Ortner syndrome, also known as cardiovocal syndrome, is characterized by hoarse voice resulting from left recurrent laryngeal nerve palsy secondary to a cardiovascular disorder.
Left recurrent laryngeal nerve palsy in this condition is due to traction or compression of the nerve betw...
Osmotic demyelination syndrome refers to acute demyelination seen in the setting of osmotic changes, typically with the rapid correction of hyponatremia. It is the more recent term replacing central pontine myelinolysis, recognizing that extrapontine structures can also be affected, previously k...
Osteopathia striata with cranial sclerosis (OS-CS) is a clinically separate entity from osteopathia striata (Voorhoeve disease). Bony changes on their own are typically incidental and autosomal dominant, whereas OS-CS is a multisystem, X-linked dominant disorder.
OS-CS is extremel...
Osteoporosis pseudoglioma syndrome is a rare autosomal recessive disease that is characterized by severe osteoporosis and blindness. This disease is frequently mistaken for osteogenesis imperfecta.
This disease is encountered in approximately 1 in 2 million births.
Otopalatodigital syndrome type I is a rare genetic disorder marked by the association of
and a characteristic face (with hypertelorism, broad nasal root, prominent supraorbital ridges, small flat nose and downslanted palpebral fissures).
It is ...
Ovarian hyperstimulation syndrome (OHSS) is a complication of ovarian stimulation treatment (ovarian induction therapy) for in vitro fertilisation. Rarely, it may also occur as a spontaneous event in pregnancy (see spontaneous ovarian hyperstimulation later in the article).
The clinical syndrom...
Ovarian vein syndrome is a relatively rare condition where a dilated ovarian vein (ovarian venous varix) causes notching, dilatation, or obstruction of the ureter. This is usually secondary to varicoses of the ovarian vein or ovarian vein thrombosis and occurs at the point where the ovarian vein...
Paget-Schrötter syndrome, alternatively spelled Paget-Schroetter syndrome and also known as effort thrombosis, refers to primary thrombosis of the axillary and/or subclavian vein. It can be thought of as a venous equivalent of thoracic outlet syndrome.
It is associated with forced...
Pallister-Hall syndrome displays a wide range of severity and is characterized by hypothalamic hamartomas seen as a mass at the floor of the third ventricle, posterior to the optic chiasm 3,4.
Pallister-Hall syndrome is rare and the exact prevalence is unknown. Patients with posta...
Pallister-Killian syndrome (PKS) is an extremely rare chromosomal anomaly.
It may be more prevalent in births from women of advanced age 4.
Phenotypic expression can significantly vary from multiple anomalies resulting in perinatal death to the more charact...
Pancoast syndrome (historically known as Ciuffini-Pancoast-Tobías syndrome, Hare syndrome or variation thereof) results from involvement of the brachial plexus and sympathetic chain by a Pancoast tumor or, less commonly, from other tumors - or even non-malignant disease - involving the lung apex...
Pantothenate kinase-associated neurodegeneration (PKAN), historically also known as Hallervorden-Spatz syndrome, is an autosomal recessive disorder causing involuntary spasticity and progressive dementia. It is a subset of neurodegeneration with brain iron accumulation (NBIA).
Paradoxical brain herniation, also known as sinking skin flap syndrome or syndrome of the trephined, is a rare and potentially fatal complication of decompressive craniectomy.
Atmospheric pressure exceeding intracranial pressure at the craniectomy results in displacement of the brai...
Paraneoplastic syndromes occur secondary to the indirect effects of a malignancy and occur remotely to the primary malignancy. Symptoms are mediated by cytokines, hormones or immune cross-reactivity. These syndromes can cause a diverse range of symptoms and can affect multiple systems.
Parinaud syndrome, also known as the dorsal midbrain syndrome, is a supranuclear vertical gaze disturbance caused by compression of the superior tectal plate.
Parinaud syndrome is characterized by a classic triad of findings:
upward gaze palsy, often manifesting as diplo...
