Surgery for basilar invagination with and without Chiari I malformation.

OBJECTIVE: The surgical treatment for Chiari I malformation and basilar invagination has been discussed with great controversy in recent years. This paper presents a treatment algorithm for these disorders based on radiological features, intraoperative findings, and analyses of long-term outcomes. METHODS: Eight-five operations for 82 patients (mean ± SD age 40 ± 18 years; range 9-75 years) with basilar invagination were evaluated, with a mean follow-up of 57 ± 55 months. Apart from the radiological features and intraoperative findings, findings on neurological examinations before and after surgery were analyzed. Long-term outcomes were evaluated with Kaplan-Meier statistics. All 77 patients with a Chiari I malformation underwent foramen magnum decompression with arachnoid dissection and duraplasty. Patients with ventral compression by the odontoid peg were managed with posterior realignment and C1-2 fusion. Patients without ventral compression did not undergo C1-2 fusion unless radiological or clinical signs of instability were detected. RESULTS: Thirty-three patients without ventral compression or instability underwent foramen magnum decompression without additional fusion, whereas 52 operations on 49 patients involved posterior fusion at C0-2 or C1-2 after realignment of ventral compression and/or treatment of C1-2 instability. Postoperatively, gait ataxia, swallowing functions, and suboccipital pain improved significantly in both treatment groups. In total, 79% and 73% of patients reported that their condition improved after foramen magnum decompression alone and after fusion with or without foramen magnum decompression, respectively. Progression-free survival rates at 10 years were 83% and 81%, respectively. CONCLUSIONS: Among the patients with basilar invagination, a subgroup consisting of 40.2% of the included patients underwent successful long-term treatment with foramen magnum decompression alone and without additional fusion. This subgroup was characterized by the absence of a ventral compression and no atlantoaxial dislocation or other signs of craniocervical instability. The remainder of patients underwent C1-2 fusion with posterior realignment of ventral compression if required. In the presence of basilar invagination, Chiari I malformation should be treated with foramen magnum decompression and duraplasty.

Relevance of C1/2 Facet Configurations and Clivus-Canal-Angles for Adult Patients with Chiari I Malformation with and without Basilar Invagination.

OBJECTIVE: C1/2 facet configurations and clivus-canal-angles (CXAs) have been proposed as criteria for posterior fusion in Chiari I malformation (CMI). METHODS: Three-hundred and forty adults with CMI without basilar invagination (BI), 111 with CMI with BI, and 100 age- and sex-matched controls were studied using sagittal T2-weighted magnetic resonance imaging scans analyzing preoperative and postoperative values with their impact on progression-free survival rates. RESULTS: For CMI without BI, C1/2 facet configurations and CXA were similar to controls (142 ± 11 degrees and 144 ± 10 degrees, respectively) with low rates for posterior C1 displacements (7.1% and 10%, respectively). In CMI with BI, C1 facet displacements were common (54.9%) with lower CXA (120 ± 15 degrees). After foramen magnum decompression (FMD) in CMI without BI (n = 169), 1.8% developed posterior C1 facet displacements without CXA changes and a 97% progression-free survival rate for 10 years. In CMI with BI, patients without ventral compression or instability underwent FMD without fusion (n = 19). Among them, 5.3% developed a posterior C1 facet displacement without CXA changes and a 94% progression-free survival rate for 10 years. The remainder of CMI with BI underwent FMD with C1/2 fusion (n = 48). Among these, CXA values increased with 10-year progression-free survival rates of 74% and 93% with and without ventral compression, respectively. CONCLUSIONS: For adult CMI without BI, C1/2 facet configurations and CXA are irrelevant. FMD alone provides excellent long-term outcomes. In CMI with BI, anterior C1 facet displacements indicate C1/2 instability. Posterior fusions can be reserved for patients with ventral compression or C1/2 instability.

Diagnosis and treatment of Chiari malformation and syringomyelia in adults: international consensus document.

