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Show Journal of Neuw- Ophthalmology 19( 4): 249- 251, 1999. © 1999 Lippincoll Williams & Wilkins, Inc., Philadelphia Arachnoid Cyst of the Cavernous Sinus Resulting in Third Nerve Palsy Dai Barr, F. R. c. Ophth., Mark J. Kupersmith, M. D., A 67- year- old man exhibited long- standing left third nerve palsy. Magnetic resonance imaging revealed a cystic lesion in the left cavernous sinus with signal characteristics typical of arachnoid cyst. Intradural cavernous sinus arachnoid cyst has not reported previously. Pathogenetic mechanisms are discussed. Key Words: Arachnoid cyst- Cavernous sinus- Magnetic resonance imaging- Third nerve palsy. Arachnoid cysts occur throughout the cerebrospinal axis ( 1) and comprise approximately 1% of all intracranial space- occupying lesions ( 2). In the cranial cavity, arachnoid cysts are usually solitary, associated with normal subarachnoid cisterns, found in the middle cranial fossa, and asymptomatic ( 1). A case of an arachnoid cyst of the cavernous sinus that resulted in a third nerve palsy is presented. CASE REPORT A 67- year- old man with a 20- year history of diplopia in the primary position was examined. He was aware that his left pupil had been larger than the right for approximately 20 years. He had no other neurologic symptoms; no history of head trauma, diabetes mellitus, or systemic hypertension, and was on no medication. Examination revealed corrected visual acuities of 20/ 20 in both eyes, normal color vision, and full fields. There was no ptosis or proptosis. The right and left pupil diameters were 4 mm and 7 mm, respectively, and reacted briskly to light. There was 2+ underaction of the left inferior oblique, superior rectus, and inferior rectus and 1+ underaction of the medial rectus. Prism cover test in the primary position revealed a right hypertropia ( RHT) of 12 prism diopters ( PD) and an exotropia ( XT) of 10 PD. In right gaze, there was an RHT of 16 PD and an XT of 14 PD, and in left gaze there was an RHT of 12 PD and an XT of 5 PD. In upgaze, there was an RHT of > 16 PD and an XT of 10 PD, and in downgaze there was Manuscript received January 5, 1999; accepted June 30, 1999. From the Departments of Neuro- Ophthalmology ( D. B., M. K., R. T.) and Radiology ( R. P.), Beth Israel Institute for Neurology and Neurosurgery, New York, New York, U. S. A. Address correspondence and reprint requests to Mark J. Kupersmith, M. D., INN, Beth Israel North, 170 East End Ave., New York, NY 10128; E- mail: mkuper@ bethisraelny. org ., Richard Pinto, M. D., and Roger Turbin, M. D. an RHT of 8 PD and an XT of 12 PD. There were no synkinetic movements of the upper lid, globe, or pupil. The remainder of the findings of ophthalmologic and neurologic examination were normal. A diagnosis of long- standing incomplete pupil-involving left third nerve palsy was made, and because of a lack of etiology, magnetic resonance imaging ( MR1) of the brain was performed. The MRI included axial Tl-and T2- weighted images, axial fluid attenuated inversion recovery images, an axial diffusion study, and a three-dimensional time of flight MRI angiogram of the circle of Willis. A multiloculated cystic mass, which displaced the cavernous internal carotid artery anteromedially was evident within the left cavernous sinus ( Figs. 1- 3). The left posterior clinoid process was truncated. The pituitary gland and visual pathways were normal. The signals from the mass were identical with that of cerebrospinal fluid ( CSF) on all sequences. The remainder of the brain MRI study was normal. Based on the MRI findings, a diagnosis of left cavernous arachnoid cyst was made. In view of the chronic-ity and stability of the patient's symptoms, no neurosurgical treatment was contemplated. DISCUSSION A mass with a cystic appearance within the cavernous sinus, viewed with computed tomography or MRI, may be pituitary adenoma, craniopharyngioma, Rathke's cleft cyst ( 3), dermoid cyst ( 4), or hydatid cyst ( 5). These lesions were excluded as possible diagnoses in our patient because none of these lesions has an MRI appearance in which the cyst contents are isointense with CSF, as occurs with an arachnoid cyst. Normal diffusion-weighted imaging study suggested the mass was not an epidermoid cyst: unlike an arachnoid cyst, water within an epidermoid cyst is restricted and produces an abnormally high signal. Arachnoid cysts may develop at any age and may be congenital, as