Noncommunicating Syringomyelia Research Articles

Outcome predictors and clinical presentation of syringomyelia

The prognosis of syringomyelia is not yet established. Syringomyelia derived from different etiologies contributes to similar symptoms. Assess the syringomyelia in our medical institutes and describe the etiologies and clinical appearance of the disorder. And identify the predictors of a good outcome and to find the most suitable timing of surgical intervention according to our results. This retrospective cohort study used databases in our hospitals to analyze 70 cases of syringomyelia between 1997 and 2014. All available information was obtained from medical records and radiological reports. We used American Spinal Injuries Association disability scores (ASIA scores), the modified Nurick classification system, and recorded the number of days the patient was hospitalized, for neurological and functional assessment. Univariate and multivariate analyses were used to evaluate the relationship between clinical factors and outcomes. Non-communicating syringomyelia was the most common type of syringomyelia. In univariate analysis, autonomic dysfunction and motor impairment were strong predictors of poor neurological and functional outcomes. In addition to the above factors, syrinxes at the cervical level predicted better functional outcomes than at any spinal level in multivariate analysis. Motor impairment, which is commonly seen in patients with syringomyelia in Taiwan, is a strong predictor to poor neurological and functional outcomes. Our study indicates that patients without autonomic dysfunction or motor impairment should receive timely surgical intervention to prevent symptomatic deterioration. We also found that cervical syringomyelia in particular has the potential for good functional recovery after adequate intervention.

Cervical Central Canal Occlusion Induces Noncommunicating Syringomyelia

Mechanisms underlying the development of noncommunicating syringomyelia are poorly understood. To assess the influence of focal arachnoiditis and central canal (CC) occlusion (CCO) on the formation of noncommunicating syringomyelia in the adult rat cervical spinal cord. Expression of pericanalicular aquaporin-4 is also examined. Sprague-Dawley rats were subjected to circumferential or dorsal arachnoiditis (n = 34). Rats undergoing CCO (n = 69) were divided into 4 groups: group A, kaolin injection at a single site in the dorsal columns near the CC; group B, kaolin injection at multiple sites in the dorsal columns near the CC; group C, saline injection at multiple sites in the dorsal columns near the CC; or group D, controls. Rats were killed at 1, 4, 8, and 12 weeks. The CC area and aquaporin-4 (AQP4) expression were measured at the level of maximal CC enlargement. Circumferential and dorsal arachnoiditis induced a mild increase in the CC area at 12 weeks. Single-site CCO induced slight CC enlargement. In contrast, multiple sites of CCO in proximity frequently induced a major expansion of the CC area (up to 50 times). Increased AQP4 expression was observed in pericanalicular astrocytes proportional to the degree of CC expansion. Multiple sites of CCO created a model of noncommunicating syringomyelia in adult rats. Increased astrocytic AQP4 expression was proportional to the degree of CC expansion. Modulation of aquaporin expression may be a novel target for therapeutic interventions to prevent syringomyelia.

Non-communicating syringomyelia: a feature of spinal cord involvement in multiple sclerosis

In patients with multiple sclerosis (MS) non-communicating syringomyelia (NCS) has been described as an incidental finding in case studies and small case series. NCS in MS patients commonly leads to uncertainty particularly as the clinical picture of NCS is variable and surgical therapy may be considered. Up to date little is known about the prevalence and clinical importance of NCS in MS. We report the imaging and clinical characteristics of NCS formations in nine MS patients from a 1 year follow-up study in a representative group of 202 MS (4.5%) patients. Brain and spinal cord MRI was performed as part of a genetic study. NCS did commonly extend the central canal and the cord was slightly distended at the level of the syrinx. The cord and syrinx showed no tendency to change in size or shape over 1 year. Despite thorough search into the clinical history and current clinical status no definite but only minimal indications of symptoms potentially related to the NCS were found. We confirm that NCS may occur in MS patients with spinal cord pathology. It can be a subtle finding without clinical correlates. Syrinx formations are more likely to be a consequence of MS cord pathology than a coincidental finding.

An unusual presentation and resolution of syringomyelia after cervical spine injury

The authors describe a case of noncommunicating syringomyelia associated with Chiari malformation Type I in a patient in whom acute symptomatic exacerbation occurred following cervical spine trauma. Surgical stabilization and realignment of the spine resulted in marked resolution of the neurological abnormalities, and subsequent magnetic resonance imaging demonstrated persistent collapse of the syrinx. The authors review the various factors in the pathogenesis of this unusual sequence of events.

