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Show Journal of Neiiro- Opluhalmology 17( 1): 36- 38, 1997. © 1997 Lippincott- Raven Publishers, Philadelphia Brief Communication Bilateral Visual Loss and Simultagnosia After Lumboperitoneal Shunt for Pseudotumor Cerebri Neil R. Miller, M. D. Lumboperitoneal shunting ( LPS) for pseudotumor cerebri may be associated with a number of complications, including obstruction of the shunt, intracranial hypotension caused by excessive drainage of cerebrospinal fluid via the shunt, lumbar radiculopathy, shunt infection, shunt- related abdominal pain, migration or dislocation of the peritoneal end of the catheter, subdural hematoma, syringomyelia, and tonsillar herniation ( 1- 10). We recently evaluated a patient with pseudotumor cerebri who experienced the unusual complication of bilateral visual loss associated with simultagnosia from rupture of a previously asymptomatic intracranial aneurysm after apparently uncomplicated LPS. The patient was a 42- year- old woman with well-documented pseudotumor cerebri who underwent a lumboperitoneal shunt because of worsening papilledema despite treatment with acetazolamide ( 500 mg b. i. d.). Within 24 h after the shunt was placed, the patient became confused and complained of a headache and blurred vision. Examination revealed that she had decreased visual acuity of 10/ 200 OU, decrease color vision in both eyes, and simultagnosia. Magnetic resonance imaging found evidence of bilateral occipital infarcts and herniation of the cerebellar tonsils below the level of the foramen magnum ( Fig. 1). A cerebral angiogram demonstrated diffuse cerebral vasospasm, associated with a saccular aneurysm located at the junction of the left vertebral and posterior- inferior cerebellar arteries ( Fig. 2). The patient underwent balloon angioplasty Manuscript received May 23, 1995; accepted June 9, 1995. From Wilmer Ophthalmological Institute, The Johns Hopkins Hospital, Baltimore, Maryland, U. S. A. Address correspondence to Dr. Neil R. Miller, Wilmer Ophthalmological Institute, The Johns Hopkins Hospital, Baltimore, MD, 21205. of the vertebral artery, followed by clipping of the aneurysm. At the time of surgery, there was a clot around the dome of the aneurysm and evidence of subarachnoid hemorrhage. The patient never experienced significant recovery of vision, and on subsequent computed tomographic ( CT) scanning bilateral parieto- occipital infarcts were evident ( Fig. 3). We theorize that in our patient, the sudden reduction in intracranial pressure that occurred when i- iu. i . unenhanced T1- weighted sagittal magnetic resonance image obtained after lumboperitoneal shunting shows that the cerebellar tonsils now lie below the foramen magnum ( large arrowhead). Also note the hypointense area at the tip of the right occipital pole, suggesting infarction ( small arrowhead). 36 ANEURYSM RUPTURE AFTER LP SHUNT 37 ( A, B) FIG. 2. Cerebral angiography shows a diffuse vasospasm affecting the anterior ( A, B) and posterior ( C) cerebral circulations. Note that a saccular aneurysm is present at the origin of the right posterior- inferior cerebellar artery. A: Selective right internal carotid artery injection, anteroposterior view. B: Selective left internal carotid artery injection, anteroposterior view. C: Selective right vertebral artery injection, anteroposterior view. the patient underwent LPS caused herniation of the cerebellar tonsils and that either the herniation or the reduction in pressure itself led to rupture of the previously asymptomatic aneurysm, resulting in vasospasm and bilateral parieto- occipital lobe infarctions. A somewhat similar case was reported by Gosselin and Boghen ( II). Their patient was a 64- year- old woman who experienced a sudden headache associated with loss of vision in both eyes; she was found to have transient cortical blindness. An unenhanced CT scan gave normal results, but on a lumbar puncture the patient was found to have suffered an acute subarachnoid hemorrhage. A cerebral angiogram showed evidence of diffuse vasospasm and an aneurysm at the junction of the right internal carotid and posterior communicating arter- ./ Nciiro- Opluhalmol, Vol. 17. No. 1. 1997 38 N. R. MILLER FIG. 3. Unenhanced computed tomographic axial scan obtained 6 months after lumboperitoneal shunting shows low- density areas suggestive of infarcts in both occipital and posterior parietal lobes. ies. The patient regained normal visual function - 11 days after the hemorrhage, and the aneurysm subsequently was treated without difficulty. Gosse-lin and Boghen postulated that the transient cortical blindness that occurred in their case was caused by vasospasm, and our case would seem to support that theory. We believe that the potential complications of LPS, including the rare occurrence of bilateral visual loss and simultagnosia, should be considered when deciding whether to perform a lumboperitoneal shunt in a patient with pseudotumor cerebri, particularly when that patient has no evidence of optic neuropathy. REFERENCES 1. Eisenberg HM, Davidson RI, Shillito J. Lumboperitoneal shunts: review of 34 cases. J Neurosurg 1971; 35: 427- 31. 2. Fischer EG, Welch K, Shillito J. Syringomyelia following lumboperitoneal shunting for communicating hydrocephalus: report of three cases. J Neurosurg 1977; 47: 96- 100. 3. Selman WR, Spelzler RF, Wilson CB, Grollmus JW. Percutaneous lumboperitoneal shunt: review of 130 cases. Neurosurgery 1980; 6: 255- 7. 4. Johnston I, Paterson A, Besser M. 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