2,701 articles
Primary tethered cord syndrome
Primary tethered cord syndrome (primary tethered spinal cord syndrome), a congenital low-lying, traction-fixed spinal cord with thickened filum terminale, causing progressive neurologic, musculoskeletal, and bladder/bowel symptoms; treated by surgical detethering.
Primitive reflexes
Primitive reflexes: involuntary brainstem-mediated motor responses (Moro, grasp, rooting, Galant, tonic neck) present from about 25 weeks of gestation, normally inhibited by 4-6 months, and clinically significant when absent, persistent, or reemergent.
Procainamide
Procainamide, a class IA sodium channel blocker and amide analog of procaine, treats life-threatening ventricular arrhythmias and stable VT; known for lupus-like syndrome, QT prolongation, and PROCAMIO trial superiority over amiodarone.
Proctalgia fugax
Proctalgia fugax is a functional anorectal pain disorder causing sudden, brief (seconds to 30 minutes) severe anal or rectal pain with symptom-free intervals, affecting roughly 3-18% of people, twice as often women; treated mainly with reassurance and warm sitz baths.
Prognosis of heart failure
Prognosis of heart failure is the estimation of a patient's future risk of death, hospitalization, or disease progression, based on clinical variables, biomarkers such as BNP, and validated risk scores.
Progressive bulbar palsy
Progressive bulbar palsy (PBP), also called progressive bulbar atrophy, is a motor neuron disease/ALS phenotype affecting lower brain stem cranial nerves, causing dysarthria, dysphagia, tongue and facial weakness, and fasciculations, usually progressing to widespread ALS.
Progressive muscular atrophy
Progressive muscular atrophy (PMA), also called the lower motor neuron variant of ALS, is a rare sporadic adult-onset motor neuron disease with pure LMN signs, slower course, TDP-43 pathology, and 22% later UMN conversion.
Progressive outer retinal necrosis
Progressive outer retinal necrosis (PORN), also called rapidly progressive herpetic retinal necrosis, is a VZV-caused viral retinitis of severely immunocompromised patients, mainly advanced AIDS, marked by minimal inflammation, rapid bilateral "cracked mud" retinal lesions, and poor vision outcomes.
Progressive pseudobulbar palsy
Progressive pseudobulbar palsy (ICD-11 8B60.2) is a motor neuron disease from bilateral corticobulbar tract degeneration, causing spastic dysarthria, dysphagia, and pseudobulbar affect without tongue wasting, distinct from progressive bulbar palsy.
Progressive supranuclear palsy
Progressive supranuclear palsy (PSP), or Steele-Richardson-Olszewski syndrome, is a rare 4-repeat tau neurodegenerative disease causing vertical gaze palsy, backward falls, and dementia, beginning around age 65 with severe disability within 3 to 5 years.
Prolactin
Prolactin (PRL), a 23 kDa polypeptide hormone from anterior pituitary lactotrophs, drives lactation and over 300 other actions; tonically inhibited by hypothalamic dopamine via D2 receptors; excess causes hyperprolactinemia, treated with dopamine agonists.
Proliferative diabetic retinopathy
Proliferative diabetic retinopathy (PDR), also called retinitis proliferans, is the advanced neovascular stage of diabetic retinopathy and a leading cause of working-age blindness; treated with panretinal photocoagulation, anti-VEGF injections, or vitrectomy.
Proliferative vitreoretinopathy
Proliferative vitreoretinopathy (PVR), also called massive periretinal proliferation, is a fibroproliferative complication of retinal detachment in which contractile membranes cause tractional redetachment; it affects 5–10% of RRD cases and has no approved drug therapy.
Pronation
Pronation: inward/downward rotation of the forearm (palm down, via pronator teres and quadratus) or of the foot (arch flattening during gait); opposite of supination, relevant to running shoes and injury.
