Arteriovenous Fistula Maturation in Patients with Ipsilateral Versus Contralateral Tunneled Dialysis Catheter: A Systematic Review and Meta-analysis

BACKGROUND

Although it is evident that a prior history of tunneled dialysis catheter (TDC) affects arteriovenous fistula (AVF) function, it is unclear whether its location (contralateral versus ipsilateral to AVF) has any effect on AVF maturation and failure rates. We aimed to document this possible effect.

METHODS

This systematic review and meta-analysis were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies comparing outcomes between patients with contralateral TDC (CONTRA group) and those with ipsilateral one (IPSI group) were examined for inclusion. A random effects model meta-analysis of the odds ratio (OR) was conducted. Primary outcomes were AVF functional maturation, assisted maturation, and failure rates.

RESULTS

Four eligible studies comprising 763 patients were included in the meta-analysis. There were no significant differences in terms of AVF functional maturation (OR: 1.49; 95% confidence interval [CI]: 0.64-3.47; I2 = 83.4%), assisted maturation (OR: 0.59; 95% CI: 0.29-1.19; I2 = 61.4%), and failure rates (OR: 0.67; 95% CI: 0.29-1.58; I2 = 83.3%) between the 2 study groups.

CONCLUSIONS

TDC laterality seems not to affect fistula maturation rate in patients requiring TDC placement and concurrent AVF creation, but rather, vein- and patient-related characteristics might play a more important role in choosing TDC access site. Further studies are needed to validate these results.

Specific configurations of electrical synapses filter sensory information to drive choices in behavior

Synaptic configurations in precisely wired circuits underpin how sensory information is processed by the nervous system, and the emerging animal behavior. This is best understood for chemical synapses, but far less is known about how electrical synaptic configurations modulate, in vivo and in specific neurons, sensory information processing and context-specific behaviors. We discovered that INX-1, a gap junction protein that forms electrical synapses, is required to deploy context-specific behavioral strategies during C. elegans thermotaxis behavior. INX-1 couples two bilaterally symmetric interneurons, and this configuration is required for the integration of sensory information during migration of animals across temperature gradients. In inx-1 mutants, uncoupled interneurons display increased excitability and responses to subthreshold temperature stimuli, resulting in abnormally longer run durations and context-irrelevant tracking of isotherms. Our study uncovers a conserved configuration of electrical synapses that, by increasing neuronal capacitance, enables differential processing of sensory information and the deployment of context-specific behavioral strategies.

Acute thrombosis of a giant perimedullary arteriovenous fistula in a pediatric HHT patient

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant hereditary disorder that results in arteriovenous malformations (AVMs) in the nose, mucocutaneous surfaces and visceral organs, including lung, brain, liver, bowel and rarely spinal cord. We describe a case of a young child with HHT who presented with acute paraparesis due to acute thrombosis of a spinal perimedullary arteriovenous fistula. Patient underwent coil embolization of spinal arteriovenous shunt with resolution of clinical symptoms. This case highlights the possibility of catastrophic complications in young children with HHT, the potential preventive role of screening for spinal AVMs in HHT and the importance of timely intervention.

Vertebral Arteriovenous Fistula: A Review Article

OBJECTIVE

Vertebrovertebral fistulas (VVFs) are uncommon lesions that can arise spontaneously or secondarily to iatrogenic or mechanical trauma. We performed a systematic review of the literature to obtain information regarding demographics, clinical presentation, treatment modalities, outcome, and complications associated with treatment.

METHODS

A literature search was performed by a reference librarian and after screening, 128 case reports and 16 case series were left for inclusion in the review. All possible data were abstracted by 3 authors, results were tabulated, and descriptive statistics (mean, range, and proportions) were reported. No formal statistical analysis was performed as part of this study.

RESULTS

A total of 280 patients were analyzed. VVFs can be categorized in 3 subgroups (iatrogenic, spontaneous, and traumatic), based on the mechanism of formation, and these different causes share different underlying demographics that bear important treatment considerations. Traumatic VVFs are more commonly seen in young men; the spontaneous form is more commonly seen in young women. Iatrogenic VVFs are more commonly seen in elderly people. Spontaneous VVFs are most commonly located between C1 and C2. Most iatrogenic (n = 39; 57%), spontaneous (n = 106; 82%), and traumatic (n = 53; 73%) VVFs were treated with deconstructive (defined as occlusion of fistula and feeding vessels) endovascular therapy. Overall treatment-related permanent morbidity was 3.3% (9/270) and mortality was 1.5% (4/270).

CONCLUSIONS

VVFs are uncommon lesions, and treatment is often indicated, even in patients without retrograde venous drainage. When treatment is undertaken, the cause of presentation and associated patient demographics should be considered when planning the treatment strategy.

Integration of Plasticity Mechanisms within a Single Sensory Neuron of C. elegans Actuates a Memory

Neural plasticity, the ability of neurons to change their properties in response to experiences, underpins the nervous system's capacity to form memories and actuate behaviors. How different plasticity mechanisms act together in vivo and at a cellular level to transform sensory information into behavior is not well understood. We show that in Caenorhabditis elegans two plasticity mechanisms-sensory adaptation and presynaptic plasticity-act within a single cell to encode thermosensory information and actuate a temperature preference memory. Sensory adaptation adjusts the temperature range of the sensory neuron (called AFD) to optimize detection of temperature fluctuations associated with migration. Presynaptic plasticity in AFD is regulated by the conserved kinase nPKCε and transforms thermosensory information into a behavioral preference. Bypassing AFD presynaptic plasticity predictably changes learned behavioral preferences without affecting sensory responses. Our findings indicate that two distinct neuroplasticity mechanisms function together through a single-cell logic system to enact thermotactic behavior. VIDEO ABSTRACT.