On the Pathogenesis of Syringomyelia: A Review

Upper end of the central canal of the human spinal cord: Quantitative anatomical study and 3D modeling

The upper end of the central canal of the human spinal cord has been repeatedly implicated in the pathogenesis of various diseases, yet its precise normal position in the medulla oblongata and upper cervical spinal cord remains unclear. The purpose of this study is to describe the anatomy of the upper end of the central canal with quantitative measurements and a three-dimensional (3D) model. Seven formalin-embalmed human brainstems were included, and the central canal was identified in serial axial histological sections using epithelial membrane antigen antibody staining. Measurements included the distances between the central canal (CC) and the anterior medullary fissure (AMF) and the posterior medullary sulcus (PMS). The surface and perimeter of the CC and the spinal cord were calculated, and its anterior-posterior and maximum lateral lengths were measured for 3D modeling. The upper end of the CC was identified in six specimens, extending from the apertura canalis centralis (ACC) to its final position in the cervical cord. Positioned on the midline, it reaches its final location approximately 15 mm below the obex. No specimen showed canal dilatation, focal stenosis, or evidence of syringomyelia. At 21 mm under the ACC in the cervical cord, the median distance from the CC to the AMF was 3.14 (2.54-3.15) mm and from the CC to the PMS was 5.19 (4.52-5.43) mm, with a progressive shift from the posterior limit to the anterior third of the cervical spinal cord. The median area of the CC was consistently less than 0.1 mm2. The upper end of the CC originates at the ACC, in the posterior part of the MO, and reaches its normal position in the anterior third of the cervical spinal cord less than 2 cm below the obex. Establishing the normal position of the upper end of this canal is crucial for understanding its possible involvement in cranio-cervical junction pathologies.

Delayed spinal arachnoiditis with syringomyelia following aneurysmal subarachnoid haemorrhage: a case report with patient experience

BACKGROUND AND IMPORTANCE

Syringomyelia, or the formation of fluid-filled cysts within the spinal cord, associated with delayed spinal arachnoiditis is an uncommon complication of aneurysmal subarachnoid haemorrhage. To date, about 18 cases have been reported in medical literature, with just two reported in patients under the age of 35 years.

CLINICAL PRESENTATION

A 27-year-old female patient complained of sudden, severe headaches in the occipital region, nuchal rigidity, and drowsiness when she presented at our institution. A head computed tomography scan revealed intraventricular bleeding in the lateral and fourth ventricles with more extensive haemorrhaging in the frontal horns. A left posterior inferior cerebellar artery (PICA) aneurysm was confirmed via digital subtraction angiogram, and endovascular embolization was done. Two years later, the patient reported intense pain in the lower back along with symptoms suggestive of spinal cord compression. Spinal magnetic resonance imaging (MRI) showed spinal adhesions from C1 to L4, syringomyelia with some vasogenic oedema extending from T3 to T9 level, and a cyst in the lumbar region. Consequently, a right hemilaminectomy was performed along with microsurgical release of arachnoid adhesions and placement of a subdural drain. Radiological and symptomatic improvements were observed. Since then, the patient's clinical condition has remained stable during the past three years of follow-up visits.

CONCLUSIONS

Literature on optimal treatment modalities and patient prognosis is scarce and debated. The time for symptom improvement depends on the level and extent of spinal cord involvement. Rehabilitation may be required for most patients, as complete symptomatic recovery may not be attainable.

A computational fluid dynamics study to assess the impact of coughing on cerebrospinal fluid dynamics in Chiari type 1 malformation

Chiari type 1 malformation is a neurological disorder characterized by an obstruction of the cerebrospinal fluid (CSF) circulation between the brain (intracranial) and spinal cord (spinal) compartments. Actions such as coughing might evoke spinal cord complications in patients with Chiari type 1 malformation, but the underlying mechanisms are not well understood. More insight into the impact of the obstruction on local and overall CSF dynamics can help reveal these mechanisms. Therefore, our previously developed computational fluid dynamics framework was used to establish a subject-specific model of the intracranial and upper spinal CSF space of a healthy control. In this model, we emulated a single cough and introduced porous zones to model a posterior (OBS-1), mild (OBS-2), and severe posterior-anterior (OBS-3) obstruction. OBS-1 and OBS-2 induced minor changes to the overall CSF pressures, while OBS-3 caused significantly larger changes with a decoupling between the intracranial and spinal compartment. Coughing led to a peak in overall CSF pressure. During this peak, pressure differences between the lateral ventricles and the spinal compartment were locally amplified for all degrees of obstruction. These results emphasize the effects of coughing and indicate that severe levels of obstruction lead to distinct changes in intracranial pressure.

Direction-selective Resistance to Cerebrospinal Fluid Flow as the Cause of Syringomyelia

The pathophysiology of syringomyelia remains poorly understood. Two prevailing challenges stand out: the need for a comprehensive understanding of its diverse types and the yet-to-be-explained mechanism of cerebrospinal fluid (CSF) retention in the syrinx despite its higher pressure than that in the adjacent subarachnoid space. Expanding on our previous proposal that direction-selective resistance to subarachnoid CSF flow drives syringomyelia genesis, this study uses a computer model to explore this mechanism further. We developed a computer simulation model to study spinal CSF dynamics, employing a lumped parameter approach with multiple compartments. This model replicated the to-and-fro movement of CSF in the spinal subarachnoid space and within an intraspinal channel. Subsequently, a direction-selective resistance-opposing only the caudal subarachnoid CSF flow-was introduced at a specific location within the subarachnoid space. Following the introduction of the direction-selective resistance, a consistent pressure increase was observed in the intraspinal channel downstream of the resistance. Importantly, this increase in pressure accumulated with every cycle of to-and-fro CSF flow. The accumulation results from the pressure drop across the resistance, and its effect on the spinal cord matrix creates a pumping action in the intraspinal channel. Our findings elucidate the mechanisms underlying our hypothesis that a direction-selective resistance to subarachnoid CSF flow causes syringomyelia. This comprehensively explains the various types of syringomyelia and resolves the puzzle of CSF retention in the syrinx despite a pressure gradient.

An analytic model for the flow induced in syringomyelia cavities

A simple two-dimensional fluid-structure-interaction problem, involving viscous oscillatory flow in a channel separated by an elastic membrane from a fluid-filled slender cavity, is analyzed to shed light on the flow dynamics pertaining to syringomyelia, a neurological disorder characterized by the appearance of a large tubular cavity (syrinx) within the spinal cord. The focus is on configurations in which the velocity induced in the cavity, representing the syrinx, is comparable to that found in the channel, representing the subarachnoid space surrounding the spinal cord, both flows being coupled through a linear elastic equation describing the membrane deformation. An asymptotic analysis for small stroke lengths leads to closed-form expressions for the leading-order oscillatory flow, and also for the stationary flow associated with the first-order corrections, the latter involving a steady distribution of transmembrane pressure. The magnitude of the induced flow is found to depend strongly on the frequency, with the result that for channel flow rates of non-sinusoidal waveform, as those found in the spinal canal, higher harmonics can dominate the sloshing motion in the cavity, in agreement with previous in vivo observations. Under some conditions, the cycle-averaged transmembrane pressure, also showing a marked dependence on the frequency, changes sign on increasing the cavity transverse dimension (i.e. orthogonal to the cord axis), underscoring the importance of cavity size in connection with the underlying hydrodynamics. The analytic results presented here can be instrumental in guiding future numerical investigations, needed to clarify the pathogenesis of syringomyelia cavities.

