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 aetiologies, but is most often due to large osteophytes, atla...
Saccular cerebral aneurysms, also known as berry aneurysms, are intracranial aneurysms with a characteristic rounded shape and account for the vast majority of intracranial aneurysms. They are also the most common cause of non-traumatic subarachnoid haemorrhage.
When larger than 25...
The Sano shunt is a palliative surgical technique sometimes used as a step in Norwood procedure for hypoplastic left heart syndrome.
The procedure involves placement of an extracardiac conduit between the right ventricle and main pulmonary artery stump. This technique prevents the reduced diast...
The pectoral girdle has a rich plexus of arterial vessels that anastomose around the scapula and its muscles known as the scapular anastomosis. It functions to allow blood to flow around the scapula and shoulder joint if there is injury or occlusion. Contributing branches arise from as proximal...
Scimitar sign traditionally referred a catheter angiographic appearance, although it can also be seen on MRA and CTA. It denotes lateral displacement and stenosis of the popliteal artery in patients with cystic adventitial disease.
Scimitar syndrome, also known as hypogenetic lung syndrome, is characterised by a hypoplastic lung that is drained by an anomalous vein into the systemic venous system. It is a type of partial anomalous pulmonary venous return and is one of the several findings in congenital pulmonary venolobar ...
Secondary pulmonary arterial hypertension includes all cases of pulmonary arterial hypertension except for those for which no cause is identified with are then termed idiopathic pulmonary arterial hypertension.
The classification of pulmonary arterial hypertension into primary and secondary ha...
Segmental arterial mediolysis (SAM) is an increasingly recognised vascular disease of the middle-aged and elderly and a leading cause of spontanoeus intra-abdominal haemorrhage. It is characterised by fusiform aneurysms, stenoses, dissections and occlusions within splanchnic arterial branches. I...
The sentinel clot sign is a useful CT finding for the evaluation of probable anatomic sites of haemorrhage.
On CT, acute clotted haemorrhage typically has high attenuation (45 to 80 HU), whereas surrounding areas of acute nonclotted haemorrhage or more chronic haemorrhage have either lower atte...
Septal cerebral veins originate at the lateral aspect of the anterior horns of the lateral ventricles then pass medially, inferior to the genu of the corpus callosum. They then turn backwards and traverse along the septum pellucidum and enter the internal cerebral vein behind the foramen of Monr...
Shmoo sign refers to the appearance of a prominent, rounded left ventricle and dilated aorta on a plain AP chest radiograph giving the appearance of Shmoo, a fictional cartoon character in the comic strip Li'l Abner in the 1940s. This sign is indicative of left ventricular enlargement.
Shone syndrome is characterised by four congenital heart defects, largely multiple left sided obstructions:
supravalvular mitral membrane (SVMM)
subaortic stenosis (membranous or muscular)
parachute mitral valve
coarctation of the aorta
Shrinking lung syndrome (SLS) refers to a rare complication of systemic lupus erythematosus (SLE), and is characterised by:
restrictive pattern on pulmonary function tests
As with SLE in general, it is thought to carry a increased fem...
Sickle cell disease (SCD) is an autosomal recessive condition resulting in the formation of abnormal haemoglobin (a haemoglobinopathy), which manifests as multisystem ischaemia and infarction, as well as haemolytic anaemia.
There is no recognised gender predilection. The highest ...
Abdominal manifestations of sickle cell disease (SCD) are wide and can involve many organs.
For a general discussion, please refer to sickle cell disease.
splenic enlargement may occur transiently with the sequestration syndrome, where rapid pooling of blood occurs in th...
The sigmoid arteries are branches, between two-to-four, of the inferior mesenteric artery (IMA) and supply the sigmoid colon.
origin: inferior mesenteric artery
course: after arising from IMA, these branches descend to the left in the sigmoid mesocolon
superiorly with ...
The sigmoid sinus is a paired structure and one of the dural venous sinuses. It is the continuation of the transverse sinus (which is similarly variable in size) and becomes the sigmoid sinus as the tentorium ends. It is here that the sinus receives the superior petrosal sinus.
It passes inferi...
The signal flare phenomenon is a useful sign to identify active bleeding in a liquefied haematoma with haematocrit effect on dynamic CT scan images.
When active arterial haemorrhage is present in a liquefied haematoma that has a haematocrit effect, a signal flare phenomenon may be seen as a lin...
Erectile dysfunction is the occassional or consistent inability of a male to attain and maintain a penile erection sufficient enough and for a suffcient duration so as to allow vaginal penetration.
