A critical appraisal of syrinx cavity shunting procedures

Foramen magnum decompression with cervical syringotomy for Chiari malformation type I with syringomyelia - A useful adjunct in selected cases

Background

Persistent or worsening syringomyelia after foramen magnum decompression (FMD) for Chiari I malformation (CIM) can be challenging to manage. We present a previously unpublished surgical technique of FMD with concomitant cervical syringotomy in selected patients.

Methods

A retrospective analysis of prospectively collected data was carried out. Patients who underwent FMD and expansion duraplasty (FMDD) with concomitant syringotomy were collected.

Results

Three patients with CIM with high cervical syringomyelia who underwent FMDD with concurrent syringotomy were identified. All cases had an idiopathic CIM. Improvement in clinical symptoms was noticed in all patients. Early postoperative imaging (within 6 weeks-4 months) showed syrinx transverse diameter reduction in the range of 85-100%. There were no postoperative complications.

Conclusion

FMDD with concurrent high cervical syringotomy through a standard approach in selected cases of CIM with high cervical syringes achieves clinical improvement without additional complications.

Intraoperative Neurophysiological Monitoring in Syringomyelia Surgery: A Multimodal Approach

Syringomyelia can be associated with multiple etiologies. The treatment of the underlying causes is first-line therapy; however, a direct approach to the syrinx is accepted as rescue treatment. Any direct intervention on the syrinx requires a myelotomy, posing a significant risk of iatrogenic spinal cord (SC) injury. Intraoperative neurophysiological monitoring (IONM) is crucial to detect and prevent surgically induced damage in neural SC pathways. We retrospectively reviewed the perioperative and intraoperative neurophysiological data and perioperative neurological examinations in ten cases of syringomyelia surgery. All the monitored modalities remained stable throughout the surgery in six cases, correlating with no new postoperative neurological deficits. In two patients, significant transitory attenuation, or loss of motor evoked potentials (MEPs), were observed and recovered after a corrective surgical maneuver, with no new postoperative deficits. In two cases, a significant MEP decrement was noted, which lasted until the end of the surgery and was associated with postoperative weakness. A transitory train of neurotonic electromyography (EMG) discharges was reported in one case. The surgical plan was adjusted, and the patient showed no postoperative deficits. The dorsal nerve roots were stimulated and identified in the seven cases where the myelotomy was performed via the dorsal root entry zone. Dorsal column mapping guided the myelotomy entry zone in four of the cases. In conclusion, multimodal IONM is feasible and reliable and may help prevent iatrogenic SC injury during syringomyelia surgery.

Syrinx shunts for syringomyelia: a systematic review and meta-analysis of syringosubarachnoid, syringoperitoneal, and syringopleural shunting

OBJECTIVE

Syringomyelia is a debilitating, progressive disease process that can lead to loss of neurological function in patients already experiencing significant compromise. Syringosubarachnoid, syringoperitoneal, and syringopleural shunts are accepted treatment options for patients with persistent syringomyelia, but direct comparisons have been lacking to date. The authors conducted a systematic review of the literature and meta-analysis to compare clinical outcomes between these three syrinx shunt modalities.

METHODS

Utilizing PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for systematic reviews, Ovid Embase, PubMed, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, American College of Physicians Journal Club, and Database of Abstracts of Review of Effectiveness were searched to identify all potentially relevant studies published from inception until July 2020. Data were extracted and analyzed using meta-analysis of proportions. The primary study outcome was the rate of reoperation based on the initial shunt modality. Secondary outcomes included clinical improvement, clinical deterioration, and complications following shunt placement.

RESULTS

A total of 22 articles describing 27 distinct treatment cohorts published between 1984 and 2019 satisfied the inclusion criteria. This captured 473 syrinx shunt procedures, 193 (41%) by syringosubarachnoid shunt, 153 (32%) by syringoperitoneal shunt, and 127 (27%) by syringopleural shunt, with an overall median clinical follow-up of 44 months. The pooled incidences of revision surgery were estimated as 13% for syringosubarachnoid, 28% for syringoperitoneal, and 10% for syringopleural shunts, respectively (p-interaction = 0.27). The rate of clinical improvement was estimated as 61% for syringosubarachnoid, 64% for syringoperitoneal, and 71% for syringopleural shunts. The rate of clinical deterioration following placement was estimated as 13% for syringosubarachnoid, 13% for syringoperitoneal, and 10% for syringopleural shunts.

CONCLUSIONS

The preferred modality of syrinx shunting remains a controversial topic for symptomatic syringomyelia. This study suggests that while all three modalities offer similar rates of clinical improvement and deterioration after placement, syringoperitoneal shunts have a greater rate of malfunction requiring surgical revision. These data also suggest that syringopleural shunts may offer the best rate of clinical improvement with the lowest rate of reoperation.

Leptomeningeal pneumocephalus and pneumorrhachis: Signs of pneumothorax in case of syringopleural shunting

In this article, we present a case of leptomeningeal pneumocephalus and pneumorrhachis secondary to pneumothorax that occurred six years after syringopleural shunting.

Syringomyelia: diagnosis and management

In the pre-MR era syringomyelia often presented late, as a crippling neurological disorder. Today, most cases are diagnosed earlier, with less pronounced deficits. We are therefore presented with new challenges, including understanding the significance of various presenting symptoms, knowing when surgery might help and being aware of other treatments that could benefit someone living with the effects of syringomyelia, or its underlying cause.

Chronic extradural compression of spinal cord leads to syringomyelia in rat model

Background

Syringomyelia is a common spinal cord lesion. However, whether CSF blockage is linked to the formation and enlargement of syringomyelia is still controversial. The current model of syringomyelia needs modification to more closely mimic the clinical situation.

Methods

We placed cotton strips under the T13 lamina of 40 8-week-old rats and blocked CSF flow by extradural compression. After 4 and 8 weeks, MRI was performed to evaluate the morphology of syringomyelia and the ratio of spinal cord diameter to syrinx diameter calculated. Locomotor function was evaluated weekly. Spinal cord sections, staining and immunohistochemistry were performed 8 weeks after surgery, the ratio of the central canal to the spinal cord area was calculated, and ependymal cells were counted. In another experiment, we performed decompression surgery for 8 rats with induced syringomyelia at the 8th week after surgery. During the surgery, the cotton strip was completely removed without damaging the dura mater. Then, the rats received MRI imaging during the following weeks and were sacrificed for pathological examination at the end of the experiment.

Results

Syringomyelia formed in 82.5% (33/40) of rats at the 8-week follow-up. The Basso, Beattie and Bresnahan (BBB) scores of rats in the experimental group decreased from 21.0±0.0 to 18.0 ±3.9 in the first week after operation but returned to normal in later weeks. The BBB score indicated that the locomotor deficit caused by compression is temporary and can spontaneously recover. MRI showed that the syrinx is located in the center of the spinal cord, which is very similar to the most common syringomyelia in humans. The ratio of the central canal to the spinal cord area reached (2.9 ± 2.0) × 10⁻², while that of the sham group was (5.4 ± 1.5) × 10⁻⁴. The number of ependymal cells lining the central canal was significantly increased (101.9 ±  39.6 vs 54.5 ± 3.4). There was no syrinx or proliferative inflammatory cells in the spinal cord parenchyma. After decompression, the syringomyelia size decreased in 50% (4/8) of the rats and increased in another 50% (4/8).

Conclusion

Extradural blockade of CSF flow can induce syringomyelia in rats. Temporary locomotor deficit occurred in some rats. This reproducible rat model of syringomyelia, which mimics syringomyelia in humans, can provide a good model for the study of disease mechanisms and therapies.

