Oculomotor synkinesis: an uncommon sequela of paediatric cavernous sinus thrombosis

Abstract

We report an unusual case of acquired oculomotor synkinesis as a sequela of cavernous sinus thrombosis in a child. A 4-year-old male child presented to our emergency services with sudden onset periorbital swelling with complete ptosis of the left upper eyelid. This was preceded by a febrile episode and a furuncle at the tip of the nose. Computerised axial tomography of the orbit revealed orbital cellulitis in the left eye. The child was started on systemic antibiotics followed by a short course of systemic steroids. MRI of the brain with contrast revealed left cavernous sinus and superior ophthalmic vein thrombosis. Following administration of systemic anticoagulants and antibiotics, the ocular motility and ptosis improved remarkably. However, 6 months post-treatment, the child developed signs of aberrant regeneration of the third cranial nerve (oculomotor synkinesis).

Background

Cavernous sinus thrombosis (CST) is a serious neurological, in addition to, being a morbid condition. However, its incidence has reduced with early diagnosis due to newer imaging techniques and the availability of specific antibiotics.¹ CST is often a complication associated with septic thrombosis of the internal jugular vein, bacterial meningitis, sinusitis, otitis media, dental abscess, facial soft-tissue infections and wasp bites in children.² CST can present with multiple cranial nerve involvement (oculomotor, trigeminal and abducens nerves).³ Oculomotor synkinesis is an uncommon but well-described phenomenon and results as a sequela to trauma, tumours and aneurysm of the posterior communicating artery.⁴ This case report highlights oculomotor synkinesis as a rare sequel of CST with superior ophthalmic vein thrombosis (SOVT), despite prompt treatment.

Case presentation

A 4-year-old boy presented to our clinic with upper eyelid swelling and painful protrusion of the left eye. He was also febrile for 10 days and had a scarred furuncle at the tip of his nose (figure 1a). On examination, the left eye showed mild proptosis with pre-septal oedema of the upper eyelid with a sluggishly reacting pupil (figure 1b, c). The visual acuity and ocular motility could not be assessed as the child was very irritable. On examination, the anterior and posterior segments of both eyes were normal. A provisional diagnosis of orbital cellulitis of the left eye was made. A computerised axial tomography (CAT) scan was advised, which showed radiological signs of left orbital cellulitis with pansinusitis (left>right) (figure 1d, e). The child was administered parenteral antibiotics and steroids for 6 days, following which there was a resolution of the fever and reduction of proptosis and pre-septal oedema (figure 2A). The left eye showed external ophthalmoplegia with a fixed and mid-dilated pupil (figure 2B, C). A contrast-enhanced MRI of the brain and orbit was advised, which showed radiological signs of CST and SOVT (figure 3A, B, C). An opinion was sought from a paediatric neurologist and otolaryngologist. The child was started on intravenous vancomycin and ceftazidime with enoxaparin, following which proptosis reduced further and there was an improvement in the extraocular motility. However, residual ptosis with esotropia was seen 3 months post-treatment. Six months later, the visual acuity using Teller acuity chart of the right eye was 20/250 and the child could fix and follow light with his left eye. Esotropia of 25 prism dioptres (PDs) and hypotropia of 8 PDs was noted along with globe retraction on abduction with narrowing of palpebral fissure height (inverse Duane sign) and lid retraction on downward gaze (pseudo-von Graefe sign) with pupillary constriction on attempted convergence (pseudo-Argyll Robertson pupil) suggestive of aberrant third nerve regeneration or oculomotor synkinesis (figure 4A–D). At this stage, fundus examination showed optic atrophy in the left eye.

Figure 1.

(a) Clinical photograph showing a healed furuncle at the tip of the nose (yellow arrow), (b, c) upper eyelid ptosis with pre-septal oedema with normal anterior segment, (d) coronal and (e) axial sections of computerised axial tomography scan showing iso-hyperdense mass lesion in superomedial area of left orbit with ethmoidal sinusitis (yellow star).

Figure 2.

(A–E) Clinical photographs showing resolved pre-septal oedema with persistent upper eyelid ptosis and complete lack of extraocular motility with a fixed dilated pupil in the left eye.

Figure 3.

MRI images of (A, B) T1-weighted coronal cuts depict hyperintensities in the area of orbital apex (yellow arrow) and cavernous sinus (yellow arrowhead) with (C) post-contrast axial cuts showing expansion of left cavernous sinus along with bulging of its lateral wall and presence of dural enhancement (yellow arrowheads) with presence of proptosis.

