Systemic Absorption After Cervical Epidural Steroid Injection
Direct Answer
The provided evidence does not contain specific pharmacokinetic data quantifying systemic absorption rates after cervical epidural steroid injections. However, systemic absorption is clinically significant enough to cause measurable endocrine effects and requires monitoring for hyperglycemia and hypertension in susceptible patients, indicating substantial bioavailability from the epidural space.
Clinical Evidence of Systemic Effects
Documented Systemic Complications
- Cervical ESI carries risks that reflect systemic steroid absorption, including the need to monitor for hyperglycemia and hypertension in susceptible patients 1
- Patients with insulin-dependent or poorly controlled diabetes, labile hypertension, glaucoma, tuberculosis, peptic ulcer disease, and prior psychiatric reactions to corticosteroids may experience systemic complications from epidural injections 1
- Reported complications include not only local effects (dural puncture, insertion-site infections, cauda equina syndrome, sensorimotor deficits) but also systemic retinal complications, suggesting meaningful systemic circulation 2
Dose-Related Considerations
- Current practice shows considerable variability in corticosteroid dosing for cervical ESI, with most physicians (56%) using 10 mg dexamethasone for single cervical injections, though 17% use doses greater than 10 mg and 6% use 20 mg per injection level 3
- For particulate steroids in cervical interlaminar ESI, 55.4% of physicians use 80 mg, with 17% using doses greater than 80 mg 3
- The fact that lower doses (40 mg vs 80 mg methylprednisolone) show comparable efficacy in lumbar ESI suggests that systemic absorption may contribute significantly to therapeutic effect, as local concentrations would differ substantially 4
Important Clinical Caveats
Safety Concerns
- Approximately 10% of physicians continue to use particulate steroids for cervical transforaminal ESI despite guideline recommendations against this practice due to embolic infarct risk 3
- The risk-benefit profile for cervical ESI is less favorable than lumbar ESI, with moderate evidence of benefit but risk of major complications 5
Monitoring Requirements
- Patients receiving cervical ESI require monitoring for systemic corticosteroid effects, particularly insomnia, hyperglycemia, and hypertension 1
- The need for such monitoring confirms that epidurally administered steroids achieve systemic circulation at clinically relevant concentrations
Frequency Limitations
- Most physicians (40%) allow four ESIs at a given spinal segmental level per year, with only 6% allowing more than six annually and 1% allowing more than 10, reflecting concerns about cumulative systemic steroid exposure 3
Key Takeaway
While precise pharmacokinetic data on systemic absorption percentages are not available in the provided evidence, the clinical requirement to monitor for systemic corticosteroid effects (hyperglycemia, hypertension, insomnia) and contraindications in patients with systemic steroid-sensitive conditions clearly demonstrate that cervical ESI results in clinically significant systemic absorption 1.