(1)
Neurosurgery Teaching Hospital, Baghdad, Iraq
This book contains some difficult questions marked with “ * “ sign.
- 1.
Intracranial aneurysms
General, the FALSE answer is:
- A.
Intracranial aneurysms affect 5–10 % of the general population.
- B.
The Acom region is the most common site for intracranial aneurysms.
- C.
ICA is the second most common location.
- D.
MCA is more common than ICA location.
- E.
Ratio of ruptured: unruptured intracranial aneurysms is about 50 %.
- A.
The answer is D.
ICA is the second most common location, while MCA is the third most common location.
Intracranial aneurysms affect 5–10 % of the general population.
The Acom region is the most common site for intracranial aneurysms. However, aneurysms in this location can be missed on angiography.
Ratio of ruptured: unruptured (incidental) aneurysm is 5:3–5:6 (rough estimate is 1:1).
- 2.
Intracranial aneurysms
General (anterior circulation), the FALSE answer is:
- A.
Incidence of Acom-ACA aneurysms is 39 %.
- B.
Incidence of Pcom aneurysms is 25 %.
- C.
Incidence of MCA aneurysms is 20 %.
- D.
Incidence of DACA is 6 %.
- E.
MCA aneurysms usually at the M3/M4 junction.
- A.
The answer is E.
Incidence of MCA aneurysms (usually at the M1/M2 junction) is 20 %.
- 3.
Intracranial aneurysms
General (posterior circulation), the FALSE answer is:
- A.
Approximately 15 % of saccular aneurysms occur in the vertebro-basilar system.
- B.
Dissections and fusiform aneurysms are more common in the posterior than in the anterior circulation.
- C.
Posterior circulation aneurysms occur most often at the basilar tip followed by the origins of SCA and PICA.
- D.
Basilar tip aneurysms account for 50 % of posterior circulation aneurysms.
- E.
Vertebral artery aneurysms account for 5 % of posterior circulation aneurysms.
- A.
The answer is E.
VA aneurysms account for 5 % of all intracranial aneurysms.
VA-PICA junction is the most common site in vertebral artery aneurysms.
- 4.
Intracranial aneurysms
General, the FALSE answer is:
- A.
Incidence of pediatric intracranial aneurysms is 20 %.
- B.
Incidence of multiple aneurysms is 15–20 %.
- C.
Incidence of giant aneurysms is 2–5 %.
- D.
Incidence of infectious intracranial aneurysms is 2–5 %.
- E.
Incidence of traumatic intracranial aneurysms is 1 %.
- A.
The answer is A.
Only 2 % of aneurysms present during childhood.
- 5.
Intracranial aneurysms
General, the FALSE answer is:
- A.
Acom complex is the commonest location for ruptured aneurysms.
- B.
Acom complex is also the commonest for coincidental and unruptured aneurysms.
- C.
Unusual aneurysm locations should alert one to possible unusual causes like infection.
- D.
Medially directed carotid cavernous aneurysm may be the result of arterial damage during paranasal sinus surgery or hypophysectomy.
- E.
Distal vertebral fusiform aneurysms are likely to be due to dissection.
- A.
The answer is B.
MCA is the commonest for coincidental and unruptured aneurysms.
- 6.
Intracranial aneurysms
General rules of aneurysm formation, the FALSE answer is:
- A.
Aneurysms arise at a branching site on the parent artery.
- B.
Fusiform aneurysms arise at a turn or curve in the artery.
- C.
The aneurysm dome or fundus points in the direction of the maximal hemodynamic thrust.
- D.
There is a constantly occurring set of perforating arteries situated at each aneurysm site that need to be protected and preserved.
- E.
Most of the persistent carotid-basilar anastomoses have been reported to be associated with aneurysms and SAH.
- A.
The answer is B.
Saccular aneurysms arise at a turn or curve in the artery.
In 1979, Rhoton introduced three rules related to the anatomy of saccular aneurysms that should be considered when planning the operative approach to these lesions.
First, these aneurysms arise at a branching site on the parent artery. This site may be formed either by the origin of a side branch from the parent artery, such as the origin of the Pcom from the ICA, or by subdivision of a main arterial trunk into two trunks, as occurs at the bifurcation of the middle cerebral or basilar arteries.
Second, saccular aneurysms arise at a turn or curve in the artery. These curves, by producing local alterations in intravascular hemodynamics, exert unusual stresses on apical regions that receive the greatest force of the pulse wave. Saccular aneurysms arise on the convex, not concave, side of the curve.
Third, saccular aneurysms point in the direction that the blood would have gone if the curve at the aneurysm site were not present. The aneurysm dome or fundus points in the direction of the maximal hemodynamic thrust in the pre-aneurysmal segment of the parent artery.
Since the original introduction of the three rules, new anatomic studies have revealed a fourth rule. The fourth rule is that there is a constantly occurring set of perforating arteries situated at each aneurysm site that need to be protected and preserved to achieve an optimal result.
A fifth rule was added which state that all of the persistent carotid-basilar anastomoses have been reported in association with aneurysms and SAH, including the trigeminal, hypoglossal, otic, and proatlantal arteries.
- 7.
Intracranial aneurysms*
General relevant anatomy (anomalies of ACA), the FALSE answer is:
- A.
Type I anomaly: azygous (single) ACA is rare.
- B.
Type III anomaly is the most common type.
- C.
Type III anomaly includes unpaired ACA.
- D.
The A1 segments are equal in size in only 19 %.
- E.
Not infrequently, a hypoplastic A1 segment is associated with a large Acom.
- A.
The answer is C.
Anomalies of ACA are common, especially in patients with aneurysms.
Azygous ACA, the “unpaired ACA” (type I anomaly) is rare.
Type II anomaly is “bihemispheric ACA” as an A2 segment of the ACA that sends branches across the midline to both hemispheres, usually in the presence of a contralateral A2 segment that is either hypoplastic or that terminates early in its course toward the genu of the corpus callosum.
The most common (type III anomaly) is the “accessory ACA,” defined as a third artery originating from the Acom, in addition to the paired A2, usually in the midline and with branches to one or both hemispheres.
Not infrequently, a hypoplastic A1 segment is associated with a large Acom, and aneurysms arise from the side of the large ACA in over 95 %.
- 8.
Intracranial aneurysms
General relevant anatomy, the FALSE answer is:
- A.
The recurrent artery of Heubner runs parallel to the A2.
- B.
The recurrent artery of Heubner usually arises from A2 segment in about 90 % of patients.
- C.
Pcom is hypoplastic in about 10 % of the patients.
- D.
AChA is duplicated in about 30 % of patients.
- E.
MCA has a trifurcation instead of bifurcation in about 20 % of the patients.
- A.
The answer is A.
The recurrent artery of Heubner runs parallel to the A1 then parallel to the M1.
The recurrent artery of Heubner usually arises from A2 segment just distal to Acom in 86–92 % of cases.
- 9.
Intracranial aneurysms
General relevant anatomy, the FALSE answer is:
- A.
The PCA has a fetal origin (arising from the ICA) in 15–22 % of individuals.
- B.
