Presumed Optic Nerve Sheath Meningioma Presenting With Relapsing-Remitting Course and Periorbital Pain

Optic nerve sheath meningiomas (ONSM) typically present with slowly progressing visual loss (1). We aim to expand the literature on ONSM by describing a middle-aged man with final diagnosis of presumed ONSM, who presented with severe relapsing-remitting episodes of periocular pain, brief improvement of vision with corticosteroids, and fluctuating pattern of optic nerve enhancement and enlargement on neuroimaging. A 59-year-old man noticed right retrobulbar pain and blurry vision in the right eye. He described the pain as severe, constant, and not worsened with eye movements. He had a history of migraines with aura, but was otherwise healthy and did not take any medications. Nine and then 4 years ago, he experienced sudden onset of blurry vision and vertical diplopia associated with headache and was diagnosed with right fourth nerve palsy. MRI brain performed during these episodes reportedly demonstrated mild enhancement of intracanalicular portion of right optic nerve and right cavernous sinus. He was presumptively diagnosed with orbital inflammatory syndrome and treated with intravenous pulse steroids, which led to quick resolution of symptoms. Visual acuity was 20/25 in right eye and 20/20 in left eye, there was right relative afferent pupillary defect. Extraocular motility and alignment testing were normal. Ophthalmoscopy demonstrated right optic nerve pallor. Peripapillary optical coherence tomography (pOCT) showed decreased average retinal nerve fiber layer (RNFL) thickness in the right eye (See Supplemental Digital Content, Figure 1, https://links.lww.com/WNO/A666). Humphrey Visual Field (HVF) (24-2 algorithm) demonstrated generalized depression in the right eye. MRI of the brain and orbits with contrast showed subtle enlargement and enhancement of distal intra-orbital, intracanalicular and prechiasmatic optic nerve and cavernous sinus on the right side (Fig. 1 and See Supplemental Digital Content, Figure 2, https://links.lww.com/WNO/A667). Lumbar puncture demonstrated normal cerebrospinal fluid (CSF) contents and normal cytology. Neuromyelitis optica and myelin oligodendrocyte glycoprotein antibody titers were negative. He was treated with 3 days of intravenous solumedrol (1 g/day) and discharged with presumed diagnosis of orbital inflammatory syndrome.FIG. 1.: Fat-saturated T1 postgadolinium sequences at initial presentation. Left image, axial image demonstrating enhancement in right optic nerve sheath involving the posterior intraorbital and intracanalicular segments (white arrow). Middle image, coronal image demonstrating circumferential enhancement of the intracanalicular optic nerve segment (white arrow). Right image, mild fulness and questionable enhancement of right cavernous sinus (arrow).He re-presented 3 months later, complaining about worsening vision and periorbital pain. Vision was now 20/40 in the right eye and HVF demonstrated generalized depression with worsening of mean deviation. Treatment with 1 g of intravenous solumedrol for 3 days was given again. This produced resolution of pain, but only mild improvement in vision. MRI of the brain and orbits revealed persistent mild enhancement of right optic nerve in the same location, but decrease in optic nerve caliber (See Supplemental Digital Content, Figure 3, https://links.lww.com/WNO/A668). erythrocyte sedimentation rate, C-reactive protein, Rickettsia titers, hepatitis B and hepatitis C virus antigens, Lyme serology, syphilis antibody screen, serum IgG-4 levels, p-ANCA, c-ANCA, and CSF autoimmune encephalitis panel were all negative. Computed tomography of the body and positron emission tomography scan were normal as well. Treatment with mycophenolate mofetil commenced. Throughout the next year, vision continued to slowly deteriorate. MRI of the brain and orbits with contrast was repeated 10 months after initial presentation and demonstrated more obvious enhancement and mild thickening of right optic nerve sheath in its distal orbital, intracanalicular, and prechiasmatic segments in tram-train pattern. There was also mild dural enhancement along adjacent right lateral planum sphenoidale (Fig. 2).FIG. 2.: MRI orbits (1 and 2) fat-saturated T1 postgadolinium sequences. Coronal (left) and axial (middle) images at presentation show enhancement of