Intraorbital wooden foreign body detected by computed tomography and magnetic resonance imaging

Abstract

To identify and localize an intraorbital wooden foreign body is often a challenging radiological issue; delayed diagnosis can lead to serious adverse complications. Preliminary radiographic interpretations are often integrated with computed tomography and magnetic resonance, which play a crucial role in reaching the correct definitive diagnosis. We report on a 40 years old male complaining of pain in the right orbit referred to our hospital for evaluation of eyeball pain and double vision with an unclear clinical history. Computed tomography and magnetic resonance scans supposed the presence of an abscess caused by a foreign intraorbital body, confirmed by surgical findings.

Introduction

To identify and localize an intraorbital wooden foreign body is often a challenging radiological issue, despite modern high resolution imaging and especially when the clinical history is unclear.

Usually the reported mean time occurring between the presumed injury and the final diagnosis of retained wooden foreign body ranges from 24 h up to 17 months.^1–3

The presence of an intraorbital wooden body commonly occurs after a traumatic incident during work manoeuvres or sport activities; sometimes a specific event is not referred by the patient and the aetiology remains unknown.^1–7

Delayed diagnosis can lead to serious adverse complications; anecdotally, the death of King Henry II of France occurred in 1559 because of a cerebral abscess resulting from an orbital infection due to a wooden body after a jousting tournament.⁸

For this reason clinical suspicion, proper radiological imaging and a skilled surgeon are warranted for this scenario.

The goal of the clinical management includes reacquiring the visual functions without ocular motility deficits and resolution of pain, inflammation and eyelid abnormalities.

Case report

A 40 years old male complaining of pain in the right eye was referred to our hospital for evaluation of eyeball pain and double vision. He did not refer a clear clinical history because he was not able to communicate in Italian or English; however, he had been injured in his right eye during a street scuffle and he had been diagnosed with a right conjunctival laceration.

Limited adduction in the upper direction was observed in the right eye.

After slit-lamp examination, when no foreign body was found, his lacerated conjunctiva was sutured.

Although there was a strong clinical suspicion of a foreign body in the orbital region, standard imaging studies (orbital plain X-rays and ocular echography) did not detect any fragments.

Because of the ongoing nature of the symptoms (ocular pain, palpebral oedema and erythema) without improvement of the vision and of the eye motion, further detailed studies with computed tomography (CT) and then magnetic resonance (MR) scans were performed (Figures 1–3): these detected a linear structure in a mass context infiltrating eyelid, internal rectal muscle and intraconic fat; furthermore it distorted the physiological architecture of the ocular globe, not allowing distinction from the sclera and displacing the optic nerve, with apparent oedema of the surrounding fat tissue.

Figure 1.

Not-enhanced computed tomography in axial (a), sagittal (b) and coronal (c) planes showing a linear hyperdense lesion in the context of a mass of different densities, located into the postero-medial compartment of the right orbit and compressing the eyeball.

Figure 2.

Not-enhanced magnetic resonance: (a) axial T1-w SE, (b) axial T2-w TSE, (c) coronal T2-w TSE, (d) axial T2-w TSE with fat saturation. Magnetic resonance images confirm the computed tomography findings, demonstrating a well delineated stick-shaped lesion without signal (wooden body) in the postero-medial compartment of the right orbit with isointense tissue surrounding.

Figure 3.

Enhanced T1-w SE magnetic resonance sequences after endovenous gadolinium injection in axial (a) and sagittal (b) planes and axial diffusion weighted b = 1000 sequences (c) showing not-enhancing linear hypointense tissue without restriction of the diffusion signal, surrounded by fat tissue with dishomogeneous enhancement expression of inflammatory phenomena.

Thus an orbital abscess in the right eye was strongly suspected.

A new surgical exploration was performed and finally it yielded an intraorbital wooden foreign body in the posterior extraconal space, corresponding to the linear structure identified by the MR scan (Figures 2 and 3).

The patient was discharged after two days under antibiotic coverage and tetanus prophylaxis and after one month he fully recovered and regained visual acuity of 20/20.

