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Show Journal of Clinical Neuro-ophthalmology 13(4): 271-274, 1993. © 1993 Raven Press, Ltd., New York Duane's Syndrome with Giant Aneurysm of the Vertebral Basilar Arterial Junction Peter Hedera, M.D. and Robert P. Friedland, M.D. A36-year-old man who had signs of Duane's syndrome since birth developed symptoms of a posterior fossa mass. Angiography revealed a giant aneurysm in the area of the vertebral basilar junction. The association of these two anomalies provides support for the vascular origin of some cases of Duane's syndrome due to vascular hypofunction during the 4th and 5th weeks of embryogenesis. Key Words: Duane's syndrome-Giant aneurysmCongenital anomaly-Cerebral angiography-Cerebrovascular damp. From the Alzheimer Center, Department of Neurology, Case Western Reserve University, University Hospitals of Cleveland, Cleveland, Ohio, U.s.A. Address correspondence and reprint requests to Dr. Robert P. Friedland, University Hospitals of Cleveland, 2074 Abington Road, Cleveland, OH 44106, U.S.A. This work was supported in part by the National Institutes of Health, Bethesda, Maryland (AG 08012-05) and Philip Morris, U.S.A. 271 Duane's syndrome is characterized by marked limitation or absence of abduction with narrowing of the palpebral fissure on adduction secondary to retraction of the eye (1,2). Typically, Duane's syndrome can be divided into three different subtypes based on the variable limitation of adduction and exotropia of the affected eye (3). Various congenital anomalies including malformations of neural structures are associated with Duane's syndrome, suggesting that the syndrome may be caused by an in utero disturbance occurring during the period of formation of the abducens nucleus and nerve (1,2, 4). The frequency of associated congenital anomalies in Duane's syndrome has been estimated at 30-50% (4). The concurrence of Duane's syndrome with other cerebral anomalies provides important clues for better understanding of the origin and development of these anomalies. We report a case of Duane's syndrome with giant aneurysm of the vertebral basilar system and discuss the implication of the concurrence of these two anomalies. CASE REPORT A 36-year-old man had, since infancy, a history of inability to move the left eye to the left associated with occasional double vision on left lateral gaze and horizontal displacement of images. Nystagmus was not noted. He was diagnosed with Duane's syndrome at 6 years of age, and no other anomalies were present. At the age of 35 he reported problems with walking, episodic vertigo, dull occipital headache, difficulties keeping his eyes on the line while reading, and episodes of darkening of the entire visual field of a few seconds duration, frequently followed by nausea and vomiting. Shortly before examination he developed difficulties with swallowing and slurred speech. Neurologic examination at the time of admission 272 P. HEDERA AND R. P. FRIEDLAND to the Mount Sinai Hospital, New York City, demonstrated normal mental status. He had bilateral papilledema with hemorrhages and visual acuity was 20/25 00 and 20/30 as with correction. Visual field examination revealed bilaterally enlarged blind spots on target screen test. Pupils were equal with preserved light and accommodation reactions. Abduction of the left eye was diminished with narrowing of the left palpebral fissure on right lateral gaze. Vertical gaze was unlimited with upbeat nystagmus. Volitional and reflex palatal movements were limited, more on the left side, and indirect laryngoscopy revealed paralysis of the left vocal cord. Wasting of the right side of the tongue was present with fasciculations bilaterally on electromyographic examination. Muscle tone and strength were intact. Reflexes were brisk and symmetrical, and no pathologic reflexes were present. Coordination was without hypermetria, but intention tremor and dysdiadochokinesia were observed bilaterally, slightly worse on the left side. Sensory examination was intact. Gait was widebased and slow with a large turning circle and with a tendency to fall to the left. X-ray computed tomography showed enhancement in the posterior fossa in the midline after the application of contrast, and mild triventricular hydrocephalus. Vertebral angiography revealed a 5-cm diameter aneurysm in the area of the vertebral basilar junction (Figs. 1 and 2). Left vertebral injection filled the aneurysm with only slight filling of the basilar artery. Angiography of the right vertebral artery showed filling of the basilar artery before visualization of the aneurysm with minimal signs of retrograde