An endoscopic needle device includes an outer sheath, an elongate shaft extending through the sheath, a needle rigidly attached to the distal end of the shaft, and a handle assembly having a housing coupled to the proximal end of the sheath and having a syringe port in fluid communication with the sheath and a knob rotatably coupled to the housing. Rotation of the knob relative to the housing causes rotation of the shaft relative to the sheath. The needle and the distal end of the sheath are mated by a threaded connection. As such, rotation of the knob relative to the housing causes precise longitudinal movement and extension of the needle relative to the distal end of the sheath. A set of intermeshing gears are provided between the knob and shaft which function to permit at most one rotation of the knob to cause complete extension and/or retraction of the needle. Furthermore, assemblies are provided with permit the shaft to accommodate movement of the needle relative to the sheath. Moreover, the position of the knob relative to the housing provides an indication of the extension of the needle. As such, the injection needle device of the invention permits controllable and calibrated rotation of the needle to within a few degrees, such that the needle device can be easily, reliably, and precisely operated to advance the needle.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates broadly to endoscopic instruments. More
 particularly, this invention relates to endoscopic injection needle
 devices.
 2. State of the Art
 An endoscopic injection needle device is inserted through a lumen of a
 flexible endoscope to inject fluids under endoscopic visualization in body
 structures such as the esophagus, the stomach, and the colon. For example,
 during a colonic polypectomy, it is customary to inject saline solution
 into the tissue surrounding and underlying a polyp in order to raise the
 polyp to facilitate excision of the polyp by means of an endoscopic
 forceps or snares. Visible dyes and radiological contrast dyes are
 sometimes injected to mark the location of areas explored endoscopically
 so that the structures can be located during subsequent procedures.
 Additionally, sclerosing agents are sometimes injected into vascular
 structures, such as esophageal varicoceles, in order to cause clotting and
 to necrose the tissue so that it can be resorbed by the body.
 Typically, an injection needle device consists of a flexible inner tubing
 (or fluid conduit), usually made of polytetrafluoroethylene (PTFE),
 surrounded by a loose-fitting outer jacket made of PTFE, fluorinated
 ethylene propylene (FEP), or similar flexible plastic, a handle assembly
 at the proximal ends of the inner tubing and outer jacket for relative
 axial movement thereof, and a needle attached to the distal end of the
 inner tubing.
 In practice, a physician grips the outer jacket of the injection needle
 device with one hand to introduce it through a sealing port on the
 endoscope handle which communicates with the working channel of the
 endoscope and to position the distal end of the device proximate the
 desired tissue at the distal end of the endoscope. With his or her other
 hand, the physician holds the proximal handle of the endoscope so that the
 steering knobs on the endoscope handle can be manipulated while viewing
 the endoscopic image. The handle assembly of the endoscopic needle device
 is held and manipulated by an assistant, according to the oral commands of
 the physician. The assistant moves one component of the handle assembly
 relative to the other to move the inner tubing axially relative to the
 outer jacket, thus retracting the needle into the outer jacket or
 extending it beyond the distal tip of the outer jacket. Once the needle is
 in position, the assistant then injects a fluid or medicament into the
 tissue by means of a syringe attached to the handle assembly of the
 device.
 The amount of penetration of the needle into the tissue is not easily
 controlled by either the physician or the assistant. The depth of
 penetration of the needle is limited only by the fact that the fluid
 conduit (or the connector joining the needle point to the fluid conduit)
 which is larger in diameter than the needle, abuts the tissue. In an
 alternative procedural method, the physician pushes the jacket up against
 the tissue, and then the physician orders the assistant to fully advance
 the needle. In this manner, there is no visualization or degree of control
 to the penetration of the needle point, except as limited by the abutment
 of the fluid conduit or connector against the tissue. If the physician
 determines that a different amount of needle penetration is desired,
 another device with a needle point of a different length must be used.
