Salivary fistula after a traumatic injury in the buccal region is not common. It is most commonly encountered in injuries involving the pre auricular region or soft tissues along the course of the parotid duct. It is more frequent in the parotid because its anatomical location is superficial; traumatic salivary fistulae of the other two major salivary glands are rare. This report presents an unusual case of a salivary fistula that occurred following trauma to the infraorbital region and drained into the inferior fornix of the left eye. A review of cases reported in the literature is presented. This is the only case of such a presentation the authors have found after a thorough search of the relevant English language literature.
A 16-year-old female patient presented with pan facial trauma following a road traffic accident. She had a soft tissue laceration transecting the lower eyelid extending to the lower half of the face. There was an orbital blow out fracture with comminuted infraorbital margins and consequent enophthalmos.
After complete preliminary and radiological examination, under general anaesthesia the orbital fractures were reduced and stabilized using 1.5 mm titanium plates. The enophthalmos was corrected with iliac bone grafting to the floor of the orbit.
The postoperative recovery was uneventful until the third week. The patient then complained of epiphora from the affected eye causing dampness of the infraorbital wound ( Fig. 1 ). The nasolacrimal system showed intact canaliculi and drainage on syringing and probing. The patient also reported profuse orbital secretions during mastication. The secretion was collected using a 2 ml syringe with a flexible canula and subjected to biochemical analysis and amylase estimation. The amylase was estimated to be 13,000 units/l. This confirmed the secretion to be saliva. Ultrasound examination showed a salivary fistula below the buccinator muscle draining into the inferior fornix of the left eye ( Fig. 2 ).
Under general anaesthesia Stensons’s duct was cannulated, the fistula was explored and excised intraorally and the silicon cannula left in situ postoperatively for 1 week. At a follow up examination after 1 week, the epiphora had ceased completely, parotid secretions had commenced intra orally and the wound healed well thereafter.
Parotid fistulae are lesions that occur after trauma or injury in the face causing accumulation and discharge of saliva in the area of disruption. In this patient, the aetiology was trauma but the diagnosis could be made early due to the delay in healing of the infra orbital laceration. The greatest experience with parotid gland injuries was reported by Morestin who described 62 cases of parotid fistula after facial wounds sustained by French soldiers in World War I. They were mainly treated by the surgical creation of an intra oral fistula .
Early diagnosis of parotid fistulae and of the probable site of injury helps to establish the differential diagnosis and aid treatment . Van Sickles and Alexander classified three distinct sites of parotid injury. Site A injuries occur in the glandular tissue posterior to the masseter, site B injuries are those over the masseter, and site C injuries occur anterior to the masseter . Ductal injuries anterior to the parotid are more likely to develop complications. The present patient belonged to this set of patients with duct injury at site C. The accumulation of saliva in the cheek followed by its discharge into the inferior fornix had features of both a sialocele and a fistula.
A large proportion of parotid fistulae may be iatrogenic . They have been reported following superficial parotidectomy, mastiodectomy, mandibular osteotomies and drainage of facial abscesses. A sialocele develops 8–14 days after injury . Unless secondarily infected, there is absence of pain, fever, chills, or erythema of the skin .
Post traumatic sialocele is an acquired lesion that arises from extravasation of saliva into the glandular or periglandular tissues secondary to disruption of the parotid duct or parenchyma . Traumatic causes include sharp penetrating wounds in the oral cavity or in the face and blunt trauma such as zygomatic and mandibular fractures. Extrinsic infections from mandibular teeth, mumps, actinomycosis, tuberculosis and syphilis have been recognized as causes of parotid fistulae .
The diagnosis is complex and involves a combination of thorough history and clinical assessment of the patient, fine needle aspiration and image analysis . When present for more than 2 weeks a capsule may be evident on contrast-enhanced computed tomography . Parotid secretions have a high amylase content that usually exceeds 10,000 units/l; confirming the diagnosis . In the case presented here, the amylase content and the ultrasound scan confirmed the diagnosis and the exit of the fistulous tract to the inferior orbital fornix.
In conclusion, it is unusual to anticipate inferior fornix fistula from the parotid gland. Also the eye being a moist area, fluid drainage at such a site is difficult to observe and diagnose. The case reported here was diagnosed and managed at the earliest opportunity owing to close monitoring and the patient’s observation and cooperation.