Blood flow alterations in cavernous sinus dural arteriovenous fistula: Optical coherence tomography angiography findings.

Purpose: This case report details the diagnostic process for a patient with an initial diagnosis of scleritis who was unresponsive to typical treatment modalities, culminating in the identification of a cavernous sinus dural arteriovenous fistula (CS-DAVF). The case highlights the role of anterior segment optical coherence tomography angiography (OCTA) in the diagnosis of this vascular anomaly and in monitoring the response to treatment. Observations: A 45-year-old man with persistently elevated intraocular pressure (IOP) and ocular congestion in the left eye was unresponsive to treatment for scleritis. The persistent ocular symptoms and new-onset tinnitus prompted further investigation. Anterior segment OCTA revealed vascular anomalies, and magnetic resonance imaging confirmed a CS-DAVF. The patient underwent endovascular treatment for the CS-DAVF. This intervention led to a significant reduction in IOP in the left eye and the resolution of ocular congestion. Conclusions and importance: This case highlights the diagnostic complexities of ophthalmic symptoms that mimic those of other conditions. Furthermore, it demonstrates the essential role of anterior segment OCTA in the accurate diagnosis and effective management of CS-DAVF and highlights the need for comprehensive diagnostic approaches in ophthalmology.

De novo formation of remote dural arteriovenous fistula following treated cavernous sinus dural arteriovenous fistula.

Background: The development of new dural arteriovenous fistulas (DAVFs) at another location following endovascular treatment of cavernous sinus DAVFs (CSDAVFs) are extremely rare. Our aim is to review cases of de Novo DAVFs that occurred after treatment of CSDAVFs at our institution and those reported in the literature. Methods: We reviewed all cases of CSDAVFs evaluated by 2 experienced neuroradiologists. A literature search was performed using the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines focusing on De Novo DAVFs following the endovascular treatment of cerebrovascular malformations. Addition articles were searched through the reference lists of the included articles. Results: From June 2004 and September 2019., we identified 3 (2.5%) cases of De Novo DAVFs occurred after endovascular treatment or spontaneous obliteration of CSDAVFs from 119 treated CSDAVFs at our institute. Our review yielded 9 articles involving 12 patients with 15 de novo DAVFs, including our 3 patients. The mean age was 55.08 ± 12.9 years (range 43-69), 83.3% were females (n = 10). The new remote DAVFs occurred after endovascular treatment of CSDAVFs in 10 (83.3%) patients. The de novo DAVFs occurred following spontaneous complete regression in 2 (16.7%) patients. All de novo DAVFs developed after complete obliteration of treated CSDAVFs. Conclusion: Sinus thrombosis and elevated venous pressure may play an important role in the pathogenesis of a de novo DAVF formation. In addition, thrombophilic abnormalities and the use of contraceptives may contribute to sinus thrombosis, leading to the development of the second remote DAVF after treatment of CSDAVFs.

Paradoxical worsening of ocular symptoms after transvenous embolization of cavernous sinus dural arteriovenous fistula due to coil-induced perifocal inflammation: A case report.

Ocular symptoms usually completely resolve after successful transvenous embolization of cavernous sinus dural arteriovenous fistulas (CS-dAVFs). Herein, we report a case of CS-dAVF in which sinus packing of the superior ophthalmic vein (SOV) caused coil-induced inflammation in orbital tissue, leading to deteriorating ocular symptoms. A 73-year-old woman presented with right-eye exophthalmos and chemosis. Cerebral angiography demonstrated right CS-dAVF, which retrogradely drained into the right SOV. We conducted sinus packing with coils via the right inferior petrosal sinus, resulting in obliteration of the shunts. One day after sinus packing, right exophthalmos and chemosis progressed, suggesting dAVF recurrence. However, no residual angiographic shunts were observed. Orbital magnetic resonance imaging (MRI) revealed edema in intraorbital tissue and gadolinium contrast enhancement of SOV wall. We presumed that the coils in SOV induced perifocal inflammation at the venous wall and surrounding orbital tissue, leading to aggravation of ocular symptoms. Following steroid therapy for 2 months, ocular symptoms and contrast enhancement on orbital MRI significantly improved without anticoagulant treatment. Posttreatment paradoxical worsening of ocular symptoms could be caused by coil-induced inflammation of the SOV wall near the orbital tissue. Steroid therapy could be effective in reducing orbital inflammatory reactions.

