Spinal Cord: A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.Anesthesia, General: Procedure in which patients are induced into an unconscious state through use of various medications so that they do not feel pain during surgery.Anesthesia: A state characterized by loss of feeling or sensation. This depression of nerve function is usually the result of pharmacologic action and is induced to allow performance of surgery or other painful procedures.Anesthesia, Spinal: Procedure in which an anesthetic is injected directly into the spinal cord.Anesthesia, Local: A blocking of nerve conduction to a specific area by an injection of an anesthetic agent.Spinal Cord Injuries: Penetrating and non-penetrating injuries to the spinal cord resulting from traumatic external forces (e.g., WOUNDS, GUNSHOT; WHIPLASH INJURIES; etc.).Anesthesia, Epidural: Procedure in which an anesthetic is injected into the epidural space.Anesthesia, Inhalation: Anesthesia caused by the breathing of anesthetic gases or vapors or by insufflating anesthetic gases or vapors into the respiratory tract.Anesthesia, Conduction: Injection of an anesthetic into the nerves to inhibit nerve transmission in a specific part of the body.Anesthesia, Intravenous: Process of administering an anesthetic through injection directly into the bloodstream.Anesthesia, Obstetrical: A variety of anesthetic methods such as EPIDURAL ANESTHESIA used to control the pain of childbirth.Anesthesia Recovery Period: The period of emergence from general anesthesia, where different elements of consciousness return at different rates.Anesthesia, Dental: A range of methods used to reduce pain and anxiety during dental procedures.Injections, Spinal: Introduction of therapeutic agents into the spinal region using a needle and syringe.Anesthetics, Inhalation: Gases or volatile liquids that vary in the rate at which they induce anesthesia; potency; the degree of circulation, respiratory, or neuromuscular depression they produce; and analgesic effects. Inhalation anesthetics have advantages over intravenous agents in that the depth of anesthesia can be changed rapidly by altering the inhaled concentration. Because of their rapid elimination, any postoperative respiratory depression is of relatively short duration. (From AMA Drug Evaluations Annual, 1994, p173)Anesthetics, Intravenous: Ultrashort-acting anesthetics that are used for induction. Loss of consciousness is rapid and induction is pleasant, but there is no muscle relaxation and reflexes frequently are not reduced adequately. Repeated administration results in accumulation and prolongs the recovery time. Since these agents have little if any analgesic activity, they are seldom used alone except in brief minor procedures. (From AMA Drug Evaluations Annual, 1994, p174)Adjuvants, Anesthesia: Agents that are administered in association with anesthetics to increase effectiveness, improve delivery, or decrease required dosage.Propofol: An intravenous anesthetic agent which has the advantage of a very rapid onset after infusion or bolus injection plus a very short recovery period of a couple of minutes. (From Smith and Reynard, Textbook of Pharmacology, 1992, 1st ed, p206). Propofol has been used as ANTICONVULSANTS and ANTIEMETICS.Anesthetics, Local: Drugs that block nerve conduction when applied locally to nerve tissue in appropriate concentrations. They act on any part of the nervous system and on every type of nerve fiber. In contact with a nerve trunk, these anesthetics can cause both sensory and motor paralysis in the innervated area. Their action is completely reversible. (From Gilman AG, et. al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed) Nearly all local anesthetics act by reducing the tendency of voltage-dependent sodium channels to activate.Spinal Nerves: The 31 paired peripheral nerves formed by the union of the dorsal and ventral spinal roots from each spinal cord segment. The spinal nerve plexuses and the spinal roots are also included.Spinal Cord Diseases: Pathologic conditions which feature SPINAL CORD damage or dysfunction, including disorders involving the meninges and perimeningeal spaces surrounding the spinal cord. Traumatic injuries, vascular diseases, infections, and inflammatory/autoimmune processes may affect the spinal cord.Isoflurane: A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.Methyl Ethers: A group of compounds