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Autonomic dysreflexia

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Autonomic dysreflexia
Other namesAutonomic hyperreflexia[1]
SpecialtyNeurology Edit this on Wikidata

Autonomic dysreflexia (AD) is a potentially fatal medical emergency classically characterized by uncontrolled hypertension and cardiac arrhythmia.[2][3][4] AD occurs most often in individuals with spinal cord injuries with lesions at or above the T6 spinal cord level, although it has been reported in patients with lesions as low as T10.[5] Guillain–Barré syndrome may also cause autonomic dysreflexia.[1]

The uncontrolled hypertension in AD may result in mild symptoms, such as sweating above the lesion level, goosebumps, blurred vision, or headache; however, severe symptoms may result in potentially life-threatening complications including seizure, intracranial bleed (stroke), myocardial infarction, and retinal detachment.[2]

AD is triggered by either noxious or non-noxious stimuli, resulting in sympathetic stimulation and hyperactivity.[6] The most common causes include bladder or bowel over-distension from urinary retention and fecal compaction,[7] pressure sores, extreme temperatures, fractures, undetected painful stimuli (such as a pebble in a shoe), sexual activity, and extreme spinal cord pain. The noxious stimuli activates a sympathetic surge that transmits through intact peripheral nerves, resulting in systemic vasoconstriction below the level of the spinal cord lesion.[8] The peripheral arterial vasoconstriction and hypertension activates the baroreceptors, resulting in a parasympathetic surge originating in the central nervous system to inhibit the sympathetic outflow; however, the parasympathetic signal is unable to transmit below the level of the spinal cord lesion and is insufficient to reduce elevated blood pressure.[8] This results in bradycardia, tachycardia, vasodilation, flushing, pupillary constriction and nasal stuffiness above the spinal lesion, while there is piloerection, pale and cool skin below the lesion due to the prevailing sympathetic outflow.[8] Bradycardia is a common symptom though some patients may experience tachycardia instead.

Autonomic dysreflexia should be treated immediately by removing or correcting the noxious stimuli. This involves sitting the patient upright, removing any constrictive clothing (including abdominal binders and support stockings), rechecking blood pressure frequently, and then checking for and removing the inciting issue, which may require urinary catheterization or bowel disimpaction.[2][4] If systolic blood pressure remains elevated (over 150 mm Hg) after initial steps, fast-acting short-duration antihypertensives are considered,[9] while other inciting causes must be investigated for the symptoms to resolve.[2]

Prevention of AD involves educating the patient, family and caregivers of the precipitating cause, if known, and how to avoid it, as well as other triggers.[4] Since bladder and bowel are common causes, routine bladder and bowel programs and urological follow-up for cystoscopy/urodynamic studies may help reduce the frequency and severity of attacks.[2]

Signs and symptoms

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This condition is distinct and usually episodic. Common presenting symptoms include headache, diaphoresis, and increased blood pressure. Patients may also experience facial erythema, goosebumps, nasal stuffiness, a "feeling of doom" or apprehension, and blurred vision.[5] An elevation of 20 mm Hg over baseline systolic blood pressure, with a potential source below the neurological level of injury, meets the current definition of dysreflexia.[10]

Complications

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Autonomic dysreflexia can become chronic and recurrent, often in response to longstanding medical problems like soft tissue pressure injuries or hemorrhoids. Long term therapy may include alpha blockers or calcium channel blockers.[11]

Complications of severe acute hypertension can include seizures, pulmonary edema, myocardial infarction, or cerebral hemorrhage. Additional organs that may be affected include the kidneys and retinas of the eyes.[5]

Causes

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The first episode of autonomic dysreflexia may occur weeks to years after spinal cord injury takes place, but most people at risk develop their first episode within the first year after injury.[12]

There are many possible triggers of AD, though the most common causative factor is bladder distention.[13] Other causes include urinary tract infection, urinary retention, blocked catheters, constipation, hemorrhoids or fissures, skin damage, fractures, and sexual intercourse. Not all noxious stimuli will cause AD. Some otherwise severe noxious stimuli, e.g. broken bones, may not result in AD, and may in fact even go unnoticed. In the absence of clear triggering factors, episodes of AD that are recurrent can be important signs that there is an undetected underlying pathology in a patient that has not yet been elucidated.[14][15]