The labyrinthine artery arises from AICA in about 85 % of the patients.
- C.
Vertebral artery may be hypoplastic and lacking functional significance in 3 % of individuals.
- D.
PICA is quite variable and may be absent in about 10 % of individuals.
- E.
Artery of Percheron is the name of posterior thalamoperforators when it is bilateral and asymmetric territory.
- A.
The answer is E.
The posterior thalamoperforators arise from the P1 segments, with the majority arising from the middle third as individual branches or branching trunks that can be bilateral and symmetric, bilateral and asymmetric, or unilateral with bilateral territory (artery of Percheron).
- 10.
Intracranial aneurysms
General cisternal anatomy, the FALSE answer is:
- A.
Carotid cistern is containing the ICA and the origin of its branches.
- B.
Sylvian cistern is containing the MCA and extends back into the sylvian fissure.
- C.
Olfactory cistern is containing the olfactory tract.
- D.
Chiasmatic cistern is containing the oculomotor nerve and the pituitary gland.
- E.
Lamina terminalis cistern is containing ACA, Acom, and their branches (in the midline).
- A.
The answer is D.
Chiasmatic cistern is containing the optic nerves, chiasm, and the pituitary stalk (in the midline).
Also the interpeduncular cistern is containing Pcom and their branches, the oculomotor nerves, and many components of the basilar artery circulation.
- 11.
Intracranial aneurysms
Genetics (autosomal dominant polycystic kidney disease (ADPKD)), the FALSE answer is:
- A.
ADPKD accounts for 2–7 % of all intracranial aneurysms.
- B.
Intracranial aneurysms are detected in approximately 25 % of patients with ADPKD at autopsy; those are more likely to be male.
- C.
Aneurysmal SAH in patients with ADPKD occurs at an earlier age, but the mortality rate is similar.
- D.
Renal ultrasonography is a noninvasive and reliable technique and should therefore be considered to rule out ADPKD.
- E.
Intracranial aneurysm is detected more likely in male with ADPKD.
- A.
The answer is E.
Intracranial aneurysm is detected more likely in female with ADPKD.
Identifiable heritable connective tissue disorders contribute to a relatively small percentage of intracranial aneurysms.
Neurosurgical disorders that have been associated with ADPKD include intracranial aneurysms, cervico-cephalic arterial dissections, intracranial dolichoectasia (abnormally dilated and tortuous artery), intracranial arachnoid cysts, spinal meningeal diverticula/cerebrospinal fluid leaks, and chronic subdural hemorrhages.
The presence of polycystic liver disease in patients with ADPKD may also increase the development of intracranial aneurysms.
Patients with ADPLD (autosomal dominant polycystic liver disease) may also be at high risk for the development of intracranial aneurysms.
- 12.
Intracranial aneurysms
Genetics, the FALSE answer is:
- A.
Intracranial aneurysms may be associated with NF type 2.
- B.
An intracranial aneurysm may be the initial manifestation of Ehlers-Danlos syndrome type IV.
- C.
Identifying Ehlers-Danlos syndrome type IV in any patient with an intracranial aneurysm is important because vascular fragility can make any invasive procedure a hazardous.
- D.
In Marfan’s syndrome similar to Ehlers-Danlos syndrome type IV, there is a propensity for proximal intracranial carotid artery involvement.
- E.
Coarctation of the aorta, fibromuscular dysplasia, and pheochromocytoma have been associated with intracranial aneurysms.
- A.
The answer is A.
Intracranial aneurysms may be associated with NF type 1 that often coexist with intracranial arterial occlusive disease, thereby increasing the risk associated with the surgical and particularly endovascular treatment of these aneurysms.
When Ehlers-Danlos syndrome type IV is suspected, collagen type III analysis should be performed on cultured skin fibroblasts to confirm this diagnosis.
- 13.
Intracranial aneurysms
Familial and environmental factors, the FALSE answer is:
- A.
Whites are twice more prone to having aneurysms than the black population.
- B.
7–20 % of patients with aneurysmal SAH had first- or second-degree relatives with intracranial aneurysms.
- C.
Genetic components may predominate in younger patients.
- D.
Environmental components may predominate in the older population.
- E.
Cigarette smoking is not a risk factor for intracranial aneurysms.
- A.
The answer is E.
Cigarette smoking is the most important modifiable environmental risk factor for intracranial aneurysms. Smokers have a three- to tenfold increased risk for aneurysmal SAH.
Those who continue to smoke may be at particularly high risk for the de novo development of aneurysms.
Among first-degree relatives of patients with aneurismal SAH, the risk of a ruptured intracranial aneurysm is approximately four times higher than the risk in the general population.
- 14.
Intracranial aneurysms*
Pediatrics, the FALSE answer is:
- A.
Intracranial aneurysms in childhood account for 1–2 % of intracranial aneurysms.
- B.
They are different from adults in having a female preponderance.
- C.
They are different from adults in that ICA being the most common site.
- D.
They are different from adults in that the MCA bifurcation and the vertebro-basilar system are the second most common site.
- E.
Posterior circulation aneurysms are more common in children than adults.
- A.
The answer is B.
They are different from adults in having a male preponderance.
There is a predominant male/female ratio approaching 2:1–3:1.
The reported incidence is higher in females as compared to males, but Lasjaunias reports that the incidence is higher in males up to 2 years of age and, thereafter, the incidence is higher in females.
- 15.
Intracranial aneurysms*
Pediatrics, the FALSE answer is:
- A.
They are different from adults in having a lower incidence of infective, traumatic, and giant aneurysms.
- B.
The clinical presentation of mass effect or subtle cognitive dysfunction occurs more often than in adults.
- C.
Presenting symptoms are rather due to the mass effect of the aneurysm than due to aneurysm rupture.
- D.
Vasospasm associated with hemorrhage is usually well tolerated in the pediatric age group with a relatively low incidence of ischemic deficits.
- E.
Surgery is usually better tolerated in young children than in adults.
- A.
The answer is A.
They are different from adults in having a HIGHER incidence of infective, traumatic, and giant aneurysms.
Children withstand surgery better than adults due to greater brain functional capacity and better vascular status.
These patients tend to have lesser incidence of clinical vasospasm and appear to have a better outcome as compared to adults.
- 16.
Intracranial aneurysms
General presentation of unruptured intracranial aneurysm, the FALSE answer is:
- A.
Incidental/asymptomatic or minor hemorrhage (sentinel bleed)
- B.
CN III palsy or trigeminal neuralgia or visual loss
- C.
Seizures (most commonly due to ACA aneurysm)
- D.
Headache or migraines (retro-orbital) or endocrine disturbance
- E.
Transient ischemic attacks or small infarcts
- A.
The answer is C.
Seizures: 5, 10, and 25 % of patients with ruptured anterior, posterior, and MCA aneurysm, respectively, suffered from epilepsy over the course of many years of follow-up.
CN III palsy: in 9 % of Pcom aneurysms.
Trigeminal neuralgia: usually in V1 or V2 distribution with intracavernous or supraclinoid aneurysms.
Visual loss: ophthalmic, Acom, basilar apex aneurysms.
