72,234 articles
Functional anorectal disorders
Functional anorectal disorders are chronic anorectal conditions not explained by structural disease, defined by the Rome IV criteria and classified as fecal incontinence, anorectal pain, and functional defecation disorders.
Functional anorectal pain
Functional anorectal pain (ICD-11 DD92.1) is pain of the rectum or anus without structural cause, classified by Rome IV as levator ani syndrome, unspecified functional anorectal pain, or proctalgia fugax.
Functional connectivity analysis
Functional connectivity analysis measures statistical relationships, most commonly temporal correlations, between activity in different brain regions, typically from resting-state fMRI, and is used in clinical research on brain disorders.
Functional connectivity MRI
Functional connectivity MRI, also called resting-state fMRI, is an MRI method that maps brain networks by measuring correlations of spontaneous BOLD signal fluctuations between regions, without any task or stimulus.
Functional defaecation disorders
Functional defaecation disorders (FDDs, Rome IV category F3; ICD-11 DD92.2) are gut-brain interaction disorders with impaired rectal evacuation, subtypes inadequate defecatory propulsion and dyssynergic defecation, diagnosed by 2 of 3 physiological tests and treated with biofeedback.
Functional diarrhoea
Functional diarrhoea (FDr, ICD-11 DD91.2) is a gut-brain disorder of chronic loose or watery stools in over 25% of stools without predominant abdominal pain, distinguished from IBS-D and diagnosed with limited testing.
Functional dyspepsia
Functional dyspepsia (FD) is a gut-brain interaction disorder causing recurrent upper abdominal symptoms without structural disease, affecting 5-10% of people, diagnosed by Rome criteria, with subtypes PDS and EPS and treatments including TCAs and prokinetics.
Functional electrical stimulation
Functional electrical stimulation (FES) applies electrical pulses to intact peripheral motor nerves to produce coordinated muscle contractions for useful movements such as walking, grasping, or cycling, used in spinal cord injury and stroke.
Functional family therapy
Functional family therapy (FFT) is a short-term, family-based treatment for adolescents with behavioral problems such as delinquency and substance use, developed at the University of Utah in 1969.
Functional Food
Functional food: foods offering health benefits beyond basic nutrition, also called nutraceuticals or designer foods. No legal definition in EU or US; concept from Japan's 1984 project and FOSHU system; regulated via health-claim frameworks.
Functional gallbladder disorder
Functional gallbladder disorder, also called biliary dyskinesia or chronic acalculous cholecystitis, is biliary pain without gallstones or structural pathology, diagnosed by Rome IV criteria and HIDA ejection fraction, and often treated with cholecystectomy of uncertain benefit.
Functional gastrointestinal disorder
Functional gastrointestinal disorder (FGID), now disorders of gut-brain interaction (DGBI), chronic GI symptom syndromes diagnosed by Rome criteria; over 40% global prevalence, renamed by Rome IV 2016, Rome V 2026.
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.
Functional–structural plant model
A functional–structural plant model (FSPM) is a simulation that couples a plant's three-dimensional architecture with physiological processes to predict growth of individual plants under defined environmental conditions.