Note: Descriptions are shown in the official language in which they were submitted.
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Title: NEEDLE HAVING IInIJLTIPLE ELECTRODES
FIELD OF ThIE INVENTION
[0001) The present invention relates to needles having multiple
electrodes. In particular, the invention relates to needles having bipolar and
tripolar electrode arrangements which may be used in electromyography.
EACKGROUND OF THE INVENTION
[0002, Needles are frequently used in electromyography (EMG) for
detecting electrical signals within the body. Commonly, needies used in
electromyography have one or two electrodes, termed monopolar and bipolar,
respectively.
[0003] if the diameter of a needle is too large, it can cause significant
pain to the person in whom it is inserted. Thus it is desirable to have as
small
a diameter as possible.
[0004] For needles having bipolar electrodes, one of the electrodes is
usually a reference canductor while the other is used as an active conductor.
A common or ground conductor is placed on the skin externally of the point at
which the body's electrical activity is being monitored. This placement of the
common conductor on the skin takes time during the EMG set up procedure.
Further, the signal quality achieved with a common electrode remote from the
measurement point of the active and reference electrodes is sub-optimal.
[0005] Some needles use a beveled tip. That is, the needle tip is cut at
an angle from one side to the other, presenting a substantially elliptical
face in
the plane of the cut (assuming that the needle is of circular cross-section).
Secause of the elliptical shapes of the electrodes exposed on the elliptical
face, the distance betuveen the central electrode and the outer concentric
electrode is not uniform across the exposed elliptical face of the needle at
its
tip. This lack of uniformity of distance between the two electrodes can lead
to
inaccuracies in the signal detection.
[0006' A further problem with existing beveled tip concentric needles is
that when they are constructed with a small outer diameter, the gap between
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the active and reference electrodes is often quite small, leading to lower
amplitude signals and smaller efFective measurement area. There is also a
tendency for the electrodes to short circuit after the tip becomes worn by
repeated insertions. Also, the area of the exposed surface of the inner
conductor is small, resulting in low signal amplitudes.
SUMMARY OF THE iNV~NTIt~N
[0007] In one aspect, the invention relates to a needle for
electromyography having a distal sharpened tip portion and a shaft, the
needle comprising
first, second and third concentrically arranged electrodes
for acting as respective active, reference and ground conductors during
electromyography; and
first and second insulation layers for separating the first
and second electrodes and the second and third electrodes, respectively;
wherein the third electrode at least partly defines an outer diameter of the
shaft and the shaft has a substantially constant outer diameter proximally of
the distal top portion.
[000] Preferably, the needle is formed from a needle blank having first
and second concentric electrodes. An outer insulation layer is formed around
the needle blank and a third electrode is formed around the outer insulation
layer.
[0009] The third electrode is preferably exposed at least to some extent
along a shaft portion of the needle. The first and second concentric
electrodes are preferably exposed at least to some extent along a tip portion
of the needle.
[0010] In a preferred embodiment, the outer diameter of the needle is in
the range 0.3mm to O.fiSmm. The needle is preferably formed so that an
outer diameter of the third electrode is substantially the same as an
outermost
diameter of the needle blank, which is substantially the same as an outermost
diameter of the needle.
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(0011] In a further aspect, the invention relates to a method of forming
a needle, comprising providing a needle blank having first and second
concentric electrodes and an outer insulation layer and forming a third
concentric electrode around the needle blank.
[0012] In a still further aspect, the invention relates to a method of
forming a needle, comprising providing a needle blank having first and second
concentric electrodes, forming an outer insulation layer around the needle
blank and forming a third concentric electrode around the outer insulation
layer.
[0013] According to these method aspects, it is preferred that the third
electrode is formed along a shaft portion of the needle, away from a tip
portion
of the needle. Further, it is preferred that the needle is formed so that an
outer diameter of the third electrode is substantially the same as an
outermost
diameter of the needle blank, which is substantially the same as an outermost
diameter of the needle.
[0014] In yet another aspect, the invention relates to a method of
forming a needle, comprising the steps of: providing a needle blank having
first and second concentric electrodes, the first electrode being formed
inwardly of the second electrode; removing a portion of the second electrode
along a shaft of the needle; adding an insulation layer around the needle at
least along the part of the shaft from which the portion of the second
electrode
was removed; providing a conductor layer around the insulation layer; and
cutting excess added insulation material from the needle so that the outer
diameter of the needle is the same as the outer diameter of the needle blank
whereby a third concentric electrode is formed from the conductor layer at
least partly along the portion of the shaft from which the portion of the
second
electrode was removed.