Coexistencia de siringomielia y meningioma intradural extramedular

The coexistence of non-communicating syringomyelia with extramedullary intradural tumours in surgical series is extremely rare. We report the case of a 68-year-old female who had been suffering from predominantly proximal asymmetrical progressive paraparesis, with no involvement of the sphincters; the clinical exploration revealed a band of thermal hypaesthesia D7-D8. Magnetic resonance imaging (MRI), following the administration of gadolinium, confirmed the coexistence of an extramedullary intradural expansive lesion, which had features suggesting it could be a meningioma, and a dorsal syringomyelia. The cavity involved two medullary segments situated above the tumour and there were no associated anomalies at the junction of the medulla and upper spinal cord. Following complete resection of the tumour, which was diagnosed histologically as being a transitional meningioma with abundant psammoma bodies, the patient recovered the ability to walk independently. MRI with contrast is the best diagnostic means available for the detection and delimitation of the two components in this rare association, although its capacity to detect signs suggesting turbulences in the intracavity fluid, especially in small cavities, has still to be confirmed. The variations in the size and situation of the cavity with respect to the seat of the tumour, and the fact that progress is seldom monitored with MRI in the cases published to date, do not allow us to identify the pathogenic mechanism responsible for this association or to suggest the best type of shunt to prevent a possible expansion of the syringomyelic cavity.

Application of syringosubarachnoid shunt through key-hole laminectomy

The authors describe the key-hole laminectomy technique (KHLT) for application of syringosubarachnoid shunts. This technique was used in 29 patients with noncommunicating syringomyelia. In all cases the shunts were inserted successfully without any peri- or late postoperative complications. The late follow-up magnetic resonance examinations revealed the clear collapse of syrinx in all cases. The authors advocate use of the KHLT because it is associated with less surgery-related trauma, epidural fibrosis, infection, and spinal instability.

Mechanisms underlying the formation and enlargement of noncommunicating syringomyelia: experimental studies

The pathogenesis of noncommunicating syringomyelia is unknown, and none of the existing theories adequately explains the production of cysts that occur in association with conditions other than Chiari malformation. The authors' hypothesis is that an arterial pulsation-driven perivascular flow of cerebrospinal fluid (CSF) is responsible for syrinx formation and enlargement. They investigated normal CSF flow patterns in 20 rats and five sheep by using the tracer horseradish peroxidase; the effect of reducing arterial pulse pressure was examined in four sheep by partially ligating the brachiocephalic trunk; CSF flow was examined in 78 rats with the intraparenchymal kaolin model of noncommunicating syringomyelia; and extracanalicular cysts were examined using the excitotoxic model in 38 rats. In the normal animals there was a rapid flow of CSF from the spinal subarachnoid space into the spinal cord perivascular spaces and then into the central canal. This flow ceased when arterial pulsations were diminished. In animals with noncommunicating syringomyelia, there was rapid CSF flow into isolated and enlarged segments of central canal, even when these cysts were causing pressure damage to the surrounding spinal cord. Exitotoxic injury of the spinal cord caused the formation of extracanalicular cysts, and larger cysts were produced when this injury was combined with arachnoiditis, which impaired subarachnoid CSF flow. The results of these experiments support the hypothesis that arterial pulsation-driven perivascular fluid flow is responsible for syrinx formation and enlargement.

Cerebrospinal fluid flow in an animal model of noncommunicating syringomyelia.

The source of fluid and the mechanism of cyst enlargement in syringomyelia are unknown. It has been demonstrated that cerebrospinal fluid (CSF) normally flows from the subarachnoid space through perivascular spaces and into the spinal cord central canal. The aim of this study was to investigate whether this flow continues during cyst formation in an animal model of syringomyelia and to determine the role of subarachnoid CSF flow in this model. The intraparenchymal kaolin model of noncommunicating syringomyelia was established in 78 Sprague-Dawley rats. Horseradish peroxidase was used as a tracer to study CSF flow at 1 day, 3 days, 1 week, and 6 weeks after kaolin injection. CSF flow was studied at 0, 10, and 30 minutes after horseradish peroxidase injection into the cisterna magna or thoracic subarachnoid space. The central canal became occluded at the level of the kaolin injection and at one or more rostral levels. Segments of the central canal isolated between occlusions gradually dilated, and axonal retraction balls were detected in the surrounding white matter. There was a partial blockage of subarachnoid CSF flow at the site of the kaolin injection, both in a rostral-caudal direction and in a caudal-rostral direction. Horseradish peroxidase was detected at all time points, in a distinctive pattern, in perivascular spaces and the central canal. This pattern was seen even where segments of the central canal were isolated and dilated. In this animal model, noncommunicating syringes continue to enlarge even when there is evidence that they are under high pressure. There may be an increase in pulse pressure rostral to the block of subarachnoid CSF flow, causing an increase in perivascular flow and contributing to syrinx formation. The source of fluid in noncommunicating syringomyelia may be arterial pulsation-dependent CSF flow from perivascular spaces into the central canal.