 While it is customary for a physician to standardize his practice with a
 needle of a certain penetration length, it sometimes is necessary to
 inject more superficially, to reduce the possibility of penetrating the
 tissue structure, or more deeply, to reach a plane of dissection to
 separate layers of tissue. Therefore, it is necessary to stock several
 injection needle devices in each gastroenterology suite, each device
 having a needle with a different length to accommodate the needs of the
 physician.
 A few prior art devices have been built which allow the assistant to
 control the depth of needle projection beyond the distal end of the
 jacket, but these devices are imprecise and awkward. For example, the
 devices described in U.S. Pat. No. 5,380,292 to Wilson and U.S. Pat. No.
 4,763,667 to Manzo attempt to achieve a measure of adjustability of the
 needle projection by utilizing an adjustable stop on the handle assembly
 of the device. The Wilson and Manzo devices do not have a calibrated
 control mechanism, and there is no way for the assistant to accurately
 adjust the depth of needle penetration while the device is in place in the
 endoscope, because such would require visualization of the needle point
 and measurement of its projection beyond the distal end of the jacket
 while turning an adjustment nut. Rather, the Wilson and Manzo devices
 simply provide a manner by which the device can be prepared prior to use
 for a specific amount of needle projection. Unfortunately, even the
 adjustable stop is of limited value, because the design of these prior art
 devices is such that the length of needle point projection beyond the
 jacket is highly variable despite the stop. In fact, the position of the
 needle is strongly influenced by the shape of the endoscope and by forces
 acting on the needle point. Depending on the degree to which the endoscope
 is flexed to negotiate the anatomy of the patient, the length of needle
 projection of most prior art devices is variable because of the various
 possible positions of the fluid conduit tubing within the loose-fitting
 outer jacket of the device. Thus, as the device is flexed, the needle
 point moves relative to the distal end of the jacket. Also, such designs
 which use a flexible plastic tube for the fluid conduit, are not amenable
 to precise control of the needle projection, because their needles will
 retract to some degree, typically a few millimeters, when forced against
 tissue. Thus, these devices do not teach a practicable means of
 controlling the length of needle projection while the device is being
 used.
 U.S. Pat. No. 5,766,184 to Matsuno et al. describes another needle device
 having an outer tubular sheath, an inner tubular member extending through
 the outer tubular sheath and longitudinally and axially rotatably movable
 relative thereto, a shaft extending through the inner tubular member and
 coupled to the needle, a needle at the distal end of the inner tubular
 member, and a handle assembly including a knob which permits axial
 rotation of the shaft, and therefore the inner tubular member and needle,
 relative to the sheath. The needle and the distal end of the outer sheath
 are threadably connected. This threaded connection permits helical
 rotation of the inner tubular member relative to the outer tubular sheath
 to cause precise longitudinal movement of the needle relative to the
 distal end of the outer tubular sheath. Fluid is injectable through the
 inner tubular member and the needle into the patient. However, the device
 has severe drawbacks. First, it is generally desirable that the pitch of
 the threads be sufficiently small to permit the fine and precise
 adjustment of the extension of the needle, e.g., movement of the needle to
 within a half millimeter. Such fine adjustment requires that the pitch of
 the thread in the connection preferably be no more than a half millimeter.
 Yet, this requires that the inner tubular member be rotated a very large
 number of times relative to the outer tubular member in order to move the
 needle the required distance. For example, at a pitch of a quarter
 millimeter, the inner tubular member and outer tubular sheath would need
 to be completely rotated thirteen times relative to each other in order to
 effectuate a 6.5 millimeter movement of the needle. Such device operation
 is impractical for two reasons. First, it is impractical for the physician
 or assistant to keep count of how many times he or she has rotated the
 knob which causes the inner tubular member to rotate relative to the outer
 tubular member. However, keeping count is required as there is no other
 means by which to determine how far the needle has been extended. As such,
 absent reliance on the physician's or assistant's memory as to how may
 times the inner tubular member and outer tubular sheath have been rotated
 relative to each other, it is not possible to determine from the proximal
 end of the instrument the extension of the needle from the distal end of
 the instrument. Second, even if the physician or assistant could
 accurately keep count of the number of rotations, such repetitive
 rotational movement is uncomfortable, resulting in hand strain. Therefore,
 this needle device is undesirable to both the physician and the assistant.
