- •
Cryolipolysis is a novel approach to noninvasive subcutaneous fat reduction
- •
It is both safe and effective with essentially no post-procedure downtime
- •
Commonly treated areas include flanks, upper and lower abdomen, and back fat pads
- •
The pre-procedure consultation is critical to selecting appropriate patients for this treatment
- •
Erythema, mild edema and petechiae are common immediate sequelae that typically resolve within a week
- •
A transient reduction in sensation (i.e. paresthesia) may also be experienced but this typically resolves within a few weeks
- •
No significant negative long-term sequelae have been observed to date
Introduction
As body contouring and selective fat removal have become a frequent goal of aesthetically-oriented procedures, there have been numerous efforts to develop a technique that is effective yet noninvasive and leads to minimal or no patient downtime. For decades, liposuction has been a gold standard procedure in fat removal. Although this treatment is highly effective for high volume localized fat removal, it requires small incisions in the skin followed by various modalities to loosen the adipose tissue prior to suctioning excess fat through a cannula. Due to the moderately invasive nature of liposuction, it can uncommonly lead to complications including hematomas, infection, scarring, sensation changes, nonuniform fat reduction, and damage to underlying structures. Because of the potential side effects and social downtime associated with liposuction and surgical approaches to fat reduction, there have been recent and ongoing efforts to develop truly noninvasive techniques to selectively decrease adipose tissue. Evolving methods developed to date include ultrasound, radiofrequency, infrared light and laser treatments, all of which have been associated with variable results and sometimes limited efficacy. A recent alternative approach has been founded on the concept of selective cryolipolysis. Cryolipolysis literally means ‘freezing of fat’ and this treatment modality utilizes targeted cold exposure to produce selective fat reduction without damaging overlying skin or surrounding tissue. As this treatment is completely noninvasive, there is no post-procedure downtime and little risk for significant long-term side effects or complications.
Pathophysiology/mechanism of action
Initial hints that fat cells are preferentially sensitive to cold exposure included two clinical entities – the well-known ‘popsicle panniculitis’ and the so-called ‘equestrian panniculitis’. Popsicle panniculitis was initially described as early as the 1960s when it was noted that children who sucked on frozen treats for extended periods of time developed inflammation and subsequent loss of buccal fat tissue. Similar findings of inflammation and fat loss were later noted in female equestrian riders who wore tight pants in cold climates. This latter clinical scenario was therefore termed ‘equestrian panniculitis’. Together, these findings ultimately provoked various animal and clinical studies designed to explore the link between cold exposure and selective fat destruction.
The initial animal studies were performed by Manstein and colleagues and consisted of three complementary experiments involving Yucatan pigs. The first of the series was considered an exploratory study designed to determine the feasibility of noninvasive, cold induced, selective destruction of subcutaneous fat. In this initial project, a black Yucatan pig was subjected to a slightly convex circular copper plate that was pressed firmly against the skin surface and was cooled by antifreeze solution set at −7 °C. The cold exposure time varied between 5 and 21 minutes and was repeated at several different locations. Following cold exposure, the pig was monitored for 3.5 months and researchers observed the appearance and persistence of localized fat loss. During this time, it was noted that the pig developed focal indentations at the sites of contact with the cooling device. As compared with adjacent untreated areas, histologic sections of the treated sites demonstrated an estimated 80% loss of the superficial layer of adipose tissue for a total loss of 40% of the measured thickness of the subcutaneous tissue. There was also a marked reduction in the distance between fat septa with no evidence of surrounding skin injury and only transient hyperpigmentation in the overlying skin.