Three-Dimensional Volumetric Magnetic Resonance Imaging Analysis of Syringomyelia Evolution After Posterior Fossa Decompression for Chiari Malformation Type1

OBJECTIVE

This study aims to introduce a method of three-dimensional (3D) volume magnetic resonance imaging (MRI) measurements to evaluate the evolution of syringomyelia (SM) in adults with Chiari malformation type 1 (CM-1) after posterior fossa decompression (PFD), to provide reproducible and accurate measurements.

METHODS

Radiologic and clinical data were obtained for 28 patients. MRI 3D syrinx volumes were evaluated by 2 observers using Philips Healthcare Tumor Tracking tool.

RESULTS

The mean SM preoperative volume was 9.1 ± 15.3 cm3 versus 4.6 ± 8.7 cm3 postoperatively, corresponding to a volume variation reduced by -50% ± 33.4%. A total of 21 patients (75%) showed >25% reduction in SM volume postoperatively and 25 patients (89.2%) showed good to excellent postoperative clinical outcomes. Very high interobserver and intraobserver agreement was noted for 3D volumetric analysis with Cohen weighted κ coefficients (0.899-0.991). A negative correlation was found between the number of involved metameres and the postoperative SM volume reduction (Pearson correlation coefficient = 0.378; P = 0.047). Patients with better clinical outcomes had fewer syrinx septae (F = 8.830; P = 0.001). Similarly, better syrinx volume reduction was associated with fewer septae (F = 1.554; P = 0.233). A positive relationship was observed between clinical outcomes and postoperative syrinx volume reduction (F = 1.554; P= 0.233), with data similar to the reported literature.

CONCLUSIONS

This study shows that 3D volume measurement of the syrinx cavity on MRI is a reproducible and accurate method to assess the postoperative evolution of SM in CM-1 after PFD. Most patients (75%) showed a reduction of SM volume, with a mean volume decrease of 50%. The reliability is yet to be validated in further larger studies.

The Pathogenesis of Chiari Malformation and Syringomyelia: A Case Report and Systematic Review of Current Theories

We report a case of a 42-year-old female presenting with left axillary pain radiating down the arm and weakness in the ipsilateral hand. Specialist examinations of neurological and musculoskeletal systems were insignificant. Magnetic resonance imaging (MRI) of the whole spine and brain revealed cerebellar tonsillar herniation of 9-10mm indicating a Chiari type 1 malformation and a large tubular T2 high-intensity lesion in the cervical cord, extending from the C2/3-disc level down to C6/C7 as well as a similar but smaller lesion behind the bodies of C7 and T1. Both lesions were consistent with syringomyelia. Surgical intervention was deemed inappropriate, and she was treated with three months of physiotherapy. Regular follow-up for two years showed gradual symptom resolution, syrinx shrinkage, and no further complications arising secondary to Chiari type 1 malformation. Chiari malformation is an anatomical anomaly of the cranio-cervical junction. It is often incidentally found on MRI, but although asymptomatic in the population, complications associated with the condition such as syringomyelia are a common initial presentation. The relationship between Chiari malformation, particularly Chiari type 1 malformation, and syringomyelia is close with the majority of patients often presenting with idiopathic syringomyelia also found to have a Chiari type 1 malformation. Considerable discussion about the pathogenic mechanisms for syringomyelia development in Chiari malformation is recognized and advancing continually.

Hemodynamic and Hydrodynamic Pathophysiology in Chiari Type 1 Malformations: Towards Understanding the Genesis of Syrinx

BACKGROUND

The pathophysiology of this association of type 1 Chiari malformation (CM1) and syrinxes is still unknown. There is an alteration in the dynamics of neurofluids (cerebrospinal fluid, arterial and venous blood) during the cardiac cycle in CM1. Our objective is to quantify CSF or arterial blood or venous blood flow in patients with Chiari syndrome (CS) with and without syrinxes using phase-contrast MRI (PCMRI).

METHODS

We included 28 patients with CM1 (9 with syrinxes, 19 without). Morphological MRI with complementary PCMRI sequences was performed. We analyzed intraventricular CSF, subarachnoid spaces CSF, blood, and tonsillar pulsatility.

RESULTS

There is a highly significant correlation (p < 0.001) between cerebral blood flow, cerebral vascular expansion volume and venous drainage distribution. Venous drainage distribution is significantly inversely correlated with oscillatory CSF volume at the level of the foramen magnum plane [-0.37 (0.04)] and not significantly correlated at the C2C3 level [-0.37 (0.05)] over our entire population. This correlation maintained the same trend in patients with syrinxes [-0.80 (<0.01)] and disappeared in patients without a syrinx [-0.05 (0.81)].

CONCLUSION

The distribution of venous drainage is an important factor in intracranial homeostasis. Impaired venous drainage would lead to greater involvement of the CSF in compensating for arterial blood influx, thus contributing to syrinx genesis.

Hypothesis on the pathophysiology of syringomyelia based on analysis of phase-contrast magnetic resonance imaging of Chiari-I malformation patients

Background: Despite several hypotheses, our understanding of syringomyelia's pathophysiology remains limited. The hypothesis proposed by Oldfield et al. suggests that piston-like movement of the cerebellar tonsils propels the cerebrospinal fluid (CSF) into the syrinx via the spinal perivascular space. However, a significant question remains unanswered: how does the CSF enter and stay in the syrinx, which has a higher pressure than the subarachnoid space. In the current study, we attempted to verify Oldfield's hypothesis using phase-contrast magnetic resonance imaging (MRI) data from patients with syringomyelia. Methods: We analyzed phase-contrast MRI scans of 18 patients with Chiari-I malformation associated with syringomyelia, all of whom underwent foramen magnum decompression, and 21 healthy volunteers. We obtained velocity waveforms for CSF and brain tissue from regions of interest (ROI) set at the various locations. These waveforms were synchronized at the peak timing of downward CSF flow. We compared the preoperative patient data with the control data and also compared the preoperative patient data with the postoperative patient data. Results: The syrinx shrank in 17 (94%) of the patients, and they experienced significant clinical improvement. When comparing pre- and postoperative MRI results, the only significant difference noted was the preoperative elevated velocity of the cerebellar tonsil, which disappeared post-surgery. The CSF velocities in the subarachnoid space were higher in the preoperative patients than in the controls, but they did not significantly differ in the postoperative MRI. The tonsillar velocity in the preoperative MRI was significantly lower than that of the CSF, suggesting that the elevated tonsillar velocity was more of an effect, rather than the cause, of the elevated CSF velocity. Conclusions: Given these findings, a completely new paradigm seems necessary. We, therefore, propose a novel hypothesis: the generative force of syringomyelia may be the direction-selective resistance to CSF flow in the subarachnoid space.

Spontaneous improvement in syringomyelia in a patient with Chiari 1 malformation: illustrative case

BACKGROUND

"Chiari malformation" refers to a spectrum of hindbrain abnormalities characterized by impaired cerebrospinal fluid circulation through the foramen magnum. Syringomyelia is frequently found in patients with Chiari malformation type 1. Although many theories have suggested how cerebrospinal fluid enters and makes the cystic cavity in the spinal cord, the pathogenesis of syringomyelia remains controversial. This report documents a case with spontaneous resolution of syringomyelia followed up by 3-year serial magnetic resonance imaging (MRI). These kinds of cases support a more conservative approach.

