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Neurogenic Shock

Incidence of Neurogenic Shock during Acute SCI

Discussion

Neurogenic shock is thought to be largely a consequence of a sudden reduction of sympathetic activity and output peripherally after SCI, in particular higher level SCIs. In order to determine how often this complication occurs in recently injured individuals, eight studies were found which investigated the incidence of neurogenic shock during acute SCI. Of these studies, most used the term “neurogenic shock” when defining outcome measures, while others explicitly stated neurogenic shock as being determined by the presence of hypotension and bradycardia or by the presence of hypotension only.

A total of seven observational studies were conducted, examining the occurrence of neurogenic shock upon hospital admission. Zipnick et al. (1993) retrospectively reviewed patients who were admitted to an emergency department, and noted acute neurogenic shock as having an incidence rate of 7% at the time of arrival. Mallek et al. (2012) reviewed patients admitted to a trauma center beginning from their time of admission, and observed a neurogenic shock incidence rate of 8.8%; 24% of these patients had cervical SCI whereas 5.5% had thoracic SCI. Guly et al. (2008) reviewed patients at first presentation to the emergency department. The incidence of neurogenic shock was subdivided by level of injury; 19.3%, 7%, and 3% of cervical, thoracic, and lumbar SCI patients developed neurogenic shock, respectively. Nakao et al. (2012) reviewed cervical SCI patients at 1 month after sustaining injury to investigate the incidence of hypotension. Within this population, 45.3% of patients were hypotensive. In a study by Bilello et al. (2003), patients who had sustained a high cervical (C1-C5) injury were reviewed and compared to patients who had sustained a lower cervical (C6-C7) injury. Patients were studied during the initial 24 hours of their intensive care unit stay (ICU). Neurogenic shock developed in 31% and 24% of high injury and low injury patients, respectively, although there was no significant difference in frequency of occurrence between these groups (p=0.56). Grossman et al. (2012) sought to determine the incidence of various acute complications that arise following SCI. Acutely injured patients were included in the study beginning from the time of hospital admission. Cardiac complications accounted for 21% of the most frequent severe complications, of which 45% was severe bradycardia. Ravensbergen et al. (2014) evaluated SCI patients where data was collected on 5 occasions: at the start of and 3 months into inpatient rehabilitation, at rehabilitation discharge, and at 1 and 5 years after discharge. At the start of inpatient rehabilitation, participants were on average 100 days post injury, and the incidence of hypotension and bradycardia were recorded individually. Within this population, 33% of patients had hypotension and 4.5% of patients had bradycardia at the start of rehabilitation. The authors noted that there was no significant change in the prevalence of these acute complications over time.

Finally, Tuli et al. (2007) conducted a post-hoc analysis of a multicenter RCT in part to assess the incidence of neurogenic shock among cervical SCI patients. Patients were acutely injured and were assessed beginning at their time of arrival at the emergency department. Neurogenic shock developed in 13% of patients, and was higher among AIS A (17%) and B (18%) patients compared to AIS C/D (7%) patients.

Conclusion      

The incidence of neurogenic shock ranges from 7% to 45% in acute SCI patients (based on one RCT and four observational studies; Tuli et al. 2007; Mallek et al. 2012; Nakao et al. 2012; Bilello et al. 2003; Zipnick et al. 1993).

The incidence of neurogenic shock is higher in patients with AIS A and B injuries compared to AIS C and D injuries (based on one RCT; Tuli et al. 2007).

The incidence of neurogenic shock ranges from 19% to 29% in patients with a cervical SCI and from 5.5% to 7% in patients with a thoracic SCI (based on three observational studies; Mallek et al. 2012; Guly et al. 2008; Bilello et al. 2003). 

  • The incidence of neurogenic shock during the acute phase post SCI ranges from 7% to 45%; Patients with cervical injuries have a higher incidence rate than patients with lower-level injuries.