Proposal of a Management Algorithm to Predict the Need for Expansion Duraplasty in American Spinal Injury Association Impairment Scale Grades A-C Traumatic Cervical Spinal Cord Injury Patients

Abstract

Expansion duraplasty to reopen effaced subarachnoid space and improve spinal cord perfusion, autoregulation, and spinal pressure reactivity index (sPRX) has been advocated in patients with traumatic cervical spinal cord injury (tCSCI). We designed this study to identify candidates for expansion duraplasty, based on the absence of cerebrospinal fluid (CSF) interface around the spinal cord on magnetic resonance imaging (MRI), in the setting of otherwise adequate bony decompression. Over a 61-month period, 104 consecutive American Spinal Injury Association Impairment Scale (AIS) grades A-C patients with tCSCI had post-operative MRI to assess the adequacy of surgical decompression. Their mean age was 53.4 years, and 89% were male. Sixty-one patients had falls, 31 motor vehicle collisions, 11 sport injuries, and one an assault. The AIS grade was A in 56, B in 18, and C in 30 patients. Fifty-four patients had fracture dislocations; there was no evidence of skeletal injury in 50 patients. Mean intramedullary lesion length (IMLL) was 46.9 (standard deviation = 19.4) mm. Median time from injury to decompression was 17 h (interquartile range 15.2 h). After surgery, 94 patients had adequate decompression as judged by the presence of CSF anterior and posterior to the spinal cord, whereas 10 patients had effacement of the subarachnoid space at the injury epicenter. In two patients whose decompression was not definitive and post-operative MRI indicated inadequate decompression, expansion duraplasty was performed. Candidates for expansion duraplasty (i.e., those with inadequate decompression) were significantly younger (p < 0.0001), were AIS grade A (p < 0.0016), had either sport injuries (six patients) or motor vehicle collisions (three patients) (p < 0.0001), had fracture dislocation (p = 0.00016), and had longer IMLL (p = 0.0097). In regression models, patients with sport injuries and inadequate decompression were suitable candidates for expansion duraplasty (p = 0.03). Further, 9.6% of patients failed bony decompression alone and either did (2) or would have (8) benefited from expansion duraplasty.

Keywords: decompression; duraplasty; neuroprotection; spinal cord injury; surgery.

FIG. 1.

Graph indicating the relationship between mechanism of injury and the percentage of patients who could benefit from duraplasty for complete spinal cord decompression. MVC, motor vehicle collision.

FIG. 2.

Post-operative midsagittal magnetic resonance imaging (MRI) views from 10 randomly selected patients with adequate decompression plates (A–J). Adequate decompression was defined as presence of cerebrospinal fluid (CSF) interface in front, behind, or in front/behind of the spinal cord. In panels A, C, and F, the CSF interface is partially missing behind the spinal cord, which might be because of the effect of gravity while the patient is in the supine position in the MRI gantry.

FIG. 3.

Post-operative midsagittal magnetic resonance imaging views from 10 patients with inadequate decompression despite anterior cervical corpectomy and fusion (ACCF) and laminectomy (plates A, B, D, E, F, J), anterior cervical discectomy and fusion, and laminectomy (plate C), and standalone laminectomy with posterior spinal fusion (plates G, H, I). The cerebrospinal fluid (CSF) is not visible either dorsal or ventral to the spinal cord indicating excessive swelling. Although intraspinal pressure was not unknown, in patients B and C, expansion duraplasty was performed to generate a CSF interface between the spinal cord and dura.

FIG. 4.

Proposed expansion duraplasty aimed at reducing intraspinal pressure (ISP) and improving spinal cord perfusion pressure (SCPP) and spinal pressure reactivity index and autoregulation Plates A–D (after Saadoun with permission Neurotherapeutics 17:511-521, 2020³⁸). CSF, cerebrospinal fluid; tSCI, traumatic spinal cord injury.

FIG. 5.

Midsagittal post-operative magnetic resonance imaging view of a 58-year-old man with motor vehicle collision and an American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade C (ASIA motor score 10) spinal cord injury indicating hematomyelia, cord swelling (intramedullary lesion length 62.5 mm), and complete decompression of the spinal cord as evidenced from the cerebrospinal fluid (CSF) interface in front and in the back of the spinal cord (plate A). The composite plates on the right side are real-time intraoperative ultrasonography with presence of CSF around (plates B, C, and D), in front, and the back of the spinal cord (plate E).

FIG. 6.

Midsagittal computed tomography and magnetic resonance imaging (MRI) views (plates A and B) from a 20-year-old male patient with C4/5 unilateral locked facets and quadriplegia during a friendly game of wrestling. Plate A indicates translation rotation injury between C4 and C5 (AOSpine injury type C) vertebral bodies 6 h after trauma. Nine hours after traction reduction, the MRI indicated lack of cerebrospinal fluid (CSF) interface in front and in the back of the spinal cord from C2–C6 and an intramedullary lesion length of 73.1 mm. (plate B). After anterior cervical discectomy and fusion, MRI (plate D) indicated continued absence of CSF in front and in the back of the spinal cord. The patient had a second stage surgery that was laminectomy. Real-time intraoperative ultrasonography after laminectomy revealed spinal cord swelling with a thin interface in front of the spinal cord; however, the surgeon was not convinced expansive duraplasty was necessary (plates E and F). Post-operative MRI (plate G) revealed absence of CSF around the spinal cord at C4/5 skeletal segments. Although intraspinal pressure monitoring was not available at the time, the patient was re-explored for expansion duraplasty (plates H, I, and J), which re-established CSF interface around the spinal cord.