Cranial Vascular Neurosurgery Flashcards
Which one of the following pathologies is most likely to give the appearances shown?
a. Atrial myxoma
b. Ehlers-Danlos syndrome
c. Fibromuscular dysplasia
d. Marfan syndrome
e. Polycystic kidney disease
c. Fibromuscular dysplasia
FMD occurs
predominantly in middle-aged women and
most often affects the cervical ICA (75%).
The vertebral (12%) and external carotid
arteries may also be involved. Disease is bilateral in 60% of cases. Angiographic images,
almost always with non-invasive techniques,
demonstrate alternating luminal narrowing
and dilatation, the resulting appearance often
described as a “string of beads.” This “corrugation” typically affects the mid ICA, usually
2 cm distal to bulb. Uni- or multifocal tubular stenoses are less common, and where observed, the degree of stenosis is usually
modest (less than 40%). FMD can occasionally be observed intracranially and is associated with aneurysms
Fibromuscular dysplasia. FMD occurs predominantly in middle-aged women and most often affects the cervical ICA (75%). The vertebral (12%) and external carotid arteries may also be involved. Disease is bilat- eral in 60% of cases. Angiographic images, almost always with non-invasive techniques, demonstrate alternating luminal narrowing and dilatation, the resulting appearance often described as a “string of beads.” This “corru- gation” typically affects the mid ICA, usually 2 cm distal to bulb. Uni- or multifocal tubu- lar stenoses are less common, and where observed, the degree of stenosis is usually modest (less than 40%). FMD can occasion- ally be observed intracranially and is associ- ated with aneurysms.
Which one of the following pathologies is most likely to give the appearances shown?
a. Anterior communicating artery aneurysm
b. Basilar tip aneurysm
c. Posterior communicating artery aneurysm
d.Posterior inferior cerebellar artery aneurysm
e. Middle cerebral artery aneurysm
a. Anterior communicating artery aneurysm
Anterior communicating artery aneu- rysm. The classical flame shaped hemorrhage associated with acute rupture of these aneu- rysms is depicted.
A33-year-oldmanpresentswithspontaneous tinnitus and nausea. Which one of the follow- ing is most likely based on the imaging shown?
a. Arteriovenous malformation
b. Cavernous angioma
c. Hemangioblastoma
d. Intracerebral hemorrhage
e. Medulloblastoma
b. Cavernous angioma
b—Cavernous angiomas are mulberry-like
lesions consisting of vascular spaces with little intervening tissue and hemorrhage of different ages. The incidence of clinically
symptomatic hemorrhage remains uncertain,
but is less frequent than with cerebral AVMs
or dural fistulae. A previous bleed and infratentorial location are the main prognostic
factors for recurrent hemorrhage. Lesions
in or close to the cerebral cortex may cause
epilepsy. They are occasionally intraventricular or arise on a cranial nerve. They appear
as relatively well-defined, dense, or calcified
lesions on CT, which may show patchy contrast enhancement. On MRI they appear
multilobular with mixed but predominantly
elevated T2 signal intensity centrally surrounded by a dark hemosiderin rim. Not surprisingly, susceptibility-based sequences are
the most sensitive. They may be multiple,
particularly in familial cases. In many clinical
situations the discovery of a cavernoma represents an incidental finding
Cavernous angiomas are mulberry-like lesions consisting of vascular spaces with lit- tle intervening tissue and hemorrhage of dif- ferent ages. The incidence of clinically symptomatic hemorrhage remains uncertain, but is less frequent than with cerebral AVMs or dural fistulae. A previous bleed and infra- tentorial location are the main prognostic factors for recurrent hemorrhage. Lesions in or close to the cerebral cortex may cause epilepsy. They are occasionally intraventric- ular or arise on a cranial nerve. They appear as relatively well-defined, dense, or calcified lesions on CT, which may show patchy con- trast enhancement. On MRI they appear multilobular with mixed but predominantly elevated T2 signal intensity centrally sur- rounded by a dark hemosiderin rim. Not sur- prisingly, susceptibility-based sequences are the most sensitive. They may be multiple, particularly in familial cases. In many clinical situations the discovery of a cavernoma rep- resents an incidental finding.
A 49-year-old man attends the Emergency department complaining of headache and vomiting for the last 2 days and now he has clumsiness of his left hand. There is no history of trauma. His GCS is 15/15. CT head shows there is a right sided acute subdural hematoma with midline shift of 5 mm. Which one of the following would you perform next?
a. CT intracranial angiogram
b. CT head with contrast
c. CT perfusion scan
d.MRI head with diffusion weighted sequences
e. Transcranial Doppler
a. CT intracranial angiogram
Occasionally, rupture of a cerebral aneurysm may
cause an acute subdural hematoma,most frequently
a posterior communicating artery aneurysm lying
next to the free edge of the tentorium cerebelli.
