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Chordae tendineae
Chordae tendineae, also called heart strings or tendinous cords, are collagen cords anchoring the mitral and tricuspid valve leaflets to the ventricular papillary muscles, preventing valve prolapse during contraction; rupture causes regurgitation and is repaired with ePTFE sutures.
Choroid
The choroid is the pigmented vascular middle layer of the eye (part of the uvea) supplying the outer retina and RPE, with five layers from Bruch's membrane to the suprachoroid, fed by posterior ciliary arteries and drained by 4-7 vortex veins.
Choroid plexus
Choroid plexus: secretory epithelial tissue in the brain's four ventricles that produces most cerebrospinal fluid, forms the blood-CSF barrier via tight junctions, and aids immune surveillance.
Choroid plexus cyst
Choroid plexus cyst (CPC), a fluid-filled cyst in the choroid plexus, found in 0.5–2.5% of second-trimester fetuses; usually resolves by 26–28 weeks; isolated cysts are benign, but CPCs can mark trisomy 18 risk when other findings are present.
Choroidal rupture
Choroidal rupture: a traumatic break in Bruch's membrane, choriocapillaris, and RPE after blunt ocular trauma (ICD-11 NA06.61). Direct or indirect (countercoup) forms; main complication choroidal neovascularization treated with anti-VEGF.
Choroideremia
Choroideremia, also called progressive tapetochoroidal dystrophy (TCD), is an X-linked recessive retinal degeneration caused by CHM gene mutations, causing childhood night blindness, tunnel vision, and late blindness in males.
Christopher and Dana Reeve Foundation
Christopher & Dana Reeve Foundation, also called the Reeve Foundation, is a Short Hills, New Jersey 501(c)(3) nonprofit founded in 1982 as the Stifel Paralysis Research Foundation, merged with the American Paralysis Association, funding spinal cord injury research and the National Paralysis Resource Center.
Chronic atticoantral suppurative otitis media
Chronic atticoantral suppurative otitis media (ICD-11 AA91.1, ICD-10 H66.2) is the unsafe CSOM subtype with posterosuperior pars tensa or pars flaccida marginal perforation, attic and mastoid disease, cholesteatoma risk, bone erosion, and mastoidectomy treatment.
Chronic bilateral vestibulopathy
Chronic bilateral vestibulopathy (BVP, bilateral vestibular hypofunction) is a chronic vestibular syndrome with bilaterally reduced angular VOR causing unsteadiness, oscillopsia, and worsening in darkness; diagnosed by vHIT gain <0.6 or caloric sum <6°/sec, treated mainly with vestibular rehabilitation.
Chronic cervical lymphadenitis
Chronic cervical lymphadenitis, also called chronic inflammation of cervical lymph node (SNOMED 788889007), is persistent neck node inflammation beyond 6 weeks, caused mainly by nontuberculous mycobacteria, tuberculosis, cat-scratch disease, or malignancy.
Chronic congestive splenomegaly
Chronic congestive splenomegaly (ICD-10 D73.2, ICD-11 3B81.C; also spleen hyperaemia, Opitz disease) is long-term spleen enlargement from portal hypertension or splenic vein thrombosis, causing red pulp congestion, fibrosis, and pancytopenia.
Chronic coronary artery disease
Chronic coronary artery disease is the established, non-acute phase of atherosclerosis in the heart's arteries, covering obstructive and nonobstructive disease, prior heart attack, and chronic angina.
Chronic inflammation of postmastoidectomy cavity
Chronic inflammation of postmastoidectomy cavity (ICD-11 AB93; ICD-10-CM H95.11) is persistent inflammation of the open mastoid cavity after canal wall down mastoidectomy, causing therapy-resistant otorrhea in over 20% of open-cavity patients, treated topically or by revision obliteration surgery.
Chronic mastoiditis
Chronic mastoiditis (ICD-11 AB11.1, ICD-10 H70.1) is persistent or recurrent inflammation of the mastoid bone lasting over a month, usually a complication of chronic suppurative otitis media or cholesteatoma, treated with IV antibiotics and mastoidectomy.
