1,527 articles
Pineal parenchymal tumor of intermediate differentiation
Pineal parenchymal tumor of intermediate differentiation (PPTID) is a rare WHO grade 2 or 3 brain tumor arising from the pineal gland, intermediate between pineocytoma and pineoblastoma.
Pineoblastoma
Pineoblastoma is a fast-growing, CNS WHO grade 4 malignant embryonal brain tumor of the pineal gland, mainly in young children. Four molecular subtypes (miRNA-altered, MYC/FOXR2, RB1) determine prognosis; treatment combines surgery, radiation, and chemotherapy.
Pineocytoma
Pineocytoma, also called pinealocytoma, is a WHO grade 1, slow-growing, well-differentiated tumor of pineal gland parenchymal cells in adults, with 86-91% five-year survival, rare CSF spread, and excellent prognosis after complete resection.
Pituicytoma
Pituicytoma, also called granular/oncocytic/ependymal pituicytoma in WHO 2022 grouping, is a rare low-grade TTF-1-positive glial tumor of pituicytes of the posterior pituitary, causing visual loss, headache, and hypopituitarism; cured by resection.
PLA2G6-related neurodegeneration, adult-onset
Adult-onset PLA2G6-related neurodegeneration (PARK14, adult PLAN) is a rare autosomal recessive dystonia-parkinsonism disorder from PLA2G6 mutations on 22q13.1, with levodopa-responsive parkinsonism, dyskinesias, and cognitive decline.
PLA2G6-related neurodegeneration, infantile-onset
Infantile-onset PLA2G6-related neurodegeneration (infantile neuroaxonal dystrophy, INAD, NBIA2A) is a rare autosomal recessive NBIA disorder from PLA2G6 mutations at 22q13.1, causing psychomotor regression, hypotonia, spastic tetraparesis, cerebellar atrophy, and death usually within about ten years.
PLA2G6-related neurodegeneration, juvenile-onset
Juvenile-onset PLA2G6-related neurodegeneration (juvenile PLAN, formerly atypical neuroaxonal dystrophy, ORPHA:728432) is an autosomal recessive NBIA disorder caused by PLA2G6 variants, with childhood or adolescent onset, ataxia, dystonia, visual loss, and slower progression than infantile PLAN.
Plateau iris syndrome
Plateau iris syndrome (PIS): angle closure persisting after patent laser iridotomy, caused by an anteriorly positioned ciliary body pushing the iris root into the trabecular meshwork; distinct from plateau iris configuration, treated with iridoplasty.
Pleomorphic xanthoastrocytoma
Pleomorphic xanthoastrocytoma (PXA), a rare BRAF V600E-driven astrocytic brain tumor of children and young adults, WHO grade 2 or 3, usually temporal lobe, treated by resection.
Pneumococcal meningitis
Pneumococcal meningitis, bacterial meningitis caused by Streptococcus pneumoniae (pneumococcus); leading cause of bacterial meningitis in Europe and the US, with 16-37% mortality, treated with ceftriaxone plus dexamethasone and prevented by conjugate vaccines.
Polyhydramnios-megalencephaly-symptomatic epilepsy syndrome
PMSE syndrome, also called Pretzel syndrome, is an ultra-rare autosomal recessive neurodevelopmental disorder caused by homozygous STRADA (LYK5) loss on 17q23.3, causing polyhydramnios, infantile intractable epilepsy, megalencephaly, and mTOR hyperactivation.
Polyneuropathy
Polyneuropathy is simultaneous dysfunction of many peripheral nerves, mainly length-dependent and axonal, most often from diabetes (~206 million affected). Distinguish from mononeuropathy; CIDP, small-fiber, and toxic subtypes differ in tests and treatment.
Polyneuropathy associated with IgM monoclonal gammopathy
Polyneuropathy associated with IgM monoclonal gammopathy is a rare disorder in which a monoclonal IgM protein, often anti-MAG, causes slowly progressive numbness and unsteadiness in the legs.
Polyneuropathy-hearing loss-ataxia-retinitis pigmentosa-cataract syndrome
PHARC syndrome (MIM 612674, ORPHA171848), also called peripheral neuropathy Fiskerstrand type, is a rare autosomal recessive neurodegenerative disease caused by ABHD12 mutations, combining demyelinating polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and early-onset cataract.
Pontine autosomal dominant microangiopathy with leukoencephalopathy
PADMAL (pontine autosomal dominant microangiopathy with leukoencephalopathy), also called autosomal dominant pontine microangiopathy, is a rare COL4A1 3'UTR cerebral small vessel disease causing recurrent pontine ischemic strokes and dementia from the thirties or forties, distinct from CADASIL.
