Anatomy & Cell Biology· 2026Q2· Case report
Deep-plane paradoxical masseteric bulging after dual-plane botulinum neurotoxin injection: a case report
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- Q2SCImago
- 2026year
Short summary
A case report reveals deep-plane paradoxical masseteric bulging (PMB) originating from the inner functional compartment of the superficial masseter layer, despite dual-plane botulinum neurotoxin type A injection.
AI-generated from the title and abstract; the full text is not read.
Key points
- Paradoxical masseteric bulging (PMB) can originate from the inner compartment of the superficial masseter layer, even after dual-plane botulinum neurotoxin injection.
- Dynamic ultrasonography revealed outer sub-layer paralysis and paradoxical thinning, contrasted with marked compensatory thickening of the inner sub-layer.
- A distinct internal aponeurosis separates these functional compartments within the superficial masseter.
- Targeted deep-plane reinjection under ultrasound guidance successfully resolved the PMB.
AI-generated from the title and abstract; the full text is not read.
Abstract
Paradoxical masseteric bulging (PMB) is a distressing complication typically attributed to compensatory contraction of untreated superficial muscle fibers. However, the anatomical mechanism of bulging that occurs despite dual-plane injection remains poorly defined. We report a case of deep-plane paradoxical compensatory masseteric bulging in which the protrusion originated from the inner functional compartment of the superficial layer of the masseter muscle following planned dual-plane botulinum neurotoxin type A injection. Dynamic ultrasonography demonstrated complete paralysis of the outer sub-layer with paradoxical thinning during clenching, while the inner sub-layer exhibited marked compensatory thickening beneath a distinct internal aponeurosis. Targeted deep-plane reinjection under ultrasound guidance resulted in complete resolution. This case highlights the compartmentalized anatomy of the masseter muscle and emphasizes the importance of anatomical and sonographic evaluation in refractory PMB.
The authors' abstract, as published at the source. Anatomy & Cell Biology, 2026 · DOI ↗
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Field: Neurology (Medicine)
NeurologyMedicine