A dural arteriovenous fistula may also bleed into
the subdural space. Angiography is therefore
indicated following a spontaneous acute subdural
hematoma, particularly in a young patient prior
to craniotomy and evacuation of the clot
Occasionally, rupture of a cerebral aneurysm may cause an acute subdural hematoma, most frequently a posterior communicating artery aneurysm lying next to the free edge of the tentorium cerebelli. A dural arteriovenous fistula may also bleed into the subdural space. Angiography is therefore indicated following a spontaneous acute subdural hematoma, particularly in a young patient prior to craniotomy and evacuation of the clot.
Which one of the following is most likely given the image below?
a. Arachnoid cyst
b. Cavernous sinus meningioma
c. Craniopharyngioma
d. Giant MCA aneurysm
e. Pituitary macroadenoma
d. Giant MCA aneurysm
On MRI imaging, giant aneurysms have a characteristic appearance, as in this case. Findings
include signal void consistent with flow in the patent lumen; phase artifact related to flow, as is seen
in this case; and heterogeneous signal intensity
representing thrombi of varying ages.
On MRI imaging, giant aneurysms have a charac- teristic appearance, as in this case. Findings include signal void consistent with flow in the pat- ent lumen; phase artifact related to flow, as is seen in this case; and heterogeneous signal intensity representing thrombi of varying ages.
A 46-year-old female presents with sudden onset right facial numbness, hearing loss, and diplopia. CT head was unremarkable. Which one of the following therapies may be most appropriate based on the subsequent imaging shown?
a. Anticoagulant therapy
b. Balloon Angioplasty
c. Intra-arterial nimodipine
d. Surgical clipping
e. Thrombolytic therapy
a. Anticoagulant therapy
MRI shows a spontaneous right vertebral artery dissection—the
main treatment for which is anticoagulation
or antiplatelet therapy once subarachnoid
hemorrhage has been excluded. Intra-arterial thrombolytics have only been used in selected
cases.
The MRI shows a spon- taneous right vertebral artery dissection—the main treatment for which is anticoagulation or antiplatelet therapy once subarachnoid hemorrhage has been excluded. Intra-arterial thrombolytics have only been used in selected cases.
A 37-year-old man presents with seizures. Which one of the following is NOT thought to increase risk of hemorrhage in this type of lesion?
a. Deep venous drainage
b. Intranidal aneurysm
c. Prior hemorrhage
d. Single draining vein
e. Smoking
e. Smoking
Brain arteriovenous malformations (AVMs) are abnormal vascular anomalies within the brain, presumably congenital
in nature, but tend to present later in life
(20-40 years). There are several subgroups,
including the glomerular (most common)
and fistulous (less common) types of AVMs.
AVMs, often pial-based, are defined by
presence of arteriovenous shunting through
a nidus of coiled and tortuous vascular connections that connect feeding arteries to
draining veins, without a capillary bed. Most
(approximately 60-70%) of AVMs are
located in the cerebral hemispheres, 11-18%
within the cerebellum, and 13-16% in the
brainstem; 8-9% are deep-seated. Factors
that increase risk of hemorrhage from an
AVM include history of hypertension or previous hemorrhage, flow-related aneurysm,
intranidal aneurysm, deep venous drainage,
deep (periventricular) location, small nidus
size (<3 cm), high feeding artery pressure,
slow arterial filling, and venous stenosis.
Presence of intracranial hemorrhage indicates a poorer prognosis and is associated
with an increasing morbidity and mortality.
Presence of AVMs can lead to arterial steal
phenomenon, venous congestion, gliosis, or
hydrocephalus
Brainarteriovenousmalforma- tions (AVMs) are abnormal vascular anoma- lies within the brain, presumably congenital in nature, but tend to present later in life (20-40 years). There are several subgroups, including the glomerular (most common) and fistulous (less common) types of AVMs. AVMs, often pial-based, are defined by presence of arteriovenous shunting through a nidus of coiled and tortuous vascular con- nections that connect feeding arteries to draining veins, without a capillary bed. Most (approximately 60-70%) of AVMs are located in the cerebral hemispheres, 11-18% within the cerebellum, and 13-16% in the brainstem; 8-9% are deep-seated. Factors that increase risk of hemorrhage from an AVM include history of hypertension or pre- vious hemorrhage, flow-related aneurysm, intranidal aneurysm, deep venous drainage, deep (periventricular) location, small nidus size (<3 cm), high feeding artery pressure, slow arterial filling, and venous stenosis. Presence of intracranial hemorrhage indi- cates a poorer prognosis and is associated with an increasing morbidity and mortality. Presence of AVMs can lead to arterial steal phenomenon, venous congestion, gliosis, or hydrocephalus.
