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Year : 2021  |  Volume : 9  |  Issue : 1  |  Page : 30-32

Onodi cell abscess causing optic neuritis and orbital apex syndrome during pregnancy: A case report

1 Department of Ophthalmology, Eyeris Eye Care, Sainikpuri, Secunderabad, India
2 Department of Ophthalmology, Mediciti Institute of Medical Sciences, Hyderabad, Telangana, India
3 Department of ENT, Star Hospital, Hyderabad, Telangana, India

Date of Submission21-Jan-2020
Date of Decision15-May-2020
Date of Acceptance15-May-2020
Date of Web Publication10-Apr-2021

Correspondence Address:
Harikrishnan Vannadil
Eyeris Eye Care, Sainikpuri, Secunderabad - 500 094, Telangana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcor.jcor_7_20

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Onodi cells are an anatomic variation in the pneumatization of the ethmoidal air cells. Onodi cells can be affected by various pathologies causing optic nerve manifestations. Being a physiologically immunocompromised state, the clinical course of these etiologies varies greatly during pregnancy. When such conditions are manifested during pregnancy, the armamentarium of the clinician is severely restricted both in terms of investigations and treatment. The first suspicion of such a sight-threatening condition relies majorly on clinical examination. Here, we describe the first documented case of Onodi cell abscess-induced optic neuritis in pregnancy managed with methylprednisolone and transsphenoidal surgery.

Keywords: Onodi cell, optic neuritis, transsphenoidal surgery

How to cite this article:
Vannadil H, Jaiswal S, Sistla SK, Bathula S. Onodi cell abscess causing optic neuritis and orbital apex syndrome during pregnancy: A case report. J Clin Ophthalmol Res 2021;9:30-2

How to cite this URL:
Vannadil H, Jaiswal S, Sistla SK, Bathula S. Onodi cell abscess causing optic neuritis and orbital apex syndrome during pregnancy: A case report. J Clin Ophthalmol Res [serial online] 2021 [cited 2022 Jun 27];9:30-2. Available from: https://www.jcor.in/text.asp?2021/9/1/30/313476

The optic canal is surrounded by air cells with the ethmoidal air cells being the most clinically relevant.[1],[2],[3] The ethmoidal air cells are multiple small air pockets within ethmoid bone. However, there exists an anatomical variation wherein there is a large pneumatized air cell located single in the posterior most part of the ethmoid bone called Onodi cell.[1],[4] The Onodi cell pneumatizes laterally and superiorly to the sphenoid air cells.[1] The anatomic location of the Onodi cell is in very close proximity to the optic nerve and occasionally restrict the optic canal making the optic nerve vulnerable.[4] The clinical relevance of the Onodi cell is that any pathology related to this air cell can have a direct impact on the optic nerve leading to ophthalmological effects.[5],[6] Few cases of Onodi cell causing compressive neuropathy have also been reported.[7],[8] Here, we report a case of Onodi cell abscess in a middle-aged female who was pregnant at the time of diagnosis.

  Case Report Top

A 33-year-old female patient, gravida at 33 weeks (G2P1A0 L1), presented to the ophthalmology department with complaints of diminution of vision in the right eye for the past 4 weeks. The patient also complained of right-sided retro-orbital pain on eye movements. There was no other significant history.

On examination, the patient had a best-corrected vision of 20/120 (6/36 or 0.8 logarithm of the minimum angle of resolution [LogMAR]) in the right eye and 6/6 (0.00 LogMAR) in the left. Pupillary examination revealed a relative afferent pupillary defect (RAPD) in the right eye. The extraocular movements were full and free. On slit-lamp examination, the anterior segments of both eyes were within normal limits. Fundus examination revealed an elevated optic nerve head with absent venous pulsations in the right eye [Figure 1]. The optic nerve head of the left eye appeared normal.
Figure 1: Fundus photograph of the patient showing the blurring of margins in the right optic nerve head

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With a presumptive diagnosis of optic neuritis, the patient was subjected to magnetic resonance imaging (MRI) without contrast [Figure 2]. The MRI revealed the presence of Onodi cell in the right side abutting the optic nerve [Figure 2]a, [Figure 2]b and [Figure 2]d. The contents of the Onodi air cell appeared homogenous. The optic nerve was thickened with fat stranding on FLAIR sequence [Figure 2]c.
Figure 2: (a) T2-weighted axial magnetic resonance scan showing Onodi cell (white arrow), (b) T1-weighted sagittal magnetic resonance scan showing the proximity of the Onodi cell to the optic canal (white arrow), (c) flair sequence showing fat stranding in the orbit, (d) T2-weighted coronal magnetic resonance image showing the Onodi cell (white arrow)

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With the concurrence opinion of the treating obstetrician, decision was taken to treat the patient with intravenous methyl prednisolone (IVMP) followed by oral steroids (methylprednisolone) in accordance with prevailing evidence.[9],[10] The patient was explained the risk and benefits of the treatment in the scenario.

At 2-week follow-up after the first dose of IVMP, the visual acuity of the right eye decreased from 20/120 (6/36 or 0.8 LogMAR) to 20/200 (6/60 or 1.0 LogMAR) and the patient developed 15° exotropia of the right eye [Figure 3]. Suspecting an orbital apex syndrome, an ear, nose, and throat consultation was sought. Due to the progressive nature of the condition and profound diminution of vision, surgical intervention was undertaken in the form of transsphenoidal drainage of the Onodi air cell. Intraoperatively, an abscess of the Onodi air cell was found which was drained. The aspirate was sent for microbiological and pathological analysis. However, no organism was identified. The patient was taken up for lower section cesarean section at 38 weeks of gestation, after which the patient was started on broad-spectrum antibiotics with antifungal coverage.
Figure 3: Clinical photograph of the patient showing the involvement of orbital apex. The exotropia is evident

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On 3-month follow-up after the surgical procedure, the vision of the patient in the right eye improved to 20/80 (6/24 or 0.6 LogMAR) with spontaneous correction of squint. The patient is presently stable with no deterioration of vision in the effected eye.