that contain the general formula R-OCH3.Anesthesiology: A specialty concerned with the study of anesthetics and anesthesia.Anesthetics, Combined: The use of two or more chemicals simultaneously or sequentially to induce anesthesia. The drugs need not be in the same dosage form.Spinal Nerve Roots: Paired bundles of NERVE FIBERS entering and leaving the SPINAL CORD at each segment. The dorsal and ventral nerve roots join to form the mixed segmental spinal nerves. The dorsal roots are generally afferent, formed by the central projections of the spinal (dorsal root) ganglia sensory cells, and the ventral roots are efferent, comprising the axons of spinal motor and PREGANGLIONIC AUTONOMIC FIBERS.Monitoring, Intraoperative: The constant checking on the state or condition of a patient during the course of a surgical operation (e.g., checking of vital signs).Spinal Cord Neoplasms: Benign and malignant neoplasms which occur within the substance of the spinal cord (intramedullary neoplasms) or in the space between the dura and spinal cord (intradural extramedullary neoplasms). The majority of intramedullary spinal tumors are primary CNS neoplasms including ASTROCYTOMA; EPENDYMOMA; and LIPOMA. Intramedullary neoplasms are often associated with SYRINGOMYELIA. The most frequent histologic types of intradural-extramedullary tumors are MENINGIOMA and NEUROFIBROMA.Spinal Canal: The cavity within the SPINAL COLUMN through which the SPINAL CORD passes.Nitrous Oxide: Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream.Spinal DiseasesSpinal Cord Compression: Acute and chronic conditions characterized by external mechanical compression of the SPINAL CORD due to extramedullary neoplasm; EPIDURAL ABSCESS; SPINAL FRACTURES; bony deformities of the vertebral bodies; and other conditions. Clinical manifestations vary with the anatomic site of the lesion and may include localized pain, weakness, sensory loss, incontinence, and impotence.Anesthetics: Agents that are capable of inducing a total or partial loss of sensation, especially tactile sensation and pain. They may act to induce general ANESTHESIA, in which an unconscious state is achieved, or may act locally to induce numbness or lack of sensation at a targeted site.Spinal NeoplasmsLidocaine: A local anesthetic and cardiac depressant used as an antiarrhythmia agent. Its actions are more intense and its effects more prolonged than those of PROCAINE but its duration of action is shorter than that of BUPIVACAINE or PRILOCAINE.Halothane: A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178)Spinal Stenosis: Narrowing of the spinal canal.Bupivacaine: A widely used local anesthetic agent.Spinal Fusion: Operative immobilization or ankylosis of two or more vertebrae by fusion of the vertebral bodies with a short bone graft or often with diskectomy or laminectomy. (From Blauvelt & Nelson, A Manual of Orthopaedic Terminology, 5th ed, p236; Dorland, 28th ed)Fentanyl: A potent narcotic analgesic, abuse of which leads to habituation or addiction. It is primarily a mu-opioid agonist. Fentanyl is also used as an adjunct to general anesthetics, and as an anesthetic for induction and maintenance. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1078)Anesthesia, Closed-Circuit: Inhalation anesthesia where the gases exhaled by the patient are rebreathed as some carbon dioxide is simultaneously removed and anesthetic gas and oxygen are added so that no anesthetic escapes into the room. Closed-circuit anesthesia is used especially with explosive anesthetics to prevent fires where electrical sparking from instruments is possible.Nerve Block: Interruption of NEURAL CONDUCTION in peripheral nerves or nerve trunks by the injection of a local anesthetic agent (e.g., LIDOCAINE; PHENOL; BOTULINUM TOXINS) to manage or treat pain.Anesthetics, General: Agents that induce various degrees of analgesia; depression of consciousness, circulation, and respiration; relaxation of skeletal muscle; reduction of reflex activity; and amnesia. There are two types of general anesthetics, inhalation and intravenous. With either type, the arterial concentration of drug required to induce anesthesia varies with the condition of the patient, the desired depth of anesthesia, and the concomitant use of other drugs. (From AMA Drug Evaluations Annual, 1994, p.173)Ketamine: A cyclohexanone derivative used for induction of anesthesia. Its mechanism of