Incidentally identified syringomyelia associated with Chiari I malformations: is early interventional surgery necessary?

Natural history of Chiari I malformation with syrinx and dilatation of the central canal in the pediatric population: the CHEO experience

PURPOSE

Given that syrinx is often considered an indication of surgery in children with Chiari I malformation (CM1), understanding of the natural history of these patients is very challenging. In this study, we investigate the natural history of children with CM1 that have syrinx and/or prominence of the central canal on presentation.

METHODS

All pediatric Chiari I patients who had syrinx and/or prominence of the central canal who underwent MR imaging of the head and spine from 2007 to 2020 were reviewed. Patients were divided into 3 groups (early surgery, delayed surgery, and conservative management). We focused on those patients who did not initially undergo surgery and had at least 1 year of clinical follow-up. We assessed if there were any radiological features that would correlate with need for delayed surgical intervention.

RESULTS

Thirty-seven patients met the inclusion criteria. Twenty-one patients were female and 16 were male. The mean age at presentation was 8.7 (5.8 SD). Fourteen (38%) patients had early surgical intervention, with a mean of 2.5 months after initial presentation, 8 (16%) had delayed surgery due to new or progressive neurological symptoms and 46% of patients did not require intervention during follow-up. The length of tonsillar herniation and the position of the obex were associated with the need of surgery in patients who were initially treated conservatively.

CONCLUSION

In pediatric patients with CM1 with syringomyelia and prominence of the central canal, conservative treatment is initially appropriate when symptoms are absent or mild. Close follow-up of patients with CM1 and dilatation of the central canal who have an obex position below the foramen magnum and greater tonsillar herniation is suggested, as these patients show a trend towards clinical deterioration over time and may require earlier surgical intervention.

Brace treatment for scoliosis secondary to chiari malformation type 1 or syringomyelia without neurosurgical intervention: A matched comparison with idiopathic scoliosis

PURPOSE

To evaluate the effectiveness of brace treatment in patients with Chiari malformation type 1 (CM-1) or syringomyelia associated scoliosis without neurosurgical intervention.

METHODS

This was a retrospective case-control study. 34 CM-1 or syringomyelia (CMS) patients who received brace treatment without neurosurgical intervention were recruited. Another 68 matched patients with idiopathic scoliosis who received bracing served as the control group. The matching criteria included gender, age (± 1 years), Risser sign (± 1 grade), initial curve magnitude (± 5°), curve patterns and follow-up time (± 6 months). Patients who encountered curve progression and scoliosis surgery were compared between different groups.

RESULTS

Until the last visit, 16 (47%) patients in CMS group and 18 (26%) patients in IS group occurred curve progression; 9 (26%) patients and 15 (22%) patients underwent scoliosis surgery, respectively. Compared to idiopathic scoliosis, patients with CMS-associated scoliosis had a significantly higher rate of curve progression (P = 0.038). However, no significant difference was observed between two groups regarding to the rate of surgery (P = 0.867). Patients with combined CM-1 and syringomyelia had a higher rate of surgery than patients with isolated CM-1 or syringomyelia (P = 0.049). The double major curve pattern was identified as the risk factor for curve progression.

CONCLUSION

Brace treatment is effective for CMS-associated scoliosis without neurosurgical intervention. Compared to idiopathic scoliosis, brace can provide similar prevention for scoliosis surgery in CMS patients, but slight or moderate curve progression may occur. Specifically, patients with combined CM-1 and syringomyelia should be followed closely with a higher expectation of curve progression.

Preoperative measurements on MRI in Chiari 1 patients fail to predict outcome after decompressive surgery

Background

The purpose of our study was to research the parameters of magnetic resonance imaging (MRI) that would predict the outcome of surgery in patients with Chiari 1 malformation (CM1) and to evaluate changes in MRI parameters after surgery.

Methods

Fifty-one patients (19 children, 13 adolescents, and 19 adults) operated on due to CM1 in Oulu University Hospital between 2004 and 2018 were evaluated. Seventeen parameters were measured from the preoperative MRI and 11 from the postoperative MRI. The correlations between the MRI parameters and the clinical variables before and after surgery were analyzed.

Results

The majority (88.2%) of the patients had favorable surgical outcomes. Postoperatively, subjective symptoms improved in 88.6% of the patients and syringomyelia in 81.8%. The location of the cerebellar tonsils, when measured in relation to the C2 synchondrosis or the end plate, postoperatively moved cranially in 51.0% (n = 26), did not change in 27.4% (n = 14), and moved caudally in 21.6% (n = 11) of the patients. However, neither the location of the tonsils nor any other parameters measured from pre- or postoperative MRI correlated with the patients’ symptoms or surgical outcomes.

Conclusions

No specific parameters on preoperative MRI evaluation were predictive of the outcome of surgery, emphasizing clinical examination in surgical decision-making. Furthermore, the postoperative MRI parameters did not correlate with the surgical outcomes. Thus, routine postoperative imaging is suggested only for patients with preoperatively diagnosed syringomyelia or worsening of symptoms.