Endocrine disturbance: due to compression of pituitary stalk or gland by intrasellar or suprasellar aneurysms.
Transient ischemic attacks or small infarcts: due to distal embolization.
- 17.
Intracranial aneurysms
General presentation, the FALSE answer is:
- A.
The most frequent presentation is SAH.
- B.
ICH: occurs in 20–40 %.
- C.
IVH: occurs in 13–28 %.
- D.
SDH: occurs in 2–5 %.
- E.
ICH: occurs more common with aneurysms proximal to the circle of Willis.
- A.
The answer is E.
ICH: occurs in 20–40 % (more common with aneurysms distal to the circle of Willis, e.g., MCA aneurysms).
- 18.
Intracranial aneurysms
Associated IVH, the FALSE answer is:
- A.
Acom aneurysm rupture usually causes IVH in the lateral ventricle.
- B.
Acom aneurysm rupture usually causes IVH in the third ventricle.
- C.
Distal PICA aneurysms rupture usually causes IVH in the third ventricle.
- D.
Distal basilar artery aneurysm rupture may cause IVH in the third ventricle.
- E.
Carotid terminus aneurysms rupture may cause IVH in the third ventricle.
- A.
The answer is C.
Distal PICA aneurysms usually rupture directly into the fourth ventricle through the foramen of Luschka.
Acom aneurysm: it has been asserted that IVH occurs from rupture through the lamina terminalis into the anterior third or lateral ventricles; however, this is not always borne out at the time of surgery.
Distal basilar artery or carotid terminus aneurysms: may rupture through the floor of the third ventricle (rare).
IVH occurs higher in autopsy series and appears to carry a worse prognosis (64 % mortality).
The size of the ventricles on admission is the most important prognosticator.
- 19.
Intracranial aneurysms
Hemorrhage location in correlation with aneurysm origin, the FALSE answer is:
- A.
The frontal horn hemorrhage is related mostly to Pcom aneurysm.
- B.
The interhemispheric fissure or gyrus rectus hemorrhage is related mostly to Acom aneurysm.
- C.
The sylvian fissure hemorrhage is related mostly to MCA or Pcom aneurysm.
- D.
The prepontine or interpeduncular cistern hemorrhage is related mostly to basilar tip or SCA aneurysm.
- E.
The prepontine or interpeduncular cistern hemorrhage is sometimes related to perimesencephalic nonaneurysmal SAH.
- A.
The answer is A.
The frontal horn hemorrhage is related mostly to choroidal aneurysm.
- 20.
Intracranial aneurysms
General oculomotor palsy in intracranial aneurysm, the FALSE answer is:
- A.
Occurs in 9 % of Pcom aneurysm.
- B.
Occurs less commonly with basilar apex aneurysm.
- C.
Diplopia and ptosis are the classic findings of third nerve palsy by Pcom aneurysm.
- D.
Pupil-sparing third nerve palsy is the classic finding of third nerve compression.
- E.
The development of a third nerve palsy in a patient with an unruptured aneurysm is an emergency result from aneurysmal expansion and impending rupture.
- A.
The answer is D.
Non-pupil-sparing third nerve palsy (dilated unreactive pupil) is the classic finding of third nerve compression.
- 21.
Intracranial aneurysms
Findings that may suggest impending aneurysm rupture, the FALSE answer is:
- A.
Progressing cranial nerve palsy
- B.
Increase in aneurysm size on repeat angiography
- C.
Partial thrombosis of the aneurysm
- D.
Beating aneurysm sign
- E.
Minor hemorrhage
- A.
The answer is C.
Partial thrombosis of the aneurysm is not an alarming sign for rupture. IMMINENT ANEURYSM RUPTURE: Findings that may herald impending aneurysm rupture include:
- 1.
Progressing cranial nerve palsy, e.g., development of third nerve palsy with Pcom aneurysm (traditionally regarded as an indication for urgent treatment).
- 2.
Increase in aneurysm size on repeat angiography.
- 3.
Beating aneurysm sign: pulsatile changes in aneurysm size between cuts or slices on imaging (may be seen on angiography, MRA, or CTA).
- 4.
Minor hemorrhage (sentinel bleed) has an average latency of only 11 days between symptom and clinically significant SAH.
- 1.
- 22.
Intracranial aneurysms
Unruptured aneurysms, (5 years cumulative rupture rate), the FALSE answer is:
- A.
2.5 % for 7–12 mm anterior circulation aneurysm
- B.
40 % for 25 mm or more anterior circulation aneurysms
- C.
14 % for 7–12 mm posterior circulation aneurysm
- D.
50 % for 25 mm or more posterior circulation aneurysms
- E.
Higher rupture rate in anterior circulation aneurysms
- A.
The answer is E.
Higher rupture rate in posterior circulation aneurysms.
The prevalence of UNRUPTURED ANEURYSMS has been found to vary considerably from less than 1 % to as high as 9 %.
- 23.
Intracranial aneurysms
Factors associated with rupture, the FALSE answer is:
- A.
Aneurysm characteristics associated with rupture include aneurysm size, location, and multiplicity.
- B.
Patient characteristics associated with rupture include history of hypertension, previous ischemic cerebrovascular disease, smoking, alcohol, and genetic factors.
- C.
Aneurysm growth is unproved relation.
- D.
Symptomatic aneurysms is unproved relation.
- E.
Men may have an increased likelihood for rupture.
- A.
The answer is E.
Women may have an increased likelihood for rupture.
There is an association between the presence of multiple aneurysms and an increased risk for rupture. (The commonest locations for multiple aneurysms are the Pcom and MCA locations.)
Increasing age >50 years has been thought to increase the risk for hemorrhage.
There is a strong association between cigarette smoking and increased prevalence and risk for rupture.
Gender: Women may have an increased likelihood for rupture. In older patients, female rates of subarachnoid hemorrhage are generally 1.5–2.5 times higher than men, and the median age of presentation is later than men. This is largely due to the higher rates of aneurysms in young males.
Ethnicity: the high incidences of aneurysmal SAH reported in Japanese or Finnish patients compared to others.
Also more in winter and more in daytime.
- 24.
Intracranial aneurysms*
Incidence of rupture according to the SIZE, the FALSE answer is:
- A.
Risk for rupture of <5 mm size unruptured aneurysm is 0.5 % (annual risk).
- B.
Risk for rupture of 5–10 mm size unruptured aneurysm is 11.5 % (annual risk).
- C.
Risk for rupture of 5–10 mm size unruptured aneurysm is 1.2 % (annual risk).
- D.
Risk for rupture of >10 mm size unruptured aneurysm is 1.5 % (annual risk).
- E.
Risk for rupture of >15 mm size unruptured aneurysm is 6.1 % (annual risk).
- A.
The answer is B.
Aneurysm size considered to be an important independent variable in the risk for rupture
Risks for unruptured aneurysm of different sizes and categorized aneurysms into six not mutually exclusive groups: <5 mm (annual risk 0.5 %), <7 mm (0.4 %), 5–10 mm (1.2 %), >10 mm (1.5 %), >12 mm (3.9 %), and >15 mm (6.1 %)
- 25.