Surgical intervention description

Fibrous adipose tissue was found with intense and predominantly acute flogosis and abscessualization areas.

Extraneous material was composed of inorganic material.

An ovular, capsular, concamerated mass, measuring approximately 4 cm and located below the elevator muscle of the superior eyelid was then removed, composed of fluid contents frankly corpuscolated.

It fitted strongly to the contiguous soft tissues, extrinsic ocular muscles and to the vessel and nerves of the anatomic region due to repeated, previous inflammatory reactions extending to the deeper portion of the orbit. Posteriorly there was evidence of tissue with hard wooden solidity; a wooden foreign body, measuring approximately 10 mm × 30 mm, was from the posterior compartment.

Discussion

Penetrating orbito-cranial injuries caused by intraorbital foreign bodies are a rare cause of morbidity, being more common among young people. The term intraorbital foreign body refers to a foreign body that occurs within the orbit but outside the orbital globe.

Orbital organic foreign bodies can lead to potentially serious orbital and intracranial complications.

Intraorbital foreign bodies are elusive and demand a low threshold for further imaging.

Accurate positioning of the foreign body before removal is essential in the craniofacial region;^4–7 sometimes retrieval of a foreign body may be challenging because of many influencing factors including: size of the object, site and surrounding anatomic structures.

The detection is sometimes difficult especially when the clinical history is unclear, the ophthalmologic exam reveals no abnormalities or if the patient is referred to the hospital several months after the assumed traumatic event.³

In this reported case CT clearly showed a linear lucent lesion in the context of a mass of different densities (Figure 1).

MR revealed a well delineated stick-shaped lesion, hyperintense in T1-weighted sequences and hypointense in T2-weighted sequence and FLAIR in the posterior compartment (Figures 2 and 3).

Early surgical extraction of the foreign body under general anaesthesia had a decisive role on the patient’s full recovery.

Different onset signs and symptoms can be related to a penetrating foreign body in the ocular compartment, including motility disturbance, conjunctival injection with or without discharge, decreased vision, draining fistula and localized pain or sensation of tightness in the eyelid.^1,3 Uncommon symptoms include proptosis, ptosis, lower eyelid retraction and pain on ocular movement.

The majority of the subjects present within 24 h from the injury.

Foreign bodies are found mainly within the orbit in the superior, medial and inferior compartments; less frequently in the posterior and lateral regions.^6,7

Preliminary radiographic interpretations are often integrated with CT and MR scans, which allows a definite diagnosis.^1,3,7

Young men, as in this case report, are at particularly high risk for wooden intraorbital foreign body.

In patients with a known site of penetration, almost half of the cases occur in the conjunctiva, notably without presence of eyelid laceration, emphasizing the need to check the conjunctiva and fornices closely.

CT and MR are often extremely helpful in distinguishing a retained wooden foreign body from other low-density signals of air or fat.

Compared with MR, CT is performed first in the acute phase and gives relevant information about the localization into the orbit and the nature of the foreign body by measuring its Hounsfield Units; on the other hand, MR is required to properly distinguish the fragment from the surrounding tissue’s inflammatory reaction as well as to evaluate the extent of the abscess itself.

It is important to have a properly worded consent that includes the possibility of residual wooden foreign bodies and the need for subsequent surgical exploration.

Patients usually present a favourable outcome after surgery and antibiotics therapy.³

Conclusion

X-rays and orbital ultrasound do not always result in an appropriate diagnosis of intraorbital foreign body.

A detailed CT scan is able to detect a wooden foreign body as a linear dense structure surrounded by a soft tissue mass with density similar to that of muscle or as a lucent lesion with nearly the same density as air or fat.

MR scans as well are useful to delineate the orbital wooden foreign body, presenting with a different signal from the surrounding inflammatory mass.

A written informed consent for the patient information and images to be published was provided by the patient. This research was conducted according to the World Medical Association Declaration of Helsinki.

Conflict of interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.