spinal shock

(redirected from Arreflexia)

shock

 [shok]
1. a sudden disturbance of mental equilibrium.
2. a condition of acute peripheral circulatory failure due to derangement of circulatory control or loss of circulating fluid. It is marked by hypotension and coldness of the skin, and often by tachycardia and anxiety. Untreated shock can be fatal. Called also circulatory collapse.

Mechanisms of Circulatory Shock. The essentials of shock are easier to understand if the circulatory system is thought of as a four-part mechanical device made up of a pump (the heart), a complex system of flexible tubes (the blood vessels), a circulating fluid (the blood), and a fine regulating system or “computer” (the nervous system) designed to control fluid flow and pressure. The diameter of the blood vessels is controlled by impulses from the nervous system which cause the muscular walls to contract. The nervous system also affects the rapidity and strength of the heartbeat, and thereby the blood pressure as well.



Shock, which is associated with a dangerously low blood pressure, can be produced by factors that attack the strength of the heart as a pump, decrease the volume of the blood in the system, or permit the blood vessels to increase in diameter.
Types of Circulatory Shock. There are five main types: Hypovolemic (low-volume) shock occurs whenever there is insufficient blood to fill the circulatory system. Neurogenic shock is due to disorders of the nervous system. Anaphylactic (allergic) shock and septic shock are both due to reactions that impair the muscular functioning of the blood vessels. And cardiogenic shock is caused by impaired function of the heart.
Hypovolemic (Low-Volume) Shock. This is a common type that happens when blood or plasma is lost in such quantities that the remaining blood cannot fill the circulatory system despite constriction of the blood vessels. The blood loss may be external, as when a vessel is severed by an injury, or the blood may be “lost” into spaces inside the body where it is no longer accessible to the circulatory system, as in severe gastrointestinal bleeding from ulcers, fractures of large bones with hemorrhage into surrounding tissues, or major burns that attract large quantities of blood fluids to the burn site outside blood vessels and capillaries. The treatment of hypovolemic shock requires replacement of the lost volume.
Neurogenic Shock. This type, often accompanied by fainting, may be brought on by severe pain, fright, unpleasant sights, or other strong stimuli that overwhelm the usual regulatory capacity of the nervous system. The diameter of the blood vessels increases, the heart slows, and the blood pressure falls to the point where the supply of oxygen carried by the blood to the brain is insufficient, which can bring on fainting. Placing the head lower than the body is usually sufficient to relieve this form of shock.
Anaphylactic (Allergic) Shock. This type (see also anaphylaxis) is a rare phenomenon that occurs when a person receives an injection of a foreign protein but is highly sensitive to it. The blood vessels and other tissues are affected directly by the allergic reaction. Within a few minutes, the blood pressure falls and severe dyspnea develops. The sudden deaths that in rare cases follow bee stings or injection of certain medicines are due to anaphylactic reactions.
Septic Shock. This type, resulting from bacterial infection, is being recognized with increasing frequency. Certain organisms contain a toxin that seems to act on the blood vessels when it is released into the bloodstream. The blood eventually pools within parts of the circulatory system that expand easily, causing the blood pressure to drop sharply. Gram-negative shock is a form of septic shock due to infection with gram-negative bacteria.
Cardiogenic Shock. This type may be caused by conditions that interfere with the function of the heart as a pump, such as severe myocardial infarction, severe heart failure, and certain disorders of rate and rhythm.
Pathogenesis of shock. (ARDS = adult respiratory distress syndrome, GI = gastrointestinal, IL = interleukin, TNF = tumor necrosis factor.) From Damjanov, 2000.
anaphylactic shock see anaphylactic shock.
cardiogenic shock shock resulting from primary failure of the heart in its pumping function, as in myocardial infarction, severe cardiomyopathy, or mechanical obstruction or compression of the heart; clinical characteristics are similar to those of hypovolemic shock.
colloidoclastic shock colloidoclasia.
cultural shock feelings of helplessness and discomfort experienced by an outsider attempting to comprehend or effectively adapt to a different cultural group or unfamiliar cultural context.
electric shock see electric shock.
hypovolemic shock shock resulting from insufficient blood volume for the maintenance of adequate cardiac output, blood pressure, and tissue perfusion. Without modification the term refers to absolute hypovolemic shock caused by acute hemorrhage or excessive fluid loss. Relative hypovolemic shock refers to a situation in which the blood volume is normal but insufficient because of widespread vasodilation as in neurogenic shock or septic shock. Clinical characteristics include hypotension; hyperventilation; cold, clammy, cyanotic skin; a weak and rapid pulse; oliguria; and mental confusion, combativeness, or anxiety.
insulin shock a hypoglycemic reaction to overdosage of insulin, a skipped meal, or strenuous exercise in an insulin-dependent diabetic, with tremor, dizziness, cool moist skin, hunger, and tachycardia; if untreated it may progress to coma and convulsions.
respirator shock circulatory shock due to interference with the flow of blood through the great vessels and chambers of the heart, causing pooling of blood in the veins and the abdominal organs and a resultant vascular collapse. The condition sometimes occurs as a result of increased intrathoracic pressure in patients who are being maintained on a mechanical ventilator.
septic shock shock associated with overwhelming infection, usually by gram-negative bacteria, although it may be produced by other bacteria, viruses, fungi, and protozoa. It is thought to result from the action of endotoxins or other products of the infectious agent on the vascular system causing large volumes of blood to be sequestered in the capillaries and veins; activation of the complement and kinin systems and the release of histamine, cytokines, prostaglandins, and other mediators may be involved. Clinical characteristics include initial chills and fever, warm flushed skin, increased cardiac output, and a lesser degree of hypotension than with hypovolemic shock; if therapy is ineffective, it may progress to the clinical picture associated with hypovolemic shock.
shell shock old term for posttraumatic stress disorder.
spinal shock the loss of spinal reflexes after injury of the spinal cord that appears in the muscles innervated by the cord segments situated below the site of the lesion.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

