Know what to look for in the case of AVMs

New York-Some cerebrovascular events, such as arteriovenous malformations (AVMs) and aneurysms of the brain, occur far less often than migraines and strokes but nevertheless may present in the ophthalmologist's office. With this type of pathology that has ocular manifestations, the ophthalmologist may be one of the first specialists to examine the patient, and knowing what to look for is of paramount importance.

Mark Kupersmith, MD, explained that an AVM of the brain, rather than a migraine or stroke, may be the cause of a recurrent fortification image on the same side in a patient.

He pointed out that an even less common pathology is an AVM of the dura vessels that drains into the brain. This type of AVM, which constitutes about 12% of all AVMs and is often missed by radiologists, also causes the same type of symptoms as migraines and has a great tendency to bleed.

"Orbital ophthalmic approaches can be very helpful in approaching some vascular malformations, particularly AVMs in the cavernous sinus, by going through the transvenous approach on the ophthalmic vein," noted Dr. Kupersmith, who is director of neuro-ophthalmology, Institute for Neurology and Neurosurgery, Roosevelt Hospital and director of neuro-ophthalmology, New York Eye and Ear Infirmary, both in New York.

Be alert to symptoms Not all AVMs or dural AVMs must be treated, but Dr. Kupersmith advised watching for certain signs and symptoms that should raise suspicions. He provided the example of a 76-year-old woman with borderline glaucoma but unaffected vision. Her MRI study, which was considered normal, showed small black dots that indicated that the dural AVM, which was draining into the orbit, was also draining into the brain. This patient was at increased risk of an intracranial hemorrhage.

"The key from the ophthalmic point of view was that both of the patient's eyes were red. Of all the orbital signs that occur with dural AVMs in the cavernous sinus, bilateral redness of the eyes is an overwhelming risk factor of cortical venous drainage, which causes hemorrhages or venous infarcts," he said. Treatment in this patient did not cure the AVM but stopped the drainage into the brain. The treatment goal in these patients is driven by the risk of the development of a major life-threatening problem.

Aneurysms, the most common of the nonischemic vascular diseases, do not necessarily cause a subarachnoid hemorrhage. Those such as cavernous carotid aneurysms that develop farther down in the cavernous sinus do not hemorrhage and are therefore not life-threatening. In a patient who presents with a third-nerve palsy with pupil sparing, this aneurysm is not life-threatening. However, Dr. Kupersmith pointed out that if the patient presents with a third-nerve palsy and the pupil is abnormal, it is likely that he or she has a compressive lesion. In the latter case, a subarachnoid aneurysm must be ruled out because it is life-threatening.

"Diagnosing aneurysms is controversial because of the need for catheter angiography, especially in elderly patients who may have hypertension or diabetes and are at the highest risk of developing complications from the procedure," he said. Alternative noninvasive diagnostic techniques are magnetic resonance angiography (MRA) and computed tomography angiography (CTA).

An important point when treating a patient who presents with a painful third-nerve palsy is to determine if the neuroradiologist evaluated all the images, that is, all the source images that were used to create the MRA, to rule out the presence of an aneurysm.

Treatment involves passing a catheter into the aneurysm bubble, releasing coils and packing the aneurysm, and excluding the aneurysm from the circulation. In some cases when the coils slip back into the circulation, balloons can be used to remodel the coils to remain only in the aneurysm.

However, not every patient with an aneurysm should be treated with coils. In a patient with rapid onset of visual loss, performing decompression surgery by clipping the aneurysm will restore the vision earlier. When looking at the fundus, look for optic atrophy. If the examination shows a normal fundus, this is compatible with the acute loss of vision and performing decompression surgery is indicated, Dr. Kupersmith explained.

"New technologies are being developed every day that can successfully treat patients with an AVM or aneurysm. It is important to refer the patients, but with the exception of aneurysms, a referral does not have to be made immediately," he said.