Idiopathic localized hydromyelia: dilatation of the central canal of the spinal cord of probable congenital origin

Characterizing syringomyelia and its clinical significance in 140 patients with lipomyelomeningocele

OBJECTIVE

The aims of this study were to characterize syringomyelia in patients with lipomyelomeningocele (LMMC) and investigate the association between the presence of a syrinx and patient neurological deficits.

METHODS

Patients with LMMC who had been admitted between 2007 and 2020 were included in the study. Syringomyelia on magnetic resonance imaging (MRI) was classified into three groups: true syrinx, early syrinx, and presyrinx. The correlation of clinical deficits (at birth, new onset, and progressive) and type of lipoma with the presence and type of syrinx was studied.

RESULTS

Among a total of 140 patients, the median age was 2.5 (IQR 1.3-9) years. Neurological deficits were present at birth in 75 (53.6%) patients, but 67 (47.9%) had new-onset deficits or progression of their birth deficits. The most common type of spinal lipoma was the transitional type (75.7%). Thirty-nine (27.9%) patients had a syrinx (37 with a true syrinx, 2 with an early syrinx), and 25 (17.9%) patients had a presyrinx. There was no significant correlation between the presence of a syrinx and patient neurological deficits. However, patients with a syrinx that was not adjacent to the lipoma (≥ 1 vertebral level away) had a higher incidence of deficits at birth (p = 0.045), whereas those with a syrinx spanning ≥ 5 vertebral levels had a higher incidence of progressive neurological deficits (p = 0.04). Six (75%) of 8 patients in whom serial MRI had shown syrinx progression had clinical worsening.

CONCLUSIONS

Syrinx location with respect to the spinal lipoma, syrinx length, and progressive syringomyelia may have clinical significance in patients with LMMC.

Spinal cord subependymoma mimicking syringomyelia in a child: a case report

Spinal cord subependymomas (SCSEs) in children are extremely rare, and no reports distinguishing SCSEs from syringomyelia have been published. We report a case of a 10-year-old boy who presented with torticollis, scoliosis, as well as pain that had begun in the posterior portion of the neck and progressed to the right shoulder and upper arm. Magnetic resonance imaging showed an intramedullary cyst-like lesion with the same signal intensity as that of cerebrospinal fluid. Idiopathic syringomyelia with scoliosis was first suspected, and a syrinx-subarachnoid space shunt was performed. After surgery, the lesion was slightly smaller; however, 2 years after surgery, it had re-grown, causing excruciating pain but no other symptoms. A second surgery was performed, and gross total resection was achieved. Pathological evaluation revealed SCSE. SCSE needs to be considered as a differential diagnosis for spinal centric cyst-like lesions in children.

Scoliosis in spinal muscular atrophy: is the preoperative magnetic resonance imaging necessary?

PURPOSE

To determine the prevalence of intraspinal alterations in scoliosis due to Spinal Muscular Atrophy (SMA).

METHODS

Cross-sectional, observational, descriptive study. Fifty-six patients with SMA diagnosis required surgical treatment due to scoliosis.

INCLUSION CRITERIA

scoliosis/kyphoscoliosis > 50 degrees in the coronal plane, clinical characteristics of Spinal Muscular Atrophy, accurate diagnosis by means of molecular or genetic study. Prior to the spinal surgery, and to find related intraspinal alterations, MRI of the spine and posterior cranial fossa was performed.

RESULTS

Forty females, 16 males, mean age 11 years (range 6-14 years). 94% of the patients had Spinal Muscular Atrophy type 2. The mean angle value was 81 degrees (range 53-122 degrees) in the coronal plane and 62 degrees (range 35-80 degrees) in the sagittal plane. The prevalence of intraspinal alterations was 1.78%. One patient with cervical hydromyelia and no neurological surgical procedure prior to the spinal deformity surgery was reported.

