Biopsy cannula

The present invention provides a biopsy device for obtaining tissue samples while preserving the relational aspects of the tissue substructure and architecture. The biopsy device comprises a cannula housing and a spring activated sharpened blade which is slideable engageable with the cannula housing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a medical instrument that can obtain a 
tissue sample. More particularly, the invention relates to a biopsy 
needle. 
2. Description of the Background Art 
In the treatment of disease or pathological conditions it is often 
necessary to examine a sample of tissue to detect pathological changes in 
order to accurately diagnose and render proper treatment. In many 
instances, a knowledge of the exact cytoarchitecture of the tissue is 
critical to diagnosis of the specific pathological condition. When such 
tissue samples are removed by use of an aspirating needle such as that 
disclosed is U.S. Pat. No. 3,595,217 to Rheinfrank, the relational aspects 
of tissue substructure and infrastructure are not maintained. 
There is a growing need for a device capable of obtaining brain tissue 
samples, for example, which samples retain the relational aspects of the 
brain tissue architecture. Biopsies of brain tissues are often performed 
for the diagnosis and localization of peripherally located brain tumors, 
infectious diseases, such as viral infections, including herpes simplex of 
the temporal lobe, Acquired Immune Difficiency Syndrome with 
toxoplasmosis, SSPE (Subacute sclerosing panencephalitis), neurolipidoses 
(storage diseases) and Alzheimer's disease. Accurate diagnosis in disease 
states such as those cited depend on the examination of brain tissue 
obtained by biopsy. The accuracy of the diagnosis will often depend upon 
preservation in the tissue sample of the relational aspects of the tissue 
architecture. 
Alzheimer's disease is considered one of the most pressing problems in the 
1980s, being the fourth largest cause of death in the United States. Based 
on pathological evaluations, it is estimated that half of all the patients 
in the United States with dementia have untreatable Alzheimer's disease. 
On the other hand, biopsy for prognosis information is important. Ten to 
20 percent of all dementias or 20-40% of the remaining 50% can be 
successfully treated if diagnosed correctly. An accurate tissue biopsy 
will detect these treatable cases and be efficacious. 
The neuropathologist uses paraffin embedding and paraffin microtome 
sectioning and frozen sectioning. Using various techniques, multiple 
stains according to the cellular material of interest are used for study. 
The study is examined grossly under the light microscope (.times.40, 
.times.100, .times.400, .times.1000); changes of the neurons, fibrous 
connective tissue, glia, and vascular structures are observed. Nerve cell 
loss is important. Abnormal interneuronal material can indicate abnormal 
stored material: (1) neurolipidoses (ganglioside--Tay Sachs disease, 
Sphingomyelin--Neimann-Pick disease); (2) degeneration processes (senility 
pigment--lipofuscin, Alzheimer's neurofibrillary degeneration, Parkinson's 
disease--Lewy bodies and various viral inculsion bodies, e.g., SSPE, 
rabies). 
Special techniques involve transmission electron microscopy, 
histoenzymological examinations of fresh brain and immunostaining using 
peroxidase antibodies. 
Tissue lesions can be demonstrated by hemorrhages, atrophy, necrosis, 
cerebral edema, demyelination, inflammatory lesions, and connective tissue 
and vascular changes. Artifacts caused by unnecessary "rough handling" of 
brain tissue as demonstrated by biopsy suctioning, biopsy crushing, biopsy 
stretching, and biopsy ripping can erroneously cause hemorrhages, cerebral 
swelling, vascular injury and cell injury and interfere with diagnostic 
accuracy. 
The brain biopsy information is correlated with clinical data and ancillary 
investigations. 
A number of devices have been developed to obtain biopsy of tissue from 
individuals from areas such as the brain. Biopsy cannulas are often used 
by neurosurgeons, in some cases with the aid of fluoroscopy, computerized 
tomography, Magnetic Resonance Imaging, or ultra-sonography. Among the 
devices which were available prior to the present invention are a cannula 
which uses suction by a syringe to obtain a biopsy; a device in which 
forceps protrude from a cannula to obtain a sample, and are withdrawn; and 
a device which comprises a spiral cutting tip in a cannula to obtain 
biopsy samples. In devices such as the foregoing examples, the samples are 
traumatized, significantly affecting the quality and accuracy of the 
pathologic review. Suction of brain tissue into a needle disrupts the 
relational architecture of the tissue and may also disrupt the 
cytoarchitecture, as will compression caused by forceps or the grinding 
action of a spiral cutting edge. In addition, the trauma caused by removal 
of tissue samples by devices such as those described often leads to 
hemorrhage in the area from which the tissue sample was removed and causes 
protracted recovery of the patient. 
