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A man in his 20s presented to us for a second opinion for his diplopia. He had previously been treated with an endovascular coil at another centre for traumatic carotid-cavernous fistula (CCF) following a road traffic accident. Prior to coiling, he had left conjunctival congestion with audible bruit and had required antiglaucoma medications. After coiling with platinum alloy coils, his symptoms resolved immediately, but his left eye became more prominent, with left-gaze horizontal diplopia. Six years after his endovascular treatment, his diplopia worsened. He experienced diplopia in his primary gaze, for which prisms were unhelpful. On examination, his visual acuity was 6/6 in both eyes. An anterior segment examination was unremarkable, with no corkscrew vessels, clear cornea, quiet anterior chamber and normal intraocular pressure bilaterally. Fundus examinations were also unremarkable with a pink, healthy optic disc and normal macula and retinal vasculatures. He had pronounced left eye proptosis with limited left ocular motility in abduction (−4). A prism cover test demonstrated left esotropia of 50Δ in the primary gaze, 25Δ in the right gaze and 70Δ in the left gaze, with 3Δ left hypotropia (figure 1). There was no associated eyelid swelling or inflammation, no thrill and systemic examinations were unremarkable. Blood investigations excluded infective causes, thyroid disease and myasthenia gravis. The full blood count, erythrocyte sedimentation rate, C reactive protein, rapid plasma reagin, hepatitis and retroviral infection test results were normal. A thyroid function test revealed normal T3, T4 and thyroid-stimulating hormone (TSH) levels. The acetylcholine receptor antibody test result was negative. A connective tissue disorder workup revealed normal complement level, and the findings of antinuclear antibody, antineutrophil cytoplasmic antibody and rheumatoid factor tests were negative. A CT of the brain and orbit showed left proptosis and inferior globe displacement due to coiling material within the superior left orbit (figure 2). Digital subtraction angiography demonstrated no CCF recurrence. Densely packed coil materials were seen in the left cavernous sinus and superior ophthalmic vein (figure 3). The patient underwent strabismus surgery, with an augmented Hummelsheim procedure and medial rectus recession for the left abducens palsy, which led to an improvement in his diplopia.
Clinical photographs demonstrating left proptosis with esotropia due to left abducens paresis and slight hypotropia.
A CT scan of the orbit in the axial plane showed (A) left non-axial proptosis with more than half of the globe anterior to the interzygomatic line (dashed line). Anteroinferior displacement of the left globe in the (B) sagittal and (C) axial planes caused by hyperdense coils occupying the dilated, tortuous left superior ophthalmic vein (arrowheads) and cavernous sinus (arrow). Streak artefacts at the base of the skull caused by coils.
Digital subtraction angiography of the left internal carotid artery with (A) an anteroposterior view and (B) a lateral view showed no early opacification of the cerebral veins to suggest evidence or recurrence of CCF but revealed the presence of densely packed coil material in the left cavernous sinus (arrow) and the left superior ophthalmic vein (arrowhead). No vascular malformations, aneurysms or enlarged dural veins were seen. CCF, carotid-cavernous fistula.
Traumatic CCF (Barrow type A) occurs due to a tear in the cavernous segment of the internal carotid artery, which leads to pathological connections between the carotid arterial system and the cavernous sinus.1 Traumatic CCFs are high-flow lesions that require treatment. Serious complications may include massive cortical venous drainage, which may lead to haemorrhagic venous infarction and subarachnoid haemorrhage, or severe epistaxis, which can be fatal. These devastating complications can be prevented with a timely endovascular neurointervention.2 3 Endovascular embolisation is a highly effective, first-line treatment for CCF that can be achieved with detachable platinum coils, silk, liquid embolic agents, detachable balloons and covered stents.4 Cranial nerve palsy is a known complication of endovascular treatment with a favourable prognosis, and spontaneous regression is anticipated. Worsening or the delayed onset of cranial nerve palsy after several years of successful endovascular embolisation is relatively rare.5–9 Our patient developed left proptosis and abducens nerve palsy due to the mass effect of the densely packed coil material. The dorsal meningeal branch of the meningohypophyseal trunk, which supplies the abducens nerve, may be compressed by coils in the cavernous sinus, and this may lead to ischemia of the abducens nerve. A venous infarct of the abducens nerve may also result due to elevated venous pressure after transvenous obliteration.5 The progressive abducens palsy in our patient possibly resulted from the migration of one or more of the overpacked coils to the Dorello canal, which caused abducens nerve compression within the osteofibrous conduit.5 6 However, this is generally difficult to visualise via MRI or CT because of streak artefacts from the coils that obscure the fine details at the base of the skull. This case highlights the potential although rare complications of the space-occupying effect of coiling material in CCF.
Learning points
It is important to rule out carotid-cavernous fistula (CCF) recurrence, pseudoaneurysm and the acquired pathology of ocular motility disorders such as ocular myasthenia gravis and thyroid eye disease in treated patients with worsening diplopia or new visual symptoms.
Despite their effectiveness in treating CCF, densely packed endovascular coils may give rise to immediate and long-term complications.
Acquired proptosis and cranial nerve palsy with ocular motility limitations are potential sequelae of densely packed endovascular coil in the superior ophthalmic vein and the cavernous sinus.
Ethics statements
Patient consent for publication
Footnotes
Contributors RJJT was responsible for preparing the manuscript, which included obtaining the patient consent and conducting the literature search.NAM provided important intellectual content for the discussion and finalised the manuscript before submission.NAB contributed to patient management and manuscript preparation.LSC provided expertise in co-managing the patient and contributed to manuscript editing and review.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.