Foramen magnum decompression in an infant with homozygous achondroplasia

✓ Ten patients who had cervical myelopathy due to ossification of the posterior longitudinal ligament of the cervical spine are described. This disease is characterized by an abnormal longitudinal strip of ossified ligamentous tissue along the posterior margin of vertebrae from C-3 to C-6; the primary lesion appears to be a degeneration of the intervertebral disc. This distinct clinical, radiological, and pathological entity should be included in the differential diagnosis of cervical myelopathy. All 10 patients were treated by extensive decompressive laminectomy and multiple bilateral facetectomies, with or without foramen magnum decompression. The results were favorable, and postoperative myelography demonstrated dorsal migration of the entire dural contents.

Craniocervical decompression for cervicomedullary compression in pediatric patients with achondroplasia

Journal of Neurosurgery ◽

10.3171/jns.1990.73.3.0375 ◽

1990 ◽

Vol 73 (3) ◽

pp. 375-382 ◽

Cited By ~ 56

Author(s):

John Aryanpur ◽

Orest Hurko ◽

Clair Francomano ◽

Henry Wang ◽

Benjamin Carson

Keyword(s):

Pediatric Patients ◽

Foramen Magnum ◽

Respiratory Compromise ◽

Content Type ◽

Standardized Protocol ◽

Csf Leakage ◽

Upper Cervical ◽

Csf Diversion ◽

Respiratory Complaints ◽

Cervicomedullary Compression

✓ The congenital osseous abnormalities associated with achondroplasia include stenosis of the foramen magnum and the upper cervical spinal canal. In the pediatric achondroplastic patient, such stenosis may lead to cervicomedullary compression with serious sequelae, including paresis, hypertonia, delayed motor milestones, and respiratory compromise. Using a standardized protocol the authors have treated 15 young achondroplastic patients with documented cervicomedullary compression by craniocervical decompression and duroplasty. Following this procedure, significant improvement in presenting neurological or respiratory complaints was noted in all patients. The mortality rate in this series was zero. The major cause of morbidity associated with this procedure was perioperative cerebrospinal fluid (CSF) leakage from the surgical wound, presumably related to coexisting abnormalities of CSF dynamics. This problem was successfully managed by temporary or, when necessary, permanent CSF diversion procedures. It is concluded that craniocervical decompression is an effective and safe treatment for young achondroplastic patients with cervicomedullary compression.

A critical appraisal of drainage in syringomyelia

Journal of Neurosurgery ◽

10.3171/jns.1995.82.1.0001 ◽

1995 ◽

Vol 82 (1) ◽

pp. 1-10 ◽

Cited By ~ 145

Author(s):

Spiros Sgouros ◽

Bernard Williams

Keyword(s):

Subarachnoid Space ◽

Foramen Magnum ◽

Drainage Procedure ◽

Term Outcome ◽

Long Term Outcome ◽

Content Type ◽

Surgical Measures ◽

Fatal Hemorrhage ◽

Fine Print

✓ The use of drains in the treatment of syringomyelia has a simple and immediate appeal and has been practiced widely since the report of Abbe and Coley over 100 years ago. Good short-term results have been claimed in the past, but long-term outcome is largely unknown. An experience in Birmingham, England is reviewed in which 73 patients who had had some form of syrinx drainage procedure performed were subsequently followed up. In these cases, a total of 56 syringopleural and 14 syringosubarachnoid shunts had been inserted. Ten years after the operations, only 53.5% and 50% of the patients, respectively, continued to remain clinically stable. A 15.7% complication rate was recorded, including fatal hemorrhage, infection, and displacement of the drain from the pleural and syrinx cavities. At second operation or necropsy, at least 5% of shunts were discovered to be blocked. The effect of other drainage procedures that do not use artificial tubing, such as syringotomy and terminal ventriculostomy, was analyzed but found not to offer any substantial benefit. These results indicate that drainage procedures are not an effective solution to remedying the progressive, destructive nature of syringomyelia. It is suggested that, rather than attempting to drain the syrinx cavity, disabling the filling mechanism of the syrinx is more appropriate. Most forms of syringomyelia have a blockage at the level of the foramen magnum or in the subarachnoid space of the spine. Surgical measures that aim to reconstruct the continuity of the subarachnoid space at the site of the block are strongly recommended. Lowering the overall pressure of the cerebrospinal fluid is advocated when reestablishment of the pathways proves impossible. Syrinx drainage as an adjuvant to more physiological surgery may have a place in the treatment of syringomyelia. If two procedures are done at the same time, however, it is difficult to ascribe with certainty a success or failure, and it is suggested that the drainage procedure be reserved for a later attempt if the elective first operation fails.

