Functional brainstem changes in response to bladder function alteration elicited by surgical reduction in bladder capacity: a functional magnetic resonance imaging study

Use of viruses for interrogating viscera-specific projections in central nervous system

Each internal organ may perform many different functions under central regulation, yet how these processes are coordinated is poorly understood. The last three decades have witnessed a renaissance in tract tracing with genetically engineered strains of viruses that rapidly interrogate viscera-specific projections in the CNS. The application of novel methods to study cell type-specific projections through trans-synaptically transmitted virus 'label' highlights projections exclusively originating from neurons expressing a very specific molecular phenotype. This has opened the door to neuroanatomical studies interrogating organ-specific projections in the CNS at an unprecedented scale. In this contribution to the Special Issue we present an overview of the present state and of future opportunities in charting viscera-brain specific connectivity and in linking brain circuits to internal organ function.

Changes in attention variables in those who treated with anticholinergic agents for nonmonosymptomatic enuresis

Purpose

Brain dysfunction related to areas regarding attention and arousal may occur not only in patients with attention-deficit/hyperactivity disorder (ADHD) but also in patients with enuresis and daytime symptoms. This study aimed to investigate changes in computerized comprehensive attention tests (CATs), a psychometric test for ADHD when patients with nonmonosymptomatic enuresis (NME) were treated with anticholinergic agents.

Materials and Methods

Thirty patients with NME featuring overactive bladder were prospectively enrolled. They were treated with 5 mg of solifenacin to control daytime symptoms. Using CATs, patients were evaluated during 12 weeks of treatment. Four subtests of attention (visual and auditory selective attention, sustained attention, and flanker tests) were measured. For each subtest, four domains (omission error, commission error, response time [RT], and standard deviation of RT) were assessed.

Results

Only one domain of the flanker test was in the deficient range at baseline. The presence of urge incontinence affected follow-up results on the sustained attention tests. Treatment with anticholinergic agents did not significantly affect attention variables but changes in several variables were correlated with bladder symptoms and enuresis.

Conclusions

Minimal baseline defects in attention function were seen in patients with NME. Follow-up results for some attention variables were affected by daytime symptoms and enuresis. These results suggest that altered brain function in enuretic patients influences improvement in both attention and bladder function.

The Role of the Periaqueductal Gray Matter in Lower Urinary Tract Function

The periaqueductal gray matter (PAG), as one of the mostly preserved evolutionary components of the brain, is an axial structure modulating various important functions of the organism, including autonomic, behavioral, pain, and micturition control. It has a critical role in urinary bladder physiology, with respect to storage and voiding of urine. The PAG has a columnar composition and has extensive connections with its cranially and caudally located components of the central nervous system (CNS). The PAG serves as the control tower of the detrusor and sphincter contractions. It serves as a bridge between the evolutionary higher decision-making brain centers and the lower centers responsible for reflexive micturition. Glutamatergic cells are the main operational neurons in the vlPAG, responsible for the reception and relay of the signals emerging from the bladder, to related brain centers. Functional imaging studies made it possible to clarify the activity of the PAG in voiding and filling phases of micturition, and its connections with various brain centers in living humans. The PAG may be affected in a wide spectrum of disorders, including multiple sclerosis (MS), migraine, stroke, Wernicke’s encephalopathy, and idiopathic normal pressure hydrocephalus, all of which may have voiding dysfunction or incontinence, in certain stages of the disease. This emphasizes the importance of this structure for the basic understanding of voiding and storage disorders and makes it a potential candidate for diagnostic and therapeutic interventions.

Current Understanding on Pain Mechanism in Migraine and Cluster Headache

CONTEXT

Migraine and cluster headache are undoubtedly painful conditions. The respective pathogenesis of these two conditions is incompletely understood. In both cases, the treatments used have largely been empirical and have relied to a much lesser extent on our understanding of the mechanisms causing pain. We hereby review the pain mechanisms in migraine and cluster headache, two of the commonest primary headache disorders.