action is not well understood, but ketamine can block NMDA receptors (RECEPTORS, N-METHYL-D-ASPARTATE) and may interact with sigma receptors.Ambulatory Surgical Procedures: Surgery performed on an outpatient basis. It may be hospital-based or performed in an office or surgicenter.Preanesthetic Medication: Drugs administered before an anesthetic to decrease a patient's anxiety and control the effects of that anesthetic.Spinal Injuries: Injuries involving the vertebral column.Thiopental: A barbiturate that is administered intravenously for the induction of general anesthesia or for the production of complete anesthesia of short duration.Anesthesia, Caudal: Epidural anesthesia administered via the sacral canal.Muscular Atrophy, Spinal: A group of disorders marked by progressive degeneration of motor neurons in the spinal cord resulting in weakness and muscular atrophy, usually without evidence of injury to the corticospinal tracts. Diseases in this category include Werdnig-Hoffmann disease and later onset SPINAL MUSCULAR ATROPHIES OF CHILDHOOD, most of which are hereditary. (Adams et al., Principles of Neurology, 6th ed, p1089)Spinal Cord Ischemia: Reduced blood flow to the spinal cord which is supplied by the anterior spinal artery and the paired posterior spinal arteries. This condition may be associated with ARTERIOSCLEROSIS, trauma, emboli, diseases of the aorta, and other disorders. Prolonged ischemia may lead to INFARCTION of spinal cord tissue.Pentobarbital: A short-acting barbiturate that is effective as a sedative and hypnotic (but not as an anti-anxiety) agent and is usually given orally. It is prescribed more frequently for sleep induction than for sedation but, like similar agents, may lose its effectiveness by the second week of continued administration. (From AMA Drug Evaluations Annual, 1994, p236)Anesthetics, Dissociative: Intravenous anesthetics that induce a state of sedation, immobility, amnesia, and marked analgesia. Subjects may experience a strong feeling of dissociation from the environment. The condition produced is similar to NEUROLEPTANALGESIA, but is brought about by the administration of a single drug. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed)Ganglia, Spinal: Sensory ganglia located on the dorsal spinal roots within the vertebral column. The spinal ganglion cells are pseudounipolar. The single primary branch bifurcates sending a peripheral process to carry sensory information from the periphery and a central branch which relays that information to the spinal cord or brain.Enflurane: An extremely stable inhalation anesthetic that allows rapid adjustments of anesthesia depth with little change in pulse or respiratory rate.Xylazine: An adrenergic alpha-2 agonist used as a sedative, analgesic and centrally acting muscle relaxant in VETERINARY MEDICINE.Intraoperative Complications: Complications that affect patients during surgery. They may or may not be associated with the disease for which the surgery is done, or within the same surgical procedure.Intubation, Intratracheal: A procedure involving placement of a tube into the trachea through the mouth or nose in order to provide a patient with oxygen and anesthesia.Pain, Postoperative: Pain during the period after surgery.Conscious Sedation: A drug-induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation. No interventions are required to maintain a patent airway. (From: American Society of Anesthesiologists Practice Guidelines)Anesthesia Department, Hospital: Hospital department responsible for the administration of functions and activities pertaining to the delivery of anesthetics.Pain Measurement: Scales, questionnaires, tests, and other methods used to assess pain severity and duration in patients or experimental animals to aid in diagnosis, therapy, and physiological studies.Thoracic Vertebrae: A group of twelve VERTEBRAE connected to the ribs that support the upper trunk region.Spine: The spinal or vertebral column.Motor Neurons: Neurons which activate MUSCLE CELLS.Cesarean Section: Extraction of the FETUS by means of abdominal HYSTEROTOMY.Anesthesia, IntratrachealParaplegia: Severe or complete loss of motor function in the lower extremities and lower portions of the trunk. This condition is most often associated with SPINAL CORD DISEASES, although BRAIN DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; NEUROMUSCULAR DISEASES; and MUSCULAR DISEASES may also cause bilateral leg weakness.Intraoperative Period: The period during a surgical operation.Laminectomy: A surgical procedure that entails removing all (laminectomy) or part (laminotomy) of selected vertebral lamina to relieve pressure on the SPINAL CORD and/or SPINAL NERVE ROOTS. Vertebral lamina is the thin flattened posterior wall of vertebral arch that forms the vertebral foramen through which pass the spinal cord and nerve roots.