Surgery: kinesitherapy – Kinesitherapy – Ultrasonic
Reexamination Certificate
1999-06-28
2001-12-04
Lateef, Marvin M. (Department: 3737)
Surgery: kinesitherapy
Kinesitherapy
Ultrasonic
Reexamination Certificate
active
06325769
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to skin therapy. More particularly, the present invention relates to the use of such therapy for reducing rhytides of the skin (i.e., skin wrinkles), especially facial rhytides.
Human skin is basically composed of three layers. The outer, or visible layer is the stratum corneum. The stratum corneum is essentially a thin layer of dead skin cells that serves, among other things, as a protective layer. Below the stratum corneum is the epidermis layer. The epidermis layer is a cellular structure that forms the outermost living tissue of the skin. Below the epidermis layer is the dermis layer that contains a variety of tissues such as sweat glands, nerves cells, hair follicles, living skin cells, and connective tissue. The connective tissue gives the dermis layer body, shape, and support. Since the epidermis layer lies on top of the dermis layer, the shape, smoothness, and appearance of the epidermis layer is in part determined by the shape of the dermis layer (and largely the connective tissue). Thus, variations in the shape of the connective tissue tend to appear as variations in the epidermis layer.
There are a number of methods currently being used to reduce or eliminate skin wrinkles, particularly facial skin wrinkles. Some of these methods include the use of lasers, cryo-peeling, chemical-peeling, and dermabrasion. These methods appear to stimulate or irritate the dermis layer so that a biological response results that produces new connective tissue which in turn reduces or eliminates skin wrinkles in the treated area.
However, the cryo-peeling, chemical-peeling, dermabrasion and laser ablation methods generally result in significant damage to the epidermis and dermis layers. In these methods, the epidermis layer may be peeled or burned away. This presents several problems: opportunistic infections may invade the dermis layer and thus complicate or prolong recovery; the procedure may cause a patient significant discomfort and pain; and the skin may appear raw and damaged for a significant period of time (on the order of weeks or months) while the healing process takes place. All of these side effects are considered undesirable.
Therefore, one object of the present invention is to provide an improved method and apparatus for reducing or eliminating skin wrinkles.
Another object of the present invention is to provide a method and apparatus for reducing skin wrinkles that does not substantially damage the epidermis layer of the skin.
SUMMARY OF THE INVENTION
The overall concept of the present invention relates to methods and apparatus for therapeutic treatment of skin using ultrasound. In particular, the present invention relates to wrinkle reduction and skin rejuvenation by controlled application of ultrasound energy into the dermis layer. The ultrasound energy triggers a biological response that causes synthesis of new connective tissue in the dermis through activation of fibroblast cells in the dermis without causing or requiring significant irritation or damage to the epidermis. One purpose of the present invention is to provide a cosmetic improvement in the appearance of the skin meaning that the treated skin surface will have a smoother, rejuvenated appearance. The present invention achieves this without the need to induce significant damage to the epidermis layer of the skin.
These and other objects are achieved by the present invention which, in one embodiment, provides a method of rejuvenating human skin, the method comprising applying a focused ultrasound beam to a region of human skin to stimulate or irritate a dermis layer in the region of the skin so as to cause a change in the dermis layer of the skin that results in a change in a smoothness of the epidermis layer of the skin.
According to another embodiment of the invention, an apparatus for rejuvenating human skin is provided, the apparatus comprising an ultrasound transducer, coupled to an ultrasound driver, for propagating ultrasound waves into a region of human skin in response to signals from the ultrasound driver, and a control device constructed and arranged to focus the signals provided by the ultrasound driver circuit to control the ultrasound waves provided by the ultrasound driver so as to stimulate or irritate a dermis layer in the region of the skin to cause a cosmetic improvement in an appearance of the skin.
According to another embodiment of the invention, a transducer configuration, capable of applying focused ultrasound energy to a dermis region of human skin is provided. The transducer configuration comprises a transducer and an acoustical waveguide disposed adjacent to an ultrasound emitting surface of the transducer, wherein a thickness of the acoustical waveguide determines a depth focus of the ultrasound energy in the skin.
According to another embodiment of the invention, a method of rejuvenating human skin is provided, the method comprising applying a focused ultrasound beam to a region of human skin to generate a shock wave to mechanically disrupt a dermis layer in the region of the skin so as to cause a change in the dermis layer of the skin that results in a change in a smoothness of an epidermis layer of the skin.
In a further aspect of the invention, the acoustic pulses which are used to treat the skin have pressure amplitudes that are sufficiently high to introduce non-linearity, that is to say, the speed of propagation of the pulses through the target region of dermis will be higher than the normal speed of sound propagation through skin. For example, in skin, the normal speed of sound is approximately 1480 m/sec. However, at high enough amplitudes, skin tissue becomes more elastic and the speed of propagation can increase to as high as about 1500 m/sec. The magnitude of this non-linear behavior varies not only with pulse amplitude, but also with the duration of the pulse. Typically, the non-linear behavior will be exhibited, with acoustic pulses having intensity (within the target region) of about 500 to about 1000 watts/cm
2
and is preferably applied by pulses having durations ranging from about 10 nanoseconds to about 200 microseconds.
One result of this non-linearity is distortion the waveform of the pulses and they travel through the skin, converting waves typically having Gaussian amplitude (pressure) profile to waves that presents a much sharper leading face, essentially a “shock-wave” at the target region below the surface of the skin. In a normal wave propagation mode, there is essentially no net movement of dermal material. However, when acoustic waves exhibit non-linearity, material does move, creating a negative pressure, or vacuum effect, in the tissue in the wake of the pulse. This negative pressure can induce the tissue damage of the present invention, tearing tissue structures apart, heating the region and, thereby, triggering the synthesis of new connective tissue.
The invention is particularly useful for reducing the appearance of human skin wrinkles. Embodiments of the present invention can provide a smoother, rejuvenated appearance of the skin, without adversely damaging the epidermis layer of the skin.
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Anvari, B. et al., “Cryogen Spray Cooling in Conjunction With Laser Treatment of Se
Collapeutics, LLC
Engellenner Thomas J.
Lateef Marvin M.
Mercader Eleni Mantus
Nguyen Tram Anh T.
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