Botox: Uses Include Neurological Conditions

Botox: Uses Include Neurological Conditions

Wednesday, October 5, 2022

What is Botox?

Botox is the brand name of a neurotoxin known as OnabotulinumToxin A. This neurotoxin is isolated from the bacteria Clostridium Botulinum and is primarily a paralytic agent. Botox is not found in isolation, rather, there is a group of neurotoxins with similar properties including AbobotulinumToxin A (Dysport), DaxibotulinumToxin A (Daxxify), IncobotulinumToxin A (Xeomin), PrabotulinumToxin A (Jeuveau), and RimabotulinumToxin B (Myobloc).

How does it work?

The understanding of the mechanism of action of Botox begins with the understanding of nerve impulse transmission, a process that involves chemical and electrical changes in the nerve.

Influx of sodium into the nerve cell coupled by the efflux of potassium creates an electrical signal that is propagated down the length of the nerve cell. When the signal arrives to the ending of the nerve, calcium enters. This entry then allows a protein complex made of three so called snare proteins to form. This complex formation results in the fusion of sacs (referred to as vesicles) containing a chemical (called acetylcholine) to merge with the nerve ending membrane. The released acetylcholine then diffuses across a space between the nerve and muscle referred to as the synaptic cleft and then binds its respective receptors on the muscle membrane. This binding results in a similar electrochemical change in the muscle leading to its contraction.

When Botox is injected into a muscle, it is taken up by the nerve ending in communication with that muscle. Then, Botox is broken down into its components: the heavy and light chains. The latter then cleaves the SNAP protein, one of the three snare proteins. In doing so, the vesicles do not fuse with the membrane of the nerve and acetylcholine is not released resulting in absence of muscle contraction and paralysis. The effects of Botox are reversible within 9-12 week.

What is Botox used for?

The neurotoxin Botox is used for various neurological conditions with great efficacy. To name a few, it is used in spasticity, dystonia, certain tremors, tics, migraine headaches, hemifacial spasm, blepharospasm, overactive bladder, and hyperhidrosis (excessive sweating). While it is FDA approved for most of its uses, it is used in an off-label capacity for certain conditions such as trigeminal neuralgia (facial pain syndrome), achalasia (a esophageal dysmotility syndrome), and sialorrhea (drooling). Please find below some definitions of some of these commonly treated conditions.

Blepharospasm: involuntary eye closure disorder.

Dystonia: sustained involuntary muscle contraction that results in abnormal posture, usually in the neck.

Hemifacial spasm: brief and non-sustained facial muscle contractions that result in visible facial twitching.

Tics: involuntary movements that can be isolated to one or several muscles in sequence. Tics can be vocal, and having more than one tic type in addition prior to the age of 18 is referred to as Tourette syndrome.

Spasticity: increased muscle tone resulting in pain and reduced range of motion of a limb. This is typically seen with stroke victims and victims of cerebral palsy.

How is Botox given?

Botox is injected into the target muscles by a Neurologist or a Pain specialist using various needle sizes and various amounts reported in units depending on the indication. The injection is typically done every 12 weeks in a effort to prevent the body from neutralizing the toxin by building antibodies against it. Again, based on indication, it can be injected into the arms/legs, eyelids, other facial muscles, neck muscles, and the bladder.

 Are there side effects?

If the injections are done properly, side effects of Botox are minimal if any at all. Side effects can be either related to the toxin itself or the procedure. Procedural side effects include bleeding, infection, muscle hematoma/trauma, and damage to adjacent structures. There are rare as precautions are often taken to prevent this occurrence.

Toxin related side effects are usually local and related to the injected target. For instance, in the case of migraine or blepharospasm, injections into the eyelid muscles may cause slight drooping of the eyelid. Other potential local side effects of the toxin include double vision, head drop, neck pain, headache, facial droop, and limb weakness. In the case of dystonia, injecting the neck muscles may also result in trouble swallowing. There is a theoretical risk of Botox spreading to distant muscles in which case patients can develop respiratory difficulties. Allergic reactions to Botox are exceedingly rare.

Is Botox for every one?

Patient with a neuromuscular condition called Myasthenia Gravis should not receive Botox injections. In addition, Botox should be used with great caution in patient with other neuromuscular conditions such as ALS. Furthermore, patients who develop an allergic reaction to Botox or some of its components should not receive Botox again.

If you find you may benefit from Botox injections for any of the conditions discussed above, please call the Neurology clinic at 337-374-7242 to make an appointment.