Parkinson-plus syndrome refers to a loose group of neurodegenerative disorders that are characterized by features of Parkinson disease but with other neurological symptoms/signs. They have a poor response to levodopa, and mostly have fairly characteristic neuroimaging features.
Parry-Romberg syndrome (PRS), also known as progressive facial hemiatrophy (PFH), is a rare progressive craniofacial disorder (phakomatosis).
It is classically characterized by a slow progressive degeneration (atrophy) of the soft tissues of half of the face (hemifacial atrophy). This involves ...
Parsonage-Turner syndrome is an acute idiopathic brachial neuritis.
There is male predominance (M:F 2:1 to 11.5:1) 1. Patients from 3 months to 85 years old have been reported, but the majority are between 3rd to 7th decade of life.
The presentation is typi...
Patau syndrome (also known as trisomy 13) is considered the 3rd commonest autosomal trisomy.
Patau syndrome along with Down syndrome (trisomy 21) and Edward syndrome (trisomy 18) are the only three trisomies to be compatible with extrauterine life. However, few infants live more than a few days...
Pelvic congestion syndrome (some prefer pelvic venous insufficiency 9) is a condition that results from retrograde flow through incompetent valves in ovarian veins. It is a commonly missed and potentially-treatable cause of chronic abdominopelvic pain.
It tends to be more common ...
Pendred syndrome is an autosomal recessively inherited disorder characterized by a euthyroid goiter associated with sensorineural hearing loss.
It is considered the most common form of syndromic hearing loss and accounts for upwards of 10% of hereditary deafness.
Pepper syndrome is of interest only (the term is not readily used in day-to-day practice), and refers to primary adrenal neuroblastoma with extensive liver metastases 1. In essence, it refers to stage 4S neuroblastoma (see staging of neuroblastoma).
Peroxisome biogenesis disorders (PBDs) are autosomal recessive, inborn errors of peroxisomes, a eukaryotic cell organelle critical to the breakdown of very long chain fatty acids via beta-oxidation.
There are two main groups 1:
Zellweger spectrum disorder (ZSD)
Perry syndrome is a rare, progressive, hereditary neurodegenerative movement disorder and TDP-43 proteinopathy.
Perry syndrome is considered to be very rare, generally isolated to select families who carry the mutation implicated in the disease 1,2. In one study, the age on onset ...
Peutz-Jeghers syndrome is one of the polyposis syndromes. It has an autosomal dominant inheritance and is characterized by:
multiple hamartomatous polyps, most commonly involving the small intestine (predominantly the ileum), but also colon and stomach; mouth and esophagus are spared
Pfeiffer syndrome (also known as type V acrocephalosyndactyly) is characterized by skull and limb abnormalities.
It affects about 1 in 100,000 births
PHACE syndrome, also known as cutaneous hemangioma–vascular complex syndrome or Pascual-Castroviejo type II syndrome, is a phakomatosis that comprises of:
P: posterior fossa malformations (e.g. Dandy-Walker malformation)
A: arterial anomalies
C: coarctation of the aorta and ca...
Phlegmasia cerulea dolens (PCD) is an uncommon complication of deep venous thrombosis, which results from extensive thrombotic occlusion of the major and collateral veins of an extremity (usually the legs).
Left leg is more commonly affected than the right 4.
Pickardt syndrome also known as Pickardt-Fahlbusch syndrome is a rare syndrome characterized by tertiary hypothyroidism, hyperprolactinemia and other pituitary hormone deficiencies resulting from interruption of the portal blood supply of the anterior pituitary via the infundibulum which drains ...
Pickwickian syndrome, or obesity hypoventilation syndrome (OHS), comprises the triad of obesity (BMI ≥30 kg/m2), daytime hypoventilation (awake hypercapnia and hypoxemia), and sleep-disordered breathing in the absence of alternative explanations (e.g. severe parenchymal lung disease, mechanical ...