A 54-year-old woman presents with sudden onset severe headache. Her GCS is 15/15 with no neurological deficit on examination. Rup- ture of a vertebrobasilar aneurysm is thought to be responsible for the imaging appearances shown in what proportion of cases?
a. 2%
b. 4%
c. 6%
d. 8%
e. 10%
b. 4%
Nontraumatic, nonaneurysmal
perimesencephalic hemorrhage (PMH), presumably of venous origin, accounts for 96%
of all perimesencephalic hemorrhage. The
remaining 4% have been reported to result
from rupture of vertebrobasilar aneurysm.
Nontraumatic, nonaneurysmal perimesencephalic hemorrhage is characterized by relatively mild symptoms at onset, confinement
of the extravasated blood in the perimesencephalic cisterns, and absence of aneurysm. It
has a benign clinical course and excellent
prognosis.
Nontraumatic, nonaneurysmal
perimesencephalic hemorrhage (PMH), pre- sumably of venous origin, accounts for 96% of all perimesencephalic hemorrhage. The remaining 4% have been reported to result from rupture of vertebrobasilar aneurysm. Nontraumatic, nonaneurysmal perimesence- phalic hemorrhage is characterized by rela- tively mild symptoms at onset, confinement of the extravasated blood in the perimesence- phalic cisterns, and absence of aneurysm. It has a benign clinical course and excellent prognosis.
Which one of the following supraclinoid internal carotid artery aneurysm locations is most frequent?
a. Anterior choroidal artery aneurysm
b. Carotid bifurcation aneurysm
c. Hypophyseal artery aneurysm
d. Posterior communicating artery aneurysm
e. Supraopthalmic aneurysm
d. Posterior communicating artery aneurysm
Thirty-five percent of all intracranial aneurysms
arise at one of the following five sites along the
supraclinoid ICA
Thirty-five percent of all intracranial aneurysms arise at one of the following five sites along the supraclinoid ICA
Which one of the following pathologies is most likely demonstrated by the angiogram
a. Anterior choroidal artery aneurysm
b. Basilar tip aneurysm
c. MCA bifurcation
d. PCA aneurysm
e. Supraopthalmic aneurysm
e. Supraopthalmic aneurysm
These typically arise from the superior wall of the
carotid artery at the distal edge of the origin
of the ophthalmic artery close to the roof of
the cavernous sinus. At this point, the ICA
changes direction from superior toward posterior, so the maximal hemodynamic force is
directed toward the superior wall of the
carotid artery just distal to the ophthalmic
artery. Therefore, these aneurysms project
upward toward the optic nerve and are often
large with complex, multi-lobulated shape.
Surgical exposure may be difficult as the ophthalmic artery has a variable origin and
course and because multiple folds of the dura
enclose the region of the optic foramen and
clinoid process. Many are wide-necked aneurysms that may require remodeling techniques. Unruptured aneurysms may become
symptomatic due to headaches or compression of cranial nerves
These typi- cally arise from the superior wall of the carotid artery at the distal edge of the origin of the ophthalmic artery close to the roof of the cavernous sinus. At this point, the ICA changes direction from superior toward pos- terior, so the maximal hemodynamic force is directed toward the superior wall of the carotid artery just distal to the ophthalmic artery. Therefore, these aneurysms project upward toward the optic nerve and are often large with complex, multi-lobulated shape. Surgical exposure may be difficult as the oph- thalmic artery has a variable origin and course and because multiple folds of the dura enclose the region of the optic foramen and clinoid process. Many are wide-necked aneu- rysms that may require remodeling tech- niques. Unruptured aneurysms may become symptomatic due to headaches or compres- sion of cranial nerves.
Which one of the following is most likely based on this AP view of a right ICA injection?
a. A1 branch of ACA
b. Acomm artery
c. MCA bifurcation
d. M3 branch of MCA
e. Superior hypophysial artery
e. Superior hypophysial artery
aneurysms
arise just distal to the origin of the superior
hypophysial artery from the medial or posterior wall of the ICA where the curvature of the ICA is convex medially. In this location
they lie lateral to the pituitary stalk and point
medially under the optic chiasm. Medial
expansion of the aneurysm may compromise
the perforating arteries to the floor of the
third ventricle, the optic nerves, the chiasm,
the pituitary stalk, and the hypophysial vascular supply.
Superior hypophysial artery aneurysms arise just distal to the origin of the superior hypophysial artery from the medial or poste- rior wall of the ICA where the curvature of
the ICA is convex medially. In this location they lie lateral to the pituitary stalk and point medially under the optic chiasm. Medial expansion of the aneurysm may compromise the perforating arteries to the floor of the third ventricle, the optic nerves, the chiasm, the pituitary stalk, and the hypophysial vascu- lar supply.