Syringomyelia without hindbrain herniation: tight cisterna magna

Journal of Neurosurgery Spine ◽

10.3171/spi.2002.96.2.0239 ◽

2002 ◽

Vol 96 (2) ◽

pp. 239-249 ◽

Cited By ~ 10

Author(s):

Kazuhiko Kyoshima ◽

Takayuki Kuroyanagi ◽

Fusakazu Oya ◽

Yukihiro Kamijo ◽

Hossam El-Noamany ◽

...

Keyword(s):

Foramen Magnum ◽

Central Canal ◽

Foramen Magnum Decompression ◽

Ventricular Dilation ◽

Content Type ◽

Cisterna Magna ◽

Hindbrain Herniation ◽

Ventricle Size ◽

Idiopathic Syringomyelia ◽

Fine Print

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

Cervicomedullary compression in achondroplasia

Journal of Neurosurgery ◽

10.3171/jns.1994.81.1.0043 ◽

1994 ◽

Vol 81 (1) ◽

pp. 43-48 ◽

Cited By ~ 69

Author(s):

Timothy C. Ryken ◽

Arnold H. Menezes

Keyword(s):

Posterior Fossa ◽

Foramen Magnum ◽

Posterior Arch ◽

Posterior Fossa Decompression ◽

Duration Of Symptoms ◽

Content Type ◽

Cervicomedullary Junction ◽

Plain Films ◽

Cervicomedullary Compression ◽

Fine Print

✓ Six patients with achondroplasia and symptoms suggestive of cervicomedullary junction compression are reviewed; these included three females and three males, with an average age of 8 years (range 7 months to 30 years). The mean duration of symptoms prior to intervention was 1.9 years. Symptoms included occipitocervical pain, ataxia, incontinence, apnea, and respiratory arrest. Radiological investigations consisted of plain films with flexion and extension views, pluridirectional tomography, thin-section computerized tomography, and magnetic resonance imaging. Typical findings included marked foramen magnum stenosis, ventrolateral cervicomedullary junction compression secondary to central and paramesial basilar invagination, and dorsal cervicomedullary junction compression secondary to ligamentous hypertrophy and invagination of the posterior atlantal arch. All patients underwent posterior fossa decompression and atlantal laminectomy. Surgery consistently revealed marked dorsal and paramesial overgrowth of the rim of the foramen magnum, with thickening and invagination of the atlantal posterior arch and a dense fibrotic epidural band resulting in dorsal cervicomedullary compression. Intraoperative ultrasonography was used to determine the extent of decompression required. Three patients required duraplasty. Three patients had concurrent hydrocephalus, two of whom had undergone ventriculoperitoneal shunting prior to surgical decompression of the posterior fossa. One patient developed a pseudomeningocele postoperatively, requiring serial lumbar punctures before it resolved. No patient developed craniovertebral instability following decompression. Improvement or resolution of symptoms was noted in all patients, with an average follow-up period of 4.8 years. Thus, cervicomedullary compression in patients with achondroplasia can be successfully treated with dorsal decompression of the craniovertebral junction. Dense epidural fibrotic bands are frequently noted in these cases and must be aggressively released to ensure satisfactory decompression.

Tonsillar herniation: the rule rather than the exception after lumboperitoneal shunting in the pediatric population

Journal of Neurosurgery ◽

10.3171/jns.1993.78.4.0568 ◽

1993 ◽

Vol 78 (4) ◽

pp. 568-573 ◽

Cited By ~ 162

Author(s):

Paul D. Chumas ◽

Derek C. Armstrong ◽

James M. Drake ◽

Abhaya V. Kulkarni ◽

Harold J. Hoffman ◽

...

Keyword(s):