(0015] In yet another aspect, the invention relates to a method of
forming a needle, comprising providing a needle blank having first and second
electrodes, providing an insulation material around at least part of the
needle
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blank and providing a conductive material around at least part of the
insulation
material to form a third electrode.
[0016] In one embodiment, the conductive material comprises a
conductive sheath, which is preferably in the form of a metallic tube. In
another embodiment, the conductive material is plated or coated on the
outside of the insulation material.
[0017] Preferably, the method includes removing a portion of the
needle blank before providing the insulation material. The portion removed
from the needle blank is preferably substantially tubular or sheath like.
Preferably, the first, second and third electrodes are concentrically
arranged.
Preferably, the first electrode is an active conductor and is disposed
inwardly
of the second electrode, the second electrode is a reference conductor and is
disposed inwardly of the third conductor and the third electrode is a common
or ground conductor.
[0018] In a preferred embodiment of the method, one end of the needle
blank is sharpened so as to provide a substantially conical or frustoconical
shape thereto. Alternatively, the needle blank may have one end sharpened
so as to provide a beveled tip shape thereto.
[0019] Preferably, the needle is formed so as to have an outer diameter
along a shaft thereof substantially the same as an outermost diameter of the
needle blank.
[0020] In a still further aspect, the invention relates to a method of
forming a needle, comprising providing a needle blank having first and second
concentric electrodes, providing a conductive material around at least part of
the needle blank and injecting an insulating material between the needle
blank and the conductive material.
[0021] In another aspect, the invention relates to a needle for
electromyography having first and second electrodes and a sharpened tip,
wherein the first and second electrodes are exposed on said tip such that the
first and second electrodes are separated by a constant gap.
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10022] The tip is preferably sharpened so as to have a substantially
conical or frustoconical shape. The first and second electrodes are preferably
concentrically arranged. The first electrode extends along a central
longitudinal axis of the needle. The first and second electrodes are separated
by a concentrically arranged insulation layer and the second electrode defines
an outer diameter of the needle.
(0023] In a further aspect, the invention relates to a method of forming
a needle, comprising providing a needle blank having first and second
electrodes and sharpening one end of the needle blank so as to form a
sharpened tip and so that the first and second electrodes are exposed on said
tip such that exposed potions thereof are separated by a constant gap.
[0024] Preferably, the method includes sharpening the tip so as to have
a substantially conical or frustoconical shape. Preferably, the first and
second
electrodes are concentrically arranged and are separated by a concentric
insulation layer.
BRIEF DESCRIPTI~N GF THE DRAWINGS
[0025] Embodiments of the invention will be described in further detail,
by way of example only, with reference to the accompanying drawings, in
which:
(0026] Figure 1 is a side cross-sectional view of a tripolar concentric
needle according to an embodiment of the invention.
[0027, Figures 2A to 2G are side cross-sectional illustrations of steps in
a method of forming a tripolar concentric needle according to an embodiment
of the invention.
(0028] Figures 3A to 3G are side cross-sectional illustrations of
alternative method steps for forming a tripolar concentric needle.
'0029] Figure 4 is a side cross-sectional view of a tripolar concentric
needle according to an embodiment of the invention.
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[0030] Figures 5A and 5B illustrate a tripolar needle in plan and side
cross-sectional views, according to another embodiment of the invention.
[0031] Figures 6A and 6B illustrate a tripolar needle in plan side cross-
sectional views, according to yet another embodiment of the invention.
[0032] Figures 7A and 7B show a bipolar concentric needle having a
beveled tip in side cross-section and plan views.
[0033] Figure 8 shows a bipolar Concentric needle in side cross-
section, according to a further embodiment of the invention.
[0034] The drawings are not to scale.
DETAILED DESCRIPTION ~F THE INVENTION
[0035] Embodiments of the invention generally relate to needles having
more than one electrode and which are particularly suited to use in
electromyography (E!1lIG). Such embodiments of the invention relate to
methods of forming such needles.