Natural History and Conservative Treatment Options in Chiari Malformation Type I in Adults: A Literature Update

Over the years, knowledge regarding the natural history of Chiari malformation type I (CM-I) has improved. However, there are still uncertainties in the literature regarding asymptomatic and oligosymptomatic patients with CM-I. We performed a literature review in order to determine the natural history of CM-I in symptomatic patients who were not operated and in asymptomatic adult patients. Among symptomatic patients, the most frequent symptom was headache (77%). Cough-related headache alone (34%), migraine-related headache alone (21.4%), and both cough- and migraine-related headaches (21.8%) were the most prevalent forms of headache. Some symptoms improved more effectively with surgical treatment options; cough-related headaches improved by 95% following surgery and by 40% following conservative treatment. Other headache types improved by 93% and 61.5% following conservative and surgical treatments, respectively. Patients diagnosed with asymptomatic or oligosymptomatic CM-I may improve over time or stabilize with conservative treatment. There is great heterogeneity in the literature regarding the diagnostic criteria for CM-I. Owing to the heterogeneity among the articles identified for this review, there is no consensus regarding the precise indications for surgery in asymptomatic patients. The natural CM-I history in asymptomatic patients reveals a favorable evolution.

International survey on the management of Chiari 1 malformation and syringomyelia: evolving worldwide opinions

INTRODUCTION

In 2003, pediatric neurosurgeons were surveyed under the auspices of the education committee of the International Society for Pediatric Neurosurgery (ISPN) to determine prevailing opinions regarding the management of Chiari I malformation (C1M) with and without associated syringomyelia. In the ensuing years, there has been further information from multiple C1M studies, with regards to indications, success rates of different surgical interventions, and complications. The purpose of this study was to re-evaluate current opinions and practices in pediatric C1M.

MATERIALS AND METHODS

Pediatric neurosurgeons worldwide were surveyed, using an e-mail list provided by the ISPN communication committee chairperson. Respondents were given scenarios similar to the 2003 C1M survey in order to determine opinions regarding whether to surgically intervene, and if so, with which operations.

RESULTS

Of 300 surveys electronically distributed, 122 responses were received (40.6% response rate)-an improvement over the 30.8% response rate in 2003. Pediatric neurosurgeons from 34 different countries responded. There was broad consensus that non-operative management is appropriate in asymptomatic C1M (> 90%) as well as asymptomatic C1M with a small syrinx (> 65%). With a large syrinx, a majority (almost 80%) recommended surgical intervention. Scoliotic patients with CIM were generally offered surgery only when there was a large syrinx. There has been a shift in the surgical management over the past decade, with a bone-only decompression now being offered more commonly. There remains, however, great variability in the operation offered.

CONCLUSION

This survey, with a relatively strong response rate, and with broad geographic representation, summarizes current worldwide expert opinion regarding management of pediatric C1M. Asymptomatic C1M and C1M with a small syrinx are generally managed non-operatively. When an operation is indicated, there has been a shift towards less invasive surgical approaches.

Spontaneous Resolution of Chiari 1-Associated Syringomyelia: A Report of Two Cases

BACKGROUND

Traditional teaching is that Chiari 1 malformations with syrinx should be operated as soon as possible. We present 2 cases of a radiologically proven Chiari 1 malformation with syrinx which were treated nonoperatively and improved radiologically.

METHODS

Two children with an MRI-proven Chiari 1 malformations were followed up nonoperatively for 7 years (2010-2017). One was a boy aged 8 years and the other a girl aged 9 years at first presentation. Their parents were not interested in a surgical option and so it was decided to adopt a wait-and-watch policy. Both patients were followed up with a regular half-yearly clinical examination and yearly MRI studies (2010-2017).

RESULTS

It was found that, in both of them, the initial cough during swallowing and the headache improved. Serial MRI showed that the hind-brain protrusion was reduced and syrinx diminished or resolved well.

CONCLUSIONS

Some children with Chiari I and syringomyelia may show spontaneous resolution of symptoms and syringomyelia. Large registry studies will be needed to determine how likely it is that Chiari-associated syringes will resolve, and whether there are particular anatomic or neurologic differences between those who require surgery and those who don't.

Chiari type I malformation of infants and toddlers

OBJECTIVES

Chiari I malformation has been a well-recognized clinical entity; however, its occurrence among infants and toddlers is unusual. Their clinical presentations may be different from other age groups due to their lack of effective verbal communication. The authors analyze their personal series of patients focusing on symptomatology and MRI characteristics. Treatment methods, results, and outcome are analyzed in order to identify appropriate surgical management among infants and toddlers with Chiari I malformation.

METHODS

The authors retrospectively reviewed 16 patients who were diagnosed and surgically treated between 2007 and 2014 during the first 3 years of life with minimum follow-up of 3 years. We focused on the presenting symptoms, magnetic resonance imaging findings, and surgical techniques used for posterior fossa decompression (PFD) and their postoperative outcome.

