Abstract
We report the case of a 32-year-old woman with bilateral blowout fractures. She presented with diplopia showing impaired abduction of the left eye soon after trauma. No other orbito-ocular signs, such as exophthalmos, ptosis, or chemosis, were found. Orbital reconstruction was performed, but no improvement in her ophthalmoplegia was observed after surgery. A carotid angiography showed that she was suffering from a posteriorly draining carotid-cavernous sinus fistula with isolated abducens nerve palsy. Coil embolization was conducted under the consultation of a neurosurgeon, after which her ophthalmoplegia resolved fully. This is a rare case of posteriorly draining carotid-cavernous sinus fistula without classic orbito-ocular signs, the absence of which may cause diagnostic confusion.
A carotid-cavernous sinus fistula (CCSF) is an abnormally created communication between the carotid artery system and the venous channels of the cavernous sinus. This is an extremely rare phenomenon of cranio-maxillofacial trauma (0.17%) and can result in severe complications, such as permanent visual loss, seizures, fatal epistaxis, and subarachnoid haemorrhage.
In cases of blow-out fractures, ophthalmologic evaluations of visual acuity, ocular motility, pupillary responses, visual fields, and funduscopic examinations are carefully administered. In particular, any diplopia resulting from limited extraocular movement is evaluated to rule out a mechanical entrapment or paresis of the cranial nerves. CCSF is one factor that may lead to neurologic deficits of the III (oculomotor), IV (trochlear), and VI (abducens) nerves. Several cases of ophthalmoplegia due to CCSF have been reported.
CCSF mainly presents the classic triad of chemosis, pulsatile proptosis, and bruit, so-called ‘red-eyed shunt’, which is caused by the disruption of ophthalmic venous return. This aberrant connection is located in the anterior cavernous sinus. Conversely, those occurring at the posterior side of the cavernous sinus do not exhibit any classic congestive orbital signs and are termed ‘white-eyed shunt’. This easily causes diagnostic confusion early in cases of CCSF, and subsequent inappropriate management can lead to fatal conditions. Although the treatment of CCSF is beyond the purview of oral and maxillofacial surgeons, early recognition and an immediate set-up of treatment plans remain crucial for significantly reducing the morbidity related to CCSF. We present a case of blowout fractures with a posteriorly draining CCSF, which featured no orbito-ocular signs except for isolated abducens nerve palsy.
Case report
A 32-year-old woman was brought to the emergency services department of our hospital for injuries she had sustained jumping from her apartment. Computed tomography (CT) demonstrated panfacial fractures with bilateral blowout fractures involving the petrous portion of the temporal bone and sphenoid bone ( Fig. 1 A ). The patient was alert. She was admitted to the intensive care unit for the management of a liver laceration for 9 days and was then transferred to our department for treatment of the panfacial fractures. She complained of diplopia caused by ophthalmoplegia of the left lateral rectus muscle, which did not present immediately after the trauma ( Fig. 1 B). An examination revealed an abduction impairment of her left eye. No ptosis, proptosis, chemosis, or bruit was found. We suspected the possibility of rectus muscle entrapment or temporary injury to cranial nerves, especially the abducens nerve (VI).
Open reduction and internal fixation were performed by the bottom-to-top approach, and the comminuted left orbit was reconstructed with titanium mesh. No evidence of extraocular muscle entrapment or soft tissue engagement was found throughout the surgery, which was confirmed by a forced duction test. However, the patient still complained of diplopia after surgery, and the abduction on the patient’s left side did not improve ( Fig. 2 ). No additional orbito-ocular signs were found.
An ophthalmologic evaluation was performed. No lens dislocation or retinal abnormality was found on funduscopy. Magnetic resonance imaging (MRI) confirmed no engagement or engorgement of the extraocular muscles and soft tissues, however MRI did show asymmetric mild dilatation of the left superior ophthalmic vein and possible CCSF. Following a neurosurgery consultation, a four-vessel digital subtraction cerebral angiogram revealed a type I CCSF on the left side with a distended inferior petrosal sinus ( Fig. 3 ). The patient was diagnosed with a posteriorly draining CCSF with isolated abducens nerve palsy, termed ‘white-eyed shunt’.