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Tuberculosis, Spinal: Osteitis or caries of the vertebrae, usually occurring as a complication of tuberculosis of the lungs.Lumbosacral Region: Region of the back including the LUMBAR VERTEBRAE, SACRUM, and nearby structures.Prilocaine: A local anesthetic that is similar pharmacologically to LIDOCAINE. Currently, it is used most often for infiltration anesthesia in dentistry.Pain: An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS.Anesthesia and Analgesia: Medical methods of either relieving pain caused by a particular condition or removing the sensation of pain during a surgery or other medical procedure.Hematoma, Epidural, Spinal: A rare epidural hematoma in the spinal epidural space, usually due to a vascular malformation (CENTRAL NERVOUS SYSTEM VASCULAR MALFORMATIONS) or TRAUMA. Spontaneous spinal epidural hematoma is a neurologic emergency due to a rapidly evolving compressive MYELOPATHY.Methohexital: An intravenous anesthetic with a short duration of action that may be used for induction of anesthesia.Analgesics, Opioid: Compounds with activity like OPIATE ALKALOIDS, acting at OPIOID RECEPTORS. Properties include induction of ANALGESIA or NARCOSIS.Spinal Curvatures: Deformities of the SPINE characterized by abnormal bending or flexure in the vertebral column. They may be bending forward (KYPHOSIS), backward (LORDOSIS), or sideway (SCOLIOSIS).Lumbar Vertebrae: VERTEBRAE in the region of the lower BACK below the THORACIC VERTEBRAE and above the SACRAL VERTEBRAE.Posterior Horn Cells: Neurons in the SPINAL CORD DORSAL HORN whose cell bodies and processes are confined entirely to the CENTRAL NERVOUS SYSTEM. They receive collateral or direct terminations of dorsal root fibers. They send their axons either directly to ANTERIOR HORN CELLS or to the WHITE MATTER ascending and descending longitudinal fibers.Cervical Vertebrae: The first seven VERTEBRAE of the SPINAL COLUMN, which correspond to the VERTEBRAE of the NECK.Electroencephalography: Recording of electric currents developed in the brain by means of electrodes applied to the scalp, to the surface of the brain, or placed within the substance of the brain.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Mepivacaine: A local anesthetic that is chemically related to BUPIVACAINE but pharmacologically related to LIDOCAINE. It is indicated for infiltration, nerve block, and epidural anesthesia. Mepivacaine is effective topically only in large doses and therefore should not be used by this route. (From AMA Drug Evaluations, 1994, p168)Alfentanil: A short-acting opioid anesthetic and analgesic derivative of FENTANYL. It produces an early peak analgesic effect and fast recovery of consciousness. Alfentanil is effective as an anesthetic during surgery, for supplementation of analgesia during surgical procedures, and as an analgesic for critically ill patients.Hypnotics and Sedatives: Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety.Consciousness: Sense of awareness of self and of the environment.Postoperative Complications: Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.Surgical Procedures, Minor: Surgery restricted to the management of minor problems and injuries; surgical procedures of relatively slight extent and not in itself hazardous to life. (Dorland, 28th ed & Stedman, 25th ed)Spinal Muscular Atrophies of Childhood: A group of recessively inherited diseases that feature progressive muscular atrophy and hypotonia. They are classified as type I (Werdnig-Hoffman disease), type II (intermediate form), and type III (Kugelberg-Welander disease). Type I is fatal in infancy, type II has a late infantile onset and is associated with survival into the second or third decade. Type III has its onset in childhood, and is slowly progressive. (J Med Genet 1996 Apr:33(4):281-3)Midazolam: A short-acting hypnotic-sedative drug with anxiolytic and amnestic properties. It is used in