Botulinum toxin exerts its effect by cleaving key proteins required for nerve activation. First, the toxin binds specifically to nerves which use the neurotransmitter acetylcholine. Once bound to the nerve terminal, the neuron takes up the toxin into a vesicle. As the vesicle moves farther into the cell, it acidifies, activating a portion of the toxin which triggers it to push across the vesicle membrane and into the cell cytoplasm.[1] Once inside the cytoplasm, the toxin cleaves SNARE proteins preventing the cell from releasing vesicles of neurotransmitter. This stops nerve signaling, leading to paralysis.[1]
OnabotulinumtoxinA is the only treatment approved by the United States Food and Drug Administration for the prevention of headaches in adult patients with chronic migraine (CM). CM assessment involves a detailed history to rule out secondary sources of headache, establish migraine features, and assess the total number of headache days. In order to diagnose migraine, the patient should have had at least five attacks that involve migraine features, as outlined below. In adults, untreated attacks usually last 4 or more hours.

Since Botox made its first appearance in the med-spa world, a number of similar treatments have also become available. These include Dysport, another Botulinum toxin type A injectable, as well as dermal fillers (which use hyaluronic acid to plump skin) such as Juvéderm, Restylane, and Perlane. The decision to choose between Botox vs Dysport depends largely on the results you're hoping to achieve. For more information, check out the following guides:

In double-blind, placebo-controlled chronic migraine efficacy trials (Study 1 and Study 2), the discontinuation rate was 12% in the BOTOX treated group and 10% in the placebo-treated group. Discontinuations due to an adverse event were 4% in the BOTOX group and 1% in the placebo group. The most frequent adverse events leading to discontinuation in the BOTOX group were neck pain, headache, worsening migraine, muscular weakness and eyelid ptosis.
Once the protein stops functioning at the neuromuscular junction, it is broken down into its harmless components (amino acids) and either recycled for use in other proteins or excreted by the kidneys. "The bigger the muscle, the quicker you'll see motion return," says Rowe. "Likewise, the smaller the muscle, the longer the effect of botox lasts." It doesn't have a tolerance effect, either—your body never gets used to Botox.

The patient’s neck stability, posture, torsion, and symmetry should be assessed to determine whether he or she may be at increased risk for adverse events prior to the first injection cycle. A patient with preexisting neck pain and/or weakness may be at higher risk for exacerbation of the condition upon injection of the occipitalis, cervical paraspinal, or trapezius muscle groups. Patients with smaller frames may be at higher risk for neck weakness. Indicated injection sites can still be injected with minimal side effects and unwanted outcomes as long as correct injection sites are targeted and treatments are administered using a superficial approach with avoidance of the mid and lower cervical regions. The cervical paraspinal muscle group is made up of multiple muscles including the trapezius, splenius capitis and cervicis, and semispinalis capitus. This group of muscles helps support the neck, including extension of the head.

The safe and effective use of BOTOX depends upon proper storage of the product, selection of the correct dose, and proper reconstitution and administration techniques. An understanding of standard electromyographic techniques is also required for treatment of strabismus, upper or lower limb spasticity, and may be useful for the treatment of cervical dystonia. Physicians administering BOTOX must understand the relevant neuromuscular and structural anatomy of the area involved and any alterations to the anatomy due to prior surgical procedures and disease, especially when injecting near the lungs.
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The incidence of UTI increased in patients who experienced a maximum post-void residual (PVR) urine volume ≥200 mL following BOTOX injection compared to those with a maximum PVR <200 mL following BOTOX injection, 44% versus 23%, respectively. No change was observed in the overall safety profile with repeat dosing during an open-label, uncontrolled extension trial.
In detrusor overactivity associated with neurologic condition patients with analyzed specimens in the drug development program (including the open-label extension study), neutralizing antibodies developed in 3 of 300 patients (1.0%) after receiving only BOTOX 200 Unit doses and 5 of 258 patients (1.9%) after receiving at least one 300 Unit dose. Following development of neutralizing antibodies in these 8 patients, 4 continued to experience clinical benefit, 2 did not experience clinical benefit, and the effect on the response to BOTOX in the remaining 2 patients is not known.
The needle should be inserted approximately 2 mm into the detrusor, and 30 injections of 1 mL (~6.7 Units) each (total volume of 30 mL) should be spaced approximately 1 cm apart (see Figure 1). For the final injection, approximately 1 mL of sterile normal s aline should be injected so that the remaining BOTOX in the needle is delivered to the bladder. After the injections are given, the saline used for bladder wall visualization should be drained. The patient should be observed for at least 30 minutes post -injection.

The recommended dose is 50 Units per axilla. The hyperhidrotic area to be injected should be defined using standard staining techniques, e.g., Minor's Iodine-Starch Test. The recommended dilution is 100 Units/4 mL with 0.9% preservative -free sterile saline (see Table 1). Using a sterile 30 gauge needle, 50 Units of BOTOX (2 mL) is injected intradermally in 0.1 to 0.2 mL aliquots to each axilla evenly distributed in multiple sites (10-15) approximately 1-2 cm apart.
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.
Before I could try Botox, my health insurance — Cigna — required me to try and fail at least two other meds. I tried tricyclic antidepressants, which made me groggy and turned my brain into molasses, and beta blockers, a class of drugs used for high blood pressure and heart problems. (All treatments to prevent migraines are borrowed from other conditions, except a new class of drugs that was just approved by the Food and Drug Administration.) The beta blockers worked for a few months: they slightly reduced the number of migraines and made the headaches more bearable. But late last year, the migraines became chronic again — I had more than 15 in a month. That’s when my neurologist said: “I think it’s time to try Botox.”
"Botox is a toxin that is extracted from a certain bacteria. It's been used for a couple of hundred years in medicine. It was first used in neurological conditions rather than cosmetic ones. It was first approved to treat spasms of the face and eye muscles. Only later was it discovered coincidentally that it could world for cosmetic purposes, like wrinkles," he says.
Safety and effectiveness of BOTOX® have not been established for the treatment of other upper or lower limb muscle groups or for the treatment of spasticity in pediatric patients under age 18 years. BOTOX® has not been shown to improve upper extremity functional abilities, or range of motion at a joint affected by a fixed contracture. Treatment with BOTOX® is not intended to substitute for usual standard of care rehabilitation regimens.
There has not been a confirmed serious case of spread of toxin effect away from the injection site when BOTOX® has been used at the recommended dose to treat chronic migraine, severe underarm sweating, blepharospasm, strabismus, or when BOTOX® Cosmetic has been used at the recommended dose to treat frown lines, crow’s feet lines, and/or forehead lines.