Other biopsy devices have been devised which operate along principles 
described above. For example, U.S. Pat. No. 4,461,305 discloses an 
automated biopsy device which has a rotary mounted cutting blade which 
severs the tissue for extracting biopsy tissue from the female uterine 
cervix. A biopsy device developed to primarily obtain endocervical canal 
tissue samples was disclosed in U.S. Pat. No. 4,243,048, which has a 
non-metal "nose cone" which provides a guiding protuberance and a hollow 
tubular member telescopically fitted on the shaft which has an annular 
cutting element on the distal end and a hollow inner chamber which 
receives the tissue specimen. U.S. Pat. No. 3,590,808 discloses a biopsy 
device for use in the gastrointestinal tract in which a tissue sample is 
drawn into the hollow end of the device by vacuum and a pneumatically 
operable knife severs the biopsy sample. U.S. Pat. No. 3,173,414 discloses 
a combination of a biopsy probe and endoscope which utilizes a suction 
pump to draw in the severed tissue sample. 
Examples of needle biopsy devices such as are shown in U.S. Pat. No. 
2,198,319 and U.S. Pat. No. 3,001,522 disclose needles which are sharpened 
to sever the tissue and provide space within the shaft of the needle for 
storing the selected tissue and which may incorporate a gripping 
mechanism. U.S. Pat. No. 4,600,014 discloses a transrectal prostate biopsy 
device which is an improvement on the Travenol TRU-CUT.RTM. biopsy needle. 
It is an object of the present invention to provide a biopsy device for 
obtaining biopsy samples from tissues, and preferably from brain tissue, 
wherein the tissue removed from the individual retains the relational 
aspects of the tissue substructure and architecture. It is a further 
object of the present invention to devise a biopsy device which is capable 
of removing a tissue sample for maximally accurate pathological 
examination and be capable of minimizing cerebral injury, swelling, or 
arterial vessel injury, and subsequent blood clot formation. 
SUMMARY OF THE INVENTION 
A biopsy device is provided which acts as a cutting tool which cores out a 
cylinder of tissue with minimal pressure, which will allow the 
preservation of the tissue and cytoarchitecture. The device is composed of 
a round thin-walled needle or cannula and a thin blade which is housed in 
an axial slot in the outer circumference of the needle or cannula housing. 
An opening extends coaxially the length of the needle or cannula from the 
proximal to the distal ends of said cannula housing. The blade slides 
along channel guides in the axial slot and is initially locked into a 
position parallel to the length of the needle by the channel guides. The 
spring-loaded blade, prior to engagement for cutting, is held at an angle 
parallel to the shaft of the needle by engaging the distal end of the 
blade with a shoulder (blade restraint or blade rest) on the Periferal 
surface of the needle shaft. Once the needle or cannula is inserted to the 
desired depth, the blade is engaged for tissue cutting action by 
withdrawing the blade to release it from the distal blade rest, which 
releases the blade tip from its parallel position. The spring-loaded blade 
in its preferred position curves, in a preferred embodiment at a 
35.degree. angle, and thus when released from its distal perch, will curve 
toward the floor of the shaft of the needle. As the surgeon pushes the hub 
of the blade inward in a longitudinal direction, the blade will sever the 
tissue, and at the same time, close off the distal channel of the needle. 
The needle is then withdrawn, containing the non-crushed biopsy sample of 
approximately 0.4-0.8 cc. The needle also will push aside cerebral 
arteries as it advances, preventing hemorrhage of these arteries and 
removing the vessels from the cutting field. Since the cutting by the 
blade is done within the needle or cannula shaft itself, there will again 
be no chance to damage or sever the cerebral vessels adjacent the blade 
during tissue engagement and cutting of the tissue. One advantage of the 
present invention over tissue sampling devices previously available is 
that the present invention cuts a cylinder of tissue and then amputates 
the base of the cylinder by a sharp blade cut, which prevents tissue 
tearing which occurred when tissue samples were extracted by suction or by 
stretching the base until tissue tearing occurred. Tissue tearing at times 
ruptured arteries and caused tissue injuries several centimeters removed 
from the biopsy region, which in critical neural anatomical areas would 
cause severe morbidity or mortality. 
A further advantage of the present invention is that relatively large 
biopsy samples, approximately 0.4-0.8 cc, can be obtained, as opposed to 
the small samples of about 0.05 to 0.1 cc which could be obtained from 
other biopsy needles. The device of the present invention is also safer to 
use than those which rely on suction to sever the tissues from the area 
being biopsied in that the suction caused trauma to the surrounding 
tissue, which resulted in brain swelling and intracerebral hematoma, which 
can cause stroke and/or death in the individual from whom the tissue is 
being removed. 
An additional advantage of the present invention is the simple construction 
which will increase the ease of manufacture and of sterilization of the 
device. The two-part construction consists of a blade and a cannula 
housing. The blade may be replaced after each biopsy, insuring that a 
sharp blade will prevent tissue tearing with every biopsy taken. In 
addition, the cannula housing is reusable, which will increase the economy 
of use of this biopsy device. 