OBSERVATIONS

A 59-year-old female presented to the authors' clinic in June 2019 with a history of Chiari malformation type 1. This symptomatic patient has been followed up with serial MRI. When the last MRI was performed in August 2022, compared with previous imaging, resolution of the syringomyelia was recognized.

LESSONS

Because the natural evolution of mildly symptomatic/asymptomatic patients with syringes is unclear, these patients pose a treatment dilemma. Although surgical intervention is a widely accepted therapeutic method, a more conservative approach can be considered in cases with spontaneous resolution. Especially for patients without progressive symptoms, the surgical approach should not be considered as the first step. In view of relapses, follow-up with periodic neurological examinations and radiological imaging is preferrable.

Suppression of TGFβR-Smad3 pathway alleviates the syrinx induced by syringomyelia

BACKGROUND

Syringomyelia is a cerebrospinal fluid (CSF) disorder resulted in separation of pain and temperature, dilation of central canal and formation of syrinx in central canal. It is unclear about mechanisms of the dilation and syrinx formation. We aimed to investigate roles of ependymal cells lining central canal on the dilation, trying to reduce syrinx formation in central canal.

METHODS

We employed 78 Sprague-Dawley (SD) rats totally with syringomyelia to detect the contribution of ependymal cells to the dilation of central canal. Immunofluorescence was used to examine the activation of ependymal cells in 54 syringomyelia rat models. BrdU was used to indicate the proliferation of ependymal cells through intraperitoneal administration in 6 syringomyelia rat models. 18 rats with syringomyelia were injected with SIS3, an inhibitor of TGFβR-Smad3, and rats injected with DMSO  were used as control. Among the 18 rats, 12 rats were used for observation of syrinx following SIS3 or DMSO administration by using magnetic resonance imaging (MRI) on day 14 and day 30 under syringomyelia without decompression. All the data were expressed as mean ± standard deviation (mean ± SD). Differences between groups were compared using the two-tailed Student's t-test or ANOVA. Differences were considered significant when *p < 0.05.

RESULTS

Our study showed the dilation and protrusions of central canal on day 5 and enlargement from day 14 after syringomyelia induction in rats with activation of ependymal cells lining central canal. Moreover, the ependymal cells contributed to protrusion formation possibly through migration along with central canal. Furthermore, suppression of TGFβR-Smad3 which was crucial for migration reversed the size of syrnix in central canal without treatment of decompression, suggesting TGFβR-Smad3 signal might be key for dilation of central canal and formation of syrinx.

CONCLUSIONS

The size of syrinx was decreased after SIS3 administration without decompression. Our study depicted the mechanisms of syrinx formation and suggested TGFβR-Smad3 signal might be key for dilation of central canal and formation of syrinx.

Spontaneous resolution of syringomyelia following pregnancy and parturition in a patient with type I chiari malformation: A case and systematic review

BACKGROUND

Spontaneous resolution of syringomyelia has rarely been reported in the literature. Rarer still are cases wherein this process is associated with pregnancy and parturition. We review theories on syringomyelia development and spontaneous resolution to better understand the role pregnancy and parturition may play in both processes.

METHODS

We present a 30-year-old female with MRI-confirmed spontaneous syrinx regression following caesarean delivery of a full-term pregnancy. We additionally review the literature to identify previously reported cases of spontaneous syrinx regression both independent of and associated with pregnancy.

RESULTS

Including the present case, 39 cases describing spontaneous regression of syringomyelia have been reported in the literature, of which only four are associated with pregnancy and parturition. 75% of all reported cases were associated with type I Chiari malformation, though several disorders of the craniocervical junction and spinal canal were implicated. Complete syrinx regression was achieved in 33.3% of cases and 5% of cases described recurrence of syringomyelia following the spontaneous resolution.

CONCLUSION

Syringomyelia likely develops due to disturbance of the physiologic flow of cerebrospinal fluid around the craniocervical junction and the obex. Several mechanisms including fissuring of the spinal cord parenchyma and reduction of subarachnoid scarring are likely involved in this process. In the setting of pregnancy, additional mechanisms surrounding the increased intraabdominal forces imparted by a growing fetus, Valsalva-like strain experienced during labor, and hemodynamic changes that occur to accommodate gestation are likely implicated. Nevertheless, patients should continue to be monitored periodically for syrinx recurrence.

Dura Management Strategies in the Surgical Treatment of Adult Chiari Type I Malformation: A Retrospective, Multicenter, Population-Based Parallel Cohort Case Series

BACKGROUND

Symptomatic Chiari I malformation is treated with suboccipital decompression and C1 laminectomy. However, whether the dura should be opened (durotomy) or enlarged with a graft (duraplasty) remains unclear.

OBJECTIVE

To compare outcomes in adult Chiari I malformation patients treated with duraplasty, durotomy, or without dural opening ("mini-decompression").

METHODS

A retrospective, multicenter, population-based cohort study was performed of all adult patients surgically treated for a Chiari I malformation at 3 regional neurosurgical centers between 2005 and 2017. Three different dura management strategies were favored by the participating hospitals, with data stratified accordingly. The primary outcome was measured using the Chicago Chiari Outcome Scale (CCOS), dichotomized into favorable (CCOS ≥13) or unfavorable (CCOS ≤12). Propensity score matching was used to adjust for potential confounders in outcome comparisons.

RESULTS

In total, 318 patients were included, of whom 52% were treated with duraplasty, 37% with durotomy, and 11% with mini-decompression. In total, 285 (90%) showed a favorable surgical outcome (CCOS ≥13). Duraplasty was associated with more favorable CCOS and shorter hospital stay compared with durotomy, both in unadjusted (93% vs 84%. P = .018 and 6.0 vs 8.0 days, P < .001) and adjusted analyses (92% vs 84%, P = .044 and 6.0 vs 8.0 days, P < .001). Mini-decompression was excluded from the adjusted analyses because of its small sample size.

CONCLUSION

In this study of adult Chiari I malformation, posterior fossa decompression with duraplasty was associated with more favorable postoperative outcome, as determined by the CCOS, compared with posterior fossa decompression with durotomy alone.

Rapid progression of acute cervical syringomyelia: A case report of delayed complications following spinal cord injury

Context: Post-traumatic syringomyelia treatment usually focuses on restoring normal cerebrospinal fluid (CSF) flow. Herein, the first-reported case of delayed post-traumatic syringomyelia associated with an L2 compression fracture 30 years prior to syringomyelia symptoms that rapidly progressed to the brainstem within 5 months, leading to respiratory and circulatory impairments, is summarized. The improvement in symptoms and significant decrease in size of the syringomyelia/syringobulbia achieved in this patient suggest that the initial treatment of choice in such acute cases should be posterior fossa decompression (PFD). Intradural exploration in order to restore the normal CSF flow at the level of trauma can then be planned in a later time.Findings: A retrospective analysis of clinical manifestations and findings obtained from magnetic resonance (MR) imaging, including pre-operative and post-operative follow-up data acquired 6 months later, provided adequate comparisons of the neurological deficits and syrinx size. Interestingly, serial MR images showed that a cervical syrinx acutely progressed to the brainstem within 5 months. PFD and sectioning of the thick veil completely obstructing the foramen of Magendie resulted in partial resolution of the neurological deficits and syringomyelia regression after surgery.Conclusions: To our knowledge, this is the first case report to summarize the delayed complications of a spinal cord injury and acute syringomyelia progression to the brainstem in a short period. The symptoms were relieved by an emergency PFD, chosen due to the rapid progression of symptoms. An atypical treatment strategy is described for extremely rare cases, but with a good short-term prognosis.

