Surgical indication and results of foramen magnum decompression versus syringosubarachnoid shunting for syringomyelia associated with Chiari I malformation

Prediction of Curve Progression After Posterior Fossa Decompression in Pediatric Patients With Scoliosis Secondary to Chiari Malformation

OBJECTIVE

In this retrospective radiographic and clinical study, we analyzed the evolution of scoliosis after posterior fossa decompression (PFD) to determine the predictors of curve progression after PFD in patients with scoliosis secondary to Chiari malformation type I (CM-I) and syringomyelia (SM). Institutional Review Board approval was obtained to conduct the study. Previous studies have shown that PFD can improve the associated scoliosis in some patients with CM-I, and certain clinical factors can predict curve progression after PFD. However, the results were often contradictory.

METHODS

In our study, 54 patients with CM-I who underwent a standard PFD were divided into 2 groups according to the evolution of scoliosis after PFD. One group consisted of "progressors" with curve progression of more than 5° from before PFD to the final follow-up; the other group consisted of "nonprogressors" with curve stabilization or improvement. Clinical and radiographic data were compared between progressors and nonprogressors.

RESULTS

Twenty-five of the patients received brace treatment, and 11 patients underwent spinal fusion. Nineteen patients were identified as progressors, and 35 were nonprogressors. Age, curve type, curve magnitude, and bracing treatment were independent predictors for curve progression after PFD. Both an age ≥ 10.5 years and a Cobb angle ≥ 44.5° were strongly predictive factors for curve progression. Regarding those patients with an indication for bracing, a significant difference (p=.009) was noted in terms of the evolution of scoliosis between patients with and without bracing treatment.

CONCLUSION

PFD had an effect on the regression of scoliosis in 64.8% of the CM-I patients. An age ≥ 10.5 years, a Cobb angle ≥ 44.5°, and double curves were factors that could predict the progression of scoliosis in these patients. Additionally, we advocate that bracing treatment may be effective in some skeletally immature patients.

Surgical management of patients with Chiari I malformation

Chiari malformations (CMs) constitute a variety of four mainly syndromes (I, II, III, and IV), which describe the protrusion of brain tissue into the spinal canal through the foramen magnum. These malformations frequently occur in combination with other pathological entities such as myelomeningocele, hydrocephalus, and/or hydrosyringomyelia. The recent improvement of imaging techniques has increased not only the rate of CM diagnosis but also the necessity for its early treatment. Several different surgical techniques have been employed in the treatment of patients with symptomatic CM-I. In our current study, a systematic and critical review of the pertinent literature was made for identifying the most commonly employed surgical procedures in the management of these patients. Emphasis was given in outlining the advantages and disadvantages of each surgical approach. Moreover, an attempt was made for defining those parameters that may be prognostic factors for their surgical outcome. There is a consensus that surgical treatment is reserved only for symptomatic patients with CM-I. It has also been postulated that early surgically intervention is usually associated with better outcome. Despite the large number of previously published clinical series, further clinical research with large-scale studies is necessary for defining surgical treatment guidelines in these patients.

Syringosubarachnoid shunt as a management for syringohydromyelia in dogs

OBJECTIVE

To evaluate retrospectively the efficacy of syringosubarachnoid shunt for the management of syringohydromyelia/syringomyelia.

METHODS

Eleven dogs diagnosed with syringohydromyelia/syringomyelia by magnetic resonance imaging associated with Chiari-like malformation underwent placement of a syringosubarachnoid shunt at the cervical (nine dogs) or lumbar (two dogs) spinal cord. In one dog, a suboccipital decompression (foramen magnum decompression) was performed 4 months before inserting a syringosubarachnoid shunt. All dogs were evaluated neurologically a few hours after surgery, 2 weeks and 6 months postoperatively. Retrospectively, cases were assigned a preoperative and postoperative pain score.

RESULTS

There were no intra- or peri-operative complications. One dog (9%) was euthanased 5 weeks after surgery. Progressive neurological improvement was observed in nine dogs (81·8%) 2 weeks and 6 months postoperatively. No clinical improvement was seen in another dog (9%). One dog (9%) had replacement of the syringosubarachnoid shunt. Seven dogs (63·6%) were still alive 1 to 4 years (mean, 2·6 years) after surgery.

CLINICAL SIGNIFICANCE

Placement of a syringosubarachnoid shunt in the presence of a sufficiently large syrinx appears to be beneficial in dogs with Chiari-like malformation and associated syringohydromyelia/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.

Chiari type I malformation in children

The diagnosis of Chiari type I malformation (CIM) is more and more frequent in clinical practice due to the wide diffusion of magnetic resonance imaging. In many cases, such a diagnosis is made incidentally in asymptomatic patients, as including children investigated for different reasons such as mental development delay or sequelae of brain injury. The large number of affected patients, the presence of asymptomatic subjects, the uncertainties surrounding the pathogenesis of the malformation, and the different options for its surgical treatment make the management of CIM particularly controversial.This paper reports on the state of the art and the recent achievements about CIM aiming at providing further information especially on the pathogenesis, the natural history, and the management of the malformation, which are the most controversial aspects. A historial review introduces and explains the current classification. Furthermore, the main clinical, radiological, and neurophysiological findings of CIM are described to complete the picture of this heterogeneous and complex disease.

Pathophysiology of persistent syringomyelia after decompressive craniocervical surgery. Clinical article

OBJECT

Craniocervical decompression for Chiari malformation Type I (CM-I) and syringomyelia has been reported to fail in 10%-40% of patients. The present prospective clinical study was designed to test the hypothesis that in cases in which syringomyelia persists after surgery, craniocervical decompression relieves neither the physiological block at the foramen magnum nor the mechanism of syringomyelia progression.

