Case 12004 Radio-induced optic neuropathy

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haemorrhage due to radiation-induced vasculopathy [9]. Optic neuropathy (ON) ... Area of Interest: Neuroradiology peripheral nerve;. Imaging Technique: MR;.

Case 12004 Radio-induced optic neuropathy Ammor H, Boujarnija H, Fikri G, Lamrani Y, Boubbou M, Kamaoui I, Tizniti S, Maaroufi M Section: Head & Neck Imaging Published: 2014, Aug. 1 Patient: 48 year(s), female

Authors' Institution Department of Radiology, CHU Hassan II Fes Fes, Morocco; Email:[email protected]

Clinical History A 48-year-old woman, followed-up in the radiotherapy service for undifferentiated carcinoma of the nasopharynx (UCNT), handled by concomitant radiochemotherapy and presented 15 months after the end of the treatment with reduction in left visual acuteness.

Imaging Findings Cerebral MRI was made and showed a small hypertrophy of the left second nerve in its pre-chiasmatic portion which showed hyperintense signal on T2WI, and enhanced after injection of gadolinium.

Discussion Radiation-induced optic neuropathy (RION) is a rare but generally disastrous repercussion of radiation to the optic pathways. It is essentially an exclusive iatrogenic phenomenon, arising in patients who have had radiation therapy for neoplasms and other lesions in locations near the visual

apparatus [1]. The mechanism of this entity implies direct damage to macromolecules and formation of free peroxide and superoxide radicals, especially in the presence of oxygen [2]. Pathologic specimens of involved optic nerve show ischaemic demyelination, axonal loss, reactive astrocytosis, endothelial hyperplasia, oblitrative endarteritis and fibrinoid necrosis [3-5]. Typically, this pathology presents with acute painless visual loss in one or both eyes. Presentation time of visual symptoms varies from 3 months to 8 years after radiotherapy; nevertheless, nearly all cases arise in the course of 3 years after radiotherapy, with a peak at 1.5 years [3]. MRI is the investigation of choice for diagnosing radiation injury to the visual pathway, and may show abnormalities before the loss of vision. The development of FATSAT techniques and the use of paramagnetic contrast solutions allow good exploration of the optic chiasm and also intraorbital and intracranial parts of the optic nerve. Typically, on T1WI there is no anomaly. After injection, the optic nerve will show enhancement [6]. Enlargement of the optic nerve has also been reported in the literature [7, 8], it may be explained by haemorrhage due to radiation-induced vasculopathy [9]. Optic neuropathy (ON) covers many clinical entities (inflammatory, ischaemic, post-radiation, ...) [10]. Unilateral ON is more suggestive of an inflammatory, ischaemic, post-radiation, traumatic, or compressive process, while bilateral ON generally suggests a toxic, hereditary or metabolic origin [10]. Pain on eye movement associated with a rapid vision loss and a normal fundus is specific of optic neuritis [10]. RION is generally maximum at onset, while Inflammatory ON frequently worsens over a short period of time [10]. The use of DWI to explore the optic nerve is rarely mentioned in the literature. Some authors noted that ADC was increased in the acute inflammatory phase but decreased in the chronic phase of optic neuritis. Recently, the introduction of fat and CSF-suppressed zonal oblique multi-section echoplanar imaging (ZOOM-EPI) sequences has revolutionized the exploration of the optic nerve [11-13]. This technique has been applied by Al-Shafai and Mikulis to a patient with an acute ischaemic ON; the optic nerve of this patient showed decreased ADC [14]. Systemic corticosteroid and hyperbaric oxygen are used for management of this disorder, but the results are discouraging [2]. Prevention of this disorder seems to be more efficient (reduction of radiation doses, daily fractionation of radiotherapy, exact focusing of radiation beam on target tissue, usage of stereotactic methods of radiotherapy...) [2].