[0036] Throughout the following description, like reference numerals
are used to indicate like components, features or functions. It should be
understood that features, components or functions described in relation to one
embodiment may also be employed in relation to any other embodiment,
except where it would be apparent to those skilled in the art that such a
combination would be unworkable.
(0037] The term "proximate" and "proximal" will be used herein to
indicate a direction away from the needle tip. The term "distal" will be used
herein to indicate a direction toward, or in the vicinity of, the needle tip.
j0038] Referring now to Figure 1, there is shown a side (longitudinal)
cross-sectional cylindrical tripolar needle 100. Needle 100 is called tripolar
because it has three conductors, namely a central conductor 105, a cannula
115 and an outer conductor 125. Central conductor 105, cannula 115 and
outer conductor 125 are electrically connected to an end cap (not shown
engaging a proximal end of the needle 100. in one embodiment, the electrical
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connections are made by respective electrical contacts 107, 117 and 127 by
means of an interterence fit with respective contacts in the end cap. Although
Figure 1 indicates that electrical contacts 107, 117 and 127 are made by wire
connection, this is less preferred than connection by interference fit.
(0039] Central conductor 105 is connected by a wire connection 107 so
as to be the active electrode, while cannula 115 is connected via wire
connection 117 so as to be the reference electrode. Outer conductor 125 is
connected via wire connection 127 so as to be a common or ground
electrode.
(0040] Central conductor 105 is separated from cannula 115 by an
inner insulator 110 surrounding the central conductor 105 in a cylindrical
manner. Cannula 115 is substantially cylindrical and is concentric with
central
conductor 105 and inner insulator 110. Outer insulator 120 is overlayed on
cannula 115, at least along shaft 140 of the needle away from tip 130. Outer
conductor 125 substantially cylindrical and is overlayed on outer insulator
120
and concentric therewith, while also being concentric with cannula 115 and
centre! conductor 105.
[0041] Needle 100 has an outer diameter C3 which is constant along the
shaft 140. At tip 130, which is substantially conically or frustoconically
shaped, the diameter of needle 100 focuses toward a point, although due to
physical limitations, the extremity of tip 130 can never truly be formed as a
point. At tip 130, central conductor 105, inner insulator 110 and cannula 115
have exposed frustoconical portions for contact with a desired part of anatomy
during EMG. At tip 130 and along the outer diameter of needle 100 proximally
adjacent tip 130, cannula 115 is the outermost exposed electrode. More
proximally of tip 130, cannula 115 reduces in diameter (via a short
frustoconical ramp 119 and outer conductor 125 becomes the outermost
exposed electrode. Outer insulator 120 completely separates cannula 115
from outer conductor 125 at all points along shaft 140 and tip 130.
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(0042] Although not shown in the drawings, needle 100 (and other
needle embodiments described herein) has a substantially circular lateral
cross-section.
(0043] The outer diar~neter of needle 100 ranges from 0.3mm to
0.65mm. Larger diameter needles are suited for deep anatomical structures
or muscles with large motor units. Small diameter needles are more suited for
muscles near the surface with small motor units, such as muscles in the
hands and face.
(0044] The central conductor 105 is formed of a wire core having a
diameter in the range of 0.025mm to 0.1 mm. The wire core is formed of
platinum, platinum-iridium or other biocompatible metals or alloys.
(0045] Cannula 115 has an outermost diameter of 0.3mm to 0.65mm
and a thickness in the range of 0.1 mm to 0.45mm. The cannula 115 is
formed of stainless steel (series 303, 304, 316 or 400), platinum, platinum-
iridium, silver or other biocompatible conductive metals or alloys. Cannula
115 may also be plated in gold or gold alloy. An intermediate diameter of
cannula 115 (i.e. where the cylindrical portion has been removed) is in the
range of 0.2mm to 0.55mm.
(0046] Outer conductor 125 has an outer diameter in the range of
0.3mm to 0.65mrr~, which is the same as cannula 115. The radial thickness of
outer conductor 125 is in the range of 0.251um to 0.4mm. Outer conductor
125 may be formed from stainless steel (series 303, 304, 316 or 400),
platinum, platinum-iridium, silver or other biocompatible conductive metals or
alloys. Outer conductor 125 may also be plated in gold or gold alloy.
(0047] Inner insulator 110, also called a core insulator, is preferably
made from epoxy, Teflon or other non-conductive biocompatible materials.
The radial thickness of inner insulator 110 is at least 0.075mm for effective
insulation.
