroke due to anterior circulation large vessel occlusion (LVO) treated with MT at a single center between May 2016 and June 2018 were retrospectively reviewed. Uni- and multivariable analyses were performed to evaluate predictors of DCM and good functional outcome (90-day modified Rankin Scale; mRS 0–2). Results: A total of 65 patients were included, DCM was identified in 22 patients (33.8%). Patients with DCM had significantly higher pre-procedural intravenous tissue plasminogen activator (IV-tPA) administration (81.8 vs. 53.5%, p = 0.03), stentrievers thrombectomy (95.5 vs. 62.8%, p = 0.006), and longer median puncture to recanalization time (44 [34–97] vs. 30 [20–56] min, p = 0.028) as compared to group with non-DCM. Also, they had lower rates of Thrombolysis in Cerebral Infarction (TICI) 2b/3 recanalization (p = 0.002), higher median National Institutes of Health Stroke Scale (NIHSS) scores at discharge (p = 0.01), and lower rates of 90-day mRS (0–2; 18.2 vs. 48.8%; p = 0.016). On subgroup analysis, patients with middle cerebral artery occlusions who underwent MT with stentrievers <40 mm in length had a higher risk of DCM (p = 0.026). On multivariable analysis, IV-tPA administration (OR; 5.019, 95% CI [1.319–19.102], p = 0.018) and stentrievers thrombectomy (OR; 10.031, 95% CI [1.090–92.344]; p = 0.04) remained significant predictors of DCM. Baseline NIHSS score (OR; 0.872, 95% CI [0.788–0.965], p = 0.008) and DCM (OR; 0.250, 95% CI [0.075–0.866], p = 0.03) were independent predictors of 90-day mRS 0–2. Conclusion: In patients undergoing MT for anterior circulation LVO, DCM is associated with lower rates of TICI 2b/3 recanalization and worse functional outcomes at 90 days. IV-tPA administration and MT with short stentrievers are independent predictors of DCM development.

Ratio of Arteriovenous Malformation Draining Vein to Adjacent Venous Sinus Diameter Is Associated with Increased Risk of Venous Stenosis

BACKGROUND

The development of venous outflow stenosis in cerebral arteriovenous malformation (AVM) is poorly understood. The location of stenosis within the AVM draining vein in relation to the adjacent venous sinus and the hypothesis that the ratio of draining vein to adjacent sinus diameter might predict the development of venous stenosis were explored.

METHODS

Patients with supratentorial AVMs (1997-2018) were reviewed (N = 290). AVM draining vein and adjacent venous sinus diameters, degree of draining vein stenosis, and distance from the maximal stenotic point to the junction of the adjacent draining sinus were recorded. Correlation between percentage of AVM draining vein stenosis and the ratio of AVM draining vein to venous sinus diameters was analyzed.

RESULTS

A total of 360 draining veins in 243 AVMs with complete angiographic data were measured. Venous stenosis (in 131 draining veins) was observed within 20 mm of the junction to the adjacent draining sinus in 85% of our sample. The ratio of draining vein to adjacent sinus diameter correlated positively with the percentage of venous stenosis (P < 0.01, r = 0.21). The ratio between 0.51-1.0 and >1.0 showed significant tighter stenosis compared with the ratio ≤0.5 (25.9% and 28.9% vs. 10.0%, respectively; P < 0.01).

CONCLUSIONS

AVM venous outflow stenosis is observed close to the adjacent venous sinus junction. The degree of venous stenosis is greater when the ratio of AVM draining vein/adjacent venous sinus diameter is >0.5. This may be related to more turbulent flow at the junction of the draining vein and venous sinus, especially in larger draining veins, which causes venous stenosis to develop over time.

Myocardial protection of insulin and potassium in a porcine ischemia-reperfusion model

BACKGROUND

We previously evaluated cardioprotective effects of glucose-insulin-potassium (GIK) in a porcine ischemia-reperfusion model; our results showed less myocardial pH decrease during ischemia and reperfusion and faster normalization of ATP and glucose during reperfusion. The proposed protective mechanism was facilitation of glucose transport for myocardial metabolism. The objective of this study was to assess the impact of insulin-potassium (IK) alone on myocardial metabolism.

METHODS

Male swine received continuous infusion of IK (IK group, n = 10), GIK (GIK group, n = 10), or standard lactated Ringer's (LR) solution (controls, n = 10). Induction of 20 minutes of ischemia in the left anterior descending (LAD) artery distribution was followed by 20 minutes of reperfusion. Real-time biosensors recorded pH and glucose levels in ischemic and nonischemic beds. Myocardial biopsies in the distribution of the LAD assessed ATP levels. Groups were compared using the Kruskal-Wallis and Mann-Whitney tests.