Syrinx reduction due to spontaneous spinal cord tear: demonstration on 3 T MRI and review of the literature

A holocord syringomyelia due to Chiari 1.5 malformation (CM) in a 12-year-old girl was serially imaged with 3 T MRI over 4 years. The serial MRI showed reduction in size of the syrinx, without any surgical intervention or CM improvement, but rather due to spontaneous spinal cord tear. The tear was clearly demonstrated by evidence of flow signal across the tear between syrinx and subarachnoid space at the upper thoracic level. The tear showed spontaneous closure at follow-up. A medullary tear has been described in the adult population as one of the putative causes of spontaneous syringomyelia reduction, but its clear demonstration with modern high-resolution MRI has not been reported in the paediatric population. Moreover, this is the first reported case of syrinx reduction due to spontaneous fissuration in a paediatric patient.

Slosh Simulation in a Computer Model of Canine Syringomyelia

The exact pathogenesis of syringomyelia is unknown. Epidural venous distention during raised intrathoracic pressure (Valsalva) may cause impulsive movement of fluid ("slosh") within the syrinx. Such a slosh mechanism is a proposed cause of syrinx dissection into spinal cord parenchyma resulting in craniocaudal propagation of the cavity. We sought to test the "slosh" hypothesis by epidural excitation of CSF pulse in a computer model of canine syringomyelia. Our previously developed canine syringomyelia computer model was modified to include an epidural pressure pulse. Simulations were run for: cord free of cavities; cord with small syringes at different locations; and cord with a syrinx that was progressively expanding caudally. If small syringes are present, there are peaks of stress at those locations. This effect is most pronounced at the locations at which syringes initially form. When a syrinx is expanding caudally, the peak stress is typically at the caudal end of the syrinx. However, when the syrinx reaches the lumbar region; the stress becomes moderate. The findings support the "slosh" hypothesis, suggesting that small cervical syringes may propagate caudally. However, when the syrinx is large, there is less focal stress, which may explain why a syrinx can rapidly expand but then remain unchanged in shape over years.

Delayed Presentation in Chiari Malformation

INTRODUCTION

Chiari malformations are a group of clinicopathological entities with a variety of clinical presentations, different pathophysiology, and variable outcomes. It has a typical set of clinical presentation. In this study is to observe the different clinical presentations of the patients with Chiari malformation in our population. As the time of initial presentation is delayed that might change the sign and symptoms with which patient initially presents.

MATERIALS AND METHODS

This was a cross-sectional observational study with prospectively collected data of 46 patients with Chiari malformation. The duration of the study is from 2017 to 2020. Patient's data will be compiled and analyzed through Statistical Package for Social Sciences (SPSS) Version 25. Qualitative variables are presented as frequencies and percentages. Quantitative variables are presented as mean ± standard deviation. Effect modifiers are controlled through stratification. The Chi-square test is used for finding association between categorical variables. P ≤ 0.05 is considered as statistically significant.

RESULTS

According to our data 36% of our patients presented with motor weakness which is followed by sensory deficit, however in previous literature headache was the commonest clinical presentation.

CONCLUSION

Clinical presentation in our population differs from other studies and the reason behind this is the delayed presentation of the patient and lack of awareness of disease and ultimately it will alter the outcome of disease and treatment.

Spontaneous syrinx resolution in patient with Chiari I malformation: illustrative case

BACKGROUIND

Chiari malformations include a spectrum of congenital hindbrain herniation syndromes. In patients with the most common subtype, Chiari malformation Type I, 50% to 75% develop a syrinx. The pathogenesis of syringomyelia is not well understood, with multiple theories outlined in the literature. Although the presence of a syrinx in a patient with Chiari malformation is generally accepted as an indication for surgical intervention, there are documented cases of spontaneous resolution that support a more conservative approach to management.

OBSERVATIONS

The authors reported a case of spontaneous resolution of a cervical syrinx in an adult with an unchanged Chiari malformation.

LESSONS

Given the possibility of spontaneous resolution over time, the authors believe a more conservative approach of observation with periodic surveillance, magnetic resonance imaging, and neurological examination should be considered in the management of a patient with a Chiari malformation and associated syringomyelia.

MRI characteristics of syringomyelia associated with foramen magnum arachnoiditis: differentiation from Chiari malformation

BACKGROUND

It is important to distinguish foramen magnum arachnoiditis (FMA) from Chiari malformation (CM) before surgery because the operative strategies for these diseases differ. In the current study, we compared pretreatment magnetic resonance imaging (MRI) of FMA with CM and investigated the MRI findings useful to differentiate between these diseases.

METHODS

We retrospectively reviewed patients with FMA or CM aged ≥ 18 years who underwent surgeries at our institution between 2007 and 2019. The morphologies of the syrinx, neural elements, and posterior cranial fossa were preoperatively evaluated with MRI. We used the receiver operating characteristic (ROC) curve for the fourth ventricle-to-syrinx distance (FVSD).

RESULTS

Ten patients with FMAs and 179 with CMs were included. FVSD in the FMA group was significantly shorter than that in the CM group (7.5 mm [IQR, 2.8-10 mm] in FMA vs. 29.9 mm [IQR, 16.3-52.9 mm] in CM, p < 0.0001). The other MRI findings that showed the height, size, and length of the syrinx; size of the foramen magnum; degree of cerebellar tonsillar descent; shape of the cerebellar tonsil; and dorsal subarachnoid space at the foramen magnum differed significantly between the two groups. The ROC curve analysis showed that patients whose FVSD was less than 11 mm could be diagnosed with FMA with a specificity of 90% and sensitivity of 96%.

CONCLUSIONS

A more cranial syrinx development (FVSD < 11 mm) appears to be the characteristic MRI finding in FMA.

Rapid deterioration of an asymptomatic lumbosacral lipoma due to formation of an extracanalicular syrinx: case report

The authors present the case of a 1-month-old girl with a lumbosacral lipoma who then developed an extracanalicular syrinx and experienced rapid deterioration. The patient's initial MRI study, obtained before she became symptomatic, revealed a spinal lipoma with a syrinx in contact with the lipoma-cord interface. She was initially asymptomatic but developed loss of motor function in the left leg 14 days after MRI. Emergency surgery was performed. Intraoperative findings revealed a swollen spinal cord. Lipomatous tissue on the caudal side of the conus was removed subtotally, and the central canal was opened. Expansion of the syrinx was observed intraoperatively. Postoperatively, the patient's left leg paresis remained. Postoperative MRI revealed rostral and extracanalicular expansion of the syrinx. This is the first report on the rapid deterioration of a conus lipoma due to extracanalicular expansion of a syrinx. Careful follow-up and repeat MRI should be considered for patients with spinal lipomas with syringomyelia, especially when the syrinx is attached to the lipoma-cord interface.

A novel classification and its clinical significance in Chiari I malformation with syringomyelia based on high-resolution MRI

BACKGROUND

The existing classification in Chiari I malformation (CM-I) has limited significance for the selection of surgical methods.

