Ventral Brainstem Compression Research Articles

Management of Ventral Brainstem Compression in Chiari Malformation Type I.

Craniovertebral junction (CVJ) abnormalities are associated with the Chiari malformation type I. These abnormalities may lead to ventral brainstem compression which can be reduced with traction and posterior reduction using instrumentation. In other cases, the irreducible CVJ pathology with persistent ventral brainstem compression requires ventral decompression. In all cases, a posterior extradural or extra-intradural decompression is required along with an occipitocervical fusion to maintain the reduced and realigned CVJ or stabilize the CVJ after a ventral decompression.

Revision Chiari Surgery in Young Children: Predictors and Outcomes

Introduction: Children aged 0–6 years with Chiari malformation (CM) often present with atypical symptoms and require revision surgery more often than older children. We studied characteristics and outcomes of CM patients in this age-group who underwent one or more revision surgeries to assess how often revision surgery is necessary and successful in this age-group. Methods: We retrospectively reviewed patients who were diagnosed with CM 1 or CM 1.5 and surgically treated with posterior fossa decompression (PFD) with or without duraplasty before their 7th birthday. Basic demographics, preoperative presentation, operative details, and postoperative outcomes were analyzed. Results: Forty patients (mean age 3.2 ± 1.7 years, 35% female) were reviewed. The most common presenting symptoms were headache, dysphagia, and respiratory problems. Eight patients required one or more revision surgeries 11.6 ± 7.6 months on average after their initial surgery. Comparing the revision and no revision groups, dysautonomia was significantly more common prior to initial surgery in the children requiring revision (37.5 vs. 3.1%, p = 0.02). The revision group also trended toward more dysphagia (75.0 vs. 46.9%, p = 0.24) and respiratory problems (75.0 vs. 40.6%, p = 0.12). The most frequent reasons for reoperation were symptom recurrence (6/8), residual posterior fossa compression (3/8), significant scar tissue formation (2/8), ventral brainstem compression (1/8), and suspected craniocervical instability (1/8). Of the 8 children undergoing reoperation, surgery achieved symptom resolution or improvement in 5, while 3 had unchanged symptoms. Two patients underwent a third surgery, after which 1 showed improvement and the other did not. This last patient showed short-term improvement after a fourth surgery but had symptom recurrence 12 months later. Discussion/Conclusion: Oropharyngeal and respiratory problems are particularly common in children aged 0–6 years with CM. Presentation with dysautonomia or other signs of brainstem compression will often predict an additional surgery will be needed after an initial PFD. Symptom recurrence is the most frequent reason for reoperation, and revision surgeries lead to improved clinical outcomes in the majority but not all of these young patients. Surgery in very young children is successful, but reoperation should be integrated into an up-front discussion algorithm particularly in children with severe symptoms.

Endoscopic transnasal/transoral odontoid resection in children: results of a combined neurosurgical and otolaryngological protocolized, institutional approach.

Odontogenic ventral brainstem compression can be a source of significant morbidity in patients with craniocervical disease. The most common methods for odontoidectomy are the transoral and endoscopic endonasal routes. In this study, the authors investigated the use of an institutional protocol for endoscopic transnasal/transoral odontoidectomy in the pediatric population. From 2007 to 2017, a multidisciplinary institutional protocol was developed and refined for the evaluation and treatment of pediatric patients requiring odontoidectomy. Preoperative assessment included airway evaluation, a sleep study (if indicated), discussion of possible tonsillectomy/adenoidectomy, and thorough imaging review by the neurosurgery and otolaryngology teams. Further preoperative anesthesia consultation was obtained for difficult airways. Intraoperatively, adenoidectomy was performed at the discretion of otolaryngology. The odontoidectomy was performed as a combined procedure. Primary posterior pharyngeal closure was performed by the otolaryngologist. The postoperative protocol called for immediate extubation, advancement to a soft diet at 24 hours, and no postoperative antibiotics. Outcome variables included time to extubation, operative time, estimated blood loss, hospital length of stay, and postoperative complications. A total of 13 patients underwent combined endoscopic transoral/transnasal odontoid resection with at least 3 years of follow-up. All patients had stable to improved neurological function in the postoperative setting. All patients were extubated immediately after the procedure. The average operative length was 201 ± 46 minutes, and the average estimated blood loss was 44.6 ± 40.0 ml. Nine of 13 patients underwent simultaneous tonsillectomy and adenoidectomy. The average hospital length of stay was 6.6 ± 5 days. The first patient in the series required revision surgery for removal of a small residual odontoid. One patient experienced pharyngeal flap dehiscence requiring revision. A protocolized, institutional approach for endoscopic transoral/transnasal odontoidectomy is described. The use of a combined, multidisciplinary approach leads to streamlined patient management and favorable outcomes in this complex patient population.

