25,729 articles
Paramethasone acetate
Paramethasone acetate (Haldrone, Monocortin; CAS 1597-82-6) is a synthetic fluorinated glucocorticoid, the 21-acetate of paramethasone, about 10 times as potent as hydrocortisone with no mineralocorticoid activity; its US oral tablets are discontinued.
Parametric magnetic resonance imaging
Parametric magnetic resonance imaging is a medical imaging approach that maps relaxation times such as T1, T2, and T2 pixel by pixel in absolute units, detecting diffuse disease conventional MRI misses.
Paramyotonia congenita of Von Eulenburg
Paramyotonia congenita of Von Eulenburg (Eulenburg disease, PMC) is a rare autosomal dominant SCN4A sodium channelopathy causing cold- and exercise-worsened myotonia with episodic weakness, distinct from chloride-channel myotonia congenita.
Paranasal sinuses
Paranasal sinuses: air-filled mucosa-lined cavities in the frontal, ethmoid, maxillary, and sphenoid bones communicating with the nasal cavity; function debated, distribution ecologically shaped, prone to sinusitis.
Paraneoplastic cerebellar degeneration
Paraneoplastic cerebellar degeneration (PCD), or paraneoplastic cerebellar ataxia, is tumor-induced autoimmune Purkinje cell loss causing subacute ataxia, mainly anti-Yo antibody with breast and gynecologic cancers, with poor prognosis.
Paraneoplastic pemphigus
Paraneoplastic pemphigus (PNP), or paraneoplastic autoimmune multiorgan syndrome (PAMS), is a rare, often fatal autoimmune blistering disease with severe stomatitis and polymorphous skin lesions, caused by anti-plakin autoantibodies and associated with lymphoma, chronic lymphocytic leukemia, and Castleman disease.
Paraneoplastic polymyositis
Paraneoplastic polymyositis (ICD-11 4A41.11) is polymyositis occurring as an immune-mediated remote effect of cancer. Cancer risk is mildly increased (OR 2.1), mostly lymphoma, lung, and bladder cancers within a year of myositis onset.
Paraneoplastic sensory ganglionopathy
Paraneoplastic sensory ganglionopathy (paraneoplastic sensory neuronopathy, Denny-Brown syndrome): immune-mediated dorsal root ganglion neuron loss from cancer, usually anti-Hu antibodies with small-cell lung cancer, causing subacute asymmetric sensory loss, ataxia, and pain without weakness.
Paraneoplastic syndrome
Paraneoplastic syndrome: remote effects of cancer, also called PNS, caused by tumor-secreted hormones or cross-reactive immune responses, affecting endocrine, neurologic, cutaneous, hematologic, and other systems, often preceding cancer diagnosis.
Paraneoplastic uveitis
Paraneoplastic uveitis is intraocular inflammation caused by an immune response to systemic malignancy rather than tumor invasion, often anti-CRMP-5-associated, mimicking VKH-like or sarcoid-like uveitis and frequently preceding cancer diagnosis.
Paranoia
Paranoia is persecutory ideation, the belief of intentional harm from others, spanning subclinical mistrust to persecutory delusions; 10-15% of people have paranoid thoughts, and experimental paradigms induce it with a medium effect (g = 0.51).
Paranoid ideation
Paranoid ideation (ICD-11 MB26.7) is suspiciousness or beliefs of being persecuted or unfairly treated, held below delusional intensity; distinct from persecutory delusion, common in the general population, and measured by the R-GPTS.
Paranoid personality disorder
Paranoid personality disorder (PPD), ICD-10 F60.0, a Cluster A personality disorder of pervasive unwarranted distrust and suspicion without delusions or hallucinations; prevalence about 3.2%, treated with CBT, no proved effective treatment.
Paraparetic variant of Guillain-Barré syndrome
The paraparetic variant of Guillain-Barré syndrome is a rare GBS form in which leg weakness and areflexia spare the arms, cranial nerves, and respiratory muscles.
