Surgical treatment of syringomyelia based on magnetic resonance imaging criteria

Long-Term Impairment of the Blood-Spinal Cord Barrier in Patients With Post-Traumatic Syringomyelia and its Effect on Prognosis

STUDY DESIGN

Cohort study.

OBJECTIVE

The aim of this study was to explore the association between blood-spinal cord barrier (BSCB) markers and other factors associated with an unfavorable outcome among patients with post-traumatic syringomyelia (PTS) who achieved successful intradural adhesion lysis (IAL).

SUMMARY OF BACKGROUND DATA

Only approximately half of PTS patients receiving IAL have a favorable outcome.

PATIENTS AND METHODS

Forty-six consecutive patients with PTS and 19 controls (CTRL) were enrolled. All PTS patients underwent physical and neurological examinations and spinal magnetic resonance imaging before and 3 to 12 months after IAL. All patients underwent myelography before surgery. BSCB disruption was detected by increased intrathecal and serum concentrations of albumin, immunoglobulin (Ig)G, IgA, and IgM. A multivariable analysis was performed with a logistic regression model to identify factors associated with unfavorable outcomes. Receiver operating characteristic curves were calculated to investigate the diagnostic value of biomarkers.

RESULTS

The ages and general health of the PTS and CTRL groups did not differ significantly. QAlb, IGAQ, IGGQ, and IGMQ was significantly higher in PTS patients than in controls ( P =<0.001). The degree of intradural adhesion was significantly higher in the unfavorable outcome group than in the favorable outcome group ( P <0.0001). QAlb, immunoglobulin (Ig)AQ, IGGQ, and IGMQ was significantly correlated with clinical status ( R =-0.38, P <0.01; R =-0.47, P =0.03; R =-0.56, P =0.01; R =-0.43, P =0.05, respectively). Higher QAlb before surgery (odds ratio=2.66; 95% CI: 1.134-6.248) was significantly associated with an unfavorable outcome. The receiver operating characteristic curve analysis demonstrated a cutoff for QAlb higher than 10.62 with a specificity of 100% and sensitivity of 96.3%.

CONCLUSION

This study is the first to detect increased permeability and BSCB disruption in PTS patients. QAlb>10.62 was significantly associated with unfavorable clinical outcomes following intradural decompression.

LEVEL OF EVIDENCE

Level III-prognostic.

Risk of meningitis after posterior fossa decompression with duraplasty using different graft types in patients with Chiari malformation type I and syringomyelia: a systematic review and meta-analysis

Several complications have been reported after the use of grafts for duraplasty following posterior fossa decompression for the treatment of Chiari malformation type I. This study aims to investigate the rate of meningitis after posterior fossa decompression using different types of grafts in patients with Chiari malformation type I and associated syringomyelia. The search was conducted using multiple databases, including PubMed, Scopus, Web of Science, and Embase. Data on the rate of meningitis, syrinx change, and rate of reoperation were extracted and investigated. Quality of evidence was assessed using the Newcastle-Ottawa scale. Nineteen studies were included in the final meta-analysis, encompassing 1404 patients and investigating autografts, synthetic grafts, allografts, and xenografts (bovine collagen, bovine pericardium, and pig pericardium). Autografts were associated with the lowest rate of meningitis (1%) compared to allografts, synthetic grafts, and xenografts (2%, 5%, and 8% respectively). Autografts were also associated with the lowest rate of reoperation followed by xenografts, allografts, and synthetic grafts (4%, 5%, 9%, and 10% respectively). On the other hand, allografts were associated with the highest rate of syrinx improvement (83%) in comparison to autografts and synthetic grafts (77%, and 79% respectively). Autografts were associated with the lowest meningitis, reoperation, and syrinx improvement rates. Furthermore, synthetic grafts were associated with the highest reoperation and xenografts with the highest rate of meningitis, whereas allografts were associated with the best syrinx improvement rate and second-best meningitis rate. Future studies comparing autografts and allografts are warranted to determine which carries the best clinical outcome.

Neurological deterioration after posterior fossa decompression for adult syringomyelia: Proposal for a summarized treatment algorithm

Background

Patients with syringomyelia who present with new neurological symptoms after posterior fossa decompression (PFD) are not uncommon. However, systematic reports on different pathologies are few in the literature.

Objective

The purpose of this study was to summarize our experience for failed PFD.

Methods

Between January 2015 and December 2019, 85 consecutive failed PFD patients were identified. The neurological courses were summarized with Klekamp J (KJ) or mJOA score system for all patients. Long-term results were summarized with Kaplan-Meier method.

Results

Twenty-eight consecutive patients underwent FMDD (Foramen magnum and foramen of Magendie dredging) (Group I), extradural PFD and manipulation of tonsil was significantly associated with lower failure rates. Twenty patients underwent craniocervical fixation (Group II), nine underwent local spinal segment decompression (Group III), six underwent CSF diversion procedures, and one were treated for persistent pain by radiofrequency. Neuropathic pain was most significantly improved in Group I while swallowing improved in Group II within 1 year after the surgery. In the long term, late postoperative deterioration-free possibility in Group II was better than in Group I. All patients in Group III improved (P = 0.0088). Six cases of CSF diversion procedures were relieved in a short time. Pain in one patient persisted after PFD, and trial of radiofrequency failed.

Conclusion

Not only does the recurrent cerebrospinal fluid flow obstruct the foramen magnum, but also spinal pathologies and craniocervical instabilities may occur. This study provides the largest summarized clinical experience that may assist surgeons with different therapeutic decisions for failed PFD.

Theco-thecal bypass technique elucidating a novel procedure and perspective on treatment of post-arachnoiditis syringomyelia: A case report

BACKGROUND

Post-arachnoiditis syringomyelia is a condition in which there is an intraspinal cerebrospinal fluid (CSF) blockade due to arachnoidal adhesions and bands. Although many of the techniques currently in use, namely, the theco-peritoneal, syringo-pleural, syringo-peritoneal, and syringo-subarachnoid shunts, are effective, the results are often variable.

CASE SUMMARY

A 36-year-old man with a past history of pulmonary tuberculosis, presented with progressive paraesthesia in the feet and progressive paraparesis along with constipation, difficulty in micturition, and decreased libido. He was bedridden a month before presentation. Magnetic resonance imaging revealed a dorsal multiloculated syrinx from D3-D10 vertebral levels. He underwent a D1-2 to D11 theco-thecal shunt bilaterally to abolish the CSF gradient across the level of the syrinx. There was no direct surgical handling of the spinal cord involved. At the 15-mo follow up, the patient had significant improvement in his symptoms and function.