BACKGROUND: Syringomyelia and Chiari malformation are classified as rare diseases on Orphanet, but international guidelines on diagnostic criteria and case definition are missing. AIM OF THE STUDY: to reach a consensus among international experts on controversial issues in diagnosis and treatment of Chiari 1 malformation and syringomyelia in adults. METHODS: A multidisciplinary panel of the Chiari and Syringomyelia Consortium (4 neurosurgeons, 2 neurologists, 1 neuroradiologist, 1 pediatric neurologist) appointed an international Jury of experts to elaborate a consensus document. After an evidence-based review and further discussions, 63 draft statements grouped in 4 domains (definition and classification/planning/surgery/isolated syringomyelia) were formulated. A Jury of 32 experts in the field of diagnosis and treatment of Chiari and syringomyelia and patient representatives were invited to take part in a three-round Delphi process. The Jury received a structured questionnaire containing the 63 statements, each to be voted on a 4-point Likert-type scale and commented. Statements with agreement <75% were revised and entered round 2. Round 3 was face-to-face, during the Chiari Consensus Conference (Milan, November 2019). RESULTS: Thirty-one out of 32 Jury members (6 neurologists, 4 neuroradiologists, 19 neurosurgeons, and 2 patient association representatives) participated in the consensus. After round 2, a consensus was reached on 57/63 statements (90.5%). The six difficult statements were revised and voted in round 3, and the whole set of statements was further discussed and approved. CONCLUSIONS: The consensus document consists of 63 statements which benefited from expert discussion and fine-tuning, serving clinicians and researchers following adults with Chiari and syringomyelia.

Histological and intraoperative evaluations of the arachnoid in patients with Chiari I malformation.

BACKGROUND: Arachnoid dissection for decompression of Chiari I malformation is controversial. Whether arachnoid changes have an impact on the clinical course is not established. This paper documents the histological spectrum of arachnoid changes and evaluates correlations with preoperative, intraoperative, and postoperative data. METHOD: Arachnoid samples of 162 consecutive foramen magnum decompressions from 2006 to 2016 were studied. Arachnoid thickness and degrees of fibrosis and cellularity were determined with the examiner blinded for clinical data. Based on 145 first time decompressions, a histological classification for arachnoid features was developed. RESULTS: The arachnoid was thicker in secondary compared with primary decompressions (176.1 ± 158.2 µm vs. 35.9 ± 43.5 µm; p = 0.0026) and in adults compared to children (37.3 ± 45.3 µm vs. 21.8 ± 7.7 µm; p = 0.0007). In primary decompressions, arachnoid thickness, degrees of fibrosis, and cellularity followed a normal distribution with all features shifted significantly to higher grades in secondary decompressions. The histological classification correlated with the preoperative severity of gait ataxia, motor weakness, and sensory deficits, whereas it had no predictive power for postoperative short- or long-term results. By comparison, the intraoperative evaluation of arachnoid changes accounting for relationships between arachnoid and surrounding tissues showed higher correlations with preoperative symptoms and had significant predictive power for postoperative short- and long-term results. CONCLUSIONS: Histological changes of the arachnoid correlate with preoperative symptoms. Relationships between arachnoid and surrounding tissues show even higher correlations with predictive power for short- and long-term outcomes. These findings suggest a pathophysiological role for the arachnoid in Chiari I malformation.

Long-term course of anterior spinal cord herniation presenting with an upper motor neuron syndrome: case report illustrating diagnostic and therapeutic implications.

BACKGROUND: Anterior spinal cord herniation (aSCH) is a rare cause of myelopathy which may present as pure motor syndrome and mimic other degenerative diseases of the spinal cord. In slowly progressive cases, diagnosis may be impeded by equivocal imaging results and mistaken for evolving upper motor neuron disease. As early imaging studies are lacking, we aimed to provide a detailed description of imaging and neurophysiology findings in a patient with aSCH, focusing on the early symptomatic stages. CASE PRESENTATION: We here present the case of a 51-year old male patient with an episode of pain in the right trunk and a normal spinal MRI. After a symptom-free interval of 8 years, spasticity and paresis evolved in the right leg. There was subtle ventral displacement and posterior indentation of the thoracic spinal cord on MRI which, in retrospect, was missed as an early sign of aSCH. After another 3 years, symptoms spread to the left leg and a sensory deficit of the trunk became evident. Follow-up MRI now clearly showed an aSCH. Neurosurgical intervention consisted of remobilization of the herniated spinal cord and patch closure of the dura defect. Over the following years, motor and sensory symptoms partially improved. CONCLUSIONS: The history of this patient with aSCH illustrates the importance of careful longitudinal clinical follow-up with repeated imaging studies in progressive upper motor neuron syndromes. Specific attention should be paid to a history of truncal pain and to MRI findings of a ventrally displaced spinal cord. Neurosurgical intervention may halt the progression of herniation.

How Should Syringomyelia be Defined and Diagnosed?

