Study guide
20.2 Acute Spinal Cord Injury, Neurogenic Shock & Autonomic Dysreflexia
ABIM Critical Care Medicine Study Guide Exam
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1 Chapter 1: Exam Orientation: Format, Blueprint & Study Strategy
1.1 ABIM Critical Care Medicine Exam: Format, Blueprint & Study Strategy
2 Chapter 2: Acute Respiratory Failure & ARDS
2.1 ARDS Definition, Pathophysiology & Phenotypes 2.2 Lung-Protective Mechanical Ventilation 2.3 Refractory ARDS: Prone Positioning, Neuromuscular Blockade & VV-ECMO
3 Chapter 3: Obstructive Airways, Pulmonary Vascular & Pleural Emergencies
3.1 Severe Asthma & COPD Exacerbations in the ICU 3.2 Massive & Submassive Pulmonary Embolism 3.3 Pulmonary Hypertension & Right Ventricular Failure in the ICU 3.4 Massive Hemoptysis, Complex Pleural Effusions & Thoracic Drainage
4 Chapter 4: Airway, Parenchymal & Nonthrombotic Pulmonary Emergencies
4.1 Airway Management, Upper-Airway Obstruction & Artificial-Airway Complications 4.2 Diffuse Alveolar Hemorrhage, Interstitial Lung Disease, Pulmonary Vasculitis & Noncardiogenic Edema 4.3 Severe Community-Acquired & Viral Pneumonia 4.4 Nonthrombotic Embolism (Air, Fat, Amniotic Fluid, Tumor, Septic) & Acute Chest Syndrome
5 Chapter 5: Mechanical Ventilation Modes, Dyssynchrony & Liberation
5.1 Mechanical Ventilator Modes & Advanced Breath Delivery 5.2 Patient-Ventilator Dyssynchrony & Waveform Analysis 5.3 Ventilator Liberation, Spontaneous Breathing Trials & Post-Extubation Support
6 Chapter 6: Shock Syndromes & Hemodynamic Principles
6.1 Shock Classification, Cellular Pathophysiology & Biomarkers 6.2 Hemodynamic Monitoring: Arterial Lines, CVP & Pulmonary Artery Catheter 6.3 Dynamic Assessment of Fluid Responsiveness & Resuscitation Targets
7 Chapter 7: Vasoactive Therapies & Mechanical Circulatory Support
7.1 Vasopressors & Inotropes: Pharmacology & Clinical Titration 7.2 Temporary Mechanical Circulatory Support: IABP, Impella & TandemHeart 7.3 Venoarterial ECMO (VA-ECMO) & Differential Hypoxemia 7.4 Post-Cardiac Arrest Care, Targeted Temperature Management & Neuroprognostication
8 Chapter 8: Acute Kidney Injury & Renal Replacement Therapy
8.1 KDIGO AKI Classification, Etiologies & Diagnostic Evaluation 8.2 Continuous Renal Replacement Therapy (CRRT) vs Intermittent Hemodialysis 8.3 Indications & Timing for RRT in Critical Illness: AKIKI & STARRT-AKI
9 Chapter 9: Electrolyte, Acid-Base & Endocrine Emergencies
9.1 Severe Dysnatremias: Hyponatremia, Hypernatremia & Osmotic Demyelination 9.2 Potassium, Calcium, Magnesium & Phosphate Disorders 9.3 Complex & Mixed Acid-Base Disorders: Boston vs Copenhagen vs Stewart 9.4 Endocrine Crises: DKA, HHS, Thyroid Storm, Myxedema Coma & Adrenal Crisis
10 Chapter 10: Glycemic Control, Hyperammonemia, Pituitary & Adrenal Disorders
10.1 ICU Glycemic Control & Severe Hypoglycemia 10.2 Non-Hepatic Hyperammonemia & Metabolic Encephalopathy 10.3 Pituitary Emergencies, Adrenal Excess & Critical Illness-Related Corticosteroid Insufficiency
11 Chapter 11: Acute Coronary Syndromes & Cardiac Arrhythmias
11.1 Acute Coronary Syndromes & Mechanical Complications of Myocardial Infarction 11.2 Critical Tachyarrhythmias: Atrial Fibrillation with RVR, VT & VF 11.3 Critical Bradyarrhythmias, Conduction Blocks & Temporary Cardiac Pacing
12 Chapter 12: Acute Heart Failure, Valvular & Pericardial Emergencies
12.1 Acute Decompensated Heart Failure & Cardiogenic Pulmonary Edema 12.2 Acute Valvular Regurgitation & Prosthetic Valve Emergencies 12.3 Pericardial Tamponade & Acute Aortic Syndromes
13 Chapter 13: Myocardial Disease, Hypertensive & Cardiac Device Emergencies
13.1 Fulminant Myocarditis, Stress & Peripartum Cardiomyopathy, and Hypertrophic Cardiomyopathy 13.2 Hypertensive Emergencies & Ruptured Abdominal Aortic Aneurysm 13.3 Implanted Cardiac Devices, LVAD Emergencies & Electrical Storm
14 Chapter 14: Sepsis & Systemic Infectious Diseases