 Second, the patent fails to adequately describe a handle assembly which
 can correctly accommodate axial movement of the shaft and inner tubular
 member relative to the outer sheath as the needle is helically advanced
 and retracted.
 SUMMARY OF THE INVENTION
 It is therefore an object of the invention to provide an endoscopic needle
 device having a proximal handle assembly which accurately indicates the
 extension of the needle from the distal end of the device.
 It is another object of the invention to provide an endoscopic needle
 device which requires rotation of a control member one turn or less
 relative to the handle assembly in order to move the needle from a
 retracted position into a fully extended position.
 It is a further object of the invention to provide an endoscopic needle
 device which may be conveniently and comfortably operated.
 It is also an object of the invention to provide an endoscopic needle
 device in which the needle is precisely adjustable to deliver different
 depths of penetration of the needle point while the device is in use.
 It is an additional object of the invention to provide an endoscopic needle
 device which precisely controls the position of the needle relative to the
 distal end of the jacket.
 It is yet another object of the invention to provide an endoscopic needle
 device in which extension of the needle is not affected by such factors as
 compressibility of the tubular components and relative slack of coaxial
 push-pull elements.
 It is yet a further object of the invention to provide an endoscopic needle
 device in which the needle will not inadvertently retract even when
 subject to substantial force placed on the tip of the needle point.
 In accord with these objects, which will be discussed in detail below, an
 endoscopic needle device is provided which includes an outer sheath, an
 elongate shaft extending through the sheath, and a needle rigidly attached
 to the distal end of the shaft. According to one embodiment of the
 invention, the needle includes a proximal opening such that the hollow of
 the needle is in fluid communication with the sheath. A substantially
 fluid-tight seal is provided between the needle and the sheath. The device
 further includes a handle assembly having a housing coupled to the
 proximal end of the sheath and having a port and channel in fluid
 communication with the sheath, such that a syringe may be coupled to the
 port and operated to inject a fluid (injectate) which travels through the
 channel, sheath and needle. The handle assembly also includes a knob
 rotatably coupled to the housing and coupled to the proximal end of the
 shaft. Rotation of the knob relative to the housing causes rotation of the
 shaft, and therefore the needle, relative to the sheath. The needle and
 the distal end of the sheath are mated by a threaded connection. As such,
 rotation of the knob relative to the housing causes precise helical
 movement and extension (or retraction) of the needle relative to the
 distal end of the sheath.
 According to another embodiment of the invention, the needle is coupled to
 both the distal end of the shaft and an inner tubular member extending
 through the sheath. The needle is in fluid communication with the inner
 tubular member. The handle assembly has a housing coupled to the proximal
 end of the sheath and a knob rotatably coupled to the housing and coupled
 to the proximal end of the shaft. The housing also has a port and a
 channel in fluid communication with the inner tubular member, such that a
 syringe may be coupled to the port and operated to inject a fluid which
 travels through the channel, the inner tubular member and the needle.
 Rotation of the knob relative to the housing causes rotation of the shaft,
 and therefore the inner tubular member and needle, relative to the sheath,
 and results in precise helical movement and axial extension (or
 retraction) of the needle relative to the distal end of the sheath.
 In accord with a preferred aspect of the invention, a set of intermeshing
 gears is provided between the knob and shaft and function to permit at
 most one rotation of the knob to cause complete extension and/or
 retraction of the needle. Furthermore, assemblies are provided with permit
 the shaft in the first embodiment, and shaft and inner tubular member in
 the second embodiment, to accommodate movement of the needle relative to
 the sheath. Moreover, in each embodiment, the position of the knob
 relative to the housing provides an indication of the extension of the
 needle. As such, the injection needle device of the invention permits
 controllable and calibrated rotation of the needle to within a few
 degrees, such that the needle device can be easily, reliably, and
 precisely operated to advance the needle.