Which one of the following clinical findings would you look for in this patient?
a. Abducens palsy
b. Absent corneal reflex
c. Bitemporal hemianopia
d. Oculomotor palsy
e. Pituitary dysfunction
d. Oculomotor palsy
The posterior communicating artery arises from
the posterior wall of the ICA where it forms a
posteriorly convex curve as it ascends to its terminal bifurcation under the anterior perforated substance. These aneurysms arise near the apex of
the posteriorly convex turn, immediately superior
to the distal edge of the origin of the posterior
communicating artery. They point downward
and posteriorly toward the oculomotor nerve,
so the posterior communicating artery is usually
found inferomedial to the neck of the aneurysm
(the anterior choroidal artery is found superior
or superolateral to the neck of the aneurysm).
The oculomotor nerve enters the dural roof of
the cavernous sinus lateral to the posterior clinoid
process and medial to a dural band that runs
between the tentorium cerebelli and the anterior
clinoid process. Posterior communicating artery
aneurysms larger than 4-5 mm may compress
the oculomotor nerve at its entrance into the
dural roof, causing opthalmoplegia
The posterior communicating artery arises from the posterior wall of the ICA where it forms a posteriorly convex curve as it ascends to its termi- nal bifurcation under the anterior perforated sub- stance. These aneurysms arise near the apex of the posteriorly convex turn, immediately superior to the distal edge of the origin of the posterior communicating artery. They point downward and posteriorly toward the oculomotor nerve, so the posterior communicating artery is usually found inferomedial to the neck of the aneurysm (the anterior choroidal artery is found superior or superolateral to the neck of the aneurysm). The oculomotor nerve enters the dural roof of the cavernous sinus lateral to the posterior clinoid process and medial to a dural band that runs between the tentorium cerebelli and the anterior clinoid process. Posterior communicating artery aneurysms larger than 4-5 mm may compress the oculomotor nerve at its entrance into the dural roof, causing opthalmoplegia.
Which one of the following pathologies is most likely demonstrated by the angiogram?
a. Anterior choroidal artery aneurysm
b. Anterior communicating artery aneurysm
c. Pericallosal aneurysm
d. Supraopthalmic aneurysm
e. Trigeminal artery aneurysm
a. Anterior choroidal artery aneurysm
Should the posteriorly convex curve of the supraclinoid ICA form its apex at the level of the anterior choroidal artery the hemodynamic force is
shifted distally from the origin of the posterior
communicating artery to the origin of the anterior choroidal artery. The anterior choroidal
aneurysms form just distal, superior, or superolateral to the origin of the anterior choroidal artery.
They also point posterior or posterolaterally but
are usually well above the oculomotor nerve.
Aneurysms arising from the choroidal segment
commonly have more perforating branches stretched around their neck than those arising from
the communicating or ophthalmic segment, because the choroidal segment has a greater number
of perforating branches arising from it and the
majority arise from the posterior wall, where the
neck of the aneurysm is situated
Should the posteriorly convex curve of the supra- clinoid ICA form its apex at the level of the ante- rior choroidal artery the hemodynamic force is shifted distally from the origin of the posterior communicating artery to the origin of the ante- rior choroidal artery. The anterior choroidal aneurysms form just distal, superior, or superolat- eral to the origin of the anterior choroidal artery. They also point posterior or posterolaterally but are usually well above the oculomotor nerve. Aneurysms arising from the choroidal segment commonly have more perforating branches stret- ched around their neck than those arising from the communicating or ophthalmic segment, beca- use the choroidal segment has a greater number of perforating branches arising from it and the majority arise from the posterior wall, where the neck of the aneurysm is situated.
The aneurysm type shown below constitutes which one of the following proportions of all intracranial aneurysms?
a. 1%
b. 5%
c. 15%
d. 25%
e. 35%
b. 5%
Aneurysms arise at the apex of the T-shaped
carotid bifurcation and point superiorly in the
direction of the long axis of the pre-bifurcation
segment of the artery. As they grow, they lie lateral
to the optic chiasm and may indent the undersurface of the anterior perforated substance. The
perforating branches arising from the choroidal
segment of the internal carotid and the proximal
segments of the anterior and middle cerebral
arteries are stretched around the posterior aspect
of the neck and wall of the aneurysm.
Aneurysms arise at the apex of the T-shaped carotid bifurcation and point superiorly in the direction of the long axis of the pre-bifurcation segment of the artery. As they grow, they lie lateral to the optic chiasm and may indent the undersur- face of the anterior perforated substance. The perforating branches arising from the choroidal segment of the internal carotid and the proximal segments of the anterior and middle cerebral arteries are stretched around the posterior aspect of the neck and wall of the aneurysm.
