Human health and medicine

Functional heartburn

Functional heartburn (FH): retrosternal burning with normal acid exposure, endoscopy, and manometry, a Rome IV gut-brain disorder distinct from GERD and reflux hypersensitivity; PPIs fail, neuromodulators help.

Functional Independence Measure

The Functional Independence Measure (FIM) is an 18-item rating scale used in rehabilitation medicine to quantify the assistance a person with a disability needs for daily activities.

Functional lumen imaging probe

The functional lumen imaging probe (FLIP), marketed as EndoFLIP, is an endoscopic catheter that measures luminal distensibility during balloon distention, used to assess the esophagogastric junction and pylorus.

Functional luminal imaging

Functional luminal imaging (FLIP) is an endoscopic technique that measures the size and compliance of a distended gastrointestinal lumen by impedance planimetry, used mainly to assess the esophagogastric junction in motility and reflux disease.

Functional magnetic resonance imaging

Functional magnetic resonance imaging (fMRI), including BOLD task fMRI and resting-state fMRI, noninvasively maps brain activity via blood oxygenation; developed from Ogawa's 1990 BOLD discovery, used clinically for presurgical planning, with known poor task-fMRI test-retest reliability (mean ICC .397).

Functional medicine

Functional medicine: a root-cause, systems biology care model from Jeffrey Bland and the Institute for Functional Medicine (IFM), featuring extended history-taking, nonstandard lab panels, supplement protocols, certification (FMCP-M), mixed evidence, and direct-pay costs.

Functional near-infrared spectroscopy

Functional near-infrared spectroscopy (fNIRS), also called optical topography or diffuse optical imaging, is a portable, non-invasive neuroimaging method using 650–950 nm light to measure cortical HbO/HbR hemodynamic changes; first human studies 1991/1992, standardized by IEC 80601-2-71:2025.

Functional neuroimaging

Functional neuroimaging measures human brain activity via fMRI, PET, MEG, EEG, and fNIRS, either hemodynamically (millimeter spatial, seconds temporal) or electromagnetically (millisecond temporal), with clinical use in presurgical brain mapping.

Functional Orthodontic Appliances

Functional orthodontic appliances (activator, Herbst, Twin Block, Frankel regulator) are removable or fixed devices that correct Class II malocclusion by posturing the mandible forward, using muscle forces to modify jaw growth in children.

Functional parkinsonism

Functional parkinsonism (FP), ICD-11 8A00.3, is a parkinsonian syndrome caused by functional neurological disorder, not dopamine degeneration; tremor, rigidity, and slowness show distractibility, entrainment, and no true bradykinesia.

Functional reach test

The functional reach test is a clinical balance assessment that measures the difference between arm's length and maximal forward reach with feet fixed, screening postural stability and fall risk.

Functional Residual Capacity

Functional residual capacity (FRC): lung gas volume after normal passive exhalation, ERV plus RV, about 3 L normally. Measured by plethysmography, helium dilution, or nitrogen washout, not spirometry; rises in obstruction, falls in obesity and anesthesia.

Functional respiratory imaging

Functional respiratory imaging (FRI) is a computational method combining high-resolution lung CT scans with computational fluid dynamics to quantify regional ventilation and airway resistance in respiratory disease.

Functional Status

Functional status is a health outcome describing how well a person can perform everyday tasks, from walking and concentrating to self-care activities like bathing, dressing, and eating.

Functional tremor

Functional tremor (psychogenic tremor), the most common functional movement disorder, is involuntary-appearing tremor with variability, distractibility, and entrainment; diagnosed clinically and electrophysiologically, treated with physiotherapy and CBT.

Functional ultrasound imaging

Functional ultrasound imaging (fUS, also fUSI) is a neuroimaging method that uses high-frame-rate ultrasound to measure cerebral blood volume changes, applied in rodents, primates, and humans.

Functional urinary incontinence

Functional urinary incontinence (FUI, toileting difficulty, ICD-11 MF50.23; ICS: disability associated incontinence): urine loss from cognitive or physical impairment blocking toilet access, not bladder disease; common in nursing homes, managed with prompted voiding and environmental change.

Functioning gonadotropic adenoma

Functioning gonadotropic adenoma, also called functioning gonadotroph adenoma (FGA), is a rare benign pituitary tumor secreting active FSH or LH, causing ovarian hyperstimulation in women and testicular enlargement in men.

Fundal height

Fundal height (symphysis-fundal height, SFH) is the tape-measured distance from the pubic bone to the top of the uterus, used after 24 weeks to screen fetal growth; roughly 1 cm per gestational week, with limited sensitivity.

Fundoplication

Fundoplication is an operation in which the upper stomach is wrapped around the lower esophagus to reinforce the sphincter against reflux, the main surgery for GERD and hiatal hernia.

Fundus albipunctatus

Fundus albipunctatus (OMIM 136880) is a rare autosomal recessive congenital stationary night blindness with white midperipheral retinal dots and delayed dark adaptation, usually caused by RDH5 mutations; distinct from progressive retinitis punctata albescens.

Fundus autofluorescence imaging

Fundus autofluorescence (FAF) imaging is a noninvasive ophthalmic technique recording the fundus's natural fluorescence, used to assess retinal health in macular degeneration and inherited retinal dystrophies.

Fundus fluorescein angiography

Fundus fluorescein angiography (FFA) is an ophthalmic imaging method that injects sodium fluorescein intravenously and photographs the retina over time to visualize blood flow, capillary perfusion, and barrier leakage.

Fundus photography

Fundus photography is an ophthalmic imaging method that uses a fundus camera to photograph the retina, optic nerve, and macula, detecting diabetic retinopathy, glaucoma, and macular degeneration.

Fundus pulverulentus

Fundus pulverulentus is the rarest pattern dystrophy of the retinal pigment epithelium, first described by Slezak and Homer in 1969, marked by granular coarse RPE mottling of the macula, strong pseudoxanthoma elasticum association, and reported choroidal neovascularization.