OBJECTIVE: Syringomyelia is considered as a fluid-filled cavitation inside the spinal cord. However, there is no agreement whether a dilated central canal should be included under this heading or how glioependymal cysts, myelomalacias, or cystic tumors should be distinguished from syringomyelia. This article provides a definition of syringomyelia and guidelines for its diagnosis. METHODS: Between 1991 and 2015, of 3206 patients with spinal cord pathologies 2276 demonstrated cystic features. All patients underwent magnetic resonance imaging. Syringomyelia was differentiated from cystic intramedullary tumors, glioependymal cysts, myelomalacias, and dilatations of the central canal by clinical and radiologic criteria. RESULTS: A total of 1535 patients were diagnosed with syringomyelia, 635 with dilatations of the central canal, 52 with glioependymal cysts, 52 with mylomalacias, and 2 with cystic intramedullary spinal cord tumors. Additional neuroradiologic studies revealed the causes of syringomyelia. As a result 604 patients showed pathologies at the craniocervical junction leading to disturbances of cerebrospinal fluid (CSF) flow. The commonest was a Chiari I malformation in 543 patients. Nine hundred thirty-one patients presented with pathologies in the spinal canal. The commonest causes were spinal arachnopathies, leading to CSF flow obstructions in 533 patients, intramedullary tumors in 152 patients, and tethered cord syndromes in 69 patients. CONCLUSIONS: The diagnosis of syringomyelia should be reserved for patients with a fluid-filled cavity in the spinal cord related to either a disturbance of CSF flow, spinal cord tethering, or an intramedullary tumor. For patients in whom such a relation cannot be established, the diagnosis of syringomyelia should be withheld.

A New Classification for Pathologies of Spinal Meninges, Part 1: Dural Cysts, Dissections, and Ectasias.

BACKGROUND: The clinical significance of pathologies of the spinal dura is often unclear and their management controversial. OBJECTIVE: To classify spinal dural pathologies analogous to vascular aneurysms, present their symptoms and surgical results. METHODS: Among 1519 patients with spinal space-occupying lesions, 66 patients demonstrated dural pathologies. Neuroradiological and surgical features were reviewed and clinical data analyzed. RESULTS: Saccular dural diverticula (type I, n = 28) caused by defects of both dural layers, dissections between dural layers (type II, n = 29) due to defects of the inner layer, and dural ectasias (type III, n = 9) related to structural changes of the dura were distinguished. For all types, symptoms consisted of local pain followed by signs of radiculopathy or myelopathy, while one patient with dural ectasia presented a low-pressure syndrome and 10 patients with dural dissections additional spinal cord herniation. Type I and type II pathologies required occlusion of their dural defects via extradural (type I) or intradural (type II) approaches. For type III pathologies of the dural sac no surgery was recommended. Favorable results were obtained in all 14 patients with type I and 13 of 15 patients with type II pathologies undergoing surgery. CONCLUSION: The majority of dural pathologies involving root sleeves remain asymptomatic, while those of the dural sac commonly lead to pain and neurological symptoms. Type I and type II pathologies were treated with good long-term results occluding their dural defects, while ectasias of the dural sac (type III) were managed conservatively.

A New Classification for Pathologies of Spinal Meninges-Part 2: Primary and Secondary Intradural Arachnoid Cysts.

BACKGROUND: Spinal intradural arachnoid cysts are rare causes of radiculopathy or myelopathy. Treatment options include resection, fenestration, or cyst drainage. OBJECTIVE: To classify intradural spinal arachnoid cysts and present results of their treatment. METHODS: Among 1519 patients with spinal space occupying lesions, 130 patients demonstrated intradural arachnoid cysts. Neuroradiological and surgical features were reviewed and clinical data analyzed. RESULTS: Twenty-one patients presented arachnoid cysts as a result of an inflammatory leptomeningeal reaction related to meningitis, subarachnoid hemorrhage, intrathecal injections, intradural surgery, or trauma, ie, secondary cysts. For the remaining 109 patients, no such history could be elucidated, ie, primary cysts. Forty-six percent of primary and 86% of secondary cysts were associated with syringomyelia. Patients presented after an average history of 53 ± 88 months. There were 122 thoracic and 7 lumbar cysts plus 1 cervical cyst. Fifty-nine patients with primary and 15 patients with secondary cysts underwent laminotomies with complete or partial cyst resection and duraplasty. Mean follow-up was 57 ± 52 months. In the first postoperative year, profound improvements for primary cysts were noted, in contrast to marginal changes for secondary cysts. Progression-free survival for 10 years following surgery was determined as 83% for primary compared to 15% for secondary cysts. Despite differences in clinical presentation, progression-free survival was almost identical for patients with or without syringomyelia. CONCLUSIONS: Complete or partial resection leads to favorable short- and long-term results for primary arachnoid cysts. For secondary cysts, surgery can only provide clinical stabilization for a limited time due to the often extensive arachnoiditis.

Surgical treatment of multilevel cervical spondylosis in patients with or without a history of syringomyelia.