RESULTS

Real-time data are presented as percent change from baseline. At less than 10 minutes of ischemia, the average pH change was less for the IK group than the LR group (0.03% +/- 0.21% vs -2.06% +/- 1.23%; P = .001), and the pH change in the IK group was similar to the GIK group. After 10 minutes of ischemia and during the first 10 minutes of reperfusion, the IK group experienced pH changes that were similar to the LR group. Biopsies after 20 minutes of ischemia and 20 minutes of reperfusion showed less of a decline in ATP levels for the IK group compared to the LR group. Glucose at all time points demonstrated no statistically significant differences.

CONCLUSION

IK infusion alone demonstrates cardioprotective effects during early ischemia; however, compared to GIK infusion after 20 minutes of ischemia and reperfusion, myocardial pH and glucose levels were not sustained. Although insulin may facilitate glucose transport during ischemia, additional glucose in combination with IK enhances myocardial protection during reperfusion. This finding suggests that GIK enhancement during acute ischemia-reperfusion may improve myocardial protection.

Clinical effectiveness of a potassium chloride containing chewing gum in the treatment of hypersensitive teeth

Dental hypersensitivity has been observed in an increasing number of younger patients over the past few decades. The reasons for this include forced or false tooth-brushing techniques, and abrasions caused by bruxism or orthodontic procedures. The aim of the present study was to assess the possible benefits of a potassium chloride (KCl) containing chewing gum in dental hypersensitivity. The study population consisted of 59 selected university students (age: 25 +/- 4.4 years). Each subject suitable for entry into the study had more than 3 teeth sensitive to thermal stimulation (air stimulus range of 30-80 mm on a 100mm visual analogue scale (VAS), and showed signs of facial/cervical erosion, abrasion and/or gingival recession. Exclusion criteria were daily doses of medication, teeth with deep restorations, a gingival score of > 2, or periodontal surgery within the past 6 months. The total number of hypersensitive teeth was 217. Over a period of 3 weeks the subjects brushed with a non-desensitising toothpaste and, in addition, used the KCl chewing gum up to 6 times daily for 10 min on each occasion. This was followed by a period of 3 weeks of non-desensitising toothpaste use alone. The subjects were questioned on the severity of intraoral pain and asked to indicate the intensity of the pain on the VAS (baseline, 1, 3 and 6 weeks). Mean thermal sensitivity at baseline was 54.5 +/- 9 mm. There was a drop to 40.8 mm ( 1.9) after 1 week and to 28.6 mm (+/- 2) after 3 weeks. The reduction was statistically significant (p <0.001) at both measurement points. The mean rating increased to 29.1 mm after 6 weeks. The results of this study demonstrate that the daily use of a KCl containing chewing gum is a useful non-invasive method of reducing dental hypersensitivity over an extended period of time.

[Process of high performance training--exemplified by gymnastics]

A controlled, long-term training process, extensive medical treatment as well as a satisfying social and familiar environment are the key factors for a healthy development of young athletes in high level gymnastics.

Albert the Great's interpretation of neuropsychiatric symptoms in the context of scholastic psychology and physiology

Albert the Great (ca. 1193-1280) serves as an example to show how the Latin West successfully integrated Greco-Arabian psychology with Galenic physiology. He divised a model of perceptive, cognitive and mnestic powers located in different areas of the "brain cells" and interacting with the immaterial and man-specific intellect. He managed to describe anmesis, epileptic seizures and psychotic states as results of disturbed brain fuction. Finally, further aspects of Scholastic theorizing on mental disorders are discussed.

Localized frameshift mutation generates selective, high-frequency phase variation of a surface lipoprotein encoded by a mycoplasma ABC transporter operon