OBJECTIVE

The purpose of this study was to investigate the surgery of CM-I with syringomyelia based on the high-resolution MR imaging (HRMRI) findings.

METHODS

Data from 115 patients were collected and retrospectively analyzed. For those with syringomyelia up to the level of C1, HRMRI was performed and according to the communication status between the fourth ventricle and the syringomyelia, patients can be divided into four types, namely Type A: classic communicating; Type B: partial communicating; Type C: non-communicating; Type D: atrophic. All operations were performed with Foramen magnum and Magendie dredging (FMMD), and all intradural factors that may have induced the obstruction of CSF circulation were recorded. The efficiency of operation on syringomyelia was evaluated by mJOA, imaging findings, and complications in the follow-up periods.

RESULTS

The postoperative follow-up period was from 12 to 24 months, with an average of 14.3 months. At 1 year, the mJOA of 115 patients was significantly higher than that before the operations (before surgery 12.1 ± 2.3 vs. after surgery 14. 2 ± 1.4, P < 0.05). In addition, postoperative re-examination showed that the size of the syringomyelia was reduced or completely resolved in patients of Type A, 100% (2/2); Type B, 81% (9/11); Type C, 84% (81/97); and Type D, 20% (1/5).

CONCLUSIONS

According to our new classification based on HRMRI, FMMD is the key to surgical treatment, especially for Type A and Type B patients.

Cerebrospinal fluid flow on time-spatial labeling inversion pulse images before and after treatment of congenital hydrocephalus in a dog

A 3-month-old male cross-breed dog presented with signs of progressive diffuse brain disease. Noncommunicating congenital hydrocephalus concurrent with cervical syringomyelia was diagnosed on magnetic resonance images. On time-spatial labeling inversion pulse (Time-SLIP) images CSF flow through the mesencephalic aqueduct was poorly defined and there was flow into the syrinx across the craniocervical junction. After percutaneous ventricular drainage and ventriculoperitoneal shunting, CSF flow through the aqueduct was clearly detected and flow into the syrinx disappeared. In addition, CSF flow in the subarachnoid space at the pons and ventral aspect of the cervical subarachnoid space was restored. Signs of neurological dysfunction improved after ventriculoperitoneal shunting and the cerebral parenchyma was increased in thickness on 2-year follow-up computed tomography images. Patterns of CSF flow on Time-SLIP images before and after CSF drainage or ventriculoperitoneal shunting aid in clarifying disease pathogenesis and confirm effects of CSF drainage.

Coexisting Retrocerebellar Arachnoid Cyst and Chiari Type 1 Malformation: 3 Pediatric Cases of Surgical Management Tailored to the Pathogenic Mechanism and Systematic Review of the Literature

INTRODUCTION

Arachnoid cysts are benign cerebrospinal fluid collection within a duplication of arachnoid membrane and, when found in the retrocerebellar site, they may be associated with tonsils herniation. This rare situation of coexisting retrocerebellar arachnoid cyst (AC) and Chiari malformation type 1 (CM-1) have been previously reported in few cases (10 patients) with syringomyelia and hydrocephalus described to be the most relevant issues. The aim of this paper is to describe 3 pediatric cases of this condition with a systematic review of the literature, underlining the importance of surgical management tailored to the pathogenic mechanism.

METHODS

A restrospective analysis of patients treated for coexisting CM-1 and ACs at the authors' institution has been carried out.

RESULTS

A case of a 10-month-old baby with coexisting AC and CM-1 with tri-ventricular hydrocephalus treated with endoscopic third ventriculostomy, a case of a 1-year-old child with a huge retrocerebellar AC and CM-1 treated with a cysto-peritoneal shunt, and a case of a 15-year-old child with retrocerebellar AC causing symptomatic CM-1 treated with C0-C2 decompression, AC fenestration and duraplasty are described. A long-term follow-up is reported.

CONCLUSIONS

Surgical management of coexisting ACs and CM-1 should not aim at the complete resolution of the cyst or of tonsil herniation, especially when pediatric patients are treated. Rather, the purpose of the neurosurgeon should be to understand the underlying pathogenic mechanism, and then restoring both the cerebrospinal fluid flow in the posterior fossa and the dynamic equilibrium between ventricles, cyst, and subarachnoid space.

Abnormalities in spinal cord ultrastructure in a rat model of post-traumatic syringomyelia

BACKGROUND

Syringomyelia is a serious complication of spinal cord trauma, occurring in approximately 28% of spinal cord injuries. Treatment options are limited and often produce unsatisfactory results. Post-traumatic syringomyelia (PTS) is presumably related to abnormalities of cerebrospinal fluid (CSF) and interstitial fluid hydrodynamics, but the exact mechanisms are unknown.

METHODS

Transmission electron microscopy (TEM) was used to investigate in detail the interfaces between fluid and tissue in the spinal cords of healthy Sprague-Dawley rats (n = 3) and in a rat model of PTS (n = 3). PTS was induced by computer-controlled impact (75 kDyn) to the spinal cord between C6 and C8, followed by a subarachnoid injection of kaolin to produce focal arachnoiditis. Control animals received a laminectomy only to C6 and C7 vertebrae. Animals were sacrificed 12 weeks post-surgery, and spinal cords were prepared for TEM. Ultra-thin spinal cord sections at the level of the injury were counterstained for structural anatomy.

RESULTS

Spinal cords from animals with PTS displayed several abnormalities including enlarged perivascular spaces, extracellular edema, cell death and loss of tissue integrity. Additionally, alterations to endothelial tight junctions and an abundance of pinocytotic vesicles, in tissue adjacent to syrinx, suggested perturbations to blood-spinal cord barrier (BSCB) function.

CONCLUSIONS

These findings support the hypothesis that perivascular spaces are important pathways for CSF flow into and out of the spinal cord, but also suggest that fluid may enter the cord through vesicular transport and an altered BSCB.

Management of Chiari I malformations: a paradigm in evolution

PURPOSE

Despite decades of experience and research, the etiology and management of Chiari I malformations (CM-I) continue to raise more questions than answers. Controversy abounds in every aspect of management, including the indications, timing, and type of surgery, as well as clinical and radiographic outcomes. This review aims to outline past experiences, consolidate current evidence, and recommend directions for the future management of the Chiari I malformation.

METHODS

A review of recent literature on the management of CM-I in pediatric patients is presented, along with our experience in managing 1073 patients who were diagnosed with CM-I over the past two decades (1998-2018) at Children's National Medical Center (CNMC) in Washington DC.

RESULTS

The general trend reveals an increase in the diagnosis of CM-I at younger ages with a significant proportion of these being incidental findings (0.5-3.6%) in asymptomatic patients as well as a rise in the number of patients undergoing Chiari posterior fossa decompression surgery (PFD). The type of surgical intervention varies widely. At our institution, 104 (37%) Chiari surgeries were bone-only PFD with/without outer leaf durectomy, whereas 177 (63%) were PFD with duraplasty. We did not find a significant difference in outcomes between the PFD and PFDD groups (p = 0.59). An analysis of failures revealed a significant difference between patients who underwent tonsillar coagulation versus those whose tonsils were not manipulated (p = 0.02).

CONCLUSION

While the optimal surgical intervention continues to remain elusive, there is a shift away from intradural techniques in favor of a simple, extradural approach (including dural delamination) in pediatric patients due to high rates of clinical and radiographic success, along with a lower complication rate. The efficacy, safety, and necessity of tonsillar manipulation continue to be heavily contested, as evidence increasingly supports the efficacy and safety of less tonsillar manipulation, including our own experience.