A cavernous sinus dural arteriovenous fistula treated by direct puncture of the superior ophthalmic vein with craniotomy: illustrative case.

BACKGROUND: The authors report a case of symptomatic cavernous sinus (CS) dural arteriovenous fistula (dAVF) that was successfully treated using direct puncture of the superior ophthalmic vein (SOV) with craniotomy. CS dAVF is commonly treated using transvenous embolization (TVE), with the most common access route via the inferior petrosal sinus (IPS). However, this route is sometimes unavailable because of an occluded, hypoplastic, aplastic, or tortuous IPS. The SOV is an alternative, albeit tortuous and long, route to the CS; therefore, direct SOV puncture is occasionally performed. Direct SOV puncture is mostly percutaneous; however, in this case, it was difficult because of subcutaneous SOV narrowing. OBSERVATIONS: As the patient experienced increased intraocular pressure, decreased vision, and eye movement disorders, CS embolization was performed via direct puncture with a craniotomy because of other access difficulties. LESSONS: Several reports have described CS dAVF in patients receiving endovascular treatment via direct SOV puncture using a transorbital approach. However, to the best of the authors' knowledge, this is the first reported case of a CS dAVF treated using TVE with craniotomy. This approach is useful when the SOV cannot be reached intravenously and its distance from the epidermis is long.

Spontaneous complete regression of malignant cavernous sinus dural arteriovenous fistula following partial transarterial embolization with liquid embolic material: Report of two cases.

Background: Spontaneous complete regression of malignant cavernous sinus dural arteriovenous fistulas (CSDAVFs) following partial transarterial embolization is an extremely uncommon phenomenon. The mechanism responsible for this condition remains unclear. Case Description: The authors describe two cases of malignant CSDAVFs (Cognard IIb and V) treated by partial transarterial embolization with liquid embolic agents after unsuccessful transvenous embolization through various routes. Follow-up cerebral angiography in these cases confirmed complete resolution of the fistulas. Conclusion: In our two patients harboring low-flow CSDAVFs with preexisting thrombosis of the cavernous sinus (CS), it is possible that some portions of the liquid embolic materials could migrate into the fistulas, inducing thrombosis within the CS.

Likelihood of spontaneous closure of cavernous sinus dural arteriovenous fistulas based on clinical and radiological findings.

BACKGROUND: Cavernous sinus dural arteriovenous fistula (CSDAVF) is a rare condition that radiologists would encounter in their careers. We aim to describe the clinical and radiological characteristics of this condition, and to provide a management workflow. METHODS: In our retrospective study, we studied 27 patients with CSDAVF from January 2007 to August 2020. Patients with direct cavernous sinus AVFs and patients with incomplete date were excluded. Clinical and radiological data were collected and analyzed. RESULTS: Fourteen patients were conservatively treated with spontaneous resolution while 13 patients had endovascular intervention performed. In the intervention group, seven patients had intra-cranial reflux seen on radiological imaging and six patients had clinical deterioration, hence requiring intervention. Clinically, among our patients, 21 had proptosis, 20 had conjunctiva hyperaemia, 18 had extraocular movement limitation, 13 had raised intraocular pressure, 11 had chemosis, ten had ocular pain, nine had ocular bruit, eight had headache and six had worsening visual acuity. Radiologically, a concurrence was seen between superior ophthalmic vein thrombosis and spontaneous resolution of the CSDAVF, as compared to those who underwent intervention. A paradoxical increase of ocular symptoms was seen despite a decrease of flow or stagnation of contrast in radiological imaging of CSDAVF. CONCLUSIONS: In our study, 52% of CSDAVF closed spontaneously. As deterioration of ocular symptoms in patients with CSDAVF might also reflect spontaneous progressive occlusion, it warrants dynamic vascular imaging to check the status of venous outflow. Patients with CSDAVF with corticovenous reflux or deterioration of visual acuity need more urgent (endovascular) treatment.

Non-invasive angiographic analysis of dural carotid cavernous fistula using time-of-flight MR angiography and silent MR angiography: a comparative study.