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(0048] Outer insulator 120 is preferably formed of epoxy, Teflon or
other non-conductive biocompatible materials. The radial thickness of the
outer insulator 120 is at least 0.075mm for effective insulation.
[0049] Tip 130 of needle 100 may be formed as a pencil tip (i.e.
generally conical or frustroconical), such as is shown in Figure 1, or
alternatively as a beveled dip, such as is shown in Figure 4. The preferred
angle of the tip is about 15 degrees, but it may range from about 5 to 25
degrees. The distance from the tip point to the most distal part of the outer
conductor 125 is preferably in the range of 0.2mm to 10mm.
[0050] The outer diameter of cannula 115 adjacent tip 130 is the same
as that which would be used for a bipolar electrode needle. Thus, according
to a preferred embodiment of the invention, a tripolar electrode needle can be
obtained without increasing the diameter of the needle.
j0051] Advantageausly, tripolar embodiments of the invention allow a
common electrode to be located in close proximity to the active and reference
electrodes. Further advantageously, the common electrode does not need to
be placed on the skin as a separate, time-consuming action because it can be
inserted along with the active and reference electrodes as part of the needle.
[0052] Thus, tripolar embodiments of the invention can achieve better
signal quality by having the common electrode close to the active and
reference electrodes, while enabling a more time-efficient EMG set up
procedure. This is achieved without increasing the diameter of the needle
beyond that of a standard bipolar needle and therefore without increasing the
pain inflicted on the patient.
[0053) Referring now to Figures 2A to 2G, there are shown side cross-
sections of a needle blank at a number of steps in the formation of needle
100. These steps are part of a method of forming a tripolar needle according
to one preferred ernbodiment of the invention.
(00x4] Referring first to Figure 2A, there is shown a needle blank 200,
having the cannula 115 concentrically arranged around inner insulator 110
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and central conductor 105. Concentric needle blanks such as needle blank
200 are commercially available, for example from Excel-tech Ltd. Of Oakville,
Ontario, Canada.
[0055] In Figure 2~, a generally cylindrical portion of the cannula 115 is
removed along shaft 140. The needle blank with the cylindrical portion
removed is designated by reference numeral 205. A minimum radial thickness
of about 75.25p.m is removed from the cannula 115, which is the minimum
thickness of the outer insulator 120 and outer conductor 125 combined. The
generally cylindrical cannula portion is removed so as to leave a generally
frustoconical ramp 119 between the portion of the cannula having been
reduced in diameter and the portion of the cannula maintaining its original
diameter. The generally cylindrical portion is cut away removed by, for
example, etching, grinding or another machining process of suitable precision.
[0056] In Figure 2C, the needle blank is shown with an added insulation
layer to form outer insulator layer 120. This form of the needle blank is
designated by reference numeral 210. Outer insulator 120 is coated onto
needle blank 205 so as to cover substantially the whole length thereof. Along
shaft 140, the outer insulator 120 is preferably formed around the outside of
cannula 115 so as to have a substantially constant radial thickness less than
the outermost diameter of the cannula 115. This allows outer conductor 125
to be formed around outer insulator 120 so as to have an outer diameter not
greater than that of the outermost diameter of cannula 115.
[0057] Outer insulator 120 is formed by a suitable coating procedure
and is allowed to set or cure after it is formed. As an optional step, in
order to
ensure that the outer insulator 120 is of constant diameter along shaft 140,
needle blank 210 may be machined so as to cut away any excess insulator
material along shaft 140.
[0058] Outer insulator 120 is formed so as to cover ramp 119. Outer
insulator 120 is therefore formed more thickly adjacent ramp 119 and
immediately proximally thereof. Outer insulator 120 adjacent ramp 119
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serves to separate cannula 115 at its outermost diameter from outer
conductor 125 along the outside of needle 100.
[0059] In Figure 2~, outer conductor 125 is applied to needle blank
210, resulting in a form of the needle blank designated by reference 215.
Outer conductor 125 is formed by coating, plating, depositing or other
suitable
method of forming a layer of conducted material around insulation material.
[0060] Outer conductor 125 may be formed around outer insulator 120
with greater thickness than necessary, as any excess material can be cut
away. The radial thickness of the outer conductor 125 formed along shaft 140
must be sufficient to bring the outer diameter of outer conductor 125 out to
the
same diameter as the outermost diameter of cannula 115.