RESULTS

Twelve patients (75%) presented with signs of headaches such as irritability, inconsolable crying, head grabbing, and/or arching back. Ten patients (62.5%) presented with oropharyngeal and/or respiratory symptoms such as emesis, choking, gagging, snoring, sleep apnea, breathing pause, and/or vocal cord palsy. Only one patient had segmental cervical hydromyelia. At the first surgery, ten patients had PFD with dural scoring (Type 1 procedure), while six others had PFD with duraplasty (Type 2 procedure) with thermal reduction of the cerebellar tonsils in four. Following the first operation, all initially had varying degrees of symptomatic improvement; however, seven patients subsequently had symptomatic recurrence. Persistent crowding at the PFD site on the postoperative imaging indicated greater risk of recurrences in both Type 1 procedure and Type 2 procedure groups. Of seven patients who needed a second operation, fivewere after Type 1 procedure and the two were after Type 2 procedure. The difference of recurrence rates between these two groups is not significant. CSF-related complications occurred in 4 out of 11 patients who had Type 2 procedure (one after primary decompression and three after the second decompression for recurrence).

CONCLUSION

Young patients lacking effective verbal communication often present their Chiari I malformation differently from olderage groups. Behavioral changes indicative of headaches/irritability and oropharyngeal/respiratory symptoms are the primary presenting symptoms. The recurrence rate tends to be higher among the patients after Type 1 procedure (particularly those younger than 18 months) than after Type 2 procedure. We observed that duraplasty at primary or at redo PFD provides for better decompression and long-term outcome. However, one should keep it in mind that there is risk of CSF-related complications following duraplasty, particularly higher tendency after redo PFD.

Chiari type I malformation with cervicothoracic syringomyelia subterfuge as flail arm syndrome

Chiari type I malformation with cervicothoracic syringomyelia although very common in clinical practice usually in children can progress slowly and mimic muscular dystrophies in adulthood. We present a rare adult case of Chiari type I malformation with cervicothoracic syringomyelia subterfuge as Flail arm syndrome. A 44-year-old man was diagnosed with congenital type I Chiari malformation with cervicothoracic syringomyelia about 21 years ago without surgery. His health status deteriorated over the years until 21 days prior to presentation when he had severe pain in the right knee. In his upper limbs, he had bilateral corresponding severe weakness of 0/5 proximal strength and 0/5 strength in his distal muscles. Magnetic resonance imaging (MRI) revealed an enlargement of the spinal cord from C1-C4 level with a mass that appeared hypo-dense on T1 and hyperdense on T2. Syringomyelia is a potentially serious neurologic condition that can mimic other neuromuscular disorders. Early detection and diagnosis with MRI is crucial to avoid irreversible neurological complications. We suggest that whether asymptomatic or symptomatic, decompressive surgery should be carried out to allow for free flow of cerebrospinal fluid thereby improving the quality of life for the patient.

[Clinical magnetic resonance imaging : Frequent incidental cerebral findings]

The increasing use of magnetic resonance imaging (MRI) in clinical diagnostics means that patients and physicians are confronted more often with incidental findings. In the literature there are fluctuating data on the incidence of such findings and guidelines concerning the further procedure exist in only very few cases, such as incidental aneurysms and pituitary adenomas. The diagnostic and therapeutic implications which can be derived from incidental findings depend on multiple factors, such as anatomical location, patient age, comorbidity and patient wishes. For this reason it often makes sense to refer patients with incidental findings to an interdisciplinary neurological center at an early stage. In this review frequent incidental cerebral findings, epidemiological data, imaging criteria and, where possible, recommendations for the further procedure are shown.

"Stealth cranioplasty:" A novel endeavor for symptomatic adult Chiari I patients with syringomyelia: Technical note, appraisal, and philosophical considerations

Aim and Objective:

In this article, we describe a novel technique of reconstruction of posterior fossa by cranioplasty with use of preshaped titanium mesh following posterior fossa decompression (PFD) for Chiari malformation type I (CMI) with syringomyelia (SM) in symptomatic adults.

Materials and Methods:

Eleven patients underwent limited PFD and expansive cranioplasty with preshaped titanium mesh, what we term as “Stealth Cranioplasty” (SCP), following arachnoid preserving duraplasty (APD) and hexagonal tenting of the duraplasty with the cranioplasty (HTDC) for the management of symptomatic adult CMI with SM. All these patients had syringes extending from 3 to >10 vertebral levels.

Results:

Seven male and four female symptomatic CMI adult patients, between age ranges of 22 and 44 years (mean 29.45 years), presented with different neurological symptoms related to CMI and SM for 6–84 months (mean 37.09 months). All the patients underwent PFD, APD followed by SCP and HTDC and were followed up for 7–54 months (mean 35.90 months). Of 11 patients, 8 patients improved according to the Chicago Chiari Outcome Scale (CCOS) with score of 13–15 while 3 patients remained unchanged with CCOS of 12, and there was no worsening. There was no complication related to Chiari surgery in any of the patients. All the patients had good reestablishment of cisterna magna. Two patients had marked reduction of syrinx while eight patients had moderate-to-mild reduction and one patient had no change of syrinx. None of the patients needed redo surgery.

