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Cancer Patent Abstract
Noninvasive pain treatment of skeletal cancer metastases in cancer
patients utilizing planar or focused ultrasound. The ultrasound
energy preferably targets at the Periosteum or immediate soft-bone-tissue
interface, where local sensory pain receptors are directly affected
by the growing tumor, to generate heat to destroy local sensory
pain receptors so as to interrupt or block the pain feedback pathway
to the central nervous system.
Cancer Patent Claims
What is claimed is:
1. A method for reducing pain due to bone cancer, said method comprising:
targeting a region of interest with an imaging modality comprising
ultrasound; emitting therapeutic ultrasound energy from an ultrasound
radiating surface and focusing the emitted therapeutic ultrasound
energy on the region of interest; producing tissue damage to nerves
supplying the region of interest; wherein imaging and therapy transducers
are incorporated into a single unit whereby imaging and therapy
can be accomplished with the same control interface, and wherein
the emitted ultrasound energy comprises HIFU and said focusing the
emitted ultrasound causes the formation of microbubbles in the region
of interest, said microbubbles producing a hyperechoic spot on said
imaging modality with said hyperechoic spot being utilized in the
imaging modality to monitor the progress of the nerve tissue damage.
2. The method of claim 1 wherein the ultrasound radiating surface
is located external to the body and the ultrasound energy is delivered
extracorporeally.
3. The method of claim 1 wherein the damage to the nerves is sub-lethal
tissue and/or cellular damage, causing a temporary, reversible loss
in nerve conduction.
4. The method of claim 3 wherein the sub-lethal damage the nerves
is to the myelin sheath surrounding an individual axon.
5. The method of claim 3 wherein the applied acoustic intensity
is delivered at a level sufficient to terminate nerve conduction,
but not sufficient to irreversibly damage the surrounding tissue.
6. The method of claim 1 wherein the emitted ultrasound energy
produces lethal tissue damage to predetermined nerves proximal to
the region of interest.
7. The method of claim 1 wherein coupling between the HIFU transducer
and a patient is accomplished with a water path, a gel couplant,
or a hydrogel.
8. An apparatus for use in reducing pain due to bone cancer, said
apparatus comprising: ultrasound emitting means having an ultrasound
radiating surface adapted for placement non-invasively on a patient's
skin; said ultrasound emitting means being selectively operable
to emit a selected level and/or frequency of ultrasound from said
ultrasound radiating surface to a taraet site proximal to a bone
cancer site; wherein said level and/or frequency of said ultrasound
is selected to produce sub-lethal or lethal nerve damage at the
target site proximal to the bone cancer site and is further selected
to produce a hyperechoic spot at the target site; an imaging means
for locating and displaying the bone cancer site, said imaging means
monitoring the hyperechoic spot as an indicator of pain reduction
progress; wherein the ultrasound emitting means and the imaging
means are incorporated into a single unit with the same control
interface.
9. The apparatus of claim 8 wherein said imaging means comprises
one of Computerized Axial Tomography, magnetic resonance, X-ray
or ultrasound.
10. The apparatus of claim 9 wherein the imaging ultrasound comprises
diagnostic ultrasound.
11. The apparatus of claim 8 wherein the nerve damage is lethal
nerve damage located at the periosteum, or the immediate soft-bone-tissue
interface or the myelin sheath.
12. The apparatus of claim 8 wherein the nerve damage is sub-lethal
nerve damage located at the myelin sheath.
13. The apparatus of claim 8 wherein the ultrasound comprises planar
or focused therapeutic ultrasound.
14. The apparatus of claim 13 wherein said ultrasound operates
at a frequency range of 0.75-7.0 MHz.
15. The apparatus of claim 13 wherein said ultrasound comprises
High Intensity Focused Ultrasound.
Cancer Patent Description
FIELD OF THE INVENTION
The present invention utilizes planar or focused ultrasound applied
transcutaneously to reduce bone pain of skeletal metastases in cancer
patients.