Evidence for rapid fluid flow from the subarachnoid space into the spinal cord central canal in the rat

Horseradish peroxidase (HRP) was used as a CSF tracer in Sprague-Dawley rats. One group of rats received an injection of HRP in the cistema magna and a second group was injected in the thoracic spinal subarachnoid space. The animals were sacrificed 0, 10 or 30 min after HRP injection by rapid perfusion with paraformaldehyde and glutaraldehyde. In both groups, there was rapid HRP labeling of brain and spinal cord perivascular spaces. HRP was present in the central canal in a pattern that was not consistent with flow from the fourth ventricle: in both groups there were segments of unlabeled central canal between the fourth ventricle and central canal segments containing HRP. HRP-labeled perivascular spaces were seen in the central gray matter adjacent to the central canal. There was a distinctive pattern of interstitial HRP between perivascular spaces and the central canal. The results suggest that there is a normal flow of fluid from the subarachnoid space, into the perivascular spaces, across the interstitial space and into the central canal. The function of this flow may be to clear metabolites from the interstitial space. The existence of such a flow would add considerable support to the theory that non-communicating syringomyelia develops in segments of central canal isolated by occlusion or stenosis at each end.

Syringomyelia After Removal of Benign Spinal Extramedullary Neoplasms

This is a case report. Two patients with noncommunicating syringomyelia manifesting symptoms years after the uneventful excision of a benign intradural extramedullary neoplasms are presented. The association of noncommunicating syringomyelia with benign extramedullary neoplasms as a coexistent or delayed process is a rare event. The pathogenesis of such spinal cord cavitation after tumor removal and the relationship with therapeutic intervention is not well defined. The delayed occurrence of neurologic impairment emphasizes the need for considering development of syringomyelia rather than tumor recurrence. The effects of chronic spinal cord compression in the thoracic region may be accelerated by adverse stresses acting on the spinal cord associated with tethering of the spinal cord. In defining the pathogenesis of this form of spinal cord cavitation, these cases suggest that therapeutic approaches directed at resolving the process should not only include lyses of adhesions, but shunting procedures, which appear to be most efficacious when these procedures are performed at or cephalad to the level of original tumor removal.

Experimental syringomyelia in the rabbit: an ultrastructural study of the spinal cord tissue.

Hydrosyringomyelia was produced experimentally by the injection of kaolin into the cisterna magna of the rabbit, and the ultrastructural changes of the spinal cord surrounding the syrinx were investigated 2, 4, and 6 weeks after injection by transmission electron microscopy. The ependyma at the ventral part of the central canal was flat and stretched, whereas, in the dorsal part, it was split, and the syrinx extended through the dorsal median plane in most animals. Extracellular edema was found in the subependymal white matter and in and around the posterior median septum. Many nerve fibers surrounding the syrinx were in varying stages of axonal degeneration. Myelin sheaths were split, thinned, and completely lost in many nerve fibers. In some fibers, the axons were totally lost, leaving the myelin sheaths as empty tubes. Astrocytic processes containing a large number of glial filaments covered the nerve fibers adjacent to the syrinx and partially replaced the edematous area. The perivascular spaces were enlarged, especially near the syrinx and in the dorsal white matter. Oligodendrocytes remained undamaged, and the remyelination by oligodendrocytic processes was seen on some denuded axons. Sometimes, this further remyelination was abortive, especially where the edema was severe. The ultrastructural changes of the neural tissue and their sequences were identical, in most respects, to those of hydrocephalus and noncommunicating syringomyelia. The oligodendrocytic remyelination with ongoing demyelination found in this model has many similarities to those in experimental hydrocephalus.

Noncommunicating syringomyelia following occlusion of central canal in rats. Experimental model and histological findings.

This report describes a new and reliable technique for producing experimental noncommunicating syringomyelia. In 30 rats, 1.2 to 1.6 microliters of kaolin was microinjected into the dorsal columns and central gray matter of the spinal cord at C-6. The inoculations caused transient neurological deficits in four animals and no deficits in 26 animals. Within 24 hours, kaolin and polymorphonuclear leukocytes entered the central canal and drained rostrally. The clearance of inflammatory products induced a proliferation of ependymal cells and periependymal fibrous astrocytes, which formed synechiae and obstructed the canal at the level of injection and at one or more levels up to C-1. In 22 animals followed for 48 hours or longer, the upper end of the central canal became acutely dilated and formed an ependyma-lined syrinx that enlarged to massive dimensions within 6 weeks. The rostral syrinxes did not communicate with the fourth ventricle and were not associated with hydrocephalus. The histological findings in acute noncommunicating syringomyelia were characterized by progressive stretching and thinning of the ependyma, elongation of intracanalicular septae, and the formation of periependymal edema. After 3 weeks, there was progressive compression of the periependymal tissues associated with stretching of axons, fragmentation of myelin sheaths, and the formation of myelin droplets. These findings and the sequence in which they evolved were identical in most respects to those occurring in acute and subacute noncommunicating hydrocephalus.

Noncommunicating syringomyelia in multiple sclerosis

We report 3 patients in whom multiple sclerosis appeared to be complicated by noncommunicating syringomyelia. Despite modest or minimal signs of myelopathy, each patient had cavitary spinal cord lesions detected with MRI. MS may be associated with noncommunicating syringomyelia.