Conclusion:

SCP is an effective, fruitful, and cost-effective technique for the management of symptomatic adult CMI with SM. This technique has the advantages of preventing complications and recurrences in addition to the improvement of symptoms by addressing the basic pathology.

Natural and surgical history of Chiari malformation Type I in the pediatric population

OBJECT The natural and surgical history of Chiari malformation Type I (CM-I) in pediatric patients is currently not well described. In this study the authors discuss the clinical and radiological presentation and outcomes in a large cohort of pediatric CM-I patients treated with either conservative or surgical management. METHODS The authors retrospectively reviewed 95 cases involving pediatric patients with CM-I who presented between 2004 and 2013. The patients ranged in age from 9 months to 18 years (mean 8 years) at presentation. The cohort was evenly split between the sexes. Twenty-five patients underwent posterior fossa decompression (PFD) with either dural splitting or duraplasty. Seventy patients were managed without surgery. Patients were followed radiologically (mean 44.8 months, range 1.2-196.6 months) and clinically (mean 66.3 months, range 1.2-106.5 months). RESULTS Seventy patients were treated conservatively and followed with serial outpatient neurological and radiological examinations, whereas 25 patients were treated with PFD. Of these 25 surgical patients, 11 were treated with duraplasty (complete dural opening) and 14 were treated with a dura-splitting technique (incomplete dural opening). Surgical intervention was associated with better clinical resolution of symptoms and radiological resolution of tonsillar ectopia and syringomyelia (p = 0.0392). Over the course of follow-up, 20 (41.7%) of 48 nonsurgical patients who were symptomatic at presentation experienced improvement in symptoms and 18 (75%) of 24 symptomatic surgical patients showed clinical improvement (p = 0.0117). There was no statistically significant difference in resolution of symptoms between duraplasty and dura-splitting techniques (p = 0.3572) or between patients who underwent tonsillectomy and tonsillopexy (p = 0.1667). Neither of the 2 patients in the conservative group with syrinx at presentation showed radiological evidence of resolution of the syrinx, whereas 14 (87.5%) of 16 patients treated with surgery showed improvement or complete resolution of syringomyelia (p = 0.0392). In the nonsurgical cohort, 3 patients (4.3%) developed new or increased syrinx. CONCLUSIONS The overwhelming majority of CM-I patients (92.9%) managed conservatively do not experience clinical or radiological progression, and a sizeable minority (41.7%) of those who present with symptoms improve. However, appropriately selected symptomatic patients (sleep apnea and dysphagia) and those presenting with syringomyelia should be considered surgical candidates because of the high rates of clinical (75%) and radiological improvement (87.5%).

Chiropractic care for headaches and dizziness of a 34-year-old woman previously diagnosed with Arnold-Chiari malformation type 1

OBJECTIVE

The purpose of this case study is to describe the chiropractic care of a patient with headaches and dizziness.

CLINICAL FEATURES

A 34-year-old woman with a history of headaches, dizziness, photophobia, and temporary loss of vision aggravated by postural positions while bending forward sought conservative care for her symptoms. She reported a prior diagnosis of Arnold-Chiari malformation (ACM) type 1 by magnetic resonance imaging in 2005 that revealed descending cerebellar tonsils measured at 5 mm with an impression of ACM type 1. A new magnetic resonance image taken in 2013 indicated the cerebellar tonsils measured at 3 mm and did not project through the plane of the foramen magnum. The diagnosis of ACM type 1 was no longer applicable; however, the signs and symptoms of ACM type 1 persisted.

INTERVENTION AND OUTCOME

She was treated using cervical chiropractic manipulation using diversified technique. The dizziness and headache were resolved after 3 visits. At her 3-month follow-up, she continued to be symptom-free.

CONCLUSION

A patient with headaches and dizziness and a previous diagnosis of ACM type 1 responded positively to chiropractic care.

Association of increased body mass index with Chiari malformation Type I and syrinx formation in adults

Object

In this paper the authors describe an association between increased body mass index (BMI) and Chiari malformation Type I (CM-I) in adults, as well as its relationship to the development of syringomyelia.

Methods

In the period between January 2004 and December 2011, the senior author reviewed the data for all CM-I patients with or without syringomyelia and neurological deficit. Analyzed factors included clinical status (headaches and neurological signs), radiological characteristics of syringomyelia (diameter and vertical extent of syrinx), BMI, and relationship of age to BMI, syrinx diameter, and vertical extent of syrinx.

Results

Sixty consecutive adults had CM-I, 26 of whom also had syringomyelia. The mean BMI among all patients was 30.35 ± 7.65, which is Class I obesity (WHO), and was similar among patients with or without syringomyelia. Extension of the vertical syrinx was greater in overweight patients (p = 0.027) than in those with a normal body weight. Evidence of de novo syrinx formation was found in 2 patients who gained an average BMI of 10.8 points. After repeated decompression and no change in holocord syrinx width or vertical extent, a reduction in the syrinx was seen after BMI decreased 11.7 points in one individual. No correlation was found between patient age and BMI, age and vertical extension of the syrinx, and age and diameter of the syrinx.