Intracranial aneurysms*
Factors associated with rupture according to the SITE, the FALSE answer is:
- A.
The Pcom is the commonest site of a ruptured aneurysm in surgical series.
- B.
A calculated annual risk of rupture for posterior circulation aneurysm is 3.3 %.
- C.
A calculated annual risk of rupture for Pcom aneurysm is 2.2 %.
- D.
A calculated annual risk of rupture for Acom aneurysm is 1.8 %.
- E.
A calculated annual risk of rupture for MCA aneurysm is 1.2 %.
- A.
The answer is A.
The Acom is the commonest site of a ruptured aneurysm in surgical series.
Site was an independent variable.
The incidence of rupture located at the basilar bifurcation and Pcom locations appears to have a higher risk for rupture than at other sites. In contrast, aneurysms within the cavernous sinus appear to have a lower likelihood of bleeding.
Calculated annual risks of rupture by site of aneurysm for the general population are as follows: Acom (1.8 %), ICA (including Pcom 1.3 %), ICA (excluding Pcom 1.0 %), Pcom (2.2 %), MCA (1.2 %), cavernous ICA (0.1 %), and posterior circulation (3.3 %) (defined as vertebral artery, basilar artery, and PCA). This is supported by the ISUIA (International Study of Unruptured Intracranial Aneurysms) finding that aneurysms of the posterior fossa had higher rupture rates.
- 26.
Intracranial aneurysms
Factors associated with rupture, according to the SHAPE, the FALSE answer is:
- A.
Neck width, aspect ratio, and bottleneck factor
- B.
Daughter sacs or blebs or surface irregularity
- C.
Aneurysm site to parent artery ratio
- D.
Aneurysm angle to parent artery
- E.
Aneurysm size to parent artery ratio
- A.
The answer is C.
Neck width: a 4-mm threshold has been established as defining the neck of saccular aneurysms as small or large.
Aspect ratio (height/neck width): This parameter is the distance between the neck and the fundus divided by the maximum neck width (sac length, perpendicular to the neck/widest neck width). The larger the ratio value, the longer the aneurysm sac and the greater the likelihood of the aneurysm having ruptured.
Neck to sac width ratio (bottleneck factor): this parameter (widest sac width/widest neck width) is used to define the likely difficulty of endovascular coil embolization. If the ratio equals 1.0 or less, the aneurysm can be described as sessile in shape and unlikely to retain coils. If greater, the sac is broader than the neck and more favorable for endosaccular packing.
Volume orifice ratio (aneurysm volume to orifice), i.e., neck area rather than neck width, is a recently described parameter which correlates with whether an aneurysm has ruptured or not.
Greater than 80 % of aneurysms rupture at the dome.
Rupture occurs most commonly at the fundus (57–64 %), at a portion of the body (17–33 %), and rarely at the neck region (2–10 %).
- 27.
Intracranial aneurysms
Factors associated with outcome after aneurysm rupture, the FALSE answer is:
- A.
Hunt and Hess clinical grade on admission is the most important factor.
- B.
Aneurysm location, time after hemorrhage, gender, age, and hypertension.
- C.
Rebleeding is not an important risk factor for mortality.
- D.
The apolipoprotein E genotype (APOE4) would be expressed more frequently in patients with an unfavorable outcome.
- E.
Smoking is negatively associated with survival after aneurysmal SAH.
- A.
The answer is C.
Rebleeding is strongly correlated with mortality with the rate of rebleeding is highest during the first 24 h then constant at a rate of 1 % per day to 2 % per day over the subsequent 4 weeks.
Smoking is positively associated with survival after aneurysmal SAH.
The risk of rebleeding from Acom aneurysms is increased by the following factors:
- 1.
Gender (females)
- 2.
Aneurysms that point superiorly and have a wide neck
- 3.
History of coma
- 4.
Systemic hypertension
- 5.
Elderly age.
- 1.
The associated risk factors for bleeding from PcomA are different and include:
- 1.
Age
- 2.
Larger aneurysms
- 3.
The presence of clot
- 4.
Vasospasm
- 1.
- 28.
Intracranial aneurysms
General outcome, the FALSE answer is:
- A.
About 40 % of patients with ruptured aneurysms die following the SAH, and about 40 % of survivors rebleed in the first year.
- B.
The rebleed rate in general is about 3 %, and the death is about 2 % per year.
- C.
Severity of the initial SAH is the most important prognostic factor for outcome.
- D.
Patients who undergo surgical treatment of paraclinoid aneurysms usually have very poor outcomes.
- E.
Surgical outcome for ICA aneurysms is generally good.
- A.
The answer is D.
Patients who undergo surgical treatment of paraclinoid aneurysms usually have good or excellent outcomes.
Surgical outcome for ICA aneurysms is generally good, although straightforward cases are no longer treated by surgery, and more complex aneurysms are referred to vascular neurosurgeons.
- 29.
Intracranial aneurysms
General management, the FALSE answer is:
- A.
Now, the management of intracranial aneurysms is based on CTA results, and DSA is requested only in complex aneurysms.
- B.
Current practice suggests treatment of favorable-grade aneurysms within the first 24–48 h after the SAH.
- C.
Poor grade patients (WFNS grades IV and V) must get trial of clipping.
- D.
Routine DSA is done on postoperative day 7–10 to ensure complete obliteration of the aneurysm.
- E.
If the patient shows clinical evidence of vasospasm, then an angiogram is done.
- A.
The answer is C.
Poor grade patients (WFNS grade V and some WFNS grade IV patients) are only treated if they show improvement in SAH grade.
They are allowed to recover in the intensive care unit with optimization of their electrolytes and antiseizure medications and an external ventricular drain if they have hydrocephalus, and they are only treated if they show improvement in SAH grade. If they are not suitable candidates for endovascular coiling, surgical clipping is performed.
- 30.
Intracranial aneurysms
Guidelines for the management of unruptured aneurysm, the FALSE answer is:
- A.
All asymptomatic intradural aneurysms should be treated.
- B.
Asymptomatic intracavernous aneurysms are usually better to be observed.
- C.
Incidental aneurysms with diameters less than 7 mm are usually better to be observed.
- D.
Endovascular treatment should be considered as a treatment option for incidental aneurysms.
- E.
Aneurysms located at the Pcom have higher rupture rates and deserve special consideration for treatment.
- A.
The answer is A.
All symptomatic intradural aneurysms should be treated.
The other guidelines:
Aneurysms found in association with a ruptured lesion and those with diameters larger than 7 mm deserve strong consideration for treatment, especially in young patients.
Aneurysms located at the Pcom and those in the posterior circulation, especially the basilar tip, have higher rupture rates, and therefore deserve special consideration for treatment.
- 31.
Intracranial aneurysms
General management (aneurysm clips), the FALSE answer is:
- A.
Generally, shorter clips have more closing pressure.
- B.
Temporary clips have a closing pressure of 100 mg.
- C.
Fenestrated and the right-angled ones are ideal for larger aneurysms with a broad neck, especially at the ICA and basilar tree.
- D.