Pinch-off syndrome is a spontaneous catheter fracture, which is seen as a complication of subclavian venous catheterization.
It is a known complication of central venous catheterization with a much-reduced incidence in current practice and is generally considered to be rare.
Pituitary stalk interruption syndrome, also known as pituitary stalk transection syndrome, is a syndrome characterized by an absent or hypoplastic anterior pituitary gland, thin or absent infundibulum, and ectopic posterior pituitary location.
Pituitary stalk interruption syndrome...
Plummer-Vinson syndrome, also known as the Paterson-Brown-Kelly syndrome, predisposes to hypopharyngeal squamous cell carcinoma and consists of four features:
esophageal webs or hypopharyngeal webs
The condition is more common in women.
POEMS syndrome is the acronymic name for a rare multisystem paraneoplastic disorder comprising of a minimum of three of the following features in the setting of a plasma cell dyscrasia:
hepatomegaly, splenomegaly or lymphadenopathy
Poland-Möbius syndrome, is the combination of Möbius syndrome and Poland syndrome, which although very rare, has been well described 1.
History and etymology
Sir Alfred Poland (1822-1872): English surgeon 2
Paul Julius Möbius (1853-1907): German neurologist 3
Poland syndrome refers to a congenital unilateral absence of the pectoralis major and minor muscles and is a recognized cause of unilateral hyperlucent hemithorax.
Poland syndrome is usually sporadic, although rare familial cases have been described 1. It is rare, with an estimat...
Polycystic ovarian syndrome (PCOS), recently referred also as hyperandrogenic anovulation, is a chronic anovulation syndrome associated with androgen excess.
The diagnosis of PCOS generally requires any two of the following three criteria for the diagnosis, as well as the exclusion of other et...
Polydactyly (less commonly called hyperdactyly) refers to the situation where there are more than the usual number of digits (five) in a hand or foot. It can be broadly classified as:
pre-axial polydactyly: extra digit(s) towards the thumb/hallux (radially)
post-axial polydactyly: extra digit(...
Polysplenia syndrome, also known as left isomerism, is a type of heterotaxy syndrome where there are multiple spleens congenitally as part of left-sided isomerism.
Polysplenia is seen predominantly in female patients. It is usually diagnosed in childhood or adulthood, later than a...
Popliteal artery entrapment syndrome (PAES) refers to symptomatic compression or occlusion of the popliteal artery due to a developmentally abnormal positioning of the popliteal artery in relation to its surrounding structures such as with the medial head of gastrocnemius (MHG) or less commonly ...
Post-ablation syndrome occurs from 24 to 48 hours following ablation and lasts no longer than 10 days 1. It is believed to occur following cytokine release and tumor necrosis, causing patient fever and flu-like symptoms.
If symptoms persist following 10 days after the procedure, alternate diagn...
Post-axial polydactyly refers to polydactyly where the additional digit is on the ulnar margin of the hand, or lateral to the 5th toe.
Post-axial polydactyly is more common than pre-axial polydactyly, with an estimated incidence of 1 in 3000 5.
The majority of cases ar...
Post-embolization syndrome (PES) is one of the most common side effects of transarterial embolization and chemoembolization. It comprises of a constellation of fever, nausea/vomiting, and pain. It is often a self-limiting phenomenon and usually occurs within the first 72 hours after embolization...
Posterior choroidal artery occlusion uncommonly presents as an isolated stroke syndrome. It usually coexists with posterior cerebral artery and often superior cerebellar artery involvement.
When seen in isolation damage is characteristically limited to the:
lateral geniculate body
Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic state that occurs secondary to the inability of the posterior circulation to autoregulate in response to acute changes in blood pressure. Hyperperfusion with resultant disruption of the blood brain barrier results in vasogenic e...
Posterior semicircular canal dehiscence syndrome (PSCD) is the presence of vestibuloauditory symptoms secondary to absence of the bony covering of the posterior semicircular canal (PSC).