Morphological Changes ◽

Pediatric Population ◽

Pseudotumor Cerebri ◽

Foramen Magnum ◽

Tonsillar Herniation ◽

Content Type ◽

Asymptomatic Patients ◽

The Mean ◽

Sick Children ◽

Fine Print

✓ Although the development of tonsillar herniation (acquired Chiari malformation) in association with lumboperitoneal (LP) shunting is well recognized, it has previously been considered rare. In order to ascertain the incidence of this complication after LP shunting, the authors undertook a retrospective study of all patients in whom this form of shunt had been inserted between 1974 and 1991 at The Hospital for Sick Children, Toronto. In the 143 patients, the mean age at insertion was 3.3 years and the indications for shunt placement were hydrocephalus (81%), pseudotumor cerebri (7%), cerebrospinal fluid fistula (6%), and posterior fossa pseudomeningocele (6%). The mean follow-up period was 5.7 years, during which time there was one shunt-related death due to unsuspected tonsillar herniation. Five other patients developed symptomatic tonsillar herniation treated by suboccipital decompression. Review of all computerized tomography (CT) scans not degraded by artifact showed evidence of excess soft tissue at the level of the foramen magnum in 38 (70%) of 54 patients so studied. In order to confirm that this CT finding represented hindbrain herniation, sagittal and axial magnetic resonance (MR) images were obtained for 17 asymptomatic patients and revealed tonsillar herniation (range 2 to 21 mm) in 12 (70.6%). In addition, some of these asymptomatic patients had evidence of uncal herniation and mesencephalic distortion. Similarities and distinctions are drawn between the morphological changes occurring after LP shunting and those seen in association with the Chiari I and II malformations. Although less than 5% of this study population required treatment for tonsillar herniation, the incidence of this complication was high in asymptomatic patients; MR imaging surveillance for patients with LP shunts is therefore recommended.

Elucidating the pathophysiology of syringomyelia

Journal of Neurosurgery ◽

10.3171/jns.1999.91.4.0553 ◽

1999 ◽

Vol 91 (4) ◽

pp. 553-562 ◽

Cited By ~ 297

Author(s):

John D. Heiss ◽

Nicholas Patronas ◽

Hetty L. DeVroom ◽

Thomas Shawker ◽

Robert Ennis ◽

...

Keyword(s):

Mr Imaging ◽

Subarachnoid Space ◽

Foramen Magnum ◽

Chiari I Malformation ◽

Content Type ◽

Cine Mr ◽

Spinal Subarachnoid Space ◽

Chiari I ◽

Cerebellar Tonsils ◽

Fine Print

Object. Syringomyelia causes progressive myelopathy. Most patients with syringomyelia have a Chiari I malformation of the cerebellar tonsils. Determination of the pathophysiological mechanisms underlying the progression of syringomyelia associated with the Chiari I malformation should improve strategies to halt progression of myelopathy.Methods. The authors prospectively studied 20 adult patients with both Chiari I malformation and symptomatic syringomyelia. Testing before surgery included the following: clinical examination; evaluation of anatomy by using T1-weighted magnetic resonance (MR) imaging; evaluation of the syrinx and cerebrospinal fluid (CSF) velocity and flow by using phase-contrast cine MR imaging; and evaluation of lumbar and cervical subarachnoid pressure at rest, during the Valsalva maneuver, during jugular compression, and following removal of CSF (CSF compliance measurement). During surgery, cardiac-gated ultrasonography and pressure measurements were obtained from the intracranial, cervical subarachnoid, and lumbar intrathecal spaces and syrinx. Six months after surgery, clinical examinations, MR imaging studies, and CSF pressure recordings were repeated. Clinical examinations and MR imaging studies were repeated annually. For comparison, 18 healthy volunteers underwent T1-weighted MR imaging, cine MR imaging, and cervical and lumbar subarachnoid pressure testing.Compared with healthy volunteers, before surgery, the patients had decreased anteroposterior diameters of the ventral and dorsal CSF spaces at the foramen magnum. In patients, CSF velocity at the foramen magnum was increased, but CSF flow was reduced. Transmission of intracranial pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was partially obstructed. Spinal CSF compliance was reduced, whereas cervical subarachnoid pressure and pulse pressure were increased. Syrinx fluid flowed inferiorly during systole and superiorly during diastole on cine MR imaging. At surgery, the cerebellar tonsils abruptly descended during systole and ascended during diastole, and the upper pole of the syrinx contracted in a manner synchronous with tonsillar descent and with the peak systolic cervical subarachnoid pressure wave. Following surgery, the diameter of the CSF passages at the foramen magnum increased compared with preoperative values, and the maximum flow rate of CSF across the foramen magnum during systole increased. Transmission of pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was normal and cervical subarachnoid mean pressure and pulse pressure decreased to normal. The maximum syrinx diameter decreased on MR imaging in all patients. Cine MR imaging documented reduced velocity and flow of the syrinx fluid. Clinical symptoms and signs improved or remained stable in all patients, and the tonsils resumed a normal shape.Conclusions. The progression of syringomyelia associated with Chiari I malformation is produced by the action of the cerebellar tonsils, which partially occlude the subarachnoid space at the foramen magnum and act as a piston on the partially enclosed spinal subarachnoid space. This creates enlarged cervical subarachnoid pressure waves that compress the spinal cord from without, not from within, and propagate syrinx fluid caudally with each heartbeat, which leads to syrinx progression. The disappearance of the abnormal shape and position of the tonsils after simple decompressive extraarachnoidal surgery suggests that the Chiari I malformation of the cerebellar tonsils is acquired, not congenital. Surgery limited to suboccipital craniectomy, C-1 