Chapter 60: High Spinal

INTRODUCTION

The definition of a high neuraxial block (High Spinal) is the presence of motor blockade above the intended level and which may require tracheal intubation for airway protection (Chapter 31, “Quality Indicators”).¹ High neuraxial block was the leading cause of anesthesia-related maternal death,² and the leading cause of legal claims for maternal death or permanent brain injury filed between 1990 and 2003.³ The incidence of high neuraxial block in obstetric anesthesia is 1:4336 in a complication repository of 257,000 anesthetics, the highest incidence in all serious anesthesia-related complications.¹

These facts highlight the significance of avoidance, recognition, and prompt treatment of this devastating complication. High spinal or total spinal can be managed effectively to ensure patient safety if the anesthesiologist remains vigilant and responds quickly.

CAUSES OF HIGH SPINAL

• Wrong dose in wrong space: Unrecognized intrathecal catheter—immediate onset.

• Subdural catheter—delayed or immediate onset.

• Spinal after failed epidural anesthesia for cesarean delivery—immediate onset.

• Right dose in right space: After an unintentional dural puncture, the epidural catheter was inserted in a different space. During cesarean delivery, epidural local anesthetics enters subarachnoid space through the dural defect from concentration and pressure gradients—delayed onset.

• Wrong dose in right space: Excessive dose of local anesthetics in the epidural space, often in the situation of emergent cesarean delivery.

SYMPTOMS AND SIGNS—VARY AND PROGRESSIVE IN PRESENTATION

• Agitation to sudden loss of consciousness, coma, or seizures

• Muscle weakness, inability to speak to difficult of breathing to respiratory arrest

• Mild hypotension to cardiovascular collapse

• Bradycardia to cardiac arrest

• Paralysis and dysphasia

• Subdural block—may involve the cranial nerves; apnea and Horner’s syndrome can occur

Of note, the physiologic changes in pregnancy lead to significant vasodilation; thus, the hypotension could be mild or absent. The onset of total spinal in the setting of an existing sympathectomy (e.g., after a labor epidural has been in place) may not cause further blood pressure derangement. Usually, inability to speak, agitation, mental status change, and arm/hand weakness are hallmarks of high neuraxial block.

PREVENTION AND TREATMENT (BOX 60-1)

• Continuous monitoring during labor and cesarean delivery.

• Maintain frequent verbal communication with the mother at all times.

• During labor epidural analgesia, the late onset of hypotension and significant muscle weakness in lower extremities must rule out the possibility of intrathecal catheter (Chapter 59, “Intrathecal Catheter”).

• Administration of test dose and careful assessment of the patient’s response.

• Aspiration of epidural catheter before every bolus.

• Incremental dosing of epidural catheter (5 mL each time)—every dose is a test dose.