CONCLUSION

We present a novel technique aimed at correcting the primary cause of a post-arachnoiditis syrinx, the subarachnoid cerebrospinal flow obstruction or block, which we believe is simple and effective, involves minimal handling of the normal neural structures, and attempts to restore the physiology of CSF flow across the obstruction, with favorable clinical results.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Endoscopic third ventriculostomy for treatment of tonsillar descent with hydrocephalus: CSF flow dynamics and treatment strategies

OBJECTIVE

To explore the role of cerebrospinal fluid (CSF) flow dynamics and develop treatment strategies involving endoscopic surgery for tonsillar descent with hydrocephalus.

METHODS

This study included 15 patients with tonsillar descent with hydrocephalus. All patients underwent cine-magnetic resonance imaging (MRI) preoperatively to measure CSF flow at the entrance of the cerebral aqueduct and foramen of Magendie. Endoscopic third ventriculostomy (ETV) was performed.

RESULTS

All patients exhibited abnormal CSF flow dynamics at Magendie's foramen prior to surgery. After surgery, cine-MRI showed CSF flow through the ventriculostomy. During the follow-up period of 8-72 months, the level of tonsillar descent reduced in 9 patients, and the spinal cord syrinx was reduced in 1 patient. Clinical symptoms were improved in 14 patients. Secondary endoscopically assisted posterior cranial fossa decompression was performed in one patient whose symptoms were not improved after ETV. In no case was secondary ventriculo-peritoneal shunting performed following primary ETV.

CONCLUSION

ETV is a low-risk and effective method that can replace ventriculo-peritoneal shunt placement in the treatment of tonsillar descent with obstructive hydrocephalus. Preoperative cine-MRI of CSF flow dynamics in the aqueduct and Magendie's foramen provides valuable information for determining surgical timing and strategies.

Neuropathic Arthropathy of the Shoulder: A Systematic Review of Classifications and Treatments

BACKGROUND

Neuropathic arthropathy of the shoulder is a chronic progressive process characterized by joint destruction in the presence of a neurosensory deficit. Causes include syringomyelia, syphilis, diabetes, chronic alcoholism, and leprosy, with syringomyelia accounting for the vast majority of upper-extremity Charcot joints. Early presentation of this rare condition includes nonspecific symptoms such as swelling, erythema, sensory symptoms, and decreased functionality, making diagnosis challenging.

METHODS

We systematically reviewed 32 case reports published between 1924 and 2016. A total of 59 shoulders from 56 patients are included in this analysis. Variables include patient demographic characteristics, presentation, etiology, diagnostic techniques, treatment, outcome, and follow-up of Charcot shoulder.

RESULTS

We compiled a total of 25 right shoulders (42%), 24 left shoulders (41%), and 10 shoulders (17%) with unspecified laterality. The mean patient age (and standard deviation) was 49 ± 11 years, and the median age was 47 years. There was a higher prevalence in men (37 shoulders [63%]) compared with women (22 shoulders [37%]). Presenting symptoms included reduced range of motion (53 shoulders [90%]), paresthesia or hypoesthesia (45 [76%]), swelling (44 [75%]), weakness (40 [68%]), pain (31 [53%]), and reduction in deep tendon reflexes (22 [37%]). Shoulder radiographs were made in all cases. The presence of a syrinx was detected in 45 shoulders (76%) with magnetic resonance imaging, myelography, or clinical diagnosis. Sixteen shoulders (27%) reported exposure to trauma, with a 69% decrease in time from presentation to diagnosis compared with non-traumatic cases. Treatment was categorized as solely nonoperative management (14 [24%]), operative management (13 [22%]), combined therapy (20 [34%]), and no treatment listed (10 [17%]). Two surgical cases (3%) were excluded from our treatment group analysis as they were treated for unrelated or misdiagnosed conditions.

CONCLUSIONS

Our study increases awareness and understanding of this complex, progressive disease to reduce delay and misdiagnosis and to contribute to the standard-of-care recommendations.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Appropriate surgical procedures for Chiari type 1 malformation and associated syrinx based on radiological characteristics of the craniovertebral junction

Several surgical procedures can be applied for syrinx associated with Chiari type 1 malformation; however, it remains controversial as to which approach is the most effective. Here, we evaluated the indications and limitations of foramen magnum decompression (FMD) with or without dural plasty. Forty patients with Chiari type 1 malformation were surgically treated and followed up for > 12 months. Thirty-two patients (80.0%) underwent FMD with removal of only the outer dura mater layer, while eight patients underwent FMD with dural plasty. We evaluated surgery-related complications and preoperative radiological findings affecting syrinx shrinkage rates. Post-surgery, the mean syrinx shrinkage rates were 0.32 ± 0.44 in the outer layer-removal group and 0.72 ± 0.27 in the dural plasty group (P = 0.012). Surgery-related complications were less frequent, but reoperation was more frequent, in the outer layer-removal group. The extent of tonsillar descent significantly affected syrinx shrinkage in FMD with outer layer removal (P = 0.042). The outcomes of both approaches in patients with tonsillar descent < 10.0 mm were similar. The dura mater in the posterior fossa was thin, necessitating dural plasty with FMD, while the spinal dura was sufficiently thick for removal of the outer layer in the Chiari patients. These histological differences corresponded with the inferior margin of the cerebellar tonsil. Recognizing the appropriate surgical indication for achieving good post-procedural outcomes is necessary for reducing complications and improving outcomes of FMD for Chiari type 1 malformations.

Interval Recovery of Syringomyelia in Chiari I Malformation Patient with Acute Cervical Trauma After Anterior Decompression: Case Report and Review of Literature

BACKGROUND

Syringomyelia in the cervical spinal cord is a complex pathology that is commonly associated with Chiari I malformation or spinal cord trauma. In both cases the development of syringomyelia has been linked to multiple anatomic and molecular elements including epidural compression. Literature has mainly reported posterior cervical decompressive procedures or shunting of the cyst as options to address this pathology. Anterior decompression is rarely recommended.

CASE DESCRIPTION

We present the case of a 19-year-old female who suffered a motor vehicle accident causing a cervical subluxation with mild new-onset neurologic deficits. Preoperative workup showed a large incidental cervical syringomyelia associated with a Chiari I malformation. Anterior cervical decompression at the subluxated cervical segment with a concomitant anterior and posterior fusion was performed. Postoperative workup revealed a significant interval reduction in the size of the syrinx cavity with concomitant neurologic improvement.

