Approach to Internal Carotid Aneurysms

The role of lumbar puncture has declined with the advent of brain imaging. If the CT demonstrates a SAH, there is no need for cerebrospinal fluid (CSF) examination (see Plate 9-39). However, if the diagnosis of SAH is suspected and the CT is negative, CSF evaluation is definitely indicated. When a SAH develops, the CSF becomes bloody and its pressure is often elevated. With centrifugation, the CSF appears xanthochromic; this is an important study component because this finding helps differentiate a true SAH from a traumatic lumbar puncture. In the former, xanthochromia is evident; in the latter, there is no xanthochromia. Additional diagnostic studies include an electrocardiogram, coagulation studies, complete blood count, renal function studies, and electrolytes. These tests are done to screen for comorbid diseases or medical complications of the SAH.

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