Optimizing Alignment Parameters During Craniocervical Stabilization and Fusion: A Technical Note.

Proper craniocervical alignment during craniocervical reduction, stabilization, and fusion optimizes cerebrospinal fluid (CSF) flow through the foramen magnum, establishes the appropriate “gaze angle”, avoids dysphagia and dyspnea, and, most importantly, normalizes the clival-axial angle (CXA) to reduce ventral brainstem compression. To illustrate the metrics of reduction that include CXA, posterior occipital cervical angle, orbital-axial or “gaze angle”, and mandible-axial angle, we present a video illustration of a patient presenting with signs and symptoms of the cervical medullary syndrome along with concordant radiographic findings of craniocervical instability as identified on dynamic imaging and through assessment of the CXA, Harris, and Grabb-Oakes measurements.

Changing Perception but Unaltered Reality: How Effective Is C1-C2 Fixation for Chiari Malformations without Instability?

The recently described C1-C2 fixation without foramen magnum decompression (FMD) for the management of Chiari malformations (CMs) has sparked a controversy. C1-C2 fixation has been reported to be more effective than traditional FMD. However, the results after such a procedure have not been as well validated. We assessed the efficacy of C1-C2 distraction and fusion without FMD in patients with CM and without demonstrable atlantoaxial instability. A total of 40 patients with CM had undergone C1-C2 distraction and fusion without FMD. The preoperative and follow-up clinicoradiological data were prospectively compared using the Klekamp neurologic score, visual analog scale, pBC2 index (ventral brainstem compression), and Vaquero index (syringomyelia). Of the 40 patients, 28 (70%) showed improvement in their neurological score and visual analog scale, 8remained in same status, 3 showed deterioration, and 1 died during the follow-up period. The clinical improvement did not correlate with the severity of ventral cervicomedullary compression or the presence of osseous deformities (assimilated C1 arch, platybasia and basilar invagination) despite the reduction in the mean pBC2 index (7.9 vs. 5.9). The syringomyelia had decreased in 51.7%, with a reduction in the Vaquero index at follow-up (0.48 vs. 0.38). The overall results after C1-C2 distraction and fusion for CM without instability were not exceptionally better and appeared to be similar to the outcomes reported with FMD. The neurological improvement seen in some patients had possibly resulted from indirect ventral decompression (due to distraction of C1-C2) rather than the stabilization itself. The presence of bony anomalies such as an assimilated C1 arch, platybasia, basilar invagination, and ventral brainstem compression did not significantly influence the outcomes.

Foramen magnum decompression without bone removal: C1-C2 posterior fixation for Chiari with congenital atlantoaxial dislocation/basilar invagination.

Background:Atlantoaxial dislocation (AAD) and basilar invagination (BI) may coexist with Chiari malformations (CM) and a small posterior fossa volume. These are typically treated with craniovertebral junction fusion and foramen magnum decompression (FMD). Here, we evaluated whether C1–C2 posterior reduction and fixation (which possibly opens up the ventral foramen magnum) would effectively treat AAD and CM without additionally performing FMD.Methods:This is a retrospective analysis of 38 patients with BI, AAD, and CM who underwent C1–C2 posterior reduction and fusion without FMD. Baseline and follow-up clinical, demographic, and radiological data were evaluated.Results:The vast majority of patients (91.9%) improved both clinically and radiographically following C1–C2 fixation alone; none later required direct FMD. Notably, AAD was irreducible in 25 (65.8%) patients. Preoperatively, syringomyelia was present in 28 (73.7%) patients and showed resolution. In 3 (8.1%) patients, resolution of syrinxes did not translate into clinical improvement. Of interest, 5 patients who sustained inadvertent dural lacerations exhibited transient postoperative neurological worsening.Conclusions:Posterior C1–C2 distraction and fusion alone effectively treated AAD, BI, accompanied by CM. The procedure sufficiently distracted the dens, reversed dural tenting, and restored the posterior fossa volume while relieving ventral brainstem compression making FMD unnecessary. Surgeons should, however, be aware that inadvertent dural lacerations might contribute to unwanted neurological deterioration.