flow to the left vertebral artery. The basilar artery originated on the apex of the aneurysmal sac and both anterior inferior cerebellar arteries were fed directly from the anomaly. A permanent clip was placed on the left vertebral artery above the origin of the left posterior inferior cerebellar artery near its entrance to the aneurysm. Angiography after the operation demonstrated occlusion of the left vertebral artery, with filling of the aneurysm persisting from the right vertebral artery without change in aneurysm size. Reoperation was done to find the neck of the aneurysm, but origination of the basilar artery from the sac made any attempt to close the aneurysm impossible. Subsequent angiography demonstrated a patent right vertebral artery and massive thrombosis of the aneurysm. Locked-in syndrome with progression to bulbar failure developed and suggested infarction of the brainstem due to thrombosis of the basilar artery. The patient expired on the same day. Autopsy consent was refused. JClin Neuro-ophthalmol, Vol. 13, No.4, 1993 FIG. 1. Lateral projection with catheterization of the right vertebral artery shows the aneurysm with filing of the basilar artery. (Preoperative angiography.) DISCUSSION Our patient had documented Duane's syndrome since early infancy, corresponding to the first subtype according to Huber's classification (3), without evidence of other anomalies. It is also possible that Duane's syndrome and giant aneurysm were present together in this case by chance. However, the development of the vertebral basilar arterial system and brainstem is closely integrated and patients with Duane's syndrome have a 10 to 20 times higher risk than the general population for associated anomalies (2,4). This provides considerable foundation to support the view that these anomalies may be related. The most common abnormalities in Duane's syndrome are skeletal alterations with craniofacial malformations or Klippel-Feil anomaly, often associated with deafness, and cardiac or ocular malformations (4). Duane's syndrome with associated malformations is likely a hetergeneous group with multiple causes. A common teratogenic insult during an early developmental period has been postulated, because all involved structures are developing during the 4th to 10th week of gestation (4). DUANE'S SYNDROME WITH GIANT ANEURYSM 273 FIG. 2. Anteroposterior projection after catheterization of the left vertebral artery. Filling of the aneurysm is prominent with only slight filling of the basilar artery vascular bed. (Preoperative angiography.) Miller analyzed a group of patients with thalidomide embryopathy and found that Duane's syndrome occurred with systemic malformations suggesting a developmental disturbance in the beginning of the early part of the 4th week extending over the next 4 to 5 days (5). The formation of both the vertebral basilar vascular system and the abducens nerve is linked in close chronologie and morphologic proximity during embryogenesis (6,7). The basilar artery originates from the fusion of longitudinal channels running along the ventral surface of the hindbrain, formed and fed from a plexus of presegmental branches of the dorsal aorta; on the caudal pole they give origin to the vertebral arteries. Differentiation of the vertebral basilar system takes place at about 32-35 days after' conception, when basal structures of all arteries are developed (6). The development of the abducens nucleus and nerve are closely related to the formation of the pontine flexure at about the end of the 4th week with the discrimination of six transverse rhombic groves; the fourth rhombic grove is linked to the sixth cranial nerve and its nucleus, which appears at about the 30th day after conception (7). Theories concerning the origin and development of cerebral aneurysms have long been disputed and evidence suggesting a role of congenital fac-tors has not been firmly established (8). The most frequent localization of aneurysms is at the apex of arterial bifurcations, which favors the importance of hemodynamic factors acting on the distal carina of a bifurcation (8). The presence of saccular aneurysms in the vertebrobasilar junction violates this rule and this atypical location has been linked to severe atherosclerotic changes (8), which were not present in our case. Aneurysms of the vertebral basilar arterial junction are also often associated with basilar artery fenestration, where they are almost exclusively located at the proximal end of the fenestration (9). Fenestration of the basilar artery is a result of incomplete fusion of the embryonal arteries. The distal carina allows hemodynamic factors