214
included in the BRAT study at discharge (91%
versus 67%), at the 1-year follow-up (63% versus
29%), and at the 3-year follow-up (63% versus
32%). They attributed these outcomes to the
location of the aneurysm and hemorrhage rela-
tive to the lower cranial nerves and medulla.
Posterior Cerebral Artery, Superior
Cerebral Artery, and Anterior Inferior
Cerebellar Artery Aneurysms
Aneurysms of the PCA, SCA, and AICA are less
common than their counterparts in the posterior
circulation, and, as such, the results of microsur-
gical treatment involving these aneurysms arise
from smaller case series, most of which include
fewer than 20 patients. For PCA aneurysms, the
results of good outcomes after microsurgical
treatment ranges from 57.1% to 90.9% with mor-
tality rates ranging from 0% to 20% [ 20 , 133 –
139 ]. The treatment of SCA aneurysms similarly
result in good outcomes in 67% to 90% of
pateints, with mortality rates ranging from 0% to
10% [ 20 , 140 , 141 ]. For patients with AICA
aneurysms, good outcomes were achieved in
65% to 100% of patients, with mortality rates
ranging from 0% to 6% [ 20 , 142 – 144 ].
Posterior Fossa Arteriovenous
Malformations
Any discussion of treatment outcomes of cere-
bral AVMs must take into account the recent
results of A Randomized Trial of Unruptured
Brain AVMs (ARUBA), its impact on patient
selection and referral, and its shortcomings [ 145 –
147 ]. A full discussion of the shortcomings of the
ARUBA trial is beyond the scope of this chapter,
but an important point is that, of the 1740 patients
screened, only 726 were deemed eligible and 323
refused enrollment in the trial. Another 177 chose
to have treatment outside of the trial randomiza-
tion process. In addition, the study looked at all
treatments and compared them against medical
management. The widely accepted standard of
treatment for low-grade AVMs, surgery, was used
in only five cases, although 76 patients in the trial
had grade I or II AVMs. When combined with the
very short follow-up of the trial, the results of
ARUBA and its recommendations must be taken
into consideration with great caution.
Drake et al. [ 31 ] reported a series of surgical
treatment of posterior fossa AVMs and demon-
strated that complete resection can be achieved in
most cases (92% in this series), and good out-
comes can be achieved in 71%. The morbidity and
mortality rates in this series were 21% and 15%,
respectively. Other series report good outcomes in
80–91% of patients, morbidity rates of 9–17%,
and mortality rates of 4.1–8.3% [ 30 , 45 , 148 ].Brainstem and Cerebellar Cavernous
MalformationsWith improvements in microsurgical techniques
and surgical tools, including neuronavigation and
microinstruments, surgical resection of cavern-
ous malformations in eloquent regions has
become possible. In a recent report [ 80 ] from our
institution, 260 adults with brainstem cavernous
malformations underwent microsurgical resec-
tion. These patients suffered a new or transient
worsening of their existing deficits in 53% of
cases and permanent deficits were noted in 36%
of patients. More than one-quarter of the patients
(28%) experienced perioperative deficits. The
rate of rehemorrhage after resection was 2% at an
average follow-up of 51 months, and the average
Glasgow Outcome Scale score was 4.6. In this
cohort, 12 patients required reoperation for recur-
rence or residual lesion. The Stanford group
[ 149 ] reported their experience with 176 deep-
seated cavernous malformations that included
those in the brainstem and thalamus. Of these,
136 cavernous malformations were in the brain-
stem. They reported new postoperative deficits in
31.2% of patients. At follow-up, however, the
majority (61.8%) had improved, and 11.2% had
worsened. Li et al. [ 150 ] reviewed their experi-
ence with 242 cavernous malformations of the
brainstem. They noted that 95% of patients
achieved complete resection, and 46.3% of
patients suffered postoperative deficits. At a mean
of 89.4 months of follow-up, the majority of
patients (60.7%) had improved. They calculated
a postoperative annual hemorrhage rate of 0.4%.
The mean modified Rankin Scale score at lastM.Y.S. Kalani and R.F. Spetzler