Mechanism

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Supraspinal vasomotor neurons send projections to the intermediolateral cell column, which is composed of sympathetic preganglionic neurons (SPN) through the T1-L2 segments.[7] The supraspinal neurons act on the SPN and its tonic firing, modulating its action on the peripheral sympathetic chain ganglia and the adrenal medulla.[7] The sympathetic ganglia act directly on the blood vessels they innervate throughout the body, controlling vessel diameter and resistance, while the adrenal medulla indirectly controls the same action through the release of epinephrine and norepinephrine.[7] In a patient with a spinal cord lesion, the descending autonomic pathways that are responsible for the supraspinal communication with the SPN are interrupted, resulting in decreased sympathetic outflow below the level of the injury.[7] In this circumstance, the SPN is controlled only by spinal influences.[7] After a spinal injury, the decreased sympathetic outflow causes reduced blood pressure and sympathetic reflex.[7] Eventually, synaptic reorganization and plasticity of SPN develops into an overly sensitive state, which results in abnormal reflex activation of SPN due to afferent stimuli, such as bowel or bladder distension.[7] Reflex activation then results in systemic vasoconstriction below the spinal cord disruption. This peripheral arterial vasoconstriction and hypertension activates the baroreceptors, resulting in a parasympathetic surge originating in the central nervous system which inhibits the sympathetic outflow; however, the parasympathetic signal is unable to transmit below the level of the spinal cord lesion.[8] This results in vasodilation, flushing, pupillary constriction and nasal stuffiness above the spinal lesion, contrasted with piloerection, paleness, and cool skin below the lesion due to the prevailing sympathetic outflow.[8] This issue is much more prominent for lesions at or above the T6 level because the splanchnic nerves emerge from the T5 level and below.

Diagnosis

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Diagnosis of AD is made by measuring an increase in systolic blood pressure greater than 20 to 30mmHg. The associated symptoms vary from life-threatening to asymptomatic.[16] Autonomic dysreflexia differs from autonomic instability, the various modest cardiac and neurological changes that accompany a spinal cord injury, including bradycardia, orthostatic hypotension, and ambient temperature intolerance. Because of this, elevated blood pressures in patients with baseline hypotension may not be recognized unless compared with their baseline levels. Diagnosis of AD may be differentiated by additional symptoms in addition to hypertension, including sweating, spasms, erythema (more likely in upper extremities), headaches, and blurred vision. Older patients with very incomplete spinal cord injuries and systolic hypertension without symptoms may be experiencing essential hypertension, not autonomic dysreflexia.

Treatment

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Initial management of AD includes measuring and monitoring blood pressures and sitting the patient upright to attempt to lower blood pressure as well as searching for and correcting the triggering stimuli. Tight clothing and stockings should be removed. Catheterization of the bladder should be performed as well as evaluation for possible urinary tract infection (UTI). Relief of a blocked urinary catheter tube may resolve the problem, and indwelling catheters should be checked for obstruction. A rectal examination can be performed to clear the rectum of any possible stool impaction. If the noxious precipitating trigger cannot be identified, prompt pharmacologic treatment may be needed to decrease elevating intracranial pressure until further studies can identify the cause.[17]

Drug treatment includes the rapidly acting vasodilators, including sublingual or topical nitrates or oral hydralazine or clonidine. Ganglionic blockers are also used to control sympathetic nervous system outflow.[18][9] Epidural anesthesia has been demonstrated to be effective in reducing AD in women in labor, though there is less evidence for its use in reducing AD during general surgical procedures.[19]

Prognosis

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Mortality is rare with AD, but morbidity such as stroke, retinal hemorrhage and pulmonary edema if left untreated can be quite severe. The cause of autonomic dysreflexia itself can be life-threatening, and must also be completely investigated and treated appropriately to prevent unnecessary morbidity and mortality.[16]

Attacks can be prevented by recognizing and avoiding triggering stimuli. Because bladder distension is a common trigger of AD, botulinum toxin used to treat bladder dysfunction in SCI may be effective in reducing attacks. Prophylactic use of nifedipine, prazosin, and terazosin has also been reported to prevent attacks.[11] Topical analgesics such as lidocaine and bupivacaine are also commonly used to reduce episodes of AD triggered by bowel and bladder management, though their effectiveness in reducing AD remains inconclusive.[20]

