2,701 articles
Intravenous sugar solution
Intravenous sugar solution (dextrose or glucose IV infusion, e.g. D5W): sterile 5% glucose in water supplying calories and water, first infused in 1896; physiologically hypotonic after metabolism, with hyponatremia and hyperglycemia as key risks.
Intravenous therapy
Intravenous therapy, also known as IV therapy or an intravenous drip, is a medical technique that delivers fluids, medications, nutrition, or blood products directly into a vein, bypassing the gut.
Intrinsic primary afferent neuron of myenteric plexus
Intrinsic primary afferent neuron (IPAN), also called enteric primary afferent neuron or intrinsic sensory neuron: a sensory neuron with cell bodies in the myenteric and submucosal plexuses that transduces gut mechanical and chemical stimuli, has Dogiel type II morphology and AH electrophysiology, initiates local enteric reflexes, and does not project to the CNS.
Intrinsically photosensitive retinal ganglion cell
Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called melanopsin-expressing RGCs, are a third retinal photoreceptor class: about 1–2% of ganglion cells, six subtypes, mediating circadian entrainment, pupillary reflex, sleep, and mood.
Ioflupane (123I)
Ioflupane (123I), sold as DaTscan, is a radioactive cocaine analog that binds the dopamine transporter for SPECT imaging in parkinsonian syndromes and dementia with Lewy bodies.
Iris (anatomy)
Iris (anatomy): the colored diaphragm of the eye surrounding the pupil. Its sphincter and dilator muscles adjust pupil size to control light entry; melanin determines eye color, and its pattern is unique like a fingerprint.
Ischaemic optic neuropathy
Ischaemic optic neuropathy (ION, ischemic optic neuropathy): sudden painless vision loss from optic nerve infarction. Anterior (AION) and posterior (PION) forms; nonarteritic AION is the leading acute optic neuropathy over age 50, with no proven treatment.
Ischium
Ischium (os ischii), the sit bone: posterior-inferior third of the hip bone, formed of body and ramus, bearing the ischial tuberosity, ischial spine, and sciatic notches, and contributing to the acetabulum.
ISCoPE trial
ISCoPE (Injured Spinal Cord Pressure Evaluation, NCT02721615) is an ongoing St George's, University of London observational trial monitoring intraspinal pressure at the injury site after severe traumatic spinal cord injury, showing elevated pressure, compartmentalization, and patient-specific optimal perfusion pressure.
Isolated congenital cholesteatoma of the middle ear
Isolated congenital cholesteatoma of the middle ear (ORPHA:686556, CCME, CMEC) is a rare epidermal cyst behind an intact eardrum, arising from embryonic epithelial rests, causing hearing loss or facial palsy, treated surgically.
Isolated ectopia lentis
Isolated ectopia lentis (familial ectopia lentis, ORPHA:1885) is a rare inherited eye disorder with lens dislocation and no systemic features, caused by FBN1 (dominant) or ADAMTSL4 (recessive) variants.
Isolated focal cortical dysplasia
Isolated focal cortical dysplasia (ORPHA:65683, epilepsy due to FCD) is a rare genetic cerebral malformation of neuronal migration causing drug-resistant epilepsy; ILAE types I and II, treated with resective surgery.
Isolated lymphatic malformation
Isolated lymphatic malformation (common cystic lymphatic malformation, ORPHA:458833) is a rare benign congenital malformation of lymphatic vessels causing cystic lesions, mostly in the head and neck, classified as macrocystic, microcystic, or mixed and treated with sclerotherapy, surgery, sirolimus, or alpelisib.
Isolated microspherophakia
Isolated microspherophakia is a rare eye disorder in which the crystalline lens is unusually small and spherical, typically in both eyes, causing high myopia, lens dislocation, and angle-closure glaucoma.
Isolated optic neuritis
Isolated optic neuritis (ION) is a rare inflammatory optic neuropathy with single or recurrent optic neuritis episodes unassociated with other neurological or systemic disease, presenting with subacute unilateral vision loss, eye-movement pain, and dyschromatopsia.
