Injectable corticosteroid preparations: an embolic risk assessment by static and dynamic microscopic analysis

Area of Science:

• Neurology
• Pharmacology
• Interventional Radiology

Background:

• Transforaminal corticosteroid (CS) injections are linked to severe central nervous system (CNS) adverse events, including infarction.
• The embolic potential of CS preparations during transforaminal injection is a significant concern.

Purpose of the Study:

• To microscopically analyze static and dynamic appearances of CS preparations.
• To evaluate the embolic potential of CSs in transforaminal injections, focusing on CNS adverse events.

Main Methods:

• Examined pharmaceutical preparations of methylprednisolone acetate (MPA), triamcinolone acetonide (TA), and dexamethasone sodium phosphate (DSP).
• Utilized dynamic imaging to simulate crystal flow in spinal cord arterioles.
• Assessed crystal aggregation and size changes after mixing with plasma.

Main Results:

• MPA and TA contain crystals (MPA: 0.4-26 μm; TA: 0.5-110 μm), while DSP is essentially free of significant crystals.
• CS crystals maintained integrity and aggregation potential, acting as emboli in dynamic imaging.
• Mixing with plasma reduced aggregate size but not integrity.

Conclusions:

• Inadvertent intra-arterial injection of MPA and TA during TFESI carries a substantial risk of infarction due to embolization.
• Dexamethasone sodium phosphate (DSP) is fully soluble and poses no embolic risk to arterioles.
• Avoid insoluble CSs like MPA and TA during cervical TFESI to prevent adverse CNS events.