From the Guidelines
Autonomic dysfunction following spinal cord injury (SCI) can lead to significant morbidity and mortality, and maintaining a mean arterial pressure (MAP) > 70 mmHg is crucial in the acute phase to improve neurological outcomes. The effects of autonomic dysfunction following SCI are multifaceted, affecting various bodily systems and requiring comprehensive management.
Key Effects of Autonomic Dysfunction
- Autonomic dysreflexia: a life-threatening condition characterized by sudden elevations in blood pressure, often triggered by noxious stimuli below the level of injury 1.
- Orthostatic hypotension: managed with abdominal binders, compression stockings, and medications like midodrine or fludrocortisone.
- Temperature dysregulation: patients lose the ability to sweat and vasodilate below the injury level, requiring environmental modifications to prevent hyperthermia or hypothermia.
- Sexual dysfunction: may require specialized interventions.
Management and Prevention
- Immediate identification and removal of the triggering stimulus is crucial in managing autonomic dysreflexia, often involving bladder distension, bowel impaction, pressure sores, or tight clothing 1.
- Preventive measures include regular bladder and bowel programs, skin care protocols, and proper positioning.
- Maintaining a MAP > 70 mmHg in the acute phase is associated with better neurological status at 6 months, as shown in a study evaluating the neurological prognosis in 92 patients with traumatic spinal cord injury 1.
Pathophysiology and Clinical Implications
The pathophysiology of autonomic dysfunction involves disruption of descending inhibitory pathways from higher centers to the sympathetic preganglionic neurons, resulting in uncontrolled sympathetic outflow below the level of injury when triggered, while parasympathetic function remains intact.
- A study analyzing continuous blood pressure collection in 74 patients with spinal cord injury highlighted the difficulty in achieving target MAP levels, emphasizing the need for continuous monitoring with an arterial catheter 1.
- The American Association of Neurological Surgeons/Congress of Neurological Surgeons recommends targeting supra-physiological objectives of mean blood pressure (MAP > 85 mmHg) within the first 5 to 7 days, although the evidence level for this recommendation is limited 1.
From the Research
Effects of Autonomic Dysfunction Following Spinal Cord Injury (SCI)
The effects of autonomic dysfunction following spinal cord injury (SCI) are numerous and can be life-threatening. Some of the key effects include:
- Compromised cardiovascular function, including disordered hemodynamics and episodic hypertension associated with autonomic dysreflexia 2, 3
- Respiratory problems, including impaired respiratory function and risk of pulmonary edema 4, 5
- Urinary and gastrointestinal dysfunction, including bladder and bowel control issues, and renal and sexual function problems 2, 5
- Thermoregulatory dysfunction, including risk of hyperthermia or hypothermia 6, 5
- Sexual dysfunction, including impaired sexual function and fertility 2, 5
Autonomic Dysreflexia
Autonomic dysreflexia is a potentially life-threatening condition that can occur in individuals with SCI, particularly those with injuries at or above T6. It is characterized by a sudden increase in blood pressure induced by afferent sensory stimulation, and can lead to serious complications such as cerebral or retinal hemorrhage, seizures, heart failure, or pulmonary edema 3.
Management and Prevention
Management and prevention of autonomic dysfunction following SCI are crucial to prevent secondary complications. This includes recognition of the clinical presentation of symptoms and signs, as well as implementation of preventive and treatment measures such as monitoring of blood pressure, management of bladder and bowel function, and prevention of pressure sores 6, 5. However, more research is needed to fully understand the effects of autonomic dysfunction following SCI and to develop effective management and prevention strategies 4, 3.
Cardiovascular and Cerebrovascular Complications
Cardiovascular and cerebrovascular complications are common in individuals with SCI, and can be life-threatening. These complications include orthostatic hypotension, autonomic dysreflexia, and impaired cerebral blood flow regulation 2, 4, 3. Effective management of these complications is essential to prevent secondary injuries and improve quality of life for individuals with SCI.
Gastrointestinal and Urinary Complications
Gastrointestinal and urinary complications are also common in individuals with SCI, and can have a significant impact on quality of life. These complications include gastrointestinal motility disorders, neurogenic bowel dysfunction, and urinary retention or incontinence 2, 5. Management of these complications requires a comprehensive approach that includes medical and surgical interventions, as well as lifestyle modifications.