Pontine tegmental cap dysplasia
Pontine tegmental cap dysplasia (PTCD) is a rare sporadic hindbrain malformation with a flattened ventral pons, a tegmental cap protruding into the fourth ventricle, sensorineural deafness, cranial nerve deficits, and developmental delay; first named by Barth et al. in 2007.
Pontocerebellar hypoplasia
Pontocerebellar hypoplasia (PCH), also called pontoneocerebellar hypoplasia, is a group of rare autosomal recessive neurodegenerative disorders with prenatal onset affecting the pons and cerebellum; 17 types and 25 genes are recognized, first described in 1912.
Porencephaly
Porencephaly is a rare brain malformation with fluid-filled intracerebral cavities, genetic (COL4A1/COL4A2, autosomal dominant) or acquired from hemorrhage, ischemia, or injury, causing seizures, hemiparesis, and developmental delay.
Post traumatic Parkinsonism
Post-traumatic parkinsonism (PTP), ICD-11 8A00.25, is a rare secondary parkinsonism after traumatic brain injury, with bradykinesia, rigidity, and tremor, typically 1–6 months post-injury, mostly in males, and responsive to levodopa or decompressive surgery.
Posterior cerebral artery syndrome
Posterior cerebral artery syndrome: deficits from infarction in the PCA territory (occipital, temporal lobes, thalamus, midbrain), causing homonymous hemianopia, sensory and neuropsychological deficits, mostly from embolism.
Posterior column ataxia-retinitis pigmentosa syndrome
Posterior column ataxia-retinitis pigmentosa syndrome (PCARP, OMIM 609033) is an autosomal recessive FLVCR1-related disorder with childhood-onset sensory ataxia from spinal posterior column degeneration and retinitis pigmentosa leading to blindness; about 20 cases reported.
Posterior cortical atrophy
Posterior cortical atrophy (Benson's syndrome) is a rare young-onset dementia syndrome of visuospatial and perceptual decline from parieto-occipital atrophy, usually caused by Alzheimer's disease pathology.
Posterior ischemic optic neuropathy
Posterior ischemic optic neuropathy (PION), also called retrobulbar ischemic optic neuropathy, is sudden painless vision loss from ischemia of the posterior optic nerve with a normal initial fundus. Three subtypes: non-arteritic, arteritic (giant cell arteritis), and perioperative, most often after spine surgery.
Posterior polymorphous corneal dystrophy
Posterior polymorphous corneal dystrophy (PPCD, Schlichting dystrophy) is a rare autosomal dominant corneal endothelial dystrophy with vesicular, band-like, and diffuse Descemet membrane opacities, subtypes PPCD1-4 linked to OVOL2, COL8A2, ZEB1, and GRHL2, and variable severity from asymptomatic to glaucoma and corneal edema.
Postherpetic neuralgia
Postherpetic polyneuropathy (ICD-11 1E91.5), also called postherpetic neuralgia, is chronic dermatomal neuropathic pain after shingles, caused by VZV reactivation damaging sensory nerves; affects 5–30% of zoster patients, mostly elderly.
Postictal state
The postictal state, also called the postictal phase, is the temporary period of confusion and other symptoms that follows an epileptic seizure, lasting minutes to days.
Postinfectious cerebellitis
Postinfectious cerebellitis (acute postinfectious cerebellar ataxia, PIC, ORPHA:624244) is an immune-mediated cerebellar inflammation after infection, mainly varicella in children and EBV or mycoplasma in adults, causing acute ataxia that usually resolves fully.
Postpoliomyelitis syndrome
Postpoliomyelitis syndrome (PPS, post-polio syndrome): new weakness, fatigue, and pain appearing 15-30 years after recovery from paralytic polio, affecting 20-85% of survivors; a clinical diagnosis of exclusion with no specific drug treatment.
Posttransplant acute limbic encephalitis
Posttransplant acute limbic encephalitis (PALE) is a rare non-paraneoplastic limbic encephalitis after allogeneic HSCT, causing amnesia, confusion, and seizures 2-6 weeks post-transplant, usually linked to HHV-6.
Pre-Descemet corneal dystrophy
Pre-Descemet corneal dystrophy (PDCD), including punctiform and polychromatic PPPCD, is a rare inherited stromal corneal dystrophy with deep stromal opacities anterior to Descemet membrane, asymptomatic, PRDX3-linked, good prognosis.