In a subsequent dosimetry study, four pigs were treated with a prototype device (Zeltiq Aesthetics Inc., Pleasanton, CA) containing a thermoelectric cooling element. The animals studied were treated with either a flat device applicator pressed firmly against the skin or with the treated skin folds captured between two cooling plates. The cooling plates were kept at a pre-set temperature ranging from −1 °C to −7 °C for 10 minutes. Animals were sacrificed at selected time points ranging from immediately to 28 days post-procedure. Test sites and surrounding areas were assessed clinically, with an ultrasound device, and with histologic sections. Findings included clinically obvious indentations at various test sites where the cooling plate applicator was used. However, there was no apparent clinical change at locations where the flat applicator was used. Using an ultrasound device, treated areas were assessed at 30 days post-treatment and an approximately 3 mm thickness of fat loss was demonstrated as compared with surrounding untreated skin. Furthermore and perhaps most importantly, the histologic findings supported the theory that cold exposure may induce selective fat loss without damage to surrounding tissues. As seen in Table 6.1 , histologic sections immediately following the procedure demonstrated normally shaped adipocytes and no inflammatory cells. By day 2 after cold exposure, adipocytes again appeared normal, but there was evidence of localized inflammation in the subcutaneous tissue. Specifically, the inflammation consisted of clusters of neutrophils and monocytes in a lobular pattern. By day 14 following treatment, there was evidence of a reduction in adipocyte size as well as a heavier inflammatory infiltrate consisting of occasional macrophages. And finally, by day 30, there was an even greater reduction in adipocyte size and an increased density of macrophages, suggesting more significant phagocytosis of the damaged adipocytes. Importantly, blinded grading of the degree of inflammation suggested relatively greater adipocyte damage and a heavier inflammatory infiltrate at lower temperatures.
Selective cooling of superficial fat leads to apoptosis of adipocytes followed by gradual clearing of the apoptotic debris by inflammatory cells. As this is a selective process, the overlying epidermis and dermis are generally unaffected and surrounding, untreated skin is left uninjured.
| Day post-treatment | Histological findings |
|---|---|
| Day 0 | Within first hour, normally shaped and sized adipocytes with no inflammatory cells |
| Day 2 | Clusters of inflammatory cells (mainly neutrophils) surrounding individual adipocytes |
| Day 14 | Dense lymphocytic infiltrate with occasional macrophages and some reduction of adipocyte size |
| Day 30 | Dense lymphocytic infiltrate, multinucleated giant cells (macrophages), further reduction of adipocyte size |
Although the exact mechanism(s) of action remain somewhat unclear, the pre-clinical studies noted above confirmed the phenomenon of selective cryolipolysis with regulated cold exposure leading to apoptosis of adipocytes. These findings ultimately led to the development of the Zeltiq system (Zeltiq, Pleasanton, CA) which is the first device developed for human use. This system consists of a control unit with a cup-shaped applicator that uses vacuum suction to position the excess adipose tissue between two cooling plates. The cooling of the plates is modulated by a thermoelectric cooling element which extracts energy from the underlying adipose tissue without damaging the overlying skin. The temperature is controlled and kept constant by sensors embedded in the cooling plate. Further, the device’s applicators are designed to apply sufficient pressure to nearly eliminate cutaneous blood flow in the treated skin, eliminating convective heat exchange. Together the cooling applicator and its ‘folded’ design result in selective cooling of fat while extracting energy and ultimately causing apoptosis of adipocytes. This is followed by a gradual inflammatory response leading to even more adipocyte damage and eventual phagocytosis of the apoptotic debris.
Patient selection
Appropriate patient selection is vital to ensure positive results and patient satisfaction. Ideal candidates for cryolipolysis are those individuals who are relatively fit with stubborn areas of fat accumulation that do not respond to diet and exercise. Ideal areas to treat include the flanks, abdomen, and mid to lower back. Other common areas where fat may accumulate, such as the hips, thighs, buttocks, upper arms, and neck, may also respond well to this procedure and, therefore, further investigation of additional potential treatment sites is both warranted and ongoing. The ‘sandwich’ design of cryolipolysis treatment heads has been modified to provide separate attachments appropriate for treatment of various body sites and sizes of local adiposities. Importantly, as cryolipolysis does not directly affect the epidermis, patients of all Fitzpatrick skin types and ethnicities may be safely treated.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