 Additional objects and advantages of the invention will become apparent to
 those skilled in the art upon reference to the detailed description taken
 in conjunction with the provided figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Turning now to FIGS. 1 and 2, an endoscopic injection needle device 10
 includes a flexible tubular outer sheath 12, an elongate flexible shaft 14
 extending through the sheath 12, and a needle 16 attached to a distal end
 17 of the shaft 14. The needle 16 includes a proximal entryway 18 such
 that a bore 19 of the needle is in fluid communication with the sheath 12.
 A handle assembly 20 includes a housing 22 provided at the proximal ends
 24, 26 of the sheath 12 and shaft 14. The proximal end 24 of the sheath 12
 is coupled to the housing 22, preferably with a flare nut connection 28.
 The handle assembly 20 also includes a control knob 36 which is rotatably
 coupled to the housing 22. As will be discussed in detail hereinafter with
 respect to FIG. 3, rotation of the control knob 36 relative to the housing
 22 causes rotation of the shaft 14 relative to the sheath 12. The housing
 22 includes a channel or tube 30 having a syringe port, e.g., a female
 luer connection, in fluid communication with the sheath, such that a
 syringe 34 may be coupled to the port and operated to inject an injectate
 through the channel 30 and the sheath 12 (around shaft 14) and into the
 needle 16. The shaft 14 extends through the proximal end 24 of the sheath
 12, into the channel 30, and exits through a hole or port 35 in the
 channel 30 and is coupled to the control knob 36. A substantially
 fluid-tight seal 37 is provided at the hole 35 to prevent fluid leakage
 therethrough.
 The sheath 12 is preferably a length of PTFE tubing, and provides
 flexibility, sufficient strength to resist internal fluid pressure, and
 inertness to all known injectates. By way of example, the sheath 12 may be
 extruded PTFE tubing with an outside diameter of 0.078 inches and an inner
 diameter of 0.055 inches.
 The shaft 14 is preferably a high strength, straightened (camber-free)
 stainless steel wire which extends continuously from the needle 16 to the
 handle assembly 20. The camber-free shaft 14 has a high elastic limit, and
 may be bent with the needle device through a tortuous path without
 permanent deformation. Moreover, as the shaft 14 is free of camber,
 rotation thereof precisely rotates the needle. By way of example, the
 shaft 14 may be 304V spring-temper wire of 325,000 psi UTS and 0.017 inch
 diameter.
 Referring to FIG. 2, the needle 16 is preferably made from stainless steel
 tubing, preferably 25 gage, and preferably has a standard double-bevel
 needle point grind at its distal end 38. The proximal end of the needle is
 cut away to form a tab 39, which is attached to the distal end 17 of the
 shaft, and the entryway 18 allows the injectate fluid to enter the needle
 bore 19. Alternatively, the needle may be attached to the shaft with a
 crimp or by bonding, so long as an entryway is provided for fluid passage
 into the needle bore 19. If desired, the entryway may constitute a series
 of lateral holes in the needle.
 Still referring to FIG. 2, the needle 16 has a threaded or
 helically-splined outer sleeve (needle sleeve) 40 crimped or bonded onto
 it, which in turn is engaged inside a threaded inner sleeve (sheath
 sleeve) 42 attached to or integral with the distal end 44 of the flexible
 tubular sheath 12. The needle 16 and distal end 44 of the sheath are
 thereby threadably connected. As the needle 16 is rotated, the needle
 sleeve 40 is induced to move helically through the sheath sleeve 42, so
 the needle 16 is advanced out of and retracted back into the distal end 44
 of the sheath 12. The sheath sleeve 42 is preferably provided with an
 inwardly-directed lip 45 which functions as a stop to prevent retraction
 of the needle 16 beyond a maximum desirable amount. An end cap 46 is
 preferably provided at the distal end 44 of the sheath and functions as a
 stop to prevent extension of the needle beyond a maximum desirable amount.
