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Intracranial aneurysm
Intracranial (cerebral, brain) aneurysm: localized dilation of a brain artery; rupture causes subarachnoid hemorrhage. Treated by microsurgical clipping (first done by Dandy, 1937) or endovascular coiling (GDC, 1991).
Intracranial electroencephalography
Intracranial electroencephalography (iEEG) records brain electrical activity from electrodes inside the skull, either on the cortical surface (ECoG) or within the brain (SEEG), to localize seizure onset before surgery for drug-resistant epilepsy.
Intracranial granuloma
Intracranial granuloma (ICD-11 1D04.1) is a focal intracranial mass of macrophages and giant cells caused by infection (tuberculoma, fungal, parasitic), sarcoidosis, or foreign material; diagnosed by CT/MRI and biopsy.
Intracranial hemorrhage
Intracranial hemorrhage, also called intracerebral or subarachnoid hemorrhage, is bleeding inside the skull. It causes 10-20% of strokes, has 30-40% early mortality, and is treated per the 2022 AHA/ASA guideline.
Intracranial hypotension
Intracranial hypotension, also called spontaneous intracranial hypotension (SIH) or CSF hypovolemia, is low CSF volume from a spinal leak causing orthostatic headache; incidence 3.7/100,000, treated with epidural blood patch or surgery.
Intracranial pressure
Intracranial pressure (ICP), also called intracranial hypertension when elevated, is the pressure inside the rigid skull from brain, blood, and CSF. Normal 7–15 mm Hg; above 20–25 mm Hg pathological, treated with osmotherapy, drainage, or craniectomy.
Intracranial recording
Intracranial recording, also called intracranial EEG or iEEG, measures electrical activity directly from electrodes inside the skull or brain, chiefly to localize seizure onset in drug-resistant epilepsy.
Intracranial space-occupying lesion
Intracranial space-occupying lesion (ICD-11 MB71.0, ICD-10-CM R90.0), also called intracranial mass lesion: any discrete intracranial lesion causing mass effect, mainly tumor, hemorrhage, abscess, or infarction, evaluated chiefly by contrast-enhanced MRI.
Intracranial vascular malformation
Intracranial vascular malformation (ICD-11 8B22.4): abnormal brain blood vessels including AVMs, dural fistulas, cavernous malformations, venous anomalies, and telangiectasias, differing in hemorrhage risk and treatment.
Intradermal injection
Intradermal injection delivers a small volume of drug or vaccine into the dermis, used for tuberculin and allergy skin tests and for dose-sparing vaccination against rabies, influenza, and mpox.
Intradermal test
An intradermal test is a diagnostic skin test that injects allergen or antigen into the dermis, detecting immediate IgE-mediated or delayed hypersensitivity, used in allergy workup and tuberculosis screening.
Intraductal papillary mucinous carcinoma of pancreas
Intraductal papillary mucinous carcinoma of pancreas (IPMN with associated invasive carcinoma) is a rare malignant mucin-producing ductal tumor. Prognosis depends on histologic subtype: pancreatobiliary/tubular worst, colloid better; 5-year survival about 31% after resection.
Intraductal papilloma of breast
Intraductal papilloma of breast (intraductal breast papilloma): benign wart-like growth in a milk duct, ages 35-55, causing nipple discharge. Solitary form does not raise cancer risk; multiple papillomas may; upgrade to carcinoma 5% benign, 36% atypical.
Intraductal tubulopapillary neoplasm of pancreas
Intraductal tubulopapillary neoplasm (ITPN) of the pancreas, also called intraductal tubule-papillary neoplasm, is a rare non-mucinous intraductal pancreatic tumor with high-grade dysplasia, MUC1/MUC6 positivity, invasive component in about 60%, and favorable post-surgical survival.
Intraepidermal squamous cell carcinoma
Intraepidermal squamous cell carcinoma, also called Bowen's disease or squamous cell carcinoma in situ, is a noninvasive skin cancer confined to the epidermis, with about 3% progression risk and treatments including 5-FU, PDT, cryotherapy, and excision.
Intrafusal muscle fiber
Intrafusal muscle fiber: the small stretch-sensing fibers inside muscle spindles, in three types (bag1, bag2, chain), innervated by Ia/II afferents and dynamic/static gamma motoneurons for proprioception.
Intragastric administration
Intragastric administration is a drug delivery method in which a compound is introduced directly into the stomach of a laboratory rodent, most commonly by gavage, a feeding tube passed through the mouth.
Intrahepatic cholangiocarcinoma
Intrahepatic cholangiocarcinoma (iCCA, ICC) is the second most common primary liver cancer after HCC, arising proximal to second-order bile ducts; surgery is the only cure, with FGFR2/IDH1 targeted therapies for advanced disease.
Intrahepatic cholestasis of pregnancy
Intrahepatic cholestasis of pregnancy (obstetric cholestasis, ICP): pregnancy-specific liver disorder with pruritus and raised serum bile acids in late pregnancy. Graded mild 19–39, moderate 40–99, severe ≥100 µmol/L; UDCA and delivery timing vary by guideline.
Intralesional Infusions
Intralesional infusions (MeSH: Infusions, Intralesional) deliver medication directly into localized lesions via gravity flow or infusion pumps, distinct from intralesional injections; used in melanoma (T-VEC, PV-10), keloids, and skin disease.
Intralesional injection
An intralesional injection delivers medication directly into a skin lesion or other diseased tissue rather than the circulation, most often triamcinolone, a mainstay treatment for keloid scars and warts.
Intralymphatic Injections
Intralymphatic injections deliver drugs or allergens directly into lymph nodes or lymphatic vessels (endolymphatic injection). Main use is intralymphatic immunotherapy (ILIT), three ultrasound-guided node injections replacing years of allergy shots, plus experimental cancer vaccine delivery.
Intramedullary nail fixation
Intramedullary nail fixation is a surgical technique that stabilizes long-bone fractures with a metal rod in the marrow canal, the standard for femoral and tibial shaft fractures.
Intramedullary nailing
Intramedullary nailing is a surgical technique for fixing long-bone fractures in which a metal rod is inserted into the marrow canal and secured with locking screws.
Intramedullary screw fixation
Intramedullary screw fixation is an orthopedic technique that stabilizes unstable metacarpal and phalangeal fractures of the hand with a headless compression screw placed in the bone's medullary canal.
Intramuscular fast-flow vascular anomaly
Intramuscular fast-flow vascular anomaly (IM-FFVA), formerly intramuscular capillary-type hemangioma, is a rare fast-flow lesion within skeletal muscle carrying somatic MAP2K1 or KRAS mutations, treated mainly by complete surgical resection.
Intramuscular injection
An intramuscular injection delivers medication deep into a muscle, bypassing liver metabolism and absorbing faster than subcutaneous routes; common sites are the deltoid and thigh.
Intranasal administration
Intranasal administration is a drug delivery route giving medication through the nose as a spray, drops, gel, or powder, offering rapid onset that avoids hepatic first-pass metabolism.
Intraocular administration
Intraocular administration is a drug delivery route in which medication is injected directly into compartments of the eye, most commonly the vitreous cavity, to treat retinal disease.
Intraocular injection
Intraocular injection is a clinical procedure that delivers a drug directly into the eye to treat retinal diseases, minimizing systemic absorption; intravitreal injection is the most common form.