CONCLUSIONS

In the context of preoperative planning and strategy of patients with scoliosis due to Spinal Muscular Atrophy, MRI may have not to be requested.

Syringomyelia and hydromyelia: Current understanding and neurosurgical management

Syringomyelia is a rare disorder in which a fluid-filled cyst forms within the spinal cord, resulting in myelopathy. Meanwhile, the abnormal dilatation of the central canal is referred to as hydromyelia or slit-like syrinx. The most prevailing classification is based on anatomical features and pathogeny rather than pathophysiological mechanisms. It is usual to distinguish foraminal syringomyelia related mainly to abnormalities at the craniocervical junction, non-foraminal syringomyelia dealing with any cause of arachnoiditis (infection, inflammation, trauma…) and more rarely syringomyelia associated with intramedullary tumors. Although many pathophysiological theories have been argued over time, the prevailing one is that disturbances in cerebrospinal fluid (CSF) flow in the sub-arachnoid spaces disrupt flow velocity leading to the syrinx. Symptoms of paralysis, sensory loss and chronic pain commonly develop during the third/fourth decades of life. The natural history of syringomyelia is typically one of gradual, stepwise neurological deterioration extending over many years. Diagnosis is based on magnetic resonance imaging (MRI) including excellent morphological sequences (T1-, T2-, FLAIR-, T2*-, enhanced T1-) and dynamic MRI with careful study of CSF velocity (CISS, cine-MR sequences). Surgical management is at first dedicated to treat the cause of the syringomyelia, mainly to re-establish a physiological CSF pathway in the subarachnoid spaces. Mostly, the surgical goal is to enlarge the craniocervical junction with duraplasty. Other surgical strategies such as arachnoidolysis or shunt procedures are performed based on the pathogenic mechanisms or as second-line treatment. Medical treatments are also necessary as chronic pain is the main long-lasting symptom. As evolutive syringomyelia is a severe disease with a high impact on quality of life, it is recommended to treat without delay. There is no evidence for surgery for incidental asymptomatic syringomyelia or hydromyelia. Finally, syringomyelia associated with intramedullary tumors resolves spontaneously after tumor resection. Syringomyelia is a rare disease, which requires a dedicated multidisciplinary approach, emphasizing the need for a nationwide scientific organization so as to offer optimal care to the patient.

Prospective Follow-up of Intramedullary Slitlike Cavities: A Consecutive Series of 48 Patients

Object: Predicting whether intramedullary slitlike cavity (SC) will worsen over time or remain stable is an outstanding clinical challenge. The aim of this study was to identify early features of SC (clinical and magnetic resonance imaging [MRI] findings).

Methods: We prospectively included all patients referred to our institution following the discovery of a SC and divided them in two groups: typical SC (defined as a cavity spanning fewer than three vertebrae, not enlarging the spinal cord, and located at the midline between the anterior third and posterior two-thirds of the spinal cord) or atypical SC (all others). Clinical evolution and changes in MRI features were evaluated during follow-up. In some patients, diffusion tensor imaging was performed and cervical cord cross-sectional area was analyzed.

Results: A total of 48 consecutive patients were included in the study. The mean follow-up was 58 months. Of the seven patients presenting with deficits at first consultation, two worsened and five remained stable. Of the 41 patients without deficits, seven worsened and 34 remained stable. None of the patients developed severe motor deficits or experienced enlargement of the cavity; 7% of patients who presented with typical SC worsened compared with 35% with atypical SC. The negative predictive value was 0.93 (P = 0.02).

Conclusion: Most patients remained stable and a subset of patients developed minor motor deficits. For clinical management, we propose surveillance of patients with a typical SC and close follow-up of those with an atypical SC and/or presenting with deficits.