 The threaded connection of the needle and sheath are also preferably
 provided with an O-ring 48 (or other resilient seal member) and a seal
 locking member 50 which prevents migration of the O-ring 48 along the
 needle 16. The O-ring 48 and seal locking member 50 together substantially
 prevent fluid traveling through the sheath 12 from exiting the distal end
 44 of the sheath other than through the bore 19 of the needle 16.
 Alternatively or additionally, a fluid tight seal can be provided at the
 end cap 46 or proximal the sheath sleeve 42.
 Referring to FIGS. 3 and 4, the handle assembly 20 includes a "rotational
 step-up" means 60 so that the operator of the device is not required to
 rotate the control knob 36 more than one turn in order to extend or
 retract the needle a desired distance. For example, the threaded needle
 and sheath sleeves 40, 42 at the needle 16 and distal end 44 of the
 sheath, which generate the longitudinal movement of the needle in response
 to rotation of the shaft 14, may have a pitch in the range of 0.1 to 1.0
 millimeter per turn, and preferably about 0.25 millimeters. Most
 physicians require needle extensions of eight millimeters or less, and it
 is desirable to have the needle retracted about two millimeters when not
 in use. As such, a total range of motion of at least ten millimeters is
 preferred. Thus, for threads with a 0.25 millimeter pitch, movement of the
 needle from a retracted position to that of greatest extension would
 require a total of forty turns. As discussed above in the background
 section, this is undesirable. According to a preferred aspect of the
 invention, the operator is only required to turn the control knob 36 of
 the handle assembly 20 at most one full turn, and preferably less than one
 full turn, to achieve the full range of motion (i.e., from a retracted
 position to a fully extended position). This aspect is achieved by the use
 of a rotational step-up means, preferably providing a rotational step-up
 ratio of about 1:50.
 According to a preferred embodiment, the rotational step-up means 60 is a
 gear box of either spur-gear or planetary design. For example, a spur-gear
 box consisting of three increasing stages (1:4, 1:4, 1:3) provides a 1:48
 ratio. According to the example, the control knob 36 includes a wheel 62
 of forty teeth driving a change gear 64 with a pinion 66 of ten teeth and
 an output wheel 68 of forty teeth. The output wheel 68 of the change gear
 64 drives a second change gear 70 with a ten tooth pinion 72 and thirty
 tooth wheel 74. The thirty tooth wheel 74 of the second change gear 70
 drives a pinion 76 of ten teeth which includes a tubular output end 78
 which is preferably coupled in an axially compliant manner, as described
 below, to the proximal end 26 of the flexible shaft 14. Thus, whenever the
 control knob 36 is rotated one turn, the flexible shaft 14 is rotated
 forty eight turns.
 For a needle sleeve 40 having threads with 0.25 millimeter pitch, one full
 turn of the control knob 36 results in the needle 16 advancing, or
 retracting, twelve millimeters (forty eight turns.times.0.25 mm/turn),
 which provides more than the required minimum axial movement. For each
 millimeter of needle motion, the control knob 36 is turned thirty degrees
 (360 degrees/turn divided by 12 mm/turn). Thus, the control knob 36 is
 preferably calibrated in millimeter increments from -2 to 10, with the
 increments provided as indicia 80 on the control knob 36, each one
 millimeter increment preferably being thirty degrees from the next. An
 index mark 82 is provided on the housing 22 against which the incremental
 indicia 80 on the control knob 36 can be aligned or otherwise related to
 determine the exact position of the needle 16.
 Alternatively, a faster pitch thread may be used on the needle sleeve 40.
