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Show Journal of Neuro- Ophthalmology 14( 1): 24- 28, 1994. © 1994 Raven Press, Ltd., New York Therapy- Resistant Papilledema in Achondroplasia Klara Landau, M. D., and Balder P. Gloor, M. D. A 20- year- old achondroplastic dwarf developed severe papilledema over a short period of time. Since the age of 3 he had a ventriculoperitoneal shunt for presumed hydrocephalus. Severe ventriculomegaly was never documented, neither in the past, nor at presentation. Intracranial pressure was high, and the shunt was obliterated. Despite prompt shunt revision and subsequent bilateral optic nerve sheath decompression the patient developed postpapilledema optic atrophy with bilateral blindness. The pathophysiology of increased intracranial pressure in achondroplasia is discussed. Key Words: Achondroplasia- Papilledema- Hydrocephalus- Pseudotumor cerebri. From the Department of Ophthamology, University Hospital Zurich, Switzerland. Address correspondence and reprint requests to Dr. Klara Landau, Department of Ophthamology, University Hospital Zurich, Frauenklinikstrasse 24, 8091 Zurich, Switzerland. Achondroplasia is known to be associated with neurological signs and symptoms resulting from brainstem compression, spinal cord compression, and hydrocephalus. We report a unique case of severe papilledema which, despite treatment, resulted in total optic atrophy in a patient with classical findings of achondroplasia. The pathogenetic mechanism of papilledema in this disorder is discussed with special attention to the role of intracranial venous hypertension. CASE REPORT The patient's history goes back to the age of 3 when the diagnosis of achondroplasia, macroceph-aly, and right retroauricular venous malformation was made. He was referred to the Neurosurgery Department for treatment of the vascular malformation. Angiographically no connection between the varix and the intracranial vascular system was found. The boy showed clinical signs of increased intracranial pressure ( ICP) and his head circumference was markedly over the 97th percentile. Under the presumed diagnosis of hydrocephalus a ventriculoperitoneal shunt was placed. Intraopera-tively the intracranial pressure was not found to be markedly elevated. Two months later the varix was removed and the right cerebellum explored. Fine pathological vessels and " red veins" were found on the right cerebellar surface and tentorium. Until the age of 9 t he boy repeatedly suffered intermittent episodes of increased ICP. Several shunt revisions were performed. A first computed tomography scan ( CT) at the age of 7 showed a normal- sized ventricular system. In February 1991, at the age of 20, a routine eye examination was performed. Visual acuity was 20/ 20 OU and the discs were recorded as normal. On May 30, 1991 the patient presented to the University Eye Department Zurich with com- 24 PAPILLEDEMA IN ACHONDROPLASIA 25 plaints of mild visual loss in his left eye and intermittent obscurations of vision. Visual acuity was 20/ 30 in the right eye and 20/ 50 in the left eye, there was a mild relative afferent pupillary defect on the left, both discs were severely swollen and visual fields showed enlarged blind spots bilaterally and an inferior nasal defect on the left. The right ab-ducens nerve was paretic. The patient was admitted to the Neurosurgery Department. Neuroradio-logic evaluation revealed no hydrocephalus. A cerebrospinal fluid ( CSF) circulation study showed elevated ICP with distal obstruction of the shunt. On June 5, 1991 a new shunt was placed. The patient's visual function was reevaluated 1 week following the shunt replacement. There was no significant change in visual acuity, visual fields, and disc appearance. By June 28, 1991 visual acuity dropped to 20/ 40 OD and counting fingers OS with deterioration of the visual fields and increased disc swelling with retinal hemorrhages ( Fig. 1). Under these circumstances an indication for optic nerve sheath decompression was given despite the functioning ventriculoperitoneal shunt. On July 2 and 5,1991 surgery was performed on the left and right optic nerve, respectively, via the medial approach as described by Sergott et al ( 1). In each instance, clear CSF under pressure escaped from the slits in the optic nerve sheaths. There was no hemorrhage or other complications during the surgeries. Two days following the optic nerve sheath decompression on the left side visual acuity improved to 20/ 100 and the visual field expanded slightly. In the right eye visual acuity and visual field continued to deteriorate; the preoperative