MINIMALLY INVASIVE TREATMENT OF IDIOPATHIC SYRINGOMYELIA USING MYRINGOTOMY T-TUBES: A CASE REPORT AND TECHNICAL NOTE

Syringomyelia is characterized by a fluid-filled cavity within the spinal cord. Expansion of the syrinx often results in the clinical course of progressive neurologic deficit. Surgery for syringomyelia generally aims to treat the underlying cause, if it is known. However, little is known about idiopathic syringomyelia, which requires specific management. In our paper, an alternative, minimally invasive treatment option for large symptomatic idiopathic cervicothoracic syrinx is described and discussed. We present a case of a 44-year-old male without a history of spinal cord trauma, infection, or other pathologic processes, who presented for thoracic pain. Due to progressive pain and left leg paresis, magnetic resonance imaging (MRI) was performed and revealed extensive septated syringomyelia from T5 to T7 and hydromyelia cranially. We applied minimally invasive technique for shunting the idiopathic syrinx into the subarachnoid space using two Richards modified myringotomy T-tubes. Postoperative MRI revealed significant decrease in the syrinx size and clinical six-month follow-up showed improvement of clinical symptoms. This minimally invasive treatment of syringomyelia was found to be an effective method for idiopathic septated syrinx, without evident underlying cause. However, long-term follow-up and more patients are necessary for definitive evaluation of this technique.

Chiari malformation and syringomyelia

Chiari malformation was first described over a century ago, and consists of posterior fossa anomalies that generally share the feature of cerebellar tonsillar descent through the foramen magnum. Our understanding of this disorder was initially based on autopsy studies, and has been greatly enhanced by the advent of MRI. The surgical management of Chiari anomalies has also evolved in a parallel fashion. Although the exact surgical technique varies among individual surgeons, the goals of surgery remain constant and consist of relieving brainstem compression and cranial nerve distortion, restoring the normal flow of CSF across the foramen magnum, and reducing the size of any associated syrinx cavity. Syrinx cavities are most commonly associated with Chiari anomalies, yet primary spinal syringomyelia (PSS) can be caused by traumatic, infectious, degenerative, and other etiologies that cause at least a partial CSF flow obstruction in the spinal subarachnoid space. As with syringomyelia associated with Chiari anomalies, the main goal of PSS surgery is to reestablish CSF flow across the area of obstruction. In addition to MRI, myelography with CT can be very helpful in the evaluation and management of these patients by identifying focal regions of CSF obstruction that may be amenable to surgical intervention. Future directions for the treatment of Chiari anomalies and syringomyelia include the application of advanced imaging techniques, more widespread use of genetic evaluation, large-scale outcome studies, and the further refinement of surgical technique.

Direct syrinx drainage in patients with Chiari I malformation

While FMD is, to date, the primary treatment of symptomatic CM I, the treatment of Chiari malformation type I (CM I) associated syrinx remains controversial. In cases of persistent, progressive, or recurrent syrinx following FMD, direct syrinx drainage (DSD) is described as a safe and efficient option, leading to a good clinical and radiological outcome. However, studies at hand mostly include very heterogeneous patient populations, small cohorts, and are of retrospective nature. We provide an overview of the possible indications and outcome for DSD in CM I-associated syrinx. We discuss the different surgical techniques of DSD and review the available literature comparing different DSD techniques. Finally, we discuss the possible complications that might occur after DSD and how they can be prevented.

Effect of extradural constriction on CSF flow in rat spinal cord

Background

Fluid homeostasis in the central nervous system (CNS) is essential for normal neurological function. Cerebrospinal fluid (CSF) in the subarachnoid space and interstitial fluid circulation in the CNS parenchyma clears metabolites and neurotransmitters and removes pathogens and excess proteins. A thorough understanding of the normal physiology is required in order to understand CNS fluid disorders, including post-traumatic syringomyelia. The aim of this project was to compare fluid transport, using quantitative imaging of tracers, in the spinal cord from animals with normal and obstructed spinal subarachnoid spaces.

Methods

A modified extradural constriction model was used to obstruct CSF flow in the subarachnoid space at the cervicothoracic junction (C7–T1) in Sprague–Dawley rats. Alexa-Fluor 647 Ovalbumin conjugate was injected into the cisterna magna at either 1 or 6 weeks post–surgery. Macroscopic and microscopic fluorescent imaging were performed in animals sacrificed at 10 or 20 min post–injection. Tracer fluorescence intensity was compared at cervical and thoracic spinal cord levels between control and constriction animals at each post-surgery and post-injection time point. The distribution of tracer around arterioles, venules and capillaries was also compared.

Results

Macroscopically, the fluorescence intensity of CSF tracer was significantly greater in spinal cords from animals with a constricted subarachnoid space compared to controls, except at 1 week post-surgery and 10 min post-injection. CSF tracer fluorescence intensity from microscopic images was significantly higher in the white matter of constriction animals 1 week post surgery and 10 min post-injection. At 6 weeks post–constriction surgery, fluorescence intensity in both gray and white matter was significantly increased in animals sacrificed 10 min post-injection. At 20 min post-injection this difference was significant only in the white matter and was less prominent. CSF tracer was found predominantly in the perivascular spaces of arterioles and venules, as well as the basement membrane of capillaries, highlighting the importance of perivascular pathways in the transport of fluid and solutes in the spinal cord.

Conclusions

The presence of a subarachnoid space obstruction may lead to an increase in fluid flow within the spinal cord tissue, presenting as increased flow in the perivascular spaces of arterioles and venules, and the basement membranes of capillaries. Increased fluid retention in the spinal cord in the presence of an obstructed subarachnoid space may be a critical step in the development of post-traumatic syringomyelia.

Electronic supplementary material

The online version of this article (10.1186/s12987-019-0127-8) contains supplementary material, which is available to authorized users.

Syringobulbia: A delayed complication following spinal cord injury - case report

CONTEXT

Syringobulbia is a very rare progressive disorder of central nervous system, with several possible underlying conditions. Rarely, it is also encountered as a late complication of syringomyelia.

FINDINGS

In the present manuscript, a case of a paraplegic patient, due to traumatic spinal cord injury (thoracolumbar fracture), presenting after years progressively developing symptoms of the lower cranial nerves and upper extremities, owed to syringomyelia and syringobulbia, the surgical treatment applied and its outcomes are described. We performed a syringo-peritoneal shunting procedure using a T-tube. The patient's symptoms resolved postoperatively and the cavity's size was reduced to a great degree.

CONCLUSION/CLINICAL RELEVANCE

The late appearance of cranial nerve deficits or symptoms-signs of the upper extremities in a patient with traumatic thoracic spinal cord injury should raise suspicion that post-traumatic syringomyelia or syringobulbia has occurred. In such cases, radiologic evaluation and early surgical drainage of the cyst as a means of preventing significant delayed neurologic deficit is advocated.

Treatment of Holocord Syringomyelia-Chiari Complex by Posterior Fossa Decompression and a Syringosubarachnoid Shunt in a Single-Stage Single Approach

BACKGROUND

Posterior fossa decompression with expansive duraplasty is the first-line surgical approach for the treatment of symptomatic syringomyelia associated with Chiari malformation. Despite good decompression, the clinical failure rate is reported to be up to 26%. A syringosubarachnoid (S-S) shunt may be used as a secondary option.

