arTICle | boTulInum ToxIn A |
Figure 8 Technique of injecting the procerus (note the position of the index finger and the thumb of the non-dominant hand)
the second and third fingertips of the non-dominant
hand, ask the patient to raise the eyebrows as high as possible, keeping the tip of the index finger positioned over the thickest part of the belly of the corrugator supercilii. Prior to inserting the needle, the index finger of the non-dominant hand should be advanced slightly cephalad and above the point of maximal muscle thickness. This usually is just above the eyebrow. The thumb now is placed at the margin of the supraorbital bony rim. The needle then is guided over the upper edge of the thumb, between it and the index finger, and inserted into the skin at a 60–90° angle until penetration into the corrugator supercilii can be felt (16,27). Entry into the corrugator is usually discerned when, after passing through the dermis and subcutaneous tissue, an abrupt release of resistance is felt as the needle penetrates fascia and muscle fibers of the corrugator. At this point, the needle may or may not impinge onto bone. If it does, the patient will sense sharp pain. The needle should then be withdrawn gently enough to move away from the bone, but not enough to exit the belly of the corrugator. The bore of the needle tip should be pointed upward and away from the globe, as it is slowly advanced into the belly of the corrugator supercilii in an oblique direction, slightly upward and lateral. Always remain deep within the muscle and
medial to the supraorbital notch and approximately 1.5– 2.0 cm superior to the supraorbital bony margin. Refrain from striking the frontal bone with the needle tip, so as not to inflict any additional pain upon the patient, which occurs when periosteum is pierced. However, this may not be avoidable when first learning how to find the deeply seated corrugators and effectively inject them at the proper depth. Placing the non-dominant index finger and thumb on the brow just above and below the eyebrow prior to injecting onabotulinumtoxinA serves many purposes. It prevents injecting onabotulinumtoxinA too low and close to the orbital rim. by applying direct pressure with the thumb inferior to the border of the supraorbital bony rim, binder et al. felt that they were able to reduce migration of onabotulinumtoxinA behind the orbital septum(16,27). This maneuver also assists in identifying the location
and direction of the corrugator supercilii, because it can be felt by light palpation. It also is important to inject slowly to avoid dispersing the onabotulinumtoxinA to surrounding, non-targeted muscles. now inject 4–10 u of onabotulinumtoxinA into the strongest portion of the muscle, which is located approximately 2 cm superior and 2 cm lateral to the nasion or the center of the concavity at the nasal root (16) (Figures 3 a & b). next withdraw the needle out of the skin and redirect the tip of the needle medially in the direction of the nasion. Insert the needle at or adjacent to the most medial aspect of the superciliary arch approximately 2cm directly superior to the ocular caruncle at the inner canthus (Figure 6). Injecting another 2-6 u of onabotulinumtoxinA at this point of maximum muscle contraction will treat the medial vertical muscle fibers of the orbital orbicularis oculi and the depressor supercilii. because the fibers of the orbicularis oculi are closely adherent to the overlying skin, injections can be given either intradermally or in the superficial subcutaneous plane at this site. Superficial injections here also should affect the depressor supercilii and avoid puncturing the supratrochlear vessels and nerve. A pleasing vertically upward lift to the medial brow can be accomplished by this technique, if fibers of the frontalis are not inadvertently affected(35-36). Gentle massage in an upward and lateral direction for a few seconds immediately after the injection helps relieve the acute pain the patient might have experienced, and can disperse the toxin into the areas
intended for treatment. Heavy-handed massage will definitely disperse the onabotulinumtoxinA beyond the area and into muscle fibers not intended for treatment, i.e. into the fibers of the lower frontalis, which can produce brow ptosis. next, watch as the patient frowns again, and notice to
42 ❚
what extent the mid brow adducts toward the glabella. Stronger corrugators will visibly pull the skin just above the eyebrows medially. In some patients, additional corrugations vertically along the brow that are parallel to the central vertical glabellar lines also will be formed
March 2011 |
prime-journal.com
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