Which one of the following pathologies is most likely demonstrated by the angiogram?
a. Anterior communicating artery aneurysm
b. Basilar artery aneurysm
c. Basilar invagination
d. Left PCA artery aneurysm
e. Superior hypophyseal artery aneurysm
a. Anterior communicating artery aneurysm
Aneurysms of the ACA typically form close to the
anterior communicating artery complex. They
constitute about 30% of all intracranial aneurysms and are considered one of the most common types of aneurysm. They are frequently
associated with anatomical variants. Aneurysms
often occur when one A1 segment is hypoplastic
and the dominant A1 gives rise to both A2s. In
such case, the aneurysm arises at the level of
the anterior communicating artery at the point
where the dominant A1 segment bifurcates to
give rise to both the left and right A2 segments.
The direction in which the dome of the aneurysm
points is determined by the course of the dominant A1 segment proximal to its junction with
the anterior communicating artery. Thus, these
aneurysms usually point away from the dominant
segment toward the opposite side. Approaches to
anterior communicating artery aneurysms must
ensure that the anterior communicating artery
and the adjacent recurrent artery of Heubner
remain patent. The AcomA gives rise to small
perforating branches for the dorsal surface of
the optic chiasm and suprachiasmatic area that
perfuse the fornix, corpus callosum, and septal
region. Occlusion of the anterior communicating
artery may lead to personality disorders, even if
both A2 segments are perfused from their respective A1 segments. The recurrent artery of
Heubner arises, variably, from the distal A1, the
proximal A2, or the frontopolar branch of
the ACA before looping forward on the gyrus
rectus or the posterior part of the orbital surface
of the frontal lobe and then passing back over
the carotid bifurcation to accompany the MCA
and enter the anterior perforating substance
Aneurysms of the ACA typically form close to the anterior communicating artery complex. They constitute about 30% of all intracranial aneu- rysms and are considered one of the most com- mon types of aneurysm. They are frequently associated with anatomical variants. Aneurysms often occur when one A1 segment is hypoplastic and the dominant A1 gives rise to both A2s. In such case, the aneurysm arises at the level of the anterior communicating artery at the point where the dominant A1 segment bifurcates to give rise to both the left and right A2 segments. The direction in which the dome of the aneurysm points is determined by the course of the domi- nant A1 segment proximal to its junction with the anterior communicating artery. Thus, these aneurysms usually point away from the dominant segment toward the opposite side. Approaches to anterior communicating artery aneurysms must ensure that the anterior communicating artery and the adjacent recurrent artery of Heubner remain patent. The AcomA gives rise to small perforating branches for the dorsal surface of the optic chiasm and suprachiasmatic area that perfuse the fornix, corpus callosum, and septal region. Occlusion of the anterior communicating artery may lead to personality disorders, even if both A2 segments are perfused from their respec- tive A1 segments. The recurrent artery of Heubner arises, variably, from the distal A1, the proximal A2, or the frontopolar branch of the ACA before looping forward on the gyrus rectus or the posterior part of the orbital surface of the frontal lobe and then passing back over the carotid bifurcation to accompany the MCA and enter the anterior perforating substance.
Occlusion of the recurrent artery of Heubner may cause hemiparesis or aphasia.
The following appearances are seen during endovascular treatment of an anterior com- municating artery aneurysm. What is the next appropriate management step?
a. Ask the anesthetist to reduce systolic blood pressure to 100 mmHg
b. Check pupillary reflexes and perform CT head
c. Continue with endovascular treatment
d. ICP monitoring
e. Insertion of external ventricular drain
b. Check pupillary reflexes and perform CT head
This angiogram shows active extravasation of contrast material into the subarachnoid spaces, suggesting acute rupture of
this aneurysm necessitating clinical reassessment and surgical intervention if a
CheckpupillaryreflexesandperformCT head. This angiogram shows active extravasa- tion of contrast material into the subarach- noid spaces, suggesting acute rupture of this aneurysm necessitating clinical reassess- ment and surgical intervention if appropriate.
Which one of the following pathologies is most likely demonstrated by the angiogram?
a. A1 branch of ACA aneurysm
b. Corpocallosal AVM
c. MCA bifurcation aneurysm
d. Pericallosal aneurysm
e. Posterior communicating artery aneurysm
d. Pericallosal aneurysm
The second most common aneurysm of the ACA
is the so-called pericallosal aneurysm, which
arises at the origin of the callosomarginal artery
from the pericallosal artery, usually in close proximity to the anterior portion of the corpus callosum, near the point where the genu of the ACA
has its greatest angulation. Pericallosal aneurysms
account for approximately 3% of all intracranial
aneurysms. They point distally into the window
between the junction of the pericallosal and callosomarginal arteries
The second most common aneurysm of the ACA
is the so-called pericallosal aneurysm, which arises at the origin of the callosomarginal artery from the pericallosal artery, usually in close prox- imity to the anterior portion of the corpus callo- sum, near the point where the genu of the ACA has its greatest angulation. Pericallosal aneurysms account for approximately 3% of all intracranial aneurysms. They point distally into the window between the junction of the pericallosal and callo- somarginal arteries.
