Ophthalmologic Manifestations of Cerebral Aneurysms

A SAH usually is a very dramatic event. The cardinal symptom is the cataclysmic onset of an extremely severe headache, often described as absolutely the worst pain the patient has ever experienced (see Plate 9-39). Sometimes the headache is associated with transient loss of consciousness, seizures, or a prolonged period of unresponsiveness. Other symptoms include nausea, vomiting, photophobia, phonophobia, and neck pain. Some patients may appear mildly ill while they are complaining of severe headache. Other patients may appear critically ill. Often, the vital signs are unstable, with an irregular pulse and a volatile blood pressure. Focal neurologic impairments may be subtle, and in most cases, no localizing signs are found. An oculomotor (III) nerve palsy with a nonreacting pupil is the most common and clinically useful diagnostic sign (see Plate 9-41). Other ocular signs include intraocular (subhyaloid) hemorrhages, which are most commonly noted in seriously ill patients. The presence of intraocular hemorrhage in a comatose patient points to the diagnosis of an intracranial hemorrhage and, in particular, a ruptured aneurysm. If the aneurysmal bleed is associated with a large localized hematoma or intracerebral extension of the hemorrhage, the patient may have a paraparesis, hemiparesis, or aphasia. Although nuchal rigidity usually is found, it may take several hours for this sign to appear.

The advent of CT with its current widespread availability has revolutionized the evaluation of patients with suspected SAH; it is an extraordinarily sensitive diagnostic test. It is noninvasive and relatively inexpensive. The study will be abnormal in almost all SAH patients. On rare occasion, a CT scan may not demonstrate a minor hemorrhage, particularly in an alert patient whose hemorrhage is restricted to the posterior fossa or in someone whose hemorrhage occurred days or weeks previously. The interval from SAH until the performance of the test also affects the yield; the scan will show subarachnoid blood in approximately 95% of cases scanned at the day of the event, but the frequency of detection of bleeding drops rapidly after a few days. Besides detecting blood in the subarachnoid space, CT also may demonstrate intraventricular or intracerebral hemorrhage, hydrocephalus, brain edema, or a mass effect. The location and pattern of hemorrhage may be helpful in determining the specific site of the ruptured aneurysm, and these findings may be used to predict the development of vasospasm. Whenever there is neurologic worsening, a second CT scan is indicated to screen for evidence of recurrent hemorrhage.

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