 For example, using a one millimeter pitch, the shaft 14 need only be
 rotated ten times to achieve the desired motion. Thus, a 1:12 step-up
 ratio would suffice, which may be achieved with a relatively simpler
 gearbox: for example, two stages of 1:3 and 1:4. Even longer pitches could
 be used, but at pitches substantially longer than one millimeter the
 position of the needle 16 could be influenced by forces acting on the
 needle tip 38; that is, axial forces on the needle tip may cause the
 needle 16 to rotate and retract. Furthermore, a long-pitch thread results
 in lower mechanical advantage in the system, so that the advancement of
 the needle is not as reliable when the needle must be forced into tissue.
 This problem results from the very high torque that is required to
 generate penetration force at the needle, resulting in "wind-up" of the
 shaft.
 As another alternative, shorter pitch threads, e.g, 0.1 millimeters, may be
 used, but such very fine threads are more fragile than the preferred
 moderate pitch threads, and also require greater precision in manufacture
 and assembly. Also, with shorter pitch threads, the required step-up means
 must have a very high ratio (e.g., 1:100), resulting in increased backlash
 and friction, which would in turn adversely affect the precision of needle
 advancement.
 Thus, it can be seen that a moderate pitch thread, e.g., having a pitch of
 0.25 mm, is most advantageous since such a thread permits the use of a
 practicable gear box, yet generates sufficient penetration force at the
 needle tip.
 Turning to FIGS. 5 and 6, regardless of which needle pitch is used, because
 rotation of the shaft causes the needle point to be translated proximally
 and distally, and because the control knob 36 is fixed axially to the
 housing 22, the proximal end 26 of the flexible shaft 14 is coupled to the
 output end 78 of pinion 76 in a manner which allows for the shaft to
 accommodate axial movement of the shaft. A preferred manner to achieve
 this axially-compliant coupling is with a sliding joint assembly 80. For
 the sliding joint assembly 80, the tubular output end 78 of the pinion 76
 includes a non-circular bore 82, e.g., square or hexagonal in
 cross-sectional shape, and the proximal end 26 of the flexible shaft 14 is
 provided with an outer sleeve 83 defining a non-circular key 84, adapted
 to be received into and mate with the non-circular bore 82. Since only ten
 millimeters of longitudinal motion need be accommodated by the sliding
 joint assembly 80, a one millimeter square key approximately four
 millimeters in length can be received into a tubular output end 78 having
 a bore 82 approximately fifteen millimeters in length and of a square
 cross-section only slightly larger in size than the cross-sectional size
 of the key 84. The fifteen millimeter length of the bore accommodates
 greater manufacturing tolerances. As such, when the needle 16 is moved
 axially at the distal end of the device 10, the proximal end 26 of the
 flexible shaft 14 is permitted to slide within the bore 82 of the tubular
 output end 78 of the output pinion 76 to accommodate that axial movement.
 Therefore, the sliding joint assembly 80 maintains the ability to rotate
 the shaft 14 relative to the housing 22 and the sheath 12, even when the
 shaft 14 is moved axially relative to the housing 22 and sheath 12.
 As a result, a single operator of the device, whether physician or
 assistant, can rotate the control knob 36 relative to the housing 22 and
 cause precise longitudinal movement and extension of the needle 16
 relative to the distal end 44 of the sheath 12. The distance of
 longitudinal movement is indicated at the handle assembly 20 by the
 indicia 80, 82. The endoscopic injection needle device 10 precisely
 controls advancement of a needle to within a small fraction of a
 millimeter. In addition, the same operator can also inject fluid from
 within the syringe through the sheath and needle and into the tissue where
 the extended needle is located.
 Referring now to FIG. 7, a second embodiment of an endoscopic needle
 injection device, substantially similar to the first embodiment (with like
 parts having numbers incremented by 100) is shown. The device 110 includes
 a sheath 112, an inner tubular member 113 having a needle 116 at the
 distal end thereof and in fluid communication therewith, a flexible shaft
 114 extending through the inner tubular member 113 and rigidly coupled to
 the needle 116, e.g., via a weld 117, and a handle assembly 120 for
 rotating the shaft 114 relative to the sheath 112. A threaded connection
 comprising a needle sleeve 140 about the needle 116, and a threaded cap
 142 at the distal end of the sheath 112 is provided to permit helical
 rotation of the needle 116 relative to the sheath 112 to result in axial
 movement of the needle relative to the sheath. Rotation of the shaft 114
 relative to the sheath causes rotation of the inner tubular member 113 and
 needle 116 relative to the sheath.