Which one of the following is most likely
demonstrated by the angiogram?
a. Anterior communicating artery
b. MCA bifurcation aneurysm
c. Pericallosal aneurysm
d. Posterior communicating artery
e. Terminal ICA aneurysm
b. MCA bifurcation aneurysm
Approximately 15% of all saccular aneurysms
arise from the MCA. Typically they originate at
the level of the first major bifurcation or trifurcation of the artery and point laterally in the
direction of the long axis of the pre-bifurcation
segment of the MCA. The more proximal the
bifurcation, the greater the number of lenticulostriate branches arising distal to the bifurcation
that may be stretched around the neck of the
MCA aneurysm. When unruptured, these aneurysms are typically clinically silent. Proximal
M1 segment aneurysms at origins of lenticulostriate arteries are exceedingly rare but when present
tend to point upward toward the anterior perforated substance. MCA aneurysms may also arise
from the temporopolar branch of the M1 segment. When present, these tend to point inferiorly. Aneurysms distal to the MCA bifurcation
are rare and are typically encountered in the setting of infectious diseases
Approximately 15% of all saccular aneurysms arise from the MCA. Typically they originate at the level of the first major bifurcation or trifur- cation of the artery and point laterally in the direction of the long axis of the pre-bifurcation segment of the MCA. The more proximal the bifurcation, the greater the number of lenticu- lostriate branches arising distal to the bifurcation that may be stretched around the neck of the MCA aneurysm. When unruptured, these aneu- rysms are typically clinically silent. Proximal M1 segment aneurysms at origins of lenticulostri- ate arteries are exceedingly rare but when present tend to point upward toward the anterior perfo- rated substance. MCA aneurysms may also arise from the temporopolar branch of the M1 seg- ment. When present, these tend to point inferi- orly. Aneurysms distal to the MCA bifurcation are rare and are typically encountered in the set- ting of infectious diseases.
Which one of the following pathologies is most likely demonstrated by the angiogram?
a. Anterior inferior cerebellar artery aneurysm
b. Basilar tip aneurysm
c. Posterior cerebral artery aneurysm
d. Posterior inferior cerebellar artery aneurysm
e. Superior cerebellar artery aneurysm
d. Posterior inferior cerebellar artery aneurysm
Most aneurysms of the vertebral artery take origin
at the posterior inferior cerebellar artery (PICA),
especially when the origin of the PICA falls at the
apex of a superiorly directed curve of the vertebral
artery. These aneurysms almost invariably point
upward and usually communicate widely with
the PICA. The size of the territory supplied by
the PICA varies widely, and will influence the best
approach to aneurysm therapy. Common anatomic variants associated with the vertebral artery
include unilateral agenesis/hypoplasia, double
(duplicated, fenestrated) origin, and extracranial
or epidural origin. There are close reciprocal
inverse relationships among the sizes of the hemispheric territories supplied by the PICA, AICA,
and SCA. Any one may annex (part of) the territory of the adjacent vessel, commonly leading to
variations such as the AICA-PICA trunk. PICA
supply to both cerebellar hemispheres is very
uncommon but does occur and must be considered prior to endovascular procedures
Most aneurysms of the vertebral artery take origin at the posterior inferior cerebellar artery (PICA), especially when the origin of the PICA falls at the apex of a superiorly directed curve of the vertebral artery. These aneurysms almost invariably point upward and usually communicate widely with the PICA. The size of the territory supplied by the PICA varies widely, and will influence the best approach to aneurysm therapy. Common ana- tomic variants associated with the vertebral artery include unilateral agenesis/hypoplasia, double (duplicated, fenestrated) origin, and extracranial or epidural origin. There are close reciprocal inverse relationships among the sizes of the hemi- spheric territories supplied by the PICA, AICA, and SCA. Any one may annex (part of) the terri- tory of the adjacent vessel, commonly leading to variations such as the AICA-PICA trunk. PICA supply to both cerebellar hemispheres is very uncommon but does occur and must be consid- ered prior to endovascular procedures.