PURPOSE: Cervical spondylotic myelopathy (CSM) is the commonest spinal cord disease in adults. This paper compares patients who developed CSM after successful treatment of syringomyelia to those with CSM exclusively related to degenerative spinal disease. METHODS: In this prospective study, 70 consecutive patients with CSM and spondylotic changes in at least three levels underwent 73 operations between 2005 and 2015 (mean follow-up: 39 ± 36 months). Patients with treated syringomyelia (group A, n = 30) and those without (group B, n = 40) were distinguished. Japanese Orthopaedic Association (JOA) and European Myelopathy scores (EMS), Karnofksy scores, and scores for individual symptoms were compared. Long-term outcomes were analyzed with progression-free survival rates. RESULTS: Patients of group A were significantly younger with a significantly longer history and lower functional scores compared to group B. 59 laminectomies C3-C6 plus lateral mass fixations, six ventral decompressions with fusion, and eight combined approaches were performed. In both groups, mean JOA (A 9.5 ± 4.3-10.0 ± 4.7; B 11.3 ± 3.7-12.3 ± 4.3), EMS (A 11.4 ± 2.9-12.0 ± 3.1; B 12.2 ± 3.1-13.5 ± 3.3), and Karnofsky scores (A 59 ± 18-62 ± 18; B 68 ± 13-72 ± 15) increased in the first postoperative year with lower scores in group A throughout. Rates for progression-free survival for 5 years were similar in both groups (A 64.2%, B 65.6%). CONCLUSION: Patients with CSM benefit from decompressive surgery. Surgery should be advocated early for all symptomatic patients with a history of syringomyelia. These patients are at risk for diagnostic delay and worse postoperative results.

Spinal ependymomas. Part 1: Intramedullary ependymomas.

OBJECT Ependymomas represent the most common intramedullary tumor in adults. Despite their usually well-defined dissection plane, surgical morbidity has been documented to be considerably higher compared with other intramedullary entities. This study presents an analysis of risk factors for surgical morbidity and data on long-term results for intramedullary ependymomas. METHODS Among 1447 patients with tumors of the spinal canal treated between 1980 and 2014, 309 patients presented with intramedullary tumors. One hundred patients with intramedullary ependymomas underwent 102 operations. Mean age was 44 ± 15 years (range 8-74 years). Patients were followed by outpatient visits and questionnaires, with a mean follow-up of 77 ± 91 months. Short-term results were determined for individual symptoms and the McCormick Scale, whereas tumor recurrence rates were calculated with Kaplan-Meier statistics. RESULTS Compared with cervical ependymomas, those of the thoracic spine were associated with more severe motor deficits and gait problems at presentation. A total of 86.3% of patients with intramedullary ependymomas underwent gross-total resection (GTR). A low preoperative McCormick grade and first surgery were the strongest predictors for a GTR. Postoperatively, 67.6% of patients demonstrated a worse neurological state at discharge from the hospital. This deterioration was transient for 40.1% of the patients and permanent for 27.5%. In the long term, the McCormick grade remained unchanged from the preoperative grade in 74.5% of patients, while it was improved in 5.9% of patients and increased after surgery in 19.6% of patients. According to a multivariate analysis, the risk of permanent morbidity increased with a thoracic level of the ependymoma, advanced age, a long clinical history, presence of a tumor hemorrhage, and surgery on a recurrent tumor. In the long term, tumor recurrence rates correlated significantly with the amount of resection (4.2% and 18.5% in 20 years after GTR and partial resections, respectively). Postoperative neuropathic pain syndromes affected 37.0% of patients, whereas 4% demonstrated a postoperative myelopathy related to cord tethering at the level of surgery. CONCLUSIONS Intramedullary ependymomas are tumors best treated surgically. A complete resection indicates cure for the overwhelming majority of these patients. Surgery should be performed early by neurosurgeons who deal with these lesions on a regular basis to achieve high GTR rates. Permanent surgical morbidity varies most according to tumor location and patient age.

Spinal ependymomas. Part 2: Ependymomas of the filum terminale.

