Diagnosis and follow-up of carotid-cavernous fistulas by carotid duplex sonography and transcranial color Doppler imaging

Efficacy of Orbital Color Doppler Imaging and Neuroimaging in the Diagnosis of Carotid Cavernous Fistulas

PURPOSE

To evaluate the diagnostic sensitivity and specificity of orbital color Doppler imaging (CDI) and conventional neuroimaging (CT/MRI) compared with cerebral angiography in patients with carotid-cavernous fistulas (CCFs).

METHODS

The study design was a retrospective patient chart and imaging review. The authors reviewed 655 charts of all patients who underwent CDI and neuroimaging (CT/MRI) between 2006 and 2015 at one institution. Sixty patients had a presumptive diagnosis of CCF without thrombosis. Thirty-seven patients with 43 events met the inclusion criteria of the study. The diagnostic sensitivity of the 3 noninvasive imaging modalities (CDI, CT, MRI) for CCF was compared with the gold standard 6-vessel cerebral angiography. Significance testing was performed using the 2-tailed Fisher test.

RESULTS

Color Doppler imaging had high sensitivity (96.8%) but low specificity (41.7%) for the diagnosis of CCFs with anterior orbital findings. A negative CDI had more diagnostic value than a positive CDI. While an arterial wave form in the superior ophthalmic vein was the most common finding of CCF on CDI, enlargement of the superior ophthalmic vein was the only statistically significant finding. Posterior cortical venous drainage was noted in about 10% of the patients with indirect (low-flow) fistulas, who presented with unilateral orbital signs and symptoms, a finding not previously reported in the literature.

CONCLUSION

Color Doppler imaging is a useful noninvasive, radiation-free modality for diagnosis of CCF with anterior drainage, with higher sensitivity than CT or MRI, but equivalent specificity. A significant limitation of CDI is the lack of usefulness in diagnosing fistulas with posterior cortical venous drainage, which carry a risk of intracerebral hemorrhage and stroke. In this series, 10% of unilateral CCFs with anterior orbital signs and symptoms showed angiographic evidence of posterior cortical venous drainage.

Selective Occipital Artery Sonography for Dural Arteriovenous Fistulas

Carotid duplex sonography is a useful method for evaluation of dural arteriovenous fistulas. The resistance index of the external carotid artery has been reported to correlate with the efficacy of treatment and recurrence or aggravation of dural arteriovenous fistulas. Herein, we describe a case of dural arteriovenous fistulas mainly supplied by the occipital artery and show that the resistance index of the occipital artery was more sensitive than that of the external carotid artery. To the best of our knowledge, this is the first report to describe the feasibility of occipital artery detection by carotid duplex sonography and clinical application of the resistance index of the occipital artery for dural arteriovenous fistulas.

Diagnóstico precoz no invasivo de la fístula carótido-cavernosa postraumática por dúplex transcraneal color. Análisis de 4 pacientes

Posttraumatic carotid-cavernous fistula (PtCCF) is an uncommon complication after cranioencephalic trauma. It is usually diagnosed with a cerebral arteriography when the clinical symptoms have already appeared. The transcranial color-coded duplex sonography (TCDS) is a non-invasive technique at the patient's bedside that permits visualization of the circle of Willis and the intracavernous segment of the internal carotid artery. The initial sonographic patterns that suggest the presence of a PtCCF by TCDS are a mosaic image in color mode, presence of arterial and venous flows mixed with high velocity and low resistances. We present our experience in the early and non-invasive diagnosis of PtCFF in an Intensive Care Unit.

Diagnosis of intracranial dural arteriovenous fistulas by carotid duplex sonography

OBJECTIVE

To validate carotid duplex sonography (CDS) in diagnosis of intracranial dural arteriovenous fistulas (AVFs) against the standard of cerebral catheter angiography.

METHODS

We investigated 35 patients with dural AVFs and 64 patients without dural AVFs confirmed by the catheter angiographic studies. Twenty CDS parameters in 4 categories, including resistive index (RI), flow volume, peak systolic velocity, and end-diastolic velocity, were evaluated. Abnormal CDS findings were defined as the data above 95th percentile or below 5th percentile values from 180 control subjects. We determined the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in each CDS parameter.