 The handle assembly 120 includes a housing 122, and the proximal end 124 of
 the sheath 112 is coupled to the distal end of the housing with a flare
 nut connection 128. The housing 122 includes a T-shaped channel 130 having
 a first portion 131 aligned with the sheath and having a relatively
 enlarged diameter cavity 133 at the distal end of the housing and a second
 portion 135 terminating in a syringe port 132; i.e., a female luer lock.
 The proximal end 137 of the inner tubular member 113 is optionally
 provided with a ferrule 139 which is sized to axially slide and rotate
 within the cavity 133 (and provide a fluid seal), but yet is unable to
 exit the cavity due to stops 143 and 145. The ferrule 139 is preferably
 able to slide ten to twelve millimeters; i.e., a distance permitting the
 entire desirable range of axial movement of the needle. The proximal end
 126 of the flexible shaft 114 extends through the first portion 131 of the
 bore 130 and through a substantially fluid-tight seal 141 to a sliding
 assembly 180, substantially as described above with respect to sliding
 assembly 80 in the first embodiment. The sliding assembly is further
 coupled to a gear assembly 160, substantially as described above with
 respect to gear assembly 60 in the first embodiment. The gear assembly 60
 is coupled to a control knob 136.
 In use, when the control knob 136 is rotated relative to the housing 122,
 the gear assembly 160 operates, as a described above, to step-up the
 rotation of shaft 114 rotation. As the shaft 114 rotates, the needle
 sleeve 140 on the needle 116 is rotated relative to the threaded end cap
 142 at the distal end of the sheath 112, and the needle helically advances
 (or helically retracts when the knob is rotated in an opposite direction).
 A syringe (not shown) coupled to the syringe port 132 may be operated to
 inject fluid through the channel 130, the inner tubular member 113 and
 needle 116, without the use of substantially fluid-tight seals at the
 distal end of the instrument 110.
 Turning to FIGS. 8 and 9, the handle assembly of either embodiment of the
 endoscopic needle injection device may be provided with a step-up gear
 assembly which translates linear motion of a control member into
 rotational movement of the shaft. As such, the handle assembly 220
 includes a housing 222 and a control member 236 slidable relative to the
 housing. The control member 236 includes an upper finger engageable
 portion 286 engageable by a finger of the operator of the device,
 preferably provided with ridges 288 or another high friction surface, and
 has a rack portion 290 extending partially through a slot 291 in the
 housing into the interior of the housing. If desired, the control member
 236 can also include an indicator 280 which can be aligned relative to
 graduated indicia 282 on the housing 222 to indicate the position of the
 needle tip relative to the distal end of the sheath, as effectuated by
 movement of the control member 236 relative to the housing 222 described
 below. A gear assembly 260 includes a helically threaded pinion 262 which
 is engaged by the rack portion 290 such that longitudinal movement of the
 control member 236 relative to the housing 222 causes the rack portion to
 move against the thread of the pinion 262 and cause rotation of the
 pinion. The pinion 262 has an output wheel 263 which engages a pinion 266
 of change gear 264. The change gear 264 has a gear-toothed output wheel
 266 which engages a pinion 272 of an output gear 270, and the output gear
 270 has a output wheel 274 which engages a pinion 276 coupled to an
 axially compliant assembly 280, described above. The gear assembly 260
 operates to "step-up" rotation of the output wheel 274 relative to
 rotation of the pinion 262, as also described above. The amount of sliding
 movement of the control member 236 required to move the needle may be in a
 one to one ratio (i.e., movement of the control member 236 six millimeters
 relative to the housing 222 may result in axial movement of the needle six
 millimeters relative to the sheath), or the sliding movement may be in
 another ratio (e.g., two to one or three to one). Such movement is
 determined by the selection of the relative ratio of the gear teeth on the
 gears of the gear assembly, as discussed above. Regardless of the
 particular gear ratio, the gear assembly effectuates appropriate rotation
 of the through the axially compliant assembly 280, such that a
 predetermined and reasonable sliding movement of the control member 236
 relative to the housing 222 effectuates accurate, precise, and sufficient
 movement of the needle relative to the sheath at the distal end of the
 device.
