Post-traumatic syringomyelia (PTS) is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord after a trauma. PTS was rarely reported, and the significance of the past history of spinal trauma was overlooked. Symptomatic PTS has a reported prevalence of 4%,4) but the prevalence of asymptomatic PTS among patients with spinal cord injuries (SCIs) is estimated at approximately 28%.9) PTS generally develops within 5 years after the initial spinal injury, but ranges from 6 months to 25 years.2)

The pathophysiology of PTS is not completely understood. It has been proven that post-traumatic arachnoiditis can cause cavitation in the spinal cord and may also cause syringomyelia. The delayed development of syringomyelia after a severe single spinal trauma that results in contusion of the spinal cord without the complication of arachnoiditis is well-known issue. PTS has been treated by shunting procedure or decompression, and outcomes were poor. The purpose of this study was to review the clinical manifestations and surgical treatment results of PTS.

Between 1992 and 2012, nine patients with symptomatic PTS underwent operations. All the patients had evident and progressive neurological symptoms. We excluded patients with congenital anomalies or tumors related to syringomyelia from this analysis. In all nine patients, the syringomyelia was caused by spinal trauma. These patients were examined with preoperative magnetic resonance images (MRI). MRI was used to analyze the injury site, craniocaudal extension of the syrinx, the degree of spinal stenosis, and the quality of the subarachnoid spaces around the syrinx. By the late 1990's, patients underwent the shunting procedures. Arachnoidolysis and duraplasty were performed after the late 1990's. The mean follow-up period was 9.3 years (range, 2-17 years). The major presenting symptoms or signs were assessed in terms of their improvement, stabilization and deterioration.

PTS is an uncommon but increasingly recognized cause of morbidity following SCI. The development of a syrinx takes months to years after the initial injury. The most frequent presenting symptoms of PTS are pain, numbness or increased weakness, and the reported interval between spinal trauma and the presenting neurological symptoms ranges from 2 months to 36 years.13) In this study, most common symptom is the numbness and weakness and the mean interval between the initial injury and the onset of new symptoms was 21.9 years.

Previous reports showed that syrinx extension may be due to secondary distention of the epidural veins or pressure changes leading to cerebrospinal fluid (CSF) movement during a Valsalva maneuver.8) Furtheromre, PTS most commonly extends above from the injury site; though, less frequently, it may also have an inferior component.10) In this study, syringes usually extended above or above and below from spinal injury sites.

Surgery is performed on patients with syrinx that become symptomatic. Syringo-peritoneal shunts and syringo-pleural shunts are commonly used in patients with syringomyelia associated with spinal arachnoiditis because of adhesion in the spinal subarachnoid space.6) The placement of all types of shunts may be followed by significant morbidity requiring additional surgical procedures.1,3,5,7,11,12) Problems specific to the shunt operation include dislodged, blocked, and infected drains. Shunting procedures were widely used with encouraging early results, although long-term results has been questioned recently. They are not directed at the etiology of syringomyelia. A higher rate of shunt failure (approximately 50%) and poor long-term outcomes were reported from various shunting procedures.1,12) In this study, we performed shunting procedures in five patients; two patients stabilized and three deteriorated. Thus, our study outcome was similar to that of previous reports. Mechanical shunt failures occurred in two of the five patients. Shunt obstruction and spinal cord tethering may account for the gradual neurological deterioration.

The occurrence of pressure differences between the zone above the arachnoiditis and that below seems to be important. Permitting free communication among the CSF pathways so that there are no pressure differentials across the walls of the cord is exxential.14) Decompressive procedures may have beneficial effects unless the patient shows longitudinally extensive arachnoiditis. The first line of treatment should focus on restoring the normal CSF flow at the trauma level and untethering the cord and duroaplasty.12)

In this study, the post-traumatic tethering, which may lead to a progressive myelopathy, could not be released well. Of the 4 patients who underwent arachnoidolysis and duraplasty, two patients showed no neurological changes, one patient improved, and one patient deteriorated. Arachnoidolysis and duraplasty had no better long-term results than shunt-ing operations.

PTS is a rare complication. In patients with a previous spinal injury and newly acquired neurological deficits, we should be aware of the possibility of PTS. Although we performed surgical interventions, patients with PTS demonstrated unfavorable long-term outcomes.