Characterization of temporal soft tissue space to aid the design of implants aimed at restoring function in facial paralysis

Abstract

Aim: Facial paralysis inflicts devastating functional and aesthetic deficits. Several solutions are being developed, including implantable bionics to correct paralytic lagophthalmos. The temporal fossa has been postulated to be a suitable location for such devices. Anatomical studies of this fossa have limited application in the design of implants with complex internal components that are constrained by specific functional requirements. In this study, we assess the variation in temporal fossa volumes that could be utilized by a functional implantable device.

Methods: CT scans of 18 hemifaces were used to create a 10-point template for measuring tissue thickness in the temporal fossa. Using this data, linear models were used to perform a volumetric analysis of the temporalis muscle and temporal fat pad concerning key anatomical landmarks.

Results: The estimated temporalis muscle, temporal fat, and total combined volumes were 19.2 mL (95%CI: 10.4-32.9), 10.3 mL (95%CI: 6.1-16.1), and 29.5 mL (95%CI: 16.7-48.9) respectively, consistent with other publications. The temporalis muscle volume increases rapidly and then plateaus moving posteriorly along the zygomatic arch and superiorly along the lateral orbital rim. Whereas the temporal fat increases similarly along the lateral orbital rim, it increases at a uniform rate along the zygomatic arch.

Conclusion: Simple geometric modelling of the functional soft tissue space in the temporal fossa is feasible and can be readily applied to aid in the development of implantable devices.

Keywords

Blink / facial palsy / prosthesis / reanimation / eyelid

References

[1] Jowett N,Knox CJ.Toward the bionic face: a novel neuroprosthetic device paradigm for facial reanimation consisting of neural blockade and functional electrical stimulation..Plast Reconstr Surg2019;143:62e-76e PMCID:PMC6311722

[2] Tollefson TT.Restoration of eyelid closure in facial paralysis using artificial muscle: preliminary cadaveric analysis..Laryngoscope2007;117:1907-11

[3] Hasmat S,Suaning GJ,Clark J.Restoration of eye closure in facial paralysis using implantable electromagnetic actuator..J Plast Reconstr Aesthet Surg2016;69:1521-5

[4] Foirest C,Gatignol P.Smile reanimation after unilateral facial palsy by lengthening temporalis myoplasty: objective and subjective evaluation on 25 cases..Plast Reconstr Surg2017;139:984e-93e

[5] Stephan CN.The superficial temporal fat pad and its ramifications for temporalis muscle construction in facial approximation..Forensic Sci Int2009;191:70-9

[6] Zhao Y,Perry JD.Comparison of temporal fossa volume in young versus senescent human skulls..Ophthalmic Plast Reconstr Surg2015;31:482-5

[7] Rinkinen J,Beauregard J.Morphomic analysis as an aid for preoperative risk stratification in patients undergoing major head and neck cancer surgery..J Surg Res2015;194:177-84 PMCID:PMC4823149

[8] Ranganathan K,Lisiecki J.Temporalis muscle morphomics: the psoas of the craniofacial skeleton..J Surg Res2014;186:246-52

[9] Furtner J,Gorlia T.Temporal muscle thickness is an independent prognostic marker in patients with progressive glioblastoma: translational imaging analysis of the EORTC 26101 trial..Neuro Oncol2019;21:1587-94 PMCID:PMC6917403

[10] Kim JH,Shin CH,Han YS.Temporal augmentation with calvarial onlay graft during pterional craniotomy for prevention of temporal hollowing..Arch Craniofac Surg2018;19:94-101 PMCID:PMC6057125

[11] Huang RL,Wang W,Li Q.Long-term outcomes of temporal hollowing augmentation by targeted volume restoration of fat compartments in chinese adults..JAMA Facial Plast Surg2018;20:387-93 PMCID:PMC6233616

[12] Cervelli D,Grussu F.Autologous fat transplantation for the temporalis muscle flap donor site: our experience with 45 cases..Head Neck2014;36:1296-304

[13] Volk GF,Klingner CM,Guntinas-Lichius O.Quantitative magnetic resonance imaging volumetry of facial muscles in healthy patients with facial palsy..Plast Reconstr Surg Glob Open2014;2:e173 PMCID:PMC4174245

[14] Senders CW,Curtiss S,Prahlad H.Force requirements for artificial muscle to create an eyelid blink with eyelid sling..Arch Facial Plast Surg2010;12:30-6

[15] Kim S.The anatomy of temporal hollowing: the superficial temporal fat pad..J Craniofac Surg2005;16:651-4

[16] Furtner J,Schöpf V.Temporal muscle thickness is an independent prognostic marker in melanoma patients with newly diagnosed brain metastases..J Neurooncol2018;140:173-8 PMCID:PMC6182383

[17] Goto TK,Nakamura Y.Volume changes in human masticatory muscles between jaw closing and opening..J Dent Res2002;81:428-32

[18] Rezaeitabar Y.Automatic 3D segmentation of individual facial muscles using unlabeled prior information..Int J Comput Assist Radiol Surg2012;7:35-41