Intramedullary spinal tumor-like lesions

The development of magnetic resonance imaging (MRI) has led to an increasingly frequent detection of changes in the spinal cord. The most common intramedullary lesions are: demyelinating; vascular; inflammatory; infectious; and congenital, largely called tumor-like lesions. Spinal cord tumors are relatively rare, as compared with brain tumors. The hardest task is to conclude whether the spinal cord lesion is a tumor or a tumor-like lesion. This review is intended to help evaluate the spinal cord and gives an overview of the tumor-like lesions occurring in the spinal cord along with their characteristic.

Clinical Application of Diagnostic Imaging of Chiari-Like Malformation and Syringomyelia

Chiari-like malformation (CM) and syringomyelia (SM) is a frequent diagnosis in predisposed brachycephalic toy breeds since increased availability of MRI. However, the relevance of that MRI diagnosis has been questioned as CM, defined as identification of a cerebellar herniation, is ubiquitous in some breeds and SM can be asymptomatic. This article reviews the current knowledge of neuroanatomical changes in symptomatic CM and SM and diagnostic imaging modalities used for the clinical diagnosis of CM-pain or myelopathy related to SM. Although often compared to Chiari type I malformation in humans, canine CM-pain and SM is more comparable to complex craniosynostosis syndromes (i.e., premature fusion of multiple skull sutures) characterized by a short skull (cranial) base, rostrotentorial crowding with rostral forebrain flattening, small, and ventrally orientated olfactory bulbs, displacement of the neural tissue to give increased height of the cranium and further reduction of the functional caudotentorial space with hindbrain herniation. MRI may further reveal changes suggesting raised intracranial pressure such as loss of sulci definition in conjunction with ventriculomegaly. In addition to these brachycephalic changes, dogs with SM are more likely to have craniocervical junction abnormalities including rostral displacement of the axis and atlas with increased odontoid angulation causing craniospinal junction deformation and medulla oblongata elevation. Symptomatic SM is diagnosed on the basis of signs of myelopathy and presence of a large syrinx that is consistent with the neuro-localization. The imaging protocol should establish the longitudinal and transverse extent of the spinal cord involvement by the syrinx. Phantom scratching and cervicotorticollis are associated with large mid-cervical syringes that extend to the superficial dorsal horn. If the cause of CSF channel disruption and syringomyelia is not revealed by anatomical MRI then other imaging modalities may be appropriate with radiography or CT for any associated vertebral abnormalities.

Prenatal and postnatal evaluation for syringomyelia in patients with spinal dysraphism

OBJECT

Syringomyelia can be diagnosed in isolation but is more commonly found in the presence of craniocervical junction anomalies or spinal dysraphism. The origin of syringomyelia has been hypothesized to be either congenital or acquired. The purpose of this study was to determine the incidence of syringomyelia within the fetal and postnatal population with neural tube defects (NTDs).

METHODS

A review was performed of the authors' fetal MRI database of pregnancies with imaging between March 2004 and November 2011 for evaluation of an intrauterine anomaly detected via prenatal ultrasonography. Those cases with an NTD were then selected and a chart review was performed of all prenatal and postnatal imaging as well as available clinical history.

RESULTS

A total of 2362 fetal MRI examinations were performed, and 109 of these were patients with an NTD. Of the 2362 studies reviewed, 2 cases of fetal syringomyelia were identified. Both fetal syrinxes were identified in fetuses with CSF flow disturbances (1 case each of encephalocele and myelomeningocele). Both fetal MRI examinations were performed late in gestation, at 31 and 38 weeks, respectively. The patient with an encephalocele was excluded from the spinal NTD population; therefore a syrinx was identified in 0.08% (2/2362) of the entire population of fetuses who underwent MRI, or 0.9% (1/109) of fetuses with a spinal NTD. Sixty-three of the 109 patients with an NTD had postnatal clinical data available for review. Twenty-nine (46%) of 63 had a syrinx identified during the follow-up period. Of this group, 50 patients had an open NTD and 27 (54%) of 50 developed a syrinx. Among the patients with an open NTD who developed a syrinx, only 7% did not have or develop hydrocephalus, compared with 35% of the patients who did not develop a syrinx (p < 0.05). There were nonsignificantly more frequent shunt revisions among those patients who developed a syrinx, and a syrinx developed in all patients who required surgical Chiari malformation decompression or tethered cord release. The initial identification of a spinal cord syrinx varied greatly between patients, ranging from 38 weeks gestation to greater than 4 years of age.