14.1 Sepsis-3 Definitions & Surviving Sepsis Campaign 2026 Guidelines 14.2 Refractory Septic Shock & Adjunctive Therapies 14.3 Multidrug-Resistant Pathogens & Antimicrobial Stewardship in the ICU
15 Chapter 15: ICU-Acquired & Severe Focal Infections
15.1 Hospital-Acquired & Ventilator-Associated Pneumonia 15.2 Central Line-Associated Bloodstream Infections & Catheter-Associated UTIs 15.3 Intra-Abdominal Sepsis, Necrotizing Soft Tissue Infections & CNS Infections
16 Chapter 16: Focal, Special-Host & Systemic Infections
16.1 CNS Infections Beyond Bacterial Meningitis: Encephalitis, Brain Abscess & Epidural Abscess 16.2 Infections in the Immunocompromised Host, Tropical & Bioterror Infections 16.3 Infective Endocarditis, Device Infections & Other Focal Cardiovascular Infections 16.4 Antimicrobial Pharmacokinetics, Allergy, Toxicity & Infection Prevention 16.5 Gastrointestinal & Hepatobiliary Infections: Fulminant C. difficile, Typhlitis, CMV Colitis & Abscesses
17 Chapter 17: Neurocritical Care & Coma
17.1 Coma, Altered Mental Status & Acute Delirium in the ICU 17.2 Status Epilepticus & Non-Convulsive Status Epilepticus 17.3 Acute Ischemic Stroke & Intracranial Hemorrhage
18 Chapter 18: Cerebrovascular Syndromes, Encephalopathy & Withdrawal States
18.1 Cerebral Venous Sinus Thrombosis, PRES & Reversible Cerebral Vasoconstriction Syndrome 18.2 Alcohol & Sedative Withdrawal, Wernicke Encephalopathy & Drug-Induced Encephalopathy
19 Chapter 19: Intracranial Hypertension & Neuromuscular Weakness
19.1 Intracranial Pressure Monitoring, Cerebral Perfusion & Tiered ICP Management 19.2 Acute Neuromuscular Respiratory Failure, ICU-Acquired Weakness & Brain Death Determination
20 Chapter 20: Traumatic Brain Injury, Spinal Cord Injury & Toxin-Mediated Paralysis
20.1 Traumatic Brain Injury Management & Paroxysmal Sympathetic Hyperactivity 20.2 Acute Spinal Cord Injury, Neurogenic Shock & Autonomic Dysreflexia 20.3 Toxin-Mediated Paralysis & Neuromuscular Crises: Botulism, Tetanus, Tick Paralysis & Myasthenic Crisis
21 Chapter 21: Gastrointestinal, Hepatic & Abdominal Emergencies
21.1 Acute Upper & Lower Gastrointestinal Bleeding in the ICU 21.2 Acute Liver Failure & Severe Acute Pancreatitis 21.3 Abdominal Compartment Syndrome & Acute Mesenteric Ischemia
22 Chapter 22: Luminal GI Emergencies & Complications of Cirrhosis
22.1 Esophageal, Gastric & Bowel Emergencies: Perforation, Obstruction, Ogilvie Syndrome & Colonic Ischemia 22.2 Complications of Cirrhosis: Alcohol-Associated Hepatitis, Hepatorenal Syndrome & Pulmonary Vascular Syndromes
23 Chapter 23: Trauma, Burns & Perioperative Critical Care
23.1 Polytrauma Resuscitation, Damage Control & Massive Transfusion 23.2 Severe Burn Injury, Inhalation Injury & Environmental Emergencies 23.3 Perioperative Critical Care for High-Risk Surgical Patients
24 Chapter 24: Thoracic Trauma, Environmental Injury & Obstetric Critical Care
24.1 Thoracic Trauma: Flail Chest, Pulmonary Contusion, Great Vessel & Tracheobronchial Injury 24.2 Environmental Injury: Drowning, Diving, Altitude, Heat, Cold, Electrical & Radiation 24.3 Obstetric & Genitourinary Emergencies and the Physiology of Pregnancy
25 Chapter 25: Transplantation, Donor Management & Post-Cardiac Surgery Care
25.1 Solid Organ Transplant Recipients & Deceased Donor Management 25.2 Post-Cardiac Surgery Critical Care: Bleeding, Tamponade, Low Output & Vasoplegia
26 Chapter 26: Hematologic Emergencies, Toxicology, Critical Ultrasound & ICU Liberation
26.1 Hematologic Emergencies in the ICU: HIT, DIC, TMA & Anticoagulant Reversal 26.2 Critical Care Toxicology, Toxidromes & Specific Antidotes 26.3 Critical Care Point-of-Care Ultrasound (POCUS) 26.4 ICU Liberation, Analgosedation, Goals of Care & Critical Care Ethics
27 Chapter 27: Transfusion Medicine, Hematologic & Oncologic Disorders
27.1 Transfusion Medicine: Products, Thresholds, Reactions & Apheresis 27.2 Red and White Cell Disorders, Hemoglobinopathies, Factor Deficiencies & Hypercoagulable States 27.3 Oncologic Emergencies, Hematopoietic Cell Transplant Complications & Cellular Therapy Toxicity