CONCLUSIONS

Anterior decompression may be considered as an option in select cases of syringomyelia. The findings of this case support the theory of epidural compression as one of the inciting events for the development of syringomyelia.

The addition of duraplasty to posterior fossa decompression in the surgical treatment of pediatric Chiari malformation Type I: a systematic review and meta-analysis of surgical and performance outcomes

OBJECTIVE Surgery is the definitive treatment of Chiari malformation Type I (CM-I). It involves posterior fossa decompression, which can be performed along with C-1 laminectomy, reconstructive duraplasty, or tonsil shrinkage. The aim of this study was to provide an updated systematic review and meta-analysis of the latest available evidence regarding posterior fossa decompression only (PFDO) versus posterior fossa decompression with duraplasty (PFDD) in the treatment of CM-I in children. METHODS A literature search was performed in compliance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for article identification, screening, eligibility, and inclusion. Relevant articles were identified from 6 electronic databases from their inception to April 2016. These articles were screened against established criteria for inclusion into this study. RESULTS From 12 relevant studies identified, 1492 pediatric patients treated via PFDD were compared with 1963 pediatric patients treated by PFDO for CM-I. PFDD was associated with greater overall clinical improvement (p = 0.009), along with longer length of stay (p < 0.0001) and more postoperative complications (p = 0.0001) compared with PFDO. No difference was observed between PFDD and PFDO in terms of revision surgery incidence (p = 0.13), estimated blood loss (p = 0.14), syrinx improvement (p = 0.09), or scoliosis improvement (p = 0.95). CONCLUSIONS It appears that the addition of duraplasty to posterior decompression in the definitive treatment of CM-I in children may alter surgical and performance outcomes. In particular, parameters of overall clinical improvement, length of stay, and postoperative complication may differ between children undergoing PFDD and those undergoing PFDO. Current evidence in the literature is of low to very low quality that, as of yet, has not been able to completely control for inherent selection bias both in study design and surgeon preference. Future, large prospective registries and randomized controlled trials are warranted to validate the findings of this study.

"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.

Pediatric and adult Chiari malformation Type I surgical series 1965-2013: a review of demographics, operative treatment, and outcomes

OBJECT

Chiari malformation Type I (CM-I) is a hindbrain disorder associated with elongation of the cerebellar tonsils, which descend below the foramen magnum into the spinal canal. It occurs in children and adults. Clinical symptoms mainly develop from alterations in CSF flow at the foramen magnum and the common subsequent development of syringomyelia.

METHODS

The authors reviewed English-language reports of pediatric, adult, and combined (adult and pediatric) surgical series of patients with CM-I published from 1965 through August 31, 2013, to investigate the following: 1) geographical distribution of reports; 2) demographics of patients; 3) follow-up lengths; 4) study durations; 5) spectrum and frequency of surgical techniques; 6) outcomes for neurological status, syrinx, and headache; 7) frequency and scope of complications; 8) mortality rates; and 9) differences between pediatric and adult populations. Research and inclusion criteria were defined, and all series that contained at least 4 cases and all publications with sufficient data for analysis were included.

RESULTS

The authors identified 145 operative series of patients with CM-I, primarily from the United States and Europe, and divided patient ages into 1 of 3 categories: adult (>18 years of age; 27% of the cases), pediatric (≤18 years of age; 30%), or unknown (43%). Most series (76%) were published in the previous 21 years. The median number of patients in the series was 31. The mean duration of the studies was 10 years, and the mean follow-up time was 43 months. The peak ages of presentation in the pediatric studies were 8 years, followed by 9 years, and in the adult series, 41 years, followed by 46 years. The incidence of syringomyelia was 65%. Most of the studies (99%) reported the use of posterior fossa/foramen magnum decompression. In 92%, the dura was opened, and in 65% of these cases, the arachnoid was opened and dissected; tonsillar resection was performed in 27% of these patients. Postoperatively, syringomyelia improved or resolved in 78% of the patients. Most series (80%) reported postoperative neurological outcomes as follows: 75% improved, 17% showed no change, and 9% experienced worsening. Postoperative headaches improved or resolved in 81% of the patients, with a statistical difference in favor of the pediatric series. Postoperative complications were reported for 41% of the series, most commonly with CSF leak, pseudomeningocele, aseptic meningitis, wound infection, meningitis, and neurological deficit, with a mean complication rate of 4.5%. Complications were reported for 37% of pediatric, 20% of adult, and 43% of combined series. Mortality was reported for 11% of the series. No difference in mortality rates was seen between the pediatric and adult series.

CONCLUSIONS

Before undergoing surgical treatment for CM-I, symptomatic patients and their families should be given clear information about the success of treatment and potential complications. Furthermore, surgeons may benefit from comparing published data with their own. In the future, operative CM-I reports should provide all details of each case for the purpose of comparison.

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

OBJECT

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Long-term results after posterior fossa decompression in syringomyelia with adult Chiari Type I malformation

Object

There is little information about the long-term effectiveness and complications following decompressive surgery for syringomyelia related to Chiari malformation Type I (CM-I).

Methods

Examining long-term clinical and radiological follow-up, the authors studied a mixed retrospective and prospective single-institution cohort of 109 consecutive surgically treated adult patients with syringomyelia and CM-I. All patients underwent a standardized surgical protocol: decompression of the craniocervical junction, arachnoid exploration, and shrinkage of the cerebellar tonsils. Factors predicting outcome were investigated.

Results

The retrospective arm consisted of 41 cases treated between 1990 and 1994, and the prospective arm comprised 68 patients treated between 1994 and 2001. The mean overall age was 45.9 years, and 58.8% of the population was female. The median follow-up period was 12.7 years. The most frequent initial symptoms were pain and sensory and gait disturbances. There was no perioperative death or neurological deterioration. The comprehensive perioperative complication rate was approximately 11%, with 3 cases (2.7%) of CSF leakage. Regression analysis showed that the best combination of clinical and radiological outcome predictors was age and duration of symptoms. Clinical follow-up confirmed surgical result stability with clinical improvement of greater than 90% of the spinal and cranial manifestations over a long-term period. Two patients had radiological recurrences of syringomyelia without clinical signs 85 and 124 months after surgery.

Conclusions

Certain clinical predictors of poor clinical and radiological prognosis were identified—namely, age at time of surgery and symptom duration. The results of the study provide additional long-term data that support the effectiveness and safety of relieving CSF block at the craniocervical junction in CM-I–related syringomyelia.