CONCLUSIONS

These data suggest that syringomyelia is not a congenital embryonic condition. A syrinx was not identified in fetuses who underwent imaging for other intrauterine anomalies. In the population of patients with NTDs who are known to be at high risk for developing syringomyelia, the pathology was only identified in 2 third-trimester fetuses or postnatally, typically in the presence of hydrocephalus, shunt placement, Chiari malformation decompression, or tethered cord release. The study supports the authors' hypothesis that a syrinx is an acquired lesion, most likely due to the effects of abnormal CSF flow.

Spontaneous regression of syringomyelia in a young patient with Chiari type I malformation

Syringomyelia is a disorder in which a cyst or cavity forms within the spinal cord. This cyst, called syrinx, can expand and elongate over time, destroying the spinal cord. We describe the case of a young patient with partial spontaneous regression of syringomyelia in Chiari I malformation, confirmed by magnetic resonance imaging three years after the diagnosis. During this period the patient did not experience any clinical symptoms. Although described in literature, spontaneous regression is an unusual event and very few cases have been reported. This case report supports the belief that conservative management together with both clinical and imaging periodic controls should be preferred in stable mild-symptomatic patients.

Experimental syringohydromyelia induced by adhesive arachnoiditis in the rabbit: changes in the blood-spinal cord barrier, neuroinflammatory foci, and syrinx formation

There are many histological examinations of syringohydromyelia in the literature. However, there has been very little experimental work on blood permeability in the spinal cord vessels and ultrastructural changes. We prepared an animal model of spinal adhesive arachnoiditis by injecting kaolin into the subarachnoid space at the eighth thoracic vertebra of rabbits. The animals were evaluated 4 months later. Of the 30 rabbits given kaolin injection into the cerebrospinal fluid, 23 showed complete circumferential obstruction. In the 7 animals with partial obstruction of the subarachnoid space, intramedullary changes were not observed. However, among the 23 animals showing complete obstruction of the subarachnoid space, dilatation of the central canal (hydromyelia) occurred in 21, and intramedullary syrinx (syringomyelia) was observed in 11. In animals with complete obstruction, fluorescence microscopy revealed intramedullary edema around the central canal, extending to the posterior columns. Electron microscopy of hydromyelia revealed a marked reduction of villi on the ependymal cells, separation of the ependymal cells, and cavitation of the subependymal layer. The dilated perivascular spaces indicate alterations of fluid exchange between the subarachnoid and extracellular spaces. Syringomyelia revealed that nerve fibers and nerve cells were exposed on the surface of the syrinx, and necrotic tissue was removed by macrophages to leave a syrinx. Both pathologies differ in their mechanism of development: hydromyelia is attributed to disturbed reflux of cerebrospinal fluid, while tissue necrosis due to disturbed intramedullary blood flow is considered to be involved in formation of the syrinx in 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.

Idiopathic syrinx in the pediatric population: a combined center experience

OBJECT

Discovery of a syrinx in a child, without a readily identifiable proximate cause such as a Chiari malformation, tumor, or site of tethering, is often a cause of concern for families and a source of consternation for clinicians. There is a paucity of data describing the natural history of an idiopathic syrinx in the pediatric population. The authors present the combined data of 2 major pediatric neurosurgical centers to describe their experience with this condition.