The wall-less mycoplasmas have revealed unusual microbial strategies for adaptive variation of antigenic membrane proteins exposed during their surface colonization of host cells. In particular, high-frequency mutations affecting the expression of selected surface lipoproteins have been increasingly documented for this group of organisms. A novel manifestation of mutational phase variation is shown here to occur in Mycoplasma fermentans, a chronic human infectious agent and possible AIDS-associated pathogen. A putative ABC type transport operon encoding four gene products is identified. The 3' distal gene encoding P78, a known surface-exposed antigen and the proposed substrate-binding lipoprotein of the transporter, is subject to localized hypermutation in a short homopolymeric tract of adenine residues located in the N-terminal coding region of the mature product. High-frequency, reversible insertion/deletion frameshift mutations lead to selective phase variation in P78 expression, whereas the putative nucleotide-binding protein, P63, encoded by the most 5' gene of the operon, is continually expressed. Mutation-based phase variation in specific surface-exposed microbial transporter components may provide an adaptive advantage for immune evasion, while continued expression of other elements of the same transporter may preserve essential metabolic functions and confer alternative substrate specificity. These features could be critical in mycoplasmas, where limitations in both transcriptional regulators and transport systems may prevail. This study also documents that P63 contains an uncharacteristic hydrophobic sequence between predicted nucleotide binding motifs and displays an amphiphilic character in detergent fractionation. Both features are consistent with an evolutionary adaptation favoring integral association of this putative energy-transducing component with the single mycoplasma membrane.

Antigenic topology of the P29 surface lipoprotein of Mycoplasma fermentans: differential display of epitopes results in high-frequency phase variation

Antibodies to P29, a major lipid-modified surface protein of Mycoplasma fermentans, reveal phase variation of surface epitopes occurring with high frequency in clonal lineages of the organism. This occurs despite continuous expression of the entire epitope-bearing P29 product (detected by Western immunoblotting) and contrasts with phase variation of other surface antigens mediated by differential expression of proteins. To understand the structure and antigenic topology of P29, the single-copy p29 gene from strain PG18 was cloned and sequenced. The gene encodes a prolipoprotein containing a signal sequence predicted to be modified with lipid and cleaved at the N-terminal Cys-1 residue of the mature P29 lipoprotein. The remaining 218-residue hydrophilic sequence of P29 is predicted to be located external to the single plasma membrane. Additional Cys residues at positions 91 and 128 in the mature protein were shown to form a 36-residue disulfide loop by selectively labeling sulfhydryl groups that were liberated only after chemical reduction of monomeric P29. Two nearly identical charged amino acid sequences occurred in P29, within the disulfide loop and upstream of this structure. Two distinct epitopes binding different monoclonal antibodies were associated with opposite ends of the P29 protein, by mapping products expressed in Escherichia coli from PCR-generated 3' deletion mutations of the p29 gene. Each monoclonal antibody detected high-frequency and noncoordinate changes in accessibility of the corresponding epitopes in colony immunoblots of clonal variants, yet sequencing of the p29 gene from these variants and analysis of disulfide bonds revealed no associated changes in the primary sequence or disulfide loop structure of P29. These results suggest that P29 surface epitope variation may involve masking of selected regions of P29, possibly by other surface components undergoing phase variation by differential expression. Differential masking may be an important mechanism for altering the antigenic or functional surface topology of this mycoplasma and other wall-less mycoplasmas.

Vision and cognition in the natural philosophy of Albert the Great (Albertus Magnus)

Albert the Great (Albertus Magnus, ca. 1197-1280) descended from a nobleman's family in Upper Suebia and studied natural philosophy and theology at the University of Padova, where he joined the Dominican order. Confronted with Aristotelian thought mainly in its Arabic modification (Avicenna, Al-Farabi, Averroes, Alhazen, Costa ben Luca and others) from his days in Padova, he elaborated in several books on the principles of natural philosophy, biology, brain and sense functions and psychology in addition to his theological and exegetic works. His observations and concepts on vision are discussed in detail. It is pointed out that Albert discovered some phenomena of vision not before known such as vestibular nystagmus and rod monochromacy, i.e. total colour blindness accompanied by photophobia. Based on clinical observations Albert also postulated a decussation of the optic nerve fibres at the optic chiasm. Albert's concept of higher order cognitive function is discussed and some of his explanations of dreams and neuropsychiatric disease on the basis of his cognitive model are mentioned. Albert's thoughts on vision and other sense perceptions, higher brain functions and cognition are considered as progressive elaborations of Galenic concepts as adapted by some Patristic theologians and the Arabic natural scientists and philosophers of the 9th-11th century.

