Back in the 1920s, when liposuction was first developed by Charles Dujarier, gangrene and necrosis set in to cause the death of his patient when he attempted to remove fat from the calves. Nowadays, patients are able to obtain predictable and safe results with liposuction. However, as with many aesthetic techniques and procedures, the trend with cosmetic procedures has been a shift to treatment modalities that are minimally invasive and can still able achieve excellent results. Currently, there are several of these non-invasive modalities that are being employed in the market, namely injection lipolysis, high-intensity focused ultrasound, non-thermal focused ultrasound, cryolipolysis, radiofrequency, and low-level light therapy. Injection lipolysis have been in use for a longer period of time compared to the other aforementioned methods. In the United States alone, statistics suggest that minimally invasive procedures have grown in popularity by 137% from the year 2000 to 2012.
This development is understandable: they can afford a type of convenience that many surgical procedures cannot even come close to approaching. Earning themselves the nickname “lunch-time procedures,” these procedures are able to be done in a few short hours and can have little no risks of serious adverse effects and generally do not require significant downtime. This is excellent news for many patients with a fast-paced modern life, which can be time-restrictive. Moreover, the cost of minimally invasive procedures are significantly less than surgical procedures, but this may be offset by the multiple treatment sessions needed. Additionally, with these minimally invasive procedures, the need for general anesthesia and the risks of infection and permanent scarring occurring are minimal, all of which greatly enhances the safety profile of these procedures. This article is written to guide medical professionals on the various treatment options available for non-surgical body contouring and to inform you about certain endocrine physiology.
A few types of modalities to discuss
Low-level light therapy (LLLT) has been cleared by the FDA for fat reduction around the waist. High-intensity focused ultrasound causes thermal damage to destroy adipocytes. Radiofrequency operates on a similar principle with thermal damage caused by an oscillating electrical field, but it can penetrate more deeply into the tissues. In contrast, cryolipolysis, as its name suggests, induces adipocyte apoptosis through the freezing of tissues and the subsequent thermal energy extraction that occurs without causing any damage to the surface epidermis. On a related note, a 2015 study found that cryolipolysis and ultrasound cavitation are effective body contouring treatments with a strong safety profile. Both had similar efficacies in terms of their ability to reduce subcutaneous fat at the abdominal region to reduce waist circumference and skinfold.
How do they work?
These minimally-invasive methods all function similarly, as they all, in one way or another, induce adipocyte apoptosis so that subcutaneous fat can be decreased. This may be surprising to some, but the effects of these treatment modalities will have no bearing on the patient’s lipid profile or liver function test. As the adipocytes are affected, the triglyceride components enter the interstitial tissues and are transported to the vascular lymphatic system and eventually reach the liver. In turn, they are metabolized into glycerol and free unsaturated fats via enzymes called endogenous lipases. Triglycerides that escape the metabolism are merged with transporter proteins or lipoprotein complexes to join the lipoprotein pool.
Cryolipolysis is usually performed via the Zeltiq Breeze system as part of a CoolSculpting treatment. Cryolipolysis has undergone both porcine and human trials that have shown considerable reductions in subcutaneous fat. The underlying principle at the core of cryolipolysis’s mechanism of action is based on the fact that lipids crystallize at temperatures that far exceed the freezing point of tissue water. Upon being frozen, lipid-rich cells, such as adipocytes, undergo significant stress that ultimately results in cell apoptosis. Using the system to induce deep cooling, cold panniculitis, a type of inflammatory reaction, occurs and causes the selective loss of subcutaneous fat tissues. In non-lipid storing cells, however, the lipids are left undamaged.
Ultrasound-assisted liposuction has existed since the late 1980s but only entered the United States in 1993. The third-generation VASER system is the most commonly used system for this treatment modality. Ultrasounds operate on three mechanisms: thermal, mechanical, and cavitation. The thermal and mechanical processes are produced by rapid vibrations from the probe, while cavitation is due to the dispersion of a wetting solution, specifically 1ml of epinephrine mixed with a 1L bag of Ringer's lactate, that causes microbubbles to form in the fat tissues. The microbubbles implode and collapse with the introduction of the ultrasound system, and this, in turn, results in adipocyte separation. When they are mixed with a tumescent solution by acoustic streaming, an emulsion is created. The emulsion is then aspirated via a suction cannula.
Radiofrequency devices act via thermal injury based on both the local current density and the electrical impedance of the tissue. The widespread use of these devices is based on data that demonstrated that 60% of adipocytes in the treated area will be eliminated through heating them at 45ºC with radiofrequency energy. They were originally used to tighten skin and reduce the appearance of wrinkles, as the heat energy could induce collagen contraction and remodeling. Limitations, however, include patient discomfort with skin heating and lack of consistency and uniformity in radiofrequency’s effects on the skin.
