NECK TISSUE NECROSIS:
DELAYED RADIATION TREATMENT DAMAGE

    NECK

    Acute radiation complications, usually cellular and mucosal, result from cellular DNA damage and cell death. Generally, these acute complications are predictable and not dose limiting. Many oncologists and pathologists originally believed late radiation damage, vascular and stromal, was unrelated to acute damage. Today, further understanding suggests that the more-dreaded and dose-limiting late radiation damage actually begins at the onset of radiation therapy, although it may take months to years after radiation before symptoms appear. This late radiation injury, the fibrosis and endarteritis which restricts tissue blood flow and oxygenation, can result in tissue death.

    Elevation of fibrogenetic cytokines and other biochemical markers or the depression of protective cytokines at treatment are both associated with late radiation damage. Reliable predictive assays to identify those at risk for late radiation damage and the development of effective treatment strategies for that latent period between radiation treatment and symptom onset are essential to prevent and/or reverse these complications. Hyperbaric oxygen therapy is a successful therapeutic modality for this latent period, and even after the expression of delayed radiation injury.

    A study by Feldmeier and Hampson found positive results for hyperbaric treatment in 67 of 74 publications. HBO therapy induced neovascularization, increasing tissue oxygenation, and reduced irradiated tissue necrosis.

    Donovan, Huynh, Purdom, Johnson, and Sniezek reported the difficulties for patients who suffer damage to the cervical spine following radiation treatment of the head and neck. Two of three patients studied had osteomyelitis (bone inflammation) which required surgery to reconstruct the spine, followed by HBOT. The spine was stabilized, and neurological function resolved. In a third, less severe case, HBOT was used alone, with improved symptoms and imaging.

LARYNGEAL NECROSIS

    Radiation-induced laryngeal necrosis is not a common complication, occurring less than 1% of the time in a well-designed radiation treatment program. Higher treatment-fraction doses, higher total doses, and the use of neutron irradiation increase its incidence. When subsequent tissue swelling persists, laryngectomy (removal of the voice box) has often been the only choice. This has been selected for two reasons: 1) persistent swelling suggested the presence of cancerous tissue; and 2) an effective way to reverse chondronecrosis (the death of the cartilaginous tissues of the larynx) was not known. The result of either of these conditions can be swelling, constriction of the airway, foul breath, and the continued production of dead tissue.

    Biopsy is often inaccurate and may further aggravate the necrotic process, although it may be required to rule out tumor recurrence. Studies have shown that laryngectomy may not be required to resolve this problem. In three trials, only six of thirty-five patients treated with hyperbaric oxygen required laryngectomy—the remainder maintained their voice box, often with good voice quality.

     OTHER NECK SOFT-TISSUE NECROSIS

    In Hyperbaric Medicine Practice, Marx reported his experience using hyperbaric oxygen in a controlled, but not randomized treatment of head and neck soft-tissue radionecrosis. In this instance, some patients lived too far away, could not afford, or refused hyperbaric treatment. Except for HBOT, all other aspects of treatment for the two heavily irradiated surgical resection or flap reconstruction groups was identical.

Group	Treatment	Wound infection	Wound dehiscence (rupture)	Delayed wound healing
HBOT (160 patients)	20 pre-operative HBOT treatments at 2.4 ATA followed by 10 post-operative HBOT treatments	6%	11%	11%
No HBOT	None	24%	48%	55%

    A case series by Davis using HBOT for resolution of the necrosis reported success in fifteen of sixteen patients. A 1997 study by Neovius reported that twelve of fifteen experienced total healing, two improved, and one had no benefit from hyperbaric oxygen treatment. In the control group, only seven healed completely and two hemorrhaged, one of those bleeding to death as a result of the wound eroding into a major blood vessel.

    Clearly, HBOT is worth considering to resolve head and neck soft-tissue necrosis.

When the larynx (voice box) or neck have been treated with radiation, HBOT can result in significant or total resolution of pain, swelling, and tissue death and often enables speech.