prechiasmatic segment of the right optic nerve (white arrow) with subtle adjacent dural tail of enhancement along the right planum sphenoidale (white arrowhead). Coronal (right) show slight improvement in enhancement 2 years after presentation.Final diagnosis of presumed optic nerve sheath meningioma masquerading an orbital inflammatory syndrome was made. Treatment with fractionated stereotactic radiotherapy was performed, but unfortunately did not result in improvement of vision. At the last follow-up 4 years after initial presentation, vision remained unchanged, pOCT showed unchanged RNFL thickness (See Supplemental Digital Content, Figure 1, https://links.lww.com/WNO/A666), and patient continued to complain about constant right-sided headaches. Despite low mortality, ONSM are associated with significant visual morbidity (1). The diagnosis is often delayed resulting in delay in treatment and worse visual prognosis (1–3). We describe a patient with presumed ONSM who was misdiagnosed with orbital inflammatory syndrome because of variability in optic nerve sheath thickening and enhancement, prominent complaint of periocular pain and accompanying subtle fullness and questionable enhancement in cavernous sinus, which likely represented physiologic asymmetry. The initial imaging showed subtle abnormalities involving the optic nerve and cavernous sinus, similar to those noted on the first MRI 9 years earlier. These abnormalities were less prominent on a repeat MRI after treatment with high-dose corticosteroids, although they reverted to the initial pattern on the follow-up imaging. The variability in optic nerve swelling and enhancement led to the conclusion that orbital inflammatory syndrome was the most likely culprit. In retrospect, this variability could have been because of interobserver variability, reduction of perineural inflammation in response to treatment with corticosteroids and intrinsic uncertainty associated with measurement of small tumors, demonstrating importance of interpreting neuro-imaging changes in optic nerves size with caution (3). Another unusual feature of this case was prominent retrobulbar pain. Although the frequency and etiology of pain in patients with ONSM is unknown, it may arise because of direct irritation of trigeminal nerves in the dura by the tumor at the orbital apex, optic canal, or parasellar region. Another possibility is development of secondary migraine-like headache, a common finding in meningiomas, which may be linked to direct irritation of trigeminal endings by molecules secreted by the tumor (4). The relapsing-remitting nature of symptoms separated by several years, as opposed to slowly progressive deterioration typically observed in ONSM, also contributed to misdiagnosis of orbital inflammatory syndrome. It is unclear why the patient remained asymptomatic for many years in-between episodes. One possibility is initial very slow growth of the tumor with episodic inflammation resulting in irritation of sensory structures within the orbital apex. Initial improvement in symptoms after treatment with corticosteroids was also unusual. Although not a common feature, patients with ONSM may demonstrate temporary improvement in vision in response to steroids (5). Although optic nerve biopsy is the gold standard in diagnosing ONSM, it is associated with significant risk of visual morbidity and was declined by the patient (2). Lack of systemic signs/symptoms, and nonrevealing extensive investigations for a secondary etiology excluded other common ONSM mimickers. In conclusion, this case demonstrates diagnostic challenges associated with ONSM: variable optic nerve sheath enhancement on imaging, associated periorbital pain, relapsing-remitting episodes, and temporary improvement following treatment with corticosteroids; thus, ONSM should not be ruled out if these unusual features are present. STATEMENT OF AUTHORSHIP Conception and design: E. Margolin, A. Vosoughi, L. Al Shafai; Acquisition of data: E. Margolin, A. Vosoughi, L. Al Shafai; Analysis and interpretation of data: E. Margolin, A. Vosoughi, L. Al Shafai. Drafting the manuscript: E. Margolin, A. Vosoughi, L. Al Shafai; Revising the manuscript for intellectual content: E. Margolin, A. Vosoughi, L. Al Shafai. Final approval of the completed manuscript: E. Margolin, A. Vosoughi, L. Al Shafai.

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