to affect the development of aneurysms. The aneurysm in our patient, originating at the vertebral basilar junction which lacks a distal carina, implies a different mechanism due to a congenital abnormality. A teratogenic insult (suggested as a cause of Duane's syndrome) (4) could have inhibited organization of primitive arteries forming the basilar artery. However, hemodynamic factors also contributed to the growth of the aneurysm, which in its late stages mimicked a posterior fossa tumor due to enlargement of the size of the vascular sac (10). The association of Duane's syndrome with an anomaly in the vertebral basilar circulation provides an important clue about the mechanism of the sixth nerve defect. Pathologic reports in Duane's syndrome have demonstrated the absence of motor neurons in the abducens nucleus and absence of the sixth cranial nerve (11,12). It is likely that strabismus in patients with Duane's syndrome is a result of the reparative process, with branches of the third cranial nerve supplying the otherwise uninnervated lateral rectus muscle (5). A necessary condition for development of brain structures is a sufficient blood supply. The pontine tegmentum is supplied by short branches originating from the basilar artery. Vascular hypofunction due to anomalous formation of the basilar artery and its branches may have caused an underdevelopment of the abducens nucleus during critical phases of the embryogenesis. Even though two pathologic reports analyzing cases with Duane's syndrome have not found significant vascular anomalies (11,12), this is still consistent with the proposed heterogeneous etiology of Duane's syndrome (2,4). Cases with Mobius syndrome (bilateral facial paralysis with unilateral or bilateral abducens palsy) have increased frequency of associated vascular anomalies (13). Indeed, Bavick and Weaver (14) have proposed a vascular etiology for J Clin Neuro-ophthalmol, Vol. 13, No.4, 1993 274 P. HEDERA AND R. P. FRIEDLAND Mobius syndrome, Klippel-Feil and Poland anomalies (anomaly of pectoral muscles and upper limb). Klippel-Feil deformity together with other skeletal malformations are also frequently present in patients with Duane's syndrome (3). So, it is plausible that vascular mechanism plays a role in certain cases of Duane's syndrome. The close relationship of the vertebral and basilar arteries and the abducens nucleus in the pons favors a vascular mechanism as one of the causes of Duane's syndrome. Anomaly of the vertebral basilar arterial junction could lead to vascular hypofunction and focal hypoperfusion of the pons with the most critical phase between the 4th and 5th week of the embryogenesis. Acknowledgments: The patient was under the care of Morris B. Bender while at the Mount Sinai Hospital in New York and under the care of Charles G. Drake while in the Hospital of the University of Western Ontario, London, Canada. REFERENCES 1. Smith AG. Duane's syndrome. Ophthal Semin 1977;2:33-72. 2. Kowal VO, McKeown CA. Duane's syndrome. Int Ophthalmol Clin 1992;32:51--62. / Clin Neuro-ophthalmol, Vol. 13, No.4, 1993 3. Huber A. Electrophysiology of the retraction syndromes. Br J OphthalmoI1974;58:293-300. 4. Pfafenbach DO, Cross HE, Kearns TP. Congenital anomalies in Duane's retraction syndrome. Arch OphthalmoI1972; 88:635-9. 5. Miller MT. Thalidomide embryopathy: a model for the study of congenital incomitant horizontal strabismus. Trans Am Ophthalmol Soc 1991;89:623-74. 6. Nordem OM. Development of craniofacial blood vessels. In: Feinberg RN, Sherer GK, Auerback R, eds. The development of the vascular system. Basel: Karger; 1991:1-24. 7. Muller F, O'Rahilly R. The development of the human brain from a closed neural tube at stage 13. Anat Embryol 1988;177:203-24. 8. Sekhar LN, Heros RC. Origin, growth, and rupture of saccular aneurysms: a review. Neurosurgery 1981;8:248--60. 9. Campos J, Fox AJ, Vinuela F, et al. Saccular aneurysms in basilar artery fenestration. AJNR 1987;8:233--6. 10. Michael WF. Posterior fossa aneurysms simulating tumours. J Neurol Neurosurg Psychiatry 1974;37:218-23. 11. Hotchkiss MG, Miller NR, Clark AW, Green WR. Bilateral Duane's syndrome: a clinical-pathologic report. Arch OphthalmoI1980; 98:870-4. 12. Miller NR, Kiel SM, Green WR, Clark AW. Unilateral Duane's retraction syndrome (type 1). Arch Ophthalmol 1982; 100:1468-72. 13. Raroque HG Jr, Hershewe GL, Snyder RD. Mobius syndrome and transposition of the great vessels. Neurology 1988;38:1894-5. 14. Bavinck JN, Weaver DO. Subclavian artery supply disruption sequence: hypothesis of a vascular etiology for Poland, Klippel-Feil, and Mobius anomalies. Am J Med Genet 1986; 23:903-18. |