METHODS

The authors prospectively evaluated and treated 16 patients with CM-I who had persistent syringomyelia despite previous craniocervical decompression. Testing before surgery included the following: 1) clinical examination; 2) evaluation of the anatomy using T1-weighted MR imaging; 3) assessment of the syrinx and CSF velocity and flow using cine phase-contrast MR imaging; and 4) appraisal of the lumbar and cervical subarachnoid pressures at rest, during a Valsalva maneuver, during jugular compression, and following the removal of CSF (CSF compliance measurement). During surgery, ultrasonography was performed to observe the motion of the cerebellar tonsils and syrinx walls; pressure measurements were obtained from the intracranial and lumbar intrathecal spaces. The surgical procedure involved enlarging the previous craniectomy and performing an expansile duraplasty with autologous pericranium. Three to 6 months after surgery, clinical examination, MR imaging, and CSF pressure recordings were repeated. Clinical examination and MR imaging studies were then repeated annually.

RESULTS

Before reexploration, patients had a decreased size of the CSF pathways and a partial blockage in CSF transmission at the foramen magnum. Cervical subarachnoid pressure and pulse pressure were abnormally elevated. During surgery, ultrasonographic imaging demonstrated active pulsation of the cerebellar tonsils, with the tonsils descending during cardiac systole and concomitant narrowing of the upper pole of the syrinx. Three months after reoperation, patency of the CSF pathways was restored and pressure transmission was improved. The flow of syrinx fluid and the diameter of the syrinx decreased after surgery in 15 of 16 patients.

CONCLUSIONS

Persistent blockage of the CSF pathways at the foramen magnum resulted in increased pulsation of the cerebellar tonsils, which acted on a partially enclosed cervical subarachnoid space to create elevated cervical CSF pressure waves, which in turn affected the external surface of the spinal cord to force CSF into the spinal cord through the Virchow-Robin spaces and to propel the syrinx fluid caudally, leading to syrinx progression. A surgical procedure that reestablished the CSF pathways at the foramen magnum reversed this pathophysiological mechanism and resolved syringomyelia. Elucidating the pathophysiology of persistent syringomyelia has implications for its primary and secondary treatment.

Syringomyelia associated with Chiari I malformation treated with foramen magnum decompression and duraplasty using a polyglycolic acid patch and fibrin glue: a case report

A 31-year-old woman presented with worsening numbness and pain in the arms and chest. Neurological findings at admission were decreased pain sensation and temperature sensation in the arms and chest. Magnetic resonance demonstrated a large cervical syrinx from the level of C4 to Th4 associated with Chiari I malformation. Occipital craniectomy and C1 laminectomy were performed for foramen magnum decompression. Intraoperative ultrasonography, performed after removal of the outer membrane of the dura mater at the level of the foramen magnum, revealed insufficient decompression. Therefore, the dura mater was completely opened and duraplasty was performed with a polyglycolic acid patch and fibrin glue. Sufficient decompression was thus achieved. The neurological symptoms and signs improved within the first postoperative month, and magnetic resonance showed a decrease in the size of the syrinx and no cerebrospinal fluid leakage. In patients undergoing foramen magnum decompression with duraplasty, the use of a polyglycolic acid patch and fibrin glue renders suturing unnecessary and avoids the common complications associated with suture duraplasty.

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.

Surgical outcomes of foramen magnum decompression for syringomyelia associated with Chiari I malformation: relation between the location of the syrinx and body pain

BACKGROUND

There have been few reports about the relation between the morphology of syrinxes and body pain in syringomyelia associated with Chiari I malformation. To investigate this phenomenon, the relation between the location of the syrinx and body pain before and after foramen magnum decompression (FMD) were evaluated.

METHODS

The subjects were 20 patients with Chiari I malformation associated with syringomyelia who underwent FMD. The morphology of the syrinxes was classified into three types - enlarged type, which was a distended syrinx at the central spinal cord; deviated type, which was a deviated syrinx posterolaterally within the spinal cord; central type, which was a small syrinx at the central canal of the spinal cord - based on axial magnetic resonance imaging (MRI). Preoperative and postoperative clinical symptoms and the body pain were evaluated by the Japanese Orthopaedic Association (JOA) score and a visual analogue scale (VAS) prospectively.

RESULTS

Preoperative and postoperative JOA scores showed no statistically significant differences between the three syrinx types. Intensity of body pain evaluated by the VAS showed that patients with a deviated-type syrinx on pre- and postoperative MRI tended to be associated with more intense pain than the other two types.

CONCLUSIONS

It was indicated that pain before and after surgery is more intense when the syrinx is deviated toward the spinal dorsal horn as seen on MRI.

Syringopleural shunt as a rescue procedure in patients with syringomyelia refractory to restoration of cerebrospinal fluid flow

OBJECTIVE

Syringomyelia should be treated by reconstruction of the subarachnoid space and restoration of cerebrospinal fluid homeostasis. Direct intervention on the syrinx is a difficult choice and should be considered a rescue procedure. Data in the literature examining the various options are scanty, with generally unsatisfying results. We report our experience with shunting of the syrinx into the pleural space.

METHODS

Twenty patients with syringomyelia refractory to cerebrospinal fluid flow restoration underwent a procedure for placement of a syringopleural shunt between 1998 and 2008. Modified Japanese Orthopaedic Association Scale scores and magnetic resonance imaging were available for each patient preoperatively and at the latest follow-up evaluation. A 2-tailed Wilcoxon signed-rank test was used for statistical analysis. Complications related to the operative procedure and to hardware failure were noted.