BACKGROUND: A non-invasive, reliable imaging modality that characterizes cavernous sinus dural arteriovenous fistula (CSDAVF) is beneficial for diagnosis and to assess resolution on follow-up. PURPOSE: To assess the utility of 3D time-of-flight (TOF) and silent magnetic resonance angiography (MRA) for evaluation of CSDAVF from an endovascular perspective. MATERIAL AND METHODS: This prospective study included 37 patients with CSDAVF, who were subjected to digital subtraction angiography (DSA) and 3-T MR imaging with 3D TOF and silent MRA. The main arterial feeders, fistula site, and venous drainage pattern were evaluated, and the results were compared with DSA findings. The diagnostic confidence scores were also recorded using a 4-point Likert scale. RESULTS: Silent MRA correlated better for shunt site localization and angiographic classification (86% vs. 75% and 83% vs. 75%, respectively) compared to TOF MRA. The proportion of arterial feeders detected was marginally significant for silent MRA over TOF MRA sequences (92.8% vs. 89.5%; P=0.048), though for veins both were comparable. Sensitivity of silent MRA was higher for identification of cortical venous reflux (CVR) (90.9% vs. 81.8%) and deep venous drainage (82.4% vs. 64.7%), while specificity was >90% for both modalities. The overall diagnostic confidence score fared better for silent MRA for venous assessment (P < 0.001) as well as fistula point identification (P < 0.001), while no significant difference was evident with TOF MRA for arterial feeders (P=0.06). CONCLUSION: Various angiographic components of CSDAVF could be identified and delineated by 3D TOF and silent MRA, though silent MRA was superior for overall diagnostic assessment.

Cavernous sinus dural arteriovenous fistula embolized via a rare anastomosis between the facial vein and the superficial temporal vein.

A cavernous sinus dural arteriovenous fistula (CSdAVF) is an abnormal communication between the dural branches of the internal and external carotid arteries and the cavernous sinus. Transvenous embolization is the first choice to resolve CSdAVFs, and various venous access routes have been reported. However, transvenous embolization of a CSdAVF through a rare venous anastomosis between the facial and superficial temporal veins using a quadruple coaxial catheter system is scarce in the literature. A 30-year-old woman presented with a typical triad of CSdAVF that was supplied by the inferolateral and meningohypophyseal trunks and several dural branches of the external carotid artery. CSdAVF was solely draining through the right superior ophthalmic vein to the bilateral facial veins. The right facial vein had a rare anastomosis, with the superficial temporal vein terminating in the external jugular vein. Transvenous targeted embolization of CSdAVF was performed through the right superior ophthalmic vein. The rare anastomosis between the right superficial temporal vein and the right facial vein was used as the access route for CSdAVF. The quadruple coaxial catheter system was effective in overcoming the long and tortuous access route and stabilizing the movement of the microcatheter for target embolization. CSdAVF was successfully embolized with microcoils. This is the first report of a CSdAVF embolized via a rare anastomosis between the facial vein and the superficial temporal vein. A quadruple coaxial catheter system can overcome this unusual access route.

Cavernous sinus dural arteriovenous fistula complicated by hippocampus venous congestion: A case report.

BACKGROUND: Hippocampal venous congestion is a rare complication associated with cavernous sinus dural arteriovenous fistulas (CS-DAVFs). CASE DESCRIPTION: A 74-year-old woman was admitted to the hospital with a swollen left eye. Isolated lesions were found in the left hippocampus and the middle cerebellar peduncle. Cerebral angiography revealed retrograde venous drainage of the bilateral inferior petrosal sinuses from the left CS-DAVF. The patient underwent transcatheter arterial embolization, resulting in complete resolution of the hippocampal lesions and neurological symptoms. CONCLUSION: Hippocampal injury is a rare complication of CS-DAVF. Attentive diagnosis and treatment can effectively prevent adverse consequences.

Transfemoral transvenous embolization through the vein of Trolard and superficial middle cerebral vein for cavernous sinus dural arteriovenous fistula with isolated cortical vein drainage: A case report and literature review.