Syrinx resolution after posterior fossa decompression in patients with scoliosis secondary to Chiari malformation type I

INTRODUCTION

Description of syrinx resolution after posterior fossa decompression (PFD) in patients with scoliosis secondary to Chiari malformation type I (CMI) and syringomyelia (SM) has been rarely reported in the literature. This study was performed to investigate the outcome of PFD in patients with scoliosis secondary to CMI and to identify potential predictive factors for better outcome after PFD.

MATERIAL AND METHODS

Patients with scoliosis secondary to CMI and SM, who had undergone PFD during the period 2000 through 2009, were recruited. Inclusion criteria were (1) age ≤ 18 years, (2) diagnosis of SM associated with CMI, (3) scoliosis as the first complaint, (4) having undergone preoperative and follow-up magnetic resonance imaging (MRI). Patients with acquired CMI anomalies or who had received syringosubarachnoid shunting were excluded. The maximal S/C ratio and syrinx length were measured to evaluate syrinx resolution after PFD. A 20% decrease in S/C ratio or length at the latest follow-up was defined as a significant radiographic improvement and complete resolution was used to describe the syrinx disappearing after PFD.

RESULTS

44 patients were recruited. Follow-up MRI was conducted for all 44 patients at 6 ± 3 months postoperatively, for 37 patients at 2 years ± 3 months, for 26 patients at 4 years ± 3 months, and for 15 patients at 6 years ± 3 months. 97.7% (43 of 44) of patients showed significant radiographic improvement by MRI. The distance of tonsillar descent (mm) was correlated significantly with the surgical outcome (r = 0.116, P = 0.013). Significant improvement was observed within 6 months postoperatively, with continued slow improvement after that.

CONCLUSION

Syringes showed significant improvement after PFD in most patients with scoliosis secondary to CMI. Resolution generally occurred within 6 months follow-up and continued at a slow rate for several years. In addition, the severity of tonsillar descent is a potential predictor for better improvement after standard PFD.

Institutional experience with 500 cases of surgically treated pediatric Chiari malformation Type I

OBJECT

The diagnosis and treatment of Chiari malformation Type I (CM-I) has evolved over the last few decades. The authors present their surgical experience of over 2 decades of treating children with this form of hindbrain herniation.

METHODS

The authors conducted a retrospective review of their institutional experience with the surgical treatment of the pediatric CM-I from 1989 to 2010.

RESULTS

The 2 most common presentations were headache/neck pain (40%) and scoliosis (18%). Common associated diagnoses included neurofibromatosis Type 1 (5%) and idiopathic growth hormone deficiency (4.2%). Spine anomalies included scoliosis (18%), retroversion of the odontoid process (24%), Klippel-Feil anomaly (3%), and atlantooccipital fusion (8%). Approximately 3% of patients had a known family member with CM-I. Hydrocephalus was present in 48 patients (9.6%). Syringomyelia was present in 285 patients (57%), and at operation, 12% of patients with syringomyelia were found to have an arachnoid veil occluding the fourth ventricular outlet. Fifteen patients (3%) have undergone reoperation for continued symptoms or persistent large syringomyelia. The most likely symptoms and signs to resolve following surgery were Valsalva-induced headache and syringomyelia. The average hospital stay and "return to school" time were 3 and 12 days, respectively. The follow-up for this group ranged from 2 months to 15 years (mean 5 years). Complications occurred in 2.4% of cases; there was no mortality. No patient required acute return to the operating room, and no blood transfusions were performed.

CONCLUSIONS

The authors believe this to be the largest reported series of surgically treated pediatric CM-I patients and hope that their experience will be of use to others who treat this surgical entity.

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

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

Shunt malfunction causing acute neurological deterioration in 2 patients with previously asymptomatic Chiari malformation Type I. Report of two cases

Patients with symptomatic Chiari malformation Type I (CM-I) typically exhibit a chronic, slowly progressive disease course with evolution of symptoms. However, some authors have reported acute neurological deterioration in the setting of CM-I and acquired Chiari malformations. Although brainstem dysfunction has been documented in patients with CM-II and hydrocephalus or shunt malfunction, to the authors' knowledge only 1 report describing ventriculoperitoneal (VP) shunt malfunction causing neurological deterioration in a patient with CM-I exists. The authors report on their experience with the treatment of previously asymptomatic CM-I in 2 children who experienced quite different manifestations of acute neurological deterioration secondary to VP shunt malfunction. Presumably, VP shunt malfunction created a positive rostral pressure gradient across a stenotic foramen magnum, resulting in tetraparesis from foramen magnum syndrome in 1 patient and acute ataxia and cranial nerve deficits from syringobulbia in the other. Although urgent shunt revisions yielded partial recovery of neurological function in both patients, marked improvement occurred only after posterior fossa decompression.

Factors contributing improvement of syringomyelia and surgical outcome in type I Chiari malformation

OBJECTIVE

The aim of our study was to compare pre- and postoperative radiologic data of posterior fossa and the improvement of syringomyelia after posterior fossa decompression (PFD) with and without tonsillar management in Chiari type capital I, Ukrainian malformation (CM-I).

MATERIAL AND METHODS

A retrospective analysis was made of all patients who underwent PFD between Oct 1991 and March 2007 for CM-I. Fifty-seven patients treated for CM-I at a single institution were included in the study. Patients were divided into two groups according to the procedures used during their PFD: PFD vs. PFD with tonsillar management. To determine whether the tonsillar management or changes of posterior fossa volume relate with surgical outcome, we measure posterior fossa size and syringomyelia pre- and postoperatively using magnetic resonance imaging.

RESULTS

Forty patients (70.2%) received PFD and 17 patients (29.8%) received PFD with tonsillar management. The length of syringomyelia affected improvement of syringomyelia (alteration rate, A-rate). Clinical symptoms, craniectomy size, syringomyelia type, and the surgeon's specialty did not affect A-rate. Tonsillar management has no significant effect on improvement of syringomyelia. Four patients need repeated surgery due to recurrence.

CONCLUSION

We have shown that tonsillar management do not lead to improve A-rate, and the radiologic changes of posterior fossa volume do not relate with radiologic improvement of syringomyelia. PFD without tonsillar management is sufficient to improve syringomyelia. The longer syrinx, the more A-rate improve in our study. However, a wider craniectomy is unrelated to A-rate. In cases of recurrent patients, we obtained good results with tonsillar management or syringosubarachnoid shunt.