METHODS

Data were collected at Children's Hospital Boston and St. Louis Children's Hospital according to institutional review board-approved protocols and captured visits over a 2.5-year interval (October 2006-March 2009), with records reviewed if the patient had a preexisting diagnosis of syrinx. Patients were identified by ICD-9 codes derived from departmental databases. All pediatric patients (age < 19 years) in whom idiopathic syrinx had been diagnosed, as defined by MR imaging findings (dilated central canal in the spinal cord of ≥ 1 mm in axial dimension and extending over at least 2 vertebral levels), were included.

RESULTS

Forty-eight patients met the criteria for idiopathic syrinx during this period, and in 32 of them detailed follow-up imaging was available. Discovery of a syrinx was incidental in 6 patients, whereas the others were referred for imaging because of the presence of pain, neurological symptoms, scoliosis, or skin markings. The average age at the first MR imaging session was 9.7 years, with a mean syrinx size of 4 mm (range 1.2-9.4 mm). The majority (52%) of patients had a thoracic syrinx, with the average lesion spanning 7.1 vertebral levels. The average follow-up was 23.8 months (range 2-64 months), and subgroups of patients with < 3 years and ≥ 3 years of follow-up were independently reviewed. Overall, symptoms improved in 34% and worsened in 9%; 57% of the patients remained asymptomatic or stable. Radiographically (in the subgroup of 32 patients with detailed follow-up imaging), syrinx size decreased in 25% of patients, increased in 12.5%, and remained unchanged in 62.5%, with no apparent correlation between change in syrinx size and clinical symptoms.

CONCLUSIONS

Clinically, children with an idiopathic syrinx remained asymptomatic, stable, or improved in 91% of cases. The majority of syringes (87.5%) remained stable or shrank over time, with no apparent correlation between changes in size and changes in symptoms. Although longer follow-up is needed, these data suggest that the natural history of an idiopathic syrinx in children is benign, and that repeated imaging may not be necessary.

Defining the line between hydromyelia and syringomyelia. A differentiation is possible based on electrophysiological and magnetic resonance imaging studies

PURPOSE

With the frequent use of magnetic resonance imaging (MRI), patients with subtle and diffuse symptoms due to small syrinx cavities increasingly present to neurosurgical care. In this respect, a dilated central canal, hydromyelia, must be separated from patients with true syringomyelia with an underlying disorder, as they do not share clinical and radiological features. We hypothesize that a differentiation of these two entities with distinct diagnostic tools is possible.

METHODS

To describe the entity of hydromyelia, we excluded all patients from the syringomyelia database (n = 142) with any obvious cause of a syringomyelia, any objective neurological deficits on clinical examination, pathological results on electrophysiological monitoring (SSEP, MEP, silent periods) or a widening of the spinal cord cavity of more than 6 mm on MRI [routine acquisitions with FLAIR, T1/T2-weighted images, Cine and CISS (constructive interference in steady-state) studies]. Life quality was assessed through SF-36 questionnaires and an individualized questionnaire for the clinical history, pain and alternative therapies.

RESULTS

Forty patients (15 males/25 females) matched the criteria of a hydromyelia. With a mean age of 36.7 years (range 11-62), they almost all presented with pain (79%) or dysaesthesia of the limbs, with some having been an incidental finding (10%). Over a follow-up time of 36.9 months (range 6-93) there was no neurological or radiological deterioration.

CONCLUSIONS

Patients with a hydromyelia do not share clinical or radiological characteristics with patients harbouring a true syringomyelia. As hydromyelia does not represent a disease with an underlying pathology, no clinical or radiological progression has been seen. With sophisticated diagnostic tools to rule out any pathology this subset of patients can be identified.

Three-dimensional constructive interference in steady-state magnetic resonance imaging in syringomyelia: advantages over conventional imaging

OBJECT

Neuroradiology has become indispensable in detecting the pathophysiology in syringomyelia. Constructive interference in steady-state (CISS) magnetic resonance (MR) imaging can provide superior contrast at the sub-arachnoid tissue borders. As this region is critical in preoperative evaluation, the authors hypothesized that CISS imaging would provide superior assessment of syrinx pathology and surgical planning.

