Abstract:
Device for administering an injection is generally discussed herein with particular discussions extended to devices for stimulating a cavity below the skin and administering a dosage in the stimulated cavity and method of using the same. The dosage can be medication for health and/or cosmetic treatments. The device includes a housing and a needle mounted thereto. A vacuum source is in communication with the housing for creating a vacuum inside the housing while a power source is in communication with the needle for supplying current to the needle. The combination current and vacuum stimulates a cavity for injection. A vacuum source may also be used to advance a piston to discharge medicament from a needle mounted on a syringe.

Description:
[0001]    Device for administering an injection is generally discussed herein with particular discussions extended to devices for stimulating a cavity below the skin and administering a dosage in the stimulated cavity and method of using the same. The dosage can be medication for health and/or cosmetic treatments. 
       BACKGROUND 
       [0002]    There are a number of means for delivering medications for treatment of diseases and illnesses including orally and via a syringe. Historically when using a syringe to deliver medications, a subject will generally be poked by a needle, either in the arm, leg, or buttock, and the medications delivered to the injection site through the lumen in the needle. The injection can vary from one caregiver to another as the location and depth of an injection can vary from one caregiver to another, which, for the most part, is not critical. 
         [0003]    More recently, syringes are used to deliver medications for treating wrinkles, i.e., for cosmetic reasons. In these instances, a caregiver will randomly inject wrinkle areas of the face at varying depths to deliver neurotoxin, such as BOTOX®, or injectable fillers, such as ZYDERM®, ZYPLAST®, RESTYLANE®, RADIANCE®, and ARTFILL™, just to name a few. As these medications are injected to wrinkle areas at random depths, their effectiveness and efficiency are less than optimal. 
         [0004]    Accordingly, there is a need for a device that ensures a more consistent delivery of medications and method of using same. Such a device not only can be used for treating wrinkles but can also be used for non-cosmetic treatments, such as for delivering anesthesia and slow release birth control medications. 
       SUMMARY 
       [0005]    The present invention may be implemented by providing an injection apparatus comprising a needle assembly comprising a needle mounted to a housing; a vacuum source connected to the housing for creating a vacuum inside the housing; and a power supply directly or indirectly connected to the needle for supplying a current to the needle. 
         [0006]    The present invention may also be practiced using a method for injecting a subject comprising (a) placing an injection apparatus on a skin of the subject; the injection apparatus comprising: (1) a needle assembly comprising a needle mounted to a housing; (2) a vacuum source connected to the housing; (3) a power supply directly or indirectly connected to the needle for supplying a current to the needle; (b) penetrating the skin of the subject with the needle; and (c) delivering an injection to the subject. 
         [0007]    In yet another aspect of the present invention, there is provided a method for injecting a subject comprising penetrating a skin with a needle; stimulating a cavity below the skin using an electric stimulator and a vacuum source; and delivering medication to the cavity. 
         [0008]    In still yet another aspect of the present invention, there is provided a method for injecting a subject comprising: penetrating a skin with a needle; stimulating a fascia layer below the skin with an electric stimulator; and delivering a medicament adjacent the stimulated fascia. 