RESULTS

Nineteen patients were available for follow-up with a mean duration of 37.5 (standard deviation, 31.1) months. The condition of 1 patient deteriorated, 2 remained stable, and the remainder improved. The overall mean improvement on the Modified Japanese Orthopaedic Association Scale was 19.5% (95% confidence interval, 8.5-30.5). The median improvement was 4 points on the 17-point scale. Results were statistically significant (P < 0.001). Follow-up magnetic resonance imaging showed syrinx collapse in 17 cases and marked shrinkage in 2 cases. Except for 1 case of meningitis followed by fatal pulmonary embolism, no significant complications were noted.

CONCLUSION

A syringopleural shunt should, in our view, be the syrinx diversion procedure of choice. More series of institutional experiences with a homogeneous approach would be helpful to verify this recommendation.

Delamination technique together with longitudinal incisions for treatment of Chiari I/syringomyelia complex: a prospective clinical study

Background

Treatment modalities in Chiari malformation type 1(CMI) accompanied by syringomyelia have not yet been standardized. Pathologies such as a small posterior fossa and thickened dura mater have been discussed previously. Various techniques have been explored to enlarge the foramen magnum and to expand the dura. The aim of this clinical study was to explore a new technique of excision of the external dura accompanied by widening the cisterna magna and making longitudinal incisions in the internal dura, without disturbing the arachnoid.

Methods

Ten patients with CMI and syringomyelia, operated between 2004 and 2006, formed this prospective series. All cases underwent foramen magnum decompression of 3 × 3 cm area with C1–C2 (partial) laminectomy, resection of foramen magnum fibrous band, excision of external dura, delamination and widening of internal dura with longitudinal incisions.

Results

Patients were aged between 25 and 58 years and occipital headache was the most common complaint. The mean duration of preoperative symptoms was 4 years and the follow-up time was 25 months. Clinical progression was halted for all patients; eight patients completely recovered and two reported no change. In one patient, there was a transient cerebrospinal fluid (CSF) fistula that was treated with tissue adhesive. While syringomyelia persisted radiologically with radiological stability in five patients; for three patients the syringomyelic cavity decreased in size, and for the remaining two it regressed completely.

Conclusion

Removal of the fibrous band and the outer dural layer, at level of foramen magnum, together with the incision of inner dural layer appears to be good technique in adult CMI patients. The advantages are short operation time, no need for duraplasty, sufficient posterior fossa decompression, absence of CSF fistulas as a result of extra arachnoidal surgery, and short duration of hospitalization. Hence this surgical technique has advantages compared to other techniques.

Detection of residual disc hernia material and confirmation of nerve root decompression at lumbar disc herniation surgery by intraoperative ultrasound

The aim of lumbar disc herniation surgery is the removal of herniated disc material (HDM) and complete decompression of the nerve root. As some patients present with residual HDM, we examined the ability of intraoperative ultrasound (IOUS) to detect this material. Between February 2006 and June 2007, we used IOUS in 30 patients undergoing surgery for lumbar disc herniation. They were 17 men and 13 women; their ages ranged from 22 to 63 y (mean 44.0 y). The level surgically addressed was L3/4 in 1, L4/5 in 14 and L5/S1 in 15 patients; they were operated in the prone position. After placing a 3-4 cm midline skin incision, partial hemi-semilaminotomy was performed. HDM was removed through a bone window; a surgical microscope was used during the operation. After removal was judged as adequate, IOUS was performed; 17 patients also underwent IOUS before removal of the herniated disc. For the acquisition of IOUS images, we used LOGIQ 9 and 8c microconvex probes (GE Healthcare, Wauwatosa, WI, USA). The normal anatomical structures were well visualized. HDM was iso- to hyperechoic compared with normal nerve tissue. In three of 17 patients, the dural sac and nerve root could not be distinguished from HDM before removal, although in all 30, the decompressed dural sac, intradural cauda equina and nerve root were well visualized. We posit that the echogenicity of nerve tissue was raised due to compression, rendering it similar to that of the herniated disc. In two patients, IOUS detected residual disc material; the surgical procedure was resumed and sufficient removal was accomplished. IOUS monitoring is safe, convenient and inexpensive. It is also highly useful for the detection of residual HDM and the confirmation of adequate nerve root decompression.

Long-term follow-up of Chiari-related syringomyelia in adults: analysis of 157 surgically treated cases

OBJECTIVE

To determine the long-term outcome of surgically treated Chiari-related syringomyelia.

METHODS

The medical charts of 157 consecutive surgically treated patients with Chiari-related syringomyelia were retrospectively analyzed. Factors predicting outcome, either clinical or radiological, are discussed, and our results are compared with those of other large series in the literature.

RESULTS

The study included 74 men and 83 women (age range, 16-75 years; mean age at surgery, 38.3 years). Pain and sensory disturbance were the most frequent initial symptoms. The average duration of preoperative symptoms was 8.2 years. The follow-up period ranged from 82 to 204 months (median, 88 months). At the end of the study, 99 patients (63.06%) had improved, 48 (30.58%) had stabilized, 9 (5.73%) had worsened, and 1 (0.63%) had died during the postoperative period. Factors predicting improvement or stabilization were young age at the time of surgery and clinical signs of paroxysmal intracranial hypertension. Factors associated with a poor outcome were older age at the time of surgery, arachnoiditis, and a clinical feature of long-tract impairment syndrome. The presence of arachnoiditis or of basilar invagination was associated with poor clinical presentation (P = 0.05 and 0.0001, respectively). The extent of the cyst on postoperative magnetic resonance imaging was a predictor of poor clinical outcome (P = 0.002).

CONCLUSION

Our results confirmed that surgery is an effective and safe treatment of Chiari-related syringomyelia, with a 90% chance of long-term stabilization or improvement on average. Surgery should be proposed as soon as possible in patients with clearly progressing clinical features.

