DAVF (Intracranial dural arteriovenous fistula) is thought to be an acquired arteriovenous (AV) shunting disease, perhaps developing after venous sinus occlusion. DAVF is categorized as benign or aggressive depending on the pattern of venous drainage revealed by digital subtraction angiography.
DAVF is connection between the meningeal arteries and veins. The following areas are the main site; lateral sinus, cavernous sinus, and sigmoid sinus. Some studies of intracranial vascular malformations showed 10-15% as DAVF. Their age presentation is between 40 to 60 years (7). It is accepted and agreed upon that DAVFs are acquired presenting later in life than AVMs (Arterio venous Malformations).(12) Brain tumor surgery, head injuries, or brain infection could be complicated with DAVF. Many neurologic symptoms may be associated with DAVF. These are secondary to ischemia and hemorrhage. These complications features may rate 3 - 11%.(10,16)
Considerable number of cases present with ear symptoms (pulsatile tinnitus). Some studies showed 2 - 20% of DAVF cases with ear symptoms. (8, 9, 14)
But the majority of DAVFs may remain a symptomatic. There are good reports of cases that have spontaneously resolved. Such findings suggesting higher incidence of DAVF than the reported studies. (11,13)
The signs and symptoms are depending on the location of the fistula which is highly variable (19). Of the common non ophthalmic presentation of DAVFis pulsatile tinnitus and intracranial murmur. Of the ocular symptoms in cases with drainage by the ophthalmic veins are; conjunctival dilated vessels, exophthalmos, visual disturbance, and oculomotor paralysis.(17)
Our case is completely asymptomatic and accidentally discovered on routine eye examination for glasses.
DAVFs often present with the classic clinical findings of proptosis, chemosis, and bruit, but in our case it was asymptomatic and the only finding of investigation was disc swelling without any other signs and symptoms
This case starts in 1995, when a 51-year old man was referred to the eye clinic for bilateral optic disc swelling on a routine exam by an optician. On examination VA was 6/6 in both eyes with no ocular complain by the patient, not even headaches. Examination revealed bilateral disc oedema.
The possibility of BIH was raised. He was fully investigated with MRI scan and also referred to neurology. FFA did show disc leakage. At that point the working diagnosis was idiopathic disc swelling. He was monitored in the eye clinic at various intervals. The patient was asymptomatic and his clinical image remained stable. Vision and fields also remained stable.
In 2012, now at the age of 68 the patient was referred again now with symptoms of tightness in his head. Clinically there was no change in fundoscopy. The visual fields however revealed enlargement of the blind spot in both eyes. Again BIH needed to be excluded.
Patient was referred once again for lumbar puncture and MRA. The opening pressure was now 32 in the LP. The MRA conclusion was of dural venous sinus occlusion on the right side. However a dural AV fistula needed to be excluded.
A new MRA with catheter revealed a torcular dural AV fistula. Endovascular obliteration was performed. Patient was seen again after treatment. The tightness seems to have improved now. The Eye examination finding however is exactly the same. Visual fields are the same with slightly enlarged blind spot.
The most feared complication of a cranial DAVF is brain hemorrhage. It is very important to recognize the typical findings of patients presenting with a DAVF then quickly proceeding with a cerebral angiogram to determine the exact location of the fistula and the appropriate treatment plan.
By diagnosing and treating a DAVF as early as possible, the fatal complications can be averted. DAVFs often present with the classic clinical findings of proptosis, chemosis, and bruit. Treatment of a carotid cavernous DAVF is usually undertaken to protect against ocular and visual complications. Symptoms of DAVFs may be characterized further as either nonaggressive (e.g., tinnitus) or aggressive (e.g., intracerebral, subarachnoid, or subdural hemorrhage and neurologic deficits).(20-21) It may also present with an isolated but persistent or progressive headache, or symptoms and signs of a brain hemorrhage including sudden severe headache.
Imaging by CT, CT angiography (CTA), MRI, and cerebral angiography play an important role in the investigation of patients with DAVFs. For a cranial DAVF, MRI is very helpful in defining the DAVF as CT may show only hemorrhage and not the fistula. The gold-standard for detection and characterization of a DAVF is a cerebral angiography on which a DAVF often appears as a complex vascular abnormality made up of abnormally large and tortuous dural arteries, and a large draining vein.
Before any intervention, a non-enhanced CT must be done to rule out intracranial hemorrhage. Chronic venous congestion produces an area of low density on CT due to edema. Multidetector CTA, because of its rapid acquisition, can now provide high-resolution detail of vascular anatomy and has a temporal advantage over static CT.22
Earlier treatment of DAVFs that have these features is important to prevent complications. The risk of conversion from a benign to an aggressive DAVF is small but repeat angiography is indicated if the clinical picture appears to progress.(23)
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Mr. A. Ibraheim MBChB, DORCS London, DO Dublin, FRCS Ed. FRCS RCPS Glas. FEBO (Europe), FRCOphth (UK), Board (IQ)
Dr. G. Mariatos, Specialty Doctor
A.Ibraheim / Eye Clinic
Barnsley Hospitals NHS Foundation Trust Gawber Rd. Barnsley S75 2EP