28 Chapter 28: Clinical Pharmacology, Adverse Drug Reactions & Specific Poisonings
28.1 Pharmacokinetic Principles, Dose Adjustment & Drug Interactions in Critical Illness 28.2 Adverse Drug Reactions: Anaphylaxis, Severe Cutaneous Reactions & Hyperthermic Syndromes 28.3 Specific Poisonings: Sodium-Channel Blockers, Lithium, Valproate, Theophylline, Iron, Sulfonylureas & Methemoglobinemia
29 Chapter 29: Ethics, Research Methods, Administration & Abdominal Ultrasound
29.1 Advance Care Planning, Nonbeneficial Treatment, Informed Consent & Confidentiality 29.2 Critical Care Research Methods, Statistics, IRB Oversight & Quality Improvement 29.3 Abdominal, Vascular & Procedural Point-of-Care Ultrasound
20.2 Acute Spinal Cord Injury, Neurogenic Shock & Autonomic Dysreflexia
Key Takeaways Explain This Topic AI
Neurogenic shock from injury above T6 produces hypotension with bradycardia and warm extremities, in contrast to hemorrhagic shock, which produces tachycardia and vasoconstriction.
Guidelines suggest maintaining mean arterial pressure at 85 to 90 mmHg for the first 5 to 7 days after acute spinal cord injury to support cord perfusion.
High-dose methylprednisolone is not recommended for acute spinal cord injury, because the evidence of benefit is weak and infection and hyperglycemia increase.
Autonomic dysreflexia in injury at or above T6 presents with severe hypertension and bradycardia with headache and flushing above the lesion; first steps are sitting the patient upright and relieving bladder or bowel distension.
Succinylcholine is avoided from about 48 to 72 hours after spinal cord injury because denervation upregulates acetylcholine receptors and can cause fatal hyperkalemia.
Last updated: October 2026
Immediate Assessment
Immobilize until the spine is cleared; log-roll and maintain in-line stabilization during airway management. Awake fiberoptic or video laryngoscopy with manual in-line stabilization is preferred in an unstable cervical spine.
Respiratory failure depends on the level:
Above C3 to C5 ("C3, 4, 5 keep the diaphragm alive"): diaphragmatic paralysis requiring ventilation.
C5 to C8 : preserved diaphragm with loss of intercostal and abdominal muscle function, so vital capacity falls, cough is weak, and secretions accumulate. Deterioration occurs over the first days as edema ascends and fatigue sets in. Follow vital capacity and negative inspiratory force , and intubate early rather than after a crisis.
Ventilated patients with high cervical injury often improve in the supine position, which is the opposite of most respiratory failure, because the abdominal contents push the paralyzed diaphragm upward and improve its mechanics.
ASIA classification : examine motor and sensory levels, sacral sparing, and the bulbocavernosus reflex; complete injury (ASIA A) versus incomplete injury changes prognosis.
Imaging : CT of the whole spine for fracture; MRI for cord signal change, ligamentous injury, and compression, especially with neurologic deficit and a normal CT.
Neurogenic Shock Versus Spinal Shock
These two terms are frequently confused.
- Neurogenic shock Spinal shock
- Nature A hemodynamic syndrome A neurologic syndrome
Mechanism Loss of sympathetic outflow from injury above about T6, with intact vagal tone Transient depression of cord reflexes below the injury
Findings Hypotension with bradycardia , warm and well-perfused skin, and low systemic vascular resistance Flaccid paralysis, areflexia , absent bulbocavernosus reflex, and urinary retention
Course Days to weeks; resolves as vascular tone returns Reflexes return over days to weeks, often evolving into spasticity
Treatment of neurogenic shock :
Exclude hemorrhage first . A trauma patient can have both; hemorrhagic shock gives tachycardia and cool extremities, so bradycardia with warm skin points to neurogenic shock.