BACKGROUND: Endovascular treatment may be challenging for cavernous sinus dural arteriovenous fistulas (CSDAVFs) with prominent leptomeningeal drainage without other accessible routes. We report a case of CSDAVF with isolated cortical venous successfully drainage treated by percutaneous transvenous embolization through the vein of Trolard and superficial middle cerebral vein (SMCV). We also review the literature of CSDAVFs treated by transvenous embolization through SMCV with or without combined surgical approach. CASE DESCRIPTION: A 46-year-old woman presented with ocular symptoms and delayed treatment was encountered due to the COVID-19 pandemic. Cerebral angiography showed a CSDAVF (Barrow type D, Borden II, and Cognard II a + b) with isolated cortical vein drainage. Percutaneous transvenous access to the fistula through the inferior petrosal sinus was attempted but failed. Transvenous embolization through the vein of Trolard and SMCV was further attempted, and satisfactory occlusion of the fistula was achieved with detachable coils. This access route was chosen because of the occlusion of other access routes and can obliterate the need for more invasive approach, that is, combined surgical and endovascular approach. Cerebral angiography obtained 6 months following the procedure, confirmed complete angiographic obliteration of the fistula. The patient made an uneventful recovery. CONCLUSION: To avoid invasive combined surgical and endovascular approach, transvenous embolization through the vein of Trolard and SMCV may be another accessible option for treating CSDAVF with isolated cortical venous drainage.

Transvenous Embolization of Cavernous Sinus Dural Arteriovenous Fistula through the Angiographically Occlusive Superior Ophthalmic Vein.

Transvenous embolization (TVE) through the superior ophthalmic vein (SOV) is a useful approach for the treatment of cavernous sinus (CS) dural arteriovenous fistulae (DAVFs). This venous route is usually confirmed by angiography. Herein, we present a case of favorable embolization of the CS DAVF through the angiographically occlusive SOV. A 61-year-old man presented with progressive exophthalmos and hypertonia. The patient was diagnosed with a CS DAVF, and TVE was planned. The first approach through the inferior petrosal sinus was infeasible; therefore, we attempted to approach the fistula through the left facial vein. The microcatheter was easily advanced to the shunt point through the angiographically occlusive SOV. We performed coil embolization, and the CS DAVF was completely obstructed.

Endovascular Treatment of Cavernous Sinus Dural Arteriovenous Fistula via Radial Artery and Median Cubital Vein.

Cavernous sinus dural arteriovenous fistula (CS-DAVF) is an arteriovenous shunt where there is fistulous blood flow from the dural arteries from the internal or external carotid artery into the cavernous sinus. The current mainstay of therapy is endovascular treatment. We present a case of restrictive type of CS-DAVF in a 75-year-old male who presented with right eye symptoms. He was treated with embolisation using trans-radial artery access for angiographic runs and a median cubital vein access navigating into the cavernous sinus for coil deployment. This technique completely avoids the conventional technique of a femoral approach and confines all access to the arm. Therefore, there are less risks and complications associated with an arm access, improves patients' comfort and mobility post procedure. Transradial artery and cubital vein access allows for a safe and convenient alternative technique using the arm as compared with conventional transfemoral approach for treatment of CS-DAVF.

Targeted Transvenous Embolization of Cavernous Sinus Dural Arteriovenous Fistula With Liquid Materials Using a Dual-Lumen Balloon Microcatheter.

We describe a challenging transvenous embolization technique involving a dual-lumen balloon microcatheter (DLBM) and liquid materials for cavernous sinus dural arteriovenous fistula (CSDAVF). DLBM contributed to identifying the shunt point and preventing liquid material leakage to normal venous drainage without treatment-related complications. In a transvenous embolization using liquid materials for CSDAVF complications such as cranial nerve palsy and embolic agent migration into the internal carotid artery due to numerous anastomoses must be considered. The use of angiography during DLBM inflation to characterize the shunt point and DLBM to prevent liquid material leakage to the normal venous drainage might decrease the mass effect due to liquid materials, thereby minimizing the causes of newly occurring cranial nerve palsy. This technique may be helpful for the treatment of CSDAVF in practice, but there is generally a risk in using liquid materials in the cavernous sinus; therefore, further consideration is needed in the future.

Hybrid Surgical and Endovascular Approach via the Contralateral Superficial Middle Cerebral Vein to Occlude Cavernous Sinus Dural Arteriovenous Fistula in a Hybrid Operating Room: A Case Report.