Erectile dysfunction is multifactorial in etiology. In general erectile dysfunction increases wit...
Single coronary arteries are rare (incidence 0.03-0.07%), with a higher incidence in patients with congenital heart disease (in particular truncus arteriosus and pulmonary atresia). They occur when there is a single ostia arising from the aorta with no ectopic ostia. There is a wide variety of c...
Single umbilical artery (SUA) results when there is a congenital absence of either the right or left umbilical artery. In the usual situation, there are paired umbilical arteries. For some unknown reason, the absence of the left umbilical artery is much more common (~70%).
The sinotubular junction is the region of the ascending aorta between the aortic sinuses (of Valsalva) and where the normal tubular configuration of the aorta is attained.
Sinus of Valsalva aneurysms are a cause of thoracic aortic dilatation. They can be either congenital or acquired (mycotic).
There is a male predilection (M:F ratio being around 3-4:1). They are relatively more common in eastern and Asian populations and can occur in any age group ...
Situs classification can be a daunting topic, but it falls into three main groups :
situs solitus: the normal configuration of thoracic and abdominal organs
situs inversus: mirror image of normal
situs ambiguus: an intermediate configuration with duplication (isomerism)
Situs is best thought...
Situs inversus, short form of the Latin “situs inversus viscerum”, is a term used to describe the inverted position of chest and abdominal organs. It is called situs inversus totalis when there is a total transposition of abdominal and thoracic viscera (mirror image of internal organs normal pos...
Situs solitus refers to the normal position of the thoracic and abdominal organs.
On plain radiograph, careful attention should be directed at the location of the aortic arch, gastric fundus, cardiac apex, pulmonary fissures and the branching pattern of ...
The small cardiac vein is a vein of the heart which accompanies the acute marginal artery from the RCA. It courses in the right posterior atrioventricular groove and drains into the coronary sinus close to it’s termination but may drain directly into the right atrium. It drains the right ventric...
The small saphenous vein (SSV) forms part of the superficial venous drainage of the lower limb.
Origin and course
The SSV forms by the confluence of the lateral aspect of the dorsal venous network of the foot (lateral marginal vein of the foot). It passes behind the lateral mall...
Soft-tissue sarcomas are a heterogeneous group of malignant tumours of mesenchymal origin (sarcoma) that originate from the soft tissues rather than bone. They are classified on the basis of tissue seen on histology. The commoner sarcomas in the adult and paediatric population are listed below.
Sonographic halo sign is used in a number of situations. They include:
hypoechoic halo sign in liver metastases: used in hepatobiliary imaging, is a concerning feature for malignant lesion if the lesion is a hyperechoic liver lesion 1,2
ultrasound halo in angiolymphoid hyperplasia with eosinop...
The Spetzler-Martin AVM grading system allocates points for various features of intracranial arteriovenous malformations to give a grade between 1 and 5. Grade 6 is used to describe inoperable lesions. The score correlates with operative outcome.
size of nidus
small (<3cm) = 1
The sphenopalatine artery, formerly known as the nasopalatine artery, is the terminal branch of the maxillary artery that is the main supply to the nasal cavity. It is colloquially know as the artery of epistaxis given its common involvement in cases of nose bleeds. It is a major contributor to ...
The sphenoparietal sinus is one of the dural venous sinuses and is located along the posteroinferior ridge of the lesser wing of the sphenoid bone. It drains into the cavernous sinus and receives tributaries from:
superficial middle cerebral vein
middle meningeal vein (frontal ramus)
Spinal arteriovenous malformations (AVMs) are characterised by arteriovenous shunting with a true nidus. They represent ~25% of spinal vascular malformations.
Different types of spinal AVM (see below) have differing age of presentation, but overall 80% present between the age 20 ...
Spinal arteriovenous malformations can be classified in a number of ways:
extramedullary: 80% 1
Or into four types 2:
type I: single coiled vessel (dural AV fistula)
type II: intramedullary glomus AVM
type III: juvenile
type IV: intradural perimedullary (AV fistula)
The spinal cord blood supply is formed by many different vessels with an extensive collateral supply and drainage.
The spinal cord is supplied by three longitudinal arteries:
single anterior spinal artery: supplies the anterior two-thirds of the spinal cord
paired posterior s...
Spinal vascular malformations (SVM) are rare but knowledge of them is important as if undiagnosed and untreated they can lead to serious complications.
There are two main types of SVMs 1,2:
spinal arteriovenous fistula (AVF): 70% of SVMs
pial: small, large, or giant
dural AVF (DA...
