Main

Sir,

Complete third nerve palsy (CTNP) with a fixed and dilated pupil is in most cases the presenting sign of intracranial aneurysm, usually at or near the junction of the internal carotid artery and the posterior communicating artery.1 Intracavernous sinus aneurysms (ICSA) are much less frequent, and typically produce combined oculomotor cranial neuropathies, trigeminal neuropathy, and Horner's syndrome in addition to TNP (nonisolated palsy).1 Acute CTNP because of ICSA is extremely rare, and to the best of our knowledge there are no such reports in the literature.

We present a patient with atypical features of this disorder, who presented with acute angle-closure (AAC) glaucoma and CTNP as presenting signs of thrombosed ICSA.

Case report

A 67-year-old woman presented to the emergency room with a history of headache, left eye pain, and complete ptosis of 2 days duration. Medical history revealed mild hypertension, and left lumpectomy for breast carcinoma 10 years ago. The patient was not previously examined by an ophthalmologist, and no earlier ocular problems were reported. Left eye presented with visual acuity of 6/18, complete ptosis, exotropia, and mild hypotropia (Figure 1). Complete absence of supraduction, infraduction, and adduction was observed. Abduction was normal, and a minor incyclotorsion was noted. There was mild conjunctival congestion, mild corneal epithelial oedema, shallow anterior chamber, 360° closed angle seen by gonioscopy with appositional closure, and a fixed 6 mm dilated pupil nonreactive to light. Intraocular pressure (IOP) was 61 mmHg. Lens was clear, optic nerve head was normal, and retina was flat. In the right eye, visual acuity was of 6/6, with normal anterior and posterior segments, except for a mild shallow anterior chamber; gonioscopy revealed a grade I angle. The patient was treated by p.o. 120 cm3 glycerol, i.v. acetazolamide 500 mg, and pilocarpine 2% drops every 10 min in the left eye for the first 2 h, and then q.i.d., and dexamethasone × 4/day.

Figure 1
figure 1

(Top) complete left ptosis; (Bottom) after manual elevation of upper left eyelid, we can observe left exotropia and hypotropia, and mid-dilated pupil.

Full size image

In the meanwhile, she was referred for immediate neurologic consultation, which was normal, except for the CTNP. The patient underwent computed tomography (CT) without contrast, showing a 2 × 2.5 cm mass in the left cavernous sinus scalloping the sphenoid bone. CT angiography revealed a left cavernous sinus aneurysm mostly thrombosed with small patent lumen extending into the thrombus. Magnetic resonance imaging T1-weighted showed an isointense mass within the cavernous sinus with a small hyperintense lesion corresponding to recent thrombus (Figure 2a). Postgadolinium T1-weighted study demonstrated peripheral and small central enhancement within the cavernous sinus (Figure 2b). Normal flow void was seen in the carotid artery but was absent within the lesion.

Figure 2
figure 2

(a) Sagittal T1-weighted MRI scan without gadolinium, demonstrating a small hyperintense area within the thrombus because of recent haemorrhage. (b) Coronal T1-weighted MRI scan with gadolinium, showing peripheral enhancement of the aneurysm and small patent lumen within the thrombus.

Full size image

At 3 h after treatment initiation, visual acuity in the left eye improved to 6/9, IOP dropped to 14 mmHg, the pupil constricted, and the angle was opened. Eye pain and headache were partially relieved. Neodominium : YAG laser peripheral iridotomy was subsequently performed in both eyes in the following days. After neurosurgical and neuroradiological evaluation, observation only was recommended because of the thrombosis and the low flow within the aneurysm. During the follow-up of 2 months, clinical features remained unchanged.

Comment

ICSA occur predominantly in women in their sixth decade. They represent 2–3% of all intracranial aneurysms, more than 15% of symptomatic aneurysms without rupture, and 20–25% of cavernous sinus lesions. Acute presentation of ICSA is unusual, and their rupture is infrequent (0.5–2%)2 causing carotid–cavernous fistula. Clinical findings are usually because of compression, unlike posterior communicating aneurysms, which can cause a life-threatening subarachnoid haemorrhage. The onset of signs and symptoms of ICSA is usually insidious. The pattern of serial involvement of the cranial nerves within the cavernous sinus is usually as follows: sixth, third, fifth, and fourth. However, acute presentation of ICSA is very rare. The pathogenic mechanism for the acute cranial neuropathies associated with ICSA has not been proven, and is probably because of acute cranial nerve ischaemia from thrombosis or compression of the branches of the intracavernous arteries that supply the cranial nerves during their intracavernous course.3

When an aneurysm compresses the oculomotor nerve, the pupil is usually dilated and reacts poorly to light, because of the injury to the superomedial pupillary fibres along the subarachnoid oculomotor nerve.4 Our patient was predisposed to angle closure because of her anatomically narrow angles. This is a very rare sequence of events. We postulate that acute thrombosis in the aneurysm probably caused acute compression and a rapid mydriasis, precipitating pupillary block. A pupil involving TNP can theoretically produce AAC glaucoma in a predisposed eye, but to the best of our knowledge, there are only two reports in the literature of AAC glaucoma secondary to aneurysm-induced pupil-involving TNP;5,6 none of them described a case of acute CTNP with AAC glaucoma caused by a thrombosed ICSA.

In our patient, scalloping of the adjacent bone was likely produced by a long-standing ICSA. The gold standard to rule out ICSA is cerebral angiography. The diagnosis of ICSA was confirmed by a less invasive and an available method of CT angiography, which showed a partially thrombosed ICSA. This diagnosis was also supported by MRI demonstrating a hyperintense area within the aneurysme because of recent thrombus, which was probably responsible for the presentation of acute CTNP with rapid dilatation of the pupil causing AAC glaucoma.