Optic nerve injury secondary to endoscopic sinus surgery: an analysis of three cases

Type IV optic nerve and Onodi cell: is there a risk of injury during sphenoid sinus surgery?

Objective

This study aims to determine the prevalence and types of Onodi cells through computed tomography and investigate the relationship between Onodi cell and the surrounding structures, paying particular attention to the risky proximity to the optic nerve canal.

Methods

In this study, 430 computed tomography scans of paranasal sinuses were analysed to establish the prevalence and different types of Onodi cells. Furthermore, the relationship between Onodi cell and different patterns of sphenoid sinus pneumatisation and surrounding structures were investigated. Special attention was paid to the relationship between Onodi cell and the optic nerve canal, particularly in cases when the optic nerve canal was bulging by more than 50% into the Onodi cell (Type IV).

Results

The Onodi cell was detected in 21.6% of cases, with the most common being Type I (48.5% right, 54.3% left). Type IV bulging of the optic nerve canal into the Onodi cell was observed in 47.1% of cases on the right side, 41.2% on the left side and bilateral in 11.7% of cases.

Conclusions

In our series, we observed a high prevalence of Type IV optic nerve bulging into the Onodi cell. For this reason, we suggest that clinicians should always try to identify it in a pre-operative setting with computed tomography to avoid catastrophic consequences during endoscopic sinus surgery approaching the sphenoid area.

Anatomy and Variations of Onodi Cells and Haller Cells: A HRCT Cum Clinical Analysis in Sinonasal Disease and Polyposis

The Onodi cell is defined as the posterior-most ethmoid cell. Haller cells are defined as infraorbital ethmoid cells. HRCT scanning provides excellent bone detail and accurate soft tissue mapping. The aim of this study is to know the prevalence of Haller cells and Onodi cells and to find variations in them on HRCT. Also to find co-relation between HRCT findings and Intra operative findings. A Hospital based prospective and cross-sectional study which included 30 patients above 15 years of age coming to ENT OPD with complaints related to sinonasal disease and polyposis;willing for HRCT followed by operative procedures. A total of 30 patients are included in the study. The mean age was found to be 38.70 ± 14.37. Prevalence of haller cells and onodi cells was 30% and 33.3% respectively. Statistical significance was found between association of haller cells with sinusitis. Intra-operative findings corresponded to 8 out of 9 HRCT findings (p-value = 0.001). We conclude that the actual prevalence of haller cell and onodi cell is best noted on HRCT-PNS and this holds a significant role in imparting thorough knowledge of the anatomical variations of PNS and hence preventing intraoperative complications due to presence of these variant cells.

Is there a relationship between Onodi cell and optic canal?

OBJECTIVES

We investigated the relationship between Onodi cells and optic canal by paranasal sinus computed tomography (PNSCT).

METHODS

In this retrospective study, 508 PNSCT (265 males and 243 females) was examined. Onodi cell presence, pneumatization types, optic canal types; and also sphenoid sinusitis and anterior clinoid process pneumatization were evaluated.

RESULTS

The prevalence of Onodi cells was 21.2% of the patients. Onodi cells were observed 40.7% on the right side and 25.9% on the left side. In 33.4% of the patients, bilateral Onodi cells were present. Male/Female ratio was 24.5%/17.6%. Onodi cell types were detected as Type I > Type II > Type III bilaterally. There was a positive correlation between the right and left Onodi cell types (p < 0.05). Optic canal types were detected as Type IV > Type I > Type II > Type III. bilaterally. There was a positive correlation between right and left optic canal types. Onodi cell presence and ACP pneumatization were found as statistically significant (p < 0.05). In 65.5% of the patients, Onodi cells and ACP pneumatization were absent. ACP pneumatization was present in 35.4% of the cases. In nine cases, bilateral Onodi cells and ACP pneumatization were detected. Sphenoid sinusitis was detected in 11.4% of Type I and 13.8% of the Type II Onodi cells on the right side. On the left side, it was detected in 12.9% of the Type I and 19.0% of Type II Onodi cells.

CONCLUSION

Identification of Onodi cell is very important clinically because of its proximity to optic nerve canal. We concluded that type IV Onodi-optic canal relationship was the most common finding in our study. Onodi cell presence and their patterns of pneumatization must be evaluated on PNSCT preoperatively to avoid optic canal damage.

The prevalence of the Onodi cell - Most suitable method of CT evaluation in its detection

BACKGROUND

The Onodi cell (sphenoethmoidal air cell) is an anatomic variant of the most posterior ethmoid cell that pneumatised superiorly and laterally to the sphenoid sinus, and is in close relation to the optic nerve. The proper identification of the Onodi cell is essential during a pre-operative computer tomography (CT) examination, as the presence of that ethmoid cell variant makes sphenoid sinus surgery more risky. The bulging of the optic nerve to the ethmoid cell wall is well visualized during endoscopic examination, but there are no clearly defined criteria for a potentially dangerous Onodi cell type in CT examinations.