OBJECT Ependymomas of the filum terminale provide specific surgical challenges due to their often enormous size, contact with nerve roots of the cauda equina and conus, and potential for subarachnoid dissemination. This study presents treatment results for these tumors over a 30-year period. METHODS Among 1447 patients with tumors of the spinal canal treated between 1980 and 2014, 618 patients presented with extramedullary tumors. Of these, 42 patients (25 males, 17 females) demonstrated a myxopapillary ependymoma in the lumbosacral region. Thirty-four patients underwent 36 operations for 39 such tumors. The mean patient age was 38 ± 14 years (range 11-73 years), with an average clinical history of 37 ± 67 months. Patients were followed through outpatient visits and questionnaires, with a mean follow-up of 10 years (127 ± 100 months). Twenty-seven operations were performed to treat de novo tumors and the remainder were undertaken on recurrent tumors. Short-term results were determined for individual symptoms, and tumor recurrence rates were calculated with Kaplan-Meier statistical analyses. RESULTS Subarachnoid dissemination was observed in 11 patients and was related to previous surgery in 9 patients and associated with extensive tumors in 2 patients. Gross-total resections (GTR) were achieved in 28 operations (77.7%) and subtotal resections in the remainder. Subtotal resections were restricted to unencapsulated ependymomas (61.5%). Radiotherapy was employed after 6 operations on unencapsulated tumors, with 5 of these also demonstrating subarachnoid seeding. Permanent surgical morbidity affected 3 patients who experienced permanent worsening of bladder function, while 7 patients showed no postoperative changes, and the remaining 26 operations were followed by improvements. Long-term outcome depended on the amount of resection and the presence of a tumor capsule. Eight of 9 tumor recurrences affected unencapsulated tumors, of which 3 had undergone GTR. The overall recurrence rates were 6.6%, 19.0%, and 37.0% after 1, 10, and 20 years, respectively. For unencapsulated ependymomas, the corresponding rates were 15.6%, 32.5%, and 66.2% after 1, 10, and 20 years, respectively, with significantly lower rates of 9.1% after 10 and 20 years for encapsulated tumors. Postoperative radiotherapy tended to prolong the recurrence-free interval for patients with unencapsulated tumors. Five patient deaths occurred during follow-up, of which 2 deaths were tumor related and occurred at 216 and 287 months after surgery. CONCLUSION Extramedullary ependymomas are slow-growing tumors in the lumbosacral region, sometimes with an indolent course for long periods of time. Despite their delicate location and often enormous size, surgical morbidity in experienced hands is low, with good chances for postoperative clinical improvements and very low recurrence rates after GTR for encapsulated tumors. The role of postoperative radiotherapy remains controversial. Radiotherapy may be considered after incomplete resections of unencapsulated tumors and/or for patients with subarachnoid dissemination.

Chiari I malformation with and without basilar invagination: a comparative study.

OBJECT: Chiari I malformation is the most common craniocervical malformation. Its combination with basilar invagination in a significant proportion of patients is well established. This study presents surgical results for patients with Chiari I malformation with and without additional basilar invagination. METHOD: Three hundred twenty-three patients underwent 350 operations between 1985 and 2013 (mean age 43 ± 16 years, mean history of symptoms 64 ± 94 months). The clinical courses were documented with a score system for individual neurological symptoms for short-term results after 3 and 12 months. Long-term outcomes were analyzed with Kaplan-Meier statistics. The mean follow-up was 53 ± 58 months (the means are expressed ± SD). RESULTS: Patients with (n = 46) or without (n = 277) basilar invagination in addition to Chiari I malformation were identified. Patients with invagination were separated into groups: those with (n = 31) and without (n = 15) ventral compression by the odontoid in the foramen magnum. Of the 350 operations, 313 dealt with the craniospinal pathology, 28 surgeries were undertaken for degenerative diseases of the cervical spine, 3 were performed for hydrocephalus, and 6 syrinx catheters were removed for cord tethering. All craniospinal operations included a foramen magnum decompression with arachnoid dissection, opening of the fourth ventricle, and a duraplasty. In patients without invagination, craniospinal instability was detected in 4 individuals, who required additional craniospinal fusion. In patients with invagination but without ventral compression, no stabilization was added to the decompression. In all patients with ventral compression, craniospinal stabilization was performed with the foramen magnum decompression, except for 4 patients with mild ventral compression early in the series who underwent posterior decompression only. Among those with ventral compression, 9 patients with caudal cranial nerve dysfunctions underwent a combination of transoral decompression with posterior decompression and fusion. Within the 1st postoperative year, neurological scores improved for all symptoms in each patient group, with the most profound improvement for occipital pain. In the long term, late postoperative deteriorations were related to reobstruction of CSF flow in patients without invagination (18.3% in 10 years), whereas deteriorations in patients with invagination (24.9% in 10 years) were exclusively related either to instabilities becoming manifest after a foramen magnum decompression or to hardware failures. Results for ventral and posterior fusions for degenerative disc diseases in these patients indicated a trend for better long-term results with posterior operations. CONCLUSIONS: The great majority of patients with Chiari I malformations with or without basilar invagination report postoperative improvements with this management algorithm. There were no significant differences in short-term or long-term outcomes between these groups. Chiari I malformations without invagination and those with invaginations but without ventral compression can be managed by foramen magnum decompression alone. The majority of patients with ventral compression can be treated by posterior decompression, realignment, and stabilization, reserving anterior decompressions for patients with profound, symptomatic brainstem compression.