The vanishment of an intramedullary high-signal intensity lesion at the craniocervical junction after surgical treatment: a case report of the presyrinx state

STUDY DESIGN

A case report of the presyrinx state at the craniocervical junction with vanishment of an intramedullary high-signal lesion followed by decompression and fixation.

OBJECTIVE

To report the reversible change of an intramedullary high-signal lesion on T2-weighted MRI as a presyrinx state.

SUMMARY OF BACKGROUND DATA

The pathology of a T2-weighted high-signal intensity area in the spinal cord has not yet been described in detail. The case presented here showed the vanishment of this lesion after the surgical procedure, which implies that some high-signal intensity lesions might be reversible as a presyrinx state.

METHODS

A 75-year-old man presented with severe cervical myelopathy. Neurologic findings and observations on various images indicated compression myelopathy due to both a pseudotumor at the craniocervical junction and spondylosis at C3-C4 disc level due to Klippel-Feil syndrome. The most obvious finding was a vast high-signal intensity lesion at the craniocervical junction, which was speculated to be a syringomyelia before surgery.

RESULTS

The MRI at 1 month after surgical treatment (occipito-spinal fusion with the decompression by enlargement of foramen magnum) revealed complete vanishment of the vast high intensity lesion at the craniocervical junction, which remained undetected at the 2 years and 8 months follow-up and corresponded with improvement in the clinical symptoms of myelopathy.

CONCLUSION

The vanishment of these signal changes on MRI after surgery was interpreted as a presyrinx state, demonstrating this reversible pathology in the spinal cord.

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.

Electrophysiologic and clinical data support the use of dorsal root entry zone myelotomy in syringosubarachnoid shunting for syringomyelia

BACKGROUND

The objectives of this study were to correlate preoperative changes in SEPs with clinical sensory dysfunction and to establish their importance in planning the microsurgical approach, either by DM myelotomy or by DREZ myelotomy, for patients with syringomyelia.

METHODS

In addition to conducting clinical sensory examination, we evaluated the N13 potential after median nerve stimulation and CPs after tibial nerve stimulation intraoperatively before performing myelotomy on patients with syringomyelia (N = 14).

RESULTS

Eleven patients with intact DS presented with unilateral PTD, and 9 had distressing unilateral dermatomal pain. Deep sensibility was affected in 3 patients (bilaterally in 1 patient) without PTD. Patients with PTD were likely to have spontaneous pain (P = .005). A significant correlation between preoperative PTD and the absence of the N13 potential was demonstrated on the right (P = .015) and left (P = .004) sides. In patients with PTD, DREZ myelotomy on the symptomatic side is suggested as the treatment of choice, whereas DM myelotomy might be superior in patients without PTD.

CONCLUSIONS

Absence of pain or temperature sensation in patients with syringomyelia is usually accompanied by same-sided loss of the N13 potential, suggesting damage to the DH gray matter. Deep sensibility is typically normal, and DREZ myelotomy with preservation of DCs is proposed as the treatment of choice. Conducted potentials are usually distorted in patients with normal pain or temperature sensation and affected vibration and posture sensation, suggesting damage to DCs and making DM myelotomy the treatment of choice. Electrophysiologic and clinical data support the use of DREZ myelotomy in syringosubarachnoid shunting for syringomyelia in patients whose DCs have an intact function.

Post-traumatic syringomyelia producing paraplegia in an infant

BACKGROUND

Post-traumatic syringomyelia is described in adults after spinal trauma but extremely rarely seen in children, especially in the first year of life.

MATERIALS AND METHODS

We describe a boy who, at the age of 7 months, suffered spinal trauma during a car accident when he was held at his mother's lap and suffered extreme flexion of his torso. He suffered a mid-shaft fracture of his right femur, treated with hip spica for 6 weeks. After removal of the spica, it was noticed that he was not moving his legs, but he had preserved pain sensation in the lower half of his trunk and legs. A spine magnetic resonance scan performed 2 months after the injury showed a compressed wedge fracture of the body of T5 vertebra, kyphosis and a large syringomyelia cavity extending from T4 to T8. He had two operations to control the syringomyelia with laminotomy-laminoplasty, dissection of the arachnoid adhesions initially and drainage of the cavity on the second operation, with only modest success. He remains paraplegic 7 years after the injury. He has received thoracic brace immediately after the first spinal operation, which avoided kyphosis.

DISCUSSION

Spinal trauma is rare in the first year of life; hence, post-traumatic syringomyelia is very rarely seen in infants. Nevertheless, it should be suspected after a major trauma, in the presence of paraplegia. Surgical treatment of post-traumatic syringomyelia in young children has the additional consideration of post-laminotomy kyphosis; hence, thoracic brace should be used early.

Mini-Invasive Surgery for Chiari Type I Malformation

Surgical treatment of Chiari I malformation and associated syringomyelia includes several different techniques with various degrees of invasiveness. Most extensive procedures may provide good long-term outcome in a good proportion of cases but are burdened by a quite high risk of postoperative complications. Thirty children operated on by simple bone decompression are retrospectively reviewed to assess the effectiveness of a less invasive technique. The present series comprises 30 children (18 females, 12 males; mean age: 68 months) treated from 1993 to 2005. All patients underwent foramen magnum decompression by means of suboccipital craniectomy and resection of the fibrous band at the level of foramen itself. Twenty-one children also required C1 laminectomy while a dural delamination was performed in 11 cases. The mean current follow-up is 4.3 years (1–12.6 years). Head and/or neck pain was the most frequent preoperative finding (56.7%), followed by upper and lower extremity weakness (20.0%), ataxia (20.0%) and vertigo (27.7%). Syringomyelia was present in 12 patients. A significant improvement of preoperative clinical symptoms and signs was observed in 28 patients (93.3%). Two children required adjunctive surgery. Neuroimaging revealed minor postoperative modifications in most cases regardless of tonsils location, while syringomyelia was reduced in size in 50% of the cases. Complication rate and length of hospital stay were significantly reduced compared with the literature data and our own experience using more invasive techniques. These data, compared with the literature, allow us to conclude that suboccipital craniectomy and Cl laminectomy (possibly integrated by dural delamination) is an effective and safe treatment for symptomatic children with Chiari I malformation and syringomyelia.

Endoscopic third ventriculostomy in the management of Chiari I malformation and syringomyelia associated with hydrocephalus

BACKGROUND

Chiari malformation with syringomyelia is conventionally managed with foramen magnum decompression and duroplasty. In presence of hydrocephalus, a ventriculoperitoneal shunt insertion has been the initial preferred mode of treatment.

