The purpose of this review was to describe the relevant factors that influence neurological outcomes in patients who sustain traumatic conus medullaris injuries (CMIs) and cauda equina injuries (CEIs). Despite the propensity for spinal trauma to affect the thoracolumbar spine, few studies have adequately characterized the outcomes of CMIs and CEIs. Typically the level of neural axis injury is inferred from the spinal level of injury or the presenting neurological picture because no study from the spinal literature has specifically evaluated the location of the conus medullaris with respect to the level of greatest canal compromise. Furthermore, the conus medullaris is known to have a small but important variable location based on the spinal level. Patients with a CMI will typically present with variable lowerextremity weakness, absent lower-limb reflexes, and saddle anesthesia. The development of a mixed upper motor neuron and lower motor neuron syndrome may occur in patients with CMIs, whereas a CEI is a pure lower motor neuron injury. Many treatment options exist and should be individualized. Posterior decompression and stabilization offers at least equivalent neurological outcomes as nonoperative or anterior approaches and has the additional benefits of surgeon familiarity, shorter hospital stays, earlier rehabilitation, and ease of nursing care. Overall, CEIs and CMIs have similar outcomes, which include ambulatory motor function and a variable persistence of bowel, bladder, and potentially sexual dysfunctions.
Stephen P. Kingwell, Armin Curt and Marcel F. Dvorak
Sukhvinder Kalsi-Ryan, Armin Curt, Mary C. Verrier and Michael G. Fehlings
Primary outcome measures for the upper limb in trials concerning human spinal cord injury (SCI) need to distinguish between functional and neurological changes and require satisfying psychometric properties for clinical application.
The Graded Redefined Assessment of Strength, Sensibility and Prehension (GRASSP) was developed by the International GRASSP Research and Design Team as a clinical outcome measure specific to the upper limbs for individuals with complete and incomplete tetraplegia (that is, paralysis or paresis). It can be administered across the continuum of recovery after acute cervical SCI. An international multicenter study (involving centers in North America and Europe) was conducted to apply the measure internationally and examine its applicability.
The GRASSP is a multimodal test comprising 5 subtests for each upper limb: dorsal sensation, palmar sensation (tested with Semmes-Weinstein monofilaments), strength (tested with motor grading of 10 muscles), and prehension (distinguishes scores for qualitative and quantitative grasping). Thus, administration of the GRASSP results in 5 numerical scores that provide a comprehensive profile of upper-limb function. The established interrater and test-retest reliability for all subtests within the GRASSP range from 0.84 to 0.96 and from 0.86 to 0.98, respectively. The GRASSP is approximately 50% more sensitive (construct validity) than the International Standards of Neurological Classification of SCI (ISNCSCI) in defining sensory and motor integrity of the upper limb. The subtests show concurrence with the Spinal Cord Independence Measure (SCIM), SCIM self-care subscales, and Capabilities of Upper Extremity Questionnaire (CUE) (the strongest concurrence to impairment is with self-perception of function [CUE], 0.57–0.83, p < 0.0001).
The GRASSP was found to demonstrate reliability, construct validity, and concurrent validity for use as a standardized upper-limb impairment measure for individuals with complete or incomplete tetraplegia. Responsiveness (follow-up from onset to 1 year postinjury) is currently being tested in international studies (in North America and Europe). The GRASSP can be administered early after injury, thus making it a tool that can be administered in acute care (in the ICU), rehabilitation, and outpatient clinics.
Brian K. Kwon, Armin Curt, Lise M. Belanger, Arlene Bernardo, Donna Chan, John A. Markez, Stephen Gorelik, Gerard P. Slobogean, Hamed Umedaly, Mitch Giffin, Michael A. Nikolakis, John Street, Michael C. Boyd, Scott Paquette, Charles G. Fisher and Marcel F. Dvorak
Ischemia is an important factor in the pathophysiology of secondary damage after traumatic spinal cord injury (SCI) and, in the setting of thoracoabdominal aortic aneurysm repair, can be the primary cause of paralysis. Lowering the intrathecal pressure (ITP) by draining CSF is routinely done in thoracoabdominal aortic aneurysm surgery but has not been evaluated in the setting of acute traumatic SCI. Additionally, while much attention is directed toward maintaining an adequate mean arterial blood pressure (MABP) in the acute postinjury phase, little is known about what is happening to the ITP during this period when spinal cord perfusion pressure (MABP − ITP) is important. The objectives of this study were to: 1) evaluate the safety and feasibility of draining CSF to lower ITP after acute traumatic SCI; 2) evaluate changes in ITP before and after surgical decompression; and 3) measure neurological recovery in relation to the drainage of CSF.
Twenty-two patients seen within 48 hours of injury were prospectively randomized to a drainage or no-drainage treatment group. In all cases a lumbar intrathecal catheter was inserted for 72 hours. Acute complications of headache/nausea/vomiting, meningitis, or neurological deterioration were carefully monitored. Acute Spinal Cord Injury motor scores were documented at baseline and at 6 months postinjury.
On insertion of the catheter, mean ITP was 13.8 ± 1.3 mm Hg (± SD), and it increased to a mean peak of 21.7 ± 1.5 mm Hg intraoperatively. The difference between the starting ITP on catheter insertion and the observed peak intrathecal pressure after decompression was, on average, an increase of 7.9 ± 1.6 mm Hg (p < 0.0001, paired t-test). During the postoperative period, the peak recorded ITP in the patients randomized to the no-drainage group was 30.6 ± 2.3 mm Hg, which was significantly higher than the peak intraoperative ITP (p = 0.0098). During the same period, the peak recorded ITP in patients randomized to receive drainage was 28.1 ± 2.8 mm Hg, which was not statistically higher than the peak intraoperative ITP (p = 0.15).
The insertion of lumbar intrathecal catheters and the drainage of CSF were not associated with significant adverse events, although the cohort was small and only a limited amount of CSF was drained. Intraoperative decompression of the spinal cord results in an increase in the ITP measured caudal to the injury site. Increases in intrathecal pressure are additionally observed in the postoperative period. These increases in intrathecal pressure result in reduced spinal cord perfusion that will otherwise go undetected when measuring only the MABP. Characteristic changes in the observed intrathecal pressure waveform occur after surgical decompression, reflecting the restoration of CSF flow across the SCI site. As such, the waveform pattern may be used intraoperatively to determine if adequate decompression of the thecal sac has been accomplished.