The length of the selected clip should be at least 1.5 times the diameter of the aneurysm neck.
- E.
Yasargil clips are cross action clips and popular. Their small shank does not obscure vision.
- A.
The answer is B.
Temporary clips differ from permanent clips with their closing pressure not exceeding 25–40 gm.
As the clip blades flatten the neck, the length of the closed neck will be half of its circumference. Therefore, a 10-mm neck requires at least a 15-mm clip.
Not infrequently, the clip has to be applied without complete visualization of the hidden vessel and repositioned after decompression of the sac and further dissection.
Heifetz clips have broader wings with an internal spring action and are preferred for thin, friable walls by some.
Sugita clips are somewhat similar and come in various angles.
Malleable clips are used less commonly.
- 32.
Intracranial aneurysms
General management (surgery), the FALSE answer is:
- A.
Wide splitting of the sylvian fissure should be performed for all aneurysms in the anterior circulation to minimize brain retraction.
- B.
Sharp dissection of the neck can result in wide tears that are then difficult to seal.
- C.
Either displacement or mobilization of the aneurysm body is usually required to visualize the vessels initially hidden from view.
- D.
When dissecting directly on the aneurysm, sharp dissection is better than blunt dissection.
- E.
Few Acom aneurysms have necks that are ready to be clipped on initial exposure.
- A.
The answer is B.
Blunt dissection of the aneurysm neck can result in wide tears that are then difficult to seal.
- 33.
Intracranial aneurysms
General management; factors that favor surgical clipping, the FALSE answer is:
- A.
MCA bifurcation aneurysms
- B.
Giant aneurysms or symptoms due to mass effect
- C.
Traumatic intracranial aneurysm
- D.
Small aneurysm
- E.
Wide aneurysm neck
- A.
The answer is C.
Giant aneurysms (high recanalization rate with coiling).
Symptoms due to mass effect: clipping may be better than coiling.
Small aneurysm (higher incidence of intraprocedural rupture with coiling).
Other factors favorable for surgical clipping are:
- 1.
Younger age: lower risk of surgery, and lower lifetime risk of recurrence than with coiling.
- 2.
Patients with residual filling of the aneurysm after coiling.
- 1.
- 34.
Intracranial aneurysms
General management; factors that favor coiling, the FALSE answer is:
- A.
Posterior circulation aneurysms
- B.
Inaccessible ruptured aneurysms
- C.
Aneurysm configuration: dome-to-neck ratio of 1:2
- D.
Aneurysm configuration: an absolute neck diameter <5 mm
- E.
Elderly patients (>75 years.) or patients on clopidogrel or poor clinical grade.
- A.
The answer is C.
Aneurysm configuration: dome-to-neck ratio (aka fundus-to-neck ratio 2:1 or more).
Coiling may be considered in cases where there is a failure of attempted clipping, or with aneurysms that are technically difficult to clip (a category that is very vague and varies widely with the experience of the neurosurgeon).
- 35.
Intracranial aneurysms
General complications, cranial nerve injury during surgery, the FALSE answer is:
- A.
Optic nerve injury during paraclinoid aneurysm surgery.
- B.
Oculomotor nerve injury subtemporal approach to the basilar bifurcation.
- C.
Fourth, fifth, and sixth nerve injury during transtentorial approach to the basilar trunk.
- D.
The combined petrosal approach risks damage to the third nerve.
- E.
Lower cranial nerves injury during infratentorial approaches.
- A.
The answer is D.
The combined petrosal approach risks damage to the seventh and eighth nerves.
With the subtemporal approach to the basilar bifurcation, about two-thirds of patients sustain third nerve damage. Most recover fully but in some of those, some damage persists.
The transtentorial approach to the basilar trunk risks damage to the fourth, fifth, and sixth nerves.
Infratentorial approaches may damage the lower cranial nerves, particularly when dissecting and clipping PICA aneurysms. Great care and delicacy are required when retracting these nerves to gain access. Damage can lead to potentially fatal aspiration pneumonia.
Prevention of optic nerve injury during paraclinoid aneurysm surgery: While unroofing the optic canal, the dura covering the optic nerve must not be disrupted by the drill. The field is continuously irrigated using saline in order to avoid thermal injury to the optic nerve.
- 36.
Intracranial aneurysms
General complications, intraoperative rupture, the FALSE answer is:
- A.
The two most common causes of intraoperative rupture soon after initiation of the procedure are retraction of brain lobes and dislocation of the parent vessel.
- B.
Control is obtained via suction and compression of the bleeding site with cottonoids.
- C.
Induced cardiac arrest facilitates quick dissection and application of a pilot clip in case of uncontrolled bleeding.
- D.
If the rupture takes place before completing the dissection, permanent clips must be applied to all visualized vessels.
- E.
If the rupture takes place before completing the dissection, the aneurysm is prepared for pilot clipping under local flow arrest.
- A.
The answer is D.
If the rupture takes place before completing the dissection, temporary clips must be applied to the parent vessels proximally and distally, and the aneurysm is prepared for pilot clipping under local flow arrest.
- 37.
Intracranial aneurysms
Pathobiology, features of intracranial vessels may make them more prone to aneurysm formation than extracranial vessels, the FALSE answer is:
- A.
Fewer elastic fibers in the tunica media
- B.
Fewer elastic fibers in the tunica adventitia
- C.
Very thick external elastic lamina
- D.
Less muscle in the media
- E.
Thinner adventitia
- A.
The answer is C.
No external elastic lamina
- 38.
Intracranial aneurysms*
Pathobiology, the FALSE answer is:
- A.
Infundibulum is a funnel-shaped dilation of a vessel’s origin with a vessel exiting at the apex of the funnel.
- B.
Usually dilation of the takeoff of the ophthalmic branch of the ICA.
- C.
Charcot-Bouchard aneurysms are microaneurysms occurring in the basal ganglia associated with chronic hypertension.
- D.
Oncotic aneurysms may arise from cerebral embolization of neoplastic cells with cardiac myxomas.
- E.
Formation of aneurysms following radiation has been reported after treatment of germinoma and medulloblastoma.
- A.
The answer is B.
Dilation of the takeoff of a branch of the ICA (usually the Pcom) of 3 mm or less is called an infundibulum. Radiologic and autopsy series suggest an incidence of 6–16 %, which increases with older age. The argument about whether this is a pre-aneurysmal phenomenon or not continues, but it is generally accepted that by itself, an infundibulum does not need to be treated.
Charcot-Bouchard aneurysms are microaneurysms occurring in small (<300 μm diameter) vessels primarily in the basal ganglia associated with chronic hypertension.
Oncotic aneurysms may arise from cerebral embolization of neoplastic cells with infiltration of the vessel wall and subsequent aneurysm formation. Thus, the underlying patho-mechanism is quite similar to infectious aneurysms. Subarachnoid or intraparenchymal hemorrhage may result. Neoplastic aneurysms have been reported with cardiac myxoma, choriocarcinoma, and bronchogenic and undifferentiated carcinomas. Treatment consists of resection of the involved segment, if possible, and evacuation of the symptomatic lesion.
