HIFU burns. Analysis of reported cases of thermal skin damage

Although HIFU is considered a procedure with favorable safety profile, in which most side effects are mild and transient (such as redness, swelling or temporary pain). There are also rare but serious complications, including burns and nerve damage. In order for patients to make an informed decision, a detailed analysis of reported cases of thermal injury is imperative.

1. Causes of thermal damage from HIFU therapy

Burns and thermal damage caused by HIFU are due to uncontrolled or incorrect targeting of thermal energy to the superficial layers of the skin or to critical deep structures.

Key factors contributing to burns:

• Incorrect technique/settings. Incorrect orientation of the device, too high energy or insufficient contact between the tip and the skin.

• Lack of experience/negligence. Inadequate operator expertise or lack of adequate care and precautions.

• Interaction with medications. The use of photosensitive compounds, such as Zoloft, or local remedies such as Tretinoin, can increase the skin's sensitivity to heat and increase the risk of burns and side effects.

2. Reported cases of facial burns

Although HIFU is primarily used for aesthetic purposes, there have been documented cases of serious thermal damage that highlight the need for extreme caution.

2.1. Case with serious facial burns and financial compensation

A case has been documented in Australia where a client of a beauty salon suffered serious facial burns, scars, and disfigurement after HIFU procedure.

• Damages: In addition to serious facial burns, the woman suffered permanent scarring and discoloration (discoloration). The injuries have also caused psychological trauma, major depression, anxiety, and family problems.

• Reason: It was found that HIFU treatment was performed carelessly, with inadequate precautions and lack of reasonable care on the part of the salon.

• Result: The court orders the salon to pay the customer $200,000 in compensation for the permanent injuries and resulting losses. The patient was recommended plastic surgery to correct the defects.

2.2. A case of burn associated with photosensitizing drugs

An online forum describes the case of a 31-year-old woman who received burning cheek during a HIFU procedure, even though the clinic had a good reputation.

• Damage: The burn was visible for weeks. Even after five months, the patient reported permanent scars, even though she had undergone 4 CO₂ laser treatments.

• Missed grade: The patient used Tretinoin and she accepted Zooloft (Zoloft). This is critical because Zoloft is photosensitive compound, which may increase the reaction to heat/light and cause burns.

• Practitioner negligence: The staff he didn't ask for all medications the client is taking, which has been defined by commentators as serious negligence.

2.3. Other reported localized thermal injuries. Mandibular burns and submandibular burns after HIFU.

Mandibular (in the lower jaw area) and submandibular (under the lower jaw) burns are specific examples of thermal skin damage that have been observed in aesthetic HIFU procedures.

Frequency and classification of complications

A systematic review of the efficacy of MFU for facial skin tightening indicated that other adverse effects, besides transient redness and swelling, were rare. "Rare, but potentially significant, complications include dysesthesia (tingling or hypersensitivity), bruising, stinging, mandibular burns, stretch marks and contact dermatitis." (publication: International Journal of Environmental Research and Public Health 2023, 20, 1522.,).

Reported cases

In one study from the above-cited systematic review by Lu et al., evaluating MFU on the face and neck (total 25 patients – 92% women), cases of submandibular burns.

The following cases are listed in a table describing adverse events:

• Three cases on painful sensation/discomfort (soreness).

• 20 cases on bruising/swelling/erythema (bruising/edema/erythema).

• Two other cases: contact dermatitis and submandibular burns.

Conclusion:

Erythema (redness) and the swelling (swelling) are very common and occurred in a large proportion of patients in this study (20 cases). Other, less common and significant side effects (such as submandibular burn and contact dermatitis) occurred at two the patient.

The risk of thermal damage in the lower jaw area and below is increased due to anatomical and technical factors:

• Proximity to bony structures. Bony prominences, including the lower edge of the mandible (jawbone), are prohibited treatment areas.

• Mechanism of damage. Ultrasonic energy can be absorbed or reflected from the bone surface, when the soft tissue layer (fat and muscle) is thin. This increased absorption and reflection of energy near the bone can lead to severe discomfort and potential thermal stress on the skin and underlying tissues.

• Incorrect technique. Burns may occur if the HIFU device is misdirected or broadcasts too much energy to the skin, causing overheating. Incorrect settings, inadequate operator expertise, and insufficient contact between the applicator and the skin can also contribute to complications.

General preventive measures

To prevent local burns, including mandibular and submandibular, clinical consensus recommends:

1. Avoiding bony edges. Avoid direct treatment with the bone edges.
2. Nozzle pressure. When using a 4.5 mm tip, a just a little pressure, so that the treatment surface is level with the skin. Excessive pressure should be avoided, especially in weaker clients with thin subcutaneous tissue.
3. Immediate termination. If they appear papules, blisters, or linear skin elevations (which are signs of thermal damage), treatment should be immediately terminated and apply local cold compresses.

3. Deep thermal damage in therapeutic HIFU

Thermal damage is not limited to the surface. Procedures performed in deeper areas (e.g. gynecological or abdominal) also carry the risk of thermal necrosis of structures passing through the path of the ultrasound waves.

Case with necrosis of the abdominal wall and uterus

It is described severe case, in which HIFU ablation aimed at treating uterine adenomyosis, has caused acute and severe thermal injury of the surrounding tissues.

• Damages: The patient was admitted to the emergency department with abdominal pain and fever. A CT scan confirmed thermal damage with necrosis of the skin, subcutaneous tissue, muscles of the anterior abdominal wall, peritoneum and uterus.

• Intervention: It has become necessary. emergency surgery, including total abdominal hysterectomy (removal of the uterus) and removal of necrotic muscles and skin.

• Reasons: The damage is caused by the high-energy ultrasound waves passing through the focal zone, which can induce damage to internal organs or underlying soft tissues. Causes may include: inaccurate targets, excessive energy generation or unqualified operator.

To minimize the risk, patients should:

1. To choose qualified specialists. The procedure should only be performed by trained medical professionals, familiar with the anatomical risks and specific work parameters.

2. Disclose their full medical history. It is mandatory to report all medications taken (including Tretinoin and antidepressants such as Zooloft) as photosensitive compounds can dramatically increase the risk of thermal reactions.

3. Be informed about prohibited areas. It is important to avoid treatment in areas with thin skin, as well as areas close to bones, large nerves, or critical structures (such as thyroid gland), where the risk of injury is increased.