Pronation of the foot
Pronation of the foot: triplanar motion (dorsiflexion, abduction, eversion) at the subtalar joint; also called overpronation when excessive. Evidence links pronated posture mainly to medial tibial stress syndrome and patellofemoral pain, with small effects.
Prone position
Prone position: lying face down, opposite of supine. Used surgically for posterior spine access and therapeutically in ARDS, where over 12 hours daily proning reduces mortality in severe cases.
Proprioception
Proprioception (Sherrington's term, 1906) is the body-position, movement, and force sense from muscle spindles, Golgi tendon organs, joint, and skin receptors; tested by TTDPM, JPR, AMEDA, and trainable for sport.
Prostate
Prostate: chestnut-sized male reproductive gland (~30 g) below the bladder, wrapping the urethra; secretes alkaline fluid making ~25% of semen. Zones (peripheral, central, transitional) explain BPH and cancer origins; PSA screening and MRI guide diagnosis.
Prothrombin G20210A
Prothrombin G20210A (20210G>A, c.97G>A, factor II mutation) is a common F2 gene variant raising prothrombin levels and venous clot risk; second most common inherited thrombophilia after factor V Leiden, autosomal dominant, mostly in European-descent populations.
Protruding ear
Protruding ear, also called prominent or bat ear, is a congenital auricular deformity with over 2 cm projection or auriculocephalic angle over 25 degrees, affecting about 5% of people, treated by infant ear molding or otoplasty.
Pseudocyst of spleen
Pseudocyst of spleen, also called secondary or false splenic cyst, is an epithelium-free fibrous-walled cyst, usually post-traumatic, accounting for 70-80% of nonparasitic splenic cysts and managed by spleen-preserving drainage or surgery.
Pseudostratified columnar epithelium
Pseudostratified columnar epithelium, also called respiratory epithelium when ciliated, is a single-layer tissue whose staggered nuclei mimic stratification; it lines the airways and male reproductive tract and drives mucociliary clearance.
Psoas major muscle
Psoas major: deep core muscle joining the iliacus as the iliopsoas, the thigh's primary flexor; inserts separately on the lesser trochanter and crosses the ~3 o'clock psoas valley of the acetabular rim.
Psychological research
Psychological Research is a peer-reviewed journal published by Springer, covering human perception, attention, memory, and action. Founded in 1922 as Psychologische Forschung, it became an English-language international journal in 1974.
Psychoneuroendocrinology
Psychoneuroendocrinology (PNE) is an interdisciplinary field linking psychology, endocrinology, immunology, neurology, and psychiatry, studying hormone-brain-behavior interactions; ISPNE founded 1975 with its journal Psychoneuroendocrinology.
Psychoneuroimmunology
Psychoneuroimmunology (PNI), also called psycho-neuro-immunology, studies bidirectional interactions among behavior, nervous and endocrine function, and immunity; founded on Ader and Cohen's 1975 conditioned immunosuppression, spanning stress effects on infection to inflammation in depression.
Pterygium
Pterygium (surfer's eye) is a benign wing-shaped fibrovascular growth of conjunctiva onto the cornea, driven by UV exposure, affecting about 8% of people globally, treated by excision with conjunctival autograft.
Pterygopalatine ganglion
Pterygopalatine ganglion, also called sphenopalatine or Meckel's ganglion, is the largest parasympathetic ganglion of the head, in the pterygopalatine fossa; facial nerve fibers synapse there to supply the lacrimal gland and nasal, palatal, and pharyngeal glands.
Ptosis (breasts)
Breast ptosis (breast sagging): descent of breast tissue and nipple-areola complex below the inframammary fold, graded I-III plus pseudoptosis by Regnault's 1976 classification; treated by mastopexy, with recurrence the main long-term issue.
Ptosis (eyelid)
Ptosis (blepharoptosis) is drooping of the upper eyelid margin, classified as aponeurotic, myogenic, neurogenic, or mechanical. Treated mainly by surgery; oxymetazoline 0.1% is the only FDA-approved drug for adults.