Autonomic HyperReflexia
AKA Autonomic Dysreflexia
By Meredith Bischoff BSN, RN, SRNA
Autonomic Hyperreflexia
- Occurs in patients with spinal cord injuries at or above the T6 level, due to the loss of supraspinal control of sympathetic nervous system activity.
- With injuries above T6, the splanchnic innervation is activated, causing splanchnic vasoconstriction, and resulting in more severe symptoms such as hypertension and compensatory bradycardia.
- A stimulus below the level of injury can trigger an exaggerated sympathetic discharge from the isolated spinal reflex arcs.
(Nagelhout & Elisha, 2022).
- Results in massive vasoconstriction below the lesion, causing acute hypertension.
- Baroreceptors in the carotid sinus (CN9) and aortic arch (CN10) sense the elevated blood pressure and stimulate parasympathetic outflow via the vagus nerve, leading to reflex bradycardia and vasodilation above the level of injury.
Hallmark presentation of: severe hypertension, headache, flushing, and bradycardia
SNS vs PNS
CraniosacralCN III, VII, IX, X and S2–S4Rest and digestHR, GI motility, pupil constriction, promotes bladder emptyingNeurotransmitter preganglionic = acetylcholine postganglionic = acetylcholine Dominates at rest and balances SNS activity.
Thoracolumbar T1–L2Fight or flight HR, vasoconstriction, bronchodilation, pupil dilationNeurotransmitterspreganglionic = acetylcholine postganglionic = norepinephrineControls vascular tone, leads to baseline BP maintenance.
The hypothalamus and brain stem send inhibitory signals down the spinal cord preventing exaggerated responses to peripheral stimuli.
(Nagelhout & Elisha, 2022).
What Apex Says About AH
post-op
Anesthesia
Treatment
AH may present post op as anesthesia wears off. Close post op monitoring.
Removal of stimulusDeepen anesthetic Clevidipine, Nicardipine IV infusion (2.5–15 mg/hr), Nitrates Hydralazine
Spinal General
Apex Anesthesia, 2025
Case Presentation
32 yo F brought into OR for total laparoscopic hysterectomy.Preop vitals: HR 54, BP 104/72, SPO2 100% (on RA) History: ATV accident in 2024 C2-T1 spinal cord injury, prolonged ICU stay, prior tracheostomy (healed), no sensation or movement from chest down, has gross motor in arms, but no fine motor control. Anesthetic plan: GETA, bilateral quadratus lumborum blocks Anesthesia and the surgeon spoke with the patient and discussed the possibility that the surgery may not happen if anesthesia felt unsafe after induction. Everyone agreed. Induction: Fentanyl, Propofol, Rocuronium. TIVA for maintinance. Patient was intubated successfully using a McGrath and 6.0 tube. While QL blocks were bring placed, the patient developed a patchy rash all over abdomen. Blood pressure kept rising and was treated with higher doses of Propofol (max was 175 mcg/kg/min), 50-100mcg boluses of Nitroglycerin and eventually a Nitroglycerine gtt and Cardene gtt were started. Blood pressure remained 180s/110s. After a conversation with the surgeon, the decision was made to abort the procedure. An arterial line was placed, the patient was woken up, extubted and then transferred to the ICU.
Studies
Are urological procedures in tetraplegic patients safely performed without anesthesia? A report of three cases.-3 patients who developed autonomic dysreflexia when cystoscopy and laser lithotripsy were carried out without anesthesia. - Subrachnoid block or epidural meperidine blocks nociceptive impulses from urinary bladder and prevents occurrence of autonomic dysreflexia. Vaidyanathan, S., Soni, B., Selmi, F., Singh, G., Esanu, C., Hughes, P., Oo, T., & Pulya, K. (2012). Are urological procedures in tetraplegic patients safely performed without anesthesia? A report of three cases. Patient Safety in Surgery, 6, 3. https://doi.org/10.1186/1754-9493-6-3 Case Report: Anesthetic Management of Cesarean Section in a Patient With Paraplegia -Intrathecal block is the preferred choice for women with paraplegia who require cesarean section if the lumbar bone structure allows puncture attempts. Intrathetcal anesthesia prevents AHR more effectively than general anesthesia. Su, Y., Lei, X., & Yu, J. (2022). Case report: Anesthetic management of cesarean section in a patient with paraplegia. Frontiers in Medicine, 9, 783796. https://doi.org/10.3389/fmed.2022.783796
Evaluation and Management of Autonomic Dysreflexia and Other Autonomic Dysfunctions: Preventing the Highs and Lows -Local anesthetic in the subarachnoid space produces a dense, predictable segmental block that: (1) blocks afferent sensory input from pelvic/lower-body organs and (2) blocks preganglionic sympathetic efferents (functional “sympathectomy”) below the block. With the afferent trigger and the efferent outflow both interrupted, the dysreflexic surge is prevented. Krassioukov, A., Linsenmeyer, T. A., Beck, L. A., Elliott, S., Gorman, P., Kirshblum, S., Vogel, L., Wecht, J., & Clay, S. (2021). Evaluation and Management of Autonomic Dysreflexia and Other Autonomic Dysfunctions: Preventing the Highs and Lows: Management of Blood Pressure, Sweating, and Temperature Dysfunction. Topics in spinal cord injury rehabilitation, 27(2), 225–290. https://doi.org/10.46292/sci2702-225 Regional anesthesia techniques in patients with chronic spinal cord injury - Literature review -28 studies Regional anesthesia may be particularly useful for patients with SCI. It may be used for upper and lower limb surgery, abdominal surgery, and obstetrics and particularly for the prevention of autonomic dysreflexia. Tzima C, Vlamis I. Regional anesthesia techniques in patients with chronic spinal cord injury. Acta Orthopaedica et Traumatologica Hellenica. 2021;72(4):414-419.
