Nerve Blocks Steven Lanski, MD Assistant Professor Pediatrics and Emergency Medicine Emory University

What is Pain?

International Assoc for the Study of Pain: “an unpleasant sensory and emotional experience connected with actual or potential tissue damage…” afferent impulses from averse stimuli processing of that information

Factors Involved Thickness Myelination Perception

Components of the Pain System: Sensation Afferent fibers  “A” delta fibers : mechanoceptors (pressure) small, lightly myelinated …”first” pain rapid, sharp, localized  “C” fibers: polymodal (heat,chemical) unmyelinated (slower)…”second” pain delayed, prolonged, dull, poorly localized

Mechanism of Action Decreases sodium influx across neuronal membranes Decreases polarization amplitude No action potential No impulse

Duration of action Dependant upon protein binding and blood supply.

Adverse Reactions Cardiovascular - hypotension, bradycardia CNS - excitatory - seizures Allergic - preservative - methylparaben esters - tetracaine, benzocaine, procaine, cocaine amides - lidocaine, bupivacaine, diphenhydramine (1%) Anxiety

Locations Facial Supraorbital and trochlear infraorbital mental ear dental Extremity digital radial median ulnar sural tibial

Supraorbital/Supratrochlear Blocks Helpful for multiple lacerations of forehead and anterior scalp

Supraorbital/Supratrochlear Blocks Landmark - superior orbital rim

Infraorbital Block Anesthesia to lower eyelid, lateral inferior nose and lower lip

Infraorbital Block Landmarks - canine, infraorbital foramen

Mental Nerve Block Anesthesia to lower lip and partial chin

Mental Nerve Block Landmark - 2nd bicuspid

Auricular Block

Dental Blocks Local Inferior Alveolar - anesthesia to the mandible, teeth and chin

Inferior Alveolar Block Landmarks - ramus of the mandible and coronoid notch

Digital Blocks Dorsal and palmar digital nerves Toes (except 1st) single needle insertion

Digital Blocks Landmarks - bone and web space

Thumb Block

Median Nerve Block Anesthesia to palm (radial half), 1st-3rd digits Landmark - proximal flexor crease, radial artery, flexor carpi radialis and palmaris longus tendons.

Ulnar Nerve Block Anesthesia to dorsal and palmar aspect of hand (ulnar half), ulnar half of 4th digit and 5th digit Landmarks - flexor carpi ulnaris and ulnar artery - dorso-ulnar aspect wrist (2nd branch)

Radial Nerve Block Anesthesia to dorsal surface of 1st-3rd digits and radial portion of hand Landmark – dorso-radial aspect of wrist

Sural Nerve Block Anesthesia to heel and lateral half of foot Landmarks - lateral malleolus, Achilles tendon

Posterior Tibial Block Anesthesia to the medial aspect of the foot Landmark - posterior tibial artery, Achilles tendon and medial malleolus

Penile Block Landmarks - base of penis and Buck’s fascia

Conclusion Choice of agents based on duration required Beneficial for multiple or extensive injuries in which conscious sedation will not be performed More comfortable than local infiltration in some sites