Cervical medullary syndrome secondary to craniocervical instability and ventral brainstem compression in hereditary hypermobility connective tissue disorders: 5-year follow-up after craniocervical reduction, fusion, and stabilization

A great deal of literature has drawn attention to the “complex Chiari,” wherein the presence of instability or ventral brainstem compression prompts consideration for addressing both concerns at the time of surgery. This report addresses the clinical and radiological features and surgical outcomes in a consecutive series of subjects with hereditary connective tissue disorders (HCTD) and Chiari malformation. In 2011 and 2012, 22 consecutive patients with cervical medullary syndrome and geneticist-confirmed hereditary connective tissue disorder (HCTD), with Chiari malformation (type 1 or 0) and kyphotic clivo-axial angle (CXA) enrolled in the IRB-approved study (IRB# 10-036-06: GBMC). Two subjects were excluded on the basis of previous cranio-spinal fusion or unrelated medical issues. Symptoms, patient satisfaction, and work status were assessed by a third-party questionnaire, pain by visual analog scale (0–10/10), neurologic exams by neurosurgeon, function by Karnofsky performance scale (KPS). Pre- and post-operative radiological measurements of clivo-axial angle (CXA), the Grabb-Mapstone-Oakes measurement, and Harris measurements were made independently by neuroradiologist, with pre- and post-operative imaging (MRI and CT), 10/20 with weight-bearing, flexion, and extension MRI. All subjects underwent open reduction, stabilization occiput to C2, and fusion with rib autograft. There was 100% follow-up (20/20) at 2 and 5 years. Patients were satisfied with the surgery and would do it again given the same circumstances (100%). Statistically significant improvement was seen with headache (8.2/10 pre-op to 4.5/10 post-op, p < 0.001, vertigo (92%), imbalance (82%), dysarthria (80%), dizziness (70%), memory problems (69%), walking problems (69%), function (KPS) (p < 0.001). Neurological deficits improved in all subjects. The CXA average improved from 127° to 148° (p < 0.001). The Grabb-Oakes and Harris measurements returned to normal. Fusion occurred in 100%. There were no significant differences between the 2- and 5-year period. Two patients returned to surgery for a superficial wound infections, and two required transfusion. All patients who had rib harvests had pain related that procedure (3/10), which abated by 5 years. The results support the literature, that open reduction of the kyphotic CXA to lessen ventral brainstem deformity, and fusion/stabilization to restore stability in patients with HCTD is feasible, associated with a low surgical morbidity, and results in enduring improvement in pain and function. Rib harvest resulted in pain for several years in almost all subjects.

Limits of endoscopic endonasal approach for cranio-vertebral junction tumors.