METHODS

In this paper we describe a single-institution experience of three cases of holocord syringomyelia-Chiari complex treated with foramen magnum decompression, expansive duraplasty and an S-S shunt carried out in a single-stage single approach. Following a standard suboccipital craniectomy, patients were submitted to syrinx fenestration and simultaneous insertion of an S-S shunt through a 1-mm posterior midline myelotomy at the C2 level prior to expansive dural reconstruction.

RESULTS

Postoperative imaging showed immediate reduction of the holocord cavities. Preoperative neurological deficits rapidly improved significantly and were stabilized at follow-up.

CONCLUSION

In our experience the positioning of the shunt catheter at a high level of the spinal cord (C2) did not add a significant risk of morbidity and obviated the need for a second operation and/or a separate incision in cases of clinical failure. This technique avoided the risk associated with a second surgery and its morbidity, and allowed prompt clinical recovery.

A simple technique for thoracoscopic assisted placement of the distal limb of syringopleural shunts

Background

Syringomyelia is an unusual accumulation of fluid within the spinal cord that may be associated with significant neurologic symptoms. Surgical drainage using various techniques is often required to reduce the intraparenchymal pressure and to alleviate symptoms. Syringopleural shunting seems to produce best results.

Patients and methods

A simple technique to insert the distal limb of the syringopleural shunt into the pleural space is described in detail. The patient is placed in prone position. The syrinx is accessed from a dorsal incision and the proximal limb is inserted into the fluid cavity. The tube is tunneled through the subcutaneous space laterally and caudally. A 5mm blunt port is inserted lateral to the scapula and advanced under visual control using a 5mm 30° camera through the subcutaneous tissue and muscle and at the upper border of the 5th rib through the intercostals. With ventilation paused, the pleura is penetrated and CO2 is insufflated with a pressure of 8mm mercury. Under visual control the distal limb of the shunt is inserted at the pleural recessus and the tube is directed cranially. Positive airway pressure is applied re-expanding the lung. The trocar is removed from the pleural cavity and the skin is closed with subcuticular sutures.

Results

The shunt was successfully placed in three consecutive cases including one redo case (1 male, 1 female aged 50 and 51 years with post traumatic syrinx). Postoperative chest x-ray excluded pneumothorax and no chest tube was required. Neurologic improvement was achieved in both patients.

Conclusions

General surgeons should be familiar with this simple technique similar to laparoscopic assisted placement of distal ventriculoperitoneal shunt catheters into the abdominal cavity.

[Treatment of syringomyelia associated with adhesive arachnoiditis]

The prevalence of syringomyelia (SM) caused by adhesive arachnoiditis (AA) is 2 to 4 cases per 100000 population. Surgical treatment of this pathology usually includes implantation of shunts into the cyst cavity or opening and drainage of the cavity. In this case, SM continues to progress in 72-100% of patients. Unsatisfactory outcomes of this surgical approach necessitate searching for other treatment options.

PURPOSE

To define the optimal amount of surgery for SM associated with AA and the criteria for assessment of surgery outcomes.

MATERIAL AND METHODS

The authors treated 47 SM patients in the period from 2010 to 2015. Of these, 34 (72.3%) patients underwent surgery; a total of 40 operations were performed. The patients' age ranged from 18 to 64 years (mean, 43.5 years). Tethering of the spinal cord was eliminated in 25 patients; 9 patients underwent cyst shunting.

RESULTS

Among operated patients, 5 patients had grade 1 arachnopathy, 13 patients had grade 2 arachnopathy, 12 patients had grade 3 arachnopathy, and 4 patients had grade 4 arachnopathy. The minimal postoperative follow-up period was 11 months. After shunting, the condition improved in 8 of 9 patients; in 7 patients, the condition returned to the baseline level within the first postoperative year; in 6 (66.7%) of these patients, the disease continued to progress. After surgical release of spinal cord tethering, satisfactory long-term results were achieved in 13 (86.6%) patients with grade 1-2 arachnopathy. In 3 (50%) patients with grade 3 arachnopathy, the condition was stabilized. Among patients with grade 4 arachnopathy, progression of the disease was stopped in 1 patient; the condition worsened in 2 (50%) patients. Among all the operated patients, complications developed in 7 patients. There were no lethal outcomes.

CONCLUSIONS

In grade 1-2 arachnopathy, progression of SM after release of spinal cord tethering occurs only in 13.4% of patients. Therefore, release of spinal cord tethering is recommended for these patients. In grade 3-4 arachnopathy, the rate of relapse after this surgery is more than 80%. Therefore, given the simplicity and a lower risk of complications of cyst shunting, this procedure is advisable for these patients.

Intradural cavernous lymphangioma of the thoracic spine: case report, technical considerations, and review of the literature

BACKGROUND CONTEXT

Cavernous lymphangioma is a rare slow-growing tumor that can cause neurologic compromise when it involves the central nervous system. Involvement of the spinal column is rare but may involve the osseous structures or the epidural space of the spinal column.

PURPOSE

We report the first case of an intradural, extramedullary cavernous lymphangioma involving the thoracic spinal cord.

METHODS

An 83-year-old woman presented with progressive gait ataxia, bilateral lower extremity weakness, and a band-like sensation in the middle and lower thoracic dermatomes. Magnetic resonance imaging of the thoracic spinal cord revealed hyperintensity on T2 and enhancement of an intradural cystic mass along the dorsal aspect of the T5-T8 levels with significant compression of the spinal cord.

RESULTS

Complete surgical resection was difficult owing to the adherence of the tumor to the pial surface and microvasculature of the thoracic spinal cord. Recurrence of the mass was ultimately treated with cystic fluid diversion into the peritoneum. At her follow-up visit after 28 months, the patient was able to ambulate with minimal assistance. A comparative literature review is presented. There are no reports of intradural thoracic spinal cord involvement in the literature.

CONCLUSIONS

Intradural cavernous lymphangioma of the spine poses a unique surgical challenge for complete resection. Cystic fluid diversion appears to be a viable treatment option with lasting benefit if complete resection is not achieved.

Does Surgical Correction of Right Thoracic Scoliosis in Syringomyelia Produce Outcomes Similar to Those in Adolescent Idiopathic Scoliosis?

BACKGROUND

Practice guidelines for deformity correction in patients with syringomyelia-associated scoliosis (SMS) remain ill defined. Although surgeons experienced in treating adolescent idiopathic scoliosis (AIS) are commonly called on to treat SMS, no study has directly compared the results of surgical treatment between patients with SMS and those with AIS. The present study was performed to compare the radiographic and clinical outcomes of posterior spinal fusion between patients with right-thoracic SMS and those with right-thoracic AIS.

METHODS

Sixty-nine adolescents with SMS were matched with patients with AIS for sex, age, and curve magnitude. Patients were evaluated before surgery, immediately after surgery, and at the latest follow-up examination for changes in curve correction, global coronal balance, and scores on the Scoliosis Research Society (SRS)-22 questionnaire.

RESULTS

The preoperative primary curve magnitude was similar between the two groups, but a trend toward less flexibility was observed in the SMS group. The amount of correction of the thoracic Cobb angles obtained surgically (68% compared with 71%) and the ratio of percent correction to flexibility (1.80 compared with 1.76) were similar in the SMS and AIS groups. At the latest evaluation, eight patients with SMS and five with AIS had lost >10° of thoracic spine correction (p = 0.382). The postoperative coronal decompensation averaged 13% and 6%, respectively, in the SMS and AIS groups (p = 0.243). No intergroup differences were noted with respect to the sagittal vertical axis or proximal junctional change, with preservation of global sagittal balance in both groups during follow-up. There were no neurologic or other major complications related to surgery in either group.

