Syrinx Decompression Research Articles

Under pressure: Syringo-subarachnoid shunting and syrinx cyst videoscopy

BackgroundSyringomyelia is a well-known spinal cord pathology characterized by an intramedullary cyst that is often chronic and can be progressive. The earliest techniques of syrinx decompression began with simple aspiration after laminectomy and predated anatomic imaging. This was followed by early attempts at keeping communication open between the syrinx and the subarachnoid space using various materials as conduits, essentially creating the first attempts at syringo-subarachnoid shunting (SSS). Even in the modern era of high-quality anatomic imaging with MRI and use of modern materials as implants, novel ways to maintain communication between a syrinx cavity and the subarachnoid space continue to be reported. MethodsA total of 212 patients with imaging-proven syringomyelia presented to our center between 2014 and 2019 and were retrospectively reviewed. The majority of these patients (197) had an identifiable primary cause and surgical treatment was directed at the underlying condition. A total of 18 patients had a T-tube style SSS placed at our center using a K-tube shunt. The mean follow-up was 31.5 months, mean age was 38 years (2–59). The European Myelopathy Score (EMS) and Chicago Chiari Outcome Scale (CCOS) were used to categorize outcomes and progress in these 18 patients. Also we report clinical case to demonstrate technique of K-tube use for syringo-subarachnoid shunting and potential abilities of inner syrinx cyst videoscopy for treatment of syringomyelia in 2-year-old patient with multiple congenital vertebral and spinal cord abnormality. ResultsAmong 16 patients available for follow-up 4 patients (25%) had neurological improvement, 12 patients (75%) remained clinically stable, and no patient had a neurological deterioration based on EMS. Using the CCOS 8 patients (50%) improved, 7 patients (44%) remained stable, and 1 patient (6%) worsened during in the follow-up period. Complications occurred in six patients (33%). Two patients had gait ataxia. Two patients developed postoperative meningitis treated successfully with antibiotics leaving the shunt in place. One patient had a CSF leak successfully treated with a lumbar drain. One patient developed a new pain syndrome. There was no mortality, shunt migration/malposition or reoperation. ConclusionsSyringo-subarachnoid shunting is a well-known and well-described procedure used as “second-line” treatment of syringomyelia worldwide. Our results are consistent with others and make this another surgical option if treatment of a primary source fails or no primary source of the syrinx is found. Our series of 18 patients using a T-tube style SSS adds another good option to those already in use. Recurrence or deterioration following syringomyelia shunting remains a problem and further refinement of technique remains an ongoing process. Syrinx inner videoscopy seems to be safe procedure with possible application to simplify the anatomy of cyst and liquid flow relief.

Syringosubarachnoid shunt: insertion technique

Background Syringomyelia is a rare disorder but its impact on patients’ quality of life can be devastating. The exact pathophysiology remains unknown; the syrinx can either be idiopathic or associated with conditions such as Chiari malformation, scoliosis, malignancy, infection and trauma. Several techniques have been described to decompress syringomyelia with distal drainage to the subarachnoid space, pleura or peritoneum. Method We present a modification of the syringosubarachnoid shunt insertion technique with minimal myelotomy and the use of a T shaped shunt which does not require suturing to the pia matter to prevent shunt migration. Conclusion This technique for syringosubarachnoid shunt insertion is likely to prevent shunt migration and scarring whilst minimizing suturing and optimising syrinx decompression.

Closing the dura: dural hitching versus surgicel and tisseel overlay graft in craniocervicaldecompression for Chiari 1 malformation

Background: This study compares dural hitching to surgicel and tisseel overlay graft following craniocervical decompression and C1 laminectomy with simple durotomy for Chiari I malformation. Outcome measures were syrinx decompression, headache resolution and complication rates.Methods: A retrospective analysis of case notes was conducted. Patients who had undergone craniocervical decompression (CCD) were grouped by method of dural closure. Outcomes compared were rates of syrinx decompression, headache resolution, and post-operative complications. Statistical analysis was conducted using SPSS v20.Results: We identified 32 adult patients for inclusion in this study. 53.1% (n = 17) had asyrinx, and 78.1% (n = 25) had a pre-operative headache. All were treated with suboccipital craniectomy, C1 laminectomy (with or without C2 laminectomy), and durotomy. The dura was either left open by dural hitching (n = 23) or closed with surgicel and tisseel overlay graft (n = 9). We found a statistically significant association between the method of dural closure and the rate of syrinx resolution. Resolution occurred in 91.7% (n = 11) of the hitching group, compared to 20.0% (n = 1) of the overlay graft group: Χ2(1) = 5.6, p = .018. There were no statistically significant differences between the two groups in the rates of headache resolution or other complications.Conclusions: In patients with symptomatic Chiari I malformation and associated syringomyelia, syrinx resolution is more likely if the dura is hitched open rather than closed bysurgicel and tisseel overlay graft after durotomy.