Treatment of basilar invagination.

PURPOSE: Basilar invagination is a rare craniocervical malformation which may lead to neurological deficits related to compression of brainstem and upper cervical cord as well as instability of the craniocervical junction. This study presents results of a treatment algorithm developed over a 20-year period focussing on anatomical findings, short-term and long-term outcomes. METHODS: 69 patients with basilar invagination (mean age 41 ± 18 years, history 64 ± 85 months) were encountered. The clinical courses were documented with a score system for individual neurological symptoms for short-term results after 3 and 12 months. Long-term outcomes were analyzed with Kaplan-Meier statistics. RESULTS: Patients with (n = 31) or without (n = 38) ventral compression were distinguished. 25 patients declined an operation, while 44 patients underwent 48 operations. Surgical management depended on the presence of ventral compression and segmentation anomalies between occiput and C3, signs of instability and presence of caudal cranial nerve dysfunctions. 16 patients without ventral compression underwent foramen magnum decompressions without fusion. 19 patients with ventral compression and abnormalities of segmentation or evidence of instability underwent a foramen magnum decompression with craniocervical (n = 18) or C1/2 (n = 1) stabilization. In nine patients with severe ventral compression and caudal cranial nerve deficits, a transoral resection of the odontoid was combined with a posterior decompression and fusion. Within the first postoperative year neurological scores improved for all symptoms in each patient group. In the long-term, postoperative deteriorations were related exclusively to instabilities either becoming manifest after a foramen magnum decompression in three or as a result of hardware failures in two patients. CONCLUSIONS: The great majority of patients with basilar invagination report postoperative improvements with this management algorithm. Most patients without ventral compression can be managed by foramen magnum decompression alone. The majority of patients with ventral compression can be treated by posterior decompression, realignment and stabilization alone, reserving anterior decompressions for patients with profound, symptomatic brainstem compression.

Treatment of intramedullary tumors: analysis of surgical morbidity and long-term results.

OBJECT: Surgery of intramedullary tumors is established as the treatment of choice for these challenging lesions. This study presents a detailed analysis of risk factors for surgical morbidity and data on long-term results for intramedullary tumors. METHODS: Among 1317 patients with tumors of the spinal canal treated between 1980 and 2012, 278 patients with intramedullary tumors are presented. A total of 225 of these patients underwent 246 operations for treatment of 250 tumors. The mean patient age was 41 ± 17 years (range 3 weeks to 83 years). Patients underwent follow-up through outpatient visits and questionnaires with a mean follow-up of 41 ± 53 months. Tumors were subdivided into 3 groups: displacing tumors (Type A, n = 162), infiltrating tumors (Type B, n = 80), and nonproliferating tumors (Type C, n = 8). A gross-total resection (GTR) was attempted for every tumor except for Type C lipomas. Participating surgeons were divided into 3 groups according to the number of operations they performed. Short-term results were determined for individual symptoms and the modified McCormick Scale, whereas tumor recurrence rates were calculated with Kaplan-Meier statistics. RESULTS: Overall, 83.3% of Type A tumors underwent GTR compared with 22.5% of Type B and none in Type C. Gross-total resection rates increased throughout the study period and correlated significantly with surgical experience. A worsened neurological state after surgery was seen in 61% of patients. This deterioration was transient in 41.5% and was a common observation after GTR. Permanent morbidity (19.5%) was lowest after GTR and correlated significantly with surgical experience and the preoperative neurological state. Further analysis showed that patients with tumors of thoracic levels, tumor hemorrhages, and malignant and recurrent tumors were at a higher risk for permanent morbidity. In the long term, tumor recurrence rates for ependymomas and benign astrocytomas correlated significantly with the amount of resection. Long-term morbidity affected 3.7% with a postoperative myelopathy related to cord tethering at the level of surgery and 21.9% in form of neuropathic pain syndromes. The rate of postsurgical cord tethering could be lowered significantly by using pia sutures after tumor resection. Neuropathic pain syndromes were more common after surgery for tumors with associated syringomyelia or those located in the cervical cord. CONCLUSIONS: Intramedullary tumors should be surgically treated as soon as neurological symptoms appear. Gross-total resection is possible for the majority of benign pathologies. Cervical tumors are associated with higher GTR and lower permanent morbidity rates compared with thoracic tumors. Surgery on intramedullary tumors should be performed by neurosurgeons who deal with these lesions on a regular basis as considerable experience is required to achieve high GTR rates and to limit rates of permanent morbidity.

