Frontal Sinusitis

Frontal sinusitis is inflammation of the frontal sinus, usually with obstruction of the frontal recess. It causes forehead pain, and carries a high risk of orbital and intracranial complications, particularly in adolescents and young men.

It is most common in teenagers and adults over 20 years, when the frontal sinus has developed, and is rare under age 5. Common organisms are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and anaerobes. Complications include subperiosteal abscess, osteomyelitis (Pott puffy tumour), epidural and subdural empyema, meningitis and brain abscess.

Pathophysiology.

Obstruction of the narrow frontal recess traps mucus and bacteria. The posterior wall and diploic veins allow spread of infection to the dura and frontal bone.

Frontal headache, worse on bending forwards, tenderness over the sinus, nasal blockage, purulent discharge, fever and periorbital swelling. Forehead swelling indicates a subperiosteal abscess.

Red flags.

• Forehead swelling (Pott puffy tumour).
• Orbital swelling, proptosis or reduced vision.
• Severe headache, fever, vomiting or neck stiffness.
• Seizures or focal deficits.

Nasal endoscopy shows pus in the frontal recess. CT of the sinuses with contrast defines the frontal sinus and complications (bone erosion, subperiosteal abscess, orbital extension). Magnetic resonance imaging is done for intracranial complications. Send blood cultures, full blood count and C-reactive protein, and swab culture.

Differential diagnosis.

• Acute viral rhinosinusitis.
• Migraine, cluster and tension headache.
• Frontal mucocele.
• Fungal sinusitis.
• Sinonasal tumour.
• Herpes zoster of the forehead.

Uncomplicated acute frontal sinusitis is treated with analgesia, decongestant, topical steroid and antibiotics. Complicated disease needs intravenous antibiotics and urgent drainage (endoscopic frontal sinusotomy, or trephine for abscess).

• Co-amoxiclav (uncomplicated): 625 mg orally three times daily for 10 to 14 days; maximum 1.5 g amoxicillin daily; monitor liver tests, diarrhoea and rash; give 625 mg twice daily when creatinine clearance is 10 to 30 mL/min; children 25 mg/kg amoxicillin twice daily.
• Ceftriaxone (complicated): 2 g IV every 12 hours; maximum 4 g daily; 2 to 6 weeks depending on complications; monitor renal function, liver tests and blood counts; no routine renal adjustment.
• Metronidazole (with ceftriaxone): 500 mg IV or orally every 8 hours; maximum 1.5 g daily; monitor neuropathy and liver tests; reduce to 500 mg every 12 hours in severe hepatic impairment.
• Oxymetazoline 0.05% nasal spray: 2 sprays into each nostril every 12 hours for up to 3 days; maximum 3 days of use; monitor blood pressure; avoid in uncontrolled hypertension.
• Mometasone nasal spray 50 micrograms for each spray: 2 sprays into each nostril twice daily for 2 weeks; maximum 400 micrograms daily in each nostril.

Monitoring. Review at 48 to 72 hours; neurological and eye examination every 4 to 6 hours in complicated disease.

Referral and escalation. ENT urgently; neurosurgery and ophthalmology for complications.

Special groups. Children need weight based dosing and early imaging for eye signs.