2,701 articles
Vestibular schwannoma
Vestibular schwannoma (acoustic neuroma) is a benign Schwann-cell tumor of the vestibulocochlear nerve causing unilateral hearing loss, tinnitus, and imbalance; managed by observation, radiosurgery, or microsurgery, with bilateral tumors signaling NF2.
Vestibular system
The vestibular system, or labyrinth, is the inner-ear sensory system detecting head motion and gravity via three semicircular canals and the utricle and saccule, enabling balance, gaze stabilization (VOR), and spatial orientation; disorders cause vertigo and imbalance.
Vestibulo–ocular reflex
Vestibulo–ocular reflex (VOR, oculovestibular reflex): automatic eye reflex stabilizing vision during head motion, gain normally 1, tested by head impulse, vHIT, caloric, and rotary chair tests.
Vestibulocochlear nerve
Vestibulocochlear nerve (CN VIII, acoustic nerve): purely sensory eighth cranial nerve carrying hearing from the cochlea and balance from the vestibular organs through the internal auditory canal to brainstem nuclei.
VGR-R01 (CYP4V2 AAV8 gene therapy)
VGR-R01 (rAAV2/8-CYP4V2) is Shanghai Vitalgen's subretinal AAV8 gene therapy delivering codon-optimized human CYP4V2 for Bietti crystalline dystrophy; phase 1/2 showed BCVA gains, phase 3 completed, NDA accepted by China CDE in June 2026.
Victor Chang
Victor Chang (Chang Yam Him, 1936–1991), Chinese-Australian cardiac surgeon who founded Australia's National Heart Transplant Program at St Vincent's Hospital, performed Fiona Coote's 1984 transplant, designed the low-cost St Vincent's Heart Valve, and was murdered in Sydney in 1991.
VICTORIA trial
VICTORIA (NCT02861534) was a phase 3 trial of vericiguat in 5,050 high-risk HFrEF patients, showing HR 0.90 for cardiovascular death or heart failure hospitalization versus placebo.
Viral conjunctivitis
Viral conjunctivitis (adenoviral pink eye) is a highly contagious acute conjunctival infection, usually adenovirus, causing red watery eyes; clinical diagnosis, supportive care, resolves in 7-14 days.
Viral retinitis
Viral retinitis: herpesvirus infection of the retina, mainly acute retinal necrosis (VZV, HSV), progressive outer retinal necrosis, and CMV retinitis in immunocompromised patients; necrotizing, retinal detachment-prone, treated with systemic and intravitreal antivirals.
Virilization
Virilization (masculinization, virilism): development of male secondary sexual characteristics in females or newborns from excess androgens, caused by CAH, Cushing syndrome, adrenal or ovarian tumors, or anabolic steroids; voice deepening is permanent.
Vision research
Vision Research (ISSN 0042-6989) is an Elsevier peer-reviewed journal of human, vertebrate, and invertebrate visual function, founded in 1961 in England, MEDLINE-indexed since 1964, publishing research, reviews, and special issues on vision.
Visual acuity
Visual acuity (VA): the eye's spatial resolving capacity, measured as the reciprocal of the minimum angle of resolution; 20/20 equals 1 arcmin. Tested with Snellen, Landolt C, and logMAR/ETDRS charts.
Visual Evoked Potentials
Visual evoked potentials (VEPs, visual evoked responses) are averaged EEG signals from the occipital cortex in response to pattern or flash stimuli, used clinically to assess optic nerve and visual pathway function, notably prolonged P100 latency in optic neuritis and multiple sclerosis.
Visual field
Visual field: the full area visible with fixed gaze, about 160 degrees horizontal per eye. Measured by perimetry (Goldmann, Humphrey SAP, kinetic, microperimetry); field defect patterns localize glaucoma and neurologic lesions.
Visual phototransduction
Visual phototransduction, also called the phototransduction cascade, is the process by which retinal rod and cone cells convert absorbed light into electrical responses via a G protein cascade.