dentistry, cardiac surgery, endoscopic procedures, as preanesthetic medication, and as an adjunct to local anesthesia. The short duration and cardiorespiratory stability makes it useful in poor-risk, elderly, and cardiac patients. It is water-soluble at pH less than 4 and lipid-soluble at physiological pH.Postoperative Nausea and Vomiting: Emesis and queasiness occurring after anesthesia.Hemodynamics: The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.Xenon: A noble gas with the atomic symbol Xe, atomic number 54, and atomic weight 131.30. It is found in the earth's atmosphere and has been used as an anesthetic.Sufentanil: An opioid analgesic that is used as an adjunct in anesthesia, in balanced anesthesia, and as a primary anesthetic agent.Double-Blind Method: A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.Reflex: An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.Spinal Fractures: Broken bones in the vertebral column.Analgesia: Methods of PAIN relief that may be used with or in place of ANALGESICS.Neuromuscular Nondepolarizing Agents: Drugs that interrupt transmission at the skeletal neuromuscular junction without causing depolarization of the motor end plate. They prevent acetylcholine from triggering muscle contraction and are used as muscle relaxants during electroshock treatments, in convulsive states, and as anesthesia adjuvants.EthersSpinal Puncture: Tapping fluid from the subarachnoid space in the lumbar region, usually between the third and fourth lumbar vertebrae.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.Epidural Space: Space between the dura mater and the walls of the vertebral canal.Surgical Procedures, Operative: Operations carried out for the correction of deformities and defects, repair of injuries, and diagnosis and cure of certain diseases. (Taber, 18th ed.)Chloralose: A derivative of CHLORAL HYDRATE that was used as a sedative but has been replaced by safer and more effective drugs. Its most common use is as a general anesthetic in animal experiments.Spinal Cord Regeneration: Repair of the damaged neuron function after SPINAL CORD INJURY or SPINAL CORD DISEASES.Morphine: The principal alkaloid in opium and the prototype opiate analgesic and narcotic. Morphine has widespread effects in the central nervous system and on smooth muscle.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.Ether: A mobile, very volatile, highly flammable liquid used as an inhalation anesthetic and as a solvent for waxes, fats, oils, perfumes, alkaloids, and gums. It is mildly irritating to skin and mucous membranes.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Medetomidine: An agonist of RECEPTORS, ADRENERGIC ALPHA-2 that is used in veterinary medicine for its analgesic and sedative properties. It is the racemate of DEXMEDETOMIDINE.Hyperalgesia: An increased sensation of pain or discomfort produced by mimimally noxious stimuli due to damage to soft tissue containing NOCICEPTORS or injury to a peripheral nerve.Piperidines: A family of hexahydropyridines.Analgesics: Compounds capable of relieving pain without the loss of CONSCIOUSNESS.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Ephedrine: A phenethylamine found in EPHEDRA SINICA. PSEUDOEPHEDRINE is an isomer. It is an alpha- and beta-adrenergic agonist that may also enhance release of norepinephrine. It has been used for asthma, heart failure, rhinitis, and urinary incontinence, and for its central nervous system stimulatory effects in the treatment of narcolepsy and depression. It has become less extensively used with the advent of more selective agonists.Quadriplegia: Severe or complete loss of motor function in all four limbs which may result from BRAIN DISEASES; SPINAL CORD DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; NEUROMUSCULAR DISEASES; or rarely MUSCULAR DISEASES. The locked-in syndrome is characterized by quadriplegia in combination with cranial muscle paralysis. Consciousness is spared and the only retained voluntary motor activity may be limited eye movements. This condition is usually caused by a lesion in the upper BRAIN STEM which injures the descending cortico-spinal and cortico-bulbar tracts.