Treatment of syringomyelia related to nontraumatic arachnoid pathologies of the spinal canal.

BACKGROUND: Disturbances of cerebrospinal fluid (CSF) flow are the commonest cause of syringomyelia. Spinal arachnopathies may lead to CSF flow obstructions but are difficult to diagnose. Consequently, associated syringomyelias are often categorized as idiopathic. OBJECTIVE: To present and analyze the diagnosis of and long-term outcomes in an observational study of patients with nontraumatic arachnopathies from 1991 to 2011. METHODS: A total of288 patients (mean age, 47 ± 15 years; follow-up, 54 ± 46 months) were evaluated. Decompression with arachnolysis, untethering, and duraplasty for restoration of CSF flow was recommended to patients with neurological progression. Neurological examinations, magnetic resonance images, and follow-up data were evaluated. Individual symptoms were analyzed during the first postoperative year, and long-term outcomes were analyzed with Kaplan-Meier statistics to determine rates of progression-free survival. RESULTS: In total,189 patients either refused an operation or were managed conservatively for lack of progression. Among 79 unoperated patients with follow-up information available for up to 8 years, 2 patients deteriorated. Ninety-nine patients with progressive symptoms underwent 116 operations: 108 decompressions and 8 other surgeries. Three months postoperatively, 53% considered their status improved and 37% were unchanged. In the long term, surgery on arachnopathies limited to 2 spinal segments was followed by progression-free survival for 78% over 10 years, in contrast to 31% with extensive arachnopathies. CONCLUSION: Surgery on nontraumatic arachnopathies related to syringomyelia should be reserved for patients with progressive symptoms. Arachnolysis, untethering, and duraplasty provide good long-term results for focal arachnopathies. For extensive pathologies with a history of subarachnoid hemorrhage or meningitis, treatment remains a major challenge.

Neurological deterioration after foramen magnum decompression for Chiari malformation type I: old or new pathology?

OBJECT: Decompression of the foramen magnum is widely accepted as the procedure of choice for patients with Chiari malformation Type I (CM-I). This study was undertaken to determine the mechanisms responsible for neurological deterioration after foramen magnum decompression and the results of secondary interventions. METHODS: Between 1987 and 2010, 559 patients with CM-I presented, 107 of whom had already undergone a foramen magnum decompression, which included a syrinx shunt in 27 patients. Forty patients who were neurologically stable did not undergo another operation. Sixty-seven patients with progressive symptoms received a recommendation for surgery, which was refused by 16 patients, while 51 patients underwent a total of 61 secondary operations. Hospital and outpatient records, radiographic studies, and intraoperative images were analyzed. Additional follow-up information was obtained by telephone calls and questionnaires. Short-term results were determined after 3 and 12 months, and long-term outcomes were evaluated using Kaplan-Meier statistics. RESULTS: Sixty-one secondary operations were performed after a foramen magnum decompression. Of these 61 operations, 15 involved spinal pathologies not related to the foramen magnum (spinal group), while 46 operations were required for a foramen magnum issue (foramen magnum group). Except for occipital pain and swallowing disturbances, the clinical course was comparable in both groups. In the spinal group, 5 syrinx shunt catheters were removed because of nerve root irritations or spinal cord tethering. Eight patients underwent a total of 10 operations on their cervical spine for radiculopathies or a myelopathy. No permanent surgical morbidity occurred in this group. In the foramen magnum group, 1 patient required a ventriculoperitoneal shunt for hydrocephalus 7 months after decompression. The remaining 45 secondary interventions were foramen magnum revisions, of which 10 were combined with craniocervical fusion. Intraoperatively, arachnoid scarring with obstruction of the foramen of Magendie was the most common finding. Complication rates for foramen magnum revisions were similar to first decompressions, whereas permanent surgical morbidity was higher at 8.9%. Postoperative clinical improvements were marginal in both surgical groups. With the exception of 1 patient who underwent syrinx catheter removal and had a history of postoperative meningitis, all patients in the spinal group were able to be stabilized neurologically. Long-term results in the foramen magnum group revealed clinical stabilizations in 66% for at least 5 years. CONCLUSIONS: Neurological deterioration in patients after a foramen magnum decompression for CM-I may be related to new spinal pathologies, craniocervical instability, or recurrent CSF flow obstruction at the foramen magnum. Whereas surgery for spinal pathologies is regularly followed by clinical stabilization, the rate of long-term success for foramen magnum revisions was limited to 66% for 5 years due to severe arachnoid scarring in a significant proportion of these patients. Therefore, foramen magnum revisions should be restricted to patients with progressive symptoms.

