Spinal Shock

Original Editor - Cindy John-Chu

Top Contributors - Cindy John-Chu, Kim Jackson and Vidya Acharya  

Overview

Also known as spinal shock syndrome, spinal shock is the loss of muscle tone and spinal reflexes below the level of a severe spinal cord lesion[1]. This "shock" does not imply a state of circulatory collapse but of surpressed spinal reflexes below the level of cord injury[2]. It takes between days and months for spinal shock to completely resolve and when it does, the flaccidity that was once seen gradually becomes spasticity[3]. It usually is consequent to severe spinal cord injury (SCI) that is either traumatic or ischaemic, with traumatic spinal shock occuring more in young people and mostly among males than females[4]. Spinal shock is characterized by a temporary rise in blood pressure that is proceeded by hypotension, flaccid paralysis, urinary retention and faecal incontinence[4]. If reversal of symptoms does not occur within 24hrs, it may call for protracted recovery time and lengthened stay in rehabilitation[4].

Differential Diagnoses of Spinal Shock

These include:

Complications of Spinal Shock

Differences between Neurogenic Shock and Spinal Shock

Neurogenic shock:

  • Also known as vasogenic shock
  • Defined as systolic blood pressure less than 100 mm Hg with a heart rate less than 80 bpm[5]
  • Consequent to SCI with associated autonomic dysregulation[5]
  • Common with cord injuries above T6 level. In other words, it is associated with cervical and high thoracic spine injury.
  • Occurs at anytime from the onset of injury
  • Frequently follows a traumatic SCI[5], but may also occur in non-traumatic cord lesions[6]
  • Characterized by:
    • Systemic hypotension and bradycardia
    • Respiratory insufficiency and pulmonary dysfunction
    • Temperature dysregulation vis-à-vis hypothermia; flushed, warm skin
  • Lasts between 1 to 6 weeks post the initial injury
  • Managed by administering fluids and vasopressors with appropriate temperature monitoring[7]

Spinal shock:

  • Defined as a state of transient physiologic (rather than anatomic) reflex depression of cord function below the level of injury, with associated loss of sensorimotor functions[8]
  • Is a reversible reduction or loss in sensory and motor function after an acute SCI
  • Rarely occurs in spinal cord lesions of gradual onset
  • Involves reflex depression of cord function below the level of injury[9]
  • When reflexes return, they follow a pattern where superficial ones show up before deep tendon reflexes[8].
  • Characterized by:
    • Flaccid paralysis
    • Anaesthesia
    • Areflexia or hyporeflexia[7]
  • Lasts between days to months
  • Most often resolves on its own
[10]

Stages of Spinal Shock

The resolution of spinal shock does not occur abruptly but in phases. Ditunno et al (2004)[11] proposed a four-phase model of the syndrome.

Phase 1

  • Lasts between 0 to 1 day
  • Characterized by loss of descending facilitation
  • Presents as areflexia or hyporeflexia

Phase 2

  • Occurs between 1 to 3 days post injury
  • Shows as denervation supersensitivity
  • Leads to initial re-emergence of reflexes

Phase 3

  • Lasts between 4 days to 1 month
  • Axon-supported synapse growth occurs at this stage
  • Initial hyper-reflexia is elicited here

Phase 4

  • Lasts between 1 to 12 months
  • Soma-supported synapse growth occurs
  • Presents as spasticity

Conclusion

While spinal shock may not be easily prevented, it can be managed and often requires a multidisciplinary team effort to do so. Its understanding and that of its mechanisms will enable the application of interventions that will facilitate recovery.

References

  1. Smith PM, Jeffery ND. Spinal Shock-Comparative Aspects and Clinical Relevance. Journal of Verterinary Int Med 2008; 19(Iss 6)
  2. Singhal V, Aggarwal R. Spinal Shock. In: Prabhakar H. Complications in Neuroanesthesia. Academic Press: Science Direct, 2016. p89-94.
  3. Ko HY. Spinal Shock. In Management and Rehabilitation of Spinal Cord Injuries. Singapore: Springer, 2019. pg123-134.
  4. 4.0 4.1 4.2 4.3 4.4 Ziu E, Mesfin FB. Spinal Shock. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020. p1-11.
  5. 5.0 5.1 5.2 Dave S, Cho JJ. Neurogenic Shock. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020; p1-10.
  6. Flanagan EP, Pittock SJ, Diagnosis and Management of Spinal Cord Emergencies. In: Wijdicks EFM, Kramer AH editors. Handbook of Clinical Neurology. Elsevier, 2017. p319-335.
  7. 7.0 7.1 Volski A, Ackerman DJ, Neurogenic Shock. In: Stawicki SP, Swaroop M editors. The Science and Art of Physiological Restoration. IntechOpen, 2019.
  8. 8.0 8.1 Singhal V, Aggarwal R, Spinal Shock. In: Prabhakar H editor. Complications in Neuroanaesthesia. Academic: Science Direct, 2016. p89-94.
  9. Graells XS, Benato ML, del Santoro PG, et al. Spinal Cord Injury. In: Nasr A, Saavedra TF, Collaço I, Abreu P, Namias N, Marttos. The Trauma Golden Hour. Cham: Springer, 2020. p65-72.
  10. ACLS Certification Association. Neurogenic shock vs. Spinal shock. Available from: https://youtu.be/nPu7RW2JBkw [last accessed 10/1/2021]
  11. Ditunno JF, Little JW, Tessler A, Burns AS. Spinal shock revisited: a four-phase model. Spinal Cord. 2004; 42:383-395.