 There have been described and illustrated herein embodiments of an
 endoscopic needle injection device. While particular embodiments of the
 invention have been described, it is not intended that the invention be
 limited thereto, as it is intended that the invention be as broad in scope
 as the art will allow and that the specification be read likewise. Thus,
 while a particular handle assembly has been disclosed, it will be
 appreciated that other handle assemblies can be used as well. For example,
 instead of utilizing a built-in syringe port, a "T" or "Y" connector could
 be provided at the proximal end of the device, preferably built into the
 handle, so that a flexible extension tube could extend from the device to
 a separate syringe for injecting fluid through the device. Such a "T" or
 "Y" connector, in its simplest form, has a distal end which connects to
 the sheath, a proximal end which incorporates a fluid seal which allows
 the shaft to rotate and translate through the fluid seal, and a side port
 which connects directly or by means of an extension hose to the syringe.
 In addition, while stops are shown adjacent the threaded connection of the
 needle sleeve and sheath sleeve, one or more stops may additionally or
 alternatively be provided at the control knob to prevent rotation of the
 control knob beyond a predetermined location, thereby limiting extension
 and retraction of the needle. Also, while in the second embodiment the
 needle sleeve is shown about the needle, it may alternatively be provided
 about the inner tubular member. Moreover, while in the second embodiment
 the shaft is shown coupled to the needle, the shaft may alternatively be
 coupled to the distal end of the inner tubular member. Furthermore, while
 particular types of gear boxes have been disclosed, it will be understood
 that gears with other numbers of gear teeth, and other relative ratios,
 can be used. Furthermore, while one gear assembly capable of transferring
 linear movement of a sliding control member into rotational movement of
 the shaft is shown, other gear assemblies, e.g., using bevel gears or an
 alternate rack and pinion gear, may be used. In addition, while the
 relative position of the needle relative to the sheath is indicated by the
 alignment of indicia, it will be appreciated that their relative positions
 may be indicated through a mechanical indicator operated by the gear
 assembly. Also, while one sliding assembly has been disclosed, it will be
 appreciated that other sliding components may be utilized. For example,
 the shaft may be provided with a tubular member having a non-circular
 bore, and the output end of the pinion may be non-circular and slidable
 within the non-circular bore. Furthermore, while square-shaped and
 hex-shaped keys have been disclosed for over the proximal end of the
 shaft, keys having other shapes may be used. Moreover, it is not necessary
 that the key on the shaft and bore on the end of the output end of the
 pinion have the same shape; only that they have interfering
 cross-sectional shapes. Also, while a stainless steel wire shaft has been
 disclosed, other torque transmitting shaft constructs and materials may be
 used. In addition, while axial needle movement of between ten to twelve
 millimeters is preferred, the device may be adapted to permit greater or
 lesser needle movement. Furthermore, while a seal is shown at the distal
 end of the device including an O-ring sealing against the threads of the
 sheath sleeve, other types of seals, at the sheath sleeve or elsewhere,
 may be used, so long as the seal is effective to prevent substantial
 leakage of fluid at the distal end of the device. For example, an O-ring
 may be provided proximal or distal the sheath sleeve, positioned against a
 relatively smooth inner surface of the sheath. It will therefore be
 appreciated by those skilled in the art that yet other modifications could
 be made to the provided invention without deviating from its spirit and
 scope as claimed.