Spinal Shock and Spinal Injury

Anesthesia Implications

Anesthesia Implications

This condition should NOT be confused with neurogenic shock. Spinal shock describes arreflexia and/or parathesia below the level of injury. This condition is NOT a true form of shock. Since spinal injuries result in this condition, the anesthetic implications will cover both spinal shock and spinal injury in general.

Hemodynamic instability – Liberal crystalloid and blood administration should be used to correct hemodynamic drops – especially in cervical and/or thoracic injuries where sympathectomy causes widespread vasodilation. Standard drugs such as phenylephrine and ephedrine are also acceptable if not contraindicated.

Spinal clearance – always get a spinal clearance. Even if the patient is cleared, take precautions to limit the possibilities of injury while moving the patient or manipulating the airway.

Fiberoptic intubation – if there’s any question of cervical instability, maintain the head and neck in a neutral position at all times and utilize fiberoptic intubation to secure the airway.

Cervical collars/braces – these do not always provide optimal stabilization. DO NOT assume the patients C-spine is stable. See “additional notes” on collars/braces.

Tracheobronchial suctioning – associated with bradycardia and cardiac arrest! This should only be done after optimal oxygenation.

Avoid nitrous oxide – In the event that there is diffuse trauma along with the spinal injury, air entrainment in closed spaces could expand/migrate with the use of nitrous.

Monitor and supplement SaO2 EARLY – muscle weakness, sympathectomy, etc. all contribute to arterial hypoxemia, which is very common after spinal cord injury. Cervical injury (especially C3-C5) – associated with hypoxemia due to disruption of diaphragm innervation. Hypoxemia is an early sign of cervical injury.

Rocurronium/Vecuronium – these are the nondepolarizing neuromuscular blockers (NDNMB) of choice. As a general rule, RSI with Rocurronium is the most common approach to avoid the potential for hyperkalemia associated with Succinylcholine. Succinylcholine may be used for the first 24 hours, but should be avoided thereafter.

MEP monitoring – Ensure that the surgical case does not require MEP monitoring during the case before administering NDNMBs.

Post-operative ventilation – These patients may require prolonged mechanical ventilation depending on the spinal levels affected and severity of the injury.

Maintain cervical neutrality – During transport, always use the C-collar or brace.

Smooth transitions – Ensure the patient is deep enough before intubation. If not contraindicated, deep extubation is sometimes preferred to prevent bucking/coughing. Coughing and/or bucking in these transitions may cause disruption of the surgical site and/or damage to the spine.

Tight temperature control – poikilothermia (the inability to regulate one’s body temperature) is common in spinal cord injuries, so be ready to monitor and maintain normothermia.

Pathophysiology

Not considered a true form of shock

Characterized by flaccid areflexia and/or parathesia BELOW the level of the injury WITHOUT hemodynamic changes.

The major cause of morbidity/mortality in these patients is a combination of alveolar hypoventilation and inability to clear secretions. Be cognizant of atelectasis and perform recruitment maneuvers where possible.

The patient should be able to generate a tidal volume > 10-15 cc/kg and/or a negative inspiratory force of 20 mmHg.

Additional Notes:

Cervical Collar Considerations:
DO NOT remove the collar or brace if the patient arrives with one.
Soft collars have little effect on limiting mobility – so take extra precaution to stabalize the spinal cord during movement of any kind
Hard collars only limit flexion and extension by 25%.
Halo-thoracic braces are the most effective in preventing cervical spine movement.

Classification of this is done using the International Standards for Neurologic Classification of Spinal Cord Injury (ISNCSCI). This tests 28 dermatomes:
Complete injury (classification A) would be total sensory and motor function loss below the level of injury.
Incomplete injury (classification B-D) would be some sensory or motor function maintained below the level of injury.
Normal function (classification E) is injury without the loss of motor or sensory function below the level of injury.

References

Nagelhout. Nurse anesthesia. 5th edition. 2014.
Hines. Stoelting’s anesthesia and co-existing disease. 7th edition. 2018.
Nagelhout. Nurse anesthesia. 5th edition. 2014.
Farag. Airway management for cervical spine surgery. Best Practice & Research: Clinical Anesthesiology. 2016.