Guidelines for Response to Motor Block During Epidural Analgesia NEW

December 2007

Overview
Local anesthetics administered via the epidural space can produce motor block as an expected drug effect. During epidural analgesia it is not desirable to have motor block which limits ambulation. When motor block is identified, the differentiation between "normal" drug effect vs. other potential causes (including cord compression from an epidural abscess or hematoma, intrathecal migration of the catheter, inadvertent administration of another agent via the epidural, nerve injury etc.) should be considered.  

Prompt evaluation and vigilant follow-up for resolution are important. Treatment within 8 hours of symptoms resulting from cord compression by hematoma or abscess is generally associated with the best outcome.

Patient Evaluation

The patient should be evaluated and treatment decisions made in the context of multiple factors including:

  • The location and degree of motor block and of sensory changes  

  • The level of the catheter

  • The concentration and volume of local anesthetic infusing

  •  Was a bolus dose of local anesthetic administered in the last 1-2 hours, and/or was there a change in the epidural infusion?

  • Was the onset sudden or gradual?

  • Can CSF be aspirated from the catheter?

  • Are there any other symptoms, such as back pain, fever, headache, urinary incontinence or retention, bowel incontinence?

Treatment Considerations

  •  Motor block with no sensory block is not a typical profile of epidural bupivacaine. Look for other causes of the motor block.

  • Communicate with the surgeon or primary team regarding any concerns.

  • Residents carrying the APMS beeper must call the covering attending and discuss treatment plans with any calls regarding motor deficit.

If the motor block is significant and/or represents a sudden change:

  •  Turn the infusion off (instruct the nurse to save the solution container-do not discard).  

  •  Enter nursing orders for hourly assessment of leg strength and numbness, and to call APMS for any deterioration or if leg strength and sensation have not returned to baseline in 3 hours

  •  Aspirate for CSF

          If aspiration is positive for CSF - Turn the infusion off until the patient is able to bend the knees and lift legs off the bed, then replace the catheter, or change the infusion to an appropriate dose for an intrathecal infusion (generally start with bupivacaine 1mg/hr). Replacing the epidural is recommended unless a difficult insertion is anticipated.

          If aspiration is negative for CSF - Resume the infusion at a lower rate or lower concentration when the patient is able to bend the knees and lift legs off the bed.  Generally if the catheter is located in the lumbar region, a change to a lower concentration bupivacaine (i.e., 0.0625%) should be considered.

If the motor block has not resolved in 4 hours, obtain a stat MRI to evaluate for intraspinal process.  

  • During regular weekday work hours, call the MRI Scanner Console at ext. 4028.

  •  After hours, or on weekends, call the Radiology Resident on-call beeper 767-6694.

Request a stat neurosurgical consult if the MRI indicates abscess or hematoma. Send the infusion solution container to the lab for content analysis. 

When there is some leg weakness, but the patient is able to bend the knees, consider turning the epidural infusion rate down by 20-30% and re-evaluate in 2 hours. If the motor block persists, turn the infusion off until the block is resolved and follow the instructions listed in # 4 above.