Autonomic nervous system disorders in stroke

Disturbances of the autonomic nervous system are common in patients with various cerebrovascular diseases. They are attributed to damage of the central autonomic network, particularly in the frontoparietal cortical areas and in the brain stem, or to a disruption of the autonomic pathways descending from the hypothalamus via the mesencephalon, pons, and medulla to the spinal cord. The most common clinical problems include abnormalities in heart rate and blood pressure regulation, reflecting cardiovascular autonomic dysfunction, and asymmetric sweating with cold hemiplegic limbs, reflecting changes in the sudomotor and vasomotor regulatory systems. Bladder and bowel dysfunction and impotence are also frequent complaints after stroke, but the present knowledge concerning their prevalence and clinical significance is still limited. Cardiovascular autonomic dysfunction, which is mainly related to increased sympathetic activity, is most evident in the acute phase of stroke, whereas other autonomic disorders, such as abnormal sweating, are long-standing or even irreversible. In addition to the well-established sympathetic hyperfunction, abnormalities of the parasympathetic nervous system may also contribute to the autonomic imbalance after stroke. Reliable recognition of autonomic dysfunction using quantitative analysis methods is important, because these disturbances are not only subjectively disabling and uncomfortable, but they may also be prognostically unfavorable. Moreover, quantitative measurements also form the ground for successive treatment of various stroke-related autonomic disorders.     

Post-streptococcal autoimmune disorders of the central nervous system

Group A Streptococcus can induce autoimmune disease in humans with particular involvement of the heart, joints, and brain. The spectrum of post-streptococcal disease of the central nervous system (CNS) has been widened recently and includes movement disorders (chorea, tics, dystonia, and Parkinsonism), psychiatric disorders (particularly emotional disorders), and associated sleep disorders. Neuroimaging and pathological studies indicate that the most vulnerable brain region is the basal ganglia. The immunopathogenesis of the disease is incompletely defined, and although there is some support for autoantibody-mediated disease, several conflicting studies cast doubt on the autoantibody hypothesis. It has been speculated that post-streptococcal autoimmunity has a role in common neuropsychiatric disease but the evidence is conflicting and routine screening of patients with Tourette syndrome and obsessive-compulsive disorder for post-streptococcal autoimmune abnormalities is not be recommended at present. However, post-streptococcal disorders of the CNS remain a useful model of neuropsychiatric disease, which may improve our understanding of abnormal movements and behaviours in children.     

Post-streptococcal autoimmune disorders of the central nervous system

PURPOSE OF REVIEW: Autoimmune disease has long been intertwined with investigations of infectious causes. Antibodies that are formed against an infectious agent can, through the process of molecular mimicry, also recognize healthy cells. When this occurs, the immune system erroneously destroys the healthy cells causing autoimmune disease in addition to appropriately destroying the offending infectious agent and attenuating the infectious process. The first infectious agent shown to cause a post-infectious autoimmune disorder in the central nervous system was Streptococcus pyogenes in Sydenham's chorea. The present review summarizes the most recent published findings of central nervous system diseases that have evidence of a post-streptococcal autoimmune etiology. RECENT FINDINGS: Sydenham's chorea and other central nervous system illnesses that are hypothesized to have a post-streptococcal autoimmune etiology appear to arise from targeted dysfunction of the basal ganglia. PANDAS (pediatric autoimmune disorders associated with streptococcal infections) is the acronym applied to a subgroup of children with obsessive-compulsive disorder or tic disorders occurring in association with streptococcal infections. In addition, there are recent reports of dystonia, chorea encephalopathy, and dystonic choreoathetosis occurring as sequelae of streptococcal infection. Investigators have begun to isolate and describe antistreptococcal-antineuronal antibodies as well as possible genetic markers in patients who are susceptible to these illnesses. SUMMARY: Clinical and research findings in both immunology and neuropsychiatry have established the existence of post-streptococcal neuropsychiatric disorders and are beginning to shed light on possible pathobiologic processes.     

Abnormal glycosphingolipid metabolism in the nervous system of galactosialidosis

In an autopsy case of galactosialidosis, GM3, GM2, GM1, and GD1a were accumulated in sympathetic and spinal ganglia and grey matter of the spinal cord. Especially, the accumulations of GM3 and GM2 amounted to 41- and 86-fold increases in sympathetic ganglia, respectively, as compared to normal controls. In addition LacCer, GA2 and GA1 were accumulated in sympathetic and spinal ganglia. The accumulations of GM3 and GD1a are considered to be the result of defective lysosomal sialidase activity and the accumulation of GM1, LacCer and GA1 is also considered to be due to decreased beta-galactosidase activity in this disorder. To better understand the possible mechanism of GM2 accumulation, we determined the activity of GM2 synthesizing enzyme (GM3:UDP-GalNAc transferase), as well as hexosaminidase activity, in sympathetic ganglia, but they did not change. Abnormal ganglioside and neutral glycosphingolipid metabolism, as well as sialyloligosaccharide and sialylglycoprotein metabolism, may be involved in the pathogenesis of this disorder.     

Paroxysmal disorders and the autonomic nervous system in pediatrics

The autonomic nervous system (ANS) plays a complex and vital role in involuntary homeostasis of bodily function. This paper discusses the function and dysfunction of the ANS in common pediatric paroxysmal disorders including epilepsy, breath-holding spells, and syncope.     

