'SCALD-ED' Block: Superficial Cutaneous Anesthesia in a Lateral Leg Distribution within the Emergency Department - A Case Series

Abstract

Background: In the midst of a nationwide opioid epidemic, focus has been placed on identifying and utilizing safe, effective opioid-free analgesic alternatives. Lower-extremity peripheral nerve blockades are common and often involve both motor and sensory anesthesia, resulting in leg weakness and ambulatory difficulty. The aim of this case report is to describe an ultrasound-guided peripheral nerve block technique (superficial cutaneous anesthesia in a lateral (leg) distribution within the emergency department ['SCALD-ED' block]) that provides motor-sparing, purely sensory anesthesia after a superficial injury to the lateral leg in patients presenting to the emergency department.

Discussion: Two separate patients presenting with lateral leg pain after superficial injury (burn, cellulitis) reported continued breakthrough pain despite a standard analgesic modality of combination acetaminophen and ibuprofen. With the patient placed in prone position for ultrasound-guided access to lower-extremity nerve branches, the lateral sural cutaneous nerve (LSCN) was identified by tracing its pathway from the proximal sciatic nerve to the common peroneal (fibular) nerve to the superficial peroneal (fibular) nerve. Five mL of lidocaine (1%, with epinephrine) was injected along the superficial LSCN route for anesthetic blockade. Temporal assessments of anesthetic effect and pain improvement, and monitoring of motor or ambulatory impairment were conducted at regular intervals to assess the efficacy and feasibility of the blockade. Regional anesthesia along the LSCN sensory distribution was experienced at 7-9 min post blockade. Peak analgesic effect was experienced at 25-29 min. The duration of anesthesia was 120-150 min. A negligible amount of delayed sensory anesthesia was noted along the distal sural nerve distribution. No motor deficit, ambulatory difficulty, or adverse effects were experienced in either patient post blockade.

Conclusion: The LSCN is an identifiable target under ultrasound guidance, susceptible to localized, purely sensory blockade of pain from superficial cutaneous lateral leg injuries.

Keywords: burns; lateral sural cutaneous; leg injury; pain; regional anesthesia; ultrasound-guided.