AMT catalepsy and hypokinesia: interaction with morphine and cocaine

Acute morphine induced a dose-dependent hypokinesia and rigidity, but only mild and non-dose-dependent catalepsy. AMT, injected 1/2 h after morphine, slightly potentiated catalepsy but not hypokinesia during 3 h after morphine; in contrast, rigidity was decreased. The behavioral changes induced by AMT were accelerated in onset and reached their usual development, although AMT toxicity and hypothermia were completely antagonized; thus, it would appear that AMT hypokinesia/catalepsy are not the consequence of toxicity. When morphine was injected 4 h after AMT, a mutual potentiation of the two drugs on hypokinesia and catalepsy was observed, although previous biochemical measurements had shown no effect of morphine on CA depletion under these conditions. Rigidity appeared to be antagonized. After 17 days of repeated injections, morphine no longer elicited hypokinesia and catalepsy, but no cross-tolerance developed to the AMT behavioral changes. A similar lack of cross-tolerance to the effects of AMT or haloperidol was observed when morphine tolerance was induced by pellet implantation. Catalepsy and hypokinesia developed in a much more pronounced way after two large i.p. doses than after small, multiple administration of AMT; this difference was accompanied by a significantly lower concentration of brain DA, but not NA in the former group. The hyperthermic response observed after a 40 mg/kg s.c. injection of morphine was reversed to hypothermia when the same dose was given 4 or 10 h after CA synthesis inhibition. Cocaine strongly antagonized AMT hypokinesia and catalepsy when given 8 1/2 h after AMT, and, although to a lesser extent, even when injected 12 1/2 h after AMT.

Effects of morphine on the turnover of brain catecholamines and serotonin in rats-acute morphine administration

Morphine increased the rate of brain dopamine (DA) depletion when given before alpha-methyl-p-tyrosine (AMT) or alpha-propyl-dopacetamide, but not when given after AMT. No effect of morphine was found on the rate of depletion of brain noradrenaline (NA) or serotonin (5-HT) after the two synthesis inhibitors. The accumulation of homovanillic acid and 5-hydroxy-indoleacetic acid induced by probenecid was significantly increased by morphine pretreatment, whereas the accumulation of 3-methoxy-4-hydroxy-phenylglycol sulphate was not changed. These findings can be best explained by the hypothesis that morphine increases the non-functional intraneuronal catabolism of newly synthesized DA and 5-HT, without much effect on the monoamines already taken up in the synaptic vesicles. NA turnover does not seem to be changed by acute morphine administration.

Effects of morphine on the turnover of brain catecholamines and serotonin in rats-chronic morphine administration

The turnover of brain monoamine was studied in rats in which different degrees of tolerance to and dependence on morphine were induced by pellet implantation. The degree of tolerance to morphine was assessed by measuring the increase in effective dose for an antinociceptive effect (vocalization test). The rate of depletion of brain dopamine (DA) and serotonin (5-ht) after alpha-methyl-p-tyrosine (AMT) or alpha-propyl-dopacetamide (dopacetamide) was not changed by chronic morphine treatment. In contrast, the accumulation of brain homovanillic acid HVA) and 5-hydroxyindoleacetic acid (5-HIAA) after probenecid was significantly increased, but there was no correlation between the biochemical changes and the degree of tolerance/dependence of the animals; at a very high degree of dependence 5-HIAA accumulation even became normal. In rats in which smaller amounts of morphine were repeatedly injected every 8 hr for 1 week the increased accumulation of HVA and 5-HIAA persisted in spite of complete tolerance to the antinociceptive effect. The rate of depletion of brain noradrenaline (NA) after AMT or dopacetamide was not changed and the accumulation of brain 3-methoxy-4-hydroxy-phenylglycol sulphate (MHPG-SO4) after probenecid was not affected in most chronic morphine groups. In the group with the highest degree of tolerance/dependence NA depletion after AMT was even retarded. The results suggest that chronic morphine treatment increases the synthesis and the intraneuronal destruction of newly synthesized DA and 5-HT without changing the rate of functional utilization of the monoamines. It is unlikely that the changes in monoamine metabolism are causally related to processes leading to morphine tolerance/dependence.

The effect of yohimbine on the turnover of brain catecholamines and serotonin

Yohimbine moderately increased the depletion of brain dopamine (DA) after alpha-methyl-p-tyrosine (AMT) only when the two drugs were given at the same time; the baseline concentration of brain homovanillic acid (HVA) and its accumulation after probenecid were strongly increased by yohimbine. Yohimbine markedly decreased the concentration of brain noradrenaline (NA), both when given alone and before or at the same time as AMT; when it was given at an increasing interval after AMT, the effect became progressively smaller. The baseline concentration of brain 3-methyoxy-4-hydroxyphenylethyleneglycol sulphate and its accumulation after probenecid were increased by yohimbine; this effect was not as marked as that on HVA and was proportional to the quantity of NA depleted in the Amt method. The accumulation of brain k-hydroxyindoleacetic acid after probenecid was decreased by yohimbine pretreatment.