• A total spinal can result from inadvertent introduction of local anesthetics into the intracranial subarachnoid space. Typically results from unintentional dural puncture, subdural spread, or catheter migration with epidural placement.
• Early signs and symptoms may include anxiety, numbness/weakness of the arms and hands, and dyspnea. As the local anesthetic reaches the brainstem, apnea, hypotension, bradycardia, and loss of consciousness may occur rapidly
• Spread of local anesthetic within the intrathecal space is affected by:
  • Dose
  • Patient position relative to baricity
  • Patient characteristics
  • Spinal/epidural technique
• The potential for a total spinal as well as systemic local anesthetic toxicity make it mandatory that equipment to ventilate, intubate, and resuscitate should be immediately available whenever a neuraxial or regional block is performed.

• Unintentional dural puncture
• Epidural catheter migration
• Surbarachnoid catheter placement
• Subdural spread of local anesthetic causing high block
• Combined spinal epidural (CSE)
• Large volume injection into the epidural space (compresses spinal canal, promoting cephalad spread of intrathecal drugs)
• Injection of local anesthetic at a high thoracic level
• High doses of local anesthetic in spinal block
• Retrobulbar block
• Peripheral nerve blocks
  • Interscalene block
  • Lumbar plexus block
  • Intercostal nerve block (injection via dural cuff extending along nerve root)
  • Blocks performed under general anesthesia
• Pregnancy
• Chronic pain procedures
  • Cervical spine injection

• Local anesthetics block fast sodium channels and neurotransmission when in contact with the spinal cord. Perioperative analgesia and anesthesia can be achieved through blockade of sensory and motor conduction at specific dermatomes targeted to the level of surgical incision.
• However, if cephalad spread of local anesthetic within the intrathecal space occurs, undesired effects, including a total spinal may result. A total spinal is when local anesthetic medications are introduced into the intracranial subarachnoid space, resulting in the sudden onset of apnea, bradycardia, hypotension, and unconsciousness.
• Pathophysiology and clinical manifestations depend on the spinal level that the local anesthetic reaches, and may range from a high spinal to a total spinal.
  • Thoracic. Respiratory difficulty results from the loss of chest wall sensation by paralysis of the intercostal muscles. Patients with a high spinal often describe their breathing as feeling abnormal; however, can demonstrate a good inspiration and can cough and speak normally.
  • Cervical. As the block rises higher, the diaphragmatic nerves (C3, 4, 5) are blocked and respiratory failure develops rapidly.
  • Brainstem. If intrathecal local anesthetic reaches this level, a block of sensory and motor nerves below the neck occurs. Additionally, dilated, nonreactive pupils result from a loss of parasympathetic efferent activity via the Edinger–Westphal nucleus. Hypoperfusion of the respiratory centers results in respiratory arrest.
  • Brain. Loss of consciousness results from diffusion of local anesthetic into the fourth ventricle. Flaccid jaw muscles result from blockade of the motor branch of trigeminal nerve in the rostral subarachnoid cisterns.
• Cardiovascular effects
  • Vasodilation. Venous and arterial vessel dilation result in reduced preload/stroke volume (venous return) and afterload (systemic vascular resistance).
  • Bradycardia. Results from unopposed parasympathetic tone and blockade of the cardio-accelerator fibers arising from T1 to T4. Heart rate may also decrease as a result of a fall in right atrial filling.
  • Cardiac output is impaired due to a combination of reduced stroke volume and heart rate.
  • Cardiac arrest can result from hypotension and hypoxemia.
• Cephalad spread depends on the local anesthetic dose, patient position and characteristics, as well as technique.
  • Local anesthetic dose is determined by concentration, volume, baricity, and presence of vasoconstrictors.
  • Patient position is relevant in relation to the baricity (hyperbaric solution in Trendelenburg; hypobaric in reverse Trendelenburg).
  • Patient characteristics include height, age, gender, intra-abdominal pressure, and anatomical configuration of the spinal cord.
  • Technique includes type of needle, site of injection, direction of needle bevel, velocity of injection, and use of barbotage.
• Pregnancy. Patients have increased intra-abdominal pressure and a diminished volume of the lumbar spinal canal due to distention of the epidural veins. A high spinal or total spinal may result in aspiration or present with severe fetal heart tone decelerations.
• Blocks may continue to extend for at least 30 minutes after injection.
• Although total spinals are often associated with epidural and spinal blocks, peripheral nerve blocks (e.g., brachial plexus interscalene blocks) have been implicated.

• Local anesthetic infusion. Avoid rapid volume injection into the epidural space, avoid dural puncture, and use lower doses of local anesthetic if dural puncture is suspected.
• Aspiration to rule out CSF. Should be performed prior to catheter insertion or bolusing through the epidural needle. A 3 cc syringe is more likely to detect CSF return compared to a 10 cc or larger syringe. Always check for negative aspiration prior to bolusing of local anesthetic.
• Slow injection. Give local anesthetic in incremental doses (3 mL at a time) while continuously monitoring and assessing the patient for signs and symptoms of high spinal (in addition to assessing for local anesthetic toxicity).
• Pregnant patients. Consider lower doses.
• Check sensory level following boluses. Evaluate by assessing for loss of temperature sensation, pinprick, and inability to detect light touch.
• Failed epidurals converted to spinal anesthetics are not associated with high blocks in one retrospective study of 61 patients. However, extra caution is required in the presence of any fluid in the extradural space (volume and time dependent). Consider a reduction in spinal dose or volume.

• High spinal
• Subdural blockade
• Intravascular injection of local anesthetic
• Cerebrovascular accident

• Of 1,480 claims for surgical or obstetric anesthesia using regional or epidural techniques, high or total spinal block comprised 79 cases (5%).
  • Among the 79 high spinal cases, 16 patients died (20%), 23 had permanent disabling outcomes (29%), and 39 (49%) had temporary or nondisabling injuries, 1 with unknown outcome. Payment was made in 47 (59%) of the high block claims, with median payment of $753,500 (payment range: $15,700–$9,000,000).

• Epidural
• Combined Spinal Epidural
• Spinal

995.22

T88.59XA Other complications of anesthesia, initial encounter

Sharon L. Lin , MD

Jane C. Ahn , MD