Connection Between Botox and MND

Botox does not damage the nerve that travels in the spine. Botox merely acts as a physical blocker in the space between the end of the nerve and the muscle. It prevents the terminal section of the nerve from transmitting the signal to the muscle to contract. When the Botox wears off, which it always does, the nerve ending can send the signal again and the muscle contracts. The nerve does not get permanently impaired.

Leighton,
NMDs are not caused by Botox. I think the concern is that if you already have a NMD, then Botox may potentiate any manifestation of the disease since the neuromuscular transmission is already affected by the disease. However Botox is not causing the disease and is not worsening the disease in any way.

Leighton,
There is absolutely no evidence that Botulinum Toxin A (BOTOX, Allergan, Inc, Irvine, CA) triggers Motor Neurone Disease. Motor Neurone Disease (MND) is a group of disease that are commonly referred to as ALS or Lou Gehrigs disease. It is in fact not clear what tiggers these conditions, although there is expanding information on the genetics of MND/ALS. The disease presents with progressive muscle atrophy, weakness, fasiculation or twitching and is assoicated with atrophy and cell loss in the ventral horns of the spine and corresponding loss of neurons in the brain. Emotional fluctuations and pathological laughter can be seen and this is referred to as a pseudobulbar palsy.
BOTOX has been used to treat symptoms associate with MND and in this specific setting, some individuals can experience unwanted side effects of treatment related to the treatment. However, this is not the same thing and BOTOX causing their MND.
Generally, it is advisable to avoid BOTOX cosmetic if there is a history of a neuromuscluar dengenerative illness. BOTOX may be recommended by a neurologist experienced with its use in these conditions to improve some of the symptoms of MND but this should not be confused with receiving BOTOX for cosmetic purposes. One has nothing to do with the other.

Leighton,
If it is known that a neurologic condition or disease is present, then it is probably best not to use Botox Cosmetic. What may occur more commonly is that a patient that has a previously undiagnosed or subclinical neurologic condition becomes unmasked when Botox is used for cosmetic reasons. The Botox does not trigger the disease, it merely unmasks it and may lead to an earlier diagnosis than would otherwise have occurred.

Motor neuron diseases are conditions in which degeneration of the nerves that stimulate muscles to contract are affected. An example of this is Lou Gehrig's disease. Neuromuscular diseases including Lou Gehrig's disease, Myasthenia Gravis and Eaton-Lambert syndrome are contraindications to using Botox, but to my knowledge, have not been triggered by Botox.