[0061] In Figure 2~, needle blank 215 is cut, machined, etched or
otherwise reduced in diameter so as to have a substantially uniform outer
diameter along the length of the needle blank, designated by reference
numeral 220. In this way, excess conductive and insulative material formed at
210 and 215 are removed so as to leave an outer conductor 125 of
substantially constant radial thickness along the length of shaft 140 and
separated from cannula 115 by outer insulator 120. Optionally, if sufficient
thickness of cannula 115 and outer conductor 125 permit, the outer diameter
along the shaft and toward the tip (including the outermost radial part of
cannula 115) may be reduced during this cutting step by a thickness of, for
example, 0.01 mm to 0.1 mm.
[0062] In Figure 2F, tip 130 is formed so as to enable better penetration
of the skin, producing a needle blank designated by reference numeral 225.
The tip 130 may be formed by a suitable sharpening method, such as cutting
or grinding, so as to provide a tip having an acute angle of between 5 and 25
degrees, and more preferably 15 degrees. Tip 130 is preferably formed so as
to be substantially conical or frustoconical, thus resembling a pencil tip,
but
may be alternatively formed so as to have a beveled edge (see Figure 4, for
example).
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[0063] According to one embodiment, only central conductor 105, inner
insulator 110 and cannula 115 are exposed at tip 130. In an alternative
embodiment, tip 130 may be cut so as to also expose outer insulator 120 and
outer conductor 125 as part of the tip, rather than only along shaft 140.
(0064] in Figure 2G, the needle blank formed at 225 is cut or ground at
its proximal end so as to expose centre! conductor 105 and cannula 115.
Electrical connections 107, 117 and 127 are formed between central
conductor 105, cannuia 115 and outer conductor 125, respectively, and the
end cap. The end cap preferably forms the electrical connections 107, 117
and 127 by forming a mechanical interference fit with spring-loaded contacts
within the end cap. The end cap can then be used to convey electrical signals
picked up by the electrodes in the needle to the EMG equipment. The needle
shown in Figure 2G is designated by reference numeral 230, which
corresponds to the final step in forming needle 100.
[0065] In an alternative method of forming needle 100, needle blank
designated by reference numerals 210, 215 and 220 may be formed
according to alternative steps, as described hereinafter in relation to
Figures
3A to 3C.
[0066] With reference now to Figure 3A, instead of forming outer
conductor 125 by coating, plating or depositing, a conductive sleeve 325 may
be used to form outer conductor 125. After the portion of cannula 115 is
removed, conductive sleeve 325 is placed around the outside of the reduced
diameter portion of cannula 115, along the length of shaft 140. Conductive
sleeve 325 is positioned so that its distal end is positioned proximally of
ramp
119. This form of needle blank is designated by reference numeral 310.
[0067] As shown in Figure 3B, a liquid insulator is injected in between
conductive sleeve 325 and cannula 115 of needle blank 310. The liquid
insulator is preferably epoxy or Teflon, but may be another form of suitable
curable material. The outer insulator 120 thus formed by injection is then
allowed to set or cure, which fixes the conductive sleeve 325 in place
relative
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to needle blank 310. This injection and curing step results in a needle blank
designated by reference numeral 315.
(0068, As shown in relation to Figure 3~, following the injection of outer
insulator material 120 after curing thereof, excess insulator material and
part
of conductive sleeve 325 are removed, for exarrbple by machining it, cutting
or
etching, and the needle blank is then polished to a desired finish to form
needle blank 320. The resulting needle blank 320 is of substantially uniform
outer diameter and is analogous to needle blank 220.
(0069] As an alternative, rather than injecting the insulator fluid
between conductive sleeve 325 and cannula 115, insulation material may be
formed around the needle blank according to previously described step 210
and conductive sleeve 325 is then slid into position over the insulation layer
while the liquid insulator is sufficiently soft and fluid.
(0070] In a further alternative, an outer conductive sleeve may be
heated to expand and then placed over a solid insulator and allowed to cool
and contract. A final cutting step can be used to reduce the outer diameter
and to remove excess material.
(0071] As an additional step applicable to the above described methods
of forming a needle, prior to final formation of needle 100, it is preferred
to
polish the needle so as to produce a smooth outer surface.