Final Diagnosis Radio-induced optic neuropathy

Differential Diagnosis List Arteritic ischaemic optic neuropathy, Nonarteritic ischaemic optic neuropathy

Figures Figure 1 Cerebral MRI

Cerbral MRI: coronal T2: Discreet hypertrophy of the pre-chiasmatic portion of the left optic nerve which is hyperintense. © Tizniti S, Department of Radiology, CHU Hassan II, Fes, Morocco

Area of Interest: Neuroradiology peripheral nerve; Imaging Technique: MR; Procedure: Diagnostic procedure; Special Focus: Pathology;

NECT: axial T1 FATSAT: there is no anomaly of signal in the left optic nerve.

© Tizniti S, Department of Radiology, CHU Hassan II, Fes, Morocco

Area of Interest: Neuroradiology peripheral nerve; Imaging Technique: MR; Procedure: Diagnostic procedure; Special Focus: Pathology;

CT: axial T1 FATSAT after injection of gadolinium: the pre-chiasmatic portion of the left optic nerve is enhanced after injection of gadolinium. © Tizniti S, Department of Radiology, CHU Hassan II, Fes, Morocco

Area of Interest: Neuroradiology peripheral nerve; Imaging Technique: MR; Procedure: Diagnostic procedure; Special Focus: Pathology;

CT: coronal T1 FATSAT after injection of gadolinium the pre-chiasmatic portion of the left optic nerve is enhanced after injection of gadolinium. © Tizniti S, Department of Radiology, CHU Hassan II, Fes, Morocco

Area of Interest: Neuroradiology peripheral nerve; Imaging Technique: MR; Procedure: Diagnostic procedure; Special Focus: Pathology;

References [1] Richard L Levy and Neil R Miller. (2006) Hyperbaric Oxygen Therapy for Radiation-induced Optic Neuropathy Ann Acad Med Singapore 35:151-7. [2] Pakravan et al. (2008) Radiation Chiasma Neuropathy after Radiotherapy for Treatment of Paranasal Sinus lymphoma Iranian Journal of Ophthalmology 20(4):44-48. [3] Miller NR et al (2005) clinical neuro-ophthalmology vol. 1, 6th ed. 7: 374-6. [4] Albert Jakobiec. (1994) Principles and practice of ophthalmology vol. 4, chap. 211: 2680. [5] William Tasman, Edward A. Jaeger (2005) Duane's clinical ophthalmology vol 2, chap. 5: 76. [6] Danesh-Meyer HV (2008) Radiation-induced optic neuropathy J Clin Neurosci. 15(2):95-100. [7] Tartaglino LM, Rao VM, Markiewicz DA (1994) Imaging of radiation changes in the head and neck Semin Roentgenol 29:81-91 [8] Saremi et al. (2005) MRI of Cranial Nerve Enhancement. AJR 185:1487-1497. [9] Barry M Rabin (1996) Radiation-induced Changes in the Central Nervous System and Head and Neck RadioGraphics 16:1055-1072.

[10] V. Touitou*, P. LeHoang. (2012) Diagnostic approach in optic neuropathy Revue neurologique 168:691-696. [11] Wheeler-Kingshott C,Parker G,Symms M,et al. (2002) ADC mapping of the human optic nerve : increased resolution, coverage, and reliability with CSF suppressed ZOOM-EPI Magn Reson Med 47:24-31. [12] Freeman A et al. (1998) Diffusion weighted EPI of the human optic nerve at 3T Proc Intnl Soc Mag Reson Med 6:I265. [13] Hickman S et al (2005) Optic nerve diffusion measurement from diffusion-weighted imaging in optic neuritis American Journal of Neuroradiology 26:951-956. [14] L.S. Al-Shafai and D.J. Mikulis (2006) Diffusion MR Imaging in a Case of Acute Ischemic Optic Neuropathy AJNR Am J Neuroradiol 27:255-257

Citation Ammor H, Boujarnija H, Fikri G, Lamrani Y, Boubbou M, Kamaoui I, Tizniti S, Maaroufi M (2014, Aug. 1) Radio-induced optic neuropathy {Online} URL: http://www.eurorad.org/case.php?id=12004

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