Medical Dictionary

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periependymal (per′e-e-pen′di-mal)
Surrounding the ependyma.

periesophageal (per′e-e-sof′a-je′al)
Surrounding the esophagus.

periesophagitis (per′e-e-sof′a-ji′tis)
Inflammation of the tissues surrounding the esophagus.

perifocal (per-i-fo′kal)
Surrounding a focus; denoting tissues, or the blood that they contain, in the vicinity of an infective focus.

perifollicular (per′i-fo-lik′u-lar)
Surrounding a hair follicle; usually used to describe the histopathologic appearance of the infiltrate surrounding a hair follicle.

perifolliculitis (per′i-fo-lik′u-li′tis)
The presence of an inflammatory infiltrate surrounding hair follicles; frequently occurs in conjunction with folliculitis. p. abscedens et suffodiens a chronic dissecting folliculitis of the scalp. SYN: dissecting cellulitis.

perifuse (per′i-fus)
To flush a fresh supply of bathing fluid around all of the outside surfaces of a small piece of tissue immersed in it. Cf.:perfuse, superfuse. [peri- + L. fusio, a pouring]

perifusion (per-i-fu′shun)
The act of perifusing.

periganglionic (per′i-gang-gle-on′ik)
Surrounding a ganglion, especially a nerve ganglion.

perigastric (per-i-gas′trik)
Surrounding the stomach. [peri- + G. gaster, belly, stomach]

perigastritis (per′i-gas-tri′tis)
Inflammation of the peritoneal coat of the stomach.

perigemmal (per′i-jem′al)
SYN: circumgemmal. [peri- + L. gemma, bud]

periglandulitis (per′i-glan-doo-li′tis)
Inflammation of the tissues surrounding a gland.

periglottic (per-i-glot′ik)
Around the tongue, especially around the base of the tongue and the epiglottis, or around the glottis (laryngis), the rima glottidis. [peri- + G. glossa or glotta, tongue]

periglottis (per-i-glot′is)
The mucous membrane of the tongue. [G. p., covering of the tongue]

perihepatic (per-i-he-pat′ik)
Surrounding the liver. [peri- + G. hepar, liver]

perihepatitis (per′i-hep-a-ti′tis)
Inflammation of the serous, or peritoneal, covering of the liver. SYN: hepatic capsulitis, hepatitis externa, hepatoperitonitis. [peri- + G. hepar, liver, + -itis, inflammation]

perihernial (per-i-her′ne-al)
Surrounding a hernia.

peri-implantoclasia (per′e-im-plan′to-kla′ze-a)
In dentistry, a general term implying disease of the supporting bone involving an implant; the disease may be exfoliative, resorptive, traumatic, or ulcerative in nature. [peri- + L. im, in, + planto, to plant, + G. klasis, breaking up]

perijejunitis (per′i-je-joo-ni′tis)
Inflammation around the jejunum.

perikaryon, pl .perikarya (per-i-kar′e-on, -a)
1. The cytoplasm around the nucleus, such as that of the cell body of nerve cells. 2. The body of the odontoblast, excluding the dentinal fiber. 3. The cell body of the nerve cell, as distinguished from its axon and dendrites. [peri- + G. karyon, kernel]

perikeratic (per-i-ke-rat′ik)
SYN: pericorneal. [peri- + G. keras, horn]

perikymata, gen. perikyma (per-i-ki′ma-ta, -ki′ma)
The transverse ridges and grooves on the surface of tooth enamel. [peri- + G. kyma, wave]

perilabyrinthitis (per′i-lab′i-rin-thi′tis)
Inflammation of the parts about the labyrinth.

perilaryngeal (per′i-la-rin′je-al)
Surrounding the larynx.

perilenticular (per-i-len-tik′u-lar)
Surrounding the lens of the eye. SYN: circumlental.

periligamentous (per′i-lig-a-men′tus)
SYN: peridesmic.

