Autonomic nervous system disorder

Also known as autonomic nervous instability. This is a general term for cases in which the function of the autonomic nervous system is impaired for various reasons, resulting in the appearance of various symptoms. The autonomic nervous system is regulated by the balance of two antagonistic nervous systems, the sympathetic nervous system and the parasympathetic nervous system, and works in cooperation with the endocrine system to automatically maintain the metabolism and functions of the entire body. When this system is impaired, a wide variety of symptoms are seen, which can be divided into those that show increased tension, such as sympathetic nervous tension or parasympathetic nervous tension, and conversely, those that show decreased tension in each autonomic nerve. In general, this does not refer to an abnormality in the autonomic nervous system itself, but rather to vague complaints such as fatigue, heart palpitations, and heavy stomach, or even those with no clear abnormalities. However, these are psychological in origin and are often mild depression or neurosis, and are different from the original autonomic nervous system imbalance. Diseases that primarily involve degeneration of the nervous system, such as Parkinson's disease, spinocerebellar degeneration, and polyneuropathy, show symptoms such as anhidrosis, inability to regulate body temperature, loss of libido, orthostatic hypotension, incontinence, and fainting attacks. In addition, Raynaud's disease and vasculogenic (Quincke) edema may show circulatory disorders due to localized autonomic nervous system abnormalities. Diabetes and various neurological disorders caused by metabolic disorders often show autonomic nervous system imbalance, including systemic symptoms such as high and low blood pressure. In rare cases, Shy-Drager syndrome, which severely affects only the autonomic nervous system, shows major symptoms such as orthostatic hypotension, fainting, constipation, diarrhea, and anhidrosis, and amyloid neuropathy and other polyneuropathies also show similar symptoms.

On the other hand, continued mental stress can lead to stomach ulcers or vomiting blood, and when these mental stress disorders cause dysfunction in various organs, they are called psychosomatic disorders. Since autonomic nervous system disorders are also strongly influenced by psychological factors, treatment at a psychiatric or psychosomatic clinic may be effective, and tranquilizers are also effective, but there are no particularly effective drugs or treatments for autonomic nervous system disorders caused by organic diseases, and they are often ineffective.

[Eijiro Satoyoshi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

自律神経不安定症ともいう。自律神経の働きが種々の原因によって障害され、いろいろの症状が現れてくる場合を総称してよばれる。自律神経は交感神経系と副交感神経系の二つの拮抗(きっこう)する神経系のバランスによって調節されており、内分泌系と協調して全身の代謝や機能保持を自動的に行っている。これが障害されると多種多様の症状がみられるが、交感神経緊張症や副交感神経緊張症など緊張亢進(こうしん)を示すものと、逆に緊張低下をそれぞれの自律神経が示す場合に分けられる。一般には本来の自律神経系の異常ではなく、体がだるいとか、心臓がどきどきするとか、胃が重いなど不定の訴え（不定愁訴(しゅうそ)）をもっているか、はっきりした異常を認めないものまで含めてよんでいるが、これらは心因によるもので、軽いうつ病ないし神経症であることが多く、本来の自律神経失調症とは異なるものである。神経系の変性を主とする病気、たとえばパーキンソン病、脊髄(せきずい)小脳変性症、多発性神経炎などでは無汗症、体温調節不能、性欲減退、起立性低血圧、失禁、失神発作などの症状がみられる。また、レイノー病や血管性（クインケ）浮腫(ふしゅ)など局所性の自律神経異常による循環障害を示す場合もある。糖尿病や種々の代謝異常による神経疾患では、高血圧や低血圧など全身症状を含めて自律神経失調症を示すことが多い。まれには、自律神経系のみを強く冒すシャイ・ドレーガー症候群Shy-Drager syndromeなどでは起立性低血圧、失神、便秘、下痢、無汗症などが主症状であり、アミロイド神経炎や他の多発神経炎でも同様な症状を呈する。

　一方、種々の精神緊張が持続すると胃潰瘍(かいよう)になったり、吐血したりするが、これらの精神緊張の異常により、種々の臓器の機能障害を示してくるものを心身症などとよんでいる。自律神経系の異常は心因によっても強い影響を受けるので、精神科ないし心療内科での加療も有効な場合があり、精神安定剤（トランキライザー）も有効であるが、器質性の病気によって生じた自律神経失調症には、あまり有効な薬剤や治療法はなく、効果をあげられない場合が少なくない。

［里吉営二郎］

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