Which one of the following pathologies is most likely demonstrated by the angiogram?
a. Asymmetric fusion of caudal divisions of fetal ICA
b. Basilar fenestration
c. Basilar invagination
d. Fetal origin of PCA
e. Hypoplastic posterior communicating
artery
b. Basilar fenestration
The incidence of basilar artery aneurysms
increases when the basilar system shows anomalous or variant architecture, including basilar
nonfusion (fenestration), asymmetric or caudal
fusion of the caudal divisions of the fetal ICA,
hypoplastic communicating artery, or fetal (persistent carotid) origin of the posterior cerebral
artery. Proximal non-dissecting basilar artery
aneurysms are rare and typically arise in patients
with failure to form a single basilar artery during
embryologic development. The single basilar
artery normally develops by union of paired longitudinal neural arteries that fuse together by
about the fifth fetal week (when the embryo is
9 mm long). Each of the longitudinal neural
arteries gives rise to the perforating arteries for
its own side of the brain stem. Failed fusion of
the neural arteries is often associated with aneurysms at the proximal portion of the nonfused
artery. The lateral walls of the unfused arteries
have normal intrinsic architecture. At the base
of the medial wall, however, the media is absent,
the elastic is discontinuous, and the subendothelium is thinned. These segments are more likely
to develop arterial aneurysms when subject to
secondary “offensive” triggers such as hemodynamic stress. The surgical treatment of these
aneurysms is difficult due to their relationship to the cranium, lower cranial nerves, and the
complex surgical approaches to this region.
Endovascular embolization of aneurysms at an
unfused basilar artery is an alternative to surgery.
However, it must be recognized that both limbs
of the unfused basilar artery have to be preserved,
that the neck of such aneurysms is often broad,
and that the aneurysm may regrow due to the
unfavorable hemodynamics at the site of an
unfused segment.
The incidence of basilar artery aneurysms increases when the basilar system shows anoma- lous or variant architecture, including basilar nonfusion (fenestration), asymmetric or caudal fusion of the caudal divisions of the fetal ICA, hypoplastic communicating artery, or fetal (per- sistent carotid) origin of the posterior cerebral artery. Proximal non-dissecting basilar artery aneurysms are rare and typically arise in patients with failure to form a single basilar artery during embryologic development. The single basilar artery normally develops by union of paired lon- gitudinal neural arteries that fuse together by about the fifth fetal week (when the embryo is 9 mm long). Each of the longitudinal neural arteries gives rise to the perforating arteries for its own side of the brain stem. Failed fusion of the neural arteries is often associated with aneu- rysms at the proximal portion of the nonfused artery. The lateral walls of the unfused arteries have normal intrinsic architecture. At the base of the medial wall, however, the media is absent, the elastic is discontinuous, and the subendothe- lium is thinned. These segments are more likely to develop arterial aneurysms when subject to secondary “offensive” triggers such as hemody- namic stress. The surgical treatment of these aneurysms is difficult due to their relationship to the cranium, lower cranial nerves, and the complex surgical approaches to this region. Endovascular embolization of aneurysms at an unfused basilar artery is an alternative to surgery. However, it must be recognized that both limbs of the unfused basilar artery have to be preserved, that the neck of such aneurysms is often broad, and that the aneurysm may regrow due to the unfavorable hemodynamics at the site of an unfused segment.
Which one of the following clinical findings would you look for in this patient?
a. Abducens palsy
b. Internuclear opthalmoplegia
c. Occulomotor palsy
d. Parinaud’s syndrome
e. Trochlear palsy
c. Occulomotor palsy
Basilar artery aneurysms at the level of the SCA
often arise where the upper basilar artery curves
and tilts, so the hemodynamic thrust created by
flow along the basilar artery impacts just above
the origin of the SCA rather than at the basilar
apex. SCA aneurysms often have a broad connection with the SCA, a rather large neck, and a
neck-to-dome ratio that makes endovascular
therapy demanding. Endovascular therapy must
attempt to preserve this artery, because this is
the major vessel to supply the deep nuclei of
the cerebellum. Large SCA aneurysms may cause
oculomotor nerve palsies by direct impression on
the oculomotor nerve as it courses through the
interpeduncular cistern just cranial to the SCA
Basilar artery aneurysms at the level of the SCA often arise where the upper basilar artery curves and tilts, so the hemodynamic thrust created by flow along the basilar artery impacts just above the origin of the SCA rather than at the basilar apex. SCA aneurysms often have a broad connec- tion with the SCA, a rather large neck, and a neck-to-dome ratio that makes endovascular therapy demanding. Endovascular therapy must attempt to preserve this artery, because this is the major vessel to supply the deep nuclei of the cerebellum. Large SCA aneurysms may cause oculomotor nerve palsies by direct impression on the oculomotor nerve as it courses through the interpeduncular cistern just cranial to the SCA
Which one of the following pathologies is most likely demonstrated by the angiogram?