RESULTS

The parameter of RI of the external carotid artery (ECA; cutoff points: right, 0.72; left, 0.71) yielded the highest sensitivity (74%), specificity (89%), positive predictive value (79%), negative predictive value (86%), and accuracy (84%) for predicting dural AVFs. All other ECA-related parameters yielded sensitivity lower than 70%, and those related to the internal carotid artery were lower than 30%. The sensitivity values for the parameter of RI of the ECA in different locations of dural AVFs were 54% (7 of 13 patients) in cavernous sinus dural AVFs and 86% (19 of 22 patients) in non-cavernous sinus dural AVFs (P = .05).

CONCLUSIONS

The RI of the ECA is the best CDS parameter for predicting intracranial dural AVFs. Carotid duplex sonography can be used as the initial screening tool for diagnosis in patients having symptoms related to dural AVFs.

Transcranial ultrasonography of cerebral veins and sinuses

Transcranial ultrasonography has become a valuable diagnostic tool for the bed-side evaluation of cerebral hemodynamics. While the assessment of arterial blood flow is well established, analysis of venous hemodynamics by transcranial ultrasonography is a new application of the method. The present review summarises the current state of transcranial venous ultrasound in adults by means of transcranial Doppler (TCD) and transcranial colour-coded duplex sonography (TCCS). It gives a critical overview regarding current and possible future clinical applications of the techniques.

Doppler mapping of direct carotid-cavernous fistulae (DCCF)

The aims of this study were to establish Doppler criteria for identifying direct carotid-cavernous fistulae (DCCF), as well as the level of agreement between results obtained by Doppler mapping vs. angiography. Doppler mapping and angiography were used to assess the direction of flow in the superior ophthalmic veins and the resistivity index in the internal carotid arteries of 30 patients with DCCF. Both methods independently demonstrated reverse flow in superior ophthalmic vein ipsilateral to the DCCF in 22 patients and normal flow in another four. The mean resistivity index for internal carotid arteries with ipsilateral DCCF was significantly reduced (p = 0.0001) compared with that for contralateral internal carotid arteries without DCCF. A resistivity index value of 0.495 offered a sensitivity and specificity of 86.6% in diagnosing ipsilateral DCCF. These findings suggest that a resistivity index < 0.495 in the ipsilateral internal carotid artery, with or without reverse flow in the superior ophthalmic vein, is associated with a reasonable probability of diagnosing DCCF.

Carotid and transcranial color-coded duplex sonography in different types of carotid-cavernous fistula

BACKGROUND AND PURPOSE

Patients with carotid-cavernous fistula (CCF) may undergo direct or indirect shunting. Ultrasonography has value that is complementary to angiography in the assessment and follow-up of these patients. The aim of this study was to characterize findings provided by carotid duplex sonography (CDS) and transcranial color-coded duplex sonography (TCCD) in patients with different types of CCF.

METHODS

CDS and TCCD were independently performed by technologists and neurologists. Digital subtraction or MR angiography was interpreted by a neuroradiologist. Ultrasonographic studies were categorized into 4 types: I, direct shunting only; II, direct shunting with a carotid aneurysm; III, indirect shunting only; and IV, mixed (direct and indirect) shunting. In addition to carotid and intracranial flow velocities, volume, and pulsatility, other direct and indirect ultrasound signs of shunting were evaluated. The direct sign of CCF was a mosaic flash detected by TCCD. Alteration of hemodynamic parameters on CDS and demonstration of draining veins with the use of TCCD were considered indirect signs.

RESULTS

Fifteen patients (8 men, 7 women) were included in the study. According to angiographic results, patients in ultrasonographic classification types I (n=7) and II (n=3) corresponded to type A of Barrow's classification. Patients with type III (n=8) were Barrow's type C. Type IV (n=1) had a combination of Barrow's types A and C. On ultrasound, both direct and indirect signs were seen in types I, II, and IV CCF. The presence of a 2-colored oval mass divided by a zone of separation without turbulence differentiated type I from type II CCF. All patients with type III CCF had indirect signs, and only 1 patient had direct signs on TCCD. Abnormal TCCD findings were most commonly seen through the transorbital window (100%), followed by the transtemporal window (63%) and transforaminal window (40%).

CONCLUSIONS

If only indirect ultrasonographic signs of CCF are present, TCCD can be used to predict an indirect CCF type on the basis of the origin of the fistula. With direct communication between carotid artery and cavernous sinus, both direct and indirect ultrasonographic signs can be found. The combination of CDS/TCCD may provide a noninvasive and reliable way to classify patients with CCF.