Conclusions

An association between increased BMI and CM-I in adults was recognized. Gaining weight may influence the de novo creation of a syrinx in adults who previously had minimally symptomatic or asymptomatic CM-I, and reducing weight can improve a syrinx after unsuccessful surgical decompression. Therefore, a reduction in body weight should be recommended for all overweight and obese patients with CM-I.

Rapidly progressing monoparesis caused by Chiari malformation type I without syringomyelia

BACKGROUND

Patients with Chiari malformation type I (CM-I) can manifest neurological symptoms, such as headache, neck pain, dysesthesia, swallowing disturbance, and paresis, which are usually stable or slowly progressive even if syringomyelia is coexistent. In some instances, however, acute onset of neurological symptoms has been reported but the pathogenetic mechanism and subsequent clinical course have not been explained. In those cases, it was reported that urgent treatment of foramen magnum decompression (FMD) was very effective. This work reports that an 11-year-old girl with CM-I subacutely developed unique symptoms and that urgent treatment of FMD was very effective.

CASE DESCRIPTION

We present here an 11-year-old girl with CM-I who subacutely developed dysphagia, left upper extremity monoparesis and sensory dysesthesia, with the limb assuming a peculiar posture at rest, with the wrist in extension and the elbow joint in flexion. Although her symptoms were assumed to be due to previously diagnosed CM-I without syringomyelia, no differences on magnetic resonance imaging (MRI) could be found except for slight change in the shape of tonsils compared with the previous ones. FMD and C1 removal with duraplasty was performed and resulted in an excellent neurological recovery.

CONCLUSION

This case is a reminder that the presence of a new neurological deficit referable to nuclei within, or tracts that traverse, the cerebromedullary junction is a firm surgical indication for FMD in a patient with CM-I. MRI was nearly identical during the asymptomatic and symptomatic periods in this case, and did not explain the timing of symptom onset.

Natural history of untreated syringomyelia in pediatric patients

OBJECT

The natural history of syringomyelia in pediatric patients remains uncertain. Although symptomatic and operative cases of syringomyelia are well studied, there are fewer articles in the literature on the nonoperative syrinx and its clinical and radiological course. The purpose of this research was to analyze the natural history of untreated syringomyelia in pediatric patients presenting with minimal neurological symptoms.

METHODS

A review of the neurosurgery database at British Columbia's Children's Hospital identified all pediatric patients (< 18 years of age) with syringes identified on MR imaging. Patients were included in this study if they had at least 2 MR images of the spine, at least 1 year apart, while receiving nonoperative treatment. Magnetic resonance imaging was used to determine changes in the size of the syrinx over time. Clinic notes were analyzed to establish demographic and clinical features and to determine any clinical changes over time.

RESULTS

A total of 17 patients were included in the study. Symptoms at presentation were often mild and included limb numbness (3 cases), headaches (2 cases), mild sensory deficits (2 cases), mild motor deficits (3 cases), and intermittent incontinence (7 cases). The consultant neurosurgeon believed that the syrinx was not contributing to the symptoms in these 17 patients. The syrinx either remained unchanged (7 cases) or diminished in size (8 cases) in a total of 15 patients (88%). In the remaining 2 patients the authors noted an increase in syrinx size, in 1 of whom the clinical course also worsened. Both of these patients had a Chiari malformation and subsequently underwent craniocervical decompression. Overall, the mean change was -0.7 mm of maximal axial diameter (range -2.6 to +2.7 mm). Sixteen patients (94%) exhibited no worsening of symptoms over time.

CONCLUSIONS

Syringomyelia often remains stable in patients receiving nonoperative treatment. However, given that 2 (12%) of 17 syringes in this series enlarged, it is likely appropriate to include periodic imaging in the follow-up of these cases.

Spontaneous resolution of a Chiari malformation Type I and syrinx after supratentorial craniotomy for excision of a cavernous malformation

The pathogenesis of Chiari malformation Type I (CM-I) and associated syringomyelia is incompletely understood. Patients often present in middle age with incidental or minimally symptomatic CM-I, whose management is controversial. One option is clinical and radiographic observation of asymptomatic and minimally symptomatic patients. The authors here present the case of a 36-year-old woman who had been monitored for 6 years for a minimally symptomatic CM-I and cervicothoracic syrinx. After 5 years of follow-up, she suffered spontaneous rupture of a cerebral cavernous malformation when she was 27 weeks pregnant. The ruptured cavernous malformation and hematoma were operatively managed via a right frontal craniotomy. Ten months after the craniotomy for resection of the ruptured cavernous malformation, follow-up MRI demonstrated resolution of the CM-I and syrinx. Few similar cases have been reported in adults. This case argues for the presence of dynamic factors in the development and maintenance of CM-I and supports the nonoperative treatment of asymptomatic and minimally symptomatic patients.