(0072] Referring now to Figure 4, there is shown a needle 400 of
similar construction to needle 100, except that it is formed to have a beveled
tip 430. Beveled tip 430 is formed by grinding or cutting, for example.
Features and functions of needle 400 are otherwise the same as those
described in relation to Figures 1, 2A to 2G and 3A to 3C.
(0073] Referring now to Figures 5A and 5B, there are shown plan and
side cross-sectional views of a further tripolar needle embodiment, designated
by reference numeral 500. Needle 500 is substantially similar to needle 100
in form and function, except that it is made with a different internal
structure.
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(0074, Needle 500 comprises a central conductor 505, which acts as
an active electrode, an intermediate conductor 515, which acts as a reference
electrode, and an outer conductor 525, which acts as a common or ground
electrode. Insulator material 510 separates central conductor 505 from the
intermediate and outer conductors 515, 525. C3uter conductor 525 has an
outer diameter which is the same as the outermost diameter of intermediate
conductor 515. ~uter conductor 525 extends generally proximally of tip
portion 530 and intermediate conductor 515.
(0075] Central conductor 505, insulator 510 and intermediate conductor
515 are exposed at a pencil tip shaped tip portion 530. Central conductor 505
comprises an enlarged head portion towards tip 530, which is wire bonded to
a wire conductor extending within shaft 540 back to a proximal end cap (not
shown). Intermediate conductor 515 also has an enlarged head portion at tip
530, extending roughly cylindrically and frustoconically toward the pencil tip
shaped end portion 530. Intermediate conductor 515 is also wire bonded to a
wire conductor extending proximally along shaft 540 to the end cap.
[0076, Referring now to Figures 6A and 6B, a further tripoiar needle
embodiment is shown in plan and side cross-section, respectively. Needle
600 is substantially similar to needle 500, except that it has a beveled tip
630
instead of the pencil shaped tip 530. Reference indicators used in relation to
Figures 6A and 6~ correspond generally to those parts shown and described
in relation to Figures 5A and 5~, where the last two numbers of the reference
numerals are the same. For example, outer conductor 525 corresponds to
and has substantially the same form and function of, outer conductor 525.
(0~77~ Referring now to Figures 7A and 7~, there is shown a concentric
bipolar needle 700 having a beveled tip 730. Needle 700 has a central
conductor 705 and an outer conductor 715 separated by insulator 710.
Needle 700 presents an elliptical face at its tip, where the exposed end
surface of central conductor 705 is located in the center of the exposed face.
Insulator 710 separates central conductor 705 from outer conductor 715 by a
variable distance ~ according to the position on the exposed elliptical face.
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The distance X is largest in the direction of longitudinal extension of the
needle 700, while it is smallest in the lateral direction, as is evident in
Figure
7B. The exposed elliptical face can be used by a medical practitioner
conducting the EIVIG to directionally target a signal source.
[0078] Referring now t~ Figure 8, a further embodiment of the invention
is shown in side cross-section as needle 800. Needle 800 has a central
conductor 805 and an outer conductor 815 separated by an insulator 810. A
tip 830 of needle 800 is formed so as to have the shape of a pencil tip,
rather
than a beveled tip. Forming the tip 830 of bipolar concentric needle 800 as a
pencil tip allows for a distance Y between central conductor 805 and outer
conductor 815 to be substantially constant around the tip. The preferred
dimensions and materials for needle 800 are the same as for needle 100,
where outer diameter 815 equates to cannula 115.
[0079, Needle 800 provides a better signal quality than needle 700,
resulting from the constant distance between the active and reference
electrodes. This distance can be sized to match the typical motor unit being
probed, with different tips for different rnuscies. The constant distance
between electrodes also prevents electrical breakdown due to an inadequate
insulation gap that can occur with beveled tip geometries.
[0080, Needle 800 also provides enhanced patient comfort as the
gauge of the needle can be made smaller than conventional concentric
needle designs. This is because the same insulation gap as that of a
standard beveled tip concentric needle can be achieved with a smaller
diameter using a pencil tip. The insulation gap can be further increased by
making the angle of the pencil tip more acute, say in the order of 10 degrees.
[0081] While the present invention has been described with reference
to what are presently considered to be the preferred examples, it is to be
understood that the invention is not limited to the disclosed examples. To the
contrary, the invention is intended to cover various modifications and
equivalent arrangements included within the spirit and scope of the invention.
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