Chemokines and central nervous system disorders

Chemokines and their receptors are large families of inflammatory molecules responsible for a number of biologic functions including the accumulation of leukocytes at tissue sites. Over the past 8 years, a number of studies have indicated a role for chemokines in the pathogenesis of CNS inflammatory diseases. This minireview provides a brief summary of our current knowledge of chemokines and CNS inflammatory diseases including experimental autoimmune encephalomyelitis, multiple sclerosis, virus-induced demyelinating diseases, Alzheimer's disease, and central nervous system bacterial-induced diseases.     

Noninfectious central nervous system inflammatory disorders

Acute central nervous system (CNS) inflammation may occur as a monophasic illness or may represent the first attack of a chronic inflammatory disorder, such as multiple sclerosis, neuromyelitis optica, or CNS vasculitis. We review essential components of the initial assessment, diagnostic workup, acute and chronic management strategies, and research issues pertaining to children with CNS inflammatory diseases and suggest methods for these competencies to be attained during the course of child neurology residency training.     

Role of MRI in the pediatric central nervous system disorders

Recent rapid development of the MRI system has enabled us to diagnose precisely the disorders of the central nervous system (CNS) also in neonates and young children. Because of a long studying time, the use of oral chloral hydrate or other alternative drugs for sedation, such as secobarbital and meperidine, is necessary for young children under 6 years of age. The advantages of MRI are the optional plane imaging, a high contrast resolution, and the artifact-free imaging from the surrounding bones and air. MRI can detect myelination disorders and the lesions in the posterior fossa, the middle fossa, and the spinal canal. These abnormalities are difficult to depict with conventional X-ray CT scanning. MRI is useful also for the survey of various congenital anomalies of the brain and the spine. Furthermore, it is sensitive enough to detect the CNS blood flow and the cerebrospinal fluid (CSF) flow. Arteriovenous malformation, moyamoya disease, and sinus thrombosis are diagnosed by MRI without using contrast media, CSF flow void phenomena in the aqueduct and the Monro's foramina are indexes of the CSF pathway obstruction and of normal pressure hydrocephalus.     

Central nervous system manifestations of mitochondrial disorders

The central nervous system (CNS) is, after the peripheral nervous system, the second most frequently affected organ in mitochondrial disorders (MCDs). CNS involvement in MCDs is clinically heterogeneous, manifesting as epilepsy, stroke-like episodes, migraine, ataxia, spasticity, extrapyramidal abnormalities, bulbar dysfunction, psychiatric abnormalities, neuropsychological deficits, or hypophysial abnormalities. CNS involvement is found in syndromic and non-syndromic MCDs. Syndromic MCDs with CNS involvement include mitochondrial encephalomyopathy, lactacidosis, stroke-like episodes syndrome, myoclonic epilepsy and ragged red fibers syndrome, mitochondrial neuro-gastrointestinal encephalomyopathy syndrome, neurogenic muscle weakness, ataxia, and retinitis pigmentosa syndrome, mitochondrial depletion syndrome, Kearns-Sayre syndrome, and Leigh syndrome, Leber's hereditary optic neuropathy, Friedreich's ataxia, and multiple systemic lipomatosis. As CNS involvement is often subclinical, the CNS including the spinal cord should be investigated even in the absence of overt clinical CNS manifestations. CNS investigations comprise the history, clinical neurological examination, neuropsychological tests, electroencephalogram, cerebral computed tomography scan, and magnetic resonance imaging. A spinal tap is indicated if there is episodic or permanent impaired consciousness or in case of cognitive decline. More sophisticated methods are required if the CNS is solely affected. Treatment of CNS manifestations in MCDs is symptomatic and focused on epilepsy, headache, lactacidosis, impaired consciousness, confusion, spasticity, extrapyramidal abnormalities, or depression. Valproate, carbamazepine, corticosteroids, acetyl salicylic acid, local and volatile anesthetics should be applied with caution. Avoiding certain drugs is often more beneficial than application of established, apparently indicated drugs.     

Genetics of central nervous system developmental disorders

The construction of the nervous system is regulated by genetic and environmental factors. In this article, we have highlighted some of the important molecules and genes that contribute to early stages of CNS development. Future research in the neurosciences will address how genetic and environmental factors interact with each other during brain development and in the mature nervous system.     

Reductive metabolism of ascorbic acid in the central nervous system

Rat and feline brain and feline spinal cord were examined for the presence of semidehydroascorbate reductase (EC 1.6.5.4) and dehydroascorbate reductase (EC 1.8.5.1). Semidehydroascorbate reductase (SDAR), as monitored by both ascorbyl radical-dependent nicotinamide adenine dinucleotide (NADH) oxidase activity and NADH-dependent ascorbyl radical quenching, was present in all tissues studied. Rat cerebrum exhibited the highest levels and feline spinal cord the lowest. SDAR activity was about twice as high in feline cerebral cortex as in underlying white matter, and paralleled ascorbic acid levels. Subcellular fractionation of rat cerebrum localized most SDAR in a large granular fraction. In contrast, dehydroascorbate reductase was not detectable in any of the tissues examined. The results suggest that semidehydroascorbate reductase is the major enzyme catalyzing the regeneration of reduced ascorbic acid in the central nervous system.