EVIDENCE ACQUISITION

A review of the English literature was conducted by searching PubMed for studies on pain mechanism in migraine and cluster headache. We entered [migraine] and [pain mechanism] in Pubmed and 488 articles were obtained. Articles were then included according to their relevance to the topic. Similarly, [cluster headache] and [pain mechanism] revealed 79 search results.

RESULTS

There is evidence that the trigeminovascular system and neurogenic inflammation play important roles, together with certain areas of the brain, leading to these conditions being termed 'neurovascular headaches'. Functional imaging findings suggest a possible role of the dorsolateral pons in generating migraine attacks while the role of the hypothalamus in cluster headache is more firmly established.

CONCLUSIONS

Migraine and cluster headache have complex pathophysiologies. The exact mechanism causing pain in both conditions is incompletely understood and more research needs to be undertaken in this area.

Primary Nocturnal Enuresis: A Review

Context

Nocturnal enuresis or bedwetting is the most common type of urinary incontinence in children. It has significant psychological effects on both the child and the family. Enuresis nocturna is defined as the inability to hold urine during the night in children who have completed toilet training. It is termed as being “primary” if no continence has ever been achieved or “secondary if it follows at least 6 months of dry nights. The aim of this review was to assemble the pathophysiological background and general information about nocturnal enuresis.

Evidence Acquisition

This review was performed by evaluating the literature on nocturnal enuresis published between 1970 and 2015, available via PubMed and using the keywords “nocturnal enuresis,” “incontinence,” “pediatric,” “review,” and “treatment.”

Results

Children with nocturnal enuresis produce urine at higher rates during the night, and may have lower bladder capacities. Some children with nocturnal enuresis may also have daytime urgency, frequency, and urinary incontinence. Treatment includes aggressive treatment of accompanying constipation or urinary tract infections, behavioral changes, and medical therapy. Alarm therapy remains the first-line treatment modality for primary nocturnal enuresis. High rates of patient compliance and relapse mean that alternative treatments remain on the agenda.

Conclusions

Nocturnal enuresis is a common problem that has multifaceted effects on both the child and the family. Due to multiple etiologic factors, nocturnal enuresis is still not clearly defined.

Central control of visceral pain and urinary tract function

Afferent input from Aδ and C-fibres innervating the urinary bladder are processed differently by the brain, and have different roles in signaling bladder sensation. Aδ fibres that signal bladder filling activate a spino-bulbo-spinal loop, which relays in the midbrain periaqueductal grey (PAG) and pontine micturition centre (PMC). The excitability of this circuitry is regulated by tonic GABAergic inhibitory processes. In humans and socialised animals micturition is normally under volitional control and influenced by a host of psychosocial factors. Higher nervous decision-making in a social context to 'go now' or 'do not go' probably resides in frontal cortical areas, which act as a central control switch for micturition. Exposure to psychosocial stress can have profoundly disruptive influence on the process and lead to maladaptive changes in the bladder. During sleeping the voiding reflex threshold appears to be reset to a higher level to promote urinary continence. Under physiological conditions C-fibre bladder afferents are normally silent but are activated in inflammatory bladder states and by intense distending pressure. Following prolonged stimulation visceral nociceptors sensitise, leading to a lowered threshold and heightened sensitivity. In addition, sensitization may occur within the central pain processing circuitry, which outlasts the original nociceptive insult. Visceral nociception may also be influenced by genetic and environmental influences. A period of chronic stress can produce increased sensitivity to visceral pain that lasts for months. Adverse early life events can produce even longer lasting epigenetic changes, which increase the individual's susceptibility to developing visceral pain states in adulthood.

The enigma of the dorsolateral pons as a migraine generator

In this editorial, we integrate improved understanding of functional and structural brain stem anatomy with lessons learned from other disciplines on brainstem function to provide an alternative interpretation to the data used to support the brainstem migraine generator theory.