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.

Suboccipital decompression for Chiari I malformation: outcome comparison of duraplasty with expanded polytetrafluoroethylene dural substitute versus pericranial autograft

OBJECTIVE

Treatment failure for Chiari decompression is frequently associated with scarring, intradural adhesions, and recurrent loss of hindbrain space. While autograft has been our standard for hindbrain duraplasty, we investigated whether introducing anti-adhesive synthetic GORE PRECLUDE MVP Dura Substitute (expanded polytetrafluoroethylene [ePTFE] graft) was associated with improved patient outcomes.

MATERIALS AND METHODS

We retrospectively reviewed records of patients undergoing first-time suboccipital decompression/duraplasty for Chiari-I malformation utilizing ePTFE graft or pericranial autograft. Magnetic resonance imaging (MRI) at last follow-up was assessed for: (1) recurrent loss of dorsal hindbrain cerebrospinal fluid (CSF) space/CSF flow(cine-MR) at duraplasty site, (2) pseudomeningocele, or (3) syringomyelia improvement. Symptom recurrence warranting revision surgery was compared between cohorts.

RESULTS

Sixty-seven patients (age 11 +/- 5 years) underwent duraplasty with pericranial autograft (n = 40) or ePTFE graft (n = 27). Perioperative morbidity did not differ between cohorts. No patients receiving ePTFE graft experienced incisional CSF leak, surgical site infection, or symptomatic pseudomeningocele. At median 8 months postoperatively, all (100%) patients with ePTFE graft maintained physiological CSF flow/decompressed hindbrain CSF space on cine-MRI versus 32 (79%) patients receiving pericranial autograft (p < 0.05). Radiographic syrinx improvement occurred in 80% of patients with ePTFE graft and 52% of patients with pericranial autograft (median time to improvement: 5 vs 12 months, respectively, p < 0.05). At median 16 months postoperatively, four (10%) patients with pericranial autograft required revision decompression versus 0 (0%) patients with ePTFE graft (p = 0.090).

CONCLUSION

Duraplasty utilizing ePTFE graft was associated with improved maintenance of hindbrain space, accelerated syringomyelia improvement, and a trend toward decreased treatment failure versus pericranial autograft. Future studies of long-term outcome are warranted to confirm observed effects. Synthetic ePTFE graft is a safe alternative for duraplasty in the setting of Chiari malformation.

Care of the adolescent with spina bifida

Myelodysplasia with attendant spinal dysraphic disorders can be and often is progressive. In addition to the neurologic deficit present since the prenatal period, hydrocephalus, Chiari malformations with hydromyelia, tethered cord syndrome, or combinations of one or all lead to changing functional ability and progressive deformities. With recent advances in neurologic monitoring and treatment, many of these deformities can be prevented from appearing or becoming destabilizing if the subtle signs are picked up and early intervention is provided. Advances in urologic surgery have also provided better control of continence in addition to reduced infections and renal destruction. This article reviews the monitoring and treatment considerations that have led to such a significant improvement in outcomes in patients who have myelodysplasia.

Comparison of posterior fossa decompression with and without duraplasty for the surgical treatment of Chiari malformation Type I in pediatric patients: a meta-analysis

OBJECT

Surgery for Chiari malformation Type I (CM-I) is one of the most common neurosurgical procedures performed in children, although there is clearly no consensus among practitioners about which surgical method is preferred. The objective of this meta-analysis was to compare the outcome of posterior fossa decompression with duraplasty (PFDD) and posterior fossa decompression without duraplasty (PFD) for the treatment of CM-I in children.

METHODS

The authors searched Medline-Ovid, The Cochrane Library, and the conference proceedings of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons (2000-2007) for studies meeting the following inclusion criteria: 1) surgical treatment of CM-I; 2) surgical techniques of PFD and PFDD being reported in a single cohort; and 3) patient age < 18 years.

RESULTS

Five retrospective and 2 prospective cohort studies involving a total of 582 patients met the criteria for inclusion in the meta-analysis. Of the 582 patients, 316 were treated with PFDD and 266 were treated with PFD alone. Patient age ranged from 6 months to 18 years. Patients undergoing PFDD had a significantly lower reoperation rate (2.1 vs 12.6%, risk ratio [RR] 0.23, 95% confidence interval [CI] 0.08-0.69) and a higher rate of cerebrospinal fluid-related complications (18.5 vs 1.8%, RR 7.64, 95% CI 2.53-23.09) than those undergoing PFD. No significant differences in either clinical improvement (78.6 vs 64.6%, RR 1.23, 95% CI 0.95-1.59) or syringomyelia decrease (87.0 vs 56.3%, RR 1.43, 95% CI 0.91-2.25) were noted between PFDD and PFD.

CONCLUSIONS

Posterior fossa decompression with duraplasty is associated with a lower risk of reoperation than PFD but a greater risk for cerebrospinal fluid-related complications. There was no significant difference between the 2 operative techniques with respect to clinical improvement or decrease in syringomyelia.

Intraoperative ultrasonography as a guide to patient selection for duraplasty after suboccipital decompression in children with Chiari malformation Type I

OBJECT

Indications for duraplasty in treatment of Chiari malformation Type I (CM-I) remain unclear. In the present study, the authors evaluate their surgical experience to determine whether intraoperative ultrasonography is effective in the selection of patients with CM-I who can be adequately treated with craniectomy alone without duraplasty.

