Abstract ID: A5
Abstract Title: Particle Sizes of the Different Steroids and the Effect of Dilution
Authors: Honorio B1, Teng-Leong C2, Hubert B3, Robert M4
Northwestern University Feinberg School of Medicine Chicago Illinois USA1, Northwestern University Feinberg School of Medicine Chicago Illinois USA2, Northwestern University Feinberg School of Medicine Chicago Illinois USA3, Northwestern University Feinberg School of Medicine Chicago Illinois USA4
Poster Type: Poster
ABSTRACT BODY
Background: Transforaminal epidural steroid injections (TF ESIs) have been recommended to deposit the drug in the anterior epidural space. There have been cases of paraplegia from TF ESIs (1-3). Trauma or occlusion of the segmental artery accompanying the nerve root may result in vascular compromise and segmental infarct of the spinal cord (4,5). The injected steroid may occlude the segmental artery (6). We performed a study wherein we looked at the effect of different dilutions on the particle sizes of the different steroids used in epidural injections.
Materials and Methods: A drop of the undiluted sample was placed on a microscope slide and a cover slip placed immediately. For the diluted samples, a 1-mL aliquot was withdrawn and diluted with either one mL, two mL or 3 mL of 1% lidocaine. The samples were examined with a Zeiss LSM 510 laser scanning confocal microscope and the images were analyzed and measurement performed using the Zeiss LSM software. Measurements were recorded in a spreadsheet program and arranged according to the following particle sizes: a) 0-10; b) 10-20; c) 20-30; d) 30-40; e) 40-50; f) 50-75; g) 75-100; and, h) > 100 microns.
The particle sizes of the following drugs were measured: a) methylprednisolone acetate, 40 mg/mL; b) methylprednisolone acetate, 80 mg/mL; c) triamcinolone acetonide, 40 mg/mL; and, d) dexamethasone sodium phosphate, 4 mg/mL acetate. There is a shortage of betamethasone sodium phosphate/betamethasone acetate and we were not able to study the drug. We used nonparametric and nonparametric statistical techniques as appropriate; Bonferroni correction was used in view of the multiple groups. A P < 0.05 was considered significant.
Results: The particles of methylprednisolone and triamcinolone were opaque and amorphous, similar to the findings of Tiso (6). Dexamethasone was pure liquid under the microscope and no particles were noted. The differences in the number of particles 0-20 microns in size and the number of particles >20 between the undiluted steroids were significant (P <0.05). Methylprednisolone, 80 mg/mL, had a greater percentage of 50-100 microns compared to triamcinolone (17% versus 1%). Dilution of the steroids decreased the number of particles. Dilution of methylprednisolone 40 mg/mL and triamcinolone did not alter the proportion of the different particle sizes. Dilution of methylprednisolne 80 mg/mL decreased the percentage of particles in the 50-100 microns range from 17% in the undiluted sample to 9%, 6%, and 5% in the 1:1, 1:2, and 1:3 dilutions respectively.
Discussion: Methylprednisolone, 80 mg/mL concentration, has a greater percentage of large particles compared to triamcinolone. Dilution of methylprednisolone is recommended when the steroid is used for TF ESI. Based on particle size and pending the results with betamethasone, triamcinolone and dexamethasone maybe better steroids for TF ESIs.
References:1. Baker R, et al. Pain 2003;103:211-5.2. Brouwers PJAM, et al. Pain 2001;91:397-9. 3. Huntoon MC, Martin DP. RAPM. 2004;29:494-5. 4. Rathmell JP, et al. Anesthesiology 2004;100:1959-1600. 5. Rathmell JP, Benzon HT. RAPM 2004;29:397-9. 6. Tiso RL, et al. Spine J. 2004;4:468-474.
ATTACHED FILES
Reg Anesth Pain Med 2005; 30(3):A5