The endoscopic endonasal approach has been recently proposed for cranio-vertebral junction lesions. The more common indication for this sagittal extension of the endonasal route is represented by odontoidectomy for irreducible ventral brainstem compression due to congenital or degenerative conditions. However, in an increasing number of studies its adoption for tumors involving the cranio-cervical junction has been reported. The aim of this study is to consider retrospectively our surgical series, focusing on the advantages and limits of this approach. Each consecutive case of tumor involving the cranio-vertebral junction since 2007 to 2017 treated through an endoscopic endonasal approach has been included. All patients undergone preoperative neurological examination and neuroimaging (magnetic resonance imaging [MRI] and computed tomography angiography). These examinations were repeated after 3 months and then annually. Complementary treatments, recurrence rate and clinical status at mean follow-up of 18±7.3 months were considered. Seven patients have been included in this study, mean age was of 47±17 years; male-to-female ratio was of 3:4. Series is composed by 6 chordomas and one foramen magnum meningioma. One patient had been already posteriorly stabilized for cranio-vertebral instability. Gross tumor removal was achieved in two cases, in the others a subtotal removal was demonstrated at postoperative MRI. One patient presented a transitory worsening of CN XII palsy, resolved within 3 months. For preoperative dysphagia and inhalation pneumonia, one case undergone tracheostomy and was fed with oro-gastric tube for 10 days. Three patients died for chordoma progression and at follow-up one presented a local recurrence. Despite our experience is preliminary, the endoscopic endonasal approach has resulted safe for cranio-cervical junction tumor with a reduced number of complications. It can give a straight and direct trajectory to this deep region. We suggest that lateral extension of the tumor beyond the plane of cranial nerves is a limit for this approach, as well as an inferior expansion caudal to C1. Larger series and longer follow-up are required to assess the proper indications of this approach.

Radiological evolution of peri-odontoid pannus in a patient with Chiari I malformation: a case-based review

The Chiari I malformation (CIM) is commonly encountered by neurosurgeons and can have different etiologies and clinical presentations. We report a CIM patient who presented with symptoms of ventral brain stem compression and was found to have a large peri-odontoid pannus. Posterior fossa decompression was performed with a planned second-stage odontoidectomy. However, at the 6-month follow-up, postoperative images demonstrated a mostly resolved pannus and improvement of the brain stem compression symptoms, and the patient progressed uneventfully without the need for odontoidectomy. This case illustrates the resolution of a significant and symptomatic peri-odontoid pannus in a patient with CIM without craniocervical fusion or odontoidectomy. Such a case indicates that not all peri-odontoid pannus formations in CIM patients are due to hypermobility at the craniocervical junction.

Analysis and interrater reliability of pB-C2 using MRI and CT: data from the Park-Reeves Syringomyelia Research Consortium on behalf of the Pediatric Craniocervical Society.

OBJECTIVE The distance to the ventral dura, perpendicular to the basion to C2 line (pB-C2), is commonly employed as a measure describing the anatomy of the craniovertebral junction. However, both the reliability among observers and the clinical utility of this measurement in the context of Chiari malformation Type I (CM-I) have been incompletely determined. METHODS Data were reviewed from the first 600 patients enrolled in the Park-Reeves Syringomyelia Research Consortium with CM-I and syringomyelia. Thirty-one cases were identified in which both CT and MRI studies were available for review. Three pediatric neurosurgeons independently determined pB-C2 values using common imaging sequences: MRI (T1-weighted and T2-weighted with and without the inclusion of retro-odontoid soft tissue) and CT. Values were compared and intraclass correlations were calculated among imaging modalities and observers. RESULTS Intraclass correlation of pB-C2 demonstrated strong agreement between observers (intraclass correlation coefficient [ICC] range 0.72-0.76). Measurement using T2-weighted MRI with the inclusion of retro-odontoid soft tissue showed no significant difference with measurement using T1-weighted MRI. Measurements using CT or T2-weighted MRI without retro-odontoid soft tissue differed by 1.6 mm (4.69 and 3.09 mm, respectively, p < 0.05) and were significantly shorter than those using the other 2 sequences. Conclusions pB-C2 can be measured reliably by multiple observers in the context of pediatric CM-I with syringomeyelia. Measurement using T2-weighted MRI excluding retro-odontoid soft tissue closely approximates the value obtained using CT, which may allow for the less frequent use of CT in this patient population. Measurement using T2-weighted MRI including retro-odontoid soft tissue or using T1-weighted MRI yields a more complete assessment of the extent of ventral brainstem compression, but its association with clinical outcomes requires further study.

Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review

There is growing recognition of the kyphotic clivo-axial angle (CXA) as an index of risk of brainstem deformity and craniocervical instability. This review of literature and prospective pilot study is the first to address the potential correlation between correction of the pathological CXA and postoperative clinical outcome. The CXA is a useful sentinel to alert the radiologist and surgeon to the possibility of brainstem deformity or instability. Ten adult subjects with ventral brainstem compression, radiographically manifest as a kyphotic CXA, underwent correction of deformity (normalization of the CXA) prior to fusion and occipito-cervical stabilization. The subjects were assessed preoperatively and at one, three, six, and twelve months after surgery, using established clinical metrics: the visual analog pain scale (VAS), American Spinal InjuryAssociation Impairment Scale (ASIA), Oswestry Neck Disability Index, SF 36, and Karnofsky Index. Parametric and non-parametric statistical tests were performed to correlate clinical outcome with CXA. No major complications were observed. Two patients showed pedicle screws adjacent to but not deforming the vertebral artery on post-operative CT scan. All clinical metrics showed statistically significant improvement. Mean CXA was normalized from 135.8° to 163.7°. Correction of abnormal CXA correlated with statistically significant clinical improvement in this cohort of patients. The study supports the thesis that the CXA maybe an important metric for predicting the risk of brainstem and upper spinal cord deformation. Further study is feasible and warranted.

Image-guided transoral approach in severe craniovertebral junction malformations at the golden age of endoscopy: Regarding 2 cases

IntroductionThe image-guided transoral approach (IGTOA) provides a safe exposure to skull base midline lesions and the ventral aspect of the craniovertebral junction (CVJ). The IGTOA has several advantages: the head being placed in the extended position, it decreases the brainstem angulation during surgery; the approach being done through the avascular median pharyngeal raphe, not only lowers the bleeding risk but also provides a direct access to the bony pathology and granulation tissue accessible only via the ventral route. Wide field exposure and maneuverability are necessary to deal with the entire ventral brainstem compression in case of severe CVJ malformation to safely perform partial clivectomy and odontoidectomy. Presentation of two casesWe illustrate the cases of two patients, 52-year-old and 42-year-old males, who presented with an impressive craniovertebral junction malformation, confirmed on CT and MRI images. They first underwent surgery by IGTOA, later completed by occipitocervical fixation. For the two patients, outcomes were assessed respectively at 4 and 5 years and showed satisfactory results both clinically and radiologically. ConclusionIn patients with marked ventral compression, the IGTOA provides direct and guided access to the anterior aspect of the CVJ and effective means for odontoidectomy and clivectomy. This approach is more easily maneuverable compared to the endonasal endoscopic approach. The IGTOA approach is quite a complex technique, requiring multidisciplinary skills, but it should primarily be used in difficult situations. We suggest that endonasal endoscopy is over-utilized. We consider that endoscopy should not be routinely performed and kept only for well-selected cases.

Clinical significance of changes in pB-C2 distance in patients with Chiari Type I malformations following posterior fossa decompression: a single-institution experience.

OBJECT The coexistence of Chiari malformation Type I (CM-I) and ventral brainstem compression (VBSC) has been well documented, but the change in VBSC after posterior fossa decompression (PFD) has undergone little investigation. In this study the authors evaluated VBSC in patients with CM-I and determined the change in VBSC after PFD, correlating changes in VBSC with clinical status and the need for further intervention. METHODS Patients who underwent PFD for CM-I by the senior author from November 2005 to January 2013 with complete radiological records were included in the analysis. The following data were obtained: objective measure of VBSC (pB-C2 distance); relationship of odontoid to Chamberlain's, McGregor's, McRae's, and Wackenheim's lines; clival length; foramen magnum diameter; and basal angle. Statistical analyses were performed using paired t-tests and a mixed-effects ANOVA model. RESULTS Thirty-one patients were included in the analysis. The mean age of the cohort was 10.0 years. There was a small but statistically significant increase in pB-C2 postoperatively (0.5 mm, p < 0.0001, mixed-effects ANOVA). Eleven patients had postoperative pB-C2 values greater than 9 mm. The mean distance from the odontoid tip to Wackenheim's line did not change after PFD, signifying postoperative occipitocervical stability. No patients underwent transoral odontoidectomy or occipitocervical fusion. No patients experienced clinical deterioration after PFD. CONCLUSIONS The increase in pB-C2 in patients undergoing PFD may occur as a result of releasing the posterior vector on the ventral dura, allowing it to relax posteriorly. This increase appears to be well-tolerated, and a postoperative pB-C2 measurement of more than 9 mm in light of stable craniocervical metrics and a nonworsened clinical examination does not warrant further intervention.