Spontaneous resolution of syringomyelia in an adult patient with tight cisterna magna

Spontaneous resolution of syringomyelia in adult patients with Chiari malformation is exceptionally rare, with only 10 cases having been reported. A 21-year-old man working as a carpenter presented with a 1-year history of paresthesias in his right arm. A magnetic resonance imaging scan disclosed a cervicothoracic syrinx associated with tight tonsillar impaction of the cisterna magna without herniation. The patient left the carpentry job and underwent close monitoring with serial clinical and neuroradiological controls. The patient's symptoms gradually disappeared and magnetic resonance imaging studies revealed progressive shrinkage of the syrinx despite persistence of crowding of posterior fossa structures at the level of the foramen magnum. This case suggests that spontaneous resolution of syringomyelia can occasionally be triggered by the cessation of daily physical strain in patients with tight cisterna magna. Health care professionals should be aware that strenuous physical activities could affect the natural history of syringomyelia.

Sudden onset of Chiari malformation Type I in previously asymptomatic patients

Chiari malformation Type I (CM-I) is usually suspected in patients with slowly progressing neurological symptoms. However, in some instances, especially if syringomyelia is associated, an abrupt clinical onset is reported and is accompanied by an acknowledged risk of potentially severe clinical signs or even sudden death. Little is known about such a critical course in CM-I/syringomyelia complex. The authors describe 3 challenging cases of the abrupt onset of CM-I/syringomyelia to reveal more information on the clinical presentation and pathogenetic mechanisms of this sudden and potentially severe clinical phenomenon: a 38-year-old man experienced acute respiratory failure requiring intubation following acute decompensation of hydrocephalus associated with Noonan syndrome, a 1-year-old boy had sudden hemiparesis and Horner syndrome after a minor head/neck injury, and a 2.5-year-old boy presented with quickly progressing tetraplegia and dyspnea after a mild flexion and extension neck injury a few hours before. All 3 patients showed a CM-I/syringomyelia complex at diagnosis, and all of them had a good neurological outcome after surgery despite the ominous clinical presentation.

Chiari malformation Type I and syrinx in children undergoing magnetic resonance imaging

OBJECT

Chiari malformation Type I (CM-I) with an associated spinal syrinx is a common pediatric diagnosis. A better understanding of the relative age-related prevalence and MR imaging characteristics of these associated conditions may lead to improved treatment decisions.

METHODS

The authors performed a retrospective review of 14,116 consecutive individuals 18 years of age or younger who had undergone brain or cervical spine MR imaging at the University of Michigan between November 1997 and August 2008. In the patients with CM-I, demographic, clinical, and radiographic information was recorded.

RESULTS

Five hundred nine children (3.6%) with CM-I were identified. Among these patients, 23% also had a spinal cord syrinx, and 86% of the syringes were found in the cervical spine. The MR imaging prevalence of CM-I with a syrinx was 1.2% in girls and 0.5% in boys (p < 0.0001). The severity of impaired CSF flow at the foramen magnum was associated with the amount of tonsillar herniation (p < 0.0001) and conformation of the tonsils (p < 0.0001). Patients with CM-I were treated surgically in 35% of cases; these patients exhibited more severe tonsillar herniation (p < 0.0001) and impaired CSF flow (p < 0.0001) as compared with those who did not undergo surgery. On imaging, 32% of all the patients with CM-I were considered symptomatic by the treating physician. Patients were more likely to be considered symptomatic if they were female, had a syrinx, displayed abnormal tonsillar pulsations, or had a greater amount of tonsillar herniation.

CONCLUSIONS

In this study the authors describe the age-related prevalence and MR imaging characteristics of CM-I and its association with a syrinx and other abnormalities in a large group of children who underwent MR imaging for any indication. Syringes are more common in older children, in girls, and in patients with a greater degree of tonsillar descent and CSF flow impairment.

Natural history of Chiari malformation Type I following decision for conservative treatment

OBJECT

The natural history of the Chiari malformation Type I (CM-I) is incompletely understood. The authors report on the outcome of a large group of patients with CM-I that were initially selected for nonsurgical management.

METHODS

The authors identified 147 patients in whom CM-I was diagnosed on MR imaging, who were not offered surgery at the time of diagnosis, and in whom at least 1 year of clinical and MR imaging follow-up was available after the initial CM-I diagnosis. These patients were included in an outcome analysis.

RESULTS

Patients were followed clinically and by MR imaging for a mean duration of 4.6 and 3.8 years, respectively. Of the 147 patients, 9 had new symptoms attributed to the CM-I during the follow-up interval. During this time, development of a spinal cord syrinx occurred in 8 patients; 5 of these patients had a prior diagnosis of a presyrinx state or a dilated central canal. Spontaneous resolution of a syrinx occurred in 3 patients. Multiple CSF flow studies were obtained in 74 patients. Of these patients, 23 had improvement in CSF flow, 39 had no change, and 12 showed worsening CSF flow at the foramen magnum. There was no significant change in the mean amount of cerebellar tonsillar herniation over the follow-up period. Fourteen patients underwent surgical treatment for CM-I. There were no differences in initial cerebellar tonsillar herniation or CSF flow at the foramen magnum in those who ultimately underwent surgery compared with those who did not.

CONCLUSIONS

In patients with CM-Is that are selected for nonsurgical management, the natural history is usually benign, although spontaneous improvement and worsening are occasionally seen.

