In summer, the number of clients in the clinic who want shoulder botulinum toxin rises noticeably.
Because people nowadays sit for long periods or scroll on their phones for hours, the upper trapezius becomes overdeveloped. This makes the neck look shorter and the shoulder line less graceful, which doesn't look good in backless outfits.
However, in the era before ultrasound-guided injection, it was hard to accurately assess how thick each person's subcutaneous fat was by "looking" or "palpating."
In addition, the shape of the trapezius actually varies a great deal from person to person. With a slight slip, it is easy to inject botulinum toxin into a muscle that should not be injected. For example, if the deltoid is injected, the client can easily be unable to raise the arm.
Before I explain how I treat with ultrasound guidance, let's first understand how shoulder botulinum toxin works!
Key Index
Key Index
- What does shoulder botulinum toxin do?
- How many units for shoulder botulinum toxin?
- Shoulder botulinum toxin takes 4 weeks to take effect
- Shoulder botulinum toxin should not be injected in the middle of the spine
- Ultrasound-guided shoulder botulinum toxin injection Mark the area before injecting Identifying the upper trapezius with ultrasound Calculating the needle depth with ultrasound before injecting Tracking the results of shoulder botulinum toxin with ultrasound What to watch for after shoulder botulinum toxin?
What does shoulder botulinum toxin do?
Shoulder injections go into the trapezius
As mentioned earlier, shoulder botulinum toxin needs to be injected into the trapezius.
But if, unfortunately, other muscles are hit, for example the deltoid if too far lateral, or the upper edge of the lung if too far anterior, complications can easily occur.
The deltoid is responsible for "raising the arm." If the botulinum toxin goes too far lateral, it paralyzes the deltoid, so the arm can't be raised.
The uppermost edge of the lung lies toward the front. I have seen newer doctors hold the needle and insert it from in front of the client, which is really quite dangerous. If the needle is inserted from behind, it is very unlikely to injure the lung.
How many units for shoulder botulinum toxin?
The direct answer: the total dose for shoulder botulinum toxin is about 100 to 200 units, with at most 100 units per side for the first session; if the buffalo hump and swan neck are not so severe, 50 units per side is enough.
For shoulder botulinum toxin, the total dose is about 100 to 200 units of botulinum toxin.
For shoulder botulinum toxin, the first session is at most 100 units per side. For people whose buffalo hump and swan neck are not so severe, 50 units per side is enough!
| Masseter | Shoulder botulinum toxin | Calf botulinum toxin | |
|---|---|---|---|
| Muscle treated | Masseter | Upper trapezius | Gastrocnemius |
| Recommended first dose (both sides combined) | 40 ~ 80 U | 120 ~ 200 U | 200 ~ 400 U |
| Time to take effect | 3~4 weeks | 3~4 weeks | 3~4 weeks |
Shoulder botulinum toxin compared with botulinum toxin in other areas
Shoulder botulinum toxin takes 4 weeks to take effect
In the chart below, we can see the thickness of the upper trapezius, as a proportion of its thickness before shoulder botulinum toxin, at 4, 12, 20, 28, 36 and 44 weeks after the injection.
We can see that it is most effective after 12 weeks, but if you don't come back for a top-up of shoulder botulinum toxin after 12 weeks, the thickness of the upper trapezius slowly returns.
So at my clinic, for people who have had shoulder botulinum toxin, I usually ask them to come back after 3 months for a second dose, to extend the effect of the shoulder botulinum toxin.
Shoulder botulinum toxin should not be injected in the middle of the spine
Botulinum toxin can improve the trapezius, but if the thickening is right in the middle of the shoulders, it is very likely not muscle but what is commonly called a "widow's hump."
A widow's hump is actually "thickened fat" in that area. For this reason, thickening in the middle should be treated together with fat-dissolving injections, and cannot be treated with botulinum toxin alone, otherwise the results will be poor.
Ultrasound-guided shoulder botulinum toxin injection
In the past, before ultrasound, the biggest risk with shoulder botulinum toxin was accidentally injecting the neighboring deltoid, the deeper levator scapulae, and so on.
Once these areas are injected by mistake, the client can easily have difficulty raising the arm in the short term, or feel weakness in the shoulder when carrying a bag.
But since ultrasound appeared, because it can accurately show the depth and thickness of the upper trapezius and precisely record the treatment results, the problems above are greatly resolved.
Mark the area before injecting
First, we find three reference points: the seventh cervical vertebra, the spinous process just below it, and the point of the shoulder.
The botulinum toxin is injected along the line drawn between the seventh cervical vertebra and the shoulder. Pay special attention that the outer one-third must not be injected, because the deltoid could be accidentally injured.
Identifying the upper trapezius with ultrasound
Under ultrasound, we can see that the muscles of the back are not just the one piece of upper trapezius. The back actually has several muscles, some deep and some superficial.
The superficial muscles include the upper trapezius, which is the area where shoulder botulinum toxin is injected.
The deep muscles include the levator scapulae, the erector spinae, and so on.
Be sure to confirm the position of the upper trapezius before injecting. Although using ultrasound sometimes takes more time, it is much more precise and reassuring.
Calculating the needle depth with ultrasound before injecting
Under ultrasound, we can go a step further and use the "needle tip enhancement" function to see the needle tip more clearly during injection. This is of great help for people whose trapezius has an unusual shape.
Tracking the results of shoulder botulinum toxin with ultrasound
When the client comes back after 3 months, we can use ultrasound or a measuring tape to track whether the size of the upper trapezius has changed significantly.
Without a special medical condition, the upper trapezius usually changes significantly. In that case the second dose does not need to be as large as the first, and only about 50~70% is needed.
In the image below, we can see that between before injection (left) and 12 weeks after injection (right), the upper trapezius is about 12~15% smaller.
What to watch for after shoulder botulinum toxin?
First, after botulinum toxin is injected into large muscle groups, you will feel sore for the first 1~2 days (because after all, a fair volume of normal saline has been injected into the muscle).
But because normal saline is naturally absorbed by the body, you will hardly feel anything after 3 days.
In addition, botulinum toxin for large muscle groups (shoulders, masseter, calves) is very different from botulinum toxin for forehead lines and frown lines in that large-muscle treatments usually take 4 weeks to take effect.
Conversely, because the forehead lines/frown lines involve small muscle groups, they usually take effect in about 7 days. So if you don't clearly feel your shoulders slimming after 1 week, that is completely normal! Please keep waiting patiently until 4 weeks, when the botulinum toxin will gradually start to work!
FAQ
How long does shoulder botulinum toxin take to work?
Botulinum toxin for large muscle groups usually takes 4 weeks to take effect, very different from forehead lines and frown lines, which take effect in about 7 days. If you don't clearly feel your shoulders slimming after 1 week, that is completely normal. Please wait patiently until 4 weeks, when the botulinum toxin will gradually start to work.
How long do the results of shoulder botulinum toxin last? Do I need a top-up?
It is most effective after 12 weeks, but if you don't come back for a top-up after 12 weeks, the thickness of the upper trapezius slowly returns, so I usually ask clients to come back after 3 months for a second dose, to extend the effect of the shoulder botulinum toxin.
Will I feel uncomfortable after shoulder botulinum toxin?
You will feel sore for the first 1~2 days, because a fair volume of normal saline has been injected into the muscle; the normal saline is naturally absorbed by the body, and you will hardly feel anything after 3 days.
What happens if shoulder botulinum toxin is injected in the wrong place?
If it goes too far lateral and hits the deltoid, the deltoid is paralyzed and the arm can't be raised; if it goes too far anterior, the upper edge of the lung may be injured. If the needle is inserted from behind, it is very unlikely to injure the lung, and I also use ultrasound to confirm the position of the upper trapezius before injecting.
Can botulinum toxin be used for thickening in the middle of the shoulders?
Thickening in the middle of the shoulders is very likely not muscle but what is commonly called a widow's hump, which is thickened fat and should be treated together with fat-dissolving injections. It cannot be treated with botulinum toxin alone, otherwise the results will be poor.
Should the second dose be the same amount as the first?
Usually not. If the upper trapezius has changed significantly, the second dose does not need to be as large as the first, and only about 50~70% is needed.
