ABSTRACT
Identification of elicited muscle twitches while performing infraclavicular block of the brachial plexus is often confusing but is critical for success of the block. An easily defined endpoint when evaluating these motor responses to neurostimulation is essential, as it is necessary to block the appropriate cord or cords. In addition to an extensive review of the motor and sensory neuroanatomy of the upper extremity, we describe an easy method to learn and remember the motor response to stimulation of each of the cords of the brachial plexus. If the arm is positioned in the anatomical position, the 5th digit (pinkie) moves laterally (pronation of the forearm) when the lateral cord is stimulated, posteriorly (extension) when the posterior cord is stimulated, and medially (flexion) when the medial cord is stimulated. The pinkie thus moves "toward" the cord that is stimulated.
Subject(s)
Brachial Plexus/anatomy & histology , Electric Stimulation , Muscle Contraction/physiology , Muscle, Skeletal/innervation , Nerve Block/methods , Arm/innervation , Axilla/innervation , Brachial Plexus/physiology , Fingers/innervation , Forearm/innervation , Hand/innervation , Humans , Median Nerve/anatomy & histology , Median Nerve/physiology , Motor Neurons/physiology , Musculocutaneous Nerve/anatomy & histology , Musculocutaneous Nerve/physiology , Neurons, Afferent/physiology , Radial Nerve/anatomy & histology , Radial Nerve/physiology , Wrist/innervationABSTRACT
We present a patient who required perioperative analgesia with continuous nerve block for shoulder disarticulation, for whom the only approach possible to the brachial plexus was from posterior. A 51-yr-old woman was suffering from intractable upper extremity pain and dysfunction as a result of severe lymphedema after metastatic spread of breast cancer to the axilla. Her pain was poorly controlled despite aggressive treatment with oral, systemic, and intrathecal opiates. She presented for amputation of her arm as a last resort for management of pain. In order to provide optimal postoperative analgesia, continuous peripheral nerve block was selected in consultation with the patient, and due to anatomic disfigurement and tumor invasion, a continuous cervical paravertebral block was placed preoperatively and shoulder disarticulation was performed using a combined regional/general anesthesia technique. The patient had an uneventful recovery without pain for the 6 postoperative days that the catheter was in place and 0.25% bupivacaine was infused at 5 mL/h. Because of anatomic considerations, which precluded the use of all other approaches to the brachial plexus, the posterior cervical paravertebral approach provided an effective means of pain control in this difficult clinical situation.