It is thought to be rare: in a case series of 112 patients with a high riding jugular bulb it ...
Posterior spinal artery syndrome is a rare syndrome associated occlusion of the posterior spinal artery and results in a unilateral dorsal cord syndrome (since the posterior arteries are paired) 3.
The syndrome is clinically characterized by isolated loss of proprioception and vibratory sensat...
Post-pneumonectomy syndrome is delayed complication of pneumonectomy characterized by respiratory compromise caused by severe mediastinal shift and counterclockwise rotation of the heart and great vessels.
Rare delayed complication of pneumonectomy, which more commonly involves th...
Post-thrombotic syndrome (PTS) is a syndrome of chronic venous insufficiency following deep vein thrombosis (DVT) due to valvular incompetence, which results in chronic reflux and chronic venous hypertension.
PTS is a common complication following extensive DVT of the limbs. Up to...
PPP syndrome is the extremely rare association of pancreatitis, panniculitis, and polyarthritis.
Most commonly affects middle-aged male patients with a history of heavy alcohol use 1,2.
In the majority of cases, abdominal symptoms are mild or absent, makin...
Prader-Willi syndrome is a rare genetic disorder. It is the most common cause of obesity caused by a genetic syndrome.
Prader-Willi syndrome is primarily characterized by:
sexual infancy: hypogonadism
morbid obesity resulting from hyperphagi...
Pre-axial polydactyly refers to polydactyly where the additional digit is towards the first digit of the hand (radial side) or foot (medially).
Pre-axial polydactyly is less common than post-axial polydactyly, with an estimated incidence of 1 in 7000.
Primary progressive aphasia was first described in 1982 and is the umbrella term for the language-variant frontotemporal dementias associated with frontotemporal lobar degeneration (FTLD) 3.
It is an insidious disorder characterized by gradual impairment of speech and lan...
Progeria is a term used for any syndrome in which a person is prematurely aged, however, it most commonly refers to Hutchinson-Gilford progeria syndrome (HGPS).
Although the primary clinical manifestations of progeria include short stature and skin changes, the disease is...
Progressive postnatal pansynostosis (PPP) is a rare form of craniosynostosis characterized by the late fusion of all cranial sutures.
This type of craniosynostosis occurs insidiously after birth and presents later in life unlike other types of craniosynostosis which occur during t...
Pronator teres syndrome (also called pronator syndrome) is one of three common median nerve entrapment syndromes; the other two being anterior interosseous nerve syndrome and the far more common carpal tunnel syndrome. Signs and symptoms result from compression of the median nerve in the upper f...
Proteus syndrome is a rare congenital, multisystemic, hamartomatous condition characterized by asymmetrical overgrowth of almost any part of the body and a broad spectrum of manifestations. It can affect tissue from any germinal layer. It is suspected to be a genetic condition, but a particular ...
Pseudoxanthoma elasticum (PXE), also known as Grönblad–Strandberg syndrome, is a systemic condition characterized by the degeneration of elastic fibers. It has multiorgan manifestations.
Its prevalence is estimated to be around 1 in 25,000 9.
Patients may ...
PTEN (phosphatase and tensin homolog) gene mutation is associated with a few conditions known as PTEN-related diseases, with relatively similar clinical and radiological manifestations. They include:
Those not f...
Pulled elbow (also known as nursemaid's elbow) is a subluxation of the radial head into the annular ligament, which usually spontaneously or easily reduces and rarely demonstrates abnormal radiographic features. It should be distinguished from dislocation of the radial head.
Quadrangular space syndrome also known as quadrilateral space syndrome is an uncommon diagnosis mainly because of lack of literature on the subject and possible misdiagnosis.
Quadrangular space syndrome is present on ~1% of shoulder MRIs 6.
Radial tunnel syndrome is an entity that refers to entrapment of the radial nerve in the forearm, as it occurs in the supinator syndrome. Some authors believe this is an early form of the posterior interosseous nerve syndrome 5.