METHODS

The authors reviewed the records of 256 children who underwent first-time hindbrain decompression for CM-I. Craniectomy alone (without duraplasty) was performed when intraoperative ultrasonography suggested adequate decompression of the subarachnoid spaces ventral and dorsal to the tonsils after suboccipital craniectomy alone. Duraplasty was performed if intraoperative ultrasonography demonstrated persistent dural compression of the tonsils following craniectomy. Symptom recurrence as a function of time was compared between cases of duraplasty versus suboccipital decompression alone stratified by extent of tonsillar herniation.

RESULTS

Duraplasty was performed in 140 patients (55%), and suboccipital decompression alone was performed in 116 patients (45%). Patients underwent follow-up for 29 +/- 15 months. Symptoms included headache in 192 patients (75%) and lower cranial nerve and brainstem dysfunction in 68 (27%). In 38 patients (15%) there was tonsillar herniation rostral to the C-1 lamina, in 195 (76%) it extended between the C-1 and C-2 lamina, and in 23 patients (9%) there was herniation caudal to the lower border of the C-2 lamina. In children with tonsillar herniation caudal to C-1, ultrasonography-guided suboccipital decompression alone was associated with a 2-fold increase in the risk of symptom recurrence compared with those who also underwent duraplasty (p = 0.01). In children with tonsillar herniation rostral to C-1, outcome was equivalent between suboccipital decompression alone and duraplasty (p = 0.41).

CONCLUSIONS

In the setting of moderate-to-severe tonsillar CM-I, intraoperative ultrasonography demonstrating decompression of the subarachnoid spaces ventral and dorsal to the tonsils may not effectively select patients in whom bone decompression alone is sufficient. Duraplasty may be warranted in cases of tonsillar herniation that extends below the C-1 lamina regardless of intraoperative ultrasonography findings. More objective cerebrospinal fluid flow or volumetric measures may be needed intraoperatively to guide duraplasty in patients with more pronounced tonsillar herniation.

Syringomyelia-associated scoliosis with and without the Chiari I malformation

Although there may be a hereditary component to true idiopathic scoliosis, the condition has no known cause and is not associated with dysraphism. However, scoliosis with an associated syrinx, with or without the Chiari I malformation, sometimes presents as an idiopathic-type curve. Physical examination findings and subtle clues on diagnostic imaging may help the orthopaedic surgeon diagnose scoliosis associated with syringomyelia. Examination findings include asymmetric reflexes and presentation at ages younger than those of patients who present with adolescent idiopathic curves (i.e., 10 to 14 years). Radiologic findings include kyphosis at the apex of the curve. Indications for surgical decompression include progressive neurologic deficits, weakness, pain, and progressive curves. Most orthopaedic surgeons agree that a syrinx should be evaluated neurosurgically before any planned spinal arthrodesis to decrease the risk of neurologic injury connected with surgical correction. The indications for arthrodesis in these patients compared with those with idiopathic curves are evolving.

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.

Cerebrospinal Fluid-Related Complications With Autologous Duraplasty and Arachnoid Sparing in Type I Chiari Malformation

Objective:

Although there is a current consensus that Type I Chiari malformations (CM-I) should be treated only in the setting of symptomatic disease, significant controversy surrounds the most appropriate surgical procedure. Recent enthusiasm for osseous decompression without duraplasty is supported by the purportedly lower morbidity of this approach. Precise rates of morbidity with duraplasty, however, have not been reported. This study is intended to assess the cerebrospinal fluid-related morbidity associated with a patient population treated uniformly with autologous duraplasty for symptomatic CM-I.

Methods:

A review of one surgeon's practice (MMS) from 1997 to 2007 identified patients treated for symptomatic CM-I with osseous decompression and autologous duraplasty. A retrospective chart review was then performed for these patients with an emphasis on cerebrospinal fluid-related complications.

Results:

Forty patients were treated for CM-I with decompression and autologous duraplasty. Twenty-four patients presented with a preoperative syrinx. The mean age was 13.3 years, and the median age was 12.9 years (range, 3.3–45.8 yr). The mean follow-up period was 11.4 months (range, 1–101 mo). There was no mortality associated with the procedure. Clinical response was observed in 91.8% of patients, with 70.2% experiencing complete symptomatic resolution and 21.6% experiencing partial improvement. Two patients (5.4%) had persistent symptomatic syringomyelia requiring syringosubarachnoid shunting. There was an overall morbidity rate of 2.5% due to one pseudomeningocele treated with a single percutaneous tap. There were no incidences of cerebrospinal fluid leak, meningitis, or postoperative hydrocephalus.

Conclusion:

The cerebrospinal fluid-related morbidity associated with autologous duraplasty for CM-I in a uniformly treated population is negligible. These results challenge the current rationale for a less aggressive surgical approach to CM-I.

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.

Cervical spinal motion before and after surgery in patients with Chiari malformation type I associated with syringomyelia

OBJECT

There have been few reports about the cervical spinal motion in patients with Chiari malformation Type I (CM-I) associated with syringomyelia. To investigate this phenomenon, the relationship between the preoperative cervical range of motion (ROM) and the stage of cerebellar tonsillar descent as well as the cervical ROM before and after foramen magnum decompression (FMD) were evaluated.

METHODS

Thirty patients who had CM-I associated with syringomyelia and who underwent FMD participated in the study. The ROM and lordosis angle of the cervical spine were measured on x-ray films. In addition, the relationship between preoperative degree of cerebellar tonsillar descent and the ROM between the levels of the occiput (Oc) and C2 was investigated.

RESULTS

The mean flexion-extension ROM at Oc-C2 was 15.5 degrees before and 14.1 degrees after surgery, and the mean flexion-extension ROM of C2-7 was 55.1 degrees before and 52.8 degrees after surgery. The mean pre- and postoperative lordosis angles at C2-7 were 16.8 and 19.1 degrees, respectively. There was no significant difference between the values measured before and after surgery. There was no correlation between the degree of cerebellar tonsillar descent and the ROM at Oc-C2. CONCLUSIONS. Foramen magnum decompression is an excellent surgical technique that has no effect on the postoperative cervical ROM and cervical alignment.