Paraphilia
Paraphilia: intense, persistent atypical sexual interest; a paraphilic disorder only when distressing, impairing, or harmful. DSM-5/ICD-11 distinction, history from Krafft-Ebing, critiques, and treatment.
Paraphilic disorder
Paraphilic disorder: DSM-5/ICD-11 diagnosis in which an atypical sexual interest (paraphilia) causes distress, impairment, or harm to nonconsenting others; eight specific types, forensic use, and treatment.
Paraphimosis
Paraphimosis: urologic emergency in which the retracted foreskin is trapped behind the glans corona, causing edema and ischemia; distinct from phimosis; treated by manual reduction, osmotic agents, or dorsal slit.
Paraplegia
Paraplegia is paralysis of the lower body and both legs with preserved arm function, usually from spinal cord injury below the neck; also called paraplegic paralysis, distinct from quadriplegia or tetraplegia.
Paraquat poisoning
Paraquat poisoning: toxic injury from the herbicide paraquat dichloride (methyl viologen, Gramoxone), usually from ingestion; no antidote, lung accumulation 6-10x plasma, hemoperfusion OR 0.20, EU ban 2007.
Parasite Egg Count
A parasite egg count is a laboratory measurement of parasite eggs per gram of feces, estimating helminth infection intensity in humans and animals and guiding public-health deworming programs.
Parasitic Sensitivity Tests
Parasitic sensitivity tests (MeSH D021261) measure the effectiveness of drugs against parasites, chiefly in vitro and ex vivo malaria IC50 and ring-stage survival assays supporting antimalarial resistance surveillance.
Parasitic twin
Parasitic twin (heteropagus, fetus in fetu, acardiac twin): a malformed conjoined twin dependent on a dominant twin's circulation, affecting under 1 in 1 million births, treated by surgery on the host.
Parasomnia
Parasomnia: abnormal behaviors or experiences during sleep, sleep onset, or waking, including sleepwalking, night terrors, sleep paralysis, and REM sleep behavior disorder; classified as NREM, REM, or other parasomnias.
Paraspinal arteriovenous malformation
Paraspinal arteriovenous malformation (paraspinal arteriovenous shunt, PAVS): a rare artery-vein shunt outside the spinal canal, classified by the Stuttgart scheme as isolated or genetically associated, usually treated by endovascular embolization.
Paraspinal neuroblastoma
Paraspinal neuroblastoma: neuroblastoma arising in sympathetic ganglia alongside the spine from neck to pelvis, prone to dumbbell intraspinal extension, cord compression, and emergent chemotherapy.
Parastomal hernia
Parastomal hernia (PSH): an incisional hernia at a colostomy, ileostomy, or ileal conduit stoma site; incidence 28–48%, risk factors include BMI, age, female sex, aperture size; mesh repair preferred over suture repair.
Parastomal hernia repair
Parastomal hernia repair is a surgical procedure correcting herniation of abdominal contents through the fascial defect around an intestinal stoma, most often with mesh reinforcement, performed open, laparoscopically, or robotically.
Parasympathectomy
Parasympathectomy is surgical removal or interruption of part of the parasympathetic nervous system, chiefly vagotomy for peptic ulcer (truncal, selective, highly selective), introduced by Dragstedt in 1943 and now largely superseded by drug therapy.
Parasympathetic nervous system
Parasympathetic nervous system, the craniosacral division of the autonomic nervous system coined by Langley. Outflow via cranial nerves III, VII, IX, X and S2–S4; long preganglionic fibers, acetylcholine, ganglia near target organs, rest-and-digest function.
Parasympathetic neuron
Parasympathetic neuron: cholinergic motor neuron of the parasympathetic (craniosacral) autonomic division; preganglionic cells in brainstem nuclei and S2–S4, postganglionic cells in ganglia near target organs, vagus carrying 75% of fibers.