C-arm fluoroscopy for the removal of an intraorbital foreign body in a cat

Abstract

This report describes the clinical manifestations, diagnosis and minimally surgical intervention of a cat with an intraorbital foreign body. A spayed female cat of unknown age was presented with a recurrent cutaneous sinus tract of the left suborbital region. The cat had not vocalized at all since the adoption. A sharp-edged radiopaque foreign body was visualized on dental radiography. Computed tomography outlined the length of the foreign body from the intraorbital soft tissue to the pharynx. The foreign body was removed under the guide of C-arm fluoroscope with minimal skin incision. The surgical site healed completely on the 11th postoperative day, and the cat vocalized normally after healing.

Many clinical conditions induce periorbital inflammation, including foreign bodies and periapical abscesses. Among them, the foreign bodies resulting in periorbital inflammation may be left in place if the removal could result significant damage, because maxillofacial and intraorbital regions are complicated with various muscles, nerves and vessles. ¹ The clinical manifestations and prognosis of these conditions are diverse depending on the causes. Lead foreign bodies may be tolerated by the body; however, iron and copper may produce toxic ions as a side effect. Organic materials including plant material and wood may directly irritate tissues and may serve as a receptacle for bacterial or fungal infection due to the structures. ² In general, acute foreign body associated inflammation can resolve with object removal; however, several cases were reported that organ function could not be retrieved by physical destruction or inflammatory reaction. ³

Metal foreign bodies are easily identified on different types of diagnostic modalities. Among them, computed tomography (CT) commonly used to identify the exact location of the metal foreign body prior to surgery; however, intra-operative use can be cumbersome. Successful foreign body removal in complicated surgical areas such as intraorbital region includes exact confirmation of location of the foreign body and minimally-invasive surgical manipulation. This report described a suborbital cutaneous sinus tract and intraorbital foreign body penetrating through pharynx in a non-vocalizing cat and its effective removal using C-arm fluoroscopy.

A spayed female Persian-Chinchilla cat of unknown age (3.2 kg) was presented with recurrent cutaneous sinus tract of the left suborbital region to the Veterinary Medical Teaching Hospital of Seoul National University (Fig 1a). The cat had been discovered as a stray and was adopted 1 year prior to present with no clinical history. There was no history of trauma; the cat had not vocalized in the past year. The cutaneous lesion was originally identified 6 months prior to presentation, and underwent repeated inflammation and resolution depending on antibiotic administration. General physical and ophthalmic examinations did not reveal any abnormalities in the cat. Dental examination demonstrated generalized dental calculus (grade 1–2) and gingivitis (grade 1) without tooth mobility. The cat did not demonstrate pain on percussion of the left maxillary teeth. ⁴

Fig 1

Clinical features and diagnostic images of the intraorbital foreign body (a) A cutaneous fistula was visualized in the left suborbital region. (b) A radiopaque linear foreign body was identified above the third maxillary premolar tooth. (c) The foreign body with radial artifacts was located in the sub-ocular space. (d) A three-dimensional CT image identified the foreign body from orbital limb to the pharyngeal region.

Blood analysis and thoracic radiography values were within normal ranges. Dental radiography; (Dent-x Ardet, Milano, Italy) was performed on the left maxillary premolars under general anesthesia to rule out periapical abscesses. Anesthesia was induced with propofol (6 mg/kg intravenous (IV); Provive, Claris, Ahmedabad, India) and was maintained with isoflurane (Forane; Choongwae pharma, Seoul, Korea) and 100% oxygen. The radiography did not demonstrate periapical changes; however, a linear and sharp-edged radiopaque foreign body was identified above the left maxillary third premolar tooth dorsal space (Fig 1b). CT (GE CT/e, General electric medical system, Yokogawa, Japan) was performed to determine the exact location of the foreign body. The foreign body passed through the soft tissue of the ventral margin of left orbit to the pharynx; however, the foreign body did not penetrate the globe. Transverse CT images demonstrated radial artifacts around the foreign body and increased surrounding tissue opacities after injection of IV contrast (Fig 1c). Three-dimensional images revealed that the cranial tip of the foreign body reached up to the dorsal edge of the left zygomatic bone, and the body was located just inside of the orbit (Fig 1d). Based on the radiological findings, the draining tract was suggested developing secondary to a metallic foreign body in the orbit.