Pure Endoscopic Endonasal Odontoidectomy for Basilar Impression

Introduction: Odontoidectomy is often required to treat basilar impression with compression of the brainstem or cervical spinal cord. The transoral resection is the approach most often used. However, it is related with significant morbidity. Recently, there is a growing interest in the expanded endoscopic endonasal corridor to approach the craniocervical junction. Study Design: We present our four initial cases of pure endoscopic endonasal odontoidectomy for the treatment of basilar impression. Results: Three women and one man were treated between 47 and 70 years old. All patients presented with long-lasting history of severe gait ataxia and less frequently, neck pain, tinnitus, dysphagia, and tongue fibrillation. The procedure was divided in two operative settings (same operative time). First, it was performed the endoscopic endonasal approach, grafting of nasoseptal flap (Hadad-Bassagasteguy type), dissection of the clival region, removal of the anterior arch of C1 and the dens of C2. Afterward the patient was turned and an occipital-cervical fixation (occiput to lateral masses of C2-C3-C4) was performed. In all patients there was a substantial improvement in gait ataxia (3-year follow-up). No major morbidity or mortality was reported. Conclusion: The endoscopic approach is safe and effective to treat ventral brainstem compression due to basilar impression in comparison with the classic transoral approach.

Complex Chiari malformations in children: an analysis of preoperative risk factors for occipitocervical fusion

Chiari malformation Type I (CM-I) is a congenital anomaly often treated by decompressive surgery. Patients who fail to respond to standard surgical management often have complex anomalies of the craniovertebral junction and brainstem compression, requiring reduction and occipitocervical fusion. The authors hypothesized that a subgroup of "complex" patients defined by specific radiographic risk factors may have a higher rate of requiring occipitocervical fusion. A retrospective review was conducted of clinical and radiographic data in pediatric patients undergoing surgery for CM-I between 1995 and 2010. The following radiographic criteria were identified: scoliosis, syringomyelia, CM Type 1.5, medullary kinking, basilar invagination, tonsillar descent, craniocervical angulation (clivoaxial angle [CXA] < 125°), and ventral brainstem compression (pB-C2 ≥ 9 mm). A multivariate Cox regression analysis was used to determine the independent association between occipitocervical fusion and each variable. Of the 206 patients who underwent CM decompression with or without occipitocervical fusion during the study period, 101 had preoperative imaging available for review and formed the study population. Mean age at surgery was 9.1 years, and mean follow-up was 2.3 years. Eighty-two patients underwent suboccipital decompression alone (mean age 8.7 years). Nineteen patients underwent occipitocervical fusion (mean age 11.1 years), either as part of the initial surgical procedure or in a delayed fashion. Factors demonstrating a significantly increased risk of requiring fusion were basilar invagination (HR 9.8, 95% CI 2.2-44.2), CM 1.5 (HR 14.7, 95% CI 1.8-122.5), and CXA < 125° (HR 3.9, 95% CI 1.2-12.6). Patients presenting with basilar invagination, CM 1.5, and CXA < 125° are at increased risk of requiring an occipitocervical fusion procedure either as an adjunct to initial surgical decompression or in a delayed fashion. Patients and their families should be counseled in regard to these findings as part of a preoperative CM evaluation.

Transnasal odontoid resection followed by posterior decompression and occipitocervical fusion in children with Chiari malformation Type I and ventral brainstem compression

