|Year : 2022 | Volume
| Issue : 2 | Page : 549-551
Low-flow carotid-cavernous fistula causing oculomotor nerve palsy – More than meets the eye!
Kowsalya Akkayasamy1, Marushka Aguiar2, S Mahesh Kumar1
1 Neuro Ophthalmology Services, Aravind Eye Hospital, Madurai, Tamil Nadu, India
2 Fellow-Paediatric Ophthalmology, Aravind Eye Hospital, Madurai, Tamil Nadu, India
|Date of Submission||04-Jul-2021|
|Date of Acceptance||27-Nov-2021|
|Date of Web Publication||13-Apr-2022|
Department of Neuro Ophthalmology, Aravind Eye Hospital and Post Graduate Institute of Ophthalmology, Madurai - 625 020, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Isolated oculomotor nerve involvement in a posterior draining CCF is relatively rare. We present the case of a 70-year-old female with complaints of painful left-sided ophthalmoplegia and ptosis. She was detected to have a pupil involving third nerve palsy on the left side. We asked for neuroimaging in the form of MRI and MRA which showed a left-sided low-flow CCF compressing the cavernous and the extra-cavernous portion of the oculomotor nerve. This report stresses the importance of keeping low-flow CCF as a differential diagnosis as early detection can be life-saving.
Keywords: Carotid-cavernous fistula, Oculomotor nerve palsy, Diplopia
|How to cite this article:|
Akkayasamy K, Aguiar M, Mahesh Kumar S. Low-flow carotid-cavernous fistula causing oculomotor nerve palsy – More than meets the eye!. Indian J Ophthalmol Case Rep 2022;2:549-51
|How to cite this URL:|
Akkayasamy K, Aguiar M, Mahesh Kumar S. Low-flow carotid-cavernous fistula causing oculomotor nerve palsy – More than meets the eye!. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 May 18];2:549-51. Available from: https://www.ijoreports.in/text.asp?2022/2/2/549/342901
Though it is well known that there are multiple causes of third nerve palsy with pupillary involvement, the most common cause we think of is an intracranial aneurysm as it is also the most dangerous and life-threatening if undetected. Carotid cavernous fistula is not a very common cause; in particular, low-flow CCF tends to present very insidiously with a white eye which can be missed if not suspected. Especially, if the patient is elderly with a coexistent ischemic illness such as diabetes or hypertension, and if pupils are not checked carefully, we could miss this diagnosis due to its unapparent congestive signs.
| Case Report|| |
A 70-year-old female was referred to our Neuro-Ophthalmology department with complaints of noticing drooping of the right upper eyelid for 15 days following injury from a cow's tail. She had a systemic history of hypertension and hyperlipidemia for 10 years and was on regular treatment. On further questioning, the patient gave a history of right-sided headache and periorbital pain for 3 weeks. There was no history of diplopia.
Ophthalmic examination revealed right-sided partial ptosis, mid-dilated pupil, sluggishly reacting to light, and limited right-sided extraocular movements with impaired adduction, supraduction, and infraduction. Her best-corrected visual acuity was 20/80 in both eyes. IOP was normal. Anterior segment showed immature cataracts in both eyes but was otherwise unremarkable. There was no proptosis, chemosis, conjunctival injection, or eyelid swelling. The left eye was normal [Figure 1].
|Figure 1: A 9-gaze photograph showing ptosis and limitation of adduction, elevation, and depression with intact abduction in the right eye|
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After diagnosing this case as painful, pupil-involving third nerve palsy, we suspected an aneurysm of the posterior communicating artery on the right side and advised neuroimaging MRI and MRA. The neuroimaging revealed a low-flow carotid cavernous fistula compressing the cavernous and extra-cavernous portion of the oculomotor nerve. The patient was referred to a neurosurgeon for further management [Figure 2],[Figure 3],[Figure 4],[Figure 5].
|Figure 3: CCF causing compression of cavernous portion of the oculomotor nerve|
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|Figure 4: CCF causing compression of an extracavernous (intraorbital) portion of the oculomotor nerve|
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The patient followed up with us 3 months later with spontaneous resolution of third nerve palsy. On further questioning, she told us that she had been advised digital subtraction angiography but could not afford it [Figure 6].
|Figure 6: 9 gaze photograph showing resolution of third nerve palsy with full extraocular movements and improvement in ptosis|
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| Discussion|| |
Carotid cavernous fistulas are abnormal shunts that allow blood to flow either directly or indirectly to the cavernous sinus from the carotid artery. Proptosis, chemosis, and orbital bruits are typical signs leading to a diagnosis of CCF,, but symptoms of CCF differ according to the venous drainage site.
Congestive manifestations are seen more with anterior draining fistulas affecting superior ophthalmic vein and are called “red-eye shunts” whereas isolated oculomotor nerve palsy without congestive signs as seen in our case affect mainly the inferior and superior petrosal sinus and are called “white-eye shunts.” Delayed diagnosis and treatment might change the flow direction from a posterior to an anterior drainage CCF. When the shunt drains posteriorly, it is seen that the third cranial nerve is most commonly affected, followed by the sixth and the fourth nerve., This is contrary to sixth nerve involvement first in cavernous sinus involvement as it is the only nerve unprotected in the dural wall.
There are not many cases of low-flow CCFs causing isolated pupils involving third nerve palsies, and they tend to be overlooked. It must be kept as an important differential diagnosis in cases of painful ophthalmoplegia.
| Conclusion|| |
In patients presenting with isolated third nerve palsy without significant ocular congestion, it is important to keep low-flow CCF as a diagnosis in mind. Posterior draining CCF is likely to be misdiagnosed, but it is treatable and early diagnosis is important for prognosis. Early MRI/MRA should be performed as an initial study to rule out the involvement of other causes such as aneurysm. DSA should only be considered if CCF is not previously detected in initial radiography.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]