a. Basilar fenestration
b. Basilar tip aneurysm
c. Persistent trigeminal artery
d. Persistent otic artery
e. Vertebral artery occlusion
b. Basilar tip aneurysm
About 15% of saccular aneurysms occur in the
vertebrobasilar system and of these 60% arise at
the basilar bifurcation where the posterior cerebral arteries branch off from the tip of the basilar
artery. At the aneurysm site the blood flow
changes from vertical to nearly horizontal, so
these aneurysms project upward in the direction
of the long axis of the basilar artery. The largest
and most important perforators to arise from the
basilar tip are the posterior thalamoperforate
arteries (retromammillary arteries). These originate from the basilar tip and P1, enter the brain
through the posterior perforated substance in
the interpeduncular fossa medial to the cerebral
peduncles, and ascend through the midbrain to
the thalamus. The risks from occlusion of these
vital perforating vessels include visual loss, paralysis, sensory disturbances, weakness, memory deficits, autonomic and endocrine imbalance,
abnormal movements, diplopia, and depression of
consciousness. Endovascular approaches have been widely adopted to treat basilar apex aneurysms,
because the surgical approach is associated with a
higher morbidity. This is especially true for the
more posterior basilar tip aneurysms, because
greater numbers of vital thalamoperforators are
affected as the aneurysm enlarges and projects
more deeply into the interpeduncular fossa
About 15% of saccular aneurysms occur in the vertebrobasilar system and of these 60% arise at the basilar bifurcation where the posterior cere- bral arteries branch off from the tip of the basilar artery. At the aneurysm site the blood flow changes from vertical to nearly horizontal, so these aneurysms project upward in the direction of the long axis of the basilar artery. The largest and most important perforators to arise from the basilar tip are the posterior thalamoperforate arteries (retromammillary arteries). These origi- nate from the basilar tip and P1, enter the brain through the posterior perforated substance in the interpeduncular fossa medial to the cerebral peduncles, and ascend through the midbrain to the thalamus. The risks from occlusion of these vital perforating vessels include visual loss, paral- ysis, sensory disturbances, weakness, memory def- icits, autonomic and endocrine imbalance, abnormal movements, diplopia, and depression of consciousness. Endovascular approaches have been About 15% of saccular aneurysms occur in the vertebrobasilar system and of these 60% arise at the basilar bifurcation where the posterior cere- bral arteries branch off from the tip of the basilar artery. At the aneurysm site the blood flow changes from vertical to nearly horizontal, so these aneurysms project upward in the direction of the long axis of the basilar artery. The largest and most important perforators to arise from the basilar tip are the posterior thalamoperforate arteries (retromammillary arteries). These origi- nate from the basilar tip and P1, enter the brain through the posterior perforated substance in the interpeduncular fossa medial to the cerebral peduncles, and ascend through the midbrain to the thalamus. The risks from occlusion of these vital perforating vessels include visual loss, paral- ysis, sensory disturbances, weakness, memory def- icits, autonomic and endocrine imbalance, abnormal movements, diplopia, and depression of consciousness. Endovascular approaches have been
Which one of the following mechanisms is most likely responsible for the finding in the angiogram?
a. Connective tissue disorder
b. Infection
c. Traumatic dissection
d. Neoplasia
e. Toxin
c. Traumatic dissection
ntradural traumatic aneurysms most commonly involve the internal carotid and vertebral arteries at their transdural portions. Traumatic aneu- rysms may result from penetrating injuries such as a stabbing accident, a high-velocity gunshot wound, or iatrogenic trauma (e.g., third ventricu- lostomy). Similarly, traumatic arterial aneurysms have been described as involving the ACA along the falx and the tentorium, either following major head injuries or as part of the shaken baby syn- drome. Distal posterior cerebral artery aneurysm are most likely dissecting in nature. They typi- cally appear at the junction between the P2 and P3 segments, where the PCA crosses the tentor- ium resulting in microtrauma. Angiographic cri- teria for spontaneous dissections are the stagnation of the contrast medium in an aneurysmal pouch, the presence of stenotic segments proximal and/or distal to the ectasia, and a fusiform appearance of the aneurysm. Spontaneous hemorrhagic
EMI ANSWERS
intracranial dissection is an uncommon disease but has been increasingly recognized as a cause for SAH with an unfavorable prognosis and a high rebleeding rate. One percent to 10% of all intracra- nial nontraumatic SAH is thought to result from ruptured intracranial dissections. This rate may rise to 5-20% in young patients. The choice of treatment and its timing continue to be controversial. Acutely ruptured dissections are unstable. Up to 70% of cases rebleed, often soon after the initial hemor- rhage, with a mortality rate from rebleeding as high as 50%. After SAH, 70% of rebleeding occurs within the first 24 h, with 80% occurring within the first week. The rebleeding rate decreases consider- ably beyond the first week after initial hemorrhage, and only 10% of rebleeding occurs more than 1 month after the initial hemorrhage. The dissection may lead to an extensive mural hematoma that may compress perforating arteries close to the site of dissection. Treatment should be targeted at exclud- ing the damaged vessel wall segment from the circulation, either endovascularly or via surgical approaches.