spi·nal shock

transient depression or abolition of reflex activity below the level of an acute spinal cord injury or transection.
Farlex Partner Medical Dictionary © Farlex 2012

spinal shock

Critical care Neurogenic shock A clinical complex caused by trauma to the vertebral column and spinal cord, resulting in a transient–3-6 wk in duration–loss of reflex activity due to functional or anatomic interruption of the corticospinal tracts; SS is seen immediately after complete injury at the T6 level or above, and is accompanied by arreflexia, loss of sensation, flaccid paralysis below the level of the lesion, flaccid bladder with urine retention, and lax anal sphincter Obstetrics An idiopathic postpartum vasomotor collapse that follows spinal anesthesia, 2º to various stressants of delivery–eg, acute blood loss, electrolytic imbalance, adrenocortical insufficiency, pre-eclampsia, anesthetics, amniotic fluid embolism.
Spinal shock
Arreflexia–complete 'failure' below lesion–eg, tetraplegia, paraplegia, overflow incontinence, paralytic ileus, gastric atony and depression of cremasteric reflex; arreflexia is followed several wks later by
Hyperreflexia–exaggeration of reflexes with flexor spasms and autonomic dysreflexia, bladder distention, diaphoresis, HTN, and bradycardia; certain reflexes–eg, anal 'wink', bulbocavernosus and cremasteric reflexes, full penile erection, reflex leg withdrawal and Babinski sign, are retained after complete spinal cord transection since these reflexes don't require higher levels of control
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

spi·nal shock

(spīnăl shok)
Transient depression of reflex activity below level of an acute spinal cord injury or transection.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
This finding made the neuropathy part of the syndrome with the denomination of cerebellar ataxia, neuropathy, and vestibular arreflexia syndrome (CANVAS).
(4) Caracteriza-se pela fraqueza bilateral e simetrica dos membros, e manifesta-se com tetraparesia flacida com hiporreflexia ou arreflexia. Esta associada a fraqueza muscular respiratoria, podendo resultar em insuficiencia respiratoria aguda (IRpA), dificuldade no desmame da ventilacao mecanica invasiva (VM) e aumento do tempo de internacao hospitalar.
Sendo exemplos de deficit ou perda funcional: a paralisia, a hipoestesia, a anestesia, a arreflexia, o declinio da inteligencia ou da memoria; e de liberacao ou exacerbacao: hipertonia, hiperreflexia, movimentos anormais, disestesia; por fim exemplos de efeito irritativo: dor por irritacao de nervo periferico, crise epileptica.
Observou-se em nosso estudo que tres individuos (25%) apresentaram sequelas do virus da poliomielite (paralisia infantil) que causa alteracoes no sistema nervoso (SN), como a destruicao de neuronios motores, principalmente nos musculos inferiores de forma assimetrica, tendo como principais caracteristicas a flacidez muscular, com sensibilidade conservada e arreflexia no segmento atingido (Araujo, 2005; Costa, 2001).
No obstante, se sabe que el SGB constituye un conjunto de sindromes que se manifiestan como diferentes subtipos de trastornos (sindrome de Miller Fisher; debilidad faringo-cervico-braquial, diplejia facial con parestesias distales, ataxia grave con trastornos sensitivos y pandisautonomia aguda), con rasgos electrofisiologicos y anatomopatologicos distintos; de este modo, es preferible definir el SGB como una polirradiculoneuropatia autoinmune, caracterizada clinicamente por la presencia de una paralisis flacida con arreflexia, trastorno sensorial variable y elevacion de las proteinas en el liquido cefalorraquideo (LCR) (3, 6).
Foi reduzida a frequencia de hiperreflexia, sendo esta unilateral nos dois casos apresentados, e nenhuma hiporreflexia ou arreflexia foi encontrada.