         [0009]    In yet another aspect of the present invention, there is provided an injection apparatus comprising an injection module housing defining an interior cavity comprising a nozzle for connecting to a vacuum source, a first receiving end for receiving a syringe, and a second receiving end for accommodating an end object for sealing the second receiving end, wherein the nozzle is configured to communicate with a vacuum source to place the interior cavity under a vacuum. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0010]    These and other features and advantages of the present invention will become appreciated as the same become better understood with reference to the specification, claims and appended drawings wherein: 
           [0011]      FIG. 1  is an exemplary schematic diagram of a skin tissue; 
           [0012]      FIG. 2  is a schematic diagram of an injection assembly provided in accordance with aspects of the present invention; 
           [0013]      FIG. 3  is a semi-schematic cross-sectional side view of an exemplary needle assembly provided in accordance with aspects of the present invention; 
           [0014]      FIG. 4  is a schematic diagram of an alternative injection assembly provided in accordance with aspects of the present invention; 
           [0015]      FIG. 5  is a schematic diagram of the injection assembly of  FIG. 2  used on a subject; 
           [0016]      FIG. 6  is a semi-schematic diagram of the skin tissue following an injection using an injection device provided in accordance with aspects of the present invention 
           [0017]      FIG. 7  is a semi-schematic diagram of an alternative injection assembly provided in accordance with aspects of the present invention; 
           [0018]      FIG. 8  is a semi-schematic diagram of the injection assembly of  FIG. 7  with an accordion seal attached to the elongated shell; 
           [0019]      FIG. 9  is a semi-schematic diagram of the injection assembly of  FIG. 7  with a leveling plate; and 
           [0020]      FIG. 10  is a semi-schematic diagram of an alternative injection assembly which uses a vacuum source to advance a plunger for delivering medications from a syringe. 
       
    
    
     DETAILED DESCRIPTION  
       [0021]    The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred injection devices, which are exemplary embodiments provided in accordance with aspects of the present invention, and is not intended to represent the only forms in which the present invention may be constructed or utilized. The description sets forth the features and the steps for constructing and using the injection devices of the present invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. As denoted elsewhere herein, like element numbers are intended to indicate like or similar elements or features. 
         [0022]    This application is related to Ser. No. 10/932,751, filed Sep. 2, 2004, entitled INTEGRATED NEUROTOXIN INJECTION SENSING AND CONTROL DEVICE, the contents of which are expressly incorporated herein by reference as if set forth in full. 
         [0023]    Referring now to  FIG. 1 , there is shown an exemplary schematic cross-sectional view of a skin tissue of a human body, which is generally designated  10 . As is well known in the medical field, the skin tissue  10  comprises a skin layer, which are the epidermis  12  and dermis  14  layers, a superficial fascia layer  16 , a deep fascia layer, and a muscle layer, shown collectively as  18 . In the facial area however, there is no deep fascia layer. Instead, facial muscles are embedded in the superficial fascia layer  16 . The superficial fascia layer  16  in the facial area, herein the fascia  16 , thus comprises a loose network of connective tissue bundles, collagen, and elastin, which blend with the dermis. 
         [0024]    Wrinkles have been described as aging, sun-damaged skin, the loss of elastin and/or collagen, etc. Whether or not due to one or more of these reasons, from the schematic shown, a wrinkle  20  on the skin outer surface  22  is simply an outward reflection of the movement  24  of muscles underlying the skin along an axis perpendicular to the skin, i.e., the Z axis. Thus, as muscles are embedded in the superficial fascia layer  16  in the facial region, wrinkles in the facial region is movement of the fascia layer  16  along the Z axis. A void space  26  formed from the original skin contour  22  and the wrinkled skin  20  are thus both formed due to movement of the fascia layer  16 . 
         [0025]    In one aspect of the present invention, wrinkle treatment involving recovering at least part of the void space  26  is provided by injecting medications, which can be a filler or a neurotoxin, below the skin  22  to either (1) fill-out the skin to create a more even line with the top skin contour  22  or (2) paralyze the muscles that cause the skin to wrinkle  20  so that they relax and not contract along the Z axis. More preferably, medications are injected in between the dermis layer  14  and the fascia  16  to treat wrinkles. Most preferably, medications are injected in a cavity (not shown) formed between the dermis layer and the fascia using a device of the present invention for consistent and prolonged wrinkle treatment, as further discussed below. Other medications not presently approved for wrinkle treatment but in the future are approved may also be used with the devices of the present embodiment provided they are useable with a syringe. 
