Autonomic Dysreflexia 

Why is this important to health care professionals?

  • AD is a very unique phenomenon in SCI/D and can cause sudden and severe complications necessitating prompt treatment.
  • AD is important on two accounts:
    • Lack of awareness of the condition among healthcare professionals
    • Fatal consequences may develop in affected patient.
  • It is the medial professionals' responsibility to have a basic understanding of the nature of the condition and the simple steps to avoid the devastating complications associated with the condition.

Synonym

  • autonomic hyper-reflexi

Definition

  • An acute exaggerated, pathologic, autonomic reflex response involving
  • Overactivity of the thoraco-lumbar sympathetic cell mass.
  • In response to stimuli below the level of the lesion
  • Occurs in SCI patients with lesions above the level of T6-T8
  • Can be life threatening.

Facts and Epidemiology

  • Associated conditions of AD:
    • SCI:
      • The most common etiology, but only lesions above T6-8
      • Leaving sufficient sympathetic neurons below the lesion, out of neural contact with brain stem regulating centers for the syndrome to occur
    • Non-traumatic conditions:
      • Spinal cord tumors [Furlan 2003]
      • Prior neurosurgery above the level of T6 [Finestone 1993]
      • MS [Bateman 2002]
  • SCI lesion
    • Cervical (60%) > thoracic (20%)
  • Types of injury:
    • AD can develop in patients with both complete and incomplete lesions.
    • However symptoms are less common and less severe in patients with incomplete lesions [Kewalramani 1980].
  • Onset after SCI:
    • Variable (usually after spinal shock but may be years after SCI)
    • Chronic stage of SCI > acute stage
    • Patients with high and complete lesions may be at risk during the acute phase of SCI [Krassioukov 2003].
  • Clinical manifestation
    • Underreported but 50% -70% of patients with lesions at or above T6 [Shergill 1999; Lindan 1980]
    • Primarily affecting vascular and organ systems controlled by the sympathetic nervous system.
    • The most prominent component of AD: dramatic development of hypertension

Pathophysiologic mechanism

  • Normal reflex mechanism:
    • Normal sympathetic output from the spinal cord is modulated (inhibited) by input from the higher centers (medulla)
  • Pathological mechanism
    • Increased sympathetic reflex activity after synaptic re-organisation: afferent and efferent plasticity
    • As a result of the SCI, neural connections to higher centers are lost. There is no modulating effect derived from medullary centers on the sympathetic response to specific afferent stimuli ("autonomic imbalance"), and a generalized massive sympathetic discharge occurs.
    • Intact neuronal circuit distal to the level of injury is required for AD to occur.
    • AD would not occur, for example, after massive spinal cord infarction.
  • Sympathetic overactivity
    • Severe hypertension reflects involvement of a large vascular bed.
    • Autonomic imbalance leads to splanchnic vasoconstriction.
    • Splanchnic vasculature is under the neural control < T6-8
  • Compensatory mechanism:
    • Carotid baroreceptors are activated by the hypertension and this results in vagal nerve discharge
    • Bradycardia occurs driven by the vagal activity.
    • Patients also experience sweating, nasal congestion, and facial flushing in conjunction with the cardiac events driven by vagal discharge.

Symptoms (*The most common symptoms)

  • Predominant parasympathetic excitation above the level of injury
    • Flushing* above the level of the lesion: body above the lesion incl. face
    • Sweating* and chills
    • Bradycardia: tachycardia or arrhythmia may be present
    • Nasal congestion: secondary to vasodilatation
    • Malaise and nausea: secondary to parasympathetic/vagal effect
  • Sympathetic excitation below the level of injury
    • Sudden hypertension*:
      • Of varying severity
      • From causing a mild headache to life-threatening cerebral hemorrhage, seizure or even death if uncontrolled
    • Pounding headache*:
      • One of the commonest symptoms
      • From both vasodilatation and hypertension
  • Others
    • Anxiety
    • Blurred vision
    • Goosebumps (cutis anserine): below the level of the lesion
    • Urinary sphincter:
      • DSD
      • Smooth sphincter dyssynergia: also generally develops
  • Clinical implications:
    • Many patients are already familiar with the initial symptoms of AD. Lack of familiarity with these patterns of presentation may lead to a delay or errors in diagnosis and management.
    • During history taking, it is very important to ask the patient whether the patient experienced any AD episodes previously.
    • It is also important to check patient’s AD history during regular follow-up as the patient in acute stage of SCI may develop AD later.

Triggering stimuli

  • Any stimulus that causes an irritation or pain to the afferents below the level of injury.
  • Common stimuli are:
    • Urogenital organs:
      • Bladder distention:
        • Up to 85% of episodes
        • Catheter obstruction (kinked indwelling catheters or clot retention): the commonest causes
        • Reflex bladder contractility with detrusor sphincter dysynergia.
        • Bladder distention usually in the afternoon when the patient is up in a wheelchair
      • Urological interventions:
        • Lower urinary tract instrumentation: tube change, catheterization, urodynamic studies, cystoscopy, and interventional procedures for calculi, such as percutaneous nephrolithotomy or shock wave lithotripsy,
        • Assisted ejaculation: penile vibratory stimulation, or electroejaculation
      • Reflex erections and sexual activity
      • UTI
        • common in SCI patients
        • Therefore, it should be treated appropriately
    • Gastrointestinal pathology and instrumentation: second commonest category of cause
      • Fecal impaction or rectal distension
      • Anorectal conditions such as hemorrhoids and fissures
      • Proctoscopy or sigmoidoscopy
    • Others: pressure sores, cuts, burns, bruises, sunburn, pressure of any kind on the body, ingrown toenails, or tight clothing, long bone fracture
  • Clinical implications:
    • In case of minor short-duration stimuli, symptoms resolve quickly if the stimulus is withdrawn.
    • It is very important for the practitioners always to be aware of the fact that the following stimuli can cause risks of the developing AD before initiating any procedures.

