Abstract
Purpose: :
Indirect fistulas are usually low-flow fistulas with a reduced arterial blood flow. Retrograde venous drainage through the cavernous sinus into to the superior ophthalmic vein (SOV) is less pronounced than in high-flow fistulas. As a consequence, there is less bruit on auscultation, which makes the diagnosis difficult. Associated findings such as choroidal effusion, which may lead to a shallow anterior chamber and an elevated IOP, are considered to be rare complications.
Methods: :
We report on two patients, where the ultrasound biomicroscopic (UBM) demonstration of choroidal effusion was paramount in diagnosing an indirect carotid-cavernous fistula (CCF). The patients underwent ophthalmological examination including a 50 Hz UBM (Paradigm Medical Industries, Inc, P60TM) to examine the choroidea, the anterior chamber depth and the anterior chamber angle.
Results: :
The 1st patient, a 56-year-old man, presented with chemosis, episcleral injection and proptosis of the right eye (4mm). A diagnostic MRI had been read as consistant with SOV thrombosis, EOP or pseudotumor orbitae. A follow up examination revealed a new shallow anterior chamber OD with a normal IOP of 17mmHg. UBM confirmed the reduced anterior chamber depth of 2.5mm (norm: 2.7mm) and demonstrated annular cilio-choroidal effusion with edema of the ciliary body. An angle closure was suggested by an anterior chamber angle of <20° in all four quadrants, namely 13.8° @12h, 12.2° @3h, 12.7° @6h, 19.3° @9h. This effusion lead to the suspected diagnosis of an indirect CFF which could be confirmed on MRA.The 2nd patient, a 62-year-old man, presented with episcleral injection and proptosis of the right eye (3.5mm). Doppler sonography showed a prominent SOV. Neuroimaging revealed an indirect CCF from an AV-malformation in the cavernous sinus. A follow-up one week after therapeutic embolisation of the fistula revealed a shallow anterior chamber OD, IOP: 21mm. UBM confirmed worsening of the clinical situation with a chamber depth of 1.86 mm, a closed chamber angle of 7.33° @3h, 7.17° @9h, 0 @12h & 6h, secondary to annular cilio-choroidal effusion, which lead to a pseudo-plateau configuration of the iris.
Conclusions: :
Angle-closure secondary to annular cilio-choroidal effusion was found in both patients with indirect CCFs. UBS seems to be an useful non-invasive diagnostic tool to aid in diagnosis and follow-up of patients with indirect CCF. We suggest, that more widespread use of UBM might reveal choroidal effusion in more patients with low flow fistulas and thus help in early diagnosis of this disorder.
Keywords: neuro-ophthalmology: diagnosis • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • choroid