perilymph (per′i-limf) [TA]
The fluid contained within the osseus labyrinth, surrounding and protecting the membranous labyrinth; p. resembles extracellular fluid in composition (sodium salts are the predominate positive electrolyte) and, via the perilymphatic duct, is in continuity with cerebrospinal fluid. SYN: perilympha [TA] , Cotunnius liquid, liquor cotunnii.

perilympha (per′i-lim′fa) [TA]
SYN: perilymph. [peri- + L. lympha, a clear fluid (lymph)]

perilymphangial (per′i-lim-fan′je-al)
Surrounding a lymphatic vessel.

perilymphangitis (per′i-lim-fan-ji′tis)
Inflammation of the tissues surrounding a lymphatic vessel.

perilymphatic (per′i-lim-fat′ik)
1. Surrounding a lymphatic structure (node or vessel). 2. The spaces and tissues surrounding the membranous labyrinth of the inner ear.

perimeningitis (per′i-men-in-ji′tis)
SYN: pachymeningitis.

perimenopause (per′i-men′o-paws)
The 3–5-year period prior to menopause during which estrogen levels begin to drop.

perimeter (pe-rim′e-ter)
1. A circumference, edge, or border. 2. An instrument, usually half a circle or sphere, used to measure the field of vision. [G. perimetros, circumference, fr. peri, around, + metron, measure] arc p. a p. consisting of a semicircular frame at the center of which the patient looks while a white object is moving along the arc, the exact point where it becomes visible or invisible being noted and recorded on a chart. Goldmann p. a projection p. that adds further precision by controlling the surrounding illumination. projection p. a p. that uses as target a spot of light that can be adjusted rapidly as to size, brightness, and color, and moves silently at any desired speed. Tübinger p. a bowl p. in which a static stimulus was increased in intensity until detected. [Tübingen, German city]

perimetric (per-i-met′rik)
1. Surrounding the uterus; relating to the perimetrium. SYN: periuterine. [G. peri, around, + metra, uterus] 2. Relating to the circumference of any part or area. [G. perimetros, circumference] 3. Relating to perimetry.

perimetritic (per-i-me-trit′ik)
Relating to or marked by perimetritis.

perimetritis (per′i-me-tri′tis)
Inflammation of the uterus involving the perimetreal covering. SYN: metroperitonitis. [perimetrium + G. -itis, inflammation]

perimetrium, pl .perimetria (per-i-me′tre-um, -a) [TA]
The serous (peritoneal) coat of the uterus. SYN: tunica serosa uteri [TA] . [peri- + G. metra, uterus]

perimetry (pe-rim′e-tre)
1. The determination of the limits of the visual field. 2. The mapping of the sensitivity contours of the visual field. [G. perimetros, circumference] computed p. determination of the visual field by means of a programmed routine of static stimuli. flicker p. a technique of p. using the criterion of critical fusion frequency. SYN: flicker fusion frequency technique. kinetic p. mapping of the visual field by using a moving rather than a static test object. mesopic p. exploration of the visual field in dim illumination. objective p. determination of the visual field by pupillary constriction, electroencephalography, or eye movements. quantitative p. a plotting of the visual field in isopters of equal retinal sensitivity. scotopic p. p. of a dark-adapted eye. static p. determination of the visual field by using test objects at fixed positions and gradually increasing luminance to the threshold of visibility.

perimolysis (per-e-mol′i-sis)
Decalcification of the teeth from exposure to gastric acid in individuals with chronic vomiting. [=perimylolysis, fr. peri- + G. mylos, molar + lysis, loosening, dissolving, fr. luo, to loosen]

perimyelis (per-i-mi′e-lis)
SYN: endosteum. [peri- + G. myelos, marrow]

perimyelitis (per′i-mi-e-li′tis)
SYN: endosteitis.

perimyocarditis (per-i-mi′o-kar-di-tis)
Simultaneous pericarditis and myocarditis usually due to the same etiologic agent.

perimyositis (per′i-mi-o-si′tis)
Inflammation of the loose cellular tissue surrounding a muscle. SYN: perimysiitis (2) , perimysitis.