Splenial artery or posterior pericallosal artery arises most commonly from the parieto-occipital branch of the PCA. It represents an important collateral supply from the posterior to anterior cerebral arteries as it anastomoses with the pericallosal artery.
the splenial artery ...
The splenic artery is one of three branches coeliac trunk and supplies the spleen as well as large parts of the stomach and pancreas.
Origin and course
The splenic artery is one of the terminal branches of the coeliac trunk, passing from the coeliac axis toward the splenic hilum...
Splenic artery aneuryms are the commonest visceral arterial aneurysm formation as well as the 3rd commonest abdominal aneurysm (after the aorta and iliac vessels). Aneurysms are usually saccular in configuration and they can either be in the form of a true aneurysm (much more common) or as a pse...
Splenic artery pseudoaneurysms are a rare type of pseudoaneurysm arising from any portion of the splenic artery and its branches.
Unlike splenic artery true aneurysms, splenic artery pseudoaneurysms will nearly always present with symptoms 2. Fewer than 200 cases of sple...
Splenic steal syndrome is a possible complication after liver transplantation. In this syndrome, blood flows preferentially from the celiac artery into the splenic artery and the hepatic artery is relatively hypoperfused as a result. This complication can threaten a liver transplant's survival.
The splenic vein drains the spleen, part of the pancreas, and part of the stomach.
Origin and course
The splenic vein is formed by splenic tributaries emerging at the splenic hilum in the splenorenal ligament at the tip of the tail of pancreas. It runs in the splenorenal ligame...
Spontaneous retroperitoneal haemorrhage (SRH) is a distinctive clinical pathology of retroperitoneal bleeding without a preceding history of trauma.
Clinical presentation may be vague and varied:
no inciting history
no evidence of cutaneous bruising
back, lower abdomin...
The stag's antler sign refers to upper lobe pulmonary venous diversion (cephalisation) in pulmonary venous hypertension or pulmonary oedema as seen on frontal chest radiograph.
The prominence of upper lobe pulmonary veins resemble stag's antler. It is the earliest sign of pulmonary venous hyper...
Along with the DeBakey classification, the Stanford classification is used to separate aortic dissections into those that need surgical repair, and those that usually require only medical management. The Stanford classification divides dissections by the most proximal involvement:
type A: A aff...
Stewart-Treves syndrome refers to an angiosarcoma seen in the setting of post-mastectomy lymphoedema. It however only accounts for 10% of all angiosarcomas seen in the setting of chronic post-mastectomy lymphoedema.
The straight sinus is one of the main dural venous sinuses and is found at the junction between the falx cerebri and the tentorium cerebelli and is triangular in cross section.
It receives the inferior sagittal sinus, the vein of Galen at its anterior end and some superior cerebellar veins alo...
The string of beads sign is the description typically given to the appearance of the renal artery in fibromuscular dysplasia (FMD) but may also be used to describe the appearance of splanchnic arteries in segmental arterial mediolysis (SAM). It refers to the appearance arising from the stenoses ...
String of pearls sign can refer to:
string of pearls sign on an abdominal radiograph of fluid-filled dilated small-bowel loops
string of pearls sign on ultrasound in polycystic ovarian syndrome
string of pearls sign for angiographic appearances in fibromuscular dysplasia
The angiographic string sign, also known as the carotid string sign, refers to the thin string of intravenous contrast material distal to a stenotic focus in the internal carotid artery (ICA).
A thin stripe of flow is caused by decreased pressure and flow distal to the stenosis, whi...
The string sign may refer to:
angiographic string sign
gastrointestinal string sign
string sign of parosteal osteosarcoma
Stroke is a clinical designation that refers to the sudden neurological deficit resulting from a cerebrovascular event. It is divided into two broad categories:
ischaemic stroke (80% 2)
haemorrhagic stroke (15%)
secondary haemorrhages: some intrac...
The subclavian arteries are asymmetric paired arteries that supply blood to the posterior cerebral circulation, cerebellum, posterior neck, upper limbs and the superior and anterior chest wall.
Right and left subclavian arteries classically have different origins:
Helpful mnemonics to remember the branches of the subclavian artery include:
Very Indignant Tired Individuals Sip Strong Coffee Served Double Daily
VIT C, D (as in vitamins C and D).
Very Indignant Tired Individuals Sip Strong Coffee Served Double Daily
V: vertebral artery
Subclavian artery stenosis (SAS) refers to narrowing of one or both of the subclavian arteries.
The estimated in the general population as a whole is thought to be around 2-4%, while in those with peripheral vascular disease, it can be as high as 18% 1,4.