References
APEX Anesthesia. (n.d.). APEX Anesthesia review. https://www.apexanesthesia.com Elisha, S., Heiner, J. S., & Nagelhout, J. J. (2022). Nurse anesthesia (7th ed.). Elsevier. Krassioukov, A., Linsenmeyer, T. A., Beck, L. A., Elliott, S., Gorman, P., Kirshblum, S., Vogel, L., Wecht, J., & Clay, S. (2021). Evaluation and Management of Autonomic Dysreflexia and Other Autonomic Dysfunctions: Preventing the Highs and Lows: Management of Blood Pressure, Sweating, and Temperature Dysfunction. Topics in spinal cord injury rehabilitation, 27(2), 225–290. https://doi.org/10.46292/sci2702-225 Su, Y., Lei, X., & Yu, J. (2022). Case report: Anesthetic management of cesarean section in a patient with paraplegia. Frontiers in Medicine, 9, 783796. https://doi.org/10.3389/fmed.2022.783796 Tzima C, Vlamis I. Regional anesthesia techniques in patients with chronic spinal cord injury. Acta Orthopaedica et Traumatologica Hellenica. 2021;72(4):414-419. Vaidyanathan, S., Soni, B., Selmi, F., Singh, G., Esanu, C., Hughes, P., Oo, T., & Pulya, K. (2012). Are urological procedures in tetraplegic patients safely performed without anesthesia? A report of three cases. Patient Safety in Surgery, 6, 3. https://doi.org/10.1186/1754-9493-6-3
Autonomic HyperReflexia
Meredith Bischoff
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Transcript
Autonomic HyperReflexia
AKA Autonomic Dysreflexia
By Meredith Bischoff BSN, RN, SRNA
Autonomic Hyperreflexia
(Nagelhout & Elisha, 2022).
Hallmark presentation of: severe hypertension, headache, flushing, and bradycardia
SNS vs PNS
CraniosacralCN III, VII, IX, X and S2–S4Rest and digestHR, GI motility, pupil constriction, promotes bladder emptyingNeurotransmitter preganglionic = acetylcholine postganglionic = acetylcholine Dominates at rest and balances SNS activity.
Thoracolumbar T1–L2Fight or flight HR, vasoconstriction, bronchodilation, pupil dilationNeurotransmitterspreganglionic = acetylcholine postganglionic = norepinephrineControls vascular tone, leads to baseline BP maintenance.
The hypothalamus and brain stem send inhibitory signals down the spinal cord preventing exaggerated responses to peripheral stimuli.
(Nagelhout & Elisha, 2022).
What Apex Says About AH
post-op
Anesthesia
Treatment
AH may present post op as anesthesia wears off. Close post op monitoring.
Removal of stimulusDeepen anesthetic Clevidipine, Nicardipine IV infusion (2.5–15 mg/hr), Nitrates Hydralazine
Spinal General
Apex Anesthesia, 2025
Case Presentation
32 yo F brought into OR for total laparoscopic hysterectomy.Preop vitals: HR 54, BP 104/72, SPO2 100% (on RA) History: ATV accident in 2024 C2-T1 spinal cord injury, prolonged ICU stay, prior tracheostomy (healed), no sensation or movement from chest down, has gross motor in arms, but no fine motor control. Anesthetic plan: GETA, bilateral quadratus lumborum blocks Anesthesia and the surgeon spoke with the patient and discussed the possibility that the surgery may not happen if anesthesia felt unsafe after induction. Everyone agreed. Induction: Fentanyl, Propofol, Rocuronium. TIVA for maintinance. Patient was intubated successfully using a McGrath and 6.0 tube. While QL blocks were bring placed, the patient developed a patchy rash all over abdomen. Blood pressure kept rising and was treated with higher doses of Propofol (max was 175 mcg/kg/min), 50-100mcg boluses of Nitroglycerin and eventually a Nitroglycerine gtt and Cardene gtt were started. Blood pressure remained 180s/110s. After a conversation with the surgeon, the decision was made to abort the procedure. An arterial line was placed, the patient was woken up, extubted and then transferred to the ICU.