Isolated pulmonary artery sling
Isolated pulmonary artery sling (isolated anomalous left pulmonary artery, ORPHA 658574): the left pulmonary artery arises from the right and compresses the trachea, without associated cardiac or airway anomalies; treated by reimplantation.
Isolated right ventricular hypoplasia
Isolated right ventricular hypoplasia (IRVH, ORPHA:439, OMIM 277200) is a rare cyanotic congenital heart defect with an underdeveloped right ventricle, normally formed tricuspid and pulmonary valves, and usually a PFO or atrial septal defect causing right-to-left shunt.
Isolated spontaneous cervical artery dissection
Isolated spontaneous cervical artery dissection (CeAD, ORPHA:689001) is a rare non-traumatic tear of a neck artery wall causing false lumen and intramural hematoma; a major stroke cause in adults under 50, treated with antithrombotic therapy.
Isometric Contraction
Isometric contraction: muscle tension rises with no change in muscle length or joint angle, as in planks or pushing an immovable object; distinct from isotonic, concentric, and eccentric contractions.
Itch
Itch (pruritus) is an unpleasant skin sensation provoking scratching, defined by Hafenreffer in 1660. Carried by C fibers, relayed via spinal GRPR neurons; histaminergic and nonhistaminergic forms; chronic itch lasts 6+ weeks and resists antihistamines.
J comp neurol
J comp neurol abbreviates The Journal of Comparative Neurology (JCN), the oldest continually published basic neuroscience journal, founded 1891 by the Herrick brothers; Wiley-published systems neuroscience, print ISSN 0021-9967, edited by Suzana Herculano-Houzel.
J-shaped sella turcica
J-shaped sella turcica (omega-shaped or shoe-shaped sella), a J-shaped variant of the pituitary fossa on lateral skull imaging; a normal variant in 5-6% of children, also linked to mucopolysaccharidoses, achondroplasia, and optic chiasm glioma.
JACC: Cardiovascular Imaging
JACC: Cardiovascular Imaging (JACC Cardiovasc Imaging) is the American College of Cardiology's monthly peer-reviewed cardiac imaging journal, founded in 2008 under Jagat Narula, edited by Y.S. Chandrashekhar since 2017, with a 2025 impact factor of 19.0.
JACC: Cardiovascular Interventions
JACC: Cardiovascular Interventions (J Am Coll Cardiol Intv) is the American College of Cardiology's peer-reviewed interventional cardiology journal, launched 2008 under founding editor Spencer B. King III, publishing 24 issues yearly with a 2025 impact factor of 12.7.
Jahi McMath case
The Jahi McMath case is an American medicolegal dispute in which a 13-year-old girl, declared brain dead in Oakland in 2013, was kept on organ support for almost five years.
James L. Cox
James L. Cox (born 1942) is an American cardiothoracic surgeon, creator of the Cox maze procedure, the first surgical cure for atrial fibrillation, first performed in 1987 at Barnes Hospital, St. Louis; 2020 Jacobson Innovation Award recipient.
Jean Bennett
Jean Bennett, American physician-scientist at the University of Pennsylvania, co-developed Luxturna (voretigene neparvovec), the first FDA-approved gene therapy for an inherited disease, treating RPE65-linked blindness.
Jejunum
Jejunum: middle small intestine segment between duodenum and ileum, about 2.5 m and 40% of small bowel length; lacks Brunner's glands and Peyer's patches; main absorption site for carbohydrates, peptides, folate, calcium, magnesium.
Jervell and Lange-Nielsen syndrome
Jervell and Lange-Nielsen syndrome (JLNS), also called surdo-cardiac syndrome, is an autosomal recessive long QT syndrome with congenital deafness, caused by KCNQ1 or KCNE1 mutations, first described in Norway in 1957.
Jill Bolte Taylor
Jill Bolte Taylor, American neuroanatomist and author of My Stroke of Insight and Whole Brain Living; Harvard-trained, suffered a 1996 left-hemisphere stroke at 37 and recovered over eight years; her 2008 TED talk has over 30 million views.