It can arise ...
Subclavian steal syndrome (SSS) and subclavian steal phenomenon both result from occlusion or severe stenosis of the proximal subclavian artery resulting in retrograde flow in the ipsilateral vertebral artery.
Subclavian steal phenomenon refers to steno-occlusive disease of the pro...
The subclavian vein (SCV) is the major venous channel that drains the upper limb.
Origin and course
The subclavian vein starts at the crossing of the lateral border of the 1st rib. It then arches cephalad, posterior to the medial clavicle before curving caudally and receiving it...
Subclavian vein stenosis refers to a narrowing of the subclavian vein.
Presentation can be variable ranging from being asymptomatic to having arm swelling, arm pain, paresthaesia, neck pain and occipital headaches.
Subclavian vein stenosis can arise from numbe...
The subcostal arteries are bilateral small arteries that arise of the distal descending aorta which courses laterally beneath the 12th rib. They are the last
The subcostal arteries are analogous to the posterior intercostal arteries, instead in the subcostal space rather than an...
The subscapular artery is the largest branch of the axillary artery.
The subscapular artery originates from the medial surface of the third part of the axillary artery. It passes along the inferior border of the subscapularis muscle and it divides into two branches 1,2:
The Sudeck point (or Sudeck critical point) refers to a specific location in the arterial supply of the rectosigmoid junction, namely the origin of the last sigmoid arterial branch from the inferior mesenteric artery (IMA) 1.
This arterial branch usually forms an anstomosis with a branch of th...
Sulcal arteries are penetrating branches of the anterior spinal artery which arise from the anterior spinal artery and extend posteriorly through the anterior median fissure of the cord. The sulcal arteries supply the anterior two-thirds of the spinal cord at any cross-sectional level.
Sulcal artery syndrome is a rare cause of spinal cord infarction involving the territory of one of the sulcal arteries, which are penetrating branches of the anterior spinal artery, each vessel supplying either left or right side of the cord, but not both. The result is an incomplete Brown-Séqua...
The superficial femoral artery is a continuation of the common femoral artery at the point where the profunda femoris branches. It is the main artery of the lower limb and is, therefore, critical in the supply of oxygenated blood to the leg.
origin: continuation of the common femoral a...
The superficial middle cerebral vein (SMCV) (also known as the Sylvian vein) is one of the superficial cerebral veins. It usually passes along the Sylvian fissure posteroanteriorly, it collects numerous small tubutaries which drain the opercular areas around the lateral sulcus. It curves anterio...
The superficial palmar branch of the radial artery (also known as the palmar cutaneous branch) is a small branch of the radial artery in the distal forearm. It arises from the radial artery just proximal to the flexor retinaculum, which it passes superficially over before entering the hand to su...
The superficial temporal artery is one of two terminal branches of the external carotid artery. It arises in the parotid gland and runs between the deep and superficial lobes, over the zygomatic process before terminating in three branches - parietal, frontal and transverse facial - to supply pa...
The superficial temporal vein arises in a plexus on the side and vertex of the skull and, in the substance of the parotid gland, joins with the maxillary vein to form the retromandibular vein.
The superficial temporal vein originates from a venous plexus on the side and vertex of...
Superficial thrombophlebitis, also called superficial venous thrombosis (SVT), is a pathological condition characterized by the presence of a thrombus in the lumen of a superficial vein, accompanied by inflammatory reaction of adjacent tissues.
Some authors however reserve the term...
Superficial veins of the brain predominantly drain the cerebral cortex, and include:
superior cerebral veins (or superficial cerebral veins)
inferior cerebral veins
superficial middle cerebral veins
superior anastomotic vein (of Trolard)
inferior anastomotic vein (of Labbe)
Some also inclu...
The superior adrenal (suprarenal) arteries area a group of one of the three adrenal arteries that supply the adrenal gland. There are usually numerous small arteries arising from the inferior phrenic artery.
The superior suprarenal arteries arise from the inferior phrenic...
The superior anastomotic vein (or vein of Trolard) connects the superior sagittal sinus and the superficial middle cerebral vein (of Sylvius).
Its size is dictated by the relative size of the superficial middle cerebral vein and the anastomotic vein of Labbé. The vein of Trolard is smaller than...
The superior cerebellar artery (SCA) arises from the distal basilar artery, just below the posterior cerebral artery (PCA) and typically supplies:
whole superior surface of the cerebellar hemispheres down to the great horizontal fissure
most of the cerebellar ...
