How to avoid unwanted dynamic effects (new lines) from Botox treatment

When things go wrong with an aesthetic treatment, it can be categorised as one of two outcomes – a complication or an unwanted effect. Naturally, we want to practise to avoid causing complications by mitigating known risks because these are often the most serious, complex, or distressing for your patient. Complications should be rare; however, unwanted dynamic effects caused by undertreatment or overtreatment can be more commonplace and is another area where understanding of underlying anatomy can explain why they occur and how to avoid their occurrence.

In this blog, Dr Tim Pearce will discuss some unwanted effects of Botox treatment around the eye, including bunny lines and under-eye lines, touching on the anatomy involved so you can learn to inject more confidently.

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Why can bunny lines occur after botulinum toxin treatment?

One dynamic unwanted result you might experience from Botox treatment is an increase in lines on the bridge of the nose, often called bunny lines, that can occur after treatment targeted at the glabella (for frown lines) or the orbicularis oculi (for treating crow’s feet).

This phenomenon happens because we tend to be only treating a segment of the muscle – for example, the bottom lateral quadrant of the orbicularis oculi – hence activity is reduced in one area of the face, but untreated areas remain and can activate, causing a decrease in tone in the treated area, but an increase in resting tone in untreated areas.

Small wrinkles may develop on the bridge of the nose, an area previously free of lines, due to muscle activity in that region.There is some debate concerning which muscles are responsible. Reviewing the anatomy, we note several muscles that could be contributing to the formation of bunny lines around the bridge of the nose.

The superficial component of the orbicularis oculi muscle

A likely contender for involvement because it is a small area of the orbicularis oculi muscle, a round muscle, that slightly overlaps on the nose. The muscle is superficial at this point, located directly in the region of line formation, and certainly capable of creating tiny lines.

The levator labii superioris alaeque nasi muscle

The levator labii superioris alaeque nasi muscle runs along the side of the nose and is responsible for pulling the lip upwards. This muscle has a branch that goes all the way up the nose and crosses the area where bunny lines manifest. Activity is increased in this muscle after treatment of orbicularis oculi, perhaps because there is a similar nerve supply that could be contributing to activity.

The nasalis muscle

The nasalis muscle is bigger, attached to the bone, and pulls the nose inwards. In some patients, it could also be contributing to bunny line formation. There is perhaps an overlap of impact from all three named muscles in some cases.

How to avoid causing bunny lines when treating the upper face with botulinum toxin

Remember, this is not a complication per se, but an unwanted dynamic effect. When considering how to treat or correct, we must assess the totality of facial movement which should demonstrate low activity, laterally, and high or too much activity, medially. The solution is to inject botulinum toxin into the overactive area. The safest way to achieve this is by being very superficial, using a low dose, and staying away from the lip elevator muscles.

We must not purposely treat levator labii superioris alaeque nasi or any of the medial cheek muscles, instead only affecting the superficial muscle that is causing a line on the bridge of the nose, which is most consistent with orbicularis oculi. Superficially place two (Botox) units with the bevel facing up to resolve in most patients.

Learn more about how to avoid accentuating bunny lines and other best-tried and tested Botox injection patterns and mistakes to avoid.

Why can under-eye lines occur after botulinum toxin treatment?

Under-eye lines are a similarly unwanted dynamic effect that can occur when treating around the eye area with botulinum toxin.

This is not the same as causing an ectropion eyelid but is a little similar to the ledge problem described in a previous blog on how to avoid lacrimal gland compromise and dry eye from Botox treatment.

This effect results in a line that runs along the underneath of the eye when the cheek raises during a smile. It is caused by a combination of the cheeks moving upwards and a decrease in skin tightness when the lateral eye contracts.

Following a normal treatment for lateral canthal lines (crow’s feet), which removes the lines in the average patient, a new line can sometimes form underneath the eye due to the unknown contribution made by the orbicularis oculi muscle to pull the skin tightly under the eye.

When you smile tightly, the skin under your eye is pulled away, and the cheek rises smoothly, due to lateral canthal (orbicularis oculi) muscle contraction. If this contraction is inhibited with botulinum toxin, more skin is in the path of the rising cheek and can be compressed to create a new line.

This effect is uncommon, and it is certainly difficult to predict the likelihood of occurrence. The only known solution is to avoid injecting, particularly at the lowest injection point (when treating the crow’s feet) to allow for more natural muscle activity. Beyond that, there are limited treatment options unless the individual requires tear-trough treatment, which most do not.

How to avoid causing under-eye lines when treating the upper face with botulinum toxin

This unwanted dynamic effect cannot be resolved, beyond letting it wear off, so prevention and a conservative approach to treatment is the best way to mitigate occurrences for all patients, particularly with the lowest injection point during lateral canthal line treatment.

Most aesthetic clinicians are rightly led by the licensed doses (in this case, four-four-four at three points for Botox); however, for all new patients, you may prefer to follow a lower dose approach at the lower injection point, using two units. This will avoid the unwanted effects, and your decision to maintain or increase the dose at that point can be reviewed concerning future treatment.

Learn more about facial muscle anatomy for Botox in 10 minutes.

Check out some other recent blogs from Dr Tim, exploring potential side effects related to Botox treatments around the eye area.

• How to avoid causing eyelid ptosis with botulinum toxin treatments
• How to avoid lateral rectus palsy and double vision from Botox treatment

If you have any questions or topics for discussion, you can find Dr Tim Pearce on Instagram.

Botox® is a registered trademark of Allergan Aesthetics plc.

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