BACKGROUND OF THE INVENTION
Bone metastasis is one of the most common causes of pain in cancer
patients. In the United States, it is estimated that of 1.4 million
patients who will be diagnosed with cancer, 30% to 70% will develop
skeletal metastases. In one study, the prevalence of pain was shown
to be 55% of ambulatory patients, and 46% of those patients reporting
pain received inadequate analgesics. Each year there is estimated
150,000 painful bone metastases cases from advanced lung, breast,
and prostate cancer in the United States.
Bone cancer is a growth found in any part of the bone. Most bone
cancers develop predominantly from bone, cartilage, muscle, fibrous
tissue, fatty tissue or nerve tissue. Primary bone cancer originates
in the bone itself. The most common primary malignancies that metastasize
to the bone are breast, kidney, lung, and prostate. The most common
sites of metastasis are the vertebrae, pelvis, and long bones. Secondary
bone cancers, which are more common than primary cancers, spread
from other cancerous cells in the body. Primary and Secondary types
of bone cancer are described below.
Primary Bone Cancer: A. Osteosarcome: the most common type of primary
bone cancer, develops in new tissues of growing bones, particularly
the knees, upper legs, upper arms. Patients often children and young
people between 10 and 25 years old. B. Ewing's Sarcoma: this sarcoma
begins in immature nerve tissue in the bone marrow of the body's
large bones, i.e. pelvis, upper legs, ribs and arms. Ewing's sarcoma
affects children and young adults. C. Chondrosarcoma: this usually
arises in the cartilage, soft connective tissue of the pelvis, upper
legs and shoulders. This type of malignancy most frequently affects
adults over 50 years old.
Secondary Bone Caner: It is more common than primary bone cancer
and usually occurs later in life. Cancers that tend to spread rapid
to bone are breast, lung, prostate, thyroid, and kidney. Pain usually
results when a tumor pushes on bones, nerves, or other organs in
the body.
Current pain control treatments include: A. Surgery to remove all
or part of the affected bone. B. Chemotherapy involves the use of
drugs that target the given tumor cells. Significant side effects
are problematic. C. Radiation Therapy utilizes X-ray or other radioactive
source to destroy the development of abnormal cells. Similar to
chemotherapy, radiation may impact normal tissues. D. Hormone Therapy
is used to stem secondary bone cancers of the prostate and breast.
E. Analgesic Drugs: radiopharmaceuticals, bisphosphonates, calcitonin
and others to treat pain via blocking pain pathways or inhibit local
growth factors. F. Radiofreqency ablation on benign lesion of bone
(osteoid osteoma) targeting at nidus, where composed of a variably
calcified meshwork of bony trabeculae on a background of fibrous,
vascular, and nerve tissue. Percutaneous RF ablation treats the
margin of the lesion at the soft-tissue-bone interface for pain
reduction.
The above therapies may have serious side effects and limitations
can include: A. Poor therapeutic response or toxicity from chemotherapy.
B. Intolerable analgesic related side effects may develop with increasing
analgesic doses. C. Limited patients are suitable for radiation
therapy because of radiation insensitivity of the neoplasm or limitations
of radiation dose that can cause damage to normal structure and
healthy cells.
Although terminal patients undergo combinational treatment plan,
the current treatments are ineffective to relieve pain.
Tumor metastasis to bone is associated with bone destruction and
new bone formation. Bone pain often results from the tumor impinging
on nerve tissue, disrupting normal bone remodeling process, and
displacing bone. The pain is usually described as a deep, aching
over the site of the involved bone.
The sensory receptors within the human body are sensitive to tissue
damaging or stimuli that are prevalent in skin, muscle, joint, bone
and other connective tissues. Those nociceptors (sensory receptors)
are sensitive to response to mechanical, thermal, and chemical cutaneous
stimuli. It is believed that nociceptor sensitization is a physiologic
mechanism of persistent pain. Once nociceptors activated locally,
it transduces chemical, mechanical, or thermal stimuli into afferent
impulses that enter the nervous system to the brain for pain perception.
Particularly, A-.delta. mechanoreceptors and C-nociceptors appear
to be localized to connective tissue between muscle fibers and in
blood vessel walls or tendons, and in the joint capsule and periosteum.
Particularly, numerous studies have shown that the periosteum,
which is comprised of fibrous connective tissue sheath that covers
the external surface of all bones, is densely innervated by both
sensory and sympathetic fibers. Nerves are distributed to the Periosteum
and accompany the nutrient arteries into the interior of the bone.