Superior cerebellar artery infarcts affect the superior cerebellar hemispheres, cerebellar vermis and parts of the midbrain. The superior cerebellar artery is the most constantly identified vessel arising from the basilar artery with its origin just below the posterior cerebral artery in the dis...
The superior cerebral veins drain the superior portion of the cerebral cortex. They run up and medially before draining into the superior sagittal sinus. In a proportion of patients, a large such vein connects the superficial middle cerebral vein to the sinus, and is known as the superior anasto...
The superior epigastric artery is one of two terminal branches of the internal thoracic artery with the other being the musculophrenic artery.
Origin and course
The superior epigastric artery originates at the level of the sixth or seventh costal cartilage. It descends to the a...
The superior gluteal artery is the largest branch of the internal iliac artery and supplies structures within the pelvis and gluteal region.
origin: from the posterior division of the internal iliac artery
location: originates from pelvis and enters the gluteal region
The superior hypophyseal artery (or arteries) is a branch from the C6 segment of the internal carotid artery. It is usually a single trunk which then divides into many small branches, which go on to supply:
pituitary gland (anterior gland)
It is ofte...
The superior laryngeal artery accompanies the internal laryngeal branch of the superior laryngeal nerve, beneath the thyrohyoid muscle.
It pierces the thyrohyoid membrane, and supplies the muscles, mucous membrane, and glands of the larynx, anastomosing with the branch from the opposite side.
Superior mediastinum is an artificially divided wedge-shaped compartment of the mediastinum located between the thoracic plane inferiorly and the thoracic inlet superiorly. The inferior mediastinum, comprising of the anterior, middle and posterior parts, lies inferiorly.
Superior mesentertic arterial (SMA) dissection is an uncommon type of arterial dissection. It can either on its own (rarer) or occur as part of an extension of an aortic dissection.
A spontaneous dissection of the superior mesenteric artery (SMA) is considered the most frequently reported type...
The superior mesenteric artery (SMA) is one of the three non-paired arteries that provide blood to the midgut and other abdominal viscera.
Single vessel arising anteriorly from the abdominal aorta at the level of L1.
Courses anteroinferiorly, behind the neck of p...
There are two distinct vascular compression disorders due to compression of another structure by the superior mesenteric artery. The terminology is sometimes confusing and they can occur in association.
superior mesenteric artery syndrome (Wilkie syndrome): compression of the third part of th...
Superior mesenteric artery (SMA) syndrome, also known as Wilkie syndrome, is a rare acquired vascular compression disorder in which acute angulation of superior mesenteric artery (SMA) results in compression of the third part of the duodenum leading to obstruction.
It should not be confused wit...
The superior mesenteric vein (SMV) accompanies the superior mesenteric artery (SMA) and drains the midgut to the portal venous system.
Origin and course
Mesenteric venous arcades, which accompany the arteries, unite to form the jejunal and ileal veins in the small bowel mesenter...
The superior ophthalmic vein (SOV) is a prominent vein of the orbit that is seen on CT and may be enlarged or tortuous in various disease entities.
The vein forms at the confluence of several veins within the superior orbit above the medial palpebral ligament: the angular, suprat...
The superior pancreaticoduodenal artery is a branch of gastroduodenal artery that supplies the duodenum and pancreas.
Superior pancreaticoduodenal artery arises after branching off from gastroduodenal artery. It divides into anterior and posterior divisions which supply the pylor...
The superior petrosal sinus is one of the dural venous sinuses and drains the cavernous sinus, posterolaterally to the transverse sinus. It runs along superior aspect of the petrous temporal bone. It receives:
inferior cerebral veins
labyrinthine vein: draining the inner ear ...
The superior phrenic arteries are small branches arising either side from the lower part of the thoracic aorta just before it passes through the aortic hiatus. They anastamose with the pericardiophrenic and musculophrenic arteries to supply the superior surface of the diaphragm.
origin: the terminal branch of the inferior mesenteric artery is the superior rectal artery
course: descends into the pelvic cavity in the sigmoid mesocolon, crossing the left common iliac vessels
branches: opposite the S3 vertebra the superior rectal artery divides into two terminal ...
The superior sagittal sinus is the largest dural venous sinus. As the name suggests, it runs in a sagittal plane from the anterior aspect of the falx cerebri to its termination at the confluence of sinuses at the occipital protuberance, where it usually proceeds rightward and into the right tran...
The superior thoracic aperture, also known as the thoracic inlet or outlet, connects the root of the neck with the thorax.
The superior thoracic aperture is kidney-shaped and lies in an oblique transverse plane, tilted anteroinferiorly to posterosuperiorly.