Visual prosthesis
Visual prosthesis (bionic eye): implantable device restoring rudimentary sight by electrically stimulating surviving retinal or cortical neurons; approved devices include Argus II, IRIS II, Alpha IMS/AMS; acuity stays below legal blindness.
Visual system
Visual system: the neural pathway converting light into perception, from retinal phototransduction through optic nerve, chiasm, LGN, and visual cortex; also called the visual pathway, with retinotopic organization and localizable field defects.
Vital Capacity
Vital capacity (VC), including forced (FVC), slow (SVC), and inspiratory (IVC) variants, is the maximum air exhaled after a maximal inspiration, defined by John Hutchinson in 1846 and central to spirometric diagnosis of restrictive and obstructive lung disease.
Vitelline veins
Vitelline veins, or omphalomesenteric veins, are paired embryonic veins from the yolk sac to the sinus venosus; their selective involution forms the portal vein, splenic and mesenteric veins, and part of the inferior vena cava.
Vitrectomy
Vitrectomy is eye surgery removing vitreous gel to treat retinal diseases, such as detachment and macular holes; the procedure replaces the gel with saline, gas, or oil.
Vitreous body
Vitreous body (vitreous humor, corpus vitreum): transparent gel filling the eye between lens and retina, about 80% of ocular volume, 98-99.7% water with type II collagen and hyaluronan; develops in three phases and liquefies with age.
Vladimir Demikhov (Владимир Петрович Демихов)
Vladimir Petrovich Demikhov (Владимир Петрович Демихов, 1916–1998), Soviet experimental surgeon, pioneer of organ transplantology; first intrathoracic heart, lung, and heart-lung transplants in dogs, first mechanical heart, and the two-headed dog experiments.
Vocal cord paresis
Vocal cord paresis, or vocal fold paresis, is partial weakness of a vocal fold from incomplete laryngeal nerve denervation, between normal function and full paralysis; it causes glottic insufficiency, breathy voice, and is diagnosed with laryngoscopy plus laryngeal EMG.
Vocal cords
Vocal cords, commonly known as vocal folds, are muscularized tissue in the larynx. They vibrate with lung air to produce sound and protect the airway during swallowing.
Vollum Institute
The Vollum Institute, founded in 1987 and named for philanthropists Howard and Jean Vollum, is a privately endowed neuroscience research institute at Oregon Health & Science University in Portland, Oregon.
Volume expander
Volume expander: intravenous crystalloid or colloid fluids (albumin, gelatin, dextran, hydroxyethyl starch) used to restore intravascular volume in hypovolemia and shock; colloids expand more per liter but HES is now EU-suspended and FDA-boxed-warned.
Voretigene neparvovec
Voretigene neparvovec (Luxturna) is an AAV2-based gene therapy delivering the human RPE65 gene for biallelic RPE65 mutation-associated retinal dystrophy; FDA-approved December 19, 2017, EU-approved November 22, 2018, given by subretinal injection.
Voxel-based morphometry
Voxel-based morphometry (VBM) is an MRI neuroimaging method comparing gray matter voxel-wise between groups via normalization, segmentation, smoothing, and statistical parametric mapping; introduced by Ashburner and Friston (2000), distinct from surface-based morphometry.
VOYAGER PAD trial
VOYAGER PAD (NCT02504216) was a phase 3 trial of rivaroxaban 2.5 mg twice daily plus aspirin versus aspirin alone after lower-extremity revascularization in 6,564 PAD patients, reducing the composite limb and cardiovascular endpoint (HR 0.85) without significant TIMI major bleeding excess.
VRandMRI study
VRandMRI (NCT05098587) is a completed observational pilot study by Swiss Paraplegic Research, Nottwil, testing whether Virtual Walk therapy changes pain perception, BOLD fMRI activity, and MRS metabolites in 12 SCI patients with neuropathic pain.