Fine nerve endings are found in bone marrow, periosteum, cortex,
and associated muscles and ligaments. The prevailing opinion is
that bone pain arises predominantly from the densely innervated
periosteum, where is the area of interest for ablating local pain
receptors utilizing ultrasound to reduce bone pain.
SUMMARY OF THE INVENTION
The present invention is directed to noninvasive or minimal invasive
pain treatment of skeletal cancer metastases in cancer patients
utilizing planar or focused ultrasound. The ultrasound energy preferably
targets at the Periosteum or immediate soft-bone-tissue interface,
where local sensory pain receptors are directly affected by the
growing tumor, to generate heat to destroy local sensory pain receptors
so as to interrupt or block the pain feedback pathway to the central
nervous system.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a single unit comprising imaging and therapy
transducers for treating nerves.
FIG. 2 illustrates a control interface for controlling imaging
and therapy emitted from the single unit of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is directed to noninvasive pain treatment
of skeletal cancer metastases in cancer patients utilizing planar
or focused ultrasound.
A preferred method of noninvasive pain treatment includes interrupting
the activation of nociceptors and blocking pain feedback pathway.
A preferred method is described below.
One or more therapeutic target sites 9 (FIG. 1) are located by
use of an imaging modality which, preferably, also displays the
location of the bone cancer site 11. The imaging guided system can
be Computerized Axial Tomography (CT), Magnetic Resonance (MR),
X-Ray, ultrasound, such as diagnostic ultrasound 1 or other imaging
modality.
Utilizing a planar or focused ultrasound transducer 3 with frequencies
range from 0.75 to 7.0 MHz, the ultrasound 4 is applied to the patient
transcutaneously with acoustic coupling to the skin 6 using, for
example, a water path, gel couplant or hydrogel 5. The transcutaneous
coupling may utilize a suitable acoustic delay member, such as a
water column or a specified geometric shape hydrogel (e.g. a hydrogel
cone).
Local heating of the nerve endings at the Periosteum (about 45.degree.
C. to 67.degree. C.) is generated utilizing acoustic power (preferably
ranging from 5 to 1000 W/cm.sup.2) thereby resulting in destruction
of the nerve tissue 8 proximal to a bone cancer site 11. High Intensity
Focused Ultrasound (HIFU) is the preferred method for generating
the necessary heat at the nerve endings.
Preferably, the ultrasound is delivered to the target site using
the image-guided system 2 to identify and mark therapeutic sites.
It is also preferred that the ultrasound transducer is operated
with the image-guided system to allow both treatment and monitoring
functions. If the target site 9 can be readily identified when viewed,
no image guidance system is necessary as visual guidance is acceptable
in this instance. Preferably, when placing a therapeutic lesion
in the region of interest, a hyperechoic spot 12 may be created
due to the production of microbubbles by HIFU, and this hyperechoic
spot 12 can be utilized in the ultrasound image to monitor the progress
of the pain treatment therapy.
Alternatively, image guided therapeutic HIFU may be utilized to
destroy nerves in the Periosteum at a predetermined location 10
on the bone 7 and thereby block or reduce pain transmission from
the bone.
If desired, the acoustic intensity can be controlled such that
damage to the nerves is sub-lethal tissue and/or cellular damage
thereby causing a temporary and reversible loss in nerve conduction.
In such instances, the sub-lethal damage is preferably directed
to the myelin sheath which surrounds individual nerve axons. Heating
of the nerves to within the range of about 40.degree. C. to about
45.degree. C. is believed to be satisfactory to accomplish the sub-lethal
damage.
The imaging and therapy transducers 1, 3 used to treat the nerves
8 may be separate units, but connected by a rigid construction or
the imaging and therapy transducers 1, 3 may be incorporated into
a single unit 14, so that imaging and therapy can be accomplished
with the same control interface 21 (FIG. 2).
While the invention has been described with reference to preferred
embodiments it is to be understood that the invention is not limited
to the particulars thereof. The present invention is intended to
include modifications which would be apparent to those skilled in
the art to which the subject matter pertains.
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