Studies
Are urological procedures in tetraplegic patients safely performed without anesthesia? A report of three cases.-3 patients who developed autonomic dysreflexia when cystoscopy and laser lithotripsy were carried out without anesthesia. - Subrachnoid block or epidural meperidine blocks nociceptive impulses from urinary bladder and prevents occurrence of autonomic dysreflexia. Vaidyanathan, S., Soni, B., Selmi, F., Singh, G., Esanu, C., Hughes, P., Oo, T., & Pulya, K. (2012). Are urological procedures in tetraplegic patients safely performed without anesthesia? A report of three cases. Patient Safety in Surgery, 6, 3. https://doi.org/10.1186/1754-9493-6-3 Case Report: Anesthetic Management of Cesarean Section in a Patient With Paraplegia -Intrathecal block is the preferred choice for women with paraplegia who require cesarean section if the lumbar bone structure allows puncture attempts. Intrathetcal anesthesia prevents AHR more effectively than general anesthesia. Su, Y., Lei, X., & Yu, J. (2022). Case report: Anesthetic management of cesarean section in a patient with paraplegia. Frontiers in Medicine, 9, 783796. https://doi.org/10.3389/fmed.2022.783796
Evaluation and Management of Autonomic Dysreflexia and Other Autonomic Dysfunctions: Preventing the Highs and Lows -Local anesthetic in the subarachnoid space produces a dense, predictable segmental block that: (1) blocks afferent sensory input from pelvic/lower-body organs and (2) blocks preganglionic sympathetic efferents (functional “sympathectomy”) below the block. With the afferent trigger and the efferent outflow both interrupted, the dysreflexic surge is prevented. Krassioukov, A., Linsenmeyer, T. A., Beck, L. A., Elliott, S., Gorman, P., Kirshblum, S., Vogel, L., Wecht, J., & Clay, S. (2021). Evaluation and Management of Autonomic Dysreflexia and Other Autonomic Dysfunctions: Preventing the Highs and Lows: Management of Blood Pressure, Sweating, and Temperature Dysfunction. Topics in spinal cord injury rehabilitation, 27(2), 225–290. https://doi.org/10.46292/sci2702-225 Regional anesthesia techniques in patients with chronic spinal cord injury - Literature review -28 studies Regional anesthesia may be particularly useful for patients with SCI. It may be used for upper and lower limb surgery, abdominal surgery, and obstetrics and particularly for the prevention of autonomic dysreflexia. Tzima C, Vlamis I. Regional anesthesia techniques in patients with chronic spinal cord injury. Acta Orthopaedica et Traumatologica Hellenica. 2021;72(4):414-419.
References
APEX Anesthesia. (n.d.). APEX Anesthesia review. https://www.apexanesthesia.com Elisha, S., Heiner, J. S., & Nagelhout, J. J. (2022). Nurse anesthesia (7th ed.). Elsevier. Krassioukov, A., Linsenmeyer, T. A., Beck, L. A., Elliott, S., Gorman, P., Kirshblum, S., Vogel, L., Wecht, J., & Clay, S. (2021). Evaluation and Management of Autonomic Dysreflexia and Other Autonomic Dysfunctions: Preventing the Highs and Lows: Management of Blood Pressure, Sweating, and Temperature Dysfunction. Topics in spinal cord injury rehabilitation, 27(2), 225–290. https://doi.org/10.46292/sci2702-225 Su, Y., Lei, X., & Yu, J. (2022). Case report: Anesthetic management of cesarean section in a patient with paraplegia. Frontiers in Medicine, 9, 783796. https://doi.org/10.3389/fmed.2022.783796 Tzima C, Vlamis I. Regional anesthesia techniques in patients with chronic spinal cord injury. Acta Orthopaedica et Traumatologica Hellenica. 2021;72(4):414-419. Vaidyanathan, S., Soni, B., Selmi, F., Singh, G., Esanu, C., Hughes, P., Oo, T., & Pulya, K. (2012). Are urological procedures in tetraplegic patients safely performed without anesthesia? A report of three cases. Patient Safety in Surgery, 6, 3. https://doi.org/10.1186/1754-9493-6-3