The syndrome is characterized by pain along...
Radiologically isolated syndrome (RIS) is defined by MRI findings suggestive of multiple sclerosis (MS) in asymptomatic ("clinically silent") patients. Radiological progression usually occurs in approximately 66% of patients with RIS, while ~33% per 5-year-period will subsequently develop neurol...
Raghib syndrome is a rare developmental complex. It consists of:
persistence of the left superior vena cava
coronary sinus ostial atresia
atrial septal defect
It has also been associated with other congenital malformations including ventricular septal defects, enlargement of the tricuspid an...
Raine syndrome, also known as lethal osteosclerotic bone dysplasia, is a very rare genetic disorder. Infants with this syndrome present with numerous characteristic craniofacial features as well as cerebral calcifications. Many individuals with this disorder are stillborn or die as neonates 4.
Ramsay Hunt syndrome (RMS), also known as herpes zoster oticus, is shingles of the facial nerve. It is due to reactivation of the varicella zoster virus in the geniculate ganglion.
Ramsay Hunt syndrome classically presents with a triad of 3,4:
facial nerve pal...
RAPADILINO syndrome is a rare autosomal-recessive syndrome that results from mutations in the RECQL4 gene 1.
RAPADILINO syndrome is a rare condition, prevalence is unknown. It is, however, more common and was first described in Finnish populations 2.
The acronym RAPADI...
Raymond syndrome is a posterior circulatory stroke syndrome due to a lesion in the ventral medial mid-pons. It is an extremely rare condition, with only a handful of cases described in the literature.
Clinically, 2 subtypes have been reported 1:
Raynaud phenomenon (also known as Raynaud syndrome) describes a localized vasculopathy whereby there is an exaggerated vascular response to cold temperature or emotional stresses.
Raynaud phenomenon is classified as being either 'primary' or idiopathic, or 'secondary' to another un...
Reactive arthritis (ReA) is a sterile inflammatory arthritis that follows an infection at a different site, commonly enteric or urogenital. It is classified as a type of seronegative spondyloarthropathy.
Reactive arthritis was formerly known as Reiter syndrome/disease, which is the...
Renal cysts and diabetes syndrome (RCAD), also known as maturity-onset diabetes of the young, type 5 (MODY5), refers to the combination of renal cortical cysts and diabetes mellitus in patients with mutations in the HNF1B gene. When renal cysts are associated with these mutations without disturb...
Rett syndrome is a rare neurodegenerative disease seen in young girls in the 2nd to 4th months of life. The majority of cases result from a mutation in the MECP2 gene; a more severe subset of the disease arises from a CDKL5 mutation1.
Following a period of normal developm...
Rhupus syndrome is a term traditionally used to describe patients uncommonly having the coexistence of
systemic lupus erythematosus (SLE) and
rheumatoid arthritis (RA)
The Rieger anomaly refers to the maldevelopment of the anterior chamber of the ocular globe. The iris and cornea do not form correctly, findings including:
hypoplastic iris stroma
corectopia: an off-center pupil in the iris
colobomas of the iris (pseudopolycoria)
Patients are at increased ri...
Right middle lobe syndrome refers to chronic right middle lobe collapse, without an obstructing lesion. It is usually with associated bronchiectasis.
Right middle lobe syndrome is usually encountered in older adults, with a predilection for women (see Lady Windermere syndrome). I...
Ritscher-Schinzel syndrome (RTSC), also known as 3C (cranio-cerebello-cardiac) syndrome, is a rare entity with a variable spectrum of CNS (primarily cerebellar), craniofacial, and congenital heart defects.
Roberts syndrome, also known as Roberts-SC phocomelia syndrome, pseudothalidomide syndrome, or Appelt-Gerken-Lenz syndrome, is a rare congenital malformation syndrome.
intrauterine growth restriction
postnatal growth retardation
failure to thrive
Robinow-Sorauf syndrome (RSS) is a rare, autosomal dominant type of acrocephalosyndactyly syndrome (ACS).
