Traumatic spinal cord injury

Introduction
Traumatic spinal cord injury (TSCI)

Guidelines
2013 AANS/CNS Updated Guidelines for the Management of Acute Cervical Spine and Spinal Cord Injury

2019 AANS/CNS Guidelines for the Evaluation and Treatment of Patients with Thoracolumbar Spine Trauma

Spinal cord contusion
Intramedullary spinal cord hematoma is most commonly due to traumatic cord contusion. Spinal cord gray matter is more susceptible. Gray matter may show hypointensity in the anterior horns with DWI from susceptibility effects, in contrast to surrounding DWI hyperintensity from cytotoxic edema. This pattern has been referred to as looking similar to a mask on axial images.

Blood pressure management
Avoid hypotension. Although there is very limited evidence and no prospective controlled studies, data suggests that hypotension should be avoided at all costs. First priority is adequate fluid resuscitation

Strongly consider maintaining MAP ≥85 mmHg for at least 3 days (and possibly 5-7 days), which may be of benefit in improving functional outcome after spinal cord injury. Alternatively, one can consider placing a lumbar drain and monitoring spinal cord perfusion pressure (SCPP) which some studies have suggested correlates more strongly with outcome than MAP. If this is done, it is reasonable to target SCPP of 60-65 mmHg. Favor norepinephrine and possibly phenylephrine (especially in lower thoracic injury), while avoiding dopamine which has been associated with higher complications.

Original data and guidelines
Laboratory evidence has suggested that hypotension contributes to secondary injury in acute TSCI by reduced cord perfusion, and hypotension in animal models leads to worsened neurological outcomes. In 1976 Zäch et al. used volume expansion with dextran 40 to maintain SBP for 7 days after injury and reported improved neurological outcomes. In 1984 Tator et al. published on 144 patients also given volume expansion for maintain perfusion and noted lower mortality, reduced morbidity, and a shorter length of stay compared with a cohort of prior years at the same hospital who did not receive such therapy. In 1991 Wolf et al. specifically targeted MAP >85 mmHg for 5 days with good outcomes in 52 patients, and then Levi et al. published a similar series of 50 patients treated to goal MAP >90 mmHg who had good outcomes. In 1997 Vale et al. reported significant improvement in 77 patients given fluids and vasopressors to target MAP >85 mmHg for 7 days.

Their collective experience led to recommendations to maintain MAP >85 or >90 mmHg after TSCI. Importantly, this elevated MAP goal targeted in these early prospective studies was essentially arbitrary, and the initial recommendations were based on zero controlled studies on this topic. Since that time there has been one study with a retrospective control in 2017 by Dakson et al. in 94 patients which showed improved outcome in those who had MAP >85 mmHg for 5 days compared with those who did not. However, as a retrospective study, this result could be due to confounders.
 * 2002 AANS/CNS Guidelines for Management of Acute Cervical Spinal Injuries:
 * There is insufficient evidence to support treatment standards or guidelines. "Hypotension (systolic blood pressure <90 mmHg) should be avoided if possible or corrected as soon as possible after spinal cord injury. Maintenance of mean arterial blood pressure at 85 to 90 mm Hg for the first 7 days after acute spinal cord injury to improve spinal cord perfusion is recommended"."
 * 2013 AANS/CNS Updated Guidelines for the Management of Acute Cervical Spine and Spinal Cord Injury:
 * Level III: "Management of patients with an acute cervical spinal cord injury in an intensive care unit or similar monitored setting is recommended."
 * Level III: "Use of cardiac, hemodynamic, and respiratory monitoring devices to detect cardiovascular dysfunction and respiratory insufficiency in patients following acute spinal cord injury is recommended."
 * Level III: "Correction of hypotension in spinal cord injury (systolic blood pressure < 90 mm Hg) when possible and as soon as possible is recommended."
 * Level III: "Maintenance of mean arterial blood pressure between 85 and 90 mm Hg for the first 7 days following an acute spinal cord injury is recommended"
 * 2019 AANS/CNS Guidelines for the Evaluation and Treatment of Patients with Thoracolumbar Spine Trauma:
 * There is insufficient evidence to make recommendations about blood pressure after thoracolumbar spinal cord injury, but "in light of published data from pooled (cervical and thoracolumbar) spinal cord injury patient populations, clinicians may choose to maintain arterial blood pressures >85 mmHg in an attempt to improve neurological outcomes."