Most cases of cavernous sinus dural arteriovenous fistula (CS-dAVF) are treated via the inferior petrous sinus (IPS) through the transfemoral vein approach, but there are cases where treatment through the superficial middle cerebral vein (SMCV) is required. A hybrid operating room (OR) is useful because it allows for smooth direct surgery and endovascular treatment in a clean surgical field. We herein report a case of simultaneous treatment for CS-dAVF by coil embolization via a contralateral SMCV and middle cerebral artery (MCA) aneurysm by clipping in a hybrid OR. A 68-year-old woman had been suffering from left chemosis and ptosis for 2 months before visiting our hospital. Digital subtraction angiography (DSA) revealed Borden type II and Cognard type II a+b CS dAVF with parenchymal hemorrhaging and an unruptured left M1/M2 junction aneurysm. Since passing through the CS via the femoral vein was unsuccessful, we decided to access the right CS via the left CS through the intercavernous sinus (ICS) via the left SMCV by the pterional approach in a hybrid OR equipped with a multi-axis working system angiography machine. Endovascular treatment via direct cannulation into the contralateral SMCV following craniotomy in a hybrid OR is an optional strategy for treating complicated CS-dAVF.

A case of recurrent cavernous sinus dural arteriovenous fistula arising after superselective shunt occlusion and detected by venous arterial spin labeling.

BACKGROUND: Superselective shunt occlusion (SSSO) for cavernous sinus dural arteriovenous fistula (CSDAVF) avoids the risk of cranial nerve palsy, unlike entire sinus packing, but requires paying attention to recurrence. Distinguishing between true and paradoxical worsening of postoperative ophthalmic symptoms using a less-invasive modality is often difficult. Here, we report a case of true worsening of neuro-ophthalmic symptom by recurrent CSDAVF detected by venous-arterial spin labeling (ASL) on magnetic resonance imaging. CASE DESCRIPTION: A 55-year-old woman with neither contributory medical history nor previous head trauma presented with neuro-ophthalmic symptoms and pulsatile tinnitus. Digital subtraction angiography (DSA) revealed CSDAVF with multiple shunted pouches. She underwent successful transvenous SSSO, but neuroophthalmic symptom worsened after SSSO and venous-ASL revealed increased signal intensity in the right superior orbital vein (SOV). DSA confirmed recurrent CSDAVF and additional transvenous embolization was performed. Neuro-ophthalmic symptoms and venous-ASL hyperintensity on SOV improved postoperatively. CONCLUSION: Venous-ASL is noninvasive and seems useful for detecting true worsening of neuro-ophthalmic symptoms of recurrent CSDAVF.

Transvenous embolization through the ipsilateral deep facial vein: A novel approach route for treatment of a cavernous sinus dural arteriovenous fistula.

The superior ophthalmic vein (SOV) approach through the facial vein is usually preferred for transvenous embolization of a cavernous sinus dural arteriovenous fistula (CS DAVF) when the ipsilateral inferior petrosal sinus is angiographically occluded. However, navigating the microcatheter can sometimes be difficult because of stenosis or tortuous angulation at the junction between the angular vein and SOV. We present a novel transvenous access route to treat a CS DAVF using the ipsilateral deep facial vein through the SOV to reach the cavernous sinus. A 66-year-old woman presented with left-sided chemosis, exophthalmos, and external ophthalmoplegia. Angiography showed a left CS DAVF associated with a dilated SOV and retrograde cortical venous reflux. A dilated drainage vein, which branched from the SOV, ran through the lateral aspect of the orbit and exited the orbit through the inferior orbital fissure. This vein connected with the ipsilateral deep facial vein draining into the facial and internal jugular veins. We performed transvenous embolization via the SOV approach through the deep facial vein and achieved complete obliteration, by placing 3 platinum coils, without complications. Ophthalmic veins may connect with the cavernous sinus and pterygoid plexus, passing through the superior and inferior orbital fissures, respectively. Our case suggests that the deep facial vein may provide access to the SOV through the inferior orbital fissure without passing the difficult tortuous angle between the angular vein and SOV.

Surgical Venous Drainage Disconnection from Cavernous Sinus Dural Arteriovenous Fistula and Ruptured Varix.

