Autonomic function following cervical spinal cord injury☆
Introduction
In addition to devastating paralysis, spinal cord injury (SCI) also results in significant dysfunctions of the autonomic nervous system (ANS) (Krassioukov and Claydon, 2006). While the injury itself generally affects only a small area of the spinal cord tissue, the effect of this local disruption can commonly be seen in all spinal autonomic functions—both sympathetic and parasympathetic. There is also a very strong correlation between the level of SCI and the severity of autonomic dysfunctions. For example, individuals with cervical SCI face the daily challenge of managing an unstable blood pressure, which frequently results in persistent resting hypotension and/or episodes of uncontrolled hypertension, known as autonomic dysreflexia (Krassioukov and Claydon, 2006). These cardiovascular abnormalities have been well documented in human studies, as well as in animal models (Krassioukov et al., 1999, Mathias and Frankel, 2002, Claydon et al., 2006a, Claydon et al., 2006b, Inskip et al., 2009). Furthermore, cervical injury disrupts, not only respiratory motor output to the diaphragm, but coordinated autonomic control of the broncho-pulmonary functions as well, resulting in abnormal bronchial secretion, airway hypersensitivity, and other respiratory issues (Fein et al., 1998, Singas et al., 1999, Grimm et al., 2000). Both of these conditions are absent in individuals with low thoracic or conal injuries. The recognition and management of these cardiovascular and respiratory dysfunctions following SCI represent challenging clinical issues. Moreover, cardiovascular and respiratory disorders in the acute and chronic stages of SCI are among the most common causes of death in individuals with SCI (DeVivo et al., 1999, Garshick et al., 2005). Until recently, the majority of basic science and clinical investigations were focused on finding a cure for paralysis and reestablishing motor function. Unfortunately, we are only starting to understand the complexity of autonomic dysfunctions associated with SCI and the impact such dysfunctions have on those individuals (Krassioukov et al., 2007). This chapter will predominantly focus on the clinical issues associated with abnormal autonomic control of cardiovascular and broncho-pulmonary functions following SCI.
Section snippets
General organization of the autonomic nervous system
There are two components within the autonomic nervous system (ANS): sympathetic and parasympathetic (Krassioukov and Weaver, 1996a, Krassioukov and Weaver, 1996b). Most of the visceral organs are innervated by both components of the ANS, including the heart and broncho-pulmonary tree (Krassioukov and Weaver, 1996a, Krassioukov and Weaver, 1996b, Lefkowitz et al., 2007). However, with the exception of the cavernous tissue of the penis and clitoris (which have parasympathetic innervations) the
Acute period following SCI
Initially, following the injury, there is a marked reduction or abolition of sensory, motor, and reflex function of the spinal cord below the level of injury, known as spinal shock (Ditunno et al., 2004). This condition is also commonly accompanied by severe cardiovascular dysfunctions, especially with injury at the cervical level. Individuals with such injuries typically present with severe hypotension and persistent bradycardia—common components of the phenomenon known as neurogenic shock (
Effect of spinal cord injury on respiratory functions
Similar to their impact on cardiovascular functions, the level and completeness of injury can significantly alter the possible outcomes in respiratory functions following SCI. The coordination between somatic control of the respiratory muscles and autonomic control of the broncho-pulmonary tree is crucial for normal respiration and blood oxygenation. Loss of diaphragmatic voluntary inspiration is the most prominent feature of high cervical SCI. Specifically, the preservation of the integrity of
Conclusion
In addition to motor and sensory deficits, individuals with SCI face life-long abnormalities in blood pressure control and frequently present with various degrees of respiratory dysfunctions (Spungen et al., 1997, Mathias and Frankel, 2002, Cardenas et al., 2004, Claydon et al., 2006a, Claydon et al., 2006b, Chiodo et al., 2008). The severity of these dysfunctions depends on the level and completeness of injury of the spinal cord. Clinical evidence suggests that individuals with cervical SCI
References (90)
- et al.
Spinal shock
Mayo Clin. Proc.
(1996) - et al.
Etiology and incidence of rehospitalization after traumatic spinal cord injury: a multicenter analysis
Arch. Phys. Med. Rehabil.
(2004) - et al.
Catecholamine enzymes and neuropeptides are expressed in fibres and somata in the intermediate grey matter in chronic spinal rats
Neuroscience
(1997) - et al.
Co-localization of substance P and dopamine β-hydroxylase with growth associated protein-43 is lost caudal to a spinal cord transection
Neuroscience
(1999) - et al.
Autonomic hyperreflexia in spinal cord injury patient during percutaneous nephrolithotomy for renal stone: a case report
J. Urol.
(1991) - et al.
Cardiovascular responses and postexercise hypotension after arm cycling exercise in subjects with spinal cord injury
Arch. Phys. Med. Rehabil.
(2006) - et al.
Recent trends in mortality and causes of death among persons with spinal cord injury
Arch. Phys. Med. Rehabil.
