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Show PHOTO ESSAY Chiasmal High Signal on Magnetic Resonance Imaging in the Atrophic Phase of Leber Hereditary Optic Neuropathy Figen Batioglu, MD, Huban Atilla, MD, and Teksin Eryilmaz, MD mm An m\ Ml • ~^ m ~* Til FIG. 1. Coronal T2 magnetic resonance imaging performed 3 months after acute visual loss in the first- affected ( right) eye shows hyperintense signal in the right half of the optic chiasm ( black arrow). FIG. 2. Coronal T2 magnetic resonance imaging performed 6 months after acute visual loss in the second-affected ( left) eye shows hyperintensive signal on both sides of the optic chiasm ( arrows). Abstract: A 30- year- old man with Leber hereditary optic neuropathy mutation 11778 displayed no magnetic resonance imaging abnormalities during the acute phase of visual loss in the right eye. Three months later, during the acute phase of visual loss in the left eye, magnetic resonance imaging showed T2 hyperintense signal changes on the right half of the optic chiasm. Six months later, magnetic resonance imaging revealed T2 hyperintense signal changes on both sides of the optic chiasm. This is the first reported case of optic chiasmal involvement on magnetic resonance imaging in the atrophic phase of Leber hereditary optic neuropathy. ( JNeuro- Ophthalmol 2003; 23: 28- 30) Ankara University, School of Medicine, Department of Ophthalmology, Neuro- Ophfhalmology Department, Ankara, Turkey. Address correspondence to Figen Batioglu, MD, Giizaltan Sokak 22/ 6, 06570 Ankara, Turkey; E- mail: batioglu@ hotmail. com A30- year- old man developed severe and sudden visual loss OD in May 2000. Visual acuity was counting fingers at 1 meter OD and 20/ 20 OS. There was an afferent pupillary defect OD. Fundoscopic examination revealed mild optic disc hyperemia with indistinct margins. Magnetic resonance imaging ( MRI) was unremarkable. Optic neuritis was suspected and corticosteroid pulse therapy was given. There was no recovery of visual acuity. Three months later ( August 2000), the same symptoms appeared OS. Ophthalmologic examination revealed a visual acuity of counting fingers at 1 meter OD and 2 meters OS. Pupil reactions were sluggish without an afferent pupillary defect. Fundus examination revealed temporal optic disc pallor on the OD and hyperemic papilla with indistinct margins OS. MRI now revealed hyperintense signal change on the right half of the optic chiasm ( Fig. 1). There were no size or signal abnormalities in the optic nerves on orbital MRI scans, and there were no abnormalities seen elsewhere in Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 28 J Neuro- Ophthalmol, Vol. 23, No. 1, 2003 PHOTO ESSAY JNeuro- Ophthalmol, Vol. 23, No. 1, 2003 FIG. 3. Fundus photograph taken 6 months after acute visual loss in the second- affected eye shows bilateral optic disc pallor. the brain. Optic neuritis was suspected again. Orbital ultrasonography and fundus fluorescein angiography were unremarkable. The patient was then referred to our clinic. Neuro- ophthalmologic examination 6 months after acute involvement of the OS ( February 2001) revealed a visual acuity of counting fingers in both eyes. Color vision was 0/ 14 OU using the Ishihara pseudo- isochromatic plates. Pupil size and reactions were normal without afferent pupillary defect. Motility and slit- lamp examination results were normal. MRI examination now revealed hyper-intense signals on both sides of the optic chiasm ( Fig. 2). Orbital images showed normal intraorbital structures with no signal abnormalities in optic nerves. There were no brain abnormalities on the cranial MRI. Funduscopic examination showed bilateral temporal pallor of the optic discs ( Fig. 3). Visual field examination showed bilateral inferior altitudinal defects ( Fig. 4). No systemic abnormality was found except for a hy-perechogenic nodular lesion on the right lobe of the thyroid gland. Results of laboratory studies, including complete blood cell count, serum electrolytes, serum protein electrophoresis, erythrocyte sedimentation rate, and thyroid hormones, were within normal