OBJECTIVE

To determine the prevalence and types of Onodi cell in CT examination and find the most suitable CT scanning planes to identify it.

MATERIAL AND METHODS

Three plane (axial, coronal and sagittal) reconstructions of 196 paranasal sinuses were analyzed. The most posterior ethmoid cell was classified into four types, according to its position in relation to the sphenoid sinus and the optic nerve canal bulging into the lumen of the sphenoethmoid cell.

RESULTS

The Onodi cell was detected in 39.8% of cases, although in 55.6% of cases a direct contact between the most posterior ethmoid cell and the optic nerve was present. Bulging of the optic nerve canal was seen in 25% of cases. In two cases two posterior ethmoid cells were in direct contact with the optic nerve canal.

CONCLUSION

The prevalence of the Onodi cell was higher than previously reported. Pre-operative paranasal sinuses CT examination should be evaluated in all three planes (axial, coronal and sagittal) to avoid missing or over-detection of the Onodi cell. Axial and sagittal planes are preferable for the detection of the Onodi cell.

Traumatic optic neuropathy: a review

The aim of this article is to evaluate current literature on investigation and management of traumatic optic neuropathy (TON), propose recommendations for diagnosis and management, and explore novel future treatments. TON, though uncommon, causes substantial visual loss. Without clear guidelines, there is much ambiguity regarding its diagnosis and management. Investigation and treatment (conservative, medical, surgical, and combined) vary widely between centers. Electronic databases PubMed, MEDLINE, PROSPERO, CENTRAL, and EMBASE were searched for content that matched "Traumatic optic neuropathy." Articles with abstracts and full text available, published in the past 10 years, written English and limited to human adults, were selected. All study designs were acceptable except case reports and case series with fewer 10 patients. All abstracts were then evaluated for relevance. References of these studies were evaluated and if also relevant, included. A total of 2,686 articles were retrieved and 43 examined for relevance. Of these, 23 articles were included. TON is a clinical diagnosis. Visual-evoked potential is useful in diagnosis and prognosis. Computed tomography demonstrates canal fractures and concomitant injuries. Magnetic resonance images should be reserved for select and stable patients. Conservative treatment is appropriate in mild TON. Steroids are of questionable benefit and may be harmful. Surgery should be reserved for patients with radiological evidence of compression and individualized.

Complications of vision loss and ophthalmoplegia during endoscopic sinus surgery

OBJECTIVE

To describe two rare cases of concurrent vision loss and external ophthalmoplegia following powered endoscopic sinus surgery (ESS).

DESIGN

Observational case report.

RESULTS

The records of two patients who underwent powered ESS and developed multiple concurrent ophthalmic complications were retrospectively reviewed for clinical history, neuro-ophthalmologic examination, and imaging findings. Patient 1 developed a retinal vascular occlusion and complete loss of adduction. Patient 2 developed an orbital hemorrhage, optic neuropathy, and a restrictive global ophthalmoplegia. Similar published case reports were also reviewed.

CONCLUSION

Despite advances in powered ESS technique and instrumentation, serious ophthalmic complications can still occur. Inadvertent entry into the medial orbital wall can result in a combination of blindness and ocular motility dysfunction. The variety of mechanisms responsible for these complications underscores the importance of thorough pre- and postoperative clinical examination and review of imaging studies.

Sphenochoanal polyps and the optic nerve

Isolated sphenoid pathology is uncommon. Nasal polyps that originate from the anterior wall of the sphenoid sinus and reach the nasopharynx are called sphenochoanal polyps. The atypical location of sphenochoanal polyps leads to misdiagnosis, and surgery risks injuring the surrounding structures, such as the optic nerve, carotid artery, and brain. For the differential diagnosis of sphenochoanal polyps, nasal endoscopy and computed tomography are very important. We present the clinical and radiological features of a sphenochoanal polyp and review the status of the optic nerve during endoscopic surgery for a sphenochoanal polyp.

Permanent blindness after endoscopic sinus surgery

Few cases of ophthalmic complications have been reported following sinus endoscopic surgery with current techniques. Irreversible damage to orbital structures was found in a 21-year-old patient referred to our department for evaluation after sinus endoscopic surgery and ipsilateral amaurosis.

Visual recovery after direct traumatic optic neuropathy

Direct traumatic optic neuropathy is a rare complication of endoscopic sinus surgery and can result in irreversible damage to the optic nerve. We report a case of direct traumatic optic neuropathy after transnasal endoscopic orbital decompression for Graves's disease in a patient who experienced near-complete recovery of vision. We discuss possible mechanisms.