Data on BP targets

 * MAP >85
 * Initial data from the aforementioned studies had looked arbitrarily at this goal.   In 2015, Hawryluk et al. retrospectively studied MAP correlations with outcome in 74 patients and noted that benefit in outcome appeared to occur at MAP values of 70-75 mmHg but that MAP >85 mmHg better discriminated those who good recovery from minimal or no recovery.  In the only study with a control, Dakson et al. retrospectively analyzed 94 patients and stratified them into those with MAP <85 mmHg for 2 consecutive hours vs those who did not (all had goal of >85 mmHg for 5 days).  They found that the lower MAP group had worsened outcomes, independent of severity of injury or early surgery.
 * We are awaiting the results of two trials randomizing patients to MAP >65 mmHg or >86 mmHg. The Mean Arterial Blood Pressure Treatment for Acute Spinal Cord Injury (MAPS, NCT02232165) study ended recruitment in 2019 but results are not yet available.  Also,  as the Randomized Trial of Early Hemodynamic Management of Patients Following Acute Spinal Cord Injury (TEMPLE, NCT02878850) is ongoing, and aims to recruit 152 participants by 2022.
 * MAP >70
 * In 2010, Cohn et al. did a retrospective study of 17 patients and found that the percent of time with MAP ≤70 correlated with worsened motor gains, but that there was no significant correlation of outcomes with goal MAPs ≥75 mmHg. This suggested that the MAP goal of >85 mmHg in guidelines may not be appropriate.
 * In 2017, Squair et al. prospectively monitored patients and found an optimal MAP cutoff of >70 mmHg for improved neurological outcome. However, this did not correlate with outcome as strongly as spinal cord perfusion pressure (see below).
 * Spinal cord perfusion pressure (SCPP) of 60-65 mmHg
 * In 2017, Saadoun et al. published a study in which they placed subdural intraspinal pressure monitors at the injury site intraoperatively during posterior fixation in 45 patients with TSCI. Mean intraspinal pressure of <10 mmHg or SCPP of >90 mmHg were associated with the best motor recovery at 9-12 months post-injury, while there was no correlation of MAP and recovery. However, placement of these monitors required surgery.
 * Also in 2017, Squair et al. published a study of 92 patients with TSCI who had lumbar drains placed and MAP and CSF pressures were monitored for 120 hours. A SCPP of >50 mmHg correlated most highly with improved outcomes.  These data were re-analyzed in 2019, and suggested an optimal SCPP range of 60-65 mmHg, which correlated well with improved outcomes, while at higher pressures there were diminishing returns and it was difficulty to maintain them at these pressures.

Duration of elevated MAP
Initial goals of maintaining elevated MAP for 7 days were fairly arbitrary, and based on studies suggesting spinal cord edema peaks at 3-5 days post-injury. Most of the potential benefit in elevated MAP appears to occur in the first 3 days, but there may be some benefit thereafter. Several studies have used only 5 days and there has not been any clear difference in outcome, but no direct comparisons have been made.

Complications of maintaining elevated MAP
In a retrospective study of 131 patients given pressors for goal MAP >85 mmHg (60% dopamine, 34% phenylephrine, 6% norepinephrine or epinephrine), 70% of patients had a complication, including: Similar results were found in a 2015 study which showed 76% cardiogenic complication rates of vasopressors in TSCI patients.
 * Tachycardia (40%)
 * Bradycardia (24%)
 * Atrial fibrillation (12%)
 * Ventricular tachycardia (11%)
 * Elevated troponin and/or ST changes (6%)
 * Acidosis (3%)
 * Atrial flutter (~1%).
 * Skin necrosis (~1%).

Vasopressor agent
There is limited data available to suggest a particular vasopressor agent. In cervical and upper thoracic spinal cord injury (above T6), acute loss of sympathetic innervation can lead to sinus bradycardia (from absence of sympathetics to the heart) and hypotension (from absence of sympathetic vasoconstriction of vasculature). In lower thoracic injury, the heart is unaffected but hypotension can still result from absent sympathetic stimulation to the vasculature. Possible agents for treatment of hypotension include:
 * Norepinephrine: probably the best agent to use as it will treat both of these problems and has the best evidence in shock overall.
 * Phenlyephrine may be more immediately available and can be started acutely for hypotension if needed -- it is unlikely to severely exacerbate sinus bradycardia if only being used to raise a patient's BP back to normotension. May also be more appropriate in lower thoracic spinal cord injury when bradycardia won't be an issue.
 * Dopamine: should probably be avoided as data suggests increased complications. One retrospective study of 131 patients showed that, compared with phenylephrine, dopamine was associated with a higher risk of tachycardia (OR 2.93, 95% CI 1.51-5.69), a higher risk of serious EKG changes or troponin elevations (OR 3.74, 95% CI 1.01-13.84),and a higher risk of atrial fibrillation (OR 8.071, 95% CI 1.80-36.3). Another small retrospective study showed similarly high complication rates with dopamine including 10% having ventricular tachycardia, 16% having atrial fibrillation, and 6% having elevated troponin levels.
 * Epinephrine: also reasonable but may cause more arrhythmias

Complications
Any adverse event is associated with a decreased likelihood of neurological improvement (aOR 0.55, 95% CI 0.32-0.94), and an increased likehood of requiring assisted breathing (aOR 6.55, 95% CI 1.17-36.67), supported ambulation (aOR 7.38, 95% CI 4.35-13.06), urinary catheterization (aOR 9.63, 95% CI 5.19-17.87), and irregular bowel motion (aOR 7.86, 95$ CI 4.31-14.32), after adjustment for baseline ASIA scale, age, and injury level.

Pulmonary
These are the most common after SCI, and made up 25% of all complications in one multicenter prospective study. Pneumonia was the most common (see ID section below), followed by respiratory failure, pleural effusion, and various other complications.

Infectious diseases
These made up 19% of complications in one multicenter prospective study, predominantly pneumonia and then UTI, followed by sepsis and other infections.

Hematological
These made up 18% of complications in one multicenter prospective study, predominantly anemia, with some cases of DVT, coagulopathy, and thrombocytopenia.

Cardiac
These made up 15% of complications in one multicenter prospective study, predominantly bradycardia followed by shock.

GI/GU
These made up 10% of all complications in one multicenter prospective study, with ileus and GI hemorrhage most common, followed by acute renal failure.

Skin
These made up 8% of all complications in one multicenter prospective study, mostly sacral ulcers and occasionally surgical wound problems.

Neuropsychiatric
These made up 7% of all complications in one multicenter prospective study, most commonly depression with occasional cases of psychosis or other cognitive decline.

Imaging parameters
A smaller lesion size and a larger width of midsagittal tissue bridges at one-month post SCI on MRI predicted better 1-year outcomes in a small study of mixed TSCI and spinal cord infarction.