Rather than being a distinct ACS, it has now generally accepted that RSS is, in fact, part of the Saethre-Chotzen syndrome phenotypic spectrum 1. This is due to similar phenotype and both b...
Robinow syndrome is a rare heterogeneous genetic disorder with at least two distinct forms.
The syndrome can affect several systems, including:
mesomelic limb shortening: mesomelia
characteristic facies anomalies
Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy or Rosai-Dorfman-Destombes disease, is a rare benign idiopathic proliferative disease that involves phagocytic histiocytes.
The disease predominantly occurs in young adults with a mean age at pre...
Rotational vertebral artery occlusion syndrome, also known as bow hunter's syndrome, is a rare form of vertebrobasilar insufficiency secondary to dynamic compression of the usually-dominant vertebral artery.
It has many predisposing etiologies, but is most often due to large osteoph...
Rothmund-Thomson syndrome (RTS) is an extremely rare autosomal recessive disorder with heterogeneous clinical features.
It is characterized by many features which include:
poikiloderma: characteristic rash, typically develops in infancy
sparse hair, eyelashes, and/or ey...
Rubinstein-Taybi syndrome (RTS) is a very rare genetic multi-system disorder primarily characterized by intellectual disability, broad and often angulated thumbs and halluces, and distinctive facial features.
The estimated incidence is 1 in 100,000-125,000 live births 5.
Russell-Silver dwarfism is a very rare syndrome characterized by:
intrauterine growth restriction: tends to give an asymmetrical IUGR
postnatal growth restriction
relatively large calvarium: pseudohydrocephalus
clinodactyly/clinobrachydactyly of the small finger
a typical triangular type fa...
Ruvalcaba syndrome (also known as Ruvalcaba-Myhre-Smith syndrome) is one of a group of disorders related to the congenital skeletal disturbance. It is characterized by:
intellectual (not invariably) and physical disability
SADDAN syndrome is an acronym for severe achondroplasia with developmental delay and acanthosis nigricans. It is an extremely rare condition, and as the name states, comprises a combination of skeletal, brain and cutaneous anomalies.
The syndrome results from a mutation in ...
Saethre-Chotzen syndrome (also known as type III acrocephalosyndactyly) is characterized by limb and skull abnormalities.
It is the most common craniosynostosis syndrome and affects 1:25 - 50,000 individuals.
Males and females are equally affected.
The Sakati-Nyhan syndrome, also known as Sakati-Nyhan-Tisdale syndrome or acrocephalosyndactly type III, is an extremely rare type of acrocephalopolysyndactyly.
Its main features include:
congenital limb abnormalities
congenital heart defects
History and etymology
Sampson syndrome refers to a type of superficial endometriosis, where multiple superficial plaques may be seen scattered in the peritoneum and pelvic ligaments.
The patient may present with non-specific abdominal pain.
At laparoscopy, they are typi...
The SAPHO syndrome is an acronym that refers to a rare condition that is manifested by a combined occurrence of 2
It classically tends to present in young to middle-aged adults. Presentation in the pediatric popu...
Schimmelpenning syndrome is a rare and variable congenital multisystem condition characterized by extensive linear sebaceous nevi and multisystem neuroectodermal abnormalities. It is an epidermal nevus syndrome (ENS).
Classical triad including sebaceous nevi, seizures, an...
Schindler disease is a rare lysosomal storage disorder characterized by deficiency of alpha-N-acetylgalactosaminidase (alpha-NAGA or alpha-galactosidase B).
It is a rare disease with autosomal recessive inheritance.
Age and severity of presentation depends ...
Sclerosteosis is a rare autosomal recessive bone dysplasia resulting in sclerosis and hyperostosis, particularly of the skull, mandible and tubular bones. It is closely related to Van Buchem disease 1.
Sclerosteosis is a very rare disease, with only around 100 cases reported. Ther...