Journal of Neuro-Ophthalmology, December 2000, Volume 20, Issue 4

Superior Oblique Palsy in a Patient with a History of Perineural Spread from a Periorbital Squamous Cell Carcinoma

A 74-year-old man experienced vertical diplopia. Two years earlier, he was diagnosed with a squamous cell carcinoma of the periorbital frontal skin, with perineural spread involving the ophthalmic division of the right trigeminal nerve and the right facial nerve. The clinical findings were consistent with a right fourth cranial nerve palsy. Computerized tomography and magnetic resonance imaging demonstrated a discrete mass involving the belly of the right superior oblique muscle. An anterior orbitotomy and biopsy demonstrated a mass extending into the belly of the superior oblique muscle. Histology revealed an infiltrating squamous cell carcinoma. The possibility of perineural, direct, or metastatic spread to the superior oblique muscle should be considered in a patient with a history of squamous cell carcinoma of the head and neck. The authors believe this case to be the first report of superior oblique underaction due to involvement of the muscle by squamous cell carcinoma, presumably because of perineural spread. Diagnosis was made possible by neuroimaging and histopathology. There was good short-term resolution of the patient's diplopia after radiotherapy.

Journal ofNeuro- Ophthalmology 20( 4): 240- 241, 2000. 2000 Lippincott Williams & Wilkins, Inc., Philadelphia Superior Oblique Palsy in a Patient With a History of Perineural Spread From a Periorbital Squamous Cell Carcinoma Geoffrey A. Wilcsek, FRACO, Ian C. Francis, FRACS, FRACO, FASOPRS, Catherine A. Egan, FRACO, Ken L. Kneale, FRCPA, Shanel Sharma, BSc ( Med), MB, BS, and Medduma B. Kappagoda, FRACS, FRACO A 74- year- old man experienced vertical diplopia. Two years earlier, he was diagnosed with a squamous cell carcinoma of the periorbital frontal skin, with perineural spread involving the ophthalmic division of the right trigeminal nerve and the right facial nerve. The clinical findings were consistent with a right fourth cranial nerve palsy. Computerized tomography and mag­netic resonance imaging demonstrated a discrete mass involv­ing the belly of the right superior oblique muscle. An anterior orbitotomy and biopsy demonstrated a mass extending into the belly of the superior oblique muscle. Histology revealed an infiltrating squamous cell carcinoma. The possibility of peri­neural, direct, or metastatic spread to the superior oblique muscle should be considered in a patient with a history of squamous cell carcinoma of the head and neck. The authors believe this case to be the first report of superior oblique un­deraction due to involvement of the muscle by squamous cell carcinoma, presumably because of perineural spread. Diagnosis was made possible by neuroimaging and histopathology. There was good short- term resolution of the patient's diplopia after radiotherapy. Key Words: Diagnosis- Perineural spread- Squamous cell carcinoma- Trochlear nerve. Superior oblique palsy is the most common cause of vertical ocular motor palsies in adults ( 1). Metastatic disease is a recognized but rare cause of superior oblique palsy. In humans, carcinomas most commonly arise from skin ( 2), and Australia has the highest incidence of skin cancer in the world ( 3). Perineural spread ( PNS) is a well- recognized compli­cation in patients with squamous cell carcinomas ( SCCs) ( 4). Perineural spread is also a significant prognostic in­dicator because the cranial nerves provide a direct route Manuscript received October 18, 1999; accepted March 23, 2000. From the Ocular Plastics Unit ( GAW, ICF, SS), Prince of Wales Hospital, Randwick, Sydney, Australia; Douglass Hanly Moir Pathol­ogy ( KLK), Sydney, Australia; the Royal Victorian Eye and Ear Hos­pital ( CAE), Melbourne, Australia; and the Department of Ophthalmol­ogy ( MBK), Concord Hospital, Sydney, Australia. Address correspondence and reprint requests to I. C. Francis, FRACS, FRACO, FASOPRS, Suite 1, Malvern Court 16- 18, Malvern Avenue, Chats wood, NSW, Australia 2067. of spread to the brainstem. Tumors that are capable of PNS have a higher incidence of blood- born metastases to distant sites ( 5). A high level of suspicion for PNS may improve the chance of cure with early radical surgery and radiotherapy. However, once the bony foramina have been traversed by the tumor, treatment is largely palliative. CASE REPORT A 74- year- old man had a 1- week history of vertical diplopia. His medical history included multiple excisions of skin cancers from his head and neck. Two years ear­lier, he was diagnosed with PNS from a forehead SCC involving the ophthalmic division of the right trigeminal nerve and the temporal and zygomatic branches of the right facial nerves. On examination, using the Parkes three- step test, a right fourth nerve palsy was diagnosed. There was reduced sensation to pin- prick and light touch in the distribution of the ophthalmic division