perimysial (per-i-mis′e-al, -miz′e-al)
Relating to the perimysium; surrounding a muscle.

perimysiitis, perimysitis (per′i-mis-e-i′tis, -mi-si′tis)
1. Inflammation of the perimysium. 2. SYN: perimyositis.

perimysium, pl .perimysia (per-i-mis′e-um, -miz′e-um; -e-a) [TA]
The fibrous sheath enveloping each of the fascicles of skeletal muscle fibers. [peri- + G. mys, muscle] p. externum SYN: epimysium. p. internum in the older literature, a term referring to the connective tissue around secondary and tertiary fascicles and individual fibers and also to the supporting framework of the myocardium.

perinatal (per-i-na′tal)
Occurring during, or pertaining to, the periods before, during, or after the time of birth; i.e., before delivery from the 22nd week of gestation through the first 28 days after delivery. [peri- + L. natus, pp. of nascor, to be born]

perinate (per′i-nat)
An infant in the perinatal period.

perinatologist (per-i-na-tol′o-jist)
An obstetrician who subspecializes in perinatology.

perinatology (per-i-na-tol′o-je)
A subspeciality of obstetrics concerned with care of the mother and fetus during pregnancy, labor, and delivery, particularly when the mother and/or fetus are at a high risk for complications. SYN: perinatal medicine.

perineal (per′i-ne′al)
Relating to the perineum.

perineo-
The perineum. [L. fr. G. perineos, perinaion]

perineocele (per-i-ne′o-sel)
A hernia in the perineal region, either between the rectum and the vagina or the rectum and the bladder, or alongside the rectum. [perineo- + G. kele, hernia]

perineometer (per′i-ne-om′e-ter)
Instrument used to measure the strength of voluntary muscle contractions of the perineum. [perineo- + G. metron, measure]

perineoplasty (per-i-ne′o-plas-te)
Plastic surgery of the perineum. [perineum + G. plastos, formed]

perineorrhaphy (per-i-ne-or′a-fe)
Suture of the perineum, performed in perineoplasty. [perineum + G. rhaphe, a sewing]

perineoscrotal (per-i-ne′o-skro′tal)
Relating to the perineum and the scrotum.

perineostomy (per-i-ne-os′to-me)
Urethrostomy through the perineum. [perineo- + G. stoma, mouth]

perineosynthesis (per′i-ne-o-sin′the-sis)
Rarely used term for perineoplasty in a case of extensive laceration of the perineum.

perineotomy (per-i-ne-ot′o-me)
Incision into the perineum to facilitate childbirth. SEE ALSO: episiotomy.

perineovaginal (per-i-ne′o-vaj′i-nal)
Relating to the perineum and the vagina.

perinephrial (per′i-nef′re-al)
Relating to the perinephrium.

perinephric (per′i-nef′rik)
Surrounding the kidney in whole or part. SYN: circumrenal, perirenal.

perinephritis (per′i-ne-fri′tis)
Inflammation of perinephric tissue.

perinephrium, pl .perinephria (per′i-nef′re-um, -nef′re-a)
The connective tissue and fat surrounding the kidney. [peri- + G. nephros, kidney]

perineum, pl .perinea (per′i-ne′um, -ne′a) [TA]
1. [NA] The area between the thighs extending from the coccyx to the pubis and lying below the pelvic diaphragm. 2. The external surface of the central tendon of the p., lying between the vulva and the anus in the female and the scrotum and the anus in the male. [L. fr. G. perineon, perinaion] watering-can p. a p. riddled with fistulas resulting from urethral stricture.

perineural (per′i-noo′ral)
Surrounding a nerve. [peri- + G. neuron, nerve]

perineurial (per′i-noo′re-al)
Relating to the perineurium.

perineuritis (per′i-noo-ri′tis)
Inflammation of the perineurium. SEE ALSO: adventitial neuritis.