Low-level laser therapy (LLLT) refers to inducing a dose rate that causes no immediate rise in temperature and no gross changes in the structure of the tissue. LLLT’s mechanism of action depends on its ability to create temporary pores in adipocytes that causes lipids to be released and removed from the lymphatic system. The first FDA approved LLLT is the Zerona laser, which was designed for bringing about fat reduction in the waist, hips, and thighs.
Low-level light laser therapy
Over the past five decades, lasers and light-emitting diodes were used for medical biostimulation purposes outside the United States. Though there is no strong evidence supporting their use, still there have been numerous reports that purported to show their influence in metabolism modulation in mammals. LLLT was first used in 1970 by Endre Mester to regrow hair in mice with a helium-neon 694nm ruby laser. He later attempted to stimulate wound repair via a 632.8nm laser. The potential for this technology is increasingly being studied. LLLT has been shown to induce a variety of physiological changes; they are capable of causing different gene expression(s), influencing cell proliferation, affecting the intracellular pH balance, altering mitochondrial membrane potential, forming reactive oxygen species, and changing calcium ion levels amongst other known functions. Many practitioners have ceased using LLLT. Instead, osteopaths and chiropractors are the main users of LLLTs. However, with further advancements in research, LLLT may soon have a new purpose in the field of minimally invasive procedures for body contouring.
How does LLLT work?
The methodology behind LLLT is based on the theory of the first law of photochemistry and the absorption of red and near infrared light. LLLT is only functional if there is a photoreceptor molecule that receives the photonic energy. The procedure does not induce thermal damage, so the patient will not feel any heat-related discomfort. In the case of LLLT, cytochrome c oxidase and the terminal respiratory chain enzyme are the photoreceptors. Cytochrome c oxidase is a membrane protein that alters the mitochondrial membrane potential when it absorbs photonic energy from 633nm lasers. As the proton gradient rises, the mitochondria changes, which induces a higher rate ofelectrons being transported by cytochrome c oxidase from cytochrome c to dioxygen. This is the current explanation for higher lipid peroxidation, which breaks down membrane integrity through its oxidative degeneration of the cholesterol found in membranes. Increased production of reactive oxygen species alters the cellular redox state and gene expression through stimulating certain cell signaling pathways. Adenosine triphosphate (ATP) production is increased along with bioenergetics that stimulates the secondary messenger system to change cellular activity. Furthermore, the redox state is modified into an oxidative state, and the redox sensitive transcription factors are initiated by nuclear factor kappa B and activator protein-1. These transcription factors are known to play an important role in changing the permeability of fat cells. It is still uncertain, however, if the pores are induced by gene upregulation, lipid peroxidation, or an exocytosis-like event.
What is the evidence for LLLT?
Studies examined LLLT by using red diodes at 635nm and green diodes at 532nm for 40 minutes and 30 minutes, respectively, three time per week for two weeks. One study concerning the red diode found 4.5 inches of circumference reduction at the waist, thigh, hip, and upper abdomen when used once a week for 40 minutes. Another study evaluating 67 patients found that the average reduction was 3.51 inches in two weeks. On the other hand, the treatment with the green diode showed a 3.9-inch reduction in two weeks. A randomized study looking at the endocrine effects of LLLT showed that it has a role in regulating leptin gene expression, particularly the Ob (Lep) gene. Leptin is produced by adipocytes and functions to influence the appetite by acting on the hypothalamus, which reduces the hunger sensation. However, when adipocytes enlarge, the subsequent increase in leptin production causes the receptors in the hypothalamus to be resistant. Other functions of leptin include affecting energy expenditure and neuroendocrine function. In a non-controlled, non-randomized study of 22 patients aged 18 to 65 years old that were treated with Zerona for two weeks three times per week, Leptin was found to be reduced by about 50% from a starting point of 29.49 to 14.60, p=<0.0001.
Summary
The strong interest in safer and less invasive body contouring procedures will no doubt drive the aesthetic industry onward to more effective procedures and modalities that minimize downtime and recovery while providing better results. The future will likely categorize patients based on their requirements, including categories of patients needing aggressive surgical intervention, minimally invasive liposuction, or even non-invasive techniques. The future of these procedures can only be promising if they are proven to be safe and efficacious. Further research into these different treatment modalities is needed before any serious adoption of these techniques into everyday practice occurs. Currently, the ideal patients that are suitable for these procedures are those that can accept mild to moderate results. Due to this, patient selection must be judicious, and these treatment modalities should not be promoted to patients without informing them of the nature and realities of said treatment modalities. However, incorporating these procedures into the field will ultimately yield more benefit, as it provides another method in which to approach patients and their body contouring needs. Patients that want to opt for less invasive procedures clearly have choices that can lead to improved satisfaction.