Volume to euvolemia, avoiding overload.
Vasopressors with chronotropic support : norepinephrine is commonly used; dopamine or epinephrine help when bradycardia dominates. Phenylephrine raises pressure but can worsen reflex bradycardia.
Atropine for symptomatic bradycardia, with temporary pacing for refractory bradyarrhythmia or arrest during suctioning.
Mean arterial pressure target of 85 to 90 mmHg for the first 5 to 7 days to support cord perfusion, which guidelines suggest while acknowledging limited high-quality evidence.
Watch for profound bradycardia or asystole during tracheal suctioning , a vagally mediated reflex in high cervical injury; pre-oxygenate and consider atropine.
Interventions With and Without Evidence
Steroids : high-dose methylprednisolone is not recommended . The NASCIS trials' claimed benefits came from post hoc subgroups, and steroids increase pneumonia, sepsis, hyperglycemia, and gastrointestinal bleeding.
Timing of surgical decompression : early decompression (within about 24 hours) is associated with better neurologic recovery in observational and some prospective data and is generally pursued when the patient can tolerate it.
Thromboprophylaxis : the risk of venous thromboembolism is very high. Start low-molecular-weight heparin within about 72 hours once bleeding risk allows, plus mechanical prophylaxis. Inferior vena cava filters are not routine.
Stress ulcer prophylaxis and bowel and bladder programs begin immediately; neurogenic bladder requires intermittent or indwelling catheterization.
Pressure injury prevention : turning schedules and specialty surfaces from day one.
Succinylcholine : safe within the first 24 to 48 hours, then avoided from about 48 to 72 hours after injury for up to a year or more, because upregulated extrajunctional acetylcholine receptors cause massive potassium release and cardiac arrest.
Temperature dysregulation : poikilothermia below the lesion impairs both heat generation and dissipation.
Specific Incomplete Cord Syndromes
Syndrome Mechanism Findings
Central cord Hyperextension in cervical spondylosis; the commonest incomplete syndrome Weakness worse in the upper than the lower limbs, with sacral sparing and variable sensory loss
Anterior cord Anterior spinal artery infarction (aortic surgery, dissection, hypotension) Paraplegia with loss of pain and temperature; proprioception and vibration preserved
Brown-Sequard Hemicord injury (penetrating trauma) Ipsilateral motor and proprioceptive loss, contralateral pain and temperature loss
Posterior cord Rare; B12 deficiency, trauma Loss of proprioception and vibration with preserved strength
Conus medullaris and cauda equina Lower lesions; cauda equina is a lower motor neuron syndrome Saddle anesthesia, urinary retention, areflexia; cauda equina compression is a surgical emergency
Autonomic Dysreflexia
Autonomic dysreflexia occurs in chronic injury at or above T6 (usually after spinal shock resolves). A noxious stimulus below the lesion triggers unopposed sympathetic outflow, because descending inhibitory pathways are interrupted.
Presentation :
Severe hypertension (a rise of 20 to 40 mmHg above the patient's low baseline is significant; systolic pressures above 200 mmHg occur).
Reflex bradycardia from intact baroreceptor input to the vagus.
Above the lesion : pounding headache, flushing, sweating, and nasal congestion.
Below the lesion : pallor, cool skin, piloerection.
Triggers (most to least common): bladder distension or catheter blockage , fecal impaction , pressure injury, ingrown toenail, fracture, acute abdomen, labor, and procedures such as cystoscopy.
Complications : hypertensive encephalopathy, intracranial hemorrhage, seizures, retinal hemorrhage, pulmonary edema, and arrhythmia.
Management, in order :
Sit the patient upright and lower the legs to use orthostatic pooling.
Loosen clothing and abdominal binders .
Check the bladder : catheterize, or irrigate or replace a blocked catheter using lidocaine jelly.
Check for fecal impaction after applying topical anesthetic, because the examination itself can worsen the episode.
Antihypertensives if the pressure remains very high: a short-acting agent such as nitroglycerin paste (easily removed once the pressure falls, and avoided if a phosphodiesterase-5 inhibitor has been taken), nifedipine (immediate-release, bite-and-swallow), captopril, or an IV infusion of nicardipine or clevidipine for severe cases.
Search for and remove the trigger , then continue monitoring, because recurrence is common.
Prevention : scheduled bladder and bowel programs, skin care, pre-procedural anesthesia and prophylaxis, and patient education with a wallet card. Pregnancy and labor in women with high injury require planned regional anesthesia.
Warning
Do not treat autonomic dysreflexia as essential hypertension with long-acting agents. When the trigger is relieved, blood pressure falls abruptly, and a long-acting antihypertensive then causes profound hypotension in a patient with no sympathetic reserve.