perineurium, pl .perineuria (per-i-noo′re-um, -re-a)
One of the supporting structures of peripheral nerve trunks, consisting of layers of flattened cells and collagenous connective tissue, which surround the nerve fasciculi and form the major diffusion barrier within the nerve; with the endoneurium and epineurium, composes the peripheral nerve stroma. [L. fr. peri- + G. neuron, nerve]

perinuclear (per-i-noo′kle-ar)
Surrounding a nucleus. SYN: circumnuclear.

periocular (per-i-ok′u-lar)
SYN: circumocular.

period (per′e-od)
1. A certain duration or division of time. 2. One of the stages of a disease, e.g., p. of incubation, p. of convalescence. SEE ALSO: stage, phase. 3. Colloquialism for menses. 4. Any of the horizontal rows of chemical elements in the periodic table. [G. periodos, a way round, a cycle, fr. peri, around, + hodos, way] absolute refractory p. the p. following excitation when no response is possible regardless of the intensity of the stimulus. amblyogenic p. p. during early visual development when the visual neurosensory system is vulnerable to developing amblyopia from blurred retinal image formation, bilateral cortical suppression (as in strabismic amblyopia), or both. SYN: critical p. (3) . critical p. 1. in the first hours after birth, the p. of maximum imprintability; the p. before and after which imprinting is difficult or impossible; 2. in animals, a p. following birth when the processes underlying the capacity for socialization are activated or stamped in; 3. SYN: amblyogenic p.. eclipse p. the time between infection by (or induction of) a bacteriophage, or other virus, and the appearance of mature virus within the cell; an interval of time during which viral infectivity cannot be recovered. SYN: eclipse phase. effective refractory p. the p. during which impulses may appear but are too weak to be conducted; the longest interval between adequate stimuli, falling just short of the time necessary to allow a propagated response to be evoked in a tissue by the second stimulus; it differs from the functional refractory p. in that it is a measure of stimulus interval rather than response interval of time. ejection p. SYN: sphygmic interval. extrinsic incubation p. (eks-trin′sik) time required for the development of a disease agent in a vector, from the time of uptake of the agent to the time when the vector is infective. fertile p. the p. in a regularly menstruating woman's cycle, during which conception is most likely. functional refractory p. the minimum interval possible between successive responses to stimulation of a tissue. gap1 p. the p. of the cell cycle after cell division when there is synthesis of RNA and protein; it may last for a few hours in rapidly growing tissue or a lifetime in non-renewing cells such as nerve cells. SYN: gap1 phase, postmitotic phase. gap2 p. the p. in the cell cycle when synthesis of DNA is completed but before mitosis begins. SYN: gap2 phase, premitotic phase. gap0 p. phase of a cell no longer in the cell cycle and thus at least temporarily incapable of division. SYN: gap0 phase. incubation p. 1. time interval between invasion of the body by an infecting organism and the appearance of the first sign or symptom it causes; SYN: incubative stage, latent p. (2) , latent stage, stage of invasion. 2. in a disease vector, the p. between entry of the disease organism and the time at which the vector is capable of transmitting the disease to another human host. induction p. the p. required for a specific agent to produce a disease; the interval from the causal action of a factor to initiation of disease, e.g., the interval between exposure to radiation and the onset of leukemia; the interval between an initial injection of antigen and the appearance of demonstrable antibodies in the blood. intrapartum p. in obstetrics, the p. from the onset of labor to the end of the third stage of labor. isoelectric p. an abnormal p. occurring in the electrocardiogram between the end of the S wave and the beginning of the T wave during which electrical forces are acting in directions so as to neutralize each other so that there is no difference in potential