Introduction

The acute patient with pharyngeal stick penetration injury (PSPI) presents with pain, dysphagia, and hypersalivation with sometimes blood in the saliva. Some patients may show emphysema in the cervical area or are reluctant to move the head. Pharyngeal swelling and pneumomediastinum may become life-threatening. Chronic PSPI patients with injuries that happened more than 7 days prior to admission present with less severe signs. In the majority of chronic cases recurrent abscessation in the neck area is observed. Migrating wooden fragments cause persisting discharging sinuses that release purulent or serosanguinous fluid.^1-3 Retrospective studies proved that most acute cases of PSPI can be managed successfully, while some chronic cases may be very difficult to cure. Cases with perforations of the esophagus have a worse prognosis, compared to cases with oropharyngeal lacerations.^1,2

Acute PSPI

The management of a patient with acute PSPI is directed at stabilization of the patient, repair of the oropharyngeal or esophageal perforation, the retrieval of foreign bodies, and the drainage of the penetration tract.

All patients are examined using a general emergency protocol, for instance the A (airway), B (breathing), C (circulation) protocol. Dyspnea might develop as a result of pharyngeal swelling or mediastinal emphysema. An oxygen mask is used to improve the patients' saturation before further diagnostic examinations are performed. Intravenous fluids and broad-spectrum antibiotics are indicated in all cases. Attention is paid to neurological symptoms related to cervical trauma, such as paresis or Horner's syndrome.⁴ In most cases of pharyngeal, esophageal, or laryngo-tracheal lacerations subcutaneous and mediastinal emphysema is visible on plain radiographs of the neck and thoracic cavity. Pneumomediastinum and pneumothorax are indicators for deep penetrating injuries. The clinical situation in these patients may worsen during examination procedures! Thoracocentesis equipment as well as endotracheal tubes should be at hand at all times. It is important to realize that wood does not show on radiographs! Radiographs are made to identify the extension of subcutaneous and mediastinal emphysema, and not to localize wooden foreign bodies. In the acute PSPI patient ultrasound of the throat and neck is not of great use: subcutaneous emphysema will mask small foreign bodies. Large foreign bodies will be recognized during surgery. After completing the general emergency protocol, all acute PSPI patients are anesthetized for a thorough inspection of the oropharyngeal cavity. Intravenous propofol may be used for the induction of anesthesia; atropine is added in patients with bradycardia. Methadone is added as a strong analgesic and has a good effect in these patients.

Oropharyngeal inspection is performed with the patient in sternal recumbency. The following areas and structures are visualized before endotracheal intubation: the sublingual areas left and right to the frenulum; the tongue (base, left and right); the lateral pharyngeal walls and tonsillar crypts on both sides; the hard and soft palate; with the help of a laryngoscope the epiglottis is visualized with its attachments to the pharynx and the larynx. After the inspection of the glottis (including vocal cords and laryngeal cartilages), the patient is intubated with an endotracheal tube of the correct size. With the endotracheal tube in place, the larynx is depressed ventrally with the help of a laryngoscope and the pharynx is inspected completely. The caudal pharynx is inspected after rostral retraction of the soft palate. Retrograde nasopharyngoscopy with a flexible endoscope is indicated in cases with perforations of the soft or hard palate. The rostral esophagus is inspected after ventral depression of the intubated larynx with a long-bladed laryngoscope or by using an endoscope. When perforations are not found at this time, complete cervical esophageal endoscopy is advised. When wood fragments are recognized within the soft tissues of a penetration tract retrograde withdrawal is not recommended because of the risk of fragmentation. In all cases of perforations of the pharyngeal or esophageal wall surgical exploration of the neck through a ventral midline approach is recommended. Incisions begin at the level of the hyoid cartilages and extend towards the thoracic inlet. In cases with sublingual perforations the incision is extended into the inter-mandibular area.