Outcomes in pediatric patients with Chiari malformation Type I followed up without surgery

OBJECT

The natural history of untreated Chiari malformation Type I (CM-I) is poorly defined. The object of this study was to investigate outcomes in pediatric patients with CM-I who were followed up without surgical intervention.

METHODS

The authors retrospectively reviewed 124 cases involving patients with CM-I who presented between July 1999 and July 2008 and were followed up without surgery. The patients ranged in age from 0.9 to 19.8 years (mean 7 years). The duration of follow-up ranged from 1.0 to 8.6 years (mean 2.83 years). Imaging findings, symptoms, and findings on neurological examinations were noted at presentation and for the duration of follow-up.

RESULTS

The mean extent of tonsillar herniation at presentation was 8.35 mm (range 5-22 mm). Seven patients had a syrinx at presentation. The syrinx size did not change in these patients on follow-up imaging studies. No new syrinxes developed in the remaining patients who underwent subsequent imaging. The total number of patients with presenting symptoms was 81. Of those 81 patients, 67 demonstrated symptoms that were not typical of CM-I. Of the 14 patients with symptoms attributed to CM-I, 9 had symptoms that were not severe or frequent enough to warrant surgery, and surgery was recommended in the remaining 5 patients. Chiari malformation Type I was also diagnosed in 43 asymptomatic patients who had imaging studies performed for various reasons. No new neurological deficits were noted in any patient for the duration of follow-up.

CONCLUSIONS

The majority of patients with CM-I who are followed up without surgery do not progress clinically or radiologically. Longer follow-up of this cohort will be required to determine if symptoms or new neurological findings develop over the course of many years.

Chiari type I malformation, syncope, headache, hypoglycemia and hepatic steatosis in an 8-year old girl: a causal association?

Chiari type I malformation (CMI) is a congenital hindbrain anomaly characterized by downward displacement of the cerebellar tonsils through the foramen magnum. Chiari type I malformation often presents with a complex clinical picture and can be sporadic or linked to a variety of genetic conditions. We report on a girl in whom Chiari type I malformation was associated with hypoglycemia, headache, vertigo, syncope and hepatic steatosis. We hypothesize that these symptoms are primarily a consequence of Chiari type I malformation.

Chiari type I malformation in a pediatric population

The natural history of Chiari I malformation in children remains unclear. A population-based retrospective cohort study was therefore conducted. Radiology reports from all head and spine magnetic resonance imaging scans (n = 5248) performed among 741,815 children under age 20 within Kaiser Northern California, 1997-1998, were searched for Chiari I. Medical records and imaging studies were reviewed to determine clinical and radiographic predictors of significant neurologic symptoms, defined as moderate to severe headache, neck pain, vertigo, or ataxia. The 51 patients identified with Chiari I represented 1% of the children who had head or spine magnetic resonance imaging scans performed during the study period. Headache (55%) and neck pain (12%) were the most common symptoms. Syringomyelia was present in 6 patients (12%) at initial diagnosis; no new syrinxes developed during follow-up. Older age at time of diagnosis was associated with increased risk of headache (odds ratio OR = 1.3, 95% confidence interval CI = 1.1-1.5) and significant neurologic symptoms (OR = 1.2, 95% CI = 1.04-1.4). Chiari I, an underrecognized cause of headaches in children, is also frequently discovered incidentally in children without symptoms. Larger and longer-term studies are needed to determine the prognosis and optimal treatment of pediatric Chiari I.

Decompression for Chiari type I-malformation (with or without syringomyelia) by extreme lateral foramen magnum opening and expansile duraplasty with arachnoid preservation: comparison with other technical modalities (Literature review)

Posterior craniocervical decompression is the procedure most currently used for treating Chiari I malformation (alone or in association with syringomyelia in the absence of hydrocephalus). We reviewed the various technical modalities reported in the literature. We present a personal series of 44 patients harboring Chiari type I malformation (CM-I) operated with a suboccipital craniectomy and a C1 (or C1/C2) laminectomy, plus an extreme lateral Foramen Magnum opening, a "Y" shaped dural incision with preservation of the arachnoid membrane, and an expansile duraplasty employing autogenous periosteum. Outcomes were analyzed with follow-up ranging from 1 to 10 years (4 years on average). The presented technique was compared with the other surgical modalities reported in the literature. This comparative study shows that this type of craniocervical decompression achieved the best results with minimal complications and side-effects. Syringomyelia associated with CM-I must be treated by craniocervical decompression alone. Shunting no longer appears to be an appropriate method of treatment for syringomyelia.

The natural history of the Chiari Type I anomaly

OBJECT

Since the advent of MR imaging, an increasing number of asymptomatic or oligosymptomatic patients have been diagnosed with Chiari malformation Type I (CM-I). The decision of whether or not to operate is more difficult in these patients than in those with clear symptoms because of the lack of information about the natural course of this disease.

METHODS

The authors report on their experience in a series of 22 patients with CM-I who were evaluated at the authors' institution, and for whom a conservative approach to treatment was adopted. The patients ranged in age from 1 to 16 years (mean 6.3 years) at diagnosis. Neuroradiological and complete clinical examinations were performed in all patients 6 months after the first observation and every year thereafter. The follow-up period ranged from 3 to 19 years (mean 5.9 years).