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Carticaine: A thiophene-containing local anesthetic pharmacologically similar to MEPIVACAINE.Consciousness Monitors: Devices used to assess the level of consciousness especially during anesthesia. They measure brain activity level based on the EEG.Hypotension: Abnormally low BLOOD PRESSURE that can result in inadequate blood flow to the brain and other vital organs. Common symptom is DIZZINESS but greater negative impacts on the body occur when there is prolonged depravation of oxygen and nutrients.Laryngeal Masks: A type of oropharyngeal airway that provides an alternative to endotracheal intubation and standard mask anesthesia in certain patients. It is introduced into the hypopharynx to form a seal around the larynx thus permitting spontaneous or positive pressure ventilation without penetration of the larynx or esophagus. It is used in place of a facemask in routine anesthesia. The advantages over standard mask anesthesia are better airway control, minimal anesthetic gas leakage, a secure airway during patient transport to the recovery area, and minimal postoperative problems.Neuromuscular Blocking Agents: Drugs that interrupt transmission of nerve impulses at the skeletal neuromuscular junction. They can be of two types, competitive, stabilizing blockers (NEUROMUSCULAR NONDEPOLARIZING AGENTS) or noncompetitive, depolarizing agents (NEUROMUSCULAR DEPOLARIZING AGENTS). Both prevent acetylcholine from triggering the muscle contraction and they are used as anesthesia adjuvants, as relaxants during electroshock, in convulsive states, etc.Trigeminal Nucleus, Spinal: Nucleus of the spinal tract of the trigeminal nerve. It is divided cytoarchitectonically into three parts: oralis, caudalis (TRIGEMINAL CAUDAL NUCLEUS), and interpolaris.Locomotion: Movement or the ability to move from one place or another. It can refer to humans, vertebrate or invertebrate animals, and microorganisms.Manipulation, Spinal: Adjustment and manipulation of the vertebral column.Recovery of Function: A partial or complete return to the normal or proper physiologic activity of an organ or part following disease or trauma.Neuromuscular Blockade: The intentional interruption of transmission at the NEUROMUSCULAR JUNCTION by external agents, usually neuromuscular blocking agents. It is distinguished from NERVE BLOCK in which nerve conduction (NEURAL CONDUCTION) is interrupted rather than neuromuscular transmission. Neuromuscular blockade is commonly used to produce MUSCLE RELAXATION as an adjunct to anesthesia during surgery and other medical procedures. It is also often used as an experimental manipulation in basic research. It is not strictly speaking anesthesia but is grouped here with anesthetic techniques. The failure of neuromuscular transmission as a result of pathological processes is not included here.Intraoperative Awareness: Occurence of a patient becoming conscious during a procedure performed under GENERAL ANESTHESIA and subsequently having recall of these events. (From Anesthesiology 2006, 104(4): 847-64.)Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Intraoperative Care: Patient care procedures performed during the operation that are ancillary to the actual surgery. It includes monitoring, fluid therapy, medication, transfusion, anesthesia, radiography, and laboratory tests.Brachial Plexus: The large network of nerve fibers which distributes the innervation of the upper extremity. The brachial plexus extends from the neck into the axilla. In humans, the nerves of the plexus usually originate from the lower cervical and the first thoracic spinal cord segments (C5-C8 and T1), but variations are not uncommon.Succinylcholine: A quaternary skeletal muscle relaxant usually used in the form of its bromide, chloride, or iodide. It is a depolarizing relaxant, acting in about 30 seconds and with a duration of effect averaging three to five minutes. Succinylcholine is used in surgical, anesthetic, and other procedures in which a brief period of muscle relaxation is called for.Laryngoscopy: Examination, therapy or surgery of the interior of the larynx performed with a specially designed endoscope.Orthopedic Procedures: Procedures used to treat and correct deformities, diseases, and injuries to the MUSCULOSKELETAL SYSTEM, its articulations, and associated structures.Paralysis: A general term most often used to describe severe or complete loss of muscle strength due to motor system disease from the level of the cerebral cortex to the muscle fiber. This term may also occasionally refer to a loss of sensory function. (From Adams et al., Principles of Neurology, 6th ed, p45)Manuals as Topic: Books designed to give factual information or instructions.