Formation of fusiform aneurysms following radiation and radioactive intrathecal gold therapy has been reported after treatment of germinoma and medulloblastoma. These aneurysms are located in the midline or parasellar region and tend to enlarge and rupture.
- 39.
Intracranial aneurysms
Neurodiagnostic studies, the FALSE answer is:
- A.
CT scan is the “gold standard” diagnostic test of aneurysm.
- B.
MRI may help in the diagnosis of subacute SAH when blood has cleared from the CT scan.
- C.
MRA has not replaced DSA but is useful to evaluate giant or complex aneurysms and dissections.
- D.
MRA is useful for partially thrombosed lesions.
- E.
The four-vessel angiography in multiple projections remains the “gold standard” for diagnosis and treatment planning of aneurysm.
- A.
The answer is A.
CT scan is the preferred diagnostic test when a SAH is suspected.
CTA is useful in large ICH and can eliminate the need for conventional DSA in the rapidly deteriorating patient.
MRA is useful for partially thrombosed lesions because the internal lumen dimensions visible on DSA may not accurately reflect the aneurysm’s true size.
- 40.
Intracranial aneurysms
Neurodiagnostic studies, the features can be evaluated via the four-vessel angiography, the FALSE answer is:
- A.
The aneurysm’s vessel of origin
- B.
Aneurysm size, shape, and relationship to parent and adjacent arteries
- C.
Can assess the location of vasospasm
- D.
Can suggest mass effect by adjacent vessel displacement
- E.
The presence of other aneurysms or vascular abnormalities.
- A.
The answer is C.
The four-vessel angiography can assess the presence but not the location of vasospasm.
- 41.
Intracranial aneurysms
Anesthesia (basic principles and goals), the FALSE answer is:
- A.
Anesthesia should be titratable and short acting to permit a prompt controlled wake-up.
- B.
Drugs that reduce CBF or increase ICP should be avoided.
- C.
Hypotension usually is a must at surgery.
- D.
Invasive blood pressure monitoring is necessary in each patient.
- E.
Arterial blood gases should be checked during surgery to maintain PaCO2 levels between 30 and 35 mmHg.
- A.
The answer is C.
Careful blood pressure control is necessary. Normotension usually is preferred at surgery; however, mean arterial blood pressure should be increased by 10–20 % from the baseline if temporary arterial occlusion is applied. Consequently, invasive blood pressure monitoring is necessary in each patient.
Arterial blood gases should be checked during surgery to obtain adequate oxygenation and to maintain PaCO2 levels between 30 and 35 mmHg. Lower levels of PaCO2 may decrease CBF, particularly in patients with vasospasm.
- 42.
Intracranial aneurysms
Maneuvers for intraoperative brain relaxation, the FALSE answer is:
- A.
CSF drainage through an EVD or lumbar drain
- B.
Hypoventilation
- C.
Head positioning
- D.
Osmotherapy
- E.
Pharmacologic metabolic suppression
- A.
The answer is B.
Hyperventilation.
The incidence of injury from brain retraction is estimated at 5 % in intracranial aneurysm procedures.
CSF drainage through an EVD or lumbar drain. Excessive CSF drainage, however, may be associated with complications.
Once the dura is opened, CSF also can be drained when the arachnoid is opened during the initial exposure.
Osmotherapy such as mannitol (0.5–1 g/kg) which may be supplemented with Lasix (10–40 mg). During the initial period (approximately 15 min) of mannitol administration, intravascular volume is increased before urinary output is affected with resultant contracture of the intravascular volume.
While many neurosurgeons and neuro-anesthesiologists give mannitol upon skin incision, this approach can lead to excessive skin and bone bleeding related to the transient expansion of the intravascular volume.
Appropriate anesthetic agents.
Pharmacologic metabolic suppression (e.g., thiopental, propofol).
Head positioning, including head elevation, and ensuring adequate venous drainage (e.g., chin off chest).
The role of hypothermia remains controversial.
- 43.
Intracranial aneurysms
Rhoton’s anatomic principles directing the surgery, the FALSE answer is:
- A.
The parent artery should be exposed proximal to the aneurysm.
- B.
The dissection is carried around the wall of the parent vessel to the origin of the aneurysm.
- C.
The aneurysmal fundus should be dissected before the neck.
- D.
The aneurysmal neck should be dissected before the fundus.
- E.
All perforating arterial branches should be separated from the aneurysmal neck before passing the clip around the aneurysm.
- A.
The answer is C.
- 44.
Intracranial aneurysms
Rhoton’s anatomic principles directing the surgery, the FALSE answer is:
- A.
The bone flap should be placed as low as possible to minimize brain retraction.
- B.
A clip with a spring mechanism that allows it to be removed and repositioned should be used.
- C.
After the clip is applied, the area should always be inspected for kinking or obstruction.
- D.
If an aneurysm has a broad-based neck that will not easily accept the clip, the neck may be reduced by bipolar coagulation.
- E.
The use of endoscope to view the neck and perforating branches is crucial in all cases.
- A.
The answer is E.
An endoscopic view of the neck with angled endoscopes may aid by revealing the position of perforating branches not seen in the view provided by the surgical microscope.
- 1.
The parent artery should be exposed proximal to the aneurysm. This allows control of flow to the aneurysm if it ruptures during dissection. Exposure of the ICA above the cavernous sinus will give proximal control for aneurysms arising at the level of the Pcom or AChA. Exposure of the ICA at the level of the ophthalmic and superior hypophyseal arteries is commonly achieved by removing the anterior clinoid process, the adjacent part of the roof of the optic canal, and the posterior part of the orbital roof to gain access to the clinoid segment of the ICA. An operative plan that permits cervical internal carotid occlusion in the neck, either by balloon catheter or by direct exposure, should be considered if anterior clinoid removal and proximal supraclinoid exposure is unlikely to yield adequate proximal control. The supraclinoid carotid or the pre-aneurysmal trunks of the middle cerebral or anterior cerebral arteries should also be exposed initially to obtain proximal control of MCA and ACA aneurysms. The exposure can be directed laterally from the ICA for MCA aneurysms and medially over the optic nerves and chiasm for Acom aneurysms. For basilar apex aneurysms, control of the basilar artery proximal to the aneurysm can be obtained by following the inferior surface of the PCA or the superior surface of the SCA to the basilar artery and then working up the side of the basilar artery to the neck of the aneurysm. An operative plan that includes proximal balloon may also be considered. There are several operative routes, discussed below, under Operative Approaches that increase the length of basilar artery below the apex that can be exposed.
- 2.
If possible, the side of the parent vessel away from or opposite to the site on which the aneurysm arises should be exposed before dissecting the neck of the aneurysm. The dissection can then be carried around the wall of the parent vessel to the origin of the aneurysm.
- 3.
The aneurysmal neck should be dissected before the fundus. The neck is the area that can tolerate the greatest manipulation, has the least tendency to rupture, and is to be clipped. Unfortunately, it is the portion of the aneurysm that is most likely to incorporate the origin of a parent arterial trunk or perforating vessel. Therefore, dissection of the neck and proximal part of the fundus should be performed carefully, with full visualization, to prevent passage of a clip around the parental arterial trunk or significant perforating branches that arise near the neck of the aneurysm. The dissection should not be started at the dome, because this is the area most likely to rupture before or during surgery.