Treatment

  • The management of AD is quite straightforward.
  • First step of treatment
    • Changing position: sitting upright for orthostatic decrease in blood pressure
    • Removing or loosening tight clothing such as tight belts
    • Monitoring blood pressure closely
    • Emptying the bladder or bowels immediately
  • Second step of treatment: Searching for causative stimuli in the following order
    • Drainage bag and catheter: to check any obstruction (if the patient has an indwelling catheter in situ)
    • Suprapubic palpation: to check bladder distention (if the patient does CIC)
    • Rectal examination: to check fecal impaction
    • Skin ulceration or musculoskeletal disturbance
  • Pharmacological treatment of acute AD:
    • Nifedipine: sublingual nifedipine [Steinberger 1990]
      • alleviating AD:
        • 10-20mg during cystoscopy
        • "bite and swallow" technique to enhance rapid absorption
      • preventing AD: 10mg oral, 30 minutes before cystoscopy
    • Nitrates: sublingual or topical
    • Captopril: sublingual [Esmail 2002]
    • Hydralazine or diazoxide: i.v
    • Parenteral ganglionic or α-adrenergic blockade or with parenteral chlorpromazine.
  • Clinical implications
    • Treatment should be initiated swiftly if AD develops.
    • Early recognition of AD is important.
  • Prophylaxis:

    • Before procedures:
      • Electroejaculation:
        • oral prophylaxis with 20 mg of nifedipine [Steinberger 1990]
        • careful monitoring during procedure
      • Endoscopic procedure in susceptible patients: spinal or general anesthesia
    • Preventing measures:
      • Surgical:
        • Sympathectomy is impractical, as the response is generalized.
        • Afferent sacral rhizotomy: block the afferent genesis of the syndrome.
        • Sacral dorsal root ganglionectomy: block the afferent genesis of the syndrome.
        • Spinal anesthesia: block the afferent genesis of the syndrome.
        • Local anesthetics instilled into the bladder and left there 15 minutes (30 mls Xylocaine 2%) blocks afferent stimuli from the bladder and allows changing suprapubic tubes safely, for example.
      • Medical:
        • Alpha blocker (terazosin 5mg po hs for long-term management) [Chancellor 1994]
        • Chlorpromazine 1 to 2 mg IV for and acute episode: blunts the autonomic response
        • Chlorpromazine 12 to 25 mg IM or PO, 2 to 4 times daily can be used for chronic treatment of very susceptible patients.
      • Structured education:
        • To the patients:
          • Perhaps the most important in prevention
          • Provided during the initial period of rehabilitation
          • Good urinary and bowel care To avoid complications
        • To all healthcare professionals:
          • Should be aware of the potential problems.
          • And able to recognize the symptoms and signs

     

    Key Points of This Section
    • AD symptoms and signs include headache, skin flushing, bradycardia and hypertension; the syndrome can be lethal.
    • Treatment can be directed at the sympathetic response: alpha blocking agents (chlorpromazine, or regitine IV, nitrites, IV, sublingual or topical, oral nifedipine, or at the afferent genesis of the reflex response: bladder, rectum, of other irritative focus, but it must be initiated quickly and effectively.
    • Chronic treatment of the sympathetic response can be directed at the motor side or the afferent side. Oral medication blunts the sympathetic response, and control of bladder pressure and volume or rectal distention eliminates the most common precipitating causes of AD.

    References

    • Bateman AM, Goldish GD. Autonomic dysreflexia in multiple sclerosis. J Spinal Cord Med 2002;25:40–2.
    • Chancellor MB, Erhard MJ, Hirsch IH, Stass WE Jr. Prospective evaluation of terazosin for the treatment of autonomic dysreflexia. J Urol. 1994 Jan;151(1):111-3.
    • Esmail Z, Shalansky KF, Sunderji R, Anton H, Chambers K, Fish W. Evaluation of captopril for the management of hypertension in autonomic dysreflexia: a pilot study. Arch Phys Med Rehabil. 2002 May;83(5):604-8.
    • Finestone HM, Teasell RW. Autonomic dysreflexia after brainstem tumor resection. A case report. Am J Phys Med Rehabil 1993;72:395–7.
    • Furlan JC, Fehlings MG, Halliday W, et al. Autonomic dysreflexia associated with intramedullary astrocytoma of the spinal cord. Lancet Oncol 2003;4:574–5.
    • Kewalramani LS. Autonomic dysreflexia in traumatic myelopathy. Am J Phys Med 1980;59:1–21.
    • Krassioukov AV, Furlan JC, Fehlings MG. Autonomic dysreflexia in acute spinal cord injury: an under-recognized clinical entity. J Neurotrauma 2003;20:707–16.
    • Lindan R, Joiner E, Freehafer AA, et al. Incidence and clinical features of autonomic dysreflexia in patients with spinal cord injury. Paraplegia 1980;18:285–92.
    • Shergill IS, Arya M, Hamid R, et al. The importance of autonomic dysreflexia to the urologist. BJU Int 2004;93:923–6.; Karlsson AK. Autonomic dysreflexia. Spinal Cord 1999;37:383–391.
    • Steinberger RE, Ohl DA, Bennett CJ, McCabe M, Wang SC. Nifedipine pretreatment for autonomic dysreflexia during electroejaculation. Urology. 1990 Sep;36(3):228-31

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