Emergent Treatment of Acute Spinal Cord Injuries: Current Status
Stephen M. Papadopoulos, MD
Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona
In the United States the incidence of acute spinal cord injury is about 10,000 new cases each year. The economic impact of spinal cord injury is estimated to be more than 4 billion dollars each year. Immediate pharmacological treatment of acute spinal cord injury has improved neurological outcomes in experimental animal models and in clinical trials. Experimental models strongly suggest that early decompression of the spinal cord after acute injury is beneficial, but supportive clinical evidence is sparse. Neural decompression after injury is a fundamental tenant of neurosurgical care. However, the effect of immediate surgical decompression of the spinal cord on neurological outcome after spinal cord injury is controversial. Many authors suggest that early treatment in accordance with accepted trauma treatment paradigms may improve neurological recovery. Additional clinical studies of this multifactorial and complex issue are needed.
Key Words: spinal cord injury
The incidence of acute spinal cord injury in the United States is about 10,000 new cases annually, resulting in 720 per million of the population with permanent disability each year.[39,53] The economic impact of spinal cord injury is estimated to be more than 4 billion dollars annually. Laboratory models, anecdotal case reports, and small clinical series suggest that early surgical decompression may improve neurological recovery after acute spinal cord injury.[11,16,18,23,43] However, other clinical series have failed to demonstrate a positive effect on neurological outcome. In fact, some investigators report worsened outcomes after surgery.[4,20,29,37,38,58,59] Thus, many clinicians have developed a pessimistic attitude toward urgent surgical treatments for spinal column realignment and spinal cord decompression. This article reviews the current controversies and status of the surgical treatment of spinal cord injuries.
Immediate decompression of neural tissue is intended to limit secondary injury to the spinal cord after trauma.[12,52,64,65] In 1911 Allen first postulated the importance of secondary injury mechanisms. He found that surgical myelotomy and drainage of traumatic hematomyelia enhanced the recovery of neurological function after experimental spinal cord injury in dogs. Subsequent investigators have proposed roles for spinal cord ischemia, catecholamine release, oxygen free-radical formation, calcium ion entry, and cytokine release among others in the pathophysiology of secondary injury.[15,27,52,55,63,64] These findings have prompted successful pharmacological interventions in human spinal cord injury.[7,8,21]
Animal models of spinal cord injury demonstrate that persistent spinal cord compression may be a reversible source of secondary injury if treated within minutes to hours of the initial insult.[16,23,33,41,43,50,51] Two important factors largely determine the potential for recovery after acute spinal cord injury: the force of the initial compressive injury and the length of time the compression persists.[23,50,51] Although the initial compressive force is determined at the moment of injury, the length of time that compression persists can be altered by early therapeutic intervention, thereby potentially improving a patient’s ultimate neurological recovery.
Recent clinical trials have advanced the pharmacological treatment of acute spinal cord injury and improved neurological outcomes in selected patients.[5-9,21] Other studies have demonstrated the value of intensive hemodynamic monitoring and critical care management in these patients during the acute phase of injury. [31,54,57,63] The role of early surgical intervention in acute spinal cord injury, however, remains controversial.
Anecdotally, immediate spinal cord decompression in patients, which can be accomplished by surgery or by closed reduction of spinal malalignment, has been associated with remarkable neurological recovery despite the presence of a complete motor injury.[11,26,62]
Throughout this century, spinal cord decompression, vertebral column stabilization, or both have been common treatments for acute cervical spinal cord injury. However, a prospective study of the appropriate timing of surgical decompression following spinal cord injury has never been conducted.[48,52] The investigators of the National Acute Spinal Cord Injury Study-2 (NASCIS-2) retrospectively analyzed surgical treatment in their pharmacological protocol patients and concluded that a randomized study on the timing and efficacy of spinal cord decompressive surgery is necessary.
“Early” surgical intervention in acute spinal cord injury, defined between 48 hours and 2 weeks after injury, has seldom been associated with improved recovery, and in some cases neurological recovery has worsened.[2,13,14,20,24,25,28-30,37,40,56] Some authors have suggested that spinal cord decompression in the clinical setting may have been too late to avert the secondary injury of neural tissue.[16,23,43] Edema of neural tissue developing between 24 hours and 5 to 7 days after injury may predispose patients undergoing operations at that time to neurological deterioration. Marshall and colleagues37 reported that surgery within 5 days of injury worsened neurological outcomes. A recent controlled study of 64 patients who underwent surgery within 72 hours of injury (mean, 43 hours) found no benefit associated with early surgery. It may be possible to treat secondary injury only within a short time interval, such as used with methylprednisolone therapy.[6-9] Many authors’ results suggest that a similar time interval, measured in hours rather than days, also applies to spinal cord decompression for acute spinal cord injury.