Treatment of posttraumatic syringomyelia.

OBJECT: This paper presents results of a prospective study for patients undergoing surgery for posttraumatic syringomyelia between 1991 and 2010. METHODS: A group of 137 patients with posttraumatic syringomyelia were evaluated (mean age 45 ± 13 years, mean follow-up 51 ± 51 months) with pre- and postoperative MRI and clinical examinations presenting in this period and followed prospectively by outpatient visits and questionnaires. Surgery was recommended for symptomatic patients with a progressive course. Short-term results were determined within 3 months of surgery, whereas long-term outcomes in terms of clinical recurrences were studied with Kaplan-Meier statistics. RESULTS: Three groups were distinguished according to the type of trauma: Group A, patients with spinal trauma but without cord injury (ASIA E, n = 37); Group B, patients with an incomplete cord injury (ASIA C or D, n = 55); and Group C, patients with complete loss of motor function or a complete cord injury (ASIA A or B, n = 45). Overall, 61 patients with progressive symptoms underwent 71 operations. Of these operations, 61 consisted of arachnolysis, untethering, and duraplasty at the trauma level (that is, decompression), while 4 ASIA A patients underwent a cordectomy. The remaining procedures consisted of placement of a thecoperitoneal shunt, 2 opiate pump placements, and 2 anterior and 1 posterior cervical decompression and fusion. Seventy-six patients were not treated surgically due to lack of neurological progression or refusal of an operation. Neurological symptoms remained stable for 10 years in 84% of the patients for whom surgery was not recommended due to lack of neurological progression. In contrast, 60% of those who declined recommended surgery had neurological progression within 5 years. For patients presenting with neurological progression, outcome was better with decompression. Postoperatively, 61% demonstrated a reduction of syrinx size. Although neurological symptoms generally remained unchanged after surgery, 47% of affected patients reported a postoperative improvement of their pain syndrome. After 3 months, 51% considered their postoperative status improved and 41% considered it unchanged. In the long-term, favorable results were obtained for Groups A and C with rates for neurological deterioration of 6% and 14% after 5 years, respectively. In Group B, this rate was considerably higher at 39%, because arachnolysis and untethering to preserve residual cord function could not be fully achieved in all patients. Cordectomy led to neurological improvement and syrinx collapse in all 4 patients. CONCLUSIONS: The technique of decompression with arachnolysis, untethering, and duraplasty at the level of the underlying trauma provides good long-term results for patients with progressive neurological symptoms following ASIA A, B and E injuries. Treatment of patients with posttraumatic syringomyelia after spinal cord injuries with preserved motor functions (ASIA C and D) remains a major challenge. Future studies will have to establish whether thecoperitoneal shunts would be a superior alternative for this subgroup.

Surgical treatment of Chiari I malformation--analysis of intraoperative findings, complications, and outcome for 371 foramen magnum decompressions.

BACKGROUND: Foramen magnum decompression is widely accepted as the treatment of choice for Chiari I malformation. However, important surgical details of the procedure are controversial. OBJECTIVE: This study analyzes 371 decompressions focusing on intraoperative findings, analysis of complications, and long-term outcomes. METHODS: Among 644 patients between 1985 and 2010, 359 patients underwent 371 decompressions. Surgery for symptomatic patients consisted of suboccipital craniectomy, C1 laminectomy, arachnoid dissection, and duraplasty. Short-term results were determined after 3 months; long-term outcomes were evaluated with Kaplan-Meier statistics. RESULTS: The mean age was 40 ± 16 years; mean follow-up was 49 ± 56 months; 75.8% demonstrated syringomyelia. The complication rate was 21.8% with permanent surgical morbidity of 3.2% and surgical mortality of 1.3%. Of the patients, 73.6% reported improvement after 3 months; 21% were unchanged. Overall, 14.3% demonstrated a neurological deterioration within 5 years and 15.4% within 10 years. The severity of neurological symptoms correlated with the grade of arachnoid pathology. Outcome data correlated with the number of previous decompressions, severity of arachnoid pathology, handling of the arachnoid, type of duraplasty, and surgical experience. First-time decompressions with arachnoid dissection and an alloplastic duraplasty resulted in surgical morbidity for 2.0%, a 0.9% mortality rate, postoperative improvement after 3 months for 82%, and neurological recurrence rates of 7% after 5 years and 8.7% after 10 years. CONCLUSION: Arachnoid pathology in Chiari I malformation has an impact on clinical symptoms and postoperative results. Decompressions with arachnoid dissection and an alloplastic duraplasty performed by surgeons experienced with this pathology offer a favorable long-term prognosis.