Figure 4.

(A–C) Clinical photographs showing esotropia with mild ptosis in the left eye in primary gaze position and globe retraction on abduction in the left eye with palpebral fissure narrowing known as inverse Duane sign, (D) presence of eyelid retraction on downgaze also known as pseudo-von Graefe sign.

Investigations

Initial blood work-up showed leucocytosis with an elevated platelet count and an erythrocyte sedimentation rate of 25 mm/hour. The chest X-ray was normal. A CAT scan showed a heterogeneous hyperdense lesion in the superomedial part of the left orbit, along with lesions suggestive of left ethmoidal and maxillary sinusitis (figure 1D, E). In the presence of non-resolving external ophthalmoplegia with a fixed and mid-dilated pupil, an MRI of the brain with contrast was advised, which revealed expansion of the left cavernous sinus with hyperintense soft tissues. The lateral wall of the left cavernous sinus showed bulging with superior ophthalmic vein distention along with abnormal dural enhancement with the presence of left eye proptosis, suggestive of CST and SOVT (figure 3). An MRI performed post-treatment revealed resolution of CST with opacified and reduced calibre of SOV. While visually evoked potential showed a reduction in amplitude and prolongation of latency in the left eye, it was normal in the right eye.

Treatment

Supportive care in the form of intravenous fluids, antipyretics, broad-spectrum antibiotics and long-term anticoagulants were given. Regular monitoring of vitals along with necessary blood investigations were done.

Outcome and follow-up

There was complete resolution of lid oedema and proptosis with no effect on extraocular motility in the first month of the treatment. There was a gradual improvement in extraocular motility. During the course of treatment, minimal vision improvement was noted post-treatment, from fixing following light to counting fingers close to the face. Six months post-treatment, the signs of aberrant regeneration of third nerve along with esotropia and hypotropia with mild ptosis were noticed which persisted until the last follow-up.

Discussion

There is sparse literature on CST causing neuro-ophthalmic complications in paediatric population. The communication of the cavernous sinus with the facial vein and the superior ophthalmic vein that drains the ‘danger triangle’ of the face, including the medial angle of the eyes, nose and perioral region, is usually involved in CST.¹

CST is often a common sequela to ethmoidal and sphenoidal sinusitis and orbital cellulitis in children.² It has been seen that any case of CST along with SOVT secondary to facial or orbital cellulitis, furuncle or facial acne is mainly due to bacterial invasion of venous sinuses.³ In our patient, a furuncle at the tip of the nose and ethmoid sinusitis were probable causative factors for CST. Our patient developed total external ophthalmoplegia and vision loss as a consequence of CST of the left side. Systemic anticoagulants and antibiotics improved the external ophthalmoplegia, but with the emergence of oculomotor synkinesis. Paradoxical eyelid and eye movements, along with pupillary involvement, were noticed in the form of globe retraction on attempted abduction and reduction of palpebral fissure height (inverse Duane sign), lid retraction on downgaze (pseudo-von Graefe sign) and pupillary constriction on attempted convergence (pseudo-Argyll Robertson pupil).⁴ Imaging in the form of MRI of the brain with contrast with fat suppression sequences is ideal for evaluating the orbital apex and cavernous sinus.⁵

Strabismus and ptosis correction in patients with oculomotor synkinesis is often challenging. Simultaneous correction of strabismus and ptosis can be done by performing the procedure on the contralateral (non-paretic) eye to create fixation duress. Large lateral rectus recession with small medial rectus resection in the non-paretic eye is one of the accepted procedures.⁶ However, ipsilateral medial rectus resection must be avoided. The use of adjustable sutures in such cases would be useful.⁷

CST in children as an acquired cause for oculomotor synkinesis is rare. It is vital in retrospect for neuro-ophthalmologists and neurosurgeons to identify signs of acquired oculomotor synkinesis and rule out cavernous sinus pathology.

Learning points.

• Ethmoidal sinusitis and furuncles in the danger area of the face could lead to life-threatening cavernous sinus thrombosis.

• In orbital cellulitis with external ophthalmoplegia, it is important to look for signs of cavernous sinus thrombosis and intervene early.

• Acquired oculomotor synkinesis can be a sequela of cavernous sinus thrombosis.