CONCLUSIONS

Despite the differences in preoperative status, adolescents with idiopathic right thoracic scoliosis and those with syringomyelia-associated right thoracic scoliosis had comparable clinical and radiographic outcomes of pedicle-screw-based posterior spinal fusion, without neurologic complications.

Syringosubarachnoid shunting using a myringotomy tube

BACKGROUND

Syringomyelia results from obstruction of cerebrospinal fluid (CSF) flow due to a multitude of causes. Often symptoms of pain, weakness, and sensory disturbance are progressive and require surgical treatment. We present here a rare technique for syringosubarachnoid shunting.

CASE DESCRIPTION

We present the case of a 38-year-old male who suffered a traumatic cervical spinal cord injury due to a motor vehicle accident. With progressive pain and motor decline, a magnetic resonance imaging was obtained and showed a new syrinx extending cervical multiple segments. A unique surgical procedure using a myringotomy tube to shunt CSF into the subarachnoid space was employed in this case. The patient's examination stabilized postoperatively, and at 2 months and 6 months follow-up visits, his strength and sensation continued to improve.

CONCLUSION

We used a myringotomy tube for syringosubarachnoid shunting for the surgical management of a posttraumatic syrinx with good results. This technique minimizes suturing and may minimize shunt-related complications.

Intracranial hypotension after syringopleural shunting in posttraumatic syringomyelia: Case report and review of the literature

We report a case of a 45-year-old male with a syringopleural shunt who developed intracranial hypotension. The patient presented with 2 weeks history of worsening headache and back pain, on a background of having had a syringopleural shunt inserted for a thoracic posttraumatic syrinx. Computerized tomography imaging of the brain revealed bilateral subdural fluid collections. Magnetic resonance imaging appearances of spinal and intracranial pachymeningeal enhancement confirmed intracranial hypotension. We present a rare case of intracranial hypotension secondary to syringopleural shunting in a patient with posttraumatic syringomyelia.

Clinical Features of Post-Traumatic Syringomyelia

Objective

The purpose of this study was to analyze the clinical manifestations, radiological findings, treatment results, and clinical significance of post-traumatic syringomyelia (PTS).

Methods

We retrospectively reviewed the medical charts of nine surgical patients with symptomatic PTS between 1992 and 2012.

Results

The most common clinical manifestation was development of new motor weakness. The mean interval between the initial injury and the onset of new symptoms 21.9 years. The mean length of the syringes observed on preoperative magnetic resonance images was 7.8 spinal levels. Shunting procedures were performed in five patients. Four patients underwent arachnoidolysis and duraplasty. Patients developed mechanical shunt failure. Postoperatively, one patient showed clinical improvement, four patients were stable, and four patients showed deterioration.

Conclusion

PTS is a disabling sequelae of spinal cord injury, which develops months to years after spinal injury. We have to consider that patients with PTS may have poor long-term outcome.

Surgical treatment of idiopathic syringomyelia: Silastic wedge syringosubarachnoid shunting technique

Background:

The underlying pathophysiology leading to syringomyelia is elusive with multiple flow-related theories constituting our current limited understanding of the disease process. Syringomyelia is associated with pathologies related to the disturbance of cerebral spinal fluid flow found in conditions such as Chiari I malformations, spinal malignancy, spinal cord tethering, trauma, or arachnoid adhesions. Our aim is to describe a unique surgical shunting technique used to treat refractory cases of idiopathic syringomyelia.

Methods:

Five patients, aged 22-50, presented with progressive neurologic symptoms associated with an idiopathic syrinx. All underwent decompressive laminectomy surgery with syringosubarachnoid shunting using the silastic wedge technique.

Results:

In five cases of idiopathic syringomyelia, clinical and radiographic follow up ranges from 3 to 36 months. Three patients have radiographic and clinical follow up greater than 24 months. All patients improved clinically and their symptoms have been stable.

Conclusions:

Shunting procedures for the syringomyelia disease spectrum have been criticized due to the inconsistent long-term outcomes. This surgical technique used to treat symptomatic idiopathic syringomyelia has been devised based on our intraoperative experience, surgical outcomes, and evaluation of the literature. The purpose of the wedges is to preserve patency of the communication between the syrinx cavity and the expanded subarachnoid space by preventing healing of the myelotomy edges and by maintaining an artificial conduit between the syrinx cavity and the subarachnoid space. Although short-term results are promising, continued long-term follow up is needed to determine the ultimate success of the silastic wedge shunting procedure.

Worsening or development of syringomyelia following Chiari I decompression: case report

OBJECT

The effects of posterior fossa decompression on Chiari malformation Type I-induced syringomyelia have been well described. However, treatment of worsening syringomyelia after Chiari decompression remains enigmatic. This paper defines patient and clinical characteristics as well as treatment and postoperative radiological and clinical outcomes in patients experiencing this complication.

METHODS

The authors performed a retrospective review of patients at the Children's Hospital of Pittsburgh and Children's of Alabama who developed worsening syringomyelia after Chiari decompression was performed.

RESULTS

Fourteen children (age range 8 months to 15 years), 7 of whom had preoperative syringomyelia, underwent posterior fossa decompression. Aseptic meningitis (n = 3) and bacterial meningitis (n = 2) complicated 5 cases (4 of these patients were originally treated at outside hospitals). Worsening syringomyelia presented a median of 1.4 years (range 0.2-10.3 years) after the primary decompression. Ten children presented with new, recurrent, or persistent symptoms, and 4 were asymptomatic. Secondary Chiari decompression was performed in 11 of the 14 children. The other 3 children were advised to undergo secondary decompression. A structural cause for each failed primary Chiari decompression (for example, extensive scarring, suture in the obex, arachnoid web, residual posterior arch of C-1, and no duraplasty) was identified at the secondary operation. After secondary decompression, 8 patients' symptoms completely resolved, 1 patient's condition stabilized, and 2 patients remained asymptomatic. Radiologically, 10 of the 11 children had a decrease in the size of their syringes, and 1 child experienced no change (but improved clinically). The median follow-up from initial Chiari decompression was 3.1 years (range 0.8-14.1 years) and from secondary decompression, 1.3 years (range 0.3-4.5 years). No patient underwent syringopleural shunting or other nonposterior fossa treatment for syringomyelia.

CONCLUSIONS

Based on the authors' experience, children with worsening syringomyelia after decompression for Chiari malformation Type I generally have a surgically remediable structural etiology, and secondary exploration and decompression should be considered.

Post-traumatic syringomyelia: CSF hydrodynamic changes following spinal cord injury are the driving force in the development of PTSM

Post-traumatic syringomyelia (PTSM) is a disorder that occurs infrequently following spinal cord injury (SCI), characterized by progressive neurological deterioration resulting from syrinx expansion originating in proximity to the traumatic epicenter. Several pathogenetic factors are associated with this disorder, however, the precise mechanism of the development of PTSM is controversial. Combined anatomical alterations and molecular changes following trauma to the spinal cord and arachnoid participate in the development of this condition. These factors include narrowing or obstruction of the subarachnoid space (SAS), central canal occlusion, myelomalacia, and alterations in intramedullary water permeability. If a patient sustains a SCI with delayed progressive deterioration in neurological function, in association with the MRI appearance of syringomyelia (SM), the diagnosis of PTSM is straightforward. The treatment of PTSM has not undergone any significant changes recently. The surgical treatment of PTSM consists of reconstructing the SAS or shunting fluid away from the syrinx to other locations. The advantages and disadvantages of each procedure will be discussed. With greater understanding of the mechanisms contributing to the development of SM, including advanced diagnostic methods and further advances in the development of artificial dural and shunting tubing, future therapies of PTSM will be more effective and long-lasting. Incorporation of alterations of AQP4 expression provides an intriguing possibility for future treatment of PTSM.