METHODS

Based on records collected from a database of 130 patients with syringomyelia treated at the authors' institution, 59 patients were prospectively evaluated with complete neuroradiological examinations. In addition to routine acquisitions with FLAIR, T1- and T2-weighted, and contrast-enhanced MR imaging series, the authors obtained sagittal cardiac-gated sequences to visualize cerebrospinal fluid (CSF) pulsations and axial 3D CISS MR sequences to detect focal arachnoid webs. Statistical qualitative and quantitative evaluations of spinal cord/CSF contrast, spinal cord/CSF delineation, motion artifacts, and artifacts induced by pulsatile CSF flow were performed.

RESULTS

The 3D CISS MR sequences demonstrated a contrast-to-noise ratio significantly better than any other routine imaging sequence (p < 0.001). Moreover, 3D CISS imaging can detect more subarachnoid webs and cavitations in the syrinx than T2-weighted MR imaging with less flow-void artifact. The limitation of 3D CISS imaging is a susceptibility to motion artifacts that can cause reduced spatial resolution. Lengthy acquisition times for axial segments can be reduced with multiplanar reconstruction of 3D CISS-generated sagittal images.

CONCLUSIONS

Constructive interference in steady-state imaging is the MR sequence of choice in the preoperative evaluation of syringomyelia, allowing significantly higher detection rates of focal subarachnoid webs, whereas standard T2-weighted MR imaging shows turbulent CSF flow voids. Constructive interference in steady-state MR imaging enables the neurosurgeon to accurately identify cases requiring decompression for obstructed CSF. Motion artifacts can be eliminated with technical variations.

Midline septa in the lumbo-sacral thecal sac: Acquired abnormality or developmental anomaly? The equivalent of diastematomyelia occurring below the spinal cord?

Careful analysis of over 400 patients radiologically diagnosed with arachnoiditis showed a subgroup of eight patients with a specific set of imaging signs that suggest a pre-existing developmental abnormality mimicking the appearance of arachnoiditis. These cases have been collected over a 15-year period. No autopsy or surgical proof is available. All patients have (i) the presence of a well-defined midline septum in the sagittal plane that splits the thecal sac, usually symmetrically, in the lower lumbar or sacral region, below the level of the spinal cord; (ii) the absence of adjacent epidural fibrosis that one would expect if the septation had been caused by surgical intervention or trauma; (iii) the preservation of cerebrospinal fluid within the nerve root sheaths and around the nerve roots at the level of the septation; and in four cases (iv) the presence of either calcification or bone in this midline septum, yet nowhere else in the theca or epidural space. These cases suggest a developmental variant called, for want of a better term, 'split lumbo-sacral thecal sac' analogous to diastematomyelia but not involving the spinal cord. This variant is potentially confused with arachnoiditis or thecal scarring in the lumbo-sacral sac.

A craniocervical injury-induced syringomyelia caused by central canal dilation secondary to acquired tonsillar herniation. Case report

The authors report on a 19-year-old man with an acquired tonsillar herniation caused by a craniocervical junction injury in which serial magnetic resonance (MR) images demonstrated patent and isolated segments of the central canal participating in the dilation and then formation of a cervical syrinx. The patient was involved in a motor vehicle accident; he developed tonsillar herniation as a complication of subarachnoid and epidural hemorrhage, predominantly observed around the cisterna magna and upper cervical canal. Repeated MR images obtained over an 11-month period indicated the for mation and acute enlargement of the syrinx. Ten months after the accident, the patient presented with sensory disturbance in both upper extremities and spasticity due to syringomyelia. He underwent craniocervical decompressive surgery and doraplasty, which reduced the size of syringomyelia. The authors postulate that the patent central canal may play a role in determining the location of a syrinx remote from a focus of cerebrospinal fluid obstruction.