In rare cases, children with a Chiari malformation Type I (CM-I) suffer from concomitant, irreducible, ventral brainstem compression that may result in cranial neuropathies or brainstem dysfunction. In these circumstances, a 360 degrees decompression supplemented by posterior stabilization and fusion is required. In this report, the authors present the first experience with using an endoscopic transnasal corridor to accomplish ventral decompression in children with CM-I that is complicated by ventral brainstem compression. Two children presented with a combination of occipital headaches, swallowing dysfunction, myelopathy, and/or progressive scoliosis. Imaging studies demonstrated CM-I with severely retroflexed odontoid processes and ventral brainstem compression. Both patients underwent an endoscopic transnasal approach for ventral decompression, followed by posterior decompression, expansive duraplasty, and occipital-cervical fusion. In both patients the endoscopic transnasal approach provided excellent ventral access to decompress the brainstem. When compared with the transoral approach, endoscopic transnasal access presents 4 potential advantages: 1) excellent prevertebral exposure in patients with small oral cavities; 2) a surgical corridor located above the hard palate to decompress rostral pathological entities more easily; 3) avoidance of the oral trauma and edema that follows oral retractor placement; and 4) avoidance of splitting the soft or hard palate in patients with oral-palatal dysfunction from ventral brainstem compression. The endoscopic transnasal approach is atraumatic to the oral cavity, and offers a more superior region of exposure when compared with the standard transoral approach. Depending on their comfort level with endoscopic surgical techniques, pediatric neurosurgeons should consider this approach in children with pathological entities requiring ventral brainstem decompression.

Gamma knife radiosurgical management of petroclival meningiomas results and indications.

Surgical treatment of petroclival meningiomas remains challenging. In order to refine indications for the use of stereotactic radiosurgery in the treatment of these tumours, we retrospectively evaluated our experience in this field. Thirty-two patients harboring a petroclival meningioma were treated consecutively using a Gamma knife between December 92 and June 1998. Eight patients underwent radiosurgery after one or more attempted surgical removals and 24 had radiosurgery as the primary treatment. The main symptoms before radiosurgery were cranial nerve palsies, including a sixth nerve deficit in 10 patients and a trigeminal nerve disturbance in 9. All patients underwent a conformal multi-isocentric treatment (mean isocenter's number 8.8) and the dose delivered at the tumour margin ranged from 10 to 15 Gy (mean dose 13 Gy). The duration of follow-up varied from 24 to 118 months (mean clinical follow-up 56 months, mean radiological follow-up 52.6 months). All 32 patients survived. The tumour volume remained unchanged in 28 patients and decreased slightly in 4. Neurological status worsened permanently in 2 patients with a delayed hemiparesis due to focal pontine infarction. These complications were associated with large meningiomas with vascular involvement and ventral brainstem compression, and occurred at the very early stage of our experience. At last follow-up, preoperative fifth or sixth cranial nerve deficits had improved or recovered in 13 out of 19 patients and any delayed worsening or new cranial nerve deficits were not observed after radiosurgery. Stereotactic radiosurgery with a Gamma knife provides effective management of small to middle sized petroclival meningiomas and is an alternative to microsurgery. Careful selection of patients and use of major technical refinements should improve the safety of this treatment.

Combined anterior and posterior approach for managing basilar invagination associated with type I Chiari malformation.

Ventral brainstem compression is common in patients with basilar invagination associated with type I Chiari malformation. The aim of this study was to investigate the reliability of a combined one-session anterior-posterior surgical approach for these patients. Nine patients underwent transoral odontoidectomy, posterior foramen magnum decompression, occipitocervical fixation, and bone grafting. All but two patients had ventral and dorsal operations in one surgical sitting. One of these two individuals had previously undergone posterior decompressive surgery at another hospital, but his condition had deteriorated rapidly afterward. The mean follow-up time was 19 months (range, 14-30 months). There was no mortality and no significant morbidity in this series. All but one of the patients showed significant improvement in their symptoms. Chiari malformations have a surprisingly high association with basilar invagination, and patients may have symptoms in both conditions. If there is a marked anterior compression, anterior transoral and posterior decompression, fusion, and instrumentation is an optimal strategy for treating patients with basilar invagination associated with type I Chiari malformation.

Ventral Brain Stem Compression in Pediatric and Young Adult Patients with Chiari I Malformations

Ventral Brain Stem Compression in Pediatric and Young Adult Patients with Chiari I Malformations

Ventral Brain Stem Compression in Pediatric and Young Adult Patients with Chiari I Malformations

Ventral Brain Stem Compression in Pediatric and Young Adult Patients with Chiari I Malformations