Aquaporin-4 expression in post-traumatic syringomyelia

Aquaporin-4 (AQP4) is an astroglial water channel protein that plays an important role in the transmembrane movement of water within the central nervous system. AQP4 has been implicated in numerous pathological conditions involving abnormal fluid accumulation, including spinal cord edema following traumatic injury. AQP4 has not been studied in post-traumatic syringomyelia, a condition that cannot be completely explained by current theories of cerebrospinal fluid dynamics. Alterations of AQP4 expression or function may contribute to the fluid imbalance leading to syrinx formation or enlargement. The aim of this study was to examine AQP4 expression levels and distribution in an animal model of post-traumatic syringomyelia. Immunofluorescence and western blotting were used to assess AQP4 and glial fibrillary acidic protein (GFAP) expression in an excitotoxic amino acid/arachnoiditis model of post-traumatic syringomyelia in Sprague-Dawley rats. At all time-points, GFAP-positive astrocytes were observed in tissue surrounding syrinx cavities, although western blot analysis demonstrated an overall decrease in GFAP expression, except at the latest stage investigated. AQP4 expression was significantly higher at the level of syrinx at three and six weeks following the initial syrinx induction surgery. Significant increases in AQP4 expression also were observed in the upper cervical cord, rostral to the syrinx except in the acute stage of the condition at the three-day time-point. Immunostaining showed that AQP4 was expressed around all syrinx cavities, most notably adjacent to a mature syrinx (six- and 12-week time-point). This suggests a relationship between AQP4 and fluid accumulation in post-traumatic syringomyelia. However, whether this is a causal relationship or occurs in response to an increase in fluid needs to be established.

Radiographic and clinical outcome of syringomyelia in patients treated for tethered cord syndrome without other significant imaging abnormalities

OBJECT

The surgical management of patients with symptoms of tethered cord syndrome (TCS) who lack significant radiographic abnormalities is controversial. One potential MRI marker for TCS is a spinal cord syrinx or syringomyelia. Alternatively, a syrinx may be a benign and incidental finding. In this report the authors evaluated a highly selected cohort of patients with symptoms of TCS with minimal radiographic abnormalities other than syringomyelia. They analyzed clinical and radiographic outcomes after tethered cord release (TCR).

METHODS

A retrospective review of data from 16 children who met the study inclusion criteria was performed. All patients had been surgically treated at Riley Hospital for Children in Indianapolis, Indiana, between 2006 and 2011. All children had clinical symptoms of TCS as well as available pre- and postoperative MRI data.

RESULTS

The most common presentation (12 [75%] of 16 patients) was urinary dysfunction, defined as symptoms of urgency or incontinence with abnormal urodynamic studies. Clinical follow-up data were available in 11 of these 12 patients. All 11 had improvement in symptoms at an average follow-up of 17 months. Seven (87.5%) of 8 patients presenting with back or leg pain had improvement. Three patients had progressive scoliosis; 2 had stabilization of the curve or mild improvement, and 1 patient had worsening deformity. Radiographic follow-up data were obtained an average of 14.5 months after surgery. Twelve patients (75%) had stable syringomyelia after TCR. Four patients showed improvement, with 2 having complete radiographic resolution.

CONCLUSIONS

Highly selected patients with symptoms of TCS did very well clinically. Patients with abnormal urodynamic studies, pain, and gait disturbances showed a high rate of symptomatic improvement. However, a smaller percentage of patients had radiographic improvement of the syrinx. Therefore, the authors suggest that the decision to perform TCR should be based on clinical symptoms in this population. Symptomatic improvement was not necessarily related to radiographic resolution of the syrinx.

Neurological deterioration after foramen magnum decompression for Chiari malformation type I: old or new pathology?

OBJECT

Decompression of the foramen magnum is widely accepted as the procedure of choice for patients with Chiari malformation Type I (CM-I). This study was undertaken to determine the mechanisms responsible for neurological deterioration after foramen magnum decompression and the results of secondary interventions.

METHODS

Between 1987 and 2010, 559 patients with CM-I presented, 107 of whom had already undergone a foramen magnum decompression, which included a syrinx shunt in 27 patients. Forty patients who were neurologically stable did not undergo another operation. Sixty-seven patients with progressive symptoms received a recommendation for surgery, which was refused by 16 patients, while 51 patients underwent a total of 61 secondary operations. Hospital and outpatient records, radiographic studies, and intraoperative images were analyzed. Additional follow-up information was obtained by telephone calls and questionnaires. Short-term results were determined after 3 and 12 months, and long-term outcomes were evaluated using Kaplan-Meier statistics.

RESULTS

Sixty-one secondary operations were performed after a foramen magnum decompression. Of these 61 operations, 15 involved spinal pathologies not related to the foramen magnum (spinal group), while 46 operations were required for a foramen magnum issue (foramen magnum group). Except for occipital pain and swallowing disturbances, the clinical course was comparable in both groups. In the spinal group, 5 syrinx shunt catheters were removed because of nerve root irritations or spinal cord tethering. Eight patients underwent a total of 10 operations on their cervical spine for radiculopathies or a myelopathy. No permanent surgical morbidity occurred in this group. In the foramen magnum group, 1 patient required a ventriculoperitoneal shunt for hydrocephalus 7 months after decompression. The remaining 45 secondary interventions were foramen magnum revisions, of which 10 were combined with craniocervical fusion. Intraoperatively, arachnoid scarring with obstruction of the foramen of Magendie was the most common finding. Complication rates for foramen magnum revisions were similar to first decompressions, whereas permanent surgical morbidity was higher at 8.9%. Postoperative clinical improvements were marginal in both surgical groups. With the exception of 1 patient who underwent syrinx catheter removal and had a history of postoperative meningitis, all patients in the spinal group were able to be stabilized neurologically. Long-term results in the foramen magnum group revealed clinical stabilizations in 66% for at least 5 years.

CONCLUSIONS

Neurological deterioration in patients after a foramen magnum decompression for CM-I may be related to new spinal pathologies, craniocervical instability, or recurrent CSF flow obstruction at the foramen magnum. Whereas surgery for spinal pathologies is regularly followed by clinical stabilization, the rate of long-term success for foramen magnum revisions was limited to 66% for 5 years due to severe arachnoid scarring in a significant proportion of these patients. Therefore, foramen magnum revisions should be restricted to patients with progressive symptoms.

Treatment of Syringomyelia Related to Nontraumatic Arachnoid Pathologies of the Spinal Canal

BACKGROUND:

Disturbances of cerebrospinal fluid (CSF) flow are the commonest cause of syringomyelia. Spinal arachnopathies may lead to CSF flow obstructions but are difficult to diagnose. Consequently, associated syringomyelias are often categorized as idiopathic.

OBJECTIVE:

To present and analyze the diagnosis of and long-term outcomes in an observational study of patients with nontraumatic arachnopathies from 1991 to 2011.

METHODS:

A total of 288 patients (mean age, 47 ± 15 years; follow-up, 54 ± 46 months) were evaluated. Decompression with arachnolysis, untethering, and duraplasty for restoration of CSF flow was recommended to patients with neurological progression. Neurological examinations, magnetic resonance images, and follow-up data were evaluated. Individual symptoms were analyzed during the first postoperative year, and long-term outcomes were analyzed with Kaplan-Meier statistics to determine rates of progression-free survival.