References

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  1. ^ a b "Autonomic dysreflexia". Medline. NIH. Retrieved 19 March 2019.
  2. ^ a b c d e Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, Bradley WG (2016). Bradley's neurology in clinical practice (Seventh ed.). London: Elsevier. ISBN 978-0-323-28783-8. OCLC 932031625.
  3. ^ Solinsky R, Kirshblum SC, Burns SP (September 2018). "Exploring detailed characteristics of autonomic dysreflexia". The Journal of Spinal Cord Medicine. 41 (5): 549–555. doi:10.1080/10790268.2017.1360434. PMC 6127514. PMID 28784041.
  4. ^ a b c Consortium for Spinal Cord Medicine (2002). "Acute management of autonomic dysreflexia: individuals with spinal cord injury presenting to health-care facilities". The Journal of Spinal Cord Medicine. 25 (Suppl 1): S67–S88. PMID 12051242.
  5. ^ a b c Vallès M, Benito J, Portell E, Vidal J (December 2005). "Cerebral hemorrhage due to autonomic dysreflexia in a spinal cord injury patient". Spinal Cord. 43 (12): 738–740. doi:10.1038/sj.sc.3101780. PMID 16010281.
  6. ^ Krassioukov A, Warburton DE, Teasell R, Eng JJ (April 2009). "A systematic review of the management of autonomic dysreflexia after spinal cord injury". Archives of Physical Medicine and Rehabilitation. 90 (4): 682–695. doi:10.1016/j.apmr.2008.10.017. PMC 3108991. PMID 19345787.
  7. ^ a b c d e f g h Eldahan KC, Rabchevsky AG (January 2018). "Autonomic dysreflexia after spinal cord injury: Systemic pathophysiology and methods of management". Autonomic Neuroscience. 209: 59–70. doi:10.1016/j.autneu.2017.05.002. PMC 5677594. PMID 28506502.
  8. ^ a b c d e Winn HR, ed. (30 November 2016). Youmans and Winn neurological surgery (Seventh ed.). Philadelphia, PA: Elsevier. ISBN 9780323287821. OCLC 963181140.
  9. ^ a b Solinsky R, Svircev JN, James JJ, Burns SP, Bunnell AE (November 2016). "A retrospective review of safety using a nursing driven protocol for autonomic dysreflexia in patients with spinal cord injuries". The Journal of Spinal Cord Medicine. 39 (6): 713–719. doi:10.1080/10790268.2015.1118186. PMC 5137561. PMID 26838482.
  10. ^ Krassioukov A, Biering-Sørensen F, Donovan W, Kennelly M, Kirshblum S, Krogh K, et al. (July 2012). "International standards to document remaining autonomic function after spinal cord injury". The Journal of Spinal Cord Medicine. 35 (4): 201–210. doi:10.1179/1079026812Z.00000000053. PMC 3425876. PMID 22925746.
  11. ^ a b Vaidyanathan S, Soni BM, Sett P, Watt JW, Oo T, Bingley J (November 1998). "Pathophysiology of autonomic dysreflexia: long-term treatment with terazosin in adult and paediatric spinal cord injury patients manifesting recurrent dysreflexic episodes". Spinal Cord. 36 (11): 761–770. doi:10.1038/sj.sc.3100680. PMID 9848483. S2CID 35222095.
  12. ^ de Andrade LT, de Araújo EG, Andrade K, de Souza DR, Garcia TR, Chianca TC (February 2013). "[Autonomic dysreflexia and nursing interventions for patients with spinal cord injury]". Revista da Escola de Enfermagem da U S P. 47 (1): 93–100. doi:10.1590/s0080-62342013000100012. PMID 23515808.
  13. ^ Allen KJ, Leslie SW (2022). "Autonomic Dysreflexia". StatPearls. Treasure Island (FL): StatPearls Publishing. PMID 29494041.
  14. ^ Burton AR, Brown R, Macefield VG (October 2008). "Selective activation of muscle and skin nociceptors does not trigger exaggerated sympathetic responses in spinal-injured subjects". Spinal Cord. 46 (10): 660–665. doi:10.1038/sc.2008.33. PMID 18427566.
  15. ^ Marsh DR, Weaver LC (June 2004). "Autonomic dysreflexia, induced by noxious or innocuous stimulation, does not depend on changes in dorsal horn substance p". Journal of Neurotrauma. 21 (6): 817–828. doi:10.1089/0897715041269605. PMID 15253807.
  16. ^ a b Wan D, Krassioukov AV (January 2014). "Life-threatening outcomes associated with autonomic dysreflexia: a clinical review". The Journal of Spinal Cord Medicine. 37 (1): 2–10. doi:10.1179/2045772313Y.0000000098. PMC 4066548. PMID 24090418.
  17. ^ Vaidyanathan, Subramanian; Soni, Bakul M.; Mansour, Paul; Oo, Tun (2017-11-02). "Fatal collapse due to autonomic dysreflexia during manual self-evacuation of bowel in a tetraplegic patient living alone: lessons to learn". International Medical Case Reports Journal. 10: 361–365. doi:10.2147/IMCRJ.S135586. PMC 5679675. PMID 29138603.
  18. ^ Solinsky R, Bunnell AE, Linsenmeyer TA, Svircev JN, Engle A, Burns SP (October 2017). "Pharmacodynamics and effectiveness of topical nitroglycerin at lowering blood pressure during autonomic dysreflexia". Spinal Cord. 55 (10): 911–914. doi:10.1038/sc.2017.58. PMID 28585557.
  19. ^ Petsas, Anna; Drake, Jeremy. "Perioperative management for patients with a chronic spinal cord injury". academic.oup.com. Retrieved 2023-10-26.
  20. ^ Gray, Katherine; Sheehan, Whitley; McCracken, Laura; Krogh, Klaus; Sachdeva, Rahul; Krassioukov, Andrei V. (12 August 2022). "Are local analgesics effective in reducing autonomic dysreflexia in individuals with spinal cord injury? A systematic review". Spinal Cord. 61 (1): 1–7. doi:10.1038/s41393-022-00840-8. ISSN 1476-5624. PMID 35962043.

Further reading

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