Aneurysmal Subarachnoid Hemorrhage Grading in Animal Models - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 311

injection model ( 5 ). However, not all injection models have been
shown to produce stable clot sizes ( 5 ). The grading system was
originally validated at 24 h after SAH, but has been used success-
fully at time points up to 72 h after SAH ( 14-17 ). At 72 h, a trend
toward smaller SAH grades is observed due to CSF clearing over
time. Ultimately, the duration of time following SAH is a limitation
to the applicability of this system, as animals must be sacrifi ced to be
graded. For long-term studies (weeks to months after SAH), radio-
graphic grading will have to be developed in order to know the
degree of SAH following its induction. Additionally, this system
does not account for the effects of subdural and epidural hemato-
mas that are known to occur with the endovascular puncture model.
It also does not take into account the effects of IVH, which is rec-
ognized as having effects on the incident of vasospasm and out-
comes in clinical studies ( 10 ). The presence or absence of IVH in
the endovascular puncture model in rodents has not been evalu-
ated, and its presence or absence in the validation of this grading
system was not investigated. This scale has also been tested and
proven effective in samples that have undergone transcardiac perfu-
sion of the cerebral vasculature prior to removal of the brain ( 11 ).
Our group also discovered that neurological differences
between SHAM and untreated SAH animals could not be detected
in animals with a mild degree of SAH, grade 0-7 ( 11 ). This also
makes it impossible to determine the effects of therapy in mild
SAH. It is therefore our current practice and recommendation to
exclude these animals from analysis. The unfortunate drawback to
this standardization is that an exclusion rate for the endovascular
perforation model of SAH is now going to be compounded onto a
mortality rate of approximately 40-50%, resulting in a signifi cant
reduction in the number of animals for fi nal analysis at the end of
any given time period. In order to improve upon this exclusion rate
more sensitive neurological testing of animals may need to be
developed or utilized, as slight neurological differences may exist
in mild SAH animals but currently go undetected. The original
validation of this grading system used an adaptation of the Garcia
Neurological Scoring System originally developed for MCA infarc-
tion ( 11, 12 ).

References

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Cortical blood fl ow and cerebral perfusion
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2. Chen J (2008) Animal models of acute neuro-
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