RESULTS:

In total,189 patients either refused an operation or were managed conservatively for lack of progression. Among 79 unoperated patients with follow-up information available for up to 8 years, 2 patients deteriorated. Ninety-nine patients with progressive symptoms underwent 116 operations: 108 decompressions and 8 other surgeries. Three months postoperatively, 53% considered their status improved and 37% were unchanged. In the long term, surgery on arachnopathies limited to 2 spinal segments was followed by progression-free survival for 78% over 10 years, in contrast to 31% with extensive arachnopathies.

CONCLUSION:

Surgery on nontraumatic arachnopathies related to syringomyelia should be reserved for patients with progressive symptoms. Arachnolysis, untethering, and duraplasty provide good long-term results for focal arachnopathies. For extensive pathologies with a history of subarachnoid hemorrhage or meningitis, treatment remains a major challenge.

Pathophysiology of primary spinal syringomyelia

OBJECT

The pathogenesis of syringomyelia in patients with an associated spinal lesion is incompletely understood. The authors hypothesized that in primary spinal syringomyelia, a subarachnoid block effectively shortens the length of the spinal subarachnoid space (SAS), reducing compliance and the ability of the spinal theca to dampen the subarachnoid CSF pressure waves produced by brain expansion during cardiac systole. This creates exaggerated spinal subarachnoid pressure waves during every heartbeat that act on the spinal cord above the block to drive CSF into the spinal cord and create a syrinx. After a syrinx is formed, enlarged subarachnoid pressure waves compress the external surface of the spinal cord, propel the syrinx fluid, and promote syrinx progression.

METHODS

To elucidate the pathophysiology, the authors prospectively studied 36 adult patients with spinal lesions obstructing the spinal SAS. Testing before surgery included clinical examination; evaluation of anatomy on T1-weighted MRI; measurement of lumbar and cervical subarachnoid mean and pulse pressures at rest, during Valsalva maneuver, during jugular compression, and after removal of CSF (CSF compliance measurement); and evaluation with CT myelography. During surgery, pressure measurements from the SAS above the level of the lesion and the lumbar intrathecal space below the lesion were obtained, and cardiac-gated ultrasonography was performed. One week after surgery, CT myelography was repeated. Three months after surgery, clinical examination, T1-weighted MRI, and CSF pressure recordings (cervical and lumbar) were repeated. Clinical examination and MRI studies were repeated annually thereafter. Findings in patients were compared with those obtained in a group of 18 healthy individuals who had already undergone T1-weighted MRI, cine MRI, and cervical and lumbar subarachnoid pressure testing.

RESULTS

In syringomyelia patients compared with healthy volunteers, cervical subarachnoid pulse pressure was increased (2.7 ± 1.2 vs 1.6 ± 0.6 mm Hg, respectively; p = 0.004), pressure transmission to the thecal sac below the block was reduced, and spinal CSF compliance was decreased. Intraoperative ultrasonography confirmed that pulse pressure waves compressed the outer surface of the spinal cord superior to regions of obstruction of the subarachnoid space.

CONCLUSIONS

These findings are consistent with the theory that a spinal subarachnoid block increases spinal subarachnoid pulse pressure above the block, producing a pressure differential across the obstructed segment of the SAS, which results in syrinx formation and progression. These findings are similar to the results of the authors' previous studies that examined the pathophysiology of syringomyelia associated with obstruction of the SAS at the foramen magnum in the Chiari Type I malformation and indicate that a common mechanism, rather than different, separate mechanisms, underlies syrinx formation in these two entities. Clinical trial registration no.: NCT00011245.

Post-traumatic deformity: prevention and management

Traumatic spinal column injuries (SCI) can result in devastating deformities that often have long-term impact on the patient's quality of life. These deformities result in pain and occasionally neurological deficits. The deformities affecting adults often differ slightly from those in the pediatric population. In adults, injuries to the spinal column frequently result in a sagittal plane deformity, such as kyphosis or lordosis. However, in children, spinal cord injuries often cause coronal deformities, such as scoliosis. Patients with post-traumatic spinal column deformities may present acutely immediately after the injury, many years after the inciting event, or at any time in-between. Patients with post-traumatic spinal deformity initially complain of pain at the site of the deformity, but with time may complain of pain above or below the deformity as a result of degenerative changes. Any change or worsening of neurological status is a worrisome complaint, and often these patients require surgical intervention. Procedures such as fusions and spinal column osteotomies have shown promising results in treating patients with post-traumatic spinal deformities and have been shown to improve their quality of life.

Syringo-subarachnoid-peritoneal shunt using T-tube for treatment of post-traumatic syringomyelia

Various surgical procedures for the treatment of post-traumatic syringomyelia have been introduced recently, but most surgical strategies have been unreliable. We introduce the concept and technique of a new shunting procedure, syringo-subarachnoid-peritoneal shunt. A 54-year-old patient presented to our hospital with a progressive impairment of motion and position sense on the right side. Sixteen years before this admission, he had been treated by decompressive laminectomy for a burst fracture of L1. On his recent admission, magnetic resonance (MR) imaging studies of the whole spine revealed the presence of a huge syrinx extending from the medulla to the L1 vertebral level. We performed a syringo-subarachnoid-peritoneal shunt, including insertion of a T-tube into the syrinx, subarachnoid space and peritoneal cavity. Clinical manifestations and radiological findings improved after the operation. The syringo-subarachnoid-peritoneal shunt has several advantages. First, fluid can communicate freely between the syrinx, the subarachnoid space, and the peritoneal cavity. Secondly, we can prevent shunt catheter from migrating because dural anchoring of the T-tube is easy. Finally, we can perform shunt revision easily, because only one arm of the T-tube is inserted into the intraspinal syringx cavity. We think that this procedure is the most beneficial method among the various shunting procedures.

Syrinx fluid transport: modeling pressure-wave-induced flux across the spinal pial membrane

Syrinxes are fluid-filled cavities of the spinal cord that characterize syringomyelia, a disease involving neurological damage. Their formation and expansion is poorly understood, which has hindered successful treatment. Syrinx cavities are hydraulically connected with the spinal subarachnoid space (SSS) enveloping the spinal cord via the cord interstitium and the network of perivascular spaces (PVSs), which surround blood vessels penetrating the pial membrane that is adherent to the cord surface. Since the spinal canal supports pressure wave propagation, it has been hypothesized that wave-induced fluid exchange across the pial membrane may play a role in syrinx filling. To investigate this conjecture a pair of one-dimensional (1-d) analytical models were developed from classical elastic tube theory coupled with Darcy's law for either perivascular or interstitial flow. The results show that transpial flux serves as a mechanism for damping pressure waves by alleviating hoop stress in the pial membrane. The timescale ratio over which viscous and inertial forces compete was explicitly determined, which predicts that dilated PVS, SSS flow obstructions, and a stiffer and thicker pial membrane-all associated with syringomyelia-will increase transpial flux and retard wave travel. It was also revealed that the propagation of a pressure wave is aided by a less-permeable pial membrane and, in contrast, by a more-permeable spinal cord. This is the first modeling of the spinal canal to include both pressure-wave propagation along the spinal axis and a pathway for fluid to enter and leave the cord, which provides an analytical foundation from which to approach the full poroelastic problem.

Treatment of posttraumatic syringomyelia

Object

This paper presents results of a prospective study for patients undergoing surgery for posttraumatic syringomyelia between 1991 and 2010.