- 4.
All perforating arterial branches should be separated from the aneurysmal neck before passing the clip around the aneurysm. Before the use of magnification, there was a tendency to keep dissection of aneurysms to a minimum because of the hazard of rupture. The use of magnification has permitted increased accuracy of dissection of the aneurysmal neck and more frequent preservation of the perforating arteries. Thus the risk of occlusion of peri-aneurysmal perforating arterioles that results from placement of a clip on an inadequately exposed aneurysm is greater than the hazard of rupture with microsurgical dissection. Separating perforating arteries from the neck of an aneurysm requires appropriately sized microdissectors. Small spatula dissectors 1- or 2-mm-wide (Rhoton No. 6 or 7) or 40-degree-angle teardrop dissectors are suitable. Separating the perforators, if tightly packed against or adherent to the aneurysm may be facilitated by lowering the blood pressure or by temporary clipping of the parent artery. In other cases, where the middle portion of the body, but not the neck of the aneurysm, can be separated from the perforating arteries, placing a clip around the middle portion will sometimes reduce the width of the aneurysm neck so that the perforators can be separated from the neck before moving the clip to the aneurysm neck. Perforators may also be placed in the open area of a fenestrated clip in some cases where one cannot separate the perforator from the neck. An endoscopic view of the neck with angled endoscopes may aid by revealing the position of perforating branches not seen in the view provided by the surgical microscope.
- 5.
If rupture occurs during microdissection, bleeding should be controlled by applying a small cotton pledget to the bleeding point and concomitantly reducing mean arterial pressure. If this technique does not stop the hemorrhage, temporary occlusion with a clip or occluding balloon can be applied to the proximal blood supply, but only for a brief time.
- 6.
The bone flap should be placed as low as possible to minimize the need for retraction of the brain in reaching the area. Most aneurysms are located on or near the circle of Willis under the central portion of the brain. Cranial-base resection, such as is performed in the orbitozygomatic, anterior petrosectomy, presigmoid, or far-lateral approaches, should be used if it will minimize brain retraction, improve vascular exposure, and broaden the operative angle available for attacking the aneurysm.
- 7.
A clip with a spring mechanism that allows it to be removed, repositioned, and reapplied should be used.
- 8.
After the clip is applied, the area should always be inspected, sometimes with intraoperative angiography, to make certain the clip does not kink or obstruct a major vessel and that no perforating branches are included in it.
- 9.
If an aneurysm has a broad-based neck that will not easily accept the clip, the neck may be reduced by bipolar coagulation. Nearby perforating arteries are protected with a cottonoid sponge during coagulation. The tips of the bipolar coagulation forceps are inserted between adjacent vessels and the neck of the aneurysm and are gently squeezed during coagulation. Short bursts of low current are used, and the tips of the forceps are relaxed and opened between applications of current to prevent them from adhering to the aneurysm and to evaluate the degree of shrinkage.
- 1.
- 45.
Intracranial aneurysms
The main factors influencing craniotomy selection, the FALSE answer is:
- A.
The aneurysm size
- B.
The aneurysm location
- C.
Aneurysm configuration
- D.
The patient’s clinical status
- E.
The patient’s preference
- A.
The answer is E.
Surgeon preference is an important factor not the patient preference.
Of these factors, the type of aneurysm and its configuration most influence what craniotomy is used.
The aneurysm type (e.g., location and size).
Aneurysm configuration and anatomy of the associated vessels and surrounding osseous and neural structures.
- 46.
Intracranial aneurysms
Clear indications for coiling, the FALSE answer is:
- A.
Anterior circulation aneurysms
- B.
Posterior circulation aneurysms
- C.
Multiple aneurysms
- D.
Paraclinoid aneurysms
- E.
Aneurysms with severe vasospasm
- A.
The answer is A.
Other INDICATIONS:
Patients in extremes of age
Giant/serpentine, fusiform, dissecting, mycotic, and pseudo-aneurysms
Blood blister-like aneurysms (Ogawa aneurysms)
Aneurysms with brain AVM
- 47.
Intracranial aneurysms
Limitations of endovascular treatment, the FALSE answer is:
- A.
Tortuosity of neck vessels.
- B.
Renal failure.
- C.
Aneurysmal size.
- D.
Aneurysms with large parenchymal clot may require surgical evacuation and clipping done in the same sitting.
- E.
Non-availability of modern DSA facility.
- A.
The answer is C.
Aneurysmal size is not a real limiting factor.
Tortuosity of neck vessels (stability of arterial access is the primary step for endovascular treatment).
Also the high cost of material is one of the limitations.
- 48.
Intracranial aneurysms
Anterior circulation aneurysm (pterional craniotomy), the FALSE answer is:
- A.
Most anterior and posterior circulation aneurysms can be approached by pterional craniotomy.
- B.
Some Acom aneurysms may require minor modifications as orbitozygomatic approach.
- C.
Carotid-ophthalmic artery aneurysms may require minor modifications as anterior clinoidectomy.
- D.
For aneurysms that involve the proximal ICA, exposure of the cervical ICA is recommended for proximal control.
- E.
Acom aneurysm required more degree of position rotation than MCA aneurysms.
- A.
The answer is E.
The degree of position rotation depends in part on aneurysm location and anatomy with less rotation for an Acom aneurysm and more rotation for some MCA aneurysms.
- 49.
Intracranial aneurysms
Approaches to MCA aneurysms, the FALSE answer is:
- A.
Medial transsylvian approach provides early proximal M1 control.
- B.
Medial transsylvian approach carries high risk of intraoperative rupture when the aneurysm fundus points anteriorly.
- C.
Lateral transsylvian approach is quicker than a medial transsylvian approach.
- D.
Lateral transsylvian approach advantage is the aneurysm’s neck which can be seen before the dome.
- E.
Superior temporal gyrus approach is useful for an associated ICH that requires evacuation.
- A.
The answer is D.
Lateral transsylvian: The disadvantage is the aneurysm’s dome which is seen before the neck and M1. The sylvian fissure is dissected from lateral to medial and so this approach is quicker than a medial transsylvian approach; there is less CSF loss because the basal cisterns are not opened, less retraction, and the transsylvian veins may be better preserved. However, the aneurysm’s dome is seen before the neck and M1. We prefer this approach when the M1 is very long or for an aneurysm that projects forward to obstruct proximal MCA exposure.
Medial transsylvian: The sylvian fissure is opened from medial to lateral, the ICA followed to its bifurcation, and the MCA trunk defined. This approach provides early proximal M1 control and allows perforators off the M1 to be defined. There are two disadvantages: (1) extensive dissection before the aneurysm is reached, and (2) there is a high risk of intraoperative rupture when the aneurysm fundus points anteriorly and adheres to the sphenoid wing.
