Sublingual Space Infection

Sublingual space infection is infection in the floor of the mouth superior to the mylohyoid muscle and lateral to the genioglossus. It is the smaller of the paired spaces that, together with the submandibular and submental spaces, make up Ludwig angina when all become involved.

It arises from lower anterior teeth and premolars whose root apices lie superior to the mylohyoid line, and from lower molars with long roots in some people. Submandibular gland and duct disease, floor of mouth trauma and piercings are other causes.

Pathophysiology. Infection exits through the lingual cortex superior to the mylohyoid and enters the sublingual space, which communicates freely with the submandibular space around the posterior free edge of the mylohyoid.

The space contains the sublingual gland, Wharton duct, lingual nerve, hypoglossal nerve and lingual vessels. Swelling displaces the tongue upward and backward, narrowing the airway.

Pain and swelling in the floor of the mouth, a raised tongue, difficulty swallowing and speaking, drooling, reduced tongue movement, sublingual redness and tenderness, and sometimes salivary stasis with a bad taste. Trismus is usually mild. Fever and tachycardia are frequent.

Bilateral swelling, a woody neck swelling under the chin, protruding or elevated tongue, voice change, inability to swallow saliva and stridor indicate impending airway obstruction and need an emergency airway team.

• Airway assessment before any other step.
• Intraoral examination: elevated floor of mouth, pus at the opening of Wharton duct, source tooth, and bimanual palpation for a salivary stone.
• Contrast CT of the face and neck: collection, gas, airway narrowing, spread to submandibular and parapharyngeal spaces, and ductal stone.
• Bloods: full blood count, C-reactive protein, glucose, urea and electrolytes, blood cultures when febrile.
• Culture of pus.
• Ultrasound when a salivary stone or superficial collection is suspected.

Differential diagnosis.

• Submandibular space infection and Ludwig angina
• Submandibular sialolithiasis with sialadenitis
• Ranula and plunging ranula
• Angioedema of the tongue or floor of mouth
• Floor of mouth carcinoma
• Cellulitis from piercing or trauma
• Dermoid cyst

• Secure the airway with an experienced anaesthetist, with awake fibreoptic intubation or tracheostomy in impending obstruction, and keep the patient upright.
• Antibiotics: benzylpenicillin 1.2 g intravenously every 6 hours (or amoxicillin 1 g intravenously every 8 hours) with metronidazole 500 mg intravenously every 8 hours. Penicillin allergy: clindamycin 600 mg intravenously every 6 to 8 hours (maximum 2.4 g daily). Convert to oral amoxicillin 500 mg to 1 g three times daily with metronidazole 400 mg three times daily after improvement, completing 7 to 10 days. Reduce amoxicillin when eGFR is under 30.
• Remove the source tooth, and drain any collection through an intraoral incision in the floor of the mouth, parallel to Wharton duct and lateral to the sublingual fold, with blunt dissection to avoid the duct, lingual nerve and lingual vessels.
• Surgery by the extraoral approach is needed when infection extends into the submandibular and submental spaces.
• Remove a salivary stone from the duct and give antibiotics for sialadenitis, with sialendoscopy or excision of the gland in recurrent disease.
• Analgesia: paracetamol 1 g every 6 hours (maximum 4 g daily) with ibuprofen 400 mg every 8 hours with food, avoided in renal impairment.
• Hydration and nutrition, with a nasogastric tube if swallowing is impaired.

Monitoring. Hourly airway and oxygen saturation checks in the early phase, temperature, tongue position and swelling, and C-reactive protein daily. Repeat CT if there is no improvement in 48 to 72 hours.

Referral and escalation. Refer urgently to oral and maxillofacial surgery or ENT with critical care. Emergency escalation for any airway symptoms, bilateral swelling or sepsis.