Watertightness of wound closure in lumbar spine-a comparison of different techniques

BACKGROUND

Since a primary watertight dural suture after incidental durotomies has a failure rate of 5-10%, a watertight closure technique of the overlying layers (fascia, subcutis and skin) is essential. The purpose of this cadaveric study was to find the most watertight closure technique for fascia, subcutis and skin.

METHODS

Different suturing techniques were tested for each layer in a sheep cadaveric model by measuring the leakage pressure. The specimens were mounted on a pressure chamber connected to a manometer and a water tube system. Subsequently, the leakage was over-sewed with a cross stitch and the experiment was repeated.

RESULTS

Cross stitch suturing [median =180 mbar (43; 660)] performed best compared to continuous [median =16 mbar (6; 52)] (P=0.003) but not to single knot [median =118 mbar (21; 387)] (P=1.0) or locking stitch suturing [median =109 mbar (3; 149)] (P=0.93) for fascia closure. Continuous suture [median =9 mbar (3; 14)] resulted in a higher leakage pressure than single knot [median =1 mbar (1; 6)] (P=0.017) for subcutaneous closure. No significant differences were found between intracutaneous, Donati-continuous, single knot and locking stitch for skin closures (P=0.075). However, the Donati-continuous stitch closure resulted in higher pressures in tendency. Over-sewing increased median leakage pressure from 8.0 to 11.0 mbar (P=0.068) and from 4.0 to 13.0 mbar (P=0.042) for single knot and for locking stitch skin closures, respectively.

CONCLUSIONS

Cross stitches for the fascia, continuous suturing technique for the subcutis and Donati-continuous stitch for the skin resulted in the most watertight closure within this experimental setting. If leakage occurs, over-sewing might relevantly improve the watertightness of the wound.

The Chiari I malformation

As with many pathologies, the course of our understanding of the Chiari I malformation (CIM) has developed extensively over time. The early descriptions of the Chiari malformations by Hans Chiari in 1891 opened the door for future classification and research on this topic. However, even over a long timeframe, our understanding of the pathophysiology and, more importantly, treatment, remained in its infancy. As recently as the 1970s, CIM was not discussed in popular neurology textbooks. Syringomyelia is listed as a degenerative disorder with no satisfactory treatment. Radiation therapy was considered an option in treatment, and surgery was thought to play no role. During the last 40 years, equivalent to the duration of a neurosurgical career, our understanding of the pathophysiology and natural history of CIM, coupled with modern MRI, has improved the treatment paradigm for this patient population. More importantly, it has given us evidence confirming that CIM is a disorder responsive to surgical intervention, giving patients once thought to be destined for lifelong disability a comparatively normal life after treatment. The purpose of this article is to offer a review of CIM and its important associated entities. The authors will discuss the evolution in understanding of the Chiari malformation and, importantly, distinguish between symptomatic CIM and asymptomatic tonsillar ectopia, based on imaging and presenting symptomatology. They will discuss techniques for surgical intervention, expected outcomes, and complications after surgery. Proper patient selection for surgery based on appropriate symptomatology is tantamount to achieving good surgical outcomes in this population, separating those who can be helped by surgery from those who are unlikely to improve. While our knowledge of the Chiari malformations continues to improve through the efforts of clinical and basic science researchers, surgeons, and patients, our current understanding of these entities represents a monumental improvement in patient care over a relatively short time period.

Adult Klippel-Feil Syndrome: Haemodynamic Instability in the Prone Position and Postoperative Respiratory Failure

A 52-year-old patient with Klippel-Feil syndrome was scheduled for elective C1 dorsal laminectomy and occipitocervical stabilisation under general anaesthesia. Preoperatively she had bulbar symptoms and a history of recurrent aspiration pneumonia, but no evidence of cardiovascular disease. When she was turned prone she developed persistent tachycardia, hypotension and ST segment changes despite fluids, pressors and inotropes. Her condition improved when turned supine, but she had persistent ECG changes and a troponin rise was measured the following day. She was extubated two days postoperatively but aspirated again and subsequently died 12 days later from respiratory failure. If prone positioning is required in patients with Klippel-Feil syndrome we suggest meticulous positioning to avoid sternal compression of the heart. We also suggest thorough preoperative respiratory evaluation and elective postoperative intensive care as these patients are at high risk of developing postoperative respiratory failure.

Dural Laceration Resulting in the Formation of Syringomyelia Caused by a Loosened Hydroxyapatite Intraspinous Spacer after Spinous Process-splitting Laminoplasty

A 63-year-old man was admitted in our hospital with the chief complaint of upper limb numbness 3 years after undergoing spinous process-splitting laminoplasty (C3–C7) in another hospital. The hydroxyapatite spacers used for the laminoplasty had dislocated, resulting sensory disorders of the upper extremities. Additionally, loosened hydroxyapatite intraspinous spacers and syringomyelia were confirmed. A revision operation was performed, during which the C5 spacer was observed to have dislodged into the spinal canal, and a dural membrane defect, arachnoid membrane tear, cerebrospinal fluid leakage, and marked adhesion change were observed. The adhesion was exfoliated as far as possible; moreover, to prevent the reflux of syringomyelia, a syrinx-subarachnoid shunt (SS shunt) was placed. Although there was concern of further adhesion by putting foreign matter, SS shunt indwelling was chosen to obtain sure disappearance of syringomyelia. The postoperative course was uneventful. A gradual improvement in the upper limb numbness was observed without a recurrence of syringomyelia at 9 years of follow-up.

A Computational Model for the Dynamics of Cerebrospinal Fluid in the Spinal Subarachnoid Space

Global models for the dynamics of coupled fluid compartments of the central nervous system (CNS) require simplified representations of the individual components which are both accurate and computationally efficient. This paper presents a one-dimensional model for computing the flow of cerebrospinal fluid (CSF) within the spinal subarachnoid space (SSAS) under the simplifying assumption that it consists of two coaxial tubes representing the spinal cord and the dura. A rigorous analysis of the first-order nonlinear system demonstrates that the system is elliptic-hyperbolic, and hence ill-posed, for some values of parameters, being hyperbolic otherwise. In addition, the system cannot be written in conservation-law form, and thus, an appropriate numerical approach is required, namely the path conservative approach. The designed computational algorithm is shown to be second-order accurate in both space and time, capable of handling strongly nonlinear discontinuities, and a method of coupling it with an unsteady inflow condition is presented. Such an approach is sufficiently rapid to be integrated into a global, closed-loop model for computing the dynamics of coupled fluid compartments of the CNS.

Spinal neuraxial anaesthesia for caesarean section in a parturient with type I Arnold Chiari malformation and syringomyelia

Introduction

Type 1 Arnold Chiari malformation is associated with prolapse of the cerebellar tonsils into or below the level of the foramen magnum and is usually diagnosed in adults. There are no current guidelines for the management of patients with a residual type I Arnold Chiari malformation, planned for a caesarean section under spinal neuraxial anaesthesia. The paucity in the literature on this topic presents as a management dilemma.

Case report

We report a case of a term parturient with type 1 Arnold Chiari malformation, following surgical decompression 4 years earlier, with a residual syringomyelia that underwent an elective caesarean section under spinal neuraxial anaesthesia.

