When Hyalase Doesn't Work - What Ultrasound Reveals

Dr Ng Zhi Yang
6 days ago
5 min read

Updated: 5 days ago

Filler issues are more common than the aesthetic industry acknowledges. Most are managed clinically - by eye, by feel, and by protocol. Below are cases that I have assessed recently. They illustrate why point-of-care ultrasound (POCUS) changes what is possible, both in understanding what is actually present, and in planning what can be done next.

Case 1 - Aquamid in the Radix: A Permanent Filler and Its Consequences

A patient presented with a widened nasal radix. This is sometimes described as an "Avatar nose." The history: Aquamid, a polyacrylamide hydrogel filler, had been injected into the radix by a local aesthetic doctor, more than ten years ago.

Aquamid is NOT hyaluronic acid so it CANNOT be dissolved with hyalase. It integrates with the surrounding tissues over time and therein lies the problem - it becomes PERMANENT. What looks like a contained filler deposit in the early months becomes, over years, a material that has spread beyond its original placement zone and interdigitated with the surrounding soft tissue. The "Avatar" appearance, a wide, flat, and unnatural-looking radix, is most likely the clinical consequence of a permanent filler that has migrated and settled in ways that cannot be predicted or controlled.

A POCUS scan showed a large hypoechoic deposit beneath the skin surface with irregular, ill-defined borders, consistent with Aquamid that has spread and integrated into the surrounding tissues over more than a decade (see below). There is no sharp boundary, no discrete capsule, and hence, no clean margin for surgical removal.

Aquamid filler on POCUS - ZNG Plastic Surgery, Singapore — POCUS scan of the radix in a patient, showing a large, indistinct, hypoechoic mass consistent with the history of Aquamid.

By the time she came to me, both hyalase (aka hyaluronidase) injections and needle aspiration had already been attempted. Neither made any meaningful difference, and this is entirely predictable. Aquamid (polyacrylamide hydrogel) is NOT a hyaluronic acid filler and is therefore, NOT amenable to dissolution with hyalase/hyaluronidase. It reflects a fundamental misunderstanding of the material by the treating doctor.

Management is very difficult and must be honest with the patient. A stab incision with suction can be attempted, but given the degree of integration over more than ten years, this method is unlikely to work, especially when needle aspiration had already been attempted. The only realistic option left is surgery, through a rhinoplasty approach, to physically scrape and remove/debulk the material, with the acceptance that complete removal is most probably not achievable. Notwithstanding, the surgery itself also carries the inherent risks of a revision rhinoplasty in what is essentially a compromised soft tissue environment.

This IS the endpoint of permanent filler in the nose. It is why I DO NOT use it, recommend it, or offer it. A result that looks acceptable at one year can look like this at year ten.

Case 2 - Tear Trough Filler That Would Not Dissolve

A patient presented with a "sausage roll" appearance just above the tear trough - a palpable, visible ridge beneath the lower eyelid that had not responded to two to three rounds of hyalase. Tear trough filler had been placed by the same aesthetic doctor about five years ago.

On clinical examination alone, it was impossible to know why hyalase was not working. Was the filler material simply resistant due to cross-linking, had it become encapsulated in fibrous tissue, or was the hyalase not reaching the filler deposit at the right depth?

POCUS helped shed some light on possible reasons. The scan showed a well-defined, echogenic deposit measuring 10.85 mm long in the tear trough area, right on the bone (supra-periosteal placement), with evidence of layering and organisation (see below). This appearance is consistent with filler that has become encapsulated or fibrosed over time, and explains its resistance to hyalase/hyaluronidase. If the filler was surrounded by a fibrous capsule, the hyalase/hyaluronidase is unlikely to penetrate it effectively, regardless of how many times it was injected around the area, or at what dose. This we can see on POCUS, as there appears to partial, irregular encapsulation (see below). On this note, such "blind" attempts at injecting hyalase can lead to what's known as posthyaluronidase syndrome with further hollowing.

Persistent tear trough filler despite hyalase - ZNG Plastic Surgery, Singapore — POCUS scan showing filler placed in the supra-perisoteal plane, measuring approximately 10.85 mm across. However, note the irregularity of its contours (see yellow arrow) in the picture on the right, which is consistent with the history of unsuccessful hyalase attempts and likely encapsulation/fibrosis, which would be in keeping with the use of a HA filler with BDDE.

The filler in this case, was most likely a hyaluronic acid (HA) product using Butanediol Diglycidyl Ether (BDDE) cross-linking technology, a formulation associated with significantly greater resistance to hyalase/hyaluronidase. This is not a minor clinical footnote. A class action lawsuit filed in June 2024 against AbbVie in the United States District Court for the Northern District of Illinois specifically highlights BDDE as pro-inflammatory, citing scientific literature describing the combination of BDDE and HA as capable of triggering delayed granuloma formation.

A patient who was told her filler could always be reversed with hyalase, and who is now on her third failed dissolving attempt five years later, is living that consequence.

The management plan in this case is ultrasound-guided hyalase/hyaluronidase, under direct real-time visualisation, to ensure it is placed at the exact depth of the filler deposit rather than in the surrounding tissue. My colleagues and I published on the superiority of this approach in 2025, through a systematic review and pilot meta-analysis, compared to "blind" landmark injection for filler complications. Following successful dissolution, the next steps would be fat grafting for volume restoration and nanofat for skin quality improvement in the tear trough area.

Why POCUS Changes the Management of Filler Complications

These cases illustrate the same principle, that clinical examination alone only tells you there IS a problem. POCUS however, tells you WHAT the problem might actually be - the nature of the material, its depth, its distribution, and why standard treatment may not be working. Without imaging, management is empirical; with imaging, it is informed.

In the Aquamid case, POCUS confirmed that the filler had integrated beyond the reach of minimally invasive removal - a finding that changes the entire surgical conversation. In the tear trough case, POCUS explained why multiple rounds of hyalase had failed and pointed directly to the solution.

As filler use continues and long-term complications become increasingly common, the argument for POCUS as a routine assessment tool in filler complication management becomes stronger. These cases are not outliers. They are what happens when fillers are placed without long-term consequence in mind, and what is required to manage them, if at all possible.

Written by Dr Ng Zhi Yang, UK & Singapore accredited Plastic Surgeon. Winner of ISAPS Bronze Medal for Rhinoplasty (2025), and Best Abstract Award (2024) at the London Rhinoplasty Course, Techniques in Rhinoplasty with an Integrated ENT-Plastics Approach.

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