range. Serological testing, including ANA, anti- ds- DNA, autoantibodies, and circulating immunocomplexes, was negative. Cerebrospinal fluid ( CSF) examination was normal and without oligo-clonal bands. The clinical and MRI examinations suggested chiasmal optic neuritis, and the patient was treated with systemic corticosteroids again. But there was no improvement in vision in either eye. A screen for Leber hereditary optic neuropathy ( LHON) revealed the presence of the 11778 mutation. LHON is a hereditary form of optic neuropathy associated with sudden and severe visual loss, dense central scotomas, and typical optic disc appearance. Different MRI findings have been shown in various reports. In one study ( 1), MRI demonstrated enhancement of the optic nerve during or shortly after the acute phase of visual loss in one -••- <-:^ d FIG. 4 Visual fields performed 6 months after acute visual loss in the second-affected eye show bilateral inferior altitudinal defects. Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 29 JNeuro- Ophthalmol, Vol. 23, No. 1, 2003 PHOTO ESSAY patient. On the other hand, Mashima et al ( 2) did not find optic nerve enhancement on MRI in four patients in the acute phase of visual loss. Such enhancement is, of course, not specific to LHON, having been demonstrated in 54% of patients with acute optic neuritis and in 100%> of patients with radiation-induced optic neuropathy ( 3). Disruption of the blood- brain barrier is believed to be the primary pathologic event leading to gadolinium- DTPA leakage and optic nerve enhancement in these cases. We describe high signal on T2 MRI in the optic chiasm long after acute visual loss in LHON, a finding not previously reported. Earlier reports ( 2,4) have described similar MRI findings limited to the optic nerves. Mashima et al ( 2) found increased signal in the orbital optic nerves on L2 fat- suppressed sequences in the atrophic stages of LHON. Kermode et al ( 4) also showed increased T2 signal in the intraorbital sections of the optic nerve. Conversely, high T2 MRI optic nerve signal is not often found in the atrophic phase of LHON. Dotti et al ( 5) studied 15 LHON patients at different stages of the illness and found no consistent MRI signal abnormalities. Our patient demonstrated T2 high signal in the optic chiasm on the side of the atrophic optic nerve 3 months after the first attack. The MRI performed 6 months after the second attack, when both optic nerves were atrophic on clinical examination, revealed T2- weighted hyperintense signals on both sides of the optic chiasm. This T2 high signal is thought to represent Wallerian degeneration. The signal increase comes from gliosis, together with loss of normal optic nerve tissue and its replacement by water. In LHON, severe axonal degeneration with demyelination of the pre-geniculate pathway is a constant postmortem finding ( 6,7). REFERENCES 1. Vaphiades MS, Newman NJ. Optic nerve enhancement on orbital magnetic resonance imaging in Leber's hereditary optic neuropathy. J Neuro- Ophthalmol 1999; 19( 4): 238- 9. 2. Mashima Y, Oshitari K, Imamura Y, et al. Orbital high resolution magnetic resonance imaging with fast spin echo in the acute stage of Leber's hereditary optic neuropathy. J Neurology Neurosurg Psy-chiatry 1998; 64: 124- 7. 3. Guy J, Mancuso A, Quisling RG, et al. Gadolinium- DTPA-enhanced Magn Reson Imaging in optic neuropathies. Ophthalmology 1990; 97: 592- 600. 4. Kermode AG, Moseley IF, Kendell BE, et al. Magnetic resonance imaging in Leber's optic neuropathy. JNeurology NeurosurgPsychiatry 1989; 52: 671- 4. 5. Dotti MT, Caputo N, Signorini E, et al. Magnetic resonance imaging findings in Leber's hereditary optic neuropathy. Eur Neurol 1992; 32: 17- 9. 6. Adams JH, Blackwood W, Wilson J. Further clinical and pathological observations on Leber's optic atrophy. Brain 1966; 89: 15- 26. 7. Kwittken J, Barest HD. The neuropathology of hereditary optic atrophy ( Leber's disease): the first complete anatomic study. Am J Pathol 1958; 34: 185- 207. Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 30 © 2003 Lippincott Williams & Wilkins |