Conclusion

This case highlights that multidisciplinary management and early anaesthetic consult are of paramount importance in the outcome of the patient, and that spinal neuraxial anaesthesia can be considered as a safe anaesthetic option.

Relationship between Cough-Associated Changes in CSF Flow and Disease Severity in Chiari I Malformation: An Exploratory Study Using Real-Time MRI

BACKGROUND AND PURPOSE

Currently no quantitative objective test exists to determine disease severity in a patient with Chiari I malformation. Our aim was to correlate disease severity in symptomatic patients with Chiari I malformation with cough-associated changes in CSF flow as measured with real-time MR imaging.

MATERIALS AND METHODS

Thirteen symptomatic patients with Chiari I malformation (tonsillar herniation of ≥5 mm) were prospectively studied. A real-time, flow-sensitized pencil-beam MR imaging scan was used to measure CSF stroke volume during rest and immediately following coughing and relaxation periods (total scan time, 90 seconds). Multiple posterior fossa and craniocervical anatomic measurements were also obtained. Patients were classified into 2 groups by neurosurgeons blinded to MR imaging measurements: 1) nonspecific Chiari I malformation (5/13)-Chiari I malformation with nonspecific symptoms like non-cough-related or mild occasional cough-related headache, neck pain, dizziness, paresthesias, and/or trouble swallowing; 2) specific Chiari I malformation (8/13)-patients with Chiari I malformation with specific symptoms and/or objective findings like severe cough-related headache, myelopathy, syringomyelia, and muscle atrophy. The Spearman correlation was used to determine correlations between MR imaging measurements and disease severity, and both groups were also compared using a Mann-Whitney U test.

RESULTS

There was a significant negative correlation between the percentage change in CSF stroke volume (resting to postcoughing) and Chiari I malformation disease severity (R = 0.59; P = .03). Mann-Whitney comparisons showed the percentage change in CSF stroke volume (resting to postcoughing) to be significantly different between patient groups (P = .04). No other CSF flow measurement or anatomic measure was significantly different between the groups.

CONCLUSIONS

Our exploratory study suggests that assessment of CSF flow response to a coughing challenge has the potential to become a valuable objective noninvasive test for clinical assessment of disease severity in patients with Chiari I malformation.

Thoracic ossification of ligamentum flavum manifesting holocord syringomyelia: case report

It has been reported that syringomyelia is rarely associated with degenerative spinal disorders, but the case of holocord syringomyelia is never reported. We here present a case of a 59-year-old woman with right shoulder pain, dysesthesia of the right hand, and gait disturbance. Radiographically, examinations of the spine demonstrated holocord syringomyelia with ossification of ligamentum flavum at T2/3 level. Holocord syringomyelia was reduced remarkably after posterior decompression at the T2/3 level, and her symptoms also improved. We speculated that holocord syringomyelia might have developed due to craniospinal pressure dissociation caused by focal compression of dural sac from extradural degenerative change.

Computer simulation of syringomyelia in dogs

Background

Syringomyelia is a pathological condition in which fluid-filled cavities (syringes) form and expand in the spinal cord. Syringomyelia is often linked with obstruction of the craniocervical junction and a Chiari malformation, which is similar in both humans and animals. Some brachycephalic toy breed dogs such as Cavalier King Charles Spaniels (CKCS) are particularly predisposed. The exact mechanism of the formation of syringomyelia is undetermined and consequently with the lack of clinical explanation, engineers and mathematicians have resorted to computer models to identify possible physical mechanisms that can lead to syringes. We developed a computer model of the spinal cavity of a CKCS suffering from a large syrinx. The model was excited at the cranial end to simulate the movement of the cerebrospinal fluid (CSF) and the spinal cord due to the shift of blood volume in the cranium related to the cardiac cycle. To simulate the normal condition, the movement was prescribed to the CSF. To simulate the pathological condition, the movement of CSF was blocked.

Results

For normal conditions the pressure in the SAS was approximately 400 Pa and the same applied to all stress components in the spinal cord. The stress was uniformly distributed along the length of the spinal cord. When the blockage between the cranial and spinal CSF spaces forced the cord to move with the cardiac cycle, shear and axial normal stresses in the cord increased significantly. The sites where the elevated stress was most pronounced coincided with the axial locations where the syringes typically form, but they were at the perimeter rather than in the central portion of the cord. This elevated stress originated from the bending of the cord at the locations where its curvature was high.

Conclusions

The results suggest that it is possible that repetitive stressing of the spinal cord caused by its exaggerated movement could be a cause for the formation of initial syringes. Further consideration of factors such as cord tethering and the difference in mechanical properties of white and grey matter is needed to fully explore this possibility.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1410-7) contains supplementary material, which is available to authorized users.

Embryology and pathophysiology of the Chiari I and II malformations: A comprehensive review

Although the Chiari malformations are well-studied and described developmental anomalies, there remains some incongruity in regards to their underlying etiologies. A number of theories have been proposed with the purpose of accounting for the embryology and pathogenesis of the Chiari I and II malformations and their associated complications and clinical syndromes. The present review aims to review the pertinent literature for all of the main theories that have been proposed, and outline their validity and relevance to our contemporary understanding of these anomalies. Clin. Anat. 31:202-215, 2018. © 2017 Wiley Periodicals, Inc.

A Poroelastic Fluid/Structure-Interaction Model of Cerebrospinal Fluid Dynamics in the Cord With Syringomyelia and Adjacent Subarachnoid-Space Stenosis

An existing axisymmetric fluid/structure-interaction (FSI) model of the spinal cord, pia mater, subarachnoid space, and dura mater in the presence of syringomyelia and subarachnoid-space stenosis was modified to include porous solids. This allowed investigation of a hypothesis for syrinx fluid ingress from cerebrospinal fluid (CSF). Gross model deformation was unchanged by the addition of porosity, but pressure oscillated more in the syrinx and the subarachnoid space below the stenosis. The poroelastic model still exhibited elevated mean pressure in the subarachnoid space below the stenosis and in the syrinx. With realistic cord permeability, there was slight oscillatory shunt flow bypassing the stenosis via the porous tissue over the syrinx. Weak steady streaming flow occurred in a circuit involving craniocaudal flow through the stenosis and back via the syrinx. Mean syrinx volume was scarcely altered when the adjacent stenosis bisected the syrinx, but increased slightly when the syrinx was predominantly located caudal to the stenosis. The fluid content of the tissues over the syrinx oscillated, absorbing most of the radial flow seeping from the subarachnoid space so that it did not reach the syrinx. To a lesser extent, this cyclic swelling in a boundary layer of cord tissue just below the pia occurred all along the cord, representing a mechanism for exchange of interstitial fluid (ISF) and cerebrospinal fluid which could explain recent tracer findings without invoking perivascular conduits. The model demonstrates that syrinx volume increase is possible when there is subarachnoid-space stenosis and the cord and pia are permeable.