METHODS

Two patients of Chiari I malformation with syringomyelia who had associated hydrocephalus were initially treated with endoscopic third ventriculostomy (ETV).

RESULTS

At follow up, both the patients symptomatically improved. Repeat MRI studies revealed collapse of the syrinx cavity and reduction of the Chiari malformation.

CONCLUSIONS

Chiari malformation and syrinx associated with hydrocephalus may be effectively managed with endoscopic third ventriculostomy.

Origin of macrophages in a kaolin-induced model of rat syringomyelia: a study using radiation bone marrow chimeras

STUDY DESIGN

Animal experimental study.

OBJECTIVE

To study the origin of macrophages in a rat model of syringomyelia.

SUMMARY OF BACKGROUND DATA

Syringomyelia is a clinically important condition in which a cystic cavity forms within the spinal cord. This leads to significant delayed neurologic deterioration, which may be manifested as weakness, numbness, or pain. The pathophysiology and mechanism of syrinx formation remain unclear. Human autopsy findings have demonstrated a prominent accumulation of macrophages in relation to the syrinx. Similar observations have also been made in a previously established rat model of syringomyelia. Little is known about the origin and precise functions of these cells.

METHODS

Syrinx formation was induced by intraparenchymal injections of kaolin within the cervical spinal cords of 30 DA rat (RT7.1) radiation bone marrow chimeras reconstituted with bone marrow from RT7.2 congeneic donors. The distribution of macrophages was evaluated at survival times of 3 days, 1 week, and 4 weeks. Immunostaining of fresh-frozen spinal cord tissue was performed using specific antibodies against rat macrophage ED1 antigen and RT7.2 allele of CD45. This allowed donor-derived hematogenous (ED1+, RT7.2+) macrophages to be distinguished from native cells (ED1+, RT7.2-).

RESULTS

Central canal dilatation was seen from 1 week. This was associated with extensive accumulation of ED1+ macrophages within the spinal cord parenchyma. A large influx of bone marrow-derived (ED1+, RT7.2+) macrophages was observed. However, a considerable proportion of resident microglia (RT7.2-) also upregulated ED1. These activated microglia demonstrated distinct morphologic features.

CONCLUSIONS

Large numbers of macrophages were recruited from the bone marrow in kaolin-induced rat syringomyelia. However, a significant number of resident microglia upregulated their ED1 activity and appear to provide a substantial source of macrophages.

Effects of surgery on the sensory deficits of syringomyelia and predictors of outcome: a long term prospective study

OBJECTIVE

To quantify the effects of surgery on the thermal deficits of syringomyelia and assess the predictors for such effects.

METHODS

The subjects were 16 consecutive patients (12 men, 4 women; mean (SD) duration of sensory symptoms, 5.1 (4.5) years) presenting with the typical symptoms of syringomyelia related to Chiari I malformation or trauma, and requiring surgical treatment. They were evaluated before surgery, then at six months and two years. Sensory evaluation included determination of the extent of thermal deficits and quantitative assessment of thermal, mechanical, vibration detection, and pain thresholds. Neuropathic pain intensity was evaluated on visual analogue scales. Magnetic resonance imaging was done before and after surgery to measure syrinx dimensions.

RESULTS

The magnitude and extent of thermal deficits improved in a subgroup of patients and this was best predicted by the duration of sensory symptoms: patients operated on less than two years after the onset of their symptoms tended to improve, while those operated on later were stabilised or deteriorated slightly. The effect of surgery on thermal deficits was correlated with the duration of sensory symptoms. Surgery also affected vibration deficits in patients with the Chiari malformation, neuropathic pain on effort, and syrinx dimensions.

CONCLUSIONS

The duration of sensory deficits is the best predictive factor of the efficacy of surgery for the thermal symptoms of syringomyelia. Early surgery is required if these deficits are to be minimised.

The pathogenesis of syringomyelia associated with lesions at the foramen magnum: a critical review of existing theories and proposal of a new hypothesis

Syringomyelia is frequently accompanied by an extramedullary lesion at the foramen magnum, particularly a Chiari I malformation. Although syringomyelia associated with foramen magnum obstruction has characteristic clinical, radiological, and neuropathological features, its pathogenesis remains unclear. Currently prevalent hydrodynamical theories assert that obstruction of the subarachnoid space at the foramen magnum interferes with flow of cerebrospinal fluid (CSF) between the spinal and the intracranial subarachnoid compartments. As a result, spinal CSF is driven into the spinal cord through the perivascular spaces to form a syrinx. These theories are implausible biophysically because none postulates a pump adequate to drive fluid through these spaces. None of the theories can explain why syrinx pressure is higher than CSF pressure; why extensive gliosis, edema, and vascular wall thickening regularly occur; and why the composition of syrinx fluid is not identical with that of CSF. A new theory of pathogenesis is proposed to address these difficulties. In the presence of subarachnoid obstruction at the foramen magnum, a variety of activities, such as assuming the erect posture, coughing or straining, and pulsatile fluctuations of CSF pressure during the cardiac cycle, produce transiently higher CSF pressure above the block than below it. There are corresponding changes in transmural venous and capillary pressure favoring dilation of vessels below the block and collapse of vessels above the block. The spatially uneven change of vessel caliber produces mechanical stress on the spinal cord, particularly caudal to the block. The mechanical stress, coupled with venous and capillary dilation, partially disrupt the blood-spinal cord barrier, allowing ultrafiltration of crystalloids and accumulation of a protein-poor fluid. The proposed theory is consistent with the neuropathological findings in syringomyelia and with the pressure and composition of syrinx fluid. It also accounts for the prolonged course of syringomyelia and its aggravation by cough, strain, and assumption of an erect posture. It contributes to understanding the low incidence and the morphology of syringobulbia. It explains the poorly understood presentation of foramen magnum meningiomas with symptoms of a mid- to low-cervical myelopathy. The theory also affords an understanding of the late recurrence of symptoms in children with hydromyelia who are treated with a ventricular shunt.