  Discussion Top

Optic neuritis is the term use to describe an inflammatory condition of the optic nerve. With a female preponderance, the incidence varies from 0 · 94 to 2 · 18/100,000/year worldwide.[11] However, in spite of management, many patients suffer from permanent visual deficit due to irreversible damage of nerve fibers.[9],[11] Pregnancy being a physiological immunosuppressive state, it alters the natural presentation and course of many of these etiologies. For instance, there is a decreased incidence of multiple sclerosis-associated optic neuritis with an increased incidence of infectious and vasculogenic optic neuritis.

Onodi cell is an anatomic variation of the ethmoidal air cell with incidence ranging from 8% to 30%.[1],[2] The variation of incidence is likely due to the fact that the imaging is done only on clinical suspicion. Most of the individuals with Onodi cell pneumatization remain asymptomatic, but due to its close proximity to the optic canal and thus the optic nerve, pathologies of the Onodi cell leads to optic neuropathy (inflammatory or compressive) and orbital apex syndromes.[12],[13] Although contrast-enhanced imaging is the investigation of choice, we were restricted to plain MRI due to pregnancy.[14] The fact that the patient developed exotropia subsequently points toward the progression into an orbital apex syndrome. IVMP was administered considering the potential risks. Many recent studies recommend administration of IVMP as a sight-saving measure in spite of the pregnancy status.[14] It is likely that the abscess was infectious. This assumption was supported by gross intraoperative appearance and lack of response to IVMP.

Optic neuritis due to such variations is extremely rare. Being a sight-threatening condition with a potential to cause encephalitis, such conditions must be promptly diagnosed by the treating clinician and simple clinical sign such as RAPD is a satisfactory pointer for further investigation. Even a slight suspicion should be ruled out by MRI promptly. Sight-saving management protocols such as IVMP may be administered in pregnancy after careful weighing of potential risk.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Devaraja K, Doreswamy SM, Pujary K, Ramaswamy B, Pillai S. Anatomical variations of the nose and paranasal sinuses: A computed tomographic study. Indian J Otolaryngol Head Neck Surg 2019;71:2231-40.  Back to cited text no. 1
Lee SH, Yun SJ. Optic neuritis caused by aspergilloma within Onodi cell pyomucocele in a 62-year-old woman. Signa Vitae 2017;13:120-2.  Back to cited text no. 2
Nickerson JP, Lane AP, Subramanian PS, Izbudak I. Onodi cell mucocele causing acute vision loss: Radiological and surgical correlation. Clin Neuroradiol 2011;21:245-8.  Back to cited text no. 3
Ázdemir A, Bayar Muluk N, Asal N, Şahan MH, Inal M. Is there a relationship between Onodi cell and optic canal? Eur Arch Oto Rhino Laryngol 2019;276:1057-64.  Back to cited text no. 4
Mazzurco M, Pavone P, Di Luca M, Smilari P, Pustorino E, Fiumara A, et al. Optic neuropathy, secondary to ethmoiditis, and onodi cell inflammation during childhood: A case report and review of the literature. Neuropediatrics 2019;50:341-5.  Back to cited text no. 5
Gallagher D, Quigley C, Lyons C, McElnea E, Fulcher T. Optic neuropathy and sinus disease. J Med Cases 2018;9:11-5.  Back to cited text no. 6
Yen Nee See W, Sumugam K, Subrayan V. Compressive optic neuropathy due to a large Onodi air cell: A case report and literature review. Allergy Rhinol (Providence) 2016;7:223-6.  Back to cited text no. 7
Tzamalis A, Diafas A, Riga P, Konstantinidis I, Ziakas N. Onodi cell mucocele-associated optic neuropathy: A rare case report and review of the literature. J Curr Ophthalmol 2019, ISSN 2452-2325,https://doi.org/10.1016/j.joco.2019.08.006. Ahead of print.(http://www.sciencedirect.com/science/article/pii/S2452232519300381) [Last accessed on 2021 Jan 25].  Back to cited text no. 8
Mackay DD. Should patients with optic neuritis be treated with steroids? Curr Opin Ophthalmol 2015;26:439-44.  Back to cited text no. 9
Beck RW. The optic neuritis treatment trial: Three-year follow-up results. Arch Ophthalmol 1995;113:136-7.  Back to cited text no. 10
Toosy AT, Mason DF, Miller DH. Optic neuritis. Lancet Neurol 2014;13:83-99.  Back to cited text no. 11
Kwon KW, Oh JS, Kim JW, Yoo RE, Kang JG. Onodi cell mucocele causing isolated trochlear nerve palsy: A case report. Medicine (Baltimore) 2019;98:e15475.  Back to cited text no. 12
Nathe C, Shen EW, Crow R. Complete orbital apex syndrome from an onodi cell mucocele: A case report. J Clin Ophthalmol 2018;2:63-6.  Back to cited text no. 13
Kaplan TB. Management of demyelinating disorders in pregnancy. Neurol Clin 2019;37:17-30.  Back to cited text no. 14


  [Figure 1], [Figure 2], [Figure 3]


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