Superior temporal gyrus: A 2–3-cm incision that extends posteriorly from just behind the anterior sylvian fissure is made in the superior temporal gyrus parallel to the sylvian fissure. This approach is useful when an ICH requires evacuation or for large aneurysms because it allows circumferential access to the aneurysm and exposure of the aneurysm base and neck while the aneurysm can be retracted.
- 50.
Basilar bifurcation (apex) aneurysm
The FALSE answer is:
- A.
A right-sided approach is preferable.
- B.
A left-sided approach is recommended when there is left third nerve palsy.
- C.
A left-sided approach is recommended when there is left hemiparesis.
- D.
When the bifurcation is located more than 1 cm below the level of the posterior clinoids, the best to use is the subtemporal approach.
- E.
Aneurysms located greater than 1 cm above the posterior clinoids cannot be safely exposed through a subtemporal approach.
- A.
The answer is C.
For most basilar bifurcation aneurysms, a right-sided approach is preferable.
A left-sided approach is recommended when there is:
- 1.
Left third nerve palsy and right hemiparesis.
- 2.
A coexistent left-sided anterior circulation aneurysm and both can be repaired through the same craniotomy.
- 3.
A left-sided approach may be optimal with an aneurysm oriented to the left.
- 1.
The relationship between the basilar artery bifurcation, aneurysm, and the clivus and posterior clinoid process is the major factor that influences surgical approach.
When the bifurcation is located more than 1 cm below the level of the posterior clinoids, its view often is obscured when using a pterional transsylvian approach, and so these lesions may be better approached using a subtemporal trajectory, modified if necessary with a medial petrosectomy or division of the tentorium to reach down the clivus.
Lesions at the level of the posterior clinoid and up to 1 cm above the clinoids can be approached using a subtemporal or transsylvian approach. However, the higher the bifurcation is relative to the posterior clinoid, greater temporal lobe retraction is required. Therefore, basilar bifurcation aneurysms located greater than 1 cm above the posterior clinoids cannot be safely exposed through a subtemporal approach and are difficult to reach through a conventional transsylvian or temporopolar approach. Instead, the craniotomy requires modification such as removal of the zygoma or fronto-orbital bone.
- 51.
Intracranial aneurysms
Temporary artery occlusion during surgery, the FALSE answer is:
- A.
Reduce aneurysm fundus pressure
- B.
Improve the safety of aneurysm neck dissection
- C.
Increase the risk of intraoperative rupture
- D.
Help to reduce the increased morbidity and mortality
- E.
Allow thrombectomy and aneurysmorrhaphy.
- A.
The answer is C.
Reduce the risk of intraoperative rupture.
Temporary occlusion should be kept to a minimum but appropriate use of temporary artery occlusion is an important adjunct during aneurysm surgery.
Temporary occlusion of the proximal arteries during surgery will, in most instances, reduce aneurysm fundus pressure. This may improve the safety of aneurysm neck dissection and reduce the risk of intraoperative rupture or help reduce the increased morbidity and mortality that may be associated with intraoperative aneurysm rupture.
Temporary occlusion also allows thrombectomy, endoaneurysmectomy, and aneurysmorrhaphy to treat giant and complex aneurysms.
- 52.
Intracranial aneurysms
Temporary artery occlusion during surgery, the FALSE answer is:
- A.
The risk of rupture versus ischemia should be balanced.
- B.
Hypotension during temporary occlusion is mandatory.
- C.
Perforating vessels patency must be maintained.
- D.
Safe occlusion time varies with aneurysm location, patient age, and clinical condition.
- E.
Intermittent reperfusion may increase tolerable occlusion time.
- A.
The answer is B.
There are several basic tenets when temporary occlusion is used:
Hypotension during temporary occlusion should be avoided; instead mild hypertension helps collateral flow.
Temporary vessel occlusion should be used selectively and the risk of rupture versus ischemia be balanced.
Perforating vessels patency must be maintained.
Safe occlusion time varies with aneurysm location, patient age, and clinical condition.
Intermittent reperfusion may increase tolerable occlusion time.
Neuroprotection is recommended. When temporary occlusion is planned or thought likely, intraoperative electrophysiological monitors are necessary.
- 53.
Intracranial aneurysms
Temporary artery occlusion during surgery, the FALSE answer is:
- A.
Pharmacologically induced EEG burst suppression is used.
- B.
Mild hypertension is used.
- C.
Hypothermia is frequently induced.
- D.
Barbiturates are the most commonly used agent in aneurysm surgery.
- E.
Total duration of temporary clipping is 45 min.
- A.
The answer is E.
Total duration of temporary clipping is 14 min with 0 % radiographic evidence of cerebral infarction (14–21 min 19 %).
“Neuroprotection” or “cerebral protection” is the use of pharmacologic agents or the manipulation of physiologic parameters to increase resistance to potential damage from temporary focal ischemia. This is best done before occlusion.
The most common strategy is to decrease the metabolic demand typically through pharmacologically induced EEG burst suppression. Mild hypertension, to increase CBF and promote collateral circulation, or hypothermia frequently is induced during temporary occlusion.
Barbiturates are the most commonly used agent in aneurysm surgery.
- 54.
Intracranial aneurysms
Intraoperative rupture, the FALSE answer is:
- A.
SAH increases the risk of rupture.
- B.
Lower initial Hunt and Hess grade increases the risk of rupture.
- C.
Attempted aneurysm occlusion before the aneurysm neck is well defined increases the risk of rupture.
- D.
Sharp dissection increases the risk of rupture.
- E.
Intraoperative rupture can complicate between 5 and 20 % of procedures
- A.
The answer is D.
Sharp dissection decreases the risk of uncontrollable rupture.
Often the consequences of rupture (i.e., size of the hole in the aneurysm) associated with blunt dissection may be worse than sharp dissection.
- 55.
Carotid ophthalmic artery and paraclinoid ICA aneurysms
Operative technique, the FALSE answer is:
- A.
Usually cervical ICA exposure done in patients with a clinoidal ICA aneurysm.
- B.
Remove the lesser wing of sphenoid.
- C.
Remove the ACP (anterior clinoid process).
- D.
Remove the PCP (posterior clinoid process).
- E.
Remove optic strut (OS).
- A.
The answer is D.
Usually cervical ICA exposure done in patients with a clinoidal ICA aneurysm, a complex or giant aneurysm, or aneurysm of the ophthalmic segment.
- 56.
Paraclinoid aneurysms
Anatomy, the FALSE answer is:
- A.
Paraclinoid aneurysms are defined as aneurysms arising from the ICA in close proximity to the ACP.
- B.
The clinoidal segment is usually devoid of named arterial perforators.
- C.
Paraclinoid aneurysms are classified according to the segment of origin into clinoidal or ophthalmic segment types.
- D.
The clinoidal segment is located above and laterals to the ACP.
- E.
The ophthalmic segment is located above and medial to the ACP.
- A.
The answer is D.
The clinoidal segment, the distal portion of the anterior ascending vertical segment of the cavernous carotid artery, is located below and medial to the ACP, above the major venous lumen of the cavernous sinus.
The ophthalmic segment, the distal portion of the paraclinoid ICA region, lies entirely within the subarachnoid space above and medial to the ACP.Related posts:
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