MINIMALLY INVASIVE INSERTION OF SYRINGOSUBARACHNOID SHUNT FOR POSTTRAUMATIC SYRINGOMYELIA

Symptomatic posttraumatic syringomyelia affects up to 10% of patients with spinal cord injuries and manifests in a delayed manner as progressive sensorimotor changes below the level of the syrinx. Syrinx shunting, and in particular syringosubarachnoid shunting (SSAS), provides neurological improvement or stabilization in at least 50% of these patients. Given the debilitated condition of many of these patients, a minimally invasive approach to the insertion of these devices is desirable. We provide the first report of an SSAS inserted in a minimally invasive fashion through a tubular retractor. A 27-year-old woman presented 4 years after C6 to C7 fracture dislocation and incomplete spinal cord injury with increasing pain and spasticity below the midthoracic region. Magnetic resonance imaging scan revealed a midthoracic syrinx that had enlarged on serial imaging. SSAS was inserted using a minimally invasive technique via the X-Tube retractor (Medtronic Sofamor Danek, Memphis, TN). Through a 2.5-cm incision, hemilaminotomy was performed, and a midline durotomy and myelotomy were opened for SSAS insertion under microscopic visualization. Intraoperative ultrasonography revealed successful syrinx decompression after SSAS insertion. The operative time was 150 minutes and estimated blood loss was less than 100 mL. The patient was mobilized on postoperative Day 1 and was discharged 38.5 hours after surgery with resolution of her preoperative symptoms. Postoperative magnetic resonance imaging scan revealed excellent decompression of the syrinx, and through 1 year of follow-up, the patient has had no recurrence of her syrinx-related symptoms. This is the first report of minimal-access insertion of an SSAS. The minimally invasive technique appears to be a safe and effective means of implanting an SSAS. This approach allows for diminished blood loss and early mobilization and transfer to rehabilitation units for these patients.

Value of Treating Primary Causes of Syrinx in Scoliosis Associated with Syringomyelia

Retrospective chart and radiologic analysis. To analyze the value and risks of neurosurgical procedures for syringomyelia and of fusion procedures for scoliosis. There are few reports on the benefit of neurosurgical procedures on scoliosis, as well as the risk of fusion procedures on scoliosis related to syringomyelia. The 105 patients who had both scoliosis and syringomyelia were subdivided into three groups: (I) 59 patients without congenital scoliosis or myelomeningocele, (II) 20 patients with congenital scoliosis and syringomyelia, and (III) 26 patients with myelomeningocele and syringomyelia. The study evaluated: (1) The effect of either suboccipital craniectomy or direct shunting on the syrinx, the curvature, and the neurologic status; (2) the neurologic risk of scoliosis fusion surgery; and (3) the curve status after fusion surgery. In Group I (patients without congenital scoliosis or myelomeningocele), suboccipital craniectomy resulted in curve improvement in seven, worsening in three, and no change in two, whereas direct syrinx shunting gave curve improvement in none, curve worsening in six, and no change in two. In Groups II and III, no patient had curve improvement after neurosurgery. Group III had the highest rate of subsequent neurosurgery (50%). The subsequent neurosurgery was nearly always suboccipital craniectomy or detethering of the cord. Three of 38 patients (8%) had neurologic worsening when scoliosis fusion surgery was done without previous syrinx decompression. In patients without myelomeningocele or congenital scoliosis, but with Arnold-Chiari malformation and syringomyelia, suboccipital craniectomy gave the best chance for syrinx reduction and scoliosis improvement, particularly in children younger than 10 years. Syrinx shunting improved none of the scolioses. For syrinxes in patients with congenital scoliosis or myelomeningocele, neither neurosurgical procedure resulted in curve improvement, as other causes of scoliosis (vertebra anomalies, paralysis) remained untreated. Patients with myelomeningocele require a multipronged surgical approach to address all causes of syrinx, thus minimizing the potential need for repeat neurosurgery. Scoliosis correction without prior syrinx decompression carries a high neurologic risk.

Intraoperative measurement of spinal cord blood flow in syringomyelia

The role of spinal cord ischemia in the pathophysiology of syringomyelia remains undetermined. Previous reports in the literature suggest that shunting of syringes can improve spinal cord blood flow. In order to determine the effects of syrinx decompression on spinal cord blood flow in patients with syringomyelia, we prospectively measured regional spinal cord blood flow (RSCBF) intraoperatively pre and post shunting in patients with symptomatic syringomyelia using laser doppler flowmetry. Six patients with MRI documented syringomyelia were studied (three with Arnold Chiari I malformation and associated syrinx and three with post-traumatic syringomyelia). Surgery was performed on all patients with either a syringopleural or syringoperitoneal shunt. Laser doppler blood flow and somatosensory evoked potentials were monitored prior to myelotomy and after shunt insertion. Results indicate that there was a significant increase in RSCBF after decompression of the syrinx. This study supports the hypothesis that spinal cord ischemia is important in the pathophysiology of syringomyelia and confirms previous reports in the literature regarding RSCBF in syringomyelia.