of the right trigeminal nerve. The muscles supplied by the zygomatic and temporal branches of the right facial nerve were weak. Results of the remainder of the cranial nerve ex­amination were normal. Because of the patient's history of PNS, computerized tomography of the head was performed, and it demon­strated a 1.5- cm discrete mass in the right superomedial orbit, which was indistinguishable from the belly of the superior oblique muscle ( Figs. 1,2.) There was no en­largement of bony foramina. Magnetic resonance imag­ing revealed no centripetal spread of the tumor along the trochlear nerve, into the brainstem, or intracranially. In particular, the cavernous sinus was normal. To obtain a tissue diagnosis, a superomedial anterior orbitotomy was performed and a biopsy was taken. Histopathology dem­onstrated cords of infiltrating SCC ( Fig. 3). The patient subsequently underwent a course of radio­therapy to the region, and there was resolution of his diplopia. Unfortunately, there was recurrence of his or­bital disease and involvement of his cervical lymph nodes. The patient died 3 years later, after a brainstem vascular event. An autopsy was denied. 240 SUPERIOR OBLIQUE PALSY 241 FIG. 1. Coronal computed tomography scan of the orbits dem­onstrates an enlarged right superior oblique muscle ( arrow). DISCUSSION A fourth nerve palsy is the most common cause of vertical ocular motor palsies in adults. It should therefore be suspected in any patient with a vertical deviation and/ or abnormal head posture. However, it is the least preva­lent cause of an isolated ocular motor paralysis ( 6). In a study by Rush and Young ( 7), of 1,000 cases of paralysis of cranial nerves III, IV, and VI, the most common cause of a fourth nerve palsy remained undetermined ( 36%). Other causes included trauma ( 32%), vascular disease ( 18%), neoplasm ( 4%), aneurysm ( 2%), and miscella­neous causes ( 8%). Uncommon reported cases included an arteriovenous malformation of the trochlear nerve ( 6), intracavernous internal carotid aneurysm ( 7), a large bas­ilar aneurysm ( 7), a tentorium cerebelli meningioma ( 8), and a posterior fossa astrocytoma ( 9). Orbital myositis FIG. 2. Axial computed tomography scan demonstrates a mass in the region of the right superonasal orbit ( arrow). FIG. 3. Hematoxylin- and eosin- stained image of nerve with tu­mor cells in surrounding connective tissues ( large arrow), and tumor cells evident within the perineural tissue ( small arrow) ( original magnification, x100). can also involve the superior oblique muscle ( 10). Me­tastasis to extraocular muscles, in particular to the medial rectus, can occur ( 11), as in a case of small cell cancer that metastasized to the medial rectus muscle. However, metastatic disease to the orbit is usually diffusely spread within the orbit, rather than confined to a discrete mass within one extraocular muscle ( 12). Periorbital skin cancers ( 1,2) are the most likely cause of PNS affecting the cutaneous branches of the trigem­inal and facial nerves. Although our patient had a history of PNS of an upper facial SCC to the facial and trigem­inal nerves, the mechanism of the tumor reaching the superior oblique muscle is uncertain. The possibilities include direct, metastatic, or PNS of the SCC. REFERENCES 1. Ozkan SB, Aribal ME, Sener EC, et al. Magnetic resonance im­aging in evaluation of congenital and acquired superior oblique palsy. J Pediatr Ophthalmol Strabismus 1997; 34: 29- 34. 2. Hayat G, Ehsan T, Selhorst JB, et al. Magnetic resonance evidence of perineural metastasis. J Neuroimaging 1995; 2: 122- 5. 3. Giles GG, Marks R, Foley P. Incidence of non- melanocytic skin cancer treated in Australia. BMJ 1988; 296: 13- 7. 4. McNab AA, Francis IC, Benger R, et al. Perineural spread of cutaneous squamous cell carcinoma via the orbit. Ophthalmology 1997; 104: 1457- 62. 5. Haydon RC III. Cutaneous squamous carcinoma and related le­sions. Otolaryngol Clin North Am 1993; 26: 57- 71. 6. Basseti C, De Tribolet N, Deruaz J, et al. Arteriovenous malfor­mation of the trochlear nerve: a rare cause of acquired isolated fourth nerve palsy. J Neuroophthalmol 1994; 14: 135- 9. 7. Rush JA, Younge BR. Paralysis of cranial nerves III, IV and VI: cause and prognosis in 1,000 cases. Arch Ophthalmol 1981 ; 99: 76- 9. 8. Salmon D, Edan G, Urvoy M. Paralysie fluctuante du IV signe longtemps isole d'un germinome. Bull Soc Ophtalmol 1982; 82: 941- 2. 9. Krohel GB, Mansour AM, Petersen WL, et al. Isolated trochlear nerve palsy secondary to a juvenile pilocytic astrocytoma. J Clin Neuroophthalmol 1982; 2: 119- 23. 10. Tychsen L, Tse DT, Ossoinig K, et al. Trochleitis with superior oblique myositis. Ophthalmology 1984; 9: 1075- 9. 11. Capone A, Jr, Slamovits TL. Discrete metastasis of solid tumours to extraocular muscles. Arch Opthalmol 1990; 108: 237- 43. 12. Divine RD, Anderson RL. Metastatic small cell carcinoma mas­querading as orbital myositis. Ophthalmic Surg 1982; 13: 483- 7. J Neuro- Ophthalmol, Vol. 20, No. 4, 2000