The pediatric Chiari I malformation: a review

BACKGROUND

Both the diagnosis and treatment regimens for the Chiari I malformation (CIM) are varied and controversial. The present paper analyzes the literature regarding this form of hindbrain herniation in regard to definition, anatomy, pathobiology, symptoms, findings, treatment, and outcomes.

DISCUSSIONS

Appropriate literature germane to the CIM is reviewed and discussed. There is variation in the reported anatomy, outcome, and treatment for children with CIM. Based on the literature, most patients have preoperative symptoms or findings (e.g., syringomyelia) improve no matter what surgical technique is utilized. However, standardized treatment paradigms based on randomized controlled studies are still necessary to elucidate the optimal selection and treatment criteria.

Extra-arachnoidal cranio-cervical decompression for syringomyelia associated with Chiari I malformation in adults: technique assessment

BACKGROUND

The osteo-dural decompression of the cerebellar tonsils at the cranio-cervical junction is generally considered the most effective treatment for syringomyelia-Chiari I complex. However much controversy concerning a great number of surgical adjuvants to the standard bony decompression is still present. In this work an extra-arachnoidal cranio-cervical decompression (CCD) without duroplasty is described and the surgical results are reported.

METHOD

Between 2000 and 2005, 24 adult patients underwent surgery for symptomatic syringomyelia-Chiari I complex not associated with hydrocephalus. In all cases, the surgical procedure consisted of a limited suboccipital craniectomy and laminectomy of C1 (when necessary C2 as well) followed by dural opening leaving the arachnoid membrane intact. The dura mater is left open and stitched laterally to the muscles.

FINDINGS

With a mean clinical long term follow-up of 44 months (range, 12-78 mo), neurological disturbances improved in 21 of 24 patients (87.5%) as result of extra-arachnoidal CCD. The postoperative complications occurred when the arachnoid was accidentally violated (4 cases, 16.6%). The complications included aseptic meningitis (one patient), nucal pseudomeningocele (two patients) and postoperative hydrocephalus requiring a ventriculoperitoneal shunt (one patient). Finally, one patient received an additional C2 laminectomy in order to obtain symptoms improvement and syrinx shrinkage. Postoperative MRI studies demonstrated that the syrinx decreased in size or collapsed in 20 patients (83.3%) and stabilized in 4 (16.7%).

CONCLUSIONS

The extra-arachnoidal CCD is a safe and effective treatment for syringomyelia associated with Chiari I malformation in adults without intraoperative evidence of adhesive arachnoiditis. However a larger number of patients and longer follow-up will be necessary to determine the efficacy of extra-arachnoidal CCD.

Relevance of surgical strategies for the management of pediatric Chiari type I malformation

OBJECTIVE

In face of continuing controversy to the optimal treatment of Chiari type I malformation, the authors analyzed three different surgical strategies.

MATERIALS AND METHODS

Sixty patients (30 boys and 30 girls, mean age 8.2 years) presented with clinical Chiari malformation. Additional syringomyelia was present in 24 children, whereas cine flow studies showed no flow in the craniocervical junction in 48 children. All patients underwent a limited occipital craniectomy; a duraplasty was performed in 21 cases; and additional tonsillar reduction was performed in 19 cases. Clinical improvement was seen in 24 patients who underwent posterior decompression with or without duraplasty. In the tonsillar group, clinical improvement was evident in 18 patients.

CONCLUSIONS

Duraplasty and tonsillar reduction were equally effective but significantly better than bone decompression alone. Among patients with syringomyelia, tonsillar reduction was associated with a significantly better outcome. Postoperative flow studies improved in 39 patients but did not correlate to the clinical outcome.

Subarachnoid pressure—dependent change in syrinx size in a patient with syringomyelia associated with adhesive arachnoiditis

✓ The pathophysiology of syringomyelia is still not well understood. Current prevailing theories involve the assumption that cerebrospinal fluid (CSF) flows into the syrinx from the subarachnoid space through the perivascular space of Virchow—Robin. Reported here is the case of a patient with syringomyelia in which this course is clearly contradicted.

This patient with a holocord syrinx associated with adhesive arachnoiditis was treated 3 years previously with insertion of a subarachnoid—peritoneal shunt and had recently experienced worsening myelopathy. On surgical exploration, the shunt system was functioning normally. The medium-pressure shunt valve was replaced with an adjustable valve with a higher closing pressure setting, thus increasing the CSF pressure in the subarachnoid space. Contrary to prevailing theories, this procedure markedly reduced the size of the syrinx.

This case provides direct evidence that the syrinx size is inversely related to subarachnoid CSF pressure and supports the hypothesis that the pressure gradient across the spinal cord parenchyma is the force that generates syringes in syringomyelia.

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.

A case of Arnold–Chiari syndrome with flaccid paralysis and huge syringomyelia

STUDY DESIGN

A case report.

SETTING

Department of Orthopaedic Surgery, Shiga University of Medical Science, Japan.

PATIENT

A 13-year-old woman presented progressive weakness in the lower extremities, with predominance on the right. Magnetic resonance (MR) imaging revealed a huge syrinx. The patient also showed scoliosis, cleft palate, hearing impairment, excessive sweating, hairiness, dural ectasia, and malformation of the skull. METHOD AND OBJECTIVES: We treated a very rare case of Arnold-Chiari syndrome, which presented with flaccid paralysis. Methods of differential diagnosis and suitable treatment are discussed.