Treatment of terminal syringomyelia in association with tethered cord syndrome: clinical outcomes with and without syrinx drainage

Current use of magnetic resonance (MR) imaging has led to increased awareness of the frequency of terminal syringomyelia in patients with tethered cord syndrome. However, that the surgical treatment of terminal syringomyelia is necessary remains unclear. In this study the authors attempted to assess the clinical impact, if any, brought after syrinx decompression on the clinical outcome of tethered cord syndrome. They randomly assigned 30 cases of pediatric tethered cord into two treatment groups: those in whom an untethering procedure was performed (Group I) and those in whom this procedure was combined with syrinx decompression (Group II). The 1-year follow-up clinical results obtained in the two groups, in correlation with MR imaging findings, were compared to evaluate the benefit of added syrinx drainage. Clinical follow-up evaluation revealed that surgical drainage of the syrinx, when combined with spinal cord untethering, resulted in better outcomes in terms of resolution of sensory deficits (p = 0.036) and bladder dysfunction (p = 0.05). The improvement in clinical outcome correlated with the radiologically documented resolution of the syrinx cavity; however, response rates of symptoms differed for each tethering subgroup. Preliminary results of this study indicated that terminal syringomyelia should be considered as a comorbidity that contributes to the clinical outcome of patients with tethered cord syndrome. A better clinical outcome is achieved following successful decompression of the syrinx in addition to untethering the spinal cord. These findings emphasize the importance of recognizing, evaluating, and treating this pathological entity.

Terminal syringomyelia in association with the tethered cord syndrome.

With the increasing use of magnetic resonance imaging, terminal syringomyelia (segmental cystic dilation of the caudal one-third of the spinal cord) in association with the tethered cord syndrome has become an appreciable finding. This study attempted to define the clinical significance of this associated pathological condition by describing its clinical and radiological characteristics and its contribution to the clinical status of patients with tethered spinal cords. Of 132 consecutive patients with tethered cord syndrome who presented to our department between 1990 and 1997, 32 patients with terminal syringomyelia were enrolled in this study. Clinical findings were correlated with syrinx morphological features, as defined using magnetic resonance imaging. Surgical treatment used two basic approaches, i.e., simple untethering or untethering with concurrent syrinx drainage. Analysis of the neurological deficits established a contribution of segmental symptoms, which were correlated with the extension and dilation of the syrinx cavity. Magnetic resonance imaging scans revealed the frequency of sacral tethering (40.6%), the intramedullary paracentral position of the syrinx (75%), and disturbances in regional cerebrospinal fluid flow (42%). The clinical outcomes seemed to be correlated with syrinx shrinkage; all patients who experienced collapse of the cavity achieved better symptom resolution. Radiologically significant terminal syringomyelia affects the clinical presentation of tethered cord syndrome, by increasing or inducing neurological deficits. Better clinical outcomes after syrinx decompression emphasize the importance of the recognition and treatment of this pathological condition.

Intramedullary pressure in syringomyelia: clinical and pathophysiological correlates of syrinx distension.

The pathophysiological effects of syrinx distension are incompletely understood. Although it is generally assumed that the accumulation of fluid within syrinx cavities can contribute to neurological dysfunction, there are no reports describing intramedullary pressure in syringomyelia. The purpose of the current study was to measure syrinx pressures in patients with progressive clinical deterioration and to correlate these data with neurological deficits and intraoperative physiological findings. Intramedullary fluid pressure was measured manometrically in 32 patients undergoing syrinx shunting procedures. The data were correlated with syrinx morphology, intraoperative somatosensory evoked potentials, laser Doppler measurements of local spinal cord blood flow (six patients), and neurological findings before and after syrinx decompression. Syrinx pressures recorded under atmospheric conditions ranged from 0.5 to 22.0 cm H2O (mean = 7.7 cm). There was a significant elevation of the cardiac pulse (mean = 0.7 cm H2O) and the respiratory pulse (mean = 1.1 cm H2O) that was consistent with raised cerebrospinal fluid pressure. Syrinx pressures decreased to subatmospheric levels after surgical drainage. In 18 of 24 patients with predrainage somatosensory evoked potential abnormalities, syrinx decompression produced a consistent reduction of N20 latencies (mean change = 0.49 ms +/- 0.094 SE right, P = 0.002; 0.61 ms +/- 0.089 SE left, P = 0.001) and a similar but less consistent increase in N20 amplitudes (mean change = 0.17 mV +/- 0.103 SE right, P = 0.115; 0.31 mV +/- 0.097 SE left, P = 0.027). Measurements of local spinal cord blood flow revealed very low baseline values (mean = 12.2 arbitrary units +/- 13.9 standard deviation), which increased to intermediate levels (mean = 144.7 arbitrary units +/- 42.6 standard deviation) after syrinx decompression. Patients with syrinx pressures greater than 7.7 cm H2O tended to have more rapidly progressive symptoms, exhibited greater improvements after shunting, and had a higher incidence of postoperative dysesthetic pain. The current study is the first to measure intramedullary pressure in a human disease. Evidence is presented that distended syringes are associated with varying levels of raised intramedullary pressure that can accentuate or induce neurological dysfunction by the compression of long tracts, neurons, and the microcirculation. Symptoms referrable to raised intramedullary pressure are potentially reversible by syrinx decompression.