Pediatric Chiari malformation type I: long-term outcomes following small-bone-window posterior fossa decompression with autologous-fascia duraplasty

Chiari malformation type I (CM-I) is a common hindbrain disorder that is associated with deformity and elongation of the cerebellar tonsils. Although CM-I occurs in both pediatric and adult patients, its prevalence, clinical features and management in the pediatric population are not well defined. The current study evaluated a consecutive case series of 92 children (38 females and 54 males) who were diagnosed with congenital CM-I. All patients underwent small-bone-window posterior fossa decompression with autologous-fascia duraplasty. Clinical and radiological features were analyzed and long-term follow-up data were recorded. Risk factors associated with clinical outcomes were investigated using comprehensive statistical methods. Out of the 92 children, 11 (12.0%) were asymptomatic. Associated ventricular dilation was observed in 24 children (26.1%) and concomitant syringomyelia was observed in 72 children (78.3%). A total of 44 children (47.8%) showed scoliosis on plain films. Follow-up data (mean duration, 88.6 months) were available for all patients. Syringomyelia was absent or markedly reduced in 56 patients (77.8%). Symptoms were alleviated in 66 patients, remained unchanged in 12 patients and progressed in 3 patients. Statistical analysis indicated that the cerebellar tonsillar descent (CTD) grade, basilar invagination and platybasia influenced the clinical outcome (P<0.05). In conclusion, early recognition and surgical treatment of CM-I in pediatric patients can lead to good outcomes. The current results suggested that small-bone-window posterior fossa decompression with autologous-fascia duraplasty was an effective safe treatment option with a low complication rate. High CTD grade, basilar invagination and platybasia were indicated to be predictors of poor clinical prognosis.

Characteristics of CSF Velocity-Time Profile in Posttraumatic Syringomyelia

BACKGROUND AND PURPOSE

The development of syringomyelia has been associated with changes in CSF flow dynamics in the spinal subarachnoid space. However, differences in CSF flow velocity between patients with posttraumatic syringomyelia and healthy participants remains unclear. The aim of this work was to define differences in CSF flow above and below a syrinx in participants with posttraumatic syringomyelia and compare the CSF flow with that in healthy controls.

MATERIALS AND METHODS

Six participants with posttraumatic syringomyelia were recruited for this study. Phase-contrast MR imaging was used to measure CSF flow velocity at the base of the skull and above and below the syrinx. Velocity magnitudes and temporal features of the CSF velocity profile were compared with those in healthy controls.

RESULTS

CSF flow velocity in the spinal subarachnoid space of participants with syringomyelia was similar at different locations despite differences in syrinx size and locations. Peak cranial and caudal velocities above and below the syrinx were not significantly different (peak cranial velocity, P = .9; peak caudal velocity, P = 1.0), but the peak velocities were significantly lower (P < .001, P = .007) in the participants with syringomyelia compared with matched controls. Most notably, the duration of caudal flow was significantly shorter (P = .003) in the participants with syringomyelia.

CONCLUSIONS

CSF flow within the posttraumatic syringomyelia group was relatively uniform along the spinal canal, but there are differences in the timing of CSF flow compared with that in matched healthy controls. This finding supports the hypothesis that syrinx development may be associated with temporal changes in spinal CSF flow.

Syringomyelia Fluid Dynamics and Cord Motion Revealed by Serendipitous Null Point Artifacts during Cine MRI

Dynamic MR imaging was used to evaluate a cervical syrinx in an adolescent boy with an associated hindbrain herniation. Null artifacts were present on one of the sequences that allowed simultaneous high-resolution visualization of syrinx fluid motion and the anatomy of the syrinx walls. A brief review of the theories of syrinx formation and propagation is provided with a comment on why the Williams "slosh" theory of syrinx progression is supported by our unique imaging.

Visualization of cerebrospinal fluid flow in syringomyelia through noninvasive magnetic resonance imaging with a time-spatial labeling inversion pulse (Time-SLIP)

CONTEXT

We report a case of syringomyelia assessed by magnetic resonance imaging (MRI) with a time-spatial labeling inversion pulse (Time-SLIP), which is a non-contrast MRI technique that uses the cerebrospinal fluid (CSF) as an intrinsic tracer, thus removing the need to administer a contrast agent. Time-SLIP permits investigation of flow movement for over 3 seconds without any limitations associated with the cardiac phase, and it is a clinically accessible method for flow analysis.

FINDINGS

We investigated an 85-year-old male experiencing progressive gait disturbance, with leg numbness and muscle weakness. Conventional MRI revealed syringomyelia from C7 to T12, with multiple webs of cavities. We then applied the Time-SLIP approach to characterize CSF flow in the syringomyelic cavities. Time-SLIP detected several unique CSF flow patterns that could not be observed by conventional imaging. The basic CSF flow pattern in the subarachnoid space was pulsatile and was harmonious with the heartbeat. Several unique flow patterns, such as bubbles, jumping, and fast flow, were observed within syringomyelic cavities by Time-SLIP imaging. These patterns likely reflect the complex flow paths through the septum and/or webs of cavities.

CONCLUSION/CLINICAL RELEVANCE

Time-SLIP permits observation of CSF motion over a long period of time and detects patterns of flow velocity and direction. Thus, this novel approach to CSF flow analysis can be used to gain a more extensive understanding of spinal disease pathology and to optimize surgical access in the treatment of spinal lesions. Additionally, Time-SLIP has broad applicability in the field of spinal research.

Comparison of clinical and radiological manifestations and surgical outcomes of pediatric Chiari I malformations in different age groups

PURPOSE

The aim of this study was to elucidate the differences in clinical and radiological manifestations and treatment outcomes of pediatric Chiari I malformation patients according to age.

METHODS

We retrospectively reviewed the patients who received surgery in our institution for symptomatic Chiari I malformations between January 1991 and December 2012. Fifty-four patients were identified, and their medical records were reviewed for clinical presentation, radiological findings, surgical treatment, and outcomes including complications. We divided the patients into 3 groups: Group I (n = 4) younger than 3 years old; Group II (n = 9) between 3 and 5 years old; and Group III (n = 41) older than 5 years old. Surveyed data were compared among the groups. The mean follow-up period was 82.8 months.

RESULTS

All of Group I patients presented with stem compression signs. Ventriculomegaly was common (3/4, 75%), but no syrinx or scoliosis was observed. In Group II, scoliosis was the most common presentation (5/9, 56%), and these patients rarely complained any other symptoms. Pain, such as headache (18/41, 44%), was the predominant presentation in Group III. The incidences of syrinx and scoliosis were similar in Groups II and III. There were no differences in the treatment outcomes among the groups. The spinal curve did not improve in 4 of 5 Group II patients despite their early FMD surgeries. The incidence of complications related to cerebrospinal fluid leakage was higher in the young age group.

CONCLUSIONS

The clinical and radiological manifestations of pediatric Chiari I malformation appeared to be different according to age.

Intramedullary Spinal Cord Tumors: Part I-Epidemiology, Pathophysiology, and Diagnosis

Study Design Broad narrative review. Objectives Intramedullary spinal cord tumors (IMSCT) are rare neoplasms that can potentially lead to severe neurologic deterioration, decreased function, poor quality of life, or death. As such, a better understanding of these lesions is needed. The following article, part one of a two-part series, addresses IMSCT with regards to their epidemiology, histology, pathophysiology, imaging characteristics, and clinical manifestations. Methods The authors performed an extensive review of the peer-reviewed literature addressing the aforementioned objectives. Results Numerous IMSCT exist with varying epidemiology. Each IMSCT has its own hallmark characteristics and may vary with regards to how aggressively they invade the spinal cord. These lesions are often difficult to detect and are often misdiagnosed. Furthermore, radiographically and clinically, these lesions may be difficult to distinguish from one another. Conclusions Awareness and understanding of IMSCT is imperative to facilitate an early diagnosis and plan management.