Aneurysm
- Saccular
Aneurysms
– 85% of nontraumatic SAH (rest from AVM, dissection)
- middle
age, F>M, Pcomm/Acomm/MCA most common, then ICA/basilar/SCA/VBJ/PICA
- Associated
with hypertension, atherosclerosis, FMD, Marfan’s, Ehlers-Danlos,
polycystic kidney disease, AVMs
- Weakening
or ballooning of the wall of a cerebral artery – No internal elastic
lamina
- Associated
with Ehlers-Danlos syndrome, Marfan’s syndrome, polycystic kidney
disease, coarctation/hypoplasia of the aorta, fibromuscular dysplasia
- Overall
prevalence in general population is 2-5%
- Childhood
– M>F, often due to trauma or infection
- Clinical
presentation:
- Subarachnoid
hemorrhage
- Posterior
communicating: headache with third-nerve palsy (does not spare pupil as
diabetic neurophathy)
- Incidentally
seen on imaging for other conditions
- Location:
- 38%
supracavernous carotid (25% Pcomm)
- 36%
anterior circulation (30% Acomm)
- 21%
middle cerebral circulation
- 5%
vertebral/basilar system
- 20%
have multiple aneurysms
- Unruptured
aneurysms have a 0.05-0.5% per year risk of rupture
- Rehemorrhage
rate 20% 2 weeks, 50% 6 months, 3% per year thereafter; does depend on
size of aneurysm; rehemorrhage fatal 50%
- Diagnosis:
angiography
- Treatment:
surgical clipping or endovascular coiling
- Timing
of surgery is dependent on patient’s neurologic status
- Grades
I and II (sometimes III) are generally clipped early (within first 2
days of SAH)
- If
early surgery is not done, then it is advisable to delay surgery until risk
of vasospasm has passed (generally 7-10 days)
- We
usually treat early regardless of grade
- Unruptured
aneurysms are treated electively
- Other
Aneurysm Types
- Fusiform – damage to media
(atherosclerosis, vasculitis, syphilis)
- Older
patients, most often in posterior circulation
- Mycotic – due to embolization of
infected material to intima or vasa vasorum
- 2-3% of
aneurysms
- These
are often multiple and occur in the distal branches (especially of
middle cerebral artery)
- Dissecting
–
nonthrobbing ipsilateral headache
- Often
due to trauma, FMD, cystic medial necrosis, hypertension, migraine,
drugs, pharyngitis, vasculitis, Marfan’s, homocysteinuria
- ICA starts 2 cm above
bifurcation; vertebral starts between C2 and occiput
- Treat
with anticoagulation
- Only
15% will have stroke, but stroke is associated with 25% mortality
- Traumatic – distal ACA
- Oncotic – often due to left atrial
myxoma or choriocarcinoma
- Subarachnoid
Hemorrhage
- “First
or worst” headache – different and worse than ever before; sudden onset
with nausea, vomiting photophobia, lethargy, neck stiffness, and possible
focal neurologic findings
- Other
etiologies of spontaneous SAH: AVM, Hemorrhage into tumor, Vasculitis,
Anticoagulation
- Incidence
is 10-14/100,000 population/year
- Highest
risk of rehemorrhage is during the first 24 hours
- 20-30%
rehemorrhage over first 2 weeks
- Hunt
and Hess Aneurysmal SAH Grading System:
- Grade I
– Asymptomatic or minimal HA and slight nuchal rigidity
- Grade
II – Moderate to severe HA, nuchal rigidity, no neurologic deficit other
than cranial nerve palsy
- Grade
III – Drowsiness, confusion, or mild focal deficit
- Grade
IV – Stupor, moderate to severe hemiparesis, and possible early
decerebrate rigidity and vegetative disturbances
- Grade V
– Deep coma, decerebrate rigidity, moribund appearance
- Diagnosis:
- Uncontrasted
head CT to look for subarachnoid blood (“dead chicken” sign)
- If CT
is negative and history suggestive, an LP must be done
- ALWAYS send tubes 1 and 4 for cell
counts
- CSF
becomes xanthrochromnic within 12 hours of hemorrhage
- Traumatic
taps should clear RBCs between 1st and 4th tubes
- Normal
RBC to WBC ratio is 700:1
- Cerebral
angiogram to document site of aneurysm
- A
4-vessel study is always done since approximately 20% have multiple
aneurysms
- Negative
angios should be repeated in 7-10 days since initial angio might miss
the lesion
- If
clinically suspicious, proceed to angio regardless of CT/LP
- Treatment:
- ICU
monitoring with aneurysm precautions
- Private
darkened room to minimize stimulation
- Visitors
restricted, no television/radio
- No
rectal temps, suppositories, enemas
- Bedrest
(and/or bedside commode is able)
- Load with
anticonvulsant (Dilantin 18 mg/kg, then 300 mg/day)
- Start
Nimodipine 60 mg po/NG q4° x 21 days (reduces risk of vasospasm), Amicar
(epsilon aminocaproic acid) 25 g/250 cc NS at 15 cc/hr IV (or premixed
24 g/96 cc at 6 cc/hr IV) continuous drip until aneurysm is clipped (at
attending’s discretion; antithrombinolytic prevents clot breakdown
around aneurysm)
- Maintain
SBP 140-180 using nipride or NTG drip
- Steroids
will be used at discretion of the attending
- Colace
and prn MOM to prevent constipation
- Vasospasm – Narrowing of cerebral
vasculature frequently associated with subarachnoid hemorrhage
- 4-14
days after rupture – 30% by angio, 20% symptomatic
- Rarely
occurs before day 3 after SAH and usually peaks by day 6-8 after SAH
- Occasionally
can be seen up to 3 weeks after SAH
- Admission
Hunt and Hess grade correlates with risk of spasm
- 20-30%
of grade I and II develop symptomatic vasospasm
- 50-70%
of grade III, IV and V develop symptomatic vasospasm
- Antifibrinolytic
therapy can increase the risk of vasospasm
- One-third
fully recover; one-third have residual deficits, one-third die
- Must be
evaluated urgently to avoid irreversible damage secondary to infarction
- Diagnosis:
- Transcranial
Dopplers show increased velocities
- Uncontrasted
head CT shows no evidence mass lesion or hydrocephalus
- Cerebral
angiography
- Treatment:
- Prevention
measures
- Triple
“H” therapy – induced hypertension, hypervolemia and hemodilution
- Volume
expansion with Swan-Ganz catheter or central line to optimize cardiac
output and cerebral blood flow
- General
goal is to elevate pulmonary wedge pressure to the 12-14 range or CVP
>8
- Care
must be taken to avoid pulmonary edema
- Nimodipine
– calcium channel blocker
- Dose
is 60 mg po q4° for 21 days following SAH
- Some
centers use vasoactive agents to elevate blood pressure if volume
expansion is unsuccessful and patients becomes symptomatic
- Symptomatic
vasospasm
- Intra-arterial
paperverine injection
- Cerebral
angioplasty