Intraoperative improvement of somatosensory evoked potentials and local spinal cord blood flow in patients with syringomyelia.

This report is the first to correlate data concerning intraoperative somatosensory evoked potentials (SSEPs) and local spinal cord blood flow (ISCBF) in patients with syringomyelia. In a consecutive study, bilateral median nerve SSEPs were recorded intraoperatively in 13 patients undergoing a syrinx shunt to the posterior fossa cisterns (syringocisternostomy). ISCBF was measured in five of these patients using laser doppler flowmetry (LDF) calibrated in arbitrary units (AU). SSEP recordings obtained 30 min after syrinx decompression demonstrated a slight but consistent reduction of N20 latencies (mean change: 0.53 ms right, p < 0.003; 0.58 ms left, p < 0.001) concurrent with a similar but less consistent increase of N20 amplitudes (0.16 mV right, p = 0.256; 0.29 mV left, p = 0.03). Prior to shunting, LDF recordings from the spinal cord overlying syrinxes revealed very low ISCBF values in five of five patients (mean LDF, 13.2 AU +/- 15.3 SD). Immediately after shunting, there was a dramatic rise of ISCBF (mean LDF, 241.2 AU +/- 106.3 SD) associated with visualized hyperemia of the spinal cord and pial vessels. The ISCBF fell to intermediate levels after 2 min (157.2 AU +/- 33.0 SD) and remained at these levels during the interval of recording (5 min). Hyperventilation testing in two patients prior to shunting revealed no change in ISCBF consistent with a loss of CO2 vascular reactivity and a paradoxical increase of ISCBF in one patient 5 min after shunting. Each patient in this study experienced neurological improvement in the immediate postoperative period associated with collapse or disappearance of the syrinx on magnetic resonance imaging scans. Because syrinx shunting results in an acute decompression of the distended spinal cord, it is possible that the rapid improvement of SSEPs reflects a relief of mechanical factors such as stretching and compression of nervous tissue. However, the LDF findings in this study suggest that distended spinal cord cavities are also capable of producing regional ischemia. A significant reduction of ISCBF is a possible contributing cause of neurological injury and SSEP abnormalities. Intraoperative improvement of SSEPs and ISCBF were found to correlate well with neurological recovery following syringocisternostomy. Our results indicate that SSEP monitoring can provide useful information during surgical procedures for syringomyelia and that further experience with LDF monitoring may provide insights into the pathophysiology of this condition.

Syringomyelia and developmental scoliosis.

We attempted to characterize the signs and symptoms of patients presenting with scoliosis as a manifestation of occult syringomyelia, and to determine the effect of syrinx decompression on the deformity and neurologic deficits. This study represented 21 patients treated from 1981 through 1991 at the authors' institution. All patients with occult syringomyelia and no other central nervous system lesions underwent decompression of the syrinx, with improvement in neurologic signs and symptoms. Three of the four with scoliosis that were not treated by arthrodesis showed improvement of their deformity at an average follow-up of 35 months. Three of five patients with myelodysplasia, occult syringomyelia, and scoliosis not previously treated with spinal arthrodesis showed stabilization or improvement of their deformity at an average follow-up of 21 months. We conclude that syringomyelia is associated with a high incidence of developmental scoliosis, and that decompression of the syrinx leads to improvement in, or stabilization of, the majority of scoliotic curves, or postpones the need for fusion.

MRI measurement of syrinx size before and after operation.

When patients with syringomyelia fail to improve after operation, factors such as incomplete cyst decompression or type of operation are often implicated. MRI has been used to confirm adequate syrinx decompression post-operatively and to compare the degree of collapse with the type of operation. Foramen magnum decompression was at least as effective in reducing cyst size as syringo-subarachnoid shunting. MRI may also provide a better classification of syringomyelia.