Evaluation of Dural Arteriovenous Fistulas in Children

Examination

• Neurological assessment: Measure the patient’s head circumference and obtain a fundoscopic exam and a neurologic exam, assessing all cranial nerves.
• Cardiovascular examination: Perform auscultation for bruits on head and neck. Perform a cardiopulmonary exam as well, especially in neonates.
• Ophthalmological consultation if indicated: In patients with carotid-cavernous fistulas, consult ophthalmology to evaluate visual loss and intraocular pressure.

Laboratory Tests

• Standard screening in preparation for contrast studies: Obtain a full blood count, biochemistry and metabolic panel, and coagulation studies in all patients.
• Coagulation studies in preparation for surgery: Request a complete coagulation screen to rule out hypercoagulation disorders. Hypercoagulable states should be ruled out as well.

Radiologic Tests

Ultrasound

• Head ultrasound: In neonates, transfontanelle ultrasonography can sometimes depict the vascular lesion.

CT Scan With and Without Contrast

• Hydrocephalus: CT scans may reveal enlarged ventricular spaces, generally due to venous hypertension.
• Edema: Hypodensities, generally without any particular vascular territory pattern, may be observed on CT images.
• Vascular prominence: Abnormally prominent blood vessels are better seen in CTA and CT venography, with reformatting in different planes.

Radiographic evaluation of a DAVF in a pediatric patient: (A) T2-weighted MRI depicts the DAVF, which appears as flow voids (yellow arrow), prior to embolization. (B) DSA demonstrates a pial feeder (blue arrow), dilated pouch (yellow arrow), and dural venous sinus (white arrow). (C) CTA performed shortly after coil embolization of the DAVF reveals dilated vessels without coil artifact (yellow arrows).

• Infarction: Hypodensities in vascular territories may not follow arterial patterns and might be secondary to venous infarcts.
• Calcifications: Chronic venous hypertension can produce calcifications, which are depicted in CT images as hyperdensities.

MRI With and Without Gadolinium

• Hydrocephalus: MRI may reveal enlarged ventricular spaces, generally due to venous hypertension.
• Edema: T2 and FLAIR sequences are the best sequences to illustrate edema.
• Infarction: Use diffusion-weighted imaging for acute ischemia and FLAIR for chronic ischemia.
• Calcifications: Calcifications may manifest differently in different sequences.
• Abnormal vessels: Hypertrophied feeders, varices, and dilated veins can be seen on MRI. MRA can frequently be used to better image these pathologies.

Initial MRI of the brain in axial plane: Image shows a time-of-flight MRI sequence in axial plane with arrows pointing at dilated cortical veins over the left hemisphere.

• Time-resolved MRA: This modality includes various branded names, including GE TRICKS (Time-Resolved Imaging of Contrast KineticS), Siemens TWIST (Time-resolved angiography With Stochastic Trajectories), Philips 4D-TRAK (4D Time-Resolved Angiography using Keyhole), Hitachi TRAQ (Time-Resolved AcQuisition), and Toshiba Freeze Frame. These sequences are an appealing noninvasive option for children and can be very helpful in identifying the site and type of DAVF (29,30).
• Perfusion MRI: Perfusion MRI can be ordered when available to assess perfusion abnormalities and elucidate AV shunting (various arterial spin labeling [ASL] techniques may be used).

Perfusion MRI: (A and B) MRP performed 1 year prior to partial embolization shows high signal in the dural venous sinus. (C) TOF MRA shows lack of cortical signal. After partial embolization of the DAVF, pulsed ASL revealed bilateral medial parietooccipital changes in flow seen on (D) raw perfusion-weighted and (E) cerebral blood flow images. (F) MRA depicts recruitment of significant cortical venous flow and some pial arterial flow.

Angiography

• Diagnostic procedure of choice: Angiography is the most important diagnostic tool in DAVF. This study shows the connection, generally from the extracranial circulation, with venous sinuses and/or subarachnoid veins. Intracranial branches might also be involved, although less frequently. It is essential to rule out the presence of cortical venous reflux and intracranial varices, which correlate with the risk of clinical manifestation.

Borden type II dural fistula, right ICA injection, AP projection, arterial phase: Arrow indicates the fistula from the artery of Bernasconi and Cassinari to the right transverse sinus.

Nuclear Medicine Tests

• Not necessary: These tests are not employed routinely, as findings do not change management.

Electrodiagnostic Tests

• ECG: In case of heart failure, request an ECG.
• EEG monitoring: EEG monitoring might be indicated in cases of seizure presentation or when having difficulties controlling associated seizures.

Neuropsychological Tests

• Nonemergent cases: Neuropsychological testing might be of value in the stable setting, especially in older children with subtle chronic symptoms or when brain parenchyma involvement is observed on imaging.

Correlation of Tests

• Clinical examination and imaging: Symptomatic children — that is, those presenting with hemorrhage, cardiac failure, neurologic symptoms related to venous hypertension, or disabling bruits — or children with concerning angiographic features, such as cortical venous drainage, should be considered candidates for treatment.