Magnetic resonance (MR) imaging is now readily available in the setting of acute trauma, and its availability has improved anatomical delineation of injuries to the spinal column and to the spinal cord itself.[10,32,34,46] Emergency MR imaging after spinal cord injury provides accurate prognostic information about neurological function and helps in the diagnosis and treatment of persistent spinal cord compression after vertebral realignment. The findings of anterior compressive lesions on MR imaging in most patients with an acute spinal cord injury have increased the use of anterior surgical approaches to treat these injuries.[3,35,48,57] Cervical laminectomy alone, which was commonly used in this setting in the past, is now known to increase the risk of spinal column destabilization and neurological deterioration in patients with anterior compressive lesions.
The use of MR imaging-directed surgical approaches may contribute to improved neurological outcomes. In several contemporary studies using MR imaging in the management of acute spinal cord injury, anterior or combined anterior and posterior surgical approaches were used to decompress the spinal cord in a large proportion of the patients who required surgery.[17,35,42,57] Emergency MR imaging, obtained within hours of spinal cord injury, also helps diagnose persistent spinal cord compression after vertebral column realignment and helps determine the prognosis for neurological recovery. Information obtained from MR imaging is particularly helpful in the diagnosis of a traumatic herniated nucleus pulposus, epidural hematomas, and anterior and posterior ligamentous injuries. Interestingly, the appearance of intraparenchymal hemorrhage in these patients may not negate the possibility of meaningful neurological recovery.
Several authors have advocated MR imaging before closed cervical traction is implemented in patients with bilateral facet dislocations to identify patients with herniated disk material within the spinal canal who might suffer neurological deterioration during reduction.[17,36,44] This approach is controversial and must be balanced against the “waiting time” to obtain an MR imaging study.[22,26,48] In a recent review of 80 consecutive patients with acute cervical trauma and subluxation who underwent successful closed cervical reduction, the neurological condition of only one patient (1.2%) deteriorated. The condition of none of the 15 patients with bilateral facet dislocations deteriorated. Larger numbers of patients must be studied to resolve this issue. However, I agree with the currently recommended practice of obtaining initial MR imaging if immediately available. Otherwise, emergency closed cervical reduction of bilateral locked facets should be performed without delay.
The expense of initial hospitalization is the most significant contributor to the total cost of care for patients with an acute spinal cord injury. Costs are primarily related to the length of the initial hospital stay. Papadopoulos et al. found that patients undergoing emergency decompression and spinal column stabilization for a spinal cord injury needed significantly fewer days of ventilatory support and spent significantly fewer days in the intensive care unit (ICU) than did reference patients. The reduced length of ventilator dependence in these patients most likely contributed to their shortened stays in the ICU.[42,53] Patients who underwent emergency decompression and stabilization also spent fewer total days in the hospital (intensive care, general care, rehabilitation, and combined care units) than reference patients. Reduced ventilator dependence and length of stay in the ICU may limit secondary deconditioning and lead to a more rapid and successful rehabilitation. Consistent with these findings, other investigators have reported that early spinal column stabilization and patient mobilization reduced the incidence of medical complications, including pneumonia, deep venous thrombosis, decubitus ulceration, and urinary tract infection in patients with an acute spinal cord injury.[48,54,61]
The lifetime cost of spinal cord injury-related care and lost productivity is closely related to the severity of injury and a patient’s ultimate degree of neurological recovery.[53,60] The potential savings implicit in the improved long-term neurological outcome is difficult to calculate accurately but would likely be substantial.
Based on recent advances in the clinical management of acute spinal cord injury, several authors have suggested that urgent spinal cord decompression after injury, guided by acute radiological imaging data, may improve neurological outcomes.[19,48,54] In a retrospective analysis of patients enrolled in the National Acute Spinal Cord Injury Study, Wilberger and colleagues did not find that early surgery was associated with a beneficial effect. In a prospective clinical trial, Papadopoulos and coworkers demonstrated that emergency spinal cord decompression and early spinal column stabilization for the treatment of acute cervical spinal cord injury may improve neurological outcomes and reduce the cost of the initial management of these patients. Nevertheless, no contemporary prospective, randomized clinical studies have unequivocally addressed the role of immediate spinal cord decompression and spinal column stabilization after an acute spinal cord injury.
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