Is it physiologically possible to experience numbness in the throat after a cervical epidural steroid injection?

Throat Numbness Following Cervical Epidural Steroid Injection: Physiological Mechanisms

Throat numbness following a cervical epidural steroid injection is physiologically possible due to inadvertent spread of local anesthetic to nerve structures that innervate the throat, though this is uncommon and should prompt careful evaluation for proper needle placement and medication distribution.

Anatomical and Physiological Considerations

The anatomical proximity of the cervical epidural space to structures that innervate the throat creates several potential mechanisms for throat numbness:

1. Vagus Nerve Involvement:

   • The vagus nerve (cranial nerve X) provides sensory innervation to the pharynx and larynx
   • Spread of local anesthetic solution from high cervical injections could potentially affect vagal branches

2. Spread of Injectate:

   • Cervical epidural injections typically involve 10-15 mL of solution 1
   • This volume can spread both cephalad (upward) and caudad (downward) from the injection site
   • High cervical injections (C3-C7) may allow spread to areas innervating the throat

3. Vascular Uptake Mechanisms:

   • Inadvertent intravascular injection could distribute anesthetic to areas supplying the throat
   • The vertebral artery and its branches are in close proximity to cervical injection sites 2

Clinical Evidence and Considerations

The FDA drug label for lidocaine (commonly used in epidural injections) specifically notes that persistent paresthesias of the oral tissues have been reported, particularly involving the trigeminal nerve and its branches 3. This supports the possibility of similar effects in throat tissues.

Epidural steroid injections are commonly performed at various cervical levels, with C5-6 and C6-7 being the most common injection sites 4. While throat numbness is not specifically documented as a common side effect, various neurological symptoms have been reported:

• Reported complications include upper extremity weakness (transient) 1
• Inadvertent intravascular injections can cause neurological symptoms 2
• Spread of anesthetic can affect nerve roots beyond the targeted area

Differential Considerations

When a patient reports throat numbness after cervical epidural injection, consider:

1. Timing of symptoms:

   • Immediate onset suggests direct anesthetic effect
   • Delayed onset may indicate other mechanisms or unrelated causes

2. Alternative explanations:

   • Psychosomatic response to procedure
   • Pre-existing but previously unnoticed sensory changes
   • Vasovagal reaction affecting sensation perception 3

3. Concerning signs requiring urgent evaluation:

   • Difficulty breathing or swallowing
   • Voice changes
   • Progressive neurological symptoms

Clinical Implications

While throat numbness is not among the commonly reported side effects in large studies of cervical epidural injections 4, 1, the anatomical and physiological mechanisms make it a plausible occurrence. The safety profile of properly performed cervical epidural injections shows a low rate of serious complications (0.06% in a study of 12,168 procedures) 4, but vigilance for unusual symptoms remains important.

For clinicians performing these injections, best practices include:

• Using fluoroscopic guidance with epidurography to confirm proper needle placement
• Careful aspiration before injection to avoid intravascular administration
• Starting with small test doses before full injection
• Monitoring for unexpected sensory changes in areas beyond the expected distribution

In conclusion, while not commonly reported in the literature, throat numbness following cervical epidural steroid injection has a plausible physiological basis and should prompt careful evaluation of injection technique and medication spread rather than dismissal as impossible.