Botulinum toxin Flashcards
What muscle can be affected if botulinum injection occurs less than 1 cm above the eyebrow or lateral to the mid pupillary line? What is the effect?
Levator palpebrae superioris –> Leads to eyelid droop
What is the treatment for eyelid ptosis?
Apraclonidine 0.5% eye drops (alpha-2 agonist that causes Muller muscles to contract and provides some compensation for weakened levator palpebrae superioris
What is the function of the light chain in the botulinum toxin?
Catalyzes the proteolysis of one of the three synaptosomal-associated protein receptors/SNARE proteins
These include: synaptosome-associated protein 25 kD, vesicle-associated membrane protein or synaptobrevin and syntaxin-1
What is the function of the heavy chain in the botulinum toxin?
Responsible for the actual attachment to the motor nerve axon terminal and translocation across the cell membrane
What proteins are cleaved by botulinum toxin types A and E?
Synaptosome-associated protein 25 kD
What is the mechanism of botulinum toxin B? (as compared to A?)
It cleaves the synaptobrevin protein (as compared to the SNAP-25 protein)
What is different about the incobotulinum toxin A formulation?
It does not require refrigeration if unopened and lacks the complexing proteins
What muscle, if injected, causes an asymmetric smile with effort (i.e. not apparent when not trying to smile)? What should be done to avoid this?
Depressor labii inferioris
When injecting depressor anguli oris, inject lateral to the nasolabial folds (avoids overlapping fibers from the depressor labii inferioris
What would be the effect of botulinum toxin injection into the obicularis oris muscle?
Upper lip drop and alteration of phonation due to lip sphincter weakness and incompetence (cant purse lips)
What muscle should be injected to improve resting smile?
Depressor anguli oris –> Is used to frown, and allows elevators of the corner of the mouth to function w/ less opposition
What muscles should be injected if a pt notes a small that shows too much gums?
The “gummy smile” can be alleviated by injection into the levator labii superioris alaeque nasi
What sx’s might be noted with injection of the zygomaticus major muscle?
Facial droop at rest (as compared to asymmetric small w/ pulling = depressor labii inferioris)
What muscle is responsible for marionette lines?
Depressor anguli oris (pulls the corner of the mouth downwards)
What is the function of the buccinator muscle?
Allows blowing up of the cheeks and presses the cheek against the teeth
What is the function of the procerus muscle?
Pulls the medial portion of the eyebrows and glabellar skin downward
What muscle leads to the formation of horizontal glabellar lines?
Procerus
What is the function of the risorius muscle?
Draw the corners of the mouth back (produces smiles)
What is the main muscle that contributes to smiling?
Zygomaticus major (elevates and draws corners of mouth laterally)
How many subtypes of botulinum toxin exist and how many are used in dermatology?
8 exist (A-H), but 2 are used in dermatology (A/B)
What is the mechanism of botulinum toxin injection?
Inhibits release of Ach at motor neuron presynaptic terminals through blockade of the SNARE complex, which prevents the release of Ach and leads to chemical denervation of the muscle
Over time the muscle undergoes atrophy
What is the onset and duration of the effect seen with botulinum toxin injection?
Can take up to a week for full effect and lasts usually ~3 months
In which direction do wrinkles/rhytides run in comparison to muscle fibers?
Perpendicular
What two subtypes of botulinum toxin are used in dermatology and how many versions are there currently for each one?
Botulinum toxins A and B are used
There are 3 versions of botulinum toxin A and one of botulinum toxin B
What are the 3 generic and brand names for botulinum toxin A in use?
OnabotulinumtoxinA (Botox), AbobotulinumtoxinA (Dysport), and IncobotulinumtoxinA (Xeomin)
Xeomin is the only one that does not contain complexing proteins