acuity of 20/ 70 never improved. Several days following the second surgery both discs became increasingly pale with severe vessel constriction and the visual function collapsed. Megadose steroid therapy was initiated and a magnetic resonance image ( MRI) repeated; this showed bilateral leakage of CSF into the retrobulbar space ( Fig. 2). Over the following weeks the patient lost light perception in both eyes and a total optic atrophy developed ( Fig. 3). DISCUSSION Achondroplasia is an autosomal dominant disorder of endochondral ossification, which results in disproportionately short stature. The limbs are short, the trunk is of normal length, the head is large with a bulging forehead and a depressed nasal bridge. The genetic locus responsible for the disease has not yet been identified. Over 80% of cases represent new mutations ( 2). Achondroplasia is compatible with a normal lifespan and intelligence, but neurologic morbidity has long been appreciated. Narrowing of the foramen magnum and of the spinal canal ( Fig. 4) may result in compression of the medulla oblongata and the spinal cord with sudden apneas and tetraparesis ( 3). Ven-triculomegaly can occur in achondroplasia and its cause has been studied recently by Steinbok and coworkers ( 4) in five achondroplastic children. Evidence was found that the enlarged ventricles represent active hydrocephalus with increased intracranial pressure and impaired reabsorption of CSF into the sagittal sinus. This was shown to be the result of raised intracranial venous pressure due to FIG. 1. Fundus photograph of the right eye ( A) and the left eye ( B) taken 3 weeks after replacement of the ventriculoperitoneal shunt, showing severe bilateral papilledema with intraretinal hemorrhages throughout the posterior pole. / Nairo- Ophthalmot, Vol. 14, No. 1, 1994 26 K. LANDAU AND B. P. GLOOR fB] FIG. 2. T2- weighted axial MR scan through the right ( A) and left ( B) orbit taken 10 and 13 days after optic nerve sheath fenestration on the left and right side, respectively, showing leakage of cerebrospinal fluid into the retrobulbar space. hemodynamically significant bilateral stenosis of the jugular foramen. Welter ( 5) was the first to propose this mechanism of venous obstruction at the level of the skull base causing hydrocephalus in achondroplasia. The ultimate proof of this pathogenetic mechanism was provided by Lundar and coworkers ( 6) who successfully treated a 10- month- old achondroplastic child with hydrocephalus by venous decompression at the jugular foramen. In our patient the first ventriculoperitoneal shunt was placed before modern imaging methods were available. We thus do not know whether ven-triculomegaly was present before the first surgery. Subsequent studies never showed a massive enlargement of the ventricles. He had repeated episodes of shunt malfunction with headache and vomiting throughout his childhood. Some passed without treatment, twice the shunt had to be replaced. It is likely that during these episodes papilledema developed, even though it was not recorded. fBI FIG. 3. Fundus photograph of the right eye ( A) and the left eye ( B) taken 4 months after presentation, showing total postpapilledema optic atrophy. ] Neuro- Ophthalmol, Vol. 14, No. 1, 1994 PAPILLEDEMA IN ACHONDROPLASIA 27 FIG. 4. T2- weighted midsagittal MR scan of the cra-niocervical junction of our patient showing features typical for achondroplasia: a narrow foramen magnum and spinal canal as well as a steep clivus. What was the mechanism of papilledema with rapid and complete deterioration of vision in our patient? Undoubtedly, his intracranial pressure was increased at presentation and several times before, be it due to hydrocephalus as discussed above or as part of a pseudotumor syndrome. In pseudotumor cerebri, cranial venous outflow impairment constitutes one of the rare identifiable causes of the disease. The mechanism by which intracranial pressure rises is supposed to be impaired absorption of CSF due to reversal of the normal positive CSF to superior sagittal sinus pressure gradient ( 7). In pseudotumor cerebri with long- standing papilledema visual morbidity is very common ( 8,9) and can be severe. Rare cases of " malignant" papilledema have been reported ( 10). Another mechanism could contribute to the development of papilledema in achondroplasia. One of the possible causes of rare occurrences of papilledema reported in patients with spinal cord tumors is the failure of the narrowed spinal canal to act as an elastic reservoir for balancing CSF pressure fluctuations ( 11). Our patient had an extremely narrowed