Treating the Deep Pyriform Space

The perialar region is notoriously known for being a high-risk zone with regards to soft tissue augmentation. The deep pyriform space is a relatively overlooked treatment area and was only well-described in detail a few years ago.¹

In 2008, Rohrich et al. termed a space medial and deep to the deep medial fat compartment as ‘Ristow’s space’.² In 2016, Surek et al. described the anatomical boundaries of this space in more detail and proposed a name change to the deep pyriform space for anatomical continuity with other named potential spaces in the face, such as the prezygomatic and premaxillary spaces.¹ In this article, I will share my own experience and injection technique for volumising the deep pyriform space and will explore the anatomy, presenting complaints, injection strategy and challenges posed when treating the space.

Anatomical considerations

The deep pyriform space is an inverted triangular-shaped space bound inferomedially by the depressor septi nasi, the soft tissue insertions on the bony pyriform aperture and post-orbicularis oris fat. It is bound laterally and superficially by the deep medial cheek fat and lip elevators.¹ Pneumatisation of this space in cadaveric studies has demonstrated a cephalic extension to the level of the tear trough ligament.¹

The angular artery courses lateral and superficial to the deep pyriform space within a septum, between the space and the deep medial cheek fat at this level.^1,3 This is an important consideration when deciding on the injection depth as we want to be in a deep plane to avoid the angular artery. The infraorbital foramen lies superolateral to the angular artery in this region and, in 57% of cases, the infraorbital artery shares the same supplying territory or anastomoses with the angular artery. This is compared to the other 45%, which show no connection to the angular artery in 284 cases.⁴ Practitioners should be aware that there are variations in vasculature especially with the branches of the facial artery, but this is beyond the scope of this article.⁵

Presenting ageing complaints

The treatment indication for volumising the deep pyriform space is due to having a depression or hollowing in the perialar region caused by maxillary bone retrusion.¹ In addition, this bony retrusion also contributes to the formation of nasolabial folds.^6,7

We know that maxillary retrusion is part of the ageing process and bony changes invariably have an impact on overlying soft tissues.^6,8 This is compounded by soft tissue ageing itself such as hypertrophy of the superficial nasolabial fat compartment.⁹

I will also point out that in my practice, where I treat a significant number of East Asian patients, I perform many deep pyriform space volumisation treatments in much younger patients. This is due to the inherent structural bony differences of the demographic when compared to Caucasians. In general, the maxillary bone is more retruded in East Asians and perialar recession, associated with early nasolabial folds, is a common presentation in this group of patients, as early as in their 20s.¹⁰ I describe the differences between the aesthetic ideals of Asian vs. Caucasian patients in my previous article published in the Aesthetics journal.¹¹

Not only can volumising the deep pyriform fossa improve perialar recession and nasolabial folds, it can also enhance the three-dimensional profile of the mid-face.¹⁰

Injection technique

I prefer to use a hyaluronic acid filler with a high G prime for two main reasons. The first being that this offers the best lift capacity to help volumise the overlying tissues; secondly, it ensures the product will stay in place which is important as this region is highly dynamic.

I prefer to use a needle over a cannula as I want to be able to place an accurate bolus directly onto the bone, which I feel is better achieved with a needle. I approach the skin with the needle from lateral to medial so that I am perpendicular to the nasolabial line.

 Alternatively, you can aim in the direction of the contralateral oral commissure for guidance.

I ensure the bevel is facing down and angle the needle as low as possible (ideally 10 degrees). A study in 2019 showed that injecting at an angle of 10 degrees with the bevel down reduces uncontrolled product distribution into superficial fascial layers. The study also mentions that using a 30 gauge needle helps in reducing spread, but that the angle of injection seems to have a greater influence on precision than it does needle size.¹² My preference is to use a 27 gauge needle, however, as I find it easier to inject a high G prime filler as the extrusion force needed is lower.

I like to pull the nasolabial fat superolaterally with my non-injecting hand before I enter with the needle. Once I am happy that I am on the bone I free my non-injecting hand and proceed to aspirate before injecting. There is debate regarding aspiration as a safety manoeuvre especially due to false negative results.^12,13 Whilst there is no conclusive study on whether to aspirate or not, even in the pyriform fossa, for such a precarious treatment zone I personally feel the need to aspirate. This may change over time and will depend on an evidence-based approach. The product is injected very slowly as a bolus and I always ensure I am deep onto the bony pyriform aperture to avoid the angular artery, which is superficial to the deep pyriform space.¹ You will be able to see the gradual volumisation of the region as you are injecting. In addition, whilst you are injecting you should observe the whole face for any signs of vascular occlusion such as pain, blanching and delayed capillary refill time.¹⁴ It is highly advisable to use no more than 0.3ml of a high G prime filler on each side to reduce the risk of vascular compression (Figure 2).

Treatment challenges

In my opinion, I think the biggest challenge in treating the deep pyriform space is ensuring accurate product placement without uncontrolled product spread. I have noticed that I do not get the same level of volumisation and therefore optimal aesthetic outcome if the needle is not touching the bone before I inject. It can be difficult to hit the bone if you are approaching from a very low angle of injection as I suggested above, but I believe this comes with practice and confidence.

If your product is injected too superiorly then there is a higher risk of compression or occlusion of the infraorbital artery.^4,15 If your product is injected too low (inferior to the nasal alar) then there is a chance that it may be deposited in the alveolar mucosa. To avoid these two scenarios, I ensure that the end of my needle is parallel with the widest point of the nasal alar.

After treating the deep pyriform space, there may be a residual nasolabial fold and you can treat this accordingly to optimise the aesthetic outcome for mid-face rejuvenation (Figure 3).

Conclusion

Whilst the deep pyriform space is a fairly recently described anatomic space, its significance as an important target for mid-face volumisation is unquestionable. One should appreciate the latest publications on the regional anatomy to ensure maximum safety and confidence when treating this area. There are various injection techniques for treating the space but, in my experience, the technique I have described has yielded a high level of patient satisfaction and safety profile.

I will also stress that treatment of this space is just one aspect that contributes to optimal aesthetic mid-face rejuvenation and it is important to take into consideration other mid-facial regions such as the medial and lateral cheeks. Ultimately, I believe it is highly advantageous for aesthetic practitioners to appreciate that this space exists and, if treated correctly, can demonstrate excellent aesthetic outcomes.