Chronic myringitis
Chronic myringitis, also called granular myringitis or myringitis granulosa, is persistent inflammation and epithelial loss of the tympanic membrane lasting over one month without middle ear disease, causing painless otorrhea and treated with topical agents, laser, or surgery.
Chronic otitis media
Chronic otitis media (COM, chronic suppurative otitis media, CSOM) is persistent middle ear inflammation with eardrum perforation, discharge, and hearing loss, affecting about 3.8% of people worldwide, mostly in low- and middle-income countries.
Chronic suppurative otitis media
Chronic suppurative otitis media (CSOM), also called chronic otitis media, is a chronic middle ear infection with discharge through a perforated eardrum and hearing loss; about 297 million people are affected, mostly in low- and middle-income countries, and treatment centers on ear cleaning and topical quinolone drops.
Chronic tubotympanic suppurative otitis media
Chronic tubotympanic suppurative otitis media (CSOM, tubotympanic type, ICD-11 AA91.0) is a chronic middle ear infection with a persistent pars tensa perforation, recurrent ear discharge, and 20-60 dB conductive hearing loss, treated with topical quinolones and surgery.
Chronic vascular disorders of intestine
Chronic vascular disorders of intestine, ICD-10-CM K55.1 and ICD-11 DD31, covers long-standing intestinal blood-flow disorders, chiefly chronic mesenteric ischaemia from atherosclerosis, causing postprandial pain and weight loss.
Chronic venous insufficiency
Chronic venous insufficiency (CVI), also called venous reflux disease, is impaired leg-vein return of blood from valve failure or obstruction, causing swelling, varicose veins, and ulcers; diagnosed by duplex ultrasound and treated with compression and ablation.
Chylomicron
Chylomicrons are the largest, least dense lipoproteins (75–1,200 nm, apoB-48 particles) assembled in intestinal enterocytes to carry dietary triglycerides via lacteals and the thoracic duct; lipoprotein lipase converts them to remnants cleared by the liver.
Chylothorax
Chylothorax: chyle accumulation in the pleural space, usually from thoracic duct injury or obstruction. Also chylous pleural effusion. Diagnosed by pleural triglyceride >110 mg/dL; caused mostly by surgery or lymphoma.
Chylous ascites
Chylous ascites: leakage of triglyceride-rich lymph (chyle) into the peritoneal cavity, milky fluid with triglyceride >200 mg/dL; caused by malignancy, cirrhosis, tuberculosis, or lymphatic injury; treated conservatively first.
Chylous effusion
Chylous effusion (chylothorax): accumulation of chyle in the pleural space, about 3% of pleural effusions. Diagnosed by pleural triglyceride >110 mg/dL; caused mainly by trauma, surgery, and malignancy, especially lymphoma.
Chyme
Chyme is the acidic semifluid mass of partly digested food formed in the stomach and released through the pylorus into the duodenum, where bile and pancreatic juice neutralize it; distinct from chyle, the milky fat-rich lymph of the small intestine.
Cicatricial lagophthalmos
Cicatricial lagophthalmos, a mechanical form of lagophthalmos (ICD-11 9A03.40), is incomplete eyelid closure caused by scarring after eyelid surgery, trauma, or burns, treated with lubrication and scar release with grafting.
Cicatrizing conjunctivitis
Cicatrizing conjunctivitis, also called cicatricial conjunctivitis, is a rare vision-threatening group of disorders causing conjunctival inflammation and scarring, most often from mucous membrane pemphigoid or Stevens-Johnson syndrome.
CIELAB color space
CIELAB (CIE 1976 L*a*b) is the CIE's 1976 perceptually oriented, device-independent color space with L lightness, a green-red and b blue-yellow axes, ΔE*ab Euclidean color difference, based on Hunter-Lab and ANLAB, used in printing, ICC, and color QC.
Ciliary muscle
The ciliary muscle (musculus ciliaris) is a ring of smooth muscle in the eye's ciliary body whose contraction lets the lens focus on near objects, a process called accommodation.
Cilostazol
Cilostazol (Pletal, Ekistol) is a PDE3 and adenosine-uptake inhibitor approved in 1999 for intermittent claudication in peripheral arterial disease; contraindicated in heart failure, EMA-restricted in 2011, with 40-60% walking-distance gains versus placebo.