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Hypotension, Controlled: Procedure in which arterial blood pressure is intentionally reduced in order to control blood loss during surgery. This procedure is performed either pharmacologically or by pre-surgical removal of blood.Respiration: The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (= OXYGEN CONSUMPTION) or cell respiration (= CELL RESPIRATION).Deep Sedation: Drug-induced depression of consciousness during which patients cannot be easily aroused but respond purposely following repeated painful stimulation. The ability to independently maintain ventilatory function may be impaired. (From: American Society of Anesthesiologists Practice Guidelines)Anterior Horn Cells: MOTOR NEURONS in the anterior (ventral) horn of the SPINAL CORD which project to SKELETAL MUSCLES.Neuralgia: Intense or aching pain that occurs along the course or distribution of a peripheral or cranial nerve.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Androstanols: Androstanes and androstane derivatives which are substituted in any position with one or more hydroxyl groups.Shivering: Involuntary contraction or twitching of the muscles. It is a physiologic method of heat production in man and other mammals.Myelography: X-ray visualization of the spinal cord following injection of contrast medium into the spinal arachnoid space.Subarachnoid Space: The space between the arachnoid membrane and PIA MATER, filled with CEREBROSPINAL FLUID. It contains large blood vessels that supply the BRAIN and SPINAL CORD.Nociceptors: Peripheral AFFERENT NEURONS which are sensitive to injuries or pain, usually caused by extreme thermal exposures, mechanical forces, or other noxious stimuli. Their cell bodies reside in the DORSAL ROOT GANGLIA. Their peripheral terminals (NERVE ENDINGS) innervate target tissues and transduce noxious stimuli via axons to the CENTRAL NERVOUS SYSTEM.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Etomidate: Imidazole derivative anesthetic and hypnotic with little effect on blood gases, ventilation, or the cardiovascular system. It has been proposed as an induction anesthetic.Afferent Pathways: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Sensation: The process in which specialized SENSORY RECEPTOR CELLS transduce peripheral stimuli (physical or chemical) into NERVE IMPULSES which are then transmitted to the various sensory centers in the CENTRAL NERVOUS SYSTEM.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Postoperative Period: The period following a surgical operation.Evoked Potentials, Somatosensory: The electric response evoked in the CEREBRAL CORTEX by stimulation along AFFERENT PATHWAYS from PERIPHERAL NERVES to CEREBRUM.Urethane: Antineoplastic agent that is also used as a veterinary anesthetic. It has also been used as an intermediate in organic synthesis. Urethane is suspected to be a carcinogen.Operating Rooms: Facilities equipped for performing surgery.Scoliosis: An appreciable lateral deviation in the normally straight vertical line of the spine. (Dorland, 27th ed)Cordotomy: Any operation on the spinal cord. (Stedman, 26th ed)Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Ophthalmologic Surgical Procedures: Surgery performed on the eye or any of its parts.Hernia, Inguinal: An abdominal hernia with an external bulge in the GROIN region. It can be classified by the location of herniation. Indirect inguinal hernias occur through the internal inguinal ring. Direct inguinal hernias occur through defects in the ABDOMINAL WALL (transversalis fascia) in Hesselbach's triangle. The former type is commonly seen in children and young adults; the latter in adults.Droperidol: A butyrophenone with general properties similar to those of HALOPERIDOL. It is used in conjunction with an opioid analgesic such as FENTANYL to maintain the patient in a calm state of neuroleptanalgesia with indifference to surroundings but still able to cooperate with the surgeon. It is also used as a premedicant, as an antiemetic, and for the control of agitation in acute psychoses. (From Martindale, The Extra Pharmacopoeia, 29th ed, p593)Blood Gas Analysis: Measurement of oxygen and carbon dioxide in the blood.Neurons, Afferent: Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.Decompression, Surgical: A surgical operation for the relief of pressure in a body compartment or on a body part. (From Dorland, 28th ed)Tetracaine: A potent local anesthetic of the ester type used for surface and spinal anesthesia.Needles: Sharp instruments used for puncturing or suturing.Hindlimb: Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Epinephrine: The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS.Nerve Regeneration: Renewal or physiological repair of damaged nerve tissue.Body Temperature: The measure of the level of heat of a human or animal.Amides: Organic compounds containing the -CO-NH2 radical. Amides are derived from acids by replacement of -OH by -NH2 or from ammonia by the replacement of H by an acyl group. (From Grant & Hackh's Chemical Dictionary, 5th ed)Oxygen: An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.Sciatic Nerve: A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.Dexmedetomidine: A imidazole derivative that is an agonist of ADRENERGIC ALPHA-2 RECEPTORS. It is closely-related to MEDETOMIDINE, which is the racemic form of this compound.Cervical Plexus: A network of nerve fibers originating in the upper four CERVICAL SPINAL CORD segments. The cervical plexus distributes cutaneous nerves to parts of the neck, shoulders, and back of the head. It also distributes motor fibers to muscles of the cervical SPINAL COLUMN, infrahyoid muscles, and the DIAPHRAGM.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Hypothermia: Lower than normal body temperature, especially in warm-blooded animals.Surgical Procedures, Elective: Surgery which could be postponed or not done at all without danger to the patient. Elective surgery includes procedures to correct non-life-threatening medical problems as well as to alleviate conditions causing psychological stress or other potential risk to patients, e.g., cosmetic or contraceptive surgery.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Analgesia, Epidural: The relief of pain without loss of consciousness through the introduction of an analgesic agent into the epidural space of the vertebral canal. It is differentiated from ANESTHESIA, EPIDURAL which refers to the state of insensitivity to sensation.Myelitis: Inflammation of the spinal cord. Relatively common etiologies include infections; AUTOIMMUNE DISEASES; SPINAL CORD; and ischemia (see also SPINAL CORD VASCULAR DISEASES). Clinical features generally include weakness, sensory loss, localized pain, incontinence, and other signs of autonomic dysfunction.Spinal Cord Stimulation: Application of electric current to the spine for treatment of a variety of conditions involving innervation from the spinal cord.Laryngismus: A disorder in which the adductor muscles of the VOCAL CORDS exhibit increased activity leading to laryngeal spasm. Laryngismus causes closure of the VOCAL FOLDS and airflow obstruction during inspiration.Acepromazine: A phenothiazine that is used in the treatment of PSYCHOSES.Mandibular Nerve: A branch of the trigeminal (5th cranial) nerve. The mandibular nerve carries motor fibers to the muscles of mastication and sensory fibers to the teeth and gingivae, the face in the region of the mandible, and parts of the dura.Clonidine: An imidazoline sympatholytic agent that stimulates ALPHA-2 ADRENERGIC RECEPTORS and central IMIDAZOLINE RECEPTORS. It is commonly used in the management of HYPERTENSION.Muscle Relaxants, Central: A heterogeneous group of drugs used to produce muscle relaxation, excepting the neuromuscular blocking agents. They have their primary clinical and therapeutic uses in the treatment of muscle spasm and immobility associated with strains, sprains, and injuries of the back and, to a lesser degree, injuries to the neck. They have been used also for the treatment of a variety of clinical conditions that have in common only the presence of skeletal muscle hyperactivity, for example, the muscle spasms that can occur in MULTIPLE SCLEROSIS. (From Smith and Reynard, Textbook of Pharmacology, 1991, p358)Dura Mater: The outermost of the three MENINGES, a fibrous membrane of connective tissue that covers the brain and the spinal cord.Nurse Anesthetists: Professional nurses who have completed postgraduate training in the administration of anesthetics and who function under the responsibility of the operating surgeon.Injections: Introduction of substances into the body using a needle and syringe.