The biopsy device of the present invention can also be applied to organs 
other than the brain, such as kidney, liver, bowel, testes, lung, muscle, 
prostate, breast, cervix and ovary, which organs are often biopsied and 
for which the relational tissue architecture must be maintained for an 
accurate diagnosis of pathological states. The size of the needles, both 
in gauge and length, in which the blade is adapted, can be varied to suit 
individual organ and the special requirements of each type of biopsy 
specimen required. The advantages and embodiments of the present invention 
will become apparent from the following description when read in 
conjunction with the drawings. 
In a preferred embodiment, the present invention comprises a biopsy needle 
comprising a generally cylindrical housing having proximal and distal ends 
and a coaxially extending opening therethrough, the housing having an 
axial slot therein, adjacent, but spaced from, the distal end, support 
means on the housing for retaining a blade in position in the slot, 
shoulder means near the distal end of said housing adjacent to the distal 
end of said axial slot for holding the distal end of a flexible blade out 
of the opening but allowing the distal end of the blade to contract into 
said opening for cutting a specimen when the blade is disengaged relative 
to said shoulder, and a flexible blade having proximal and distal ends, 
positioned in said axial slot of said housing and slideably engageable 
with the housing, the distal end of the blade being sharpened and spring 
actuated for contracting into the opening of the housing when disengaged 
from said shoulder means, wherein the width of said blade is fixed 
relative to the width of said axial slot such that said blade when engaged 
in said housing assumes a curvilinear shape.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIG. 1, a preferred embodiment of the biopsy needle of the 
present invention for use as a brain cannula, which comprises a blade 19, 
a blade hub 10, a cannula 26, a cannula hub 12, channel guides 13, 14 and 
15, a blade restraint 16 on the superior edge of the cannula, a cannula 
cutting edge 17, a blade cutting edge 18. When the flexible blade 19 is 
inserted into the cannula housing 26, it conforms to a curvilinear shape 
to fit into the channel guide in the hub 27 and the channel guides 13, 14 
and 15 of the cannula. The flexible blade is made to be spring actuated, 
in a preferred embodiment, by being prebent to form a leaf spring means 
for contracting into the channel or opening which extends coaxially 
through the cannula housing. The blade, when it is not engaged by the 
blade restraint (16) of the cannula, ends flexibly at a 35.degree. angle 
for a length of 12.7 mm at the distal portion in a preferred embodiment 
for use as a brain cannula. When the cutting blade is engaged in the blade 
restraint 16 of the cannula, the guillotine blade is straight, and 
non-engaged with respect to the tissue as can be seen in FIG. 2A, in which 
the cutting blade 19 is demonstrated in a lateral view in the 
spring-loaded resting position 2A (restraint engaged) and the tissue 
engaged position 2B. In a preferred embodiment, the blade restraint is a 
shoulder means located adjacent to, but not at, the distal end of the 
cannula housing at the distal end of the axial slot. 
The guillotine blade is engaged in the cannula housing by contacting the 
guide channels 13, 14 and 15 seen in FIG. 4, and is held in the 
spring-loaded resting position by the blade restraint 16 on the superior 
surface 26a of the cannula 26. 
As seen in FIGS. 7, 8 and 9, when the blade is withdrawn 2 mm, and thereby 
released from the blade restraint 16 of the cannula, the kinetic energy of 
the spring-loaded blade (0.25-0.5 PSI) causes the blade to bend toward the 
cannula floor due to the 35.degree. bend of the spring-loaded blade and 
causes the blade to contact the tissue within the cannula chamber. Then as 
the blade 19 is moved forward toward the distal end of the cannula housing 
by pressure on the blade hub 10, as seen in FIGS. 9 and 10 the cylinder of 
tissue within the cannula chamber is severed from the surrounding tissue. 
The blade is moved forward until the tip of the blade 18 contacts the 
floor of the cannula housing, at which time the tissue sample within the 
cannula is completely severed from the organ proper from which the organ 
sample is being taken. The organ being sample, in the preferred 
embodiment, the brain, remains quiescent. The cannula and blade, which now 
contain in the cannula chamber a section of brain tissue, is then 
carefully retracted from the brain with minimal injury due to the biopsy 
procedure. 
The distal portion of the blade, when contacting the floor of the cannula 
housing, serves to keep the biopsy sample tissue in place in the cylinder 
until the sample is withdrawn from the body. After removal from the body, 
the blade is withdrawn and the cannula containing the biopsy specimen is 
placed in a solution appropriate for the diagnostic tests to be performed. 
The tissue sample is then gently removed from the cannula, while 
preserving the architecture of the sample. 
It will be obvious to those of skill in the art that the biopsy needle of 
the present invention may be used to obtain tissue samples from other 
parts of the body besides the brain. It may be used on humans and animals 
alike. The length and diameters described in the present application, and 
the accompanying drawings, may be modified to suit particular applications 
and any such modifications will be seen by those of skill in the art to 
fall within the spirit and scope of the present invention.