under the electrodes. SYN: abnormal ST segment. isometric p. of cardiac cycle that p. in which the muscle fibers do not shorten although the cardiac muscle is excited and the pressure in the ventricles rises, extending from the closure of the atrioventricular valves to the opening of the semilunar valves (isovolumic constriction) or the reverse (isovolumic relaxation). SYN: isovolumic p.. isometric contraction p. the time between closure of the atrioventricular valves and opening of the semilunar valves. isometric relaxation p. early ventricular diastole beginning with closure of the aortic and pulmonic valves and preceding opening of the atrioventricular valves. isovolumic p. SYN: isometric p. of cardiac cycle. latency p. SYN: latency phase. latent p. 1. the p. elapsing between the application of a stimulus and the response, e.g., contraction of a muscle; 2. SYN: incubation p. (1) . masticatory silent p. a pause in electromyographic patterns associated with tooth contacts during chewing and biting; a part of the complex feedback mechanism of mandibular control involving receptors in the periodontal ligament and muscles. menstrual p. SYN: menses. missed p. the failure of menstruation to occur in any month at the expected time. mitotic p. the p. of the cell cycle in which all phases of mitosis occur. SYN: M phase. oedipal p. SYN: oedipal phase. preejection p. the interval between onset of QRS complex and cardiac ejection; electromechanical systole minus ejection time. prepatent p. in parasitology, the p. equivalent to the incubation p. of microbial infections; it is biologically different, however, because the parasite is undergoing developmental stages in the host. prodromal p. the time during which a disease process has begun but is not yet clinically manifest. puerperal p. the p. elapsing between the termination of labor and the return of the generative tract to its normal condition; the 6 weeks following the completion of labor. pulse p. the reciprocal of the repetition rate; e.g., the interval between leading edges of successive pulses. quarantine p. the time during which an infected individual or an area is kept isolated, avoiding contact with uninfected individuals; can be any specified p. of time, varying with the disease in question. The term is derived from the Italian word for 40, since the p. of isolation of individuals suspected of plague in the Middle Ages was 40 days. refractory p. 1. the p. following effective stimulation, during which excitable tissue such as heart muscle and nerve fails to respond to a stimulus of threshold intensity ( i.e., excitability is depressed); 2. a p. of temporary psychophysiologic resistance to further sexual stimulation that occurs immediately following orgasm. refractory p. of electronic pacemaker the time required to restore full sensitivity after detecting cardiac activity or delivering a pacing impulse. relative refractory p. the p. between the effective refractory p. and the end of the refractory p.; fibers then respond only to high-intensity stimuli and the impulses conduct more slowly than normally. silent p. 1. the time during which there is no electrical activity in a muscle following its rapid unloading; 2. any pause in an otherwise continuous series of electrophysiologic events. synthesis p. the p. of the cell cycle when there is synthesis of DNA and histone; it occurs between Gap1 and Gap2. SYN: S phase. total refractory p. the absolute refractory p. plus the relative refractory p.. vulnerable p., vulnerable p. of heart a brief time during the cardiac cycle when stimuli are particularly likely to induce repetitive activity like tachycardia, flutter, or fibrillation which persists after the stimulus has ceased; for the ventricle, it occurs during the latter part of systole, during the relative refractory p. coincident with the inscription of the latter half of the T wave of the electrocardiogram. Wenckebach p. a sequence of cardiac cycles in the electrocardiogram ending in a dropped beat due to AV block, the preceding cycles showing progressively lengthening PR intervals; the PR interval following the dropped beat is again shortened.