         [0026]    Referring now to  FIG. 2 , an exemplary injection assembly for delivering an injection in accordance with aspects of the present invention is shown, which is generally designated  28 . In one embodiment, the injection assembly  28  comprises a master controller  30  and an injection module  32  comprising a needle assembly  34  mounted to a housing  36 . In general, the master controller  30  is configured to supply an electrical stimulation to the facial tissue via the needle assembly  34 , a vacuum to the housing  36  to create a pulling force on the skin  22 , and pressurized gas to the needle assembly  34  to inject medications, as further discussed below. The injection module  32  is configured to penetrate the skin, transfer low voltage to provide stimulation to the facial tissue, and deliver medications. 
         [0027]    In one exemplary embodiment, the master controller  30  comprises a vacuum pump (not shown), pressurized gas supply (not shown), a power supply device (not shown), and electronics for regulating the vacuum pump, gas flow, and either voltage and/or amperage supplied by the power supply device. The injection module  32  comprises a wall enclosure  38 , a cap  40 , and the needle assembly  34 , as previously discussed. The injection module  32  also comprises a nozzle  42 , a first open end  44  comprising a pliable seat  46 , and a second open end  48  comprising a mating connector  50 , which in one exemplary embodiment is a corresponding threaded end for receiving the cap  40 . The nozzle  42  is preferably a hose barb connector for connecting to an air hose and may include a rocker pinch valve as disclosed in U.S. Pat. No. 6,340,096. The pliable seat  46  is preferably a foam-based gasket but may be a rubber-base gasket removably adhered to the wall enclosure end with adhesive. In one exemplary embodiment, the pliable seat  46  is disposable and comprises pressure sensitive adhesive for providing a vacuum tight seal with the face, as further discussed below. The pliable seat  46  comprises an opening and a configuration that matches the configuration of the wall enclosure  38 , which in one exemplary embodiment is a cylindrical wall enclosure having two open ends  44 ,  48 . 
         [0028]    The cap  40  comprises an O-ring  52  seated in a groove, a mating connector  54 , a vacuum breaker  56 , a receiver (not shown) for receiving the needle assembly, a pneumatic connector (not shown) for connecting to the pressure source, and a terminal connector (not shown) for connecting to the power supply. In one exemplary embodiment, the vacuum breaker  56  is configured for manual opening by turning a valve or a piston to open the housing to atmosphere to enable removable of the housing. As is readily apparent to a person of ordinary skill in the art, any of the various components on the wall enclosure  38  and the cap  40  may be located elsewhere on the wall enclosure and the cap. For example, the vacuum breaker  56  may be located on the wall enclosure  38  instead of on the cap  40  and the nozzle  42  may be located on the cap  40  instead of the wall enclosure  38 . Furthermore, instead of using threads to couple the cap  40  and the wall enclosure  38  together, in an alternative embodiment, detents or straps may be used. Preferably however, threads are used to enable adjustable engagement of the cap  40  to the wall enclosure  38  to thereby adjust the length of the needle  58  that extends distally of the edge of the pliable seat  46 . In one exemplary embodiment, a reservoir for storing medications is located on the cap and the needle assembly, particularly the dispensing hub  72  ( FIG. 3 ), is in communication with the reservoir. 
         [0029]    The master controller  30  is placed in communication with the injection housing  36  by connecting the nozzle  42  to the vacuum pump using a hose  60 , connecting the pressurized gas to the pneumatic connector on the cap  40  using a hose  60 , and connecting the terminal connector on the cap to the power supply device using a cable  62 . In one exemplary embodiment, the power supply device and the vacuum pump are both located inside the controller  30  while the pressurized gas supply is external to the controller. However, the pressurized gas supply, which may be an air pump, may also be located inside the controller  30 . Preferably, the vacuum source and the gas supply are both external of the controller. For example, the vacuum source can be part of a central vacuum source and the gas supply can be a pressurized gas tank, of either nitrogen or air. The controller  30  preferably controls current flow and pressurized gas to the needle assembly  34  as well as timing of the current flow and the gas flow for reasons further discussed below. 