Methods

A group of 137 patients with posttraumatic syringomyelia were evaluated (mean age 45 ± 13 years, mean follow-up 51 ± 51 months) with pre- and postoperative MRI and clinical examinations presenting in this period and followed prospectively by outpatient visits and questionnaires. Surgery was recommended for symptomatic patients with a progressive course. Short-term results were determined within 3 months of surgery, whereas long-term outcomes in terms of clinical recurrences were studied with Kaplan-Meier statistics.

Results

Three groups were distinguished according to the type of trauma: Group A, patients with spinal trauma but without cord injury (ASIA E, n = 37); Group B, patients with an incomplete cord injury (ASIA C or D, n = 55); and Group C, patients with complete loss of motor function or a complete cord injury (ASIA A or B, n = 45). Overall, 61 patients with progressive symptoms underwent 71 operations. Of these operations, 61 consisted of arachnolysis, untethering, and duraplasty at the trauma level (that is, decompression), while 4 ASIA A patients underwent a cordectomy. The remaining procedures consisted of placement of a thecoperitoneal shunt, 2 opiate pump placements, and 2 anterior and 1 posterior cervical decompression and fusion. Seventy-six patients were not treated surgically due to lack of neurological progression or refusal of an operation. Neurological symptoms remained stable for 10 years in 84% of the patients for whom surgery was not recommended due to lack of neurological progression. In contrast, 60% of those who declined recommended surgery had neurological progression within 5 years. For patients presenting with neurological progression, outcome was better with decompression. Postoperatively, 61% demonstrated a reduction of syrinx size. Although neurological symptoms generally remained unchanged after surgery, 47% of affected patients reported a postoperative improvement of their pain syndrome. After 3 months, 51% considered their postoperative status improved and 41% considered it unchanged. In the long-term, favorable results were obtained for Groups A and C with rates for neurological deterioration of 6% and 14% after 5 years, respectively. In Group B, this rate was considerably higher at 39%, because arachnolysis and untethering to preserve residual cord function could not be fully achieved in all patients. Cordectomy led to neurological improvement and syrinx collapse in all 4 patients.

Conclusions

The technique of decompression with arachnolysis, untethering, and duraplasty at the level of the underlying trauma provides good long-term results for patients with progressive neurological symptoms following ASIA A, B and E injuries. Treatment of patients with posttraumatic syringomyelia after spinal cord injuries with preserved motor functions (ASIA C and D) remains a major challenge. Future studies will have to establish whether thecoperitoneal shunts would be a superior alternative for this subgroup.

Long-term results and complications of the syringopleural shunting for treatment of syringomyelia: a clinical study

BACKGROUND

The use of drains in the treatment of syringomyelia has a simple and immediate appeal. Syringopleural shunting in syringomyelia has produced good short-term results, but limited information is available on long-term effects. We analyzed the complications and long-term outcomes after syringopleural shunting for syringomyelia.

CLINICAL MATERIAL AND METHODS

Fourthy-four patients with large-sized syringomyelia underwent syringopleural shunting because of spinal cord compression between 1992 and 2010 in our clinic. Thirty-two patients had Chiari malformation type I (Group B), and 12 patients were associated with primary parenchymal cavitations (Group A). Their ages ranged from 14 to 71 years. Both craniovertebral decompression and syringopleural shunting were performed on 21 patients, whereas only syringopleural shunting was performed on another 21 patients.

RESULTS

The follow-up period ranged from 1 year to 17 years (mean: 9.1 years). There was no operative mortality. Early postoperative MRI revealed that syringes of 43 patients had collapsed. There were 9 (20.5%) minor complications in 9 patients, including temporary neurological deficits (6), respiratory distress (2) and headache (1). Seven (15.9%) serious complications [permanent neurological deficit (1), shunt migration (2), shunt misplacement (1), spinal instability (1), tethering (1), CSF over drainage (1)] were seen in five patients. Four of them were treated with a secondary operation. Three patients (3/9; 33.3%) who were treated by syringopleural shunt alone (Group B2) required craniovertebral decompression, although the shunt was functional. During long-term follow-up, three patients stabilized, five patients (11.3%) developed a worse neurological condition, and two of these patients died 10 and 7 years after surgery. Of all patients, 88.6% showed significant clinical improvement.

CONCLUSIONS

Although there were complications and failures, syringopleural shunting produced satisfactory results at long-term follow-up.

Syringosubarachnoid shunt as a management for syringohydromyelia in dogs

OBJECTIVE

To evaluate retrospectively the efficacy of syringosubarachnoid shunt for the management of syringohydromyelia/syringomyelia.

METHODS

Eleven dogs diagnosed with syringohydromyelia/syringomyelia by magnetic resonance imaging associated with Chiari-like malformation underwent placement of a syringosubarachnoid shunt at the cervical (nine dogs) or lumbar (two dogs) spinal cord. In one dog, a suboccipital decompression (foramen magnum decompression) was performed 4 months before inserting a syringosubarachnoid shunt. All dogs were evaluated neurologically a few hours after surgery, 2 weeks and 6 months postoperatively. Retrospectively, cases were assigned a preoperative and postoperative pain score.

RESULTS

There were no intra- or peri-operative complications. One dog (9%) was euthanased 5 weeks after surgery. Progressive neurological improvement was observed in nine dogs (81·8%) 2 weeks and 6 months postoperatively. No clinical improvement was seen in another dog (9%). One dog (9%) had replacement of the syringosubarachnoid shunt. Seven dogs (63·6%) were still alive 1 to 4 years (mean, 2·6 years) after surgery.

CLINICAL SIGNIFICANCE

Placement of a syringosubarachnoid shunt in the presence of a sufficiently large syrinx appears to be beneficial in dogs with Chiari-like malformation and associated syringohydromyelia/syringomyelia.

Idiopathic syringomyelia: retrospective case series, comprehensive review, and update on management

Object

A syrinx is a fluid-filled cavity within the spinal cord that can be an incidental finding or it can be accompanied by symptoms of pain and temperature insensitivity. Although it is most commonly associated with Chiari malformation Type I, the advancement of imaging techniques has resulted in more incidental idiopathic syringes that are not associated with Chiari, tumor, trauma, or postinfectious causes. The authors present a comprehensive review and management strategies for the idiopathic variant of syringomyelia.

Methods

The authors retrospectively identified 8 idiopathic cases of syringomyelia at their institution during the last 6 years. A PubMed/Medline literature review yielded an additional 38 articles.

Results

Two of the authors' patients underwent surgical treatment that included a combination of laminectomy, lysis of adhesions, duraplasty, and syrinx fenestration. The remaining 6 patients were treated conservatively and had neurologically stable outcomes. Review of the literature suggests that an etiology-driven approach is essential in the diagnosis and management of syringomyelia, although conservative management suffices for most cases. In particular, it is important to look at disturbances in CSF flow, as well as structural abnormalities including arachnoid webs, cysts, scars, and a diminutive posterior fossa.

Conclusions

The precise etiology for idiopathic syringomyelia (IS) is still unclear, although conceptual advances have been made toward the overall understanding of the pathophysiology of IS. Various theories include the cerebellar piston theory, intramedullary pulse pressure theory, and increased spinal subarachnoid pressure. For most patients with IS, conservative management works well. Continued progression of symptoms, however, could be approached using decompressive strategies such as laminectomy, lysis of adhesions, and craniocervical decompression, depending on the level of pathology. Management for patients with progressive neurological dysfunction and the lack of flow disturbance is unclear, although syringosubarachnoid shunting can be considered.