RESULTS AND CONCLUSION

Both the syrinx and muscle strength were quickly improved following placement of a syringo-peritoneal (S-P) shunt, after which the patient recovered the ability to walk. However, transient hypesthesia in the right hand occurred after the operation. The syrinx around the conus was thought to play a crucial role in the etiology of the patient case, which showed unique symptoms.

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.

Retrospective study of surgery-related outcomes in patients with syringomyelia associated with Chiari I malformation: clinical significance of changes in the size and localization of syrinx on pain relief

Object. Pain is one of the major symptoms in patients with syringomyelia; however, its origin is not fully understood, and postoperative improvement of pain is difficult to predict. The objectives of this study were to assess the surgery-related results obtained in patients who underwent treatment for syringomyelia associated with Chiari I malformation, particularly related to pain status, and to identify factors that may influence improvement in postoperative pain by comparing pre- and postoperative magnetic resonance (MR) imaging findings.

Methods. The correlation between pre- and postoperative changes in the size and the location of the syrinx and pain improvement was investigated in 25 patients. The shapes of the syringes were classified into three types: central, enlarged, and deviated. In most cases in which the syrinx deviated toward the posterolateral aspect of the spinal cord at the level corresponding to dermatomal distribution of preoperative pain, the lesion remained at the same position postoperatively, and improvement in pain was poor. On the other hand, enlarged-type syringes were the most frequently observed prior to surgery, exhibited diverse changes postoperatively, and improvement in pain status was difficult to predict. When postoperative MR imaging revealed a transformation to the deviated type, poor pain improvement was noted.

Conclusions. Neurons in the dorsal horn were thought to be involved in the development of pain as a result of the deafferentiation mechanism in cases of syringomyelia.

Hiccups Attributable to Syringobulbia and/or Syringomyelia Associated with a Chiari I Malformation: Case Report

OBJECTIVE AND IMPORTANCE

Approximately 20 to 50% of patients with syringomyelia associated with Chiari malformations exhibit cranial nerve or cerebellar symptoms. However, hiccups represent a rare clinical manifestation of this disorder. We report a case of intractable hiccups resulting from syringobulbia associated with a Chiari I malformation, which was successfully treated with foramen magnum decompression.

CLINICAL PRESENTATION

We report the case of a patient who presented with syringomyelia and syringobulbia associated with a Chiari I malformation, manifested as intractable hiccups and neurological deficits. Magnetic resonance imaging scans demonstrated syringobulbia in the dorsal medullary region and a large cervical syrinx from C2 to C6–C7, associated with a Chiari I malformation.

INTERVENTION

Foramen magnum decompression and a C1 laminectomy were performed. One month later, the intractable hiccups disappeared and the neurological symptoms demonstrated improvement.

CONCLUSION

Postoperative magnetic resonance imaging scans demonstrated enlargement of the subarachnoid space in the posterior fossa and disappearance of the syringobulbia. There has been no recurrence of intractable hiccups and syringobulbia in 6 months after surgery. Magnetic resonance imaging of the brainstem is an important diagnostic procedure for intractable hiccups, because syringobulbia associated with a Chiari malformation represents a surgically treatable disorder, although the incidence is low.

Clinical outcomes in patients with Chiari I malformation: a review of 27 cases

BACKGROUND

Chiari I malformation is a congenital maldevelopment defined as downward herniation of the cerebellar tonsils through the foramen magnum. It has been treated using a variety of surgical procedures. Surgical outcomes have been reported with varying results throughout the literature.

METHODS

We retrospectively reviewed 27 patients with Chiari I malformation operated at the University Hospital during a 9-year period from 1988 to 1997. We assessed preoperative and postoperative signs and symptoms in all the patients including headache, neck pain, nystagmus, vertigo, weakness, spasticity, atrophy, numbness, pain and temperature dissociation, diplopia, dysphagia, and sphincter dysfunction. Each patient was analyzed to determine if there was an arrest in the progression of the disease after surgical intervention.

RESULTS

Syringomyelia was present in 59% of the patients. Only 1 patient who presented with neck pain improved. One patient reported new onset headache, and one patient described his headache resolved. Vertigo resolved in three patients; two patients stated mild improvement, and one patient reported worsening. Nystagmus improved or resolved in six patients. Weakness improved in only two patients who did not have syringomyelia. Dysphagia improved in two patients, and in the others it remained unchanged. Diplopia, spasticity, atrophy, and numbness remained unchanged.

CONCLUSIONS

Our study provides evidence that the main benefit of the surgical management in patients with Chiari I malformation with or without syringomyelia is to arrest the progression of the disease.

Hypothesis on the pathophysiology of syringomyelia based on simulation of cerebrospinal fluid dynamics

OBJECTIVES

Despite many hypotheses, the pathophysiology of syringomyelia is still not well understood. In this report, the authors propose a hypothesis based on analysis of cerebrospinal fluid dynamics in the spine.

METHODS

An electric circuit model of the CSF dynamics of the spine was constructed based on a technique of computational fluid mechanics. With this model, the authors calculated how a pulsatile CSF wave coming from the cranial side is propagated along the spinal cord.

RESULTS

Reducing the temporary fluid storage capacity of the cisterna magna dramatically increased the pressure wave propagated along the central canal. The peak of this pressure wave resided in the mid-portion of the spinal cord.

CONCLUSIONS

The following hypotheses are proposed. The cisterna magna functions as a shock absorber against the pulsatile CSF waves coming from the cranial side. The loss of shock absorbing capacity of the cisterna magna and subsequent increase of central canal wall pressure leads to syrinx formation in patients with Chiari I malformation.

