aCase 14 Answers

by Dr.Chua

This 21-year-old with type 1 neurofibromatosis presents with a four-year history of a right progressive  non-axial painless proptosis and swelling around the orbit (Figure 1A-D). Examination reveals a non-pulsatile exophthalmos. The right eye is only light perception due to corneal scarring from years of exposure keratopathy and possible optic nerve compression. The left eye has normal vision and slit-lamp shows multiple Lisch's nodules.

His past medical history includes three temporal operations for plexiform neurofibroma and a Fasanella Servat operation for right ptosis.

He works as a welder and his main concern is his inability to wear the eye shields to protect his left eye due to the left orbital mass.

Figure 1 Right non-axial proptosis and swelling around the orbit.

a. What are the eyelid abnormalities seen in these pictures?

This patient has orbitoplapebral neurofibromatosis which affects some of the patients with type 1 neurofibromatosis. The condition is progressive and debilitating.

The right eyelids show gross swelling of the eyelid due to diffuse infiltration of the neurofibroma. Palpation of the lesion gives it a 'bag-of-worm' feeling. The lateral and medial canthi are displaced due to orbital dysplasia and progressive exophthalmos.

He is keen for surgical excision of the mass to allow him to wear shield during welding and also to improve his appearance. CT scans of the orbit are shown below.

Figure 2. CT scan of the right orbit.

b. What are the main abnormalities seen in these CT scan?

The CT scan shows ablation of the greater wing of the sphenoid bone. Coronal section reveals the presence of space-occupying masses in the superior and lateral quadrant of the orbit. The optic nerve also appears thickened and may suggest the presence of meningioma.

The absence of greater wing of sphenoid may allow herniation of the temporal lobe into the orbit causing pulsatile exophthalmos. In such cases, neurosurgical intervention is needed to replace the lobe and reconstruct the missing greater wing of the sphenoid.

c. How would you reduce the mass and improve the appearance of this patient?

Surgical treatment of the disease requires a classification of the condition based on an understanding of the underlying pathology. Staged reconstruction is usually needed.

Exophthalmos:

• Protrusion of the globe in this patient is caused by the presence of neurofibromas between the orbital framework and the periorbit. Resection of the tumours may reduce the downward and forward position of the eye.

• In the absence of vision, enucleation can help in restoring a normal appearance. In this patient, the option is discussed but not performed.

The palpebral complex:

• Radical excision of the neurofibromas. The neurofibromas are highly vascular and good haemostasis is essential. In our patient, there is a significant blood loss despite the use of cutting diathermy and blood transfusion is given.

• Following tumour excision, excess lateral skin is excised to reduce the size of the eyelid.

• Lateral and medial canthopexy are performed to reduce restore the lateral and medial canthi.

There is a significant reduction of the proptosis and eyelid swelling following excision of the orbital and eyelid neurofibromas and reconstruction of the medial and lateral canthi. Further reconstruction may be needed to further improve the appearance of the right orbit.

Figure 3. Pictures showing the reconstructive procedures. A. Markings of the right eyelids. B and C Extensive neurofibromas

around the eyelids and the lateral orbit. D. Reconstruction of the lateral canthus via canthopexy. E. Excision of the excess

skin. F. At completion of the procedures.

Figure 4. Appearance of the face at the second post-operative day. The proptosis and eyelid swellings

are significantly reduced. The globe remains displaced downward. The medial canthus has apparent

downward displacement despite medial canthopexy. All these may need addressing at

subsequent reconstruction.

Reference:

1. Jackson, I. T., Laws, E. R., Jr., and Martin, R. D. The surgical management of orbital neurofibromatosis. Plast. Reconstr. Surg. 71: 751, 1983.

2.  Jackson IT, Carbonnel A, Potparic Z, Shaw K. Orbitotemporal neurofibromatosis: classification and treatment. Plast Reconstr Surg. 1993 Jul;92(1):1-11.

3. Lee V, Ragge NK, Collin JR. Orbitotemporal neurofibromatosis. Clinical features and surgical management. Ophthalmology. 2004 Feb;111(2):382-8.