spinal canal; a typical finding in achondroplasia ( Fig. 4). The ventriculoperitoneal shunt replacement performed in our patient did not reduce the increased CSF pressure around the retrobulbar optic nerves. This has been previously reported ( 12) and the postulated mechanism is a three- compartment system consisting of the subarachnoid space around each optic nerve and the subarachnoid space around the brain ( 13) with highly variable communication between these compartments ( 14). In such cases, an optic nerve decompression has been advocated and successfully performed in a number of cases ( 12). In our patient this procedure failed to improve visual function. We do not believe that our surgical technique was inadequate, as care was taken to dissect possible trabeculations around the nerve on each side. Moreover, the postoperative MRI performed 2 weeks after the procedure showed a large fistula of CSF next to the retrobulbar optic nerve on each side ( Fig. 2) similar to a case reported by Hamed and colleagues ( 15). Possibly, the optic nerve sheath decompression was performed at a late time in the course of the disease when damage to the axons had been too severe for recovery. This has been observed by others ( Corbett JJ, personal communication, 1992). Some time was lost while waiting for improvement following replacement of the shunt. In view of the above- mentioned important role of venous hypertension both in hydrocephalus associated with achondroplasia and in pseudotumor cerebri, optic nerve sheath decompression might have been more successful if performed as an initial procedure. If we bear in mind that patients may tolerate papilledema for months to years without losing vision, this therapy- resistant case remains puzzling. Possibly a subclinical damage to the optic nerve axons from previous attacks of increased intracranial pressure in our patient led to this stunning course of events. We would like to draw the reader's attention to the possibility of severe threat to vision in achondroplastic patients with increased intracranial pressure. Acknowledgments: The authors wish to thank Dr. A. Superti- Furga for providing several references on achondroplasia and Dr. E. Korach for reviewing the manuscript. REFERENCES 1. Sergott RC, Savino PJ, Bosley TM. Modified optic nerve sheath decompression provides long- term visual improvement for pseudotumor cerebri. Arch Ophthalmol 1988; 106: 1384- 90. 2. Horton WA, Hecht JT. The Chondrodysplasias. In: Royce PM, Steinmann B, eds. Connective tissue and its heritable disorders: molecular, genetic, and medical aspects. New York: Wiley- Liss; 1993: 644- 6. 3. Hecht JT, Butler IJ. Neurologic morbidity associated with achondroplasia / Child Neurol 1990; 5: 84- 97. / Neuro- Ophthalmol, Vol. 14, No. 1, 1994 28 K. LANDAU AND B. P. GLOOR 4. Steinbok P, Hall J, Flodmark O. Hydrocephalus in achondroplasia: the possible role of intracranial venous hypertension. / Neurosurg 1989; 71: 41- 8. 5. Welter H. Zur Frage des Hydrocephalus chondrodystrophi-cus congenitus. Beitr Pathol Anat 1936; 97: 1- 8. 6. Lundar T, Bakke SI, Nornes H. Hydrocephalus in an achondroplastic child treated by venous decompression at the jugular foramen. / Neurosurg 1990; 73: 138- 40. 7. Johnston I, Hawke S, Halmagyi M, Teo C. The pseudotumor syndrome: disorders of cerebrospinal fluid circulation causing intracranial hypertension without ventriculome-galy. Arch Neurol 1991; 48: 740- 7. 8. Rush JA. Pseudotumor cerebri: clinical profile and visual outcome in 63 patients. Mayo Clin Proc 1980; 55: 541- 6. 9. Corbett JJ, Savino PJ, Thompson HS, et al. Visual loss in pseudotumor cerebri: follow- up of 57 patients from five to 41 years and a profile of 14 patients with permanent severe visual loss. Arch Neurol 1982; 39: 461- 74. 10. Kidron D, Pomeranz S. Malignant pseudotumor cerbri: report of two cases. / Neurosurg 1989; 71: 443- 5. 11. Ammermann BJ, Smith DR. Papilledema and spinal cord tumors. Surg Neurol 1975; 3: 55- 7. 12. Kelman SE, Sergott RC, Cioffi GA, et al. Modified optic nerve decompression in patients with functioning lumbo-peritoneal shunts and progressive visual loss. Ophthalmology 1991; 98: 1449- 53. 13. Keltner JL, Albert DM, Lubow M, al. Optic nerve decompression: a clinical pathologic study. Arch Ophthalmol 1977; 95: 97- 104. 14. Hayreh SS. Pathogenesis of oedema of the optic disc. Doc Ophthalmol 1968; 24: 289^ 11. 15. Hamed LM, Tse DT, Glaser JS, Byrne SF, Schatz NJ. Neu-roimaging of the optic nerve after fenestration for management of pseudotumor cerebri. Arch Ophthalmol 1992; 110: 636- 9. I Neuw- Ophthalmol, Vol. 14, No. 1, 1994 |