The role of cine flow MRI in children with Chiari I malformation

INTRODUCTION

Since the introduction of MRI, the incidence of Chiari I malformations (cerebellar tonsils ectopia) has increased. The clinical significance of this finding remains questionable in some instances. Recently, cine flow MRI has added to the understanding of the dynamics of cerebrospinal fluid at the craniocervical junction and to the pathophysiology of the Chiari I malformation. The present study attempts to analyze the role of cine flow MRI in Chiari I malformations.

MATERIALS AND METHODS

Between January 1990 and December 2000, 24 patients were identified who met the following inclusion criteria: patients diagnosed with Chiari I malformation who had had an MRI of the brain including the craniocervical junction, clinical follow-up for at least six months, and cine flow studies had to have been performed pre- and postoperatively. The cine flow studies were repeated during follow-up if the patients were not surgical candidates. Patients harboring intracranial space occupying lesions or lumboperitoneal shunts were excluded. Sixteen of the 24 selected patients underwent 18 operations and 8 were followed conservatively. There was a wide variation in clinical presentations. Twelve patients had cerebellar tonsils protruding more than 5 mm below the foramen magnum, and in 12 patients the descent of the cerebellar tonsils was less than 5 mm. Despite this difference in the degree of protrusion, there was no significant difference in clinical presentation. The cisterna magna was small or absent in 20 patients with sluggish cine flow posteriorly, 19 of whom were symptomatic, in contrast to 1 symptomatic patient who had satisfactory cine flow.

RESULTS

All patients with Chiari I malformation and an associated cervical syrinx had absent cine flow at the craniovertebral junction, and this finding was statistically significant. There was a good correlation between the clinical presentation and cine flow preoperatively, and between clinical improvement and cine flow postoperatively. Patients with Chiari I malformation, cervical syrinx, and absent cine flow preoperatively improved after suboccipital decompression and duroplasty. Patients with Chiari I malformations without syrinx and absent cine flow underwent suboccipital bony decompression alone and had satisfactory outcomes.

Tonsillectomy without craniectomy for the management of infantile Chiari I malformation

OBJECT

The authors report their experience with 15 pediatric patients who underwent resection or shrinkage of the cerebellar tonsils without craniectomy or laminectomy, for the management of Chiari I malformation.

METHODS

The procedure was performed in six boys and nine girls with a mean age of 10 years. Thirteen patients presented with the congenital form of this disorder and two patients with Chiari I malformation caused by lumboperitoneal shunting. Clinical complaints included headaches (seven patients), scoliosis (four patients), numbness of the extremities (four patients), and upper-limb weakness (two patients). Two patients presented with failure to thrive and one with vocal cord palsy. Eight patients (six girls and two boys) had syringomyelia. The patients' symptoms had developed within a mean time period of 21 months (range 1-70 months). In all patients the cerebellar tonsils were exposed through a dura mater-arachnoid incision at the occipitoatlantal space. In seven patients the tonsils were resected and in the remaining eight patients the tonsils were shrunk by coagulating their surfaces. All patients improved postoperatively. Gliosis with cortical atrophy was observed in the resected neural tissue. Syringomyelia was reduced in seven of eight patients. The mean length of the follow-up period was 7 months.

CONCLUSIONS

Removal of herniated cerebellar tonsils can be sufficient for alleviating symptoms in patients with Chiari I malformations.

Adult scoliosis in syringomyelia associated with Chiari I malformation

STUDY DESIGN

In adult syringomyelia associated with Chiari I malformation, the spinal deformity, the configuration of cerebellar tonsillar descent, the configuration of syrinx, and the clinical evaluation before and after surgery were investigated.

OBJECTIVES

To investigate the characteristics of the scoliosis in syringomyelia associated with Chiari I malformation.

SUMMARY OF BACKGROUND DATA

In previous studies, the clinical characteristics of pediatric scoliosis associated with syringomyelia have been reported.

METHODS

In this study, 42 patients with syringomyelia were treated. All the patients were 20 years of age or older. They were divided into three groups: Group 1 comprising those without scoliosis, Group 2 composed of those with scoliosis of 10 degrees or more but less than 20 degrees, and Group 3 consisting of those with scoliosis of 20 degrees or more. Investigations conducted with the three groups included determining the curve patterns of scoliosis, the degree of thoracic kyphosis, the configuration of cerebellar tonsillar descent, the configuration of syrinx, the morbidity period, and the clinical evaluation before and after surgery.

RESULTS

There were 12 patients in Group 1, 21 patients in Group 2, and 9 patients in Group 3. The concomitant rate of adult syringomyelia with scoliosis was 71.4%. As scoliosis advanced, the kyphotic angle also increased. The concordance in laterality between the cerebellar tonsil and curve convex was 70%. Findings showed that the more advanced the scoliosis was, the more aggravated the neurologic symptoms were, and the poorer the surgical outcomes tended to be.

CONCLUSIONS

In adult syringomyelia with scoliosis, the morbidity period is long, the syrinx is long, the neurologic symptoms are aggravated, and the surgical outcomes tend to be poor.

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.

Dural band pathology in syringomyelia with Chiari type I malformation

Surgical material taken from the 'outer layer' of thickened dura mater (dural band) at the craniovertebral junction of eight cases of syringomyelia with Chiari type I malformation was histologically examined in comparison with four autopsy cases as controls. The dural band was thickened and there were increased numbers of collagen fibers which showed fiber splitting, hyalinous nodule, calcification and/or ossification. These changes were not observed in the four control cases. Thus, it is suggested that the thickening of the dura mater may be a causative factor of syringomyelia with Chiari type I malformation. In addition, the histology of the thickened dura mater suggests the condition may be a consequence of birth injury in these patients.