periodate (per-i′o-dat)
A salt of periodic acid.

periodic (per-e-od′ik)
1. Recurring at regular intervals. 2. Denoting a disease with regularly recurring exacerbations or paroxysms. 3. Denoting any of several oxoacids of iodine.

periodic acid (per-i′o-dik)
1. HIO4, but existing in solution usually in hydrated form; used in carbohydrate detection and analysis. SYN: metaperiodic acid. 2. Any of several iodic(VII) acids formed by the combination of iodine heptoxide, I2O7, with water.

periodicity (per′e-o-dis′i-te)
Tendency to recurrence at regular intervals. diurnal p. a circadian rhythm with primary expression of the p. during daylight hours, as in the release of microfilariae of Loa loa into the peripheral blood during the day, with far fewer released at night; associated with the day-biting habits of the vector, Chrysops species. filarial p. the circadian rhythm observed in the appearance of filarial microfilariae in the peripheral blood. SEE ALSO: diurnal p., nocturnal p.. lunar p. any rhythmic phenomenon that follows a lunar or monthly cycle. malarial p. a clinical rhythmicity reflected in periodic fevers and chills recurring at approximately 48-hour intervals in tertian malaria (Plasmodium vivax or P. ovale) or at 72-hour intervals in quartan malaria (P. malariae); the rhythm of tertian or 48-hour cycles is frequently modified in malignant tertian or falciparum malaria (P. falciparum); associated with release of merozoites from red cells during erythrocytic schizogony, although the controlling mechanism for the synchronous release is unknown. nocturnal p. a circadian rhythm with the p. expressed during nighttime hours, as in the night release of microfilariae of the human filaria Wuchereria bancrofti into the peripheral blood; this type of p. is found in regions where the vector mosquito is a night-biting species. subperiodic p. a modified circadian rhythm in which the p. is not clearcut, as in certain zoonotic strains of Malayan filariasis caused by Brugia malayi; as in examples of strict filarial p., this response is correlated with the biting habits of the vector insect (mosquito), although the precise mechanism inducing this microfilarial response is not clearly established.

periodontal (per′e-o-don′tal)
Around a tooth. SYN: paradental, pericemental, peridental. [peri- + G. odous, tooth]

Periodontal Disease Index (PDI)
An index used for estimating the degree of periodontal disease based on the measurement of six representative teeth for gingival inflammation, pocket depth, calculus and plaque, attrition, mobility, and lack of contact.

Periodontal Index (PI)
An index for the epidemiologic classification of periodontal disease.

periodontia (per′e-o-don′she-a)
1. Plural of periodontium. 2. SYN: periodontics.

periodontics (per′e-o-don′tiks)
The branch of dentistry concerned with the study of the normal tissues and the treatment of abnormal conditions of the tissues immediately about the teeth. SYN: periodontia (2) . [peri- + G. odous, tooth]

periodontist (per′e-o-don′tist)
A dentist who specializes in periodontics.

periodontitis (per′e-o-don-ti′tis)
1. Inflammation of the periodontium. 2. A chronic inflammatory disease of the periodontium occurring in response to bacterial plaque on the adjacent teeth; characterized by gingivitis, destruction of the alveolar bone and periodontal ligament, apical migration of the epithelial attachment resulting in the formation of periodontal pockets, and ultimately loosening and exfoliation of the teeth. [periodontium + G. -itis, inflammation] apical p. inflammation of the periodontal ligament surrounding the root apex of a tooth; usually a consequence of pulpal inflammation or necrosis. p. complex vertical resorption of the alveolar process with pockets of uneven depth on adjacent teeth, and with traumatic occlusion as a factor. juvenile p. a degenerative periodontal disease of adolescents in which the periodontal destruction is out of proportion to the local irritating factors present on the adjacent teeth; inflammatory changes become superimposed, and bone loss, migration, and extrusion are observed. Two forms are recognized: 1) localized, in which the destruction is limited to the incisors and first molars; 2) generalized, involving all of the teeth. SYN: periodontosis. p. simplex horizontal resorption of the alveolar process with pockets of even depth on adjacent teeth; traumatic occlusion is not a factor. suppurative p. p. accompanied by purulent exudate.

periodontium, pl .periodontia (per′e-o-don′she-um, -she-a) [TA]
The connective tissue that surrounds the tooth root and attaches it to its bony socket; it consists of fibers anchored in the cementum and extending into the alveolar bone; the tissues that surround and support the teeth, including the gingivae, cementum, desmodentium, periodontal fibrs, and alveolar and supporting bone. SYN: periodontal ligament [TA] , periodontal membrane&star, alveolar periosteum, periosteum alveolare, alveolodental ligament, alveolodental membrane, gingivodental ligament, paradentium, parodontium, peridental ligament, peridental membrane, peridentium, tapetum alveoli. [L. fr. peri- + G. odous, tooth]

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