Surgical Procedure

The patient is positioned in dorsal recumbency with a small neck support. The front legs are retracted caudally. A ventral midline skin incision is used and the ventral musculature of the neck is exposed. The penetration tract is estimated by using the localization of the laceration relative to the surrounding boney (jaw, skull, vertebrae) and cartilaginous (larynx, trachea) structures, and the direction of the penetration tract as landmarks. To identify the penetration tract a sterile probe or urinary catheter may be inserted into the oropharyngeal laceration by an assistant. Using digital palpation of the neck, the surgeon identifies the probe and therefore also the penetration tract. The area of the penetration tract is explored by careful dissection around the muscular, nervous, and vessel structures, starting in the lower neck near the thoracic inlet, and working form unaffected (clean) towards affected (dirty) tissues in rostral direction. The areas rostral to the cricoid cartilage should be dissected with great care. The surgeon should be aware of the anatomy of the laryngeal and pharyngeal nervous innervations. The penetration tract is exposed and remaining foreign bodies are removed. The tract is gently flushed with saline. Wounds are closed over a Penrose® drain with only one point of exit per drain, in the lower neck area. In cases of esophageal trauma the same surgical approach is used. Stay sutures are placed in the esophageal wall around the perforation. Sometimes rotation of the larynx and trachea will help to expose the lacerated esophagus. After debridement of the laceration, the esophagus is sutured with PDS (polydioxanone 3-0 or 4-0) in a perforating interrupted pattern. Sutures are all pre-placed before tying. A muscular patch is used to improve esophageal wound healing. In cases with severe esophageal lesions a gastrostomy feeding tube is indicated to by-pass the sutured esophagus.

After completing the surgical procedure in the neck, dorsal and dorsolateral pharyngeal perforations and lacerations in the soft palate are sutured with absorbable suture material via an oral approach. Long surgical instruments are of great help. Small sublingual perforations may be left unsutured.

Chronic PSPI

Cases with chronic PSPI present with a recurrent swelling or abscess in the soft tissues of the head or neck, with sometimes a cutaneous draining sinus. The original injury may have occurred unnoticed or the acute PSPI was managed unsuccessfully. The management of chronic PSPI is directed at residual foreign body retrieval and drainage of the infected area. The principles of the inspection of the oropharyngeal cavity and the proximal esophagus, the surgical techniques and the drainage of the infected areas, are the same as in the acutely injured patients. The perforation site is recognized when its scar is found. In the ideal situation, the number and localization of the remaining foreign bodies is determined before surgery. Unfortunately it is impossible to demonstrate the absence of residual stick fragments. Plain and contrast radiography (sinography), ultrasonography, CT, and MRI have all been described for the detection of foreign bodies in chronic PSPI.^3,5,6 The choice of the diagnostic technique depends on availability, costs, and whether extra anesthesia time (CT and MRI) is not harmful to the patient. Sinography is only applicable in cases with external draining sinuses and will visualize foreign bodies in only a few cases because of the diffusion of contrast material in the loose subcutaneous tissues. Ultrasonography is cheap, anesthesia is not needed in most cases, and foreign bodies are easily recognized when surrounded by inflammatory exudates. Computer tomography with or without IV contrast has been proven to be accurate in recognizing wooden foreign bodies. Depending on the water content of the different layers of the sticks, the foreign bodies show a variable attenuation pattern. CT images and three-dimensional reconstructions may aid in the planning of surgery in difficult cases.⁶ The use of MRI in dogs with chronic PSPI has been evaluated in small series of cases and was helpful in the localization of wooden foreign bodies. Other types of plant material (grass awns) were less apparent on MRI images.⁵

Penrose® drains are used in all cases of surgical exploration in chronic PSPI patients. The prognosis is excellent for cases where remaining foreign bodies can be retrieved.^1,2

References

1.  White RAS, Lane JG. Pharyngeal stick penetration injuries in the dog. J Small Anim Pract 1988;29:13–35.

2.  Griffiths LG, Tiruneh R, Sullivan M, et al. Oropharyngeal penetrating injuries in 50 dogs: a retrospective study. Vet Surg 2000;29:383–388.

3.  Doran IP, Wright CA, Moore AH. Acute oropharyngeal and esophageal stick injury in forty-one dogs. Vet Surg 2008;37:781–785.

4.  Rayward RM. Acute onset of quadriparesis as a sequela to an oropharyngeal stick injury. J Small Anim Pract 2002;43:295–298.

5.  Dobromylskyj MJ, Dennis R, Ladlow JF, et al. The use of magnetic resonance imaging in the management of pharyngeal penetration injuries in dogs. J Small Anim Pract 2008;49:74–79.

6.  Nicholson I, Halfacree Z, Whatmough C, et al. Computed tomography as an aid to management of chronic oropharyngeal stick injury in the dog. J Small Anim Pract 2008;49:451–457.