Deoxycholic Acid and the Marginal Mandibular Nerve: A Cadaver Study

Area of Science:

• Nerve regeneration and repair
• Histopathology
• Aesthetic medicine

Background:

• Marginal mandibular nerve (MMN) injury is a rare but serious complication of deoxycholic acid injections.
• The direct neurotoxic effects of deoxycholic acid on the MMN are not fully understood.

Purpose of the Study:

• To investigate whether deoxycholic acid directly causes histological damage to fresh cadaveric MMN.
• To evaluate the dose-dependent and time-dependent effects of deoxycholic acid on MMN.

Main Methods:

• MMN segments from human cadavers were exposed to deoxycholic acid (10 mg/ml) for 20 minutes or 24 hours, or to sterile saline.
• Nerve specimens were analyzed using light microscopy with toluidine blue staining and color deconvolution.
• Subplatysmal fat was used as a positive control and examined via transmission electron microscopy.

Main Results:

• Deoxycholic acid exposure resulted in decreased toluidine blue staining in MMN compared to saline controls.
• Longer exposure (24 hours) to deoxycholic acid led to more significant reductions in staining.
• Transmission electron microscopy revealed disruption of adipocyte cell membranes and loss of organelles in fat exposed to deoxycholic acid.

Conclusions:

• Deoxycholic acid (10 mg/ml) directly damages the myelin sheath of the MMN in human cadaver specimens.
• Direct neurotoxicity of deoxycholic acid is a likely mechanism for clinical MMN injury.