Focal adhesive arachnoiditis of the spinal cord: Imaging diagnosis and surgical resolution

Background:

Although adhesive arachnoiditis of the spinal cord can cause progressive symptoms associated with syringomyelia or myelomalacia, its surgical resolution based on the imaging diagnosis is not well characterized. This study aims to describe the use of imaging for the diagnosis of focal adhesive arachnoiditis of the spinal cord and its surgical resolution using microsurgical arachnoidolysis.

Materials and Methods:

Four consecutive patients with symptomatic syringomyelia or myelomalacia caused by focal adhesive arachnoiditis underwent microsurgical arachnoidolysis. Comprehensive imaging evaluation using constructive interference in steady-state (CISS) magnetic resonance imaging (MRI) or myelographic MR imaging using true fast imaging with steady-state precession (TrueFISP) sequences was included before surgery to determine the surgical indication.

Results:

In all four patients a focal adhesion was identified at the cervical or thoracic level of the spinal cord, a consequence of infection or trauma. Three patients showed modest or minor improvement in neurological function, and one patient was unchanged after surgery. The syringomyelia or myelomalacia resolved after surgery and no recurrence was noted within the follow-up period, which ranged from 5 months to 30 months.

Conclusions:

MRI diagnosis of focal adhesive arachnoiditis is critical to determine the surgical indication. Microsurgical arachnoidolysis appears to be a straightforward method for stabilizing the progressive symptoms, though the procedure is technically demanding.

Pathogenesis of syringomyelia associated with Chiari type 1 malformation: review of evidences and proposal of a new hypothesis

The exact pathogenesis of syringomyelia associated with Chiari type 1 malformation is unknown, although a number of authors have reported their theories of syrinx formation. The purpose of this review is to understand evidences based on the known theories and to create a new hypothesis of the pathogenesis. We critically review the literatures on clinicopathological, radiological, and clinical features of this disorder. The previously proposed theories mainly focused on the driven mechanisms of the cerebrospinal fluid (CSF) into the spinal cord. They did not fully explain radiological features or effects of surgical treatment such as shunting procedures. Common findings of the syrinx in clinicopathological studies were the communication with the central canal and extracanalicular extension to the posterior gray matter. Most of the magnetic resonance imaging studies demonstrated blockade and alternated CSF dynamics at the foramen magnum, but failed to show direct communication of the syrinx with the CSF spaces. Pressure studies revealed almost identical intrasyrinx pressure to the subarachnoid space and decreased compliance of the spinal CSF space. Recent imaging studies suggest that the extracellular fluid accumulation may play an important role. The review of evidences promotes a new hypothesis of syrinx formation. Decreased absorption mechanisms of the extracellular fluid may underlie the pathogenesis of syringomyelia. Reduced compliance of the posterior spinal veins associated with the decreased compliance of the spinal subarachnoid space will result in disturbed absorption of the extracellular fluid through the intramedullary venous channels and formation of syringomyelia.

Decompressive surgery in a patient with posttraumatic syringomyelia

Posttraumatic syringomyelia may result from a variety of inherent conditions and traumatic events, or from some combination of these. Many hypotheses have arisen to explain this complex disorder, but no consensus has emerged. A 28-year-old man presented with progressive lower extremity weakness, spasticity, and decreased sensation below the T4 dermatome five years after an initial trauma. Magnetic resonance imaging (MRI) revealed a large, multi-septate syrinx cavity extending from C5 to L1, with a retropulsed bony fragment of L2. We performed an L2 corpectomy, L1-L3 interbody fusion using a mesh cage and screw fixation, and a wide decompression and release of the ventral portion of the spinal cord with an operating microscope. The patient showed complete resolution of his neurological symptoms, including the bilateral leg weakness and dysesthesia. Postoperative MRI confirmed the collapse of the syrinx and restoration of subarachnoid cerebrospinal fluid (CSF) flow. These findings indicate a good correlation between syrinx collapse and symptomatic improvement. This case showed that syringomyelia may develop through obstruction of the subarachnoid CSF space by a bony fracture and kyphotic deformity. Ventral decompression of the obstructed subarachnoid space, with restoration of spinal alignment, effectively treated the spinal canal encroachment and post-traumatic syringomyelia.

Syringopleural shunt as a rescue procedure in patients with syringomyelia refractory to restoration of cerebrospinal fluid flow

OBJECTIVE

Syringomyelia should be treated by reconstruction of the subarachnoid space and restoration of cerebrospinal fluid homeostasis. Direct intervention on the syrinx is a difficult choice and should be considered a rescue procedure. Data in the literature examining the various options are scanty, with generally unsatisfying results. We report our experience with shunting of the syrinx into the pleural space.

METHODS

Twenty patients with syringomyelia refractory to cerebrospinal fluid flow restoration underwent a procedure for placement of a syringopleural shunt between 1998 and 2008. Modified Japanese Orthopaedic Association Scale scores and magnetic resonance imaging were available for each patient preoperatively and at the latest follow-up evaluation. A 2-tailed Wilcoxon signed-rank test was used for statistical analysis. Complications related to the operative procedure and to hardware failure were noted.

RESULTS

Nineteen patients were available for follow-up with a mean duration of 37.5 (standard deviation, 31.1) months. The condition of 1 patient deteriorated, 2 remained stable, and the remainder improved. The overall mean improvement on the Modified Japanese Orthopaedic Association Scale was 19.5% (95% confidence interval, 8.5-30.5). The median improvement was 4 points on the 17-point scale. Results were statistically significant (P < 0.001). Follow-up magnetic resonance imaging showed syrinx collapse in 17 cases and marked shrinkage in 2 cases. Except for 1 case of meningitis followed by fatal pulmonary embolism, no significant complications were noted.

CONCLUSION

A syringopleural shunt should, in our view, be the syrinx diversion procedure of choice. More series of institutional experiences with a homogeneous approach would be helpful to verify this recommendation.

Thecal shunt placement for treatment of obstructive primary syringomyelia

OBJECT

The most commonly reported treatment of primary syringomyelia has been laminectomy with duraplasty or direct shunting from the syrinx cavity. Diversion of cerebrospinal fluid (CSF) from the spinal subarachnoid space to peritoneal, atrial, or pleural cavities has been described previously in only a few case reports. Shunting of the CSF from the subarachnoid space rostral to the level of myelographic blockage may reduce the filling force of the syrinx cavity and avoids myelotomy and manipulation of the spinal cord parenchyma. The authors report on 7 patients who underwent thecal shunt placement for primary spinal syringomyelia.

METHODS

This study is a retrospective review of a consecutive series. The authors reviewed the medical records and neuroimaging studies of 7 adult patients with posttraumatic, postsurgical, or postinflammatory syringomyelia treated with thecoperitoneal, thecopleural, or thecoatrial shunt placement at the University of California Los Angeles Medical Center. Myelographic evidence of partial or complete CSF flow obstruction was confirmed in the majority of patients. The mean duration of follow-up was 33 months (range 6-104 months).

RESULTS

Six (86%) of 7 patients showed signs of clinical improvement, whereas 1 remained with stable clinical symptoms. Of the 6 patients with available postoperative imaging, each demonstrated a reduction in syrinx size. Three patients (43%) had > or = 1 complication, including shunt-induced cerebellar tonsillar descent in 1 patient and infections in 2.

CONCLUSIONS

If laminectomy with duraplasty is not possible for the treatment of primary syringomyelia, placement of a thecoperitoneal shunt (or thecal shunt to another extrathecal cavity) should be considered. Although complications occurred in 3 of 7 patients, the complication rate was outweighed by a relatively high symptomatic and imaging improvement rate.