BACKGROUND: Cavernous sinus dural arteriovenous fistulas (CS dAVFs) occasionally behave aggressively (e.g., intracranial hemorrhage, venous infarction, seizures) depending on the drainage flow and presence of a collateral route of cortical or basal cerebral venous drainage. When a CS dAVF with aggressive behavior is encountered, a radical cure is required to avoid catastrophic deficits. However, conventional transvenous cavernous sinus (CS) embolization via the inferior petrosal sinus does not always achieve shunt obliteration. We herein report a case of surgical venous drainage disconnection in an 83-year-old woman with a CS dAVF. CASE DESCRIPTION: The patient presented with coma and anisocoria due to intracranial hemorrhage. Because of the patient's critical condition, we had no choice but to perform emergency decompressive craniectomy and hematoma evacuation without detailed preoperative hemodynamic information obtained by digital subtraction angiography. Postoperative digital subtraction angiography showed a CS dAVF with retrograde venous drainage of the deep middle cerebral vein (DMCV) and varix formation in the affected DMCV, causing hemorrhagic episodes. Five days after admission, the patient's neurologic state worsened because of rebleeding from the varix, which had increased in size. The percutaneous transvenous approach failed because of compartmentalization within the CS. Open surgery was performed; the deep vasculature was exposed by the transsylvian approach, and the arterialized DMCV was permanently clipped at its proximal segment with disconnection from the venous varix and fistulous point. Shunt obliteration was successfully achieved. CONCLUSIONS: Surgical venous drainage disconnection from the fistulous point may be an alternative radical therapy for CS dAVFs with aggressive behaviors.

Access-route Visualization Using Ultrasonography and CT Angiography to Predict the Feasibility of Transvenous Embolization via the Facial Vein for Cavernous Sinus Dural Arteriovenous Fistulas.

Objective: Transvenous embolization (TVE) is an effective treatment for cavernous sinus dural arteriovenous fistulas (CS-DAVFs). The facial vein (FV) can be used as an access route for TVE when a trans-inferior petrosal sinus (IPS) approach is difficult. We evaluated the usefulness of combining ultrasonography (US) with computed tomography angiography (CTA) for confirming that the FV is a suitable access route for treating CS-DAVFs. Methods: Trans-FV TVE was planned for five CS-DAVF patients in whom the shunt point was located in the posterior compartment of the CS and anterior venous drainage predominantly occurred via the superior ophthalmic vein (SOV). The anterior drainage route was examined with CTA and US. We reviewed the relationships between preoperative CTA/US findings and the accessibility of CS-DAVFs via the FV. Results: The periorbital and perimandibular drainage pathways were clearly more visible on US than on CTA, and the cervical and thoracic drainage pathways were more visible on CTA than on digital subtraction angiography (DSA). CS-DAVFs were accessible via the FV when (1) the entire drainage pathway could be confirmed on CTA and US, (2) the periorbital and perimandibular pathways were unclear on CTA, but could be confirmed on US, or (3) the FV pathway drained into the internal jugular vein (IJV) or external jugular vein (EJV). On the other hand, TVE was challenging to perform via the FV when (1) the periorbital pathway was unclear on CTA and US, (2) the FV pathway drained into the brachiocephalic vein, or (3) the SOV thrombosed intraoperatively. In all five patients, TVE for CS-DAVFs performed via the FV or IPS was successful. Conclusion: CTA and US are useful for confirming the anterior access route for trans-FV TVE for CS-DAVFs and predicting the feasibility of such treatment. Our findings suggest that CS-DAVFs can be accessed via the FV if the periorbital drainage pathway can be confirmed on US, even if the pathway is unclear on CTA.

Management of two cavernous sinus dural arteriovenous fistulae by direct microsurgical approach and catheterization of the superior ophthalmic vein.

BACKGROUND: In case of cavernous sinus dural arteriovenous fistula, transvenous embolization of the cavernous sinus via the inferior petrosal sinus is generally sufficient. However, when inferior petrosal sinus access is challenging, various alternative approaches have been reported, with corresponding difficulties and risks. CASE REPORTS: We report the management of two cases of life-threatening cavernous sinus dural arteriovenous fistula revealed by a typical cavernous sinus syndrome. Conventional approaches were unsuccessful, and a direct microsurgical approach was performed, with catheterization of the superior ophthalmic vein. This combined approach safely accessed the cavernous sinus, and obtained complete occlusion of the fistulae by Onyx® embolization. CONCLUSIONS: This procedure could be an interesting alternative option in the treatment of cavernous sinus dural arteriovenous fistula when conventional approaches are not possible.