(1999) - et al.
Bronchial hyperresponsiveness after cervical spinal-cord injury
Chest
(1994) - et al.
Airway hyperreactivity in subjects with tetraplegia is associated with reduced baseline airway caliber
Chest
(2000) - et al.
Silent autonomic dysreflexia during a routine bowel program in persons with traumatic spinal cord injury: a preliminary study
Arch. Phys. Med. Rehabil.
(2002)
The clinical problems in cardiovascular control following spinal cord injury: an overview
Prog. Brain Res.
Effect of graded spinal cord compression on cardiovascular neurons in the rostro-ventro-lateral medulla
Neuroscience
A systematic review of the management of autonomic dysreflexia after spinal cord injury
Arch. Phys. Med. Rehabil.
Complications of autonomic dysreflexia
J. Urol.
Cardiovascular abnormalities accompanying acute spinal cord injury in humans: incidence, time course and severity
J. Am. Coll. Cardiol.
Autonomic hyperreflexia: a mortal danger for spinal cord-damaged women in labor
Am. J. Obstet. Gynecol.
Intracerebral hemorrhage secondary to autonomic dysreflexia in a young person with incomplete C8 tetraplegia: a case report
Arch. Phys. Med. Rehabil.
Assessment of airway caliber and bronchodilator responsiveness in subjects with spinal cord injury
Chest
Peripheral and central pathways regulating the kidney: a study using pseudorabies virus
Brain Res.
Cardiovascular consequences of loss of supraspinal control of the sympathetic nervous system following spinal cord injuries
Arch. Phys. Med. Rehabil.
Acute management of autonomic dysreflexia: adults with spinal cord injury presenting to health-care facilities. Consortium for spinal cord
J. Spinal Cord Med.
International standards to document remaining autonomic function after spinal cord injury
Spinal Cord
Neural control of human airways in health and disease
Am. Rev. Respir. Dis.
Rehabilitation medicine. 1. Autonomic dysreflexia
CMAJ
Enhanced neurally evoked responses and inhibition of norepinephrine reuptake in rat mesenteric arteries after spinal transection
Am. J. Physiol.: Heart Circ. Physiol.
Spinal cord lamina V and lamina VII interneuronal projections to sympathetic preganglionic neurons
J. Comp. Neurol.
Medullary basal sympathetic tone
Annu. Rev. Physiol.
Reflex regulation of airway smooth muscle tone
J. Appl. Physiol.
Predictors of ventilator weaning in individuals with high cervical spinal cord injury
J. Spinal Cord Med.
Orthostatatic hypotention and autonomic pathways following spinal cord injury
J. Neurotrauma
Cardiovascular responses to vibrostimulation for sperm retrieval in men with spinal cord injury
J. Spinal Cord Med.
Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology
Spinal Cord
Effects of beta-adrenergic-receptor agonists and antagonists in diabetics with symptoms of postural hypotension—a double-blind. Placebo-Controlled Study
ANGIA
Autonomic hyperreflexia associated with recurrent cardiac arrest: case report
Spinal Cord
Assessment of autonomic dysreflexia in patients with spinal cord injury
J. Neurol. Neurosurg. Psychiatry
Spinal shock revisited: a four-phase model
Spinal Cord
Malignant autonomic dysreflexia in spinal cord injured men
Spinal Cord
Fatal cerebral hemorrhage due to autonomic dysreflexia in a tetraplegic patient: case report and review
Paraplegia
The effects of ipratropium bromide on histamine-induced bronchoconstriction in subjects with cervical spinal cord injury
J. Asthma
Postural hypotension and abnormalities of salt and water metabolism in myelopathy patients
Spinal Cord
Descending vasomotor pathways in humans: correlation between axonal preservation and cardiovascular dysfunction after spinal cord injury
J. Neurotrauma
A prospective assessment of mortality in chronic spinal cord injury
Spinal Cord
Autonomic dysreflexia during urodynamics
Spinal Cord
Cardiovascular changes following spinal cord injury
Top. Spinal Cord Inj. Rehabil.
Autoregulation of cerebral blood flow in patients with orthostatic hypotension after spinal cord injury
Paraplegia
Cited by (222)
Mechanistic involvement of noradrenergic neuronal neurotransmitter release in cutaneous vasoconstriction during autonomic dysreflexia in persons with spinal cord injury
2024, Autonomic Neuroscience: Basic and ClinicalExercise Training Does Not Attenuate Cardiac Atrophy or Loss of Function in Individuals With Acute Spinal Cord Injury: A Pilot Study
2023, Archives of Physical Medicine and RehabilitationAutonomic dysreflexia in urological practice: pathophysiology, prevention and treatment considerations
2024, World Journal of Urology
- ☆
This paper is part of a special issue entitled ‘Spinal cord injury—Neuroplasticity and recovery of respiratory function’, guest-edited by Gary C. Sieck and Carlos B. Mantilla.