Surgical experience of syringomyelia with reference to the findings of magnetic resonance imaging

We present our surgical experience of 20 patients with syringomyelia, who were divided into two groups based on the findings of magnetic resonance (MR) imaging: a "non-visible cisterna magna" group, in which MR imaging did not reveal cerebrospinal fluid (CSF) in the cisterna magna, and a "visible cisterna magna" group. Patients with non-visible cisterna magna were associated with Chiari malformation (14 patients) or tight cisterna magna (4 patients) and underwent craniocervical decompression. Intradural exploration was performed when CSF movement in the cisterna magna or CSF outflow from the fourth ventricle appeared to be insufficient. It is important to confirm CSF outflow from the foramen of Magendie. Patients with visible cisterna magna were associated with tuberculous meningitis (2 patients) and underwent shunting procedures. Postoperatively, improvement in symptoms and a reduction in syrinx size were demonstrated in all patients except one. Two patients experienced recurrence of symptoms and syrinx dilatation.

Spontaneous resolution of syringomyelia: report of two cases and review of the literature

OBJECTIVE AND IMPORTANCE

The natural history of syringomyelia is highly unpredictable, and some patients experience improvement or stabilization without surgery. However, the mechanisms of the formation and spontaneous resolution of syringomyelia remain controversial. This report concerns two patients with syringomyelia who demonstrated spontaneous reductions in syrinx size, accompanied by symptomatic improvement.

CLINICAL PRESENTATION

One patient was a 10-year-old girl with syringomyelia associated with a tight cisterna magna and basilar impression, who demonstrated a spontaneous decrease in syrinx size, accompanied by symptomatic improvement, in 22 months. The other patient was a 39-year-old man with syringomyelia associated with a Chiari I malformation, who demonstrated a spontaneous reduction in syrinx size and neurological improvement, accompanied by elevation of the cerebellar tonsils, 6 months after diagnosis.

INTERVENTION

The patients were monitored.

CONCLUSION

The mechanisms of spontaneous resolution of syringomyelia, as well as the factors leading to the cerebrospinal fluid flow disturbances that cause syringomyelia, may vary. Resolution of foramen magnum lesion-related syringomyelia may be the result of spontaneous correction of the abnormal cerebrospinal fluid flow, as observed in our cases, or of cavity fluid drainage into the spinal arachnoid space because of spinal cord fissuring.

Surgical experience in 130 pediatric patients with Chiari I malformations

OBJECT

The aim of this study was to present the long-term findings of a surgical series of pediatric patients with Chiari I malformations.

METHODS

One hundred thirty symptomatic pediatric patients with Chiari I malformations underwent posterior fossa decompression. The age in this group of patients ranged from 2 months to 20 years (mean 11 years). The length of the hospital stay extended from 2 to 7 days (mean 2.7 days), and follow up was from 3 months to 15 years (mean 4.2 years). Patients most often presented with headache/neck pain (38%) and scoliosis (18%). Examples of associated diagnoses included neurofibromatosis Type 1 (5.5%), hydrocephalus (11%), idiopathic growth hormone deficiency (5.5%), and Klippel-Feil anomaly (5%). Syringes were present in 58% of patients. Seventeen percent of patients had caudal displacement of the brainstem and fourth ventricle. Postoperative relief of preoperative pathologies was experienced in 83% of patients. Of the most common presenting symptoms--headache/neck pain and scoliosis--12 and 17%, respectively, were not alleviated postoperatively. Complications occurred in 2.3% of this group and included the development of acute hydrocephalus postoperatively and severe life-threatening signs of brainstem compression that necessitated a transoral odontoidectomy. Nine patients have had to undergo repeated operations for continued symptoms or persistent large syringes. During surgery 10 patients (7.7%) were found to have arachnoid veils occluding the fourth ventricular outlet, and nine of these had syringomyelia. In our experience almost all syringes will stabilize or improve with posterior fossa decompression and duraplasty.

CONCLUSIONS

The authors believe this to be the largest reported series of pediatric patients who have undergone posterior fossa decompression for Chiari I malformations.

Post-traumatic syringomyelia: a review

More than a quarter of spinal cord injured patients develop syringes and many of these patients suffer progressive neurological deficits as a result of cyst enlargement. The mechanism of initial cyst formation and progressive enlargement are unknown, although arachnoiditis and persisting cord compression with disturbance of cerebrospinal fluid flow appear to be important aetiological factors. Current treatment options include correction of bony deformity, decompression of the spinal cord, division of adhesions, and shunting. Long-term improvement occurs in fewer than half of patients treated. Imaging evidence of a reduction in syrinx size following treatment does not guarantee symptomatic resolution or even prevention of further neurological loss. A better understanding of the causal mechanisms of syringomyelia is required to develop more effective therapy.

Improvement in brainstem auditory evoked potentials after suboccipital decompression in patients with chiari I malformations

OBJECT

The optimal treatment for patients with symptoms related to Chiari I malformation remains controversial. Although a suboccipital decompression with duraplasty is most commonly performed, there may be a subset of patients who improve in response to bone decompression alone. In an initial attempt to identify such patients, we performed a continuous study of intraoperative brainstem auditory evoked potentials (BAEPs) in patients undergoing a standard decompression with duraplasty and compared conduction times at three different time points: 1) baseline while the patient is supine (before positioning); 2) immediately after opening of the bone and release of the atlantooccipital membrane (that is, the dural band); and 3) after opening of the dura mater.

METHODS

Eleven children and young adults (mean age 9.8 years) with symptoms related to Chiari I malformation underwent suboccipital decompression and duraplasty with intraoperative monitoring of BAEPs and somatosensory evoked potentials (SSEPs). Six patients (55%) had associated syringomyelia. At baseline, the I to V interpeak latency (IPL) for both sides (total 21 BAEPs) was 4.19 +/- 0.22 msec (mean +/- standard deviation). After complete bone decompression and before the dura mater was opened, the I to V IPL decreased to 4.03 +/- 0.25 msec (p = 0.0005). When the dura was opened, however, no further decrease in the I to V IPL was detected (4.03 +/- 0.25 msec; p = 0.6). The SSEPs remained stable throughout the procedure.

CONCLUSIONS

In children and young adults undergoing suboccipital decompression with duraplasty for Chiari I malformation, the vast majority of improvement in conduction through the brainstem occurs after bone decompressionand division of the atlantooccipital membrane, rather than after opening of the dura. Additional studies are needed to establish whether the improvement seen with BAEP monitoring during bone decompression will predict long-term clinical improvement in these patients.

Decompression of the spinal subarachnoid space as a solution for syringomyelia without Chiari malformation

STUDY DESIGN

Review and analysis of seven cases of syringomyelia treated surgically.

OBJECTIVE

To demonstrate the beneficial role of decompressive surgery for the altered cerebrospinal fluid (CSF) flow dynamics in syringomyelia not associated with Chiari I malformation. A comparison between the pre- and post-operative syrinx size and CSF flow in the subarachnoid space was made using cine-mode magnetic resonance imaging (cine-MRI) and then correlated with clinical improvement.

