What is the most appropriate next step in management for a 79-year-old woman with exposed bone at the site of a third molar, status post chemoradiation therapy, with a PET (Positron Emission Tomography) CT scan showing positive uptake and biopsy revealing only bone and granulation tissue?

Management of Osteoradionecrosis in a Post-Chemoradiation Patient

Hyperbaric oxygen treatment is the most appropriate next step in management for this 79-year-old woman with exposed bone at the third molar site following chemoradiation therapy.

Background and Diagnosis

This patient presents with classic signs of osteoradionecrosis (ORN) of the jaw:

• History of chemoradiation therapy for tonsillar cancer 6 months prior
• Exposed bone at the site of the third molar
• Positive PET-CT uptake at the site
• Biopsy showing only bone and granulation tissue (ruling out tumor recurrence)

Rationale for Hyperbaric Oxygen Therapy

Hyperbaric oxygen (HBO) therapy is specifically indicated in this case for several reasons:

1. The NI-RADS guidelines specifically mention that "hyperbaric oxygen therapy may be provided for patients with radionecrosis" 1. This is particularly relevant when PET imaging shows uptake that could be confused with tumor recurrence.

2. The 2024 ISOO-MASCC-ASCO guidelines for prevention and management of osteoradionecrosis in head and neck cancer patients treated with radiation therapy support the use of HBO for established ORN 1.

3. The positive PET-CT uptake in this case represents post-radiation inflammatory changes rather than tumor recurrence, as confirmed by the biopsy showing only bone and granulation tissue.

Management Algorithm

1. Confirm Diagnosis:

   • Exposed bone after radiation therapy
   • Positive PET-CT uptake
   • Biopsy negative for malignancy (showing only bone and granulation tissue)
   • Consistent with ClinRad classification of ORN 1

2. Initiate HBO Therapy:

   • Typical protocol: 20-40 sessions
   • Daily 90-120 minute sessions
   • Pressure between 2.0 and 2.5 absolute atmospheres 2

3. Concurrent Management:

   • Maintain good oral hygiene
   • Consider conservative debridement only after HBO therapy has improved tissue oxygenation
   • Pain management as needed

Why Other Options Are Not Appropriate

1. Good oral hygiene and follow-up in three months alone:

   • Insufficient for established ORN with exposed bone
   • Delays necessary treatment for a progressive condition

2. Intravenous antibiotics and surgical debridement:

   • Surgical intervention in irradiated tissue without HBO may worsen the condition
   • Poor wound healing in hypoxic irradiated tissue
   • Antibiotics alone won't address the underlying hypovascular, hypocellular, and hypoxic tissue state

3. Wide local excision with bone grafting:

   • Too aggressive as first-line therapy
   • High risk of failure in irradiated tissue without prior HBO
   • May lead to further tissue breakdown and worsen the condition

Monitoring and Follow-up

• Reassess after completion of HBO therapy course
• Evaluate for:
  • Reduction in exposed bone
  • Improvement in tissue vascularity
  • Resolution of PET-CT abnormalities
  • Only consider surgical intervention if no improvement after HBO therapy

Key Considerations

• ORN is characterized by hypovascular, hypocellular, and hypoxic tissue that benefits from HBO's ability to increase tissue oxygenation
• HBO increases tissue oxygen tension several fold, promoting angiogenesis and wound healing 3
• HBO inhibits bacterial growth, particularly anaerobes, which may colonize necrotic bone 4
• The patient's age (79) and post-radiation status make conservative approaches with HBO preferable to immediate aggressive surgery

HBO therapy represents the optimal balance of addressing the underlying pathophysiology while minimizing additional trauma to already compromised tissues in this elderly patient with radiation-induced bone injury.