Ophthalmologists specializing in eye muscle disorders (strabismus) had developed the method of EMG-guided injection (using the electromyogram, the electrical signal from an activated muscle, to guide injection) of local anesthetics as a diagnostic technique for evaluating an individual muscle’s contribution to an eye movement. Because strabismus surgery frequently needed repeating, a search was undertaken for non-surgical, injection treatments using various anesthetics, alcohols, enzymes, enzyme blockers, and snake neurotoxins. Finally, inspired by Daniel Drachman’s work with chicks at Johns Hopkins, Alan B Scott and colleagues injected botulinum toxin into monkey extraocular muscles. The result was remarkable: a few picograms induced paralysis that was confined to the target muscle, long in duration, and without side-effects.
According to the PREEMPT injection paradigm, one injection of 5 units of onabotulinumtoxinA is administered to one site in the procerus muscle. The procerus injection site is approximately midway between the two corrugator injections. In order to confirm the location of the procerus muscle, the patient is asked to furrow the brow, which will activate the belly of the muscle causing the medial furrowing to occur. Once identified, 5 units of onabotulinumtoxinA is injected superficially into the belly of the muscle at a 90° angle to ensure the injection is administered into the procerus rather than the frontalis. Injections placed too superiorly may inadvertently lead to penetration of the frontalis muscle.
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Children do very well after having this procedure in our clinic and are not upset when they leave. We rarely use sedation. We use distraction and a quick injection method instead. In rare cases, localization of a muscle may be needed using an electromyograph (EMG) machine or electric stimulator. If this is needed we will discuss this before scheduling the injections.
BOTOX is administered about every three months, and must be injected at the site of each nerve trigger, relaxing the surrounding muscles so that they won’t compress the nerve and trigger a migraine. It is a potent drug, and we only recommend using it if other preventative treatment options haven’t helped you. It is generally only administered to patients who have at least 14 headaches a month, or don’t respond to other treatments.
Botulinum toxin produced by Clostridium botulinum is the cause of botulism. Humans most commonly ingest the toxin from eating improperly-canned foods in which C. botulinum has grown. However, the toxin can also be introduced through an infected wound. In infants, the bacteria can sometimes grow in the intestines and produce botulinum toxin within the intestine and can cause a condition known as floppy baby syndrome. In all cases, the toxin can then spread, blocking nerves and muscle function. In severe cases, the toxin can block nerves controlling the respiratory system or heart, resulting in death. Botulism can be difficult to diagnose, as it may appear similar to diseases such as Guillain–Barré syndrome, myasthenia gravis, and stroke. Other tests, such as brain scan and spinal fluid examination, may help to rule out other causes. If the symptoms of botulism are diagnosed early, various treatments can be administered. In an effort to remove contaminated food which remains in the gut, enemas or induced vomiting may be used. For wound infections, infected material may be removed surgically. Botulinum antitoxin is available and may be used to prevent the worsening of symptoms, though it will not reverse existing nerve damage. In severe cases, mechanical respiration may be used to support patients suffering from respiratory failure. The nerve damage heals over time, generally over weeks to months. With proper treatment, the case fatality rate for botulinum poisoning can be greatly reduced.
Tell your doctor about all your medical conditions, including: plans to have surgery; had surgery on your face; have trouble raising your eyebrows; drooping eyelids; any other abnormal facial change; are pregnant or plan to become pregnant (it is not known if BOTOX® Cosmetic can harm your unborn baby); are breast-feeding or plan to (it is not known if BOTOX® Cosmetic passes into breast milk).