RESULTS

Chiari malformation Type I was incidentally detected on MR images in 11 of 22 patients. The remaining 11 patients had minimal clinical signs at presentation that were not regarded as necessitating immediate surgical treatment. Seventeen patients (77.3%) showed progressive improvement in their symptoms or remained asymptomatic at the last follow-up whereas 5 patients (22.7%) experienced worsening, which was mild in 2 cases and required surgical correction in the remaining 3 cases. On MR imaging a mild reduction in tonsillar herniation was appreciated in 4 patients (18.18%), with complete spontaneous resolution in 1 of these. In 16 patients, tonsillar herniation remained stable during follow-up.

CONCLUSIONS

The authors' data confirm the common impression that in both asymptomatic and slightly symptomatic patients with CM-I, a conservative approach to treatment should be adopted with periodic clinical and radiological examinations.

Time course of syringomyelia resolution following decompression of Chiari malformation Type I

OBJECT

To better understand syrinx pathophysiology, the authors performed a prospective study in which they used findings from serial clinical and magnetic resonance (MR) imaging examinations performed before and after craniocervical decompression to establish the time course of syrinx narrowing.

METHODS

Serial clinical examinations and cervical MR imaging were performed in 29 consecutive patients with Chiari malformation Type I (CM-I) and syringomyelia before surgery, 1 week, and 3-6 months after surgery, and then annually. Time to narrowing of the syrinx (>50% decrease in maximal anteroposterior diameter) following surgery was calculated using the Kaplan-Meier method.

RESULTS

All syringes decreased in diameter and length (number of segments) on MR images at 3-6 months, 1 year, and 2 years or later. The syrinx diameter decreased from 6.9+/-2.1 mm (mean+/-standard deviation) preoperatively to <1.5 mm at last evaluation (p<0.0001). The median time to syrinx narrowing was 3.6 months following CM-I decompression (95% confidence interval 3.0-6.5 months). After surgery 94% of patients had improved symptoms, but symptoms resolved incompletely in 68% of patients; 52 and 59% of patients had residual dysesthesias and sensory loss, respectively. Clinical improvement occurred before partial or complete disappearance of the syrinx on MR images. Patient age, duration of symptoms, sex, preoperative syrinx diameter, and length of syrinx were unrelated to time to syrinx narrowing.

CONCLUSIONS

Most patients improve after decompression for CM-I, but many have residual symptoms. Syringes may continue to diminish for months to years after surgical decompression. A collapsed syrinx (absence of distention of the spinal cord) indicates that the pathophysiology has been reversed by treatment regardless of the completeness of elimination of the cavity on MR images.

The post-syrinx syndrome: stable central myelopathy and collapsed or absent syrinx

Among 168 cases with neurologic findings of cervicothoracic syringomyelia and MRI findings of Chiari 1 malformation and/or underdevelopment of the posterior cranial fossa, 15 patients (9.1 %) had collapsed, flat syrinxes and 14 patients (8.3 %) did not have syrinxes. Both groups of patients had clinical findings of central myelopathy that had been stable for at least 3 years. Magnetic resonance imaging detected atrophy of the cervical spinal cord in both groups and spontaneous communications between the syrinx and the subarachnoid space in 3 patients of the group with collapsed syrinxes. Analysis of these results and review of the literature suggest that patients with clinical signs of syringomyelia and Chiari 1 malformation or underdeveloped posterior fossa, but with small or absent syringomyelitic cavities, have the "postsyrinx" state as a result of spontaneous collapse of distended syrinxes.

International survey on the management of Chiari I malformation and syringomyelia

INTRODUCTION

The availability of magnetic resonance imaging (MRI) has resulted in an increasing number of asymptomatic, minimally symptomatic, and doubtfully symptomatic patients being diagnosed with a Chiari I malformation with or without syringomyelia. In an attempt to clarify how neurosurgeons manage these clinical problems, an international survey on the Chiari I malformation and related syringomyelia was undertaken.

METHOD

A questionnaire on the expected natural course of the disease and on aspects of the surgical technique for a number of hypothetical cases relating to Chiari I malformation with and without syringomyelia was used to survey Pediatric Neurosurgeons worldwide.

RESULTS

Of 246 questionnaires distributed, 76 (30.8%) were completed and returned. There was a consensus that no operation should be carried out in asymptomatic patients with a Chiari I malformation, unless there is associated syringomyelia. There was a consensus that decompression of the Chiari malformation should be performed in patients with scoliosis when syringomyelia is present, and the majority decompressed the Chiari malformation in scoliotic patients even in the absence of syringomyelia. Suboccipital decompression was the standard surgical procedure for Chiari I malformations. The majority of respondents favored routine dural opening at surgery and closure with a pericranial or synthetic patch graft. In the case of a persistent or progressive syrinx after suboccipital decompression, the majority recommended shunting of the syrinx to the subarachnoid space or to the pleural cavity.

CONCLUSION

There continues to be much variation in the management of the Chiari I malformation.