The area around the cutaneous sinus tract was clipped and the orifice was extended 1 cm with a lateral incision to remove the foreign body; however, a tip of the foreign body was not identified. And greater dissection into the orbit had significant risk. Therefore, the C-arm fluoroscope (KMC-950, Comed medical systems, Seongnam, Korea) was employed in an intermittent fashion for minimally-invasive surgical intervention. The origin was carefully explored using a Kirschner wire via the skin incision and a straight mosquito hemostat was used for foreign body retrieval with no further dissection (Fig 2a–c). The foreign body was a 3.5 cm needle used for sewing cloths and the tip was pointed toward suborbital skin (Fig 2d). The canal was confirmed by connecting through the pharynx with a sterile saline flush. The incision area was sutured with 4-0 nylon (Blue Nylon, Ailee, Busan, Korea) after lavage. After surgery, amoxicillin–clavulanate (12.5 mg/kg dose, Clavamox drops, Pfizer animal health, New York, USA) was administrated twice per day orally for 7 days. The surgical site was completely healed on the 11th postoperative day and the cat began vocalizing normally postoperatively. There were no complications until 1 year postoperatively.

Fig 2

Foreign body removal was performed under the guide of C-arm fluoroscopy (a) The foreign body location was confirmed. (b) Surgical exploratory procedures were performed along the tract with an orthopedic pin. (c) The foreign body was completely removed. (d) The foreign body was identified as a sewing needle.

The facial cutaneous sinus tracts likely occur due to periapical abscesses, dermoids, regional infections and foreign bodies in small animals. ^5–8 Among them, suborbital cutaneous sinus tracts were considered typical manifestations of periapical abscesses. ⁹ Therefore, dental examination of the present case including dental radiography was important to assess the lesion. Although the present case did not show periapical abscess, the dental radiography could incidentally reveal the cause of cutaneous sinus tract as a foreign body. However, there were not shown the exact location of the entire foreign body on dental radiography, CT was performed to accurately determine the nature of the foreign body.

Several orbitotomy techniques were applied for surgical removal of the orbital foreign body, but were typically used in dogs. ^10,11 Among them, the lateral approach provided the best exposure for deep access to the ventral orbit. However, the orbitotomy is quite invasive and time-consuming. Additionally, the feline orbit has little free space and composed bony walls compared to dogs; therefore, orbital exploration is restricted and partial orbitotomy may not offer sufficient visualization. ^12,13 For these reasons, intra-operative ultrasonography and endoscopy have been reported as useful aids in the intraorbital foreign body removal. ^11,14 However, these instruments can be inconvenient and may crowd surgical fields. ¹ Considering these aspects, C-arm fluoroscopy could be suitable for intra-operative radiopaque foreign body removal as intra-operative fluoroscopy can provide real-time feedback on spatial changes between surgical instruments and foreign bodies. Fluoroscopy has some side effects such as irradiation, but under normal working exposure (frame rate=30 frames/s), 1 min irradiation with fluouroscopy is equivalent to approximately 12 conventional radiographs of the same structure. ¹⁵ The foreign body was not detected in the present case during surgical exploration along the tract after the lateral incision, and additional dissection was not recommended due to the presence of suborbital vessels, nerves and muscles. However, intermittent use of the C-arm fluoroscope rapidly enabled facilitative retrieval of the foreign body without excessive dissection and hemorrhage.

Vocalization results from motor coordination of the mouth-opening, perioral, tongue, pharyngeal, laryngeal and abdominal muscles. ¹⁶ CT scans of the present case demonstrated that the foreign body had penetrated through the pharynx and the surrounding tissue was vascularized secondary to inflammatory reactions. According to these results, the lack of normal pre-surgical vocalization was likely secondary to pharyngeal pain from the foreign body. In addition, the needle direction pointed external skin, suggesting that the foreign body originated in the oral cavity, passed through the pharyngeal soft tissue and eventually reached suborbital region. It was reported that plant material occasionally entered the orbit by penetrating through the pterygopalatine fossa from the mouth in cats. ¹⁷ Considering direction of the needle, this case was suggested going through the same root.

The present case described successful minimal invasive surgery using a suitable intra-operative imaging unit for the removal of a poorly-visualized foreign body. The procedure had several benefits such as less time-consuming, less hemorrhage and less tissue damage than orbitotomy. Although this technique may be limited to radiopaque materials, C-arm fluoroscopy may serve as a non-invasive and useful therapeutic modality in foreign body removal.