Restrictive Strabismus Following Frontotemporal-orbitozygomatic Craniotomy

Abstract

The frontotempotal-orbitozygomatic craniotomy (FTOZ) is a standard approach for large sphenoid wing meningiomas (SWMs). Nevertheless, resection of these tumors is not without ophthalmologic risks. This series presents two patients with acute postoperative restrictive strabismus following tumor resection and orbital wall reconstruction. Forced duction testing and postoperative imaging revealed impingement of the lateral rectus muscle caused by an alloplastic implant and/or residual bone, prompting immediate orbitotomy and restoration of normal extraocular muscle function. This report highlights the intricacies of orbital reconstruction, as well as the need for intraoperative forced duction testing.

Keywords: diplopia; forced duction testing; frontotemporal-orbitozygomatic craniotomy; lateral rectus; orbital reconstruction; restrictive strabismus; sphenoid wing meningioma.

Figure 1. Case 1 with restrictive strabismus after frontotemporal-orbitozygomatic craniotomy for a right sphenoid wing meningioma

On postoperative day one, an exotropia of the right eye in primary gaze is noted, and an inability to adduct the eye beyond the midline is demonstrated in Case 1.

Figure 2. Forced duction testing

Forced duction testing (FDT) is performed by applying topical anesthetic drops to the globe, grasping the muscle at its insertion or the corneo-scleral limbus with toothed forceps and rotating the globe in the direction of restriction. In Case 1, positive FDT is demonstrated by the inability to passively adduct the right eye.

Figure 3. Computed tomography of the orbits in Case 1

Computed tomography of the orbits in Case 1 demonstrates impingement of the right lateral rectus muscle by a residual lip of zygomatic bone on axial image (A, arrow), as well as the alloplastic implant on coronal image (B, arrow).

Figure 4. Case 1 after surgical revision for restrictive strabismus via orbitotomy

In Case 1, the impingement of the lateral rectus muscle by bone and the implant were surgically addressed and at one month the patient is orthotropic in primary gaze with normal extraocular motility.

Figure 5. Computed tomography of the orbits in Case 2

Computed tomography of the orbits in Case 2 demonstrates impingement of the left lateral rectus muscle between the residual zygomatic bone and alloplastic implant on axial image (A, arrow) and coronal image (B, arrow). The axial image highlights the abnormal course of the muscle.