         [0030]    Referring now to  FIG. 3 , a needle assembly  34  provided in accordance with aspects of the present invention is shown. The needle assembly  34  resembles a catheter assembly and comprises a needle  58  having a sharpened needle tip  66  attached to a needle hub  68 , and a tube  70  attached to a dispensing hub  72 . In one exemplary embodiment, the dispensing hub  72  comprises an engagement end  67  configured to engage the receiver on the cap  40 . The dispensing tube  70  and the needle  58  in the present embodiment are both made from a metallic material, preferably of stainless steel. In one exemplary embodiment, the needle hub  68  and the dispensing hub  72  are both co-molded with a metallic insert  74  comprising a metallic strip  76  comprising an exposed lead  78 . The two leads  78  are configured to couple to a power supply device to impart an electric current to the facial tissue for stimulating a cavity, as further discussed below. The metallic inserts  74  may each comprise a cylindrical configuration or an open curved metallic section configured to contact with the needle. 
         [0031]    In one exemplary embodiment, a gap or space  73  is provided in the annular space between the needle  58  and the dispensing tube  70 . This gap  73  is in communication with an opening or vent port  75  incorporated in the needle hub  68 . Thus, when the needle  58  is inserted into a skin tissue, the area of the skin tissue that surrounds the needle tip  66  is in fluid communication with the vent port  75 , which is in communication with the atmosphere. As further discussed below, fluid to be dispensed by the needle assembly  34  is dispensed through the dispensing hub  72  and dispensing tube  70  and out of the end opening  77  of the tube. In an alternative embodiment, a plurality of vent ports  75  are incorporated in the needle hub  68 . In yet another aspect of the present invention, the needle tip  66  of the needle  58  comprises a non-coring tip, which typically includes a bend in the shaft. 
         [0032]      FIG. 4  is an alternative injection assembly  80  provided in accordance with aspects of the present invention. In the present embodiment, a hand vacuum pump  82  is incorporated for providing a vacuum and a hand activated valve  84  connected to a line  86  and in communication with the needle assembly  34  for regulating medication flow out of the dispensing tube  70 . The valve  84 , when activated to open, is opened on one side to the atmosphere. 
         [0033]    Referring now to  FIG. 5 , the injection assembly  28  is shown used on a patient. In an office setting, a subject or patient is first directed to lay down in a supine or semi-recumbent position in a chair and the face to be treated is positioned substantially horizontally. The injection module  32 , with the needle  58  adjusted to extend about 0.4 cm to about 1.5 cm distally from the end of the pliable seat  46  and the various connectors and lines connected to the master controller  30 , is then placed on the facial skin  22  of the patient. However, the length can vary depending on the treatment and location of injection. The injection module  32  should be placed directly over a wrinkle to be treated. Placement of the module  32  results in the needle  58  penetrating the skin at the wrinkled area to a depth set by the position of the needle tip  66  relative to the pliable seat  46 . If the injection module  32  is connected to an external vacuum source, a vacuum is created inside the interior cavity  87  of the wall housing  36  without initiating the master controller  30  otherwise a vacuum power switch  88  on the master controller  30  is activated to initiate the vacuum pump for generating a vacuum in the interior cavity. A soft vacuum of about 7 to about 14 psia should be established inside the interior cavity. A vacuum pressure transducer may be incorporated to verify the vacuum inside the cavity. Preferably the vacuum is kept to about 9-13 psia. The skin  23  under the vacuum bulges outwardly into the interior cavity  87  of the housing  36 , which is shown exaggerated for discussion purposes. 
         [0034]    Once a sufficient vacuum is established, a current is sent to the needle assembly  34  by activating a power source switch  90 . A current of about 1.5 mA to about 5 mA supplied to the needle is preferred with a current of about 2 mA to about 3 mA being more preferred. The higher the current, the more the fascia  16  will contract, as further discussed below. In one exemplary embodiment, the controller  30  has built-in electronics to regulate the amount of current output to the needle  58 , which may be adjusted by turning a dial  92 . 