a result of early developmental splitting of the arachnoid membrane ( 1), or may be acquired through infection, inflammation, or trauma ( 6). Communication of the arachnoid cyst with the subarachnoid space often persists, and progressive enlargement may occur because of a ball- valve mechanism ( 6). Arachnoid cysts are intra-arachnoidal ( 1,6,7), with the wall closely resembling the lining of arachnoid granulations ( 1). The contents of an 249 250 D. BARRETAL. n 6* 0B: 20: 27 & Hw; - 2, lb, 5 J * A J FIG. 1. Axial T1- weighted magnetic resonance image of the brain. A low signal cystic mass is seen in the left cavernous sinus, which is displacing the intracavernous internal carotid artery anteriorly. The posterior clinoid process is truncated. • : 7 » x 123,9 5E R; 4200 E: 105/£ F C: l/ 1 15, GkHz EftD 5.0t> k/ 2.0sp FIG. 2. Axiai i ii- weigntea magnetic resonance image ot tne brain, me intracavernous cyst contents are isolntense with cerebrospinal fluid. ./ Neuro- Ophtlmlmol, Vol. 19, No. 4, 1999 THIRD NERVE PARESIS IN CAVERNOUS SINUS 251 n £& Apr y. 06: 24: 3; Mai \ l£ kHz 0 K22 FIG. 3. Axial fluid attenuated inversion recovery magnetic resonance image of the brain. The signal from the intracavernous cyst contents has been attenuated to the same degree as the cerebrospinal fluid. arachnoid cyst may be indistinguishable from CSF or, rarely, may contain blood ( 2). Arachnoid cysts usually occur in relation to the brain surface, but they may be intraventricular, intrasellar, or orbital, and approximately 10% occur in the sellar or suprasellar areas ( 1). We have found no prior descriptions of an arachnoid cyst occuring in the cavernous sinus. When present, symptoms depend on the location and size of the arachnoid cyst and may be the result of a local mass effect on adjacent structures, obstructive hydrocephalus, or the consequences of a space- occupying lesion. Third nerve palsy has been reported with an arachnoid cyst of the interpeduncular cistern ( 7,8) and with a hemorrhage into a suprasellar arachnoid cyst ( 9). In the lateral wall of the cavernous sinus, the third and fourth nerves and the ophthalmic and maxillary divisions of the trigeminal nerve are all enclosed by separate arachnoidal epithelial membranes whose elements penetrate the nerve sheaths and inner dura to form arachnoid granulations within the cavernous venous sinus ( 10). The same is also true of the arachnoid membrane around the trigeminal ganglion in Meckel's cave ( 10). It is therefore possible that, in utero, a splitting of the arachnoid membrane in one of these locations allowed an arachnoid cyst to form. A slow increase in the mass was likely because the third nerve palsy did not manifest until the patient was in middle age. To our knowledge, the occurrence of a symptomatic arachnoid cyst within the cavernous sinus has not been reported previously. Although rare, an arachnoid cyst should be considered in the differential diagnosis of a cystic lesion in the cavernous sinus found with an MRI. REFERENCES 1. Rengachary SS, Watanabe I. infrastructure and pathogenesis of intracranial arachnoid cysts. J Neiiropathol Exp Neurol 1981 ; 40: 61- 83. 2. Leo JS, Pinto RS, Hulvat GF, Epstein F, Kricheff II. Computed tomography of arachnoid cysts. Radiology 1979; 130: 675- 80. 3. El- Mahdy W, Powell M. Transsphenoidal management of 28 symptomatic Rathke's cleft cysts, with special reference to visual and hormonal recovery. Neurosurgery 1998; 42: 7- 17. 4. North KN, Antony JH, Johnston IH. Dermoid of cavernous sinus resulting in isolated oculomotor nerve palsy. Pediatr Neurol 1993; 9: 221- 3. 5. Kanpolat Y, Mertol T, Sekerci Z, Kokes F. Hydatid cyst of the cavernous sinus. Clin Neurol Neurosurg 1988; 90: 175- 6. 6. Krawchenko J, Collins GH. Pathology of an arachnoid cyst: Case report. J Neurosurg 1979; 50: 224- 8. 7. Lindenberg R, Walsh FB, Sacks JG. Neuropathology of vision: an atlas Philadelphia: Lea and Febiger. 1973: 300- 1. 8. Lesser RL, Geehr RB, Higgins DD, et al. Ocular motor paralysis and arachnoid cyst. Arch Ophthalmol 1980; 98: 1993- 5. 9. Ide C, De Coene B, Gilliard C, Polio C, Hoebeke M, Godfraind C, Trigaux JP. Hemorrhagic arachnoid cyst with third nerve paresis. AJNR 1997; 18: 1407- 10. 10. Krivosic I. Histoarchitecture of the cavernous sinus. In: Dolenc VV, ed. The Cavernous Sinus: A multidisciplinary approach to vascular and tumorous lesions. New York: Springer- Verlag, 1987: 117- 29. J Neuro- Ophllwlmol, Vol. 19. No. 4, 1999 |