SETTING

University Hospital, Seoul, Korea.

METHODS

Conventional spinal MRI and cine-MRI were performed in the region of CSF flow obstruction preoperatively in seven patients with syringomyelia not associated with Chiari I malformation. The group consisted of one case of syrinx with post-traumatic compression fracture, one case of post-traumatic arachnoiditis, two cases of holocord syrinx associated with hydrocephalus without Chiari malformation, one case of syrinx with post-traumatic pseudomeningeal cyst, one case of post-laminectomy kyphosis-associated syringomyelia and one case of post-tuberculous arachnoiditis syringomyelia. Based on the preoperative cine-MRI, the types of surgery appropriate to correct the CSF flow obstruction were chosen: decompressive laminectomy-adhesiolysis and augmentation duraplasty in arachnoiditis cases, ventriculoperitoneal shunt for hydrocephalus, cyst extirpation in pseudomeningeal cyst and both anterior and posterior decompression-fusion in the case of post-laminectomy kyphosis. A syrinx-draining shunt operation was performed in three cases; where the syringomyelia was associated with post-traumatic compression fracture refractory to a previous decompression, where hydrocephalus was present in which the decompression by ventriculoperitoneal shunt was insufficient and where post-traumatic arachnoiditis was present in which the decompression was impossible due to diffuse adhesion. Change in syrinx size was evaluated with post-operative MRI in all seven cases and restoration of flow dynamics was evaluated with cine-MRI in three of the cases, two patients with clinical improvement and one patient with no change of clinical status, respectively.

RESULTS

Four out of seven patients showed symptomatic improvement after each decompressive operation. In the remaining three cases, reconstruction of the spinal subarachnoid space was not possible due to diffuse adhesion or was not the main problem as in the patient with syrinx associated with hydrocephalus who had to undergo a shunt operation. One of these three patients showed clinical improvement after undergoing syringosubarachnoid shunt. A decrease of syrinx size was observed in only two out of the five patients who showed clinical improvement after treatment. Of these five patients, two patients underwent post-operative cine-MRI and the restoration of normal CSF flow dynamics was noted in both patients. Of the remaining two patients, one underwent post-operative cine-MRI and there was no change in the CSF flow dynamics evident.

CONCLUSION

These results suggest that the restoration of CSF flow dynamics between the syrinx and the subarachnoid space by decompressive operation is more effective than simple drainage of the syrinx cavity itself in the treatment of syringomyelia without Chiari malformation.

Syringomyelia without hindbrain herniation: tight cisterna magna. Report of four cases and a review of the literature

Idiopathic syringomyelia, which is not associated with any definite pathogenic lesions, has been treated mainly by shunting of the syrinx and rarely by craniocervical decompression. The authors report four cases of syringomyelia thought to be idiopathic syringomyelia but treated by craniocervical decompression with favorable results. Syringomyelia was present without hindbrain herniation. In such cases, the subarachnoid space anterior to the brainstem at the level of the foramen magnum is usually open but the cisterna magna is impacted by the tonsils, a condition the authors term "tight cisterna magna." All patients underwent foramen magnum decompression and C-1 laminectomy, and the outer layer of the dura was peeled off. Further intradural exploration was performed when outflow of cerebrospinal fluid (CSF) from the fourth ventricle was deemed to be insufficient. Postoperatively, improvement in symptoms and a reduction in syrinx size were demonstrated in three patients, and a reduction in ventricle size was shown in two. Syringomyelia associated with tight cisterna magna should not be classified as idiopathic syringomyelia; rather, it belongs to the category of organic syringomyelia such as Chiari malformation. A possible pathogenesis of cavitation is obstruction of the CSF outflow from the foramen of Magendie, and the cavity may be a communicating dilation of the central canal. Ventricular dilation may depend on the extent to which CSF drainage is impaired from the foramina of Luschka. These cavities may respond to craniocervical decompression if it results in sufficient CSF outflow from the foramen of Magendie, even in cases with concomitant hydrocephalus.

Dandy-Walker complex and syringomyelia in an adult: case report and discussion

OBJECTIVE AND IMPORTANCE

Syringomyelia in association with the Dandy-Walker complex is rare and only 17 cases have been reported, mostly as autopsy findings or incidental reports in series for other conditions. We present a further case report and discuss the possible pathogenetic mechanisms of syrinx formation in the presence of the Dandy-Walker complex. We emphasize the role of foramen magnum obstruction and alteration in cerebrospinal fluid flow dynamics in syrinx formation. The therapeutic importance of disimpaction of the foramen magnum is stressed.

CLINICAL PRESENTATION

A 39-year-old man presented with headache. As a child, he had had cystoperitoneal and ventriculoperitoneal shunts inserted for hydrocephalus in association with the Dandy-Walker complex. On examination, the patient had limited upgaze but was otherwise normal. Magnetic resonance imaging revealed a large cervicothoracic syrinx and a Dandy-Walker cyst obstructing the foramen magnum.

INTERVENTION

The cystoperitoneal shunt was revised. The patient's headaches resolved, and follow-up imaging demonstrated resolution of the syrinx and disimpaction of the foramen magnum.

CONCLUSION

Disimpaction of the foramen magnum can resolve syringomyelia in patients with the Dandy-Walker complex. This can be achieved by a shunt procedure or by formal foramen magnum decompression. The rarity of the association between the Dandy-Walker complex and syringomyelia prevents firm conclusions from being made regarding the best management strategy for this condition.

Otologic manifestations of Chiari I malformation

OBJECTIVE

To assess the prevalence of otologic symptoms in patients undergoing surgical decompression for symptomatic Chiari I malformation.

STUDY DESIGN

Cross-sectional, prospective, nonrandomized.

SETTING

Urban tertiary referral center.

PATIENTS

Patients with Chiari I malformation before surgical intervention.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE

Results of completed questionnaire.

RESULTS

Sixteen consecutive patients with Chiari I malformation completed the self-administered questionnaire. Eighty-one percent of patients reported episodic aural fullness, 81% reported tinnitus, 69% reported vertigo, and 56% reported fluctuating hearing loss. Headaches were reported as frequently as aural fullness and tinnitus.

CONCLUSIONS

Most patients with Chiari I malformation have symptoms that mimic primary otologic pathologic changes. The existence of common pathophysiologic mechanisms is proposed.

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.