         [0035]    The current provided by the controller  30  to the terminal connector (not shown) located on the cap  40  and then to the needle  58  and dispensing tube  70  via the leads  78  on the needle hub  68  and dispensing hub  72  causes the muscles adjacent the needle and dispensing tube to contract. The contraction is caused by an electrical stimulation to an area located around the needle that is known as the neuromuscular junction. Current discharged in this region produces a muscular response. The contraction is caused by an electrical stimulation to an area located around the needle, and therefore first will stimulate the neuromuscular junction lying within the fascia that is adjacent to the needle body. Current discharged in this region produces a muscular contraction following the release of acetylcholine, which initiates an action potential and this then propagates through the rest of the muscles. 
         [0036]    The muscles, which as previously discussed are embedded in the fascia, move away from the current source, i.e., the needle. Normally this causes the skin  22  to move with the fascia. However, as a vacuum is applied to the skin surface directly over the axis defined by the needle  58 , the fascia  16  separates from the skin, i.e., from the dermis  14  and epidermis  12 . This separation is facilitated by the vent hole  75  located in the needle hub  68 , which assists in breaking the surface tension between the skin and the fascia.  FIG. 6  is a graphical depiction of a cavity  94  created below the skin due to the combination vacuum applied to the skin surface  22  and electrical current supplied to the muscles subjacent the vacuum source. This cavity region is also known in the medical field as a dead space or a bloodless plane. 
         [0037]    The cavity  94  forms almost instantaneously as the flow of current is applied to the needle. In one exemplary embodiment, a small volume of pressurized gas is sent to the needle assembly  34  to push medications into the cavity shortly following the flow of current. The pressurized gas can be a low pressure gas of about 1-3 psig and a flow volume of about 0.02 cc to about 0.8 cc, which would be equivalent to the volume of medications injected into the cavity  94  from the dispensing tube  70 . In one exemplary embodiment, the controller automatically senses the vacuum inside the interior cavity  87  of the housing  36 , supply a current to the needle  58  and dispensing tube  70  when an appropriate vacuum is sensed, and delivers a quantity of pressurized gas to the needle a short time interval following the supply of current to the dispensing hub  72  to then deliver medications to the cavity  94 . Depending on the treatment, medications delivered to the cavity can be any number of products including fillers and neurotoxin. However, medications can be any number of medications depending on the type of treatment or preventative care in question. 
         [0038]    With reference to  FIG. 4  in addition to  FIG. 6 , if a different injection assembly is used, such as the injection assembly  80  of  FIG. 4 , then the injection process includes placing the injection module  32  over an area to be injected, creating a vacuum using a vacuum pump  82  or other vacuum source, such as a separate vacuum pump, opening the valve  84  connected to the needle assembly  84 , and then sending a current from the controller  30  to the needle. A cavity will form as previously discussed. However, rather than supplying pressurized gas to inject medications to the cavity  94 , medications are automatically drawn into the cavity  94  due to a vacuum that is formed as the cavity is created. The valve  84  may be closed shut following a brief moment, such as 2-6 seconds following the flow of current. A second injection can now be made by moving the injection module  32  to a different location to be injected and repeating the described steps. As the housing  36  is under a vacuum, the vacuum breaker  56  should be activated to release the vacuum. 
         [0039]    Referring now to  FIG. 7 , a semi-schematic cross-sectional side view of yet another alternative injection assembly  96  provided in accordance with aspects of the present invention is shown. The injection assembly comprises an injection module  98  and a master controller (not shown) similar to the controllers previously discussed. In one exemplary embodiment, the injection module  98  comprises a housing  100  comprising a nozzle  42 , a vacuum breaker  56 , and a needle assembly  102  attached to the housing. In one exemplary embodiment, the needle assembly  102  is attached to a top surface  104  of the housing  100 , which may be an integrally formed top surface or a separate cap to be connected to the wall enclosure  106 . The wall enclosure  106  is shown with a break line  108  representing a variable housing length to be determined depending on the needle and needle assembly. A pliable seat  46  is incorporated at the end edge of the wall enclosure  106  to serve as a soft seating surface. 
         [0040]    In one exemplary embodiment, the needle assembly  102  is similar to the needle assembly shown in  FIG. 3  with a few changes. In particular, a second opening  110  is incorporated in the needle hub  68  and an elongated shell  112  comprising a pliable seat  114  is coaxially disposed with the needle  58 . The elongated shell  112  may be attached to the needle hub  68  by either interference fit or threaded engagement. An interior space  116  is defined interiorly of the shell  112 , which is in communication with the first opening  75  and second opening  110  on the needle hub  68 , which is in communication with the atmosphere. 
         [0041]    When the injection assembly  96  is used on a patient, such as that shown in  FIGS. 4 and 5 , and the housing is under a vacuum, the space around the needle defined by the shell  112  is not in a vacuum whereas the space outside the shell  112  and inside the housing  100  is under a vacuum. Thus, when a current is applied to the leads  78  on the needle hub  68  and the dispensing hub  72 , muscles will contract along the Z-axis and will tend to pull the skin located inside the shell  112  in the same direction. The skin, however, is held secured by the vacuum around the area between the shell  112  and the housing  100 . This configuration, as compared to that shown in  FIGS. 4 and 5 , has been found to effectively stimulate a cavity near the needle tip  66  for depositing medicament stored inside the reservoir  118  defined by the dispensing hub  72 . Similar to previously described embodiments, medicament may be dispensed using a pressurized gas source coupled to the reservoir  118  or may be gravity fed using a combination valve and tubing. 
         [0042]    The interface between the needle hub  68  and the housing  100 , and particularly the top surface  104  of the housing, may be any known prior art attachment means, including interference fit, friction fit, and threaded engagement. Preferably, the interface allows adjustment to the needle so that the needle tip extension, and therefore the depth of penetration of the needle, beyond the end edge of the housing  100  may be adjusted. 
         [0043]      FIG. 8  is a semi-schematic cross-sectional view of the injection assembly  96  of  FIG. 7  with an accordion seal  120  attached to the end edge of the elongated shell  112 . The accordion shell  120  may be made from an elastomeric material and may be attached to the shell using detents or tongue and groove arrangement. The accordion seal  120  allows the interior space to remain constant by flexing and compensating for different curvatures of the face as the injection assembly  96  is moved from one injection site to another. 
         [0044]      FIG. 9  is a semi-schematic cross-sectional side view of the injection assembly  96  of  FIG. 7  with a leveling plate  122  attached to the opening of the elongated shell  112  and having an opening  124 . In one exemplary embodiment, the leveling plate comprises a thermoplastic plate. The plate  122  is configured to provide a base line or an injection site that is level relative to the needle tip. Thus, when vacuum is applied to the skin for an injection, the area under the needle ensures that any skin that is raised by the vacuum is leveled by the plate  122 . This in turn ensures that the injection site is level from site to site so that the depth of the injection is the same or nearly the same from site to site. 
         [0045]      FIG. 10  is a semi-schematic side view of yet another injection assembly provided in accordance with aspects of the present invention, which is generally designated  126 . In one exemplary embodiment, the injection assembly  126  comprises a syringe  128  comprising a needle  130 , shown with a needle cap  132 , a barrel  134 , a plunger  136  having a push flange  140 , and a piston  138 . The syringe  128  may be any number of prior art syringe, which may include an integrated needle as shown or a separate needle with needle hub. In the figure, a second piston  138 ′ is shown distally advanced inside the barrel  134 , which depicts an injection wherein the piston  138  is advanced from a proximal position on the barrel  134  to a more distal position. In one exemplary embodiment, the barrel  134  incorporates one or more stoppers  142  located on its external surface for registering the barrel relative to an injection housing, as further discussed below. 
         [0046]    The injection assembly  126  further comprises an injection module  144  comprising a housing  146  comprising a loading cap  148  and an injection body section  150 . The housing  146  may be made from a rigid thermoplastic material or a metal, such as aluminum or stainless steel. In one exemplary embodiment, the loading cap  148  comprises a bore  152  comprising a tapered cylindrical wall surface, tapers inwardly from a proximal point to a distal point, near a groove for accommodating an O-ring  156 . In one exemplary embodiment, the cap  148  comprises a shoulder comprising a threaded end  158  comprising a second groove for accommodating a second O-ring  156 . The cap  148  is configured to slide onto the barrel from the rear end of the barrel  134 , where the plunger  136  projects through the barrel. The cap is pushed distally forward until the end edge  160  of the cap contacts the one or more stoppers  142 . 
         [0047]    Medication  162  may now be filled into the barrel by aspirating the plunger  136  to draw a vacuum. The injection body section  150  is now threaded to the cap  148  and the split-line between the body section  150  and the cap  148  sealed by a second O-ring  156 . As shown, the injection body section  150  comprises a vent port or opening  164  comprising a nozzle  166 , which may be a barb connector, and an activating piston  168  in dynamic sealing arrangement with the interior wall surface  170  of the body section  150 . 
         [0048]    The injection assembly  126  is configured to deliver an injection not by pushing the plunger  136  with a finger, such as a thumb, but by activating the activating piston  168  using a vacuum source. In one exemplary embodiment, the nozzle  166  on the body section  150  is connected to a vacuum source using a hose  172 . The vacuum source can be any one of an electric vacuum pump  174 , a manual hand vacuum pump  176 , or a vacuum header  178 , typically in hospitals or other institutions. 
         [0049]    When the interior cavity  176  of the injection module  144  is subjected to a vacuum, the activating plunger  168  is automatically drawn distally. At some point, the activating plunger  168  will contact the push flange  140  and pushes the push flange and the plunger  136  into the barrel  134 , which in turn, via the piston  138 , pushes medications  162  inside the barrel out of the needle  132 . It has been found that a vacuum of as little as 9-14 psia will effectively move the activating plunger  168  to then push the plunger  136 . However, for injecting a more viscous fluid, a vacuum of about 1-6 psia may be required. 
         [0050]    In an alternative embodiment, the piston  168  is fixed to the housing  146 , i.e., does not move relative to the housing. The piston  168  can thus be an end cap or the like that can either be permanently secured to the open end  169  of the housing  146  or removable from the open end  169 , such as by incorporating threads. In the present alternative embodiment, the barrel  134  of the syringe is configured to move into the housing  146  upon exposing the nozzle  166  to a vacuum source. In one exemplary embodiment, the stoppers  142  on the exterior surface of the barrel  134  are eliminated. Hence, when the interior cavity  176  is under a vacuum the barrel  134  and the plunger  136  both move proximally into the housing  146 . At some point, the push flange  140  on the plunger hits the stationary piston  168  while the barrel  134  continues to move. This motion causes the plunger  138  to eventually contact and push medications inside the barrel out of the needle  130 . In short, the present alternative embodiment is configured to discharge fluid out of the needle  130  while at the same time move the barrel  134  proximally relative to the injection module. 
         [0051]    Although limited embodiments of the injection device and methods of using same have been specifically described and illustrated herein, many modifications and variations will be apparent to those skilled in the art. For example, separate controllers for controlling different functions may be incorporated instead of just one, different ways to supply current to the facial tissue using different means instead of via the leads in the needle and catheter hubs as described, and different ways to stimulate a void or cavity instead of using a stimulator in combination with a vacuum. Furthermore, it is understood and contemplated that features specifically discussed for one injection assembly may be adopted for inclusion with another injection assembly, provided the functions are compatible. Accordingly, it is to be understood that the injection assemblies and their components constructed according to principles of this invention may be embodied other than as specifically described herein. The invention is also defined in the following claims.