This can be thought of as a "pressure wash" for nerves.
It is commonly performed for the median nerve, in carpal tunnel syndrome, freeing it from the overlying transverse carpal ligament and tendons below. It is best reserved for mild to moderate cases, which an EMG can help diagnose. In a randomized controlled trial in 2019 by Wu and colleagues, published in Muscle and Nerve, it was demonstrated that nerve hydrodissection reliefs pain and increases function at 3 and 6 months.
It involves using a needle, and injecting saline (essentially water), into the soft tissue around the nerve. This separates the two structures physically, so that the mechanical pressure over the nerve is relieved and it can once again glide freely (Evers 2017).
This procedure can also be combined with steroid to help with pain relief.
What are the benefits?
Pain relief and improved function.
What are the alternatives?
Conservative treatment includes activity modification, simple pain meds, and bracing.
In terms of procedures, options include nerve hydrodissection, steroid injection, or a combination of the two. Surgery is the most invasive treatment and is reserved as the last option.
How long will my pain be reduced?
With this procedure and other strategies recommended by your physician, we hope to get complete pain control. In more severe cases, surgery may be necessary.
How often can I have this done?
Nerve hydrodissection with saline can be performed however many times are required, so long as it fits with the patient’s overall goals, lifestyle, and expectations. If steroid is being injected, we are more cautious in this area and rarely do it more than once.
Who can’t have this done?
Any patient who may appear to have:
Infection within the body, near the site of administration, or the actual joint itself
What are the side effects?
Common, but not severe
Pain after injection: If steroid is injected, a post-injection flare occurs in approximately 10% of patients. Like other injections, it usually settles within 2 days. Application of ice and Tylenol can help, if desired.
Pain during the procedure: The skin is the most sensitive part when it comes to any injection. We minimize this by using local anesthetic and/or a vapocoolant spray on the skin. Pain associated with the injection is usually brief and well-tolerated.
Not common, but potentially severe
Infection: When a needle is passed through the skin into the body, there is a very small chance of introducing a joint infection. The chance of this occurring is extremely low, less than 0.002%, or equivalent to being struck by a car as a pedestrian and experiencing a catastrophic event. To minimize this risk, we not only follow the WHO minimum best practice standards for injections, but use sterile gloves, sterile ultrasound probe covers, and sterile ultrasound gel.
Bleeding: This is a greater risk if you have a known bleeding disorder or are taking blood thinners. By using ultrasound guidance, there is less “poking” around to get to the target tissue of interest, and thus less theoretical risk of bleeding. Pressure is maintained over the skin afterwards to reduce bleeding.
Can I drive afterwards?
If you were able to drive to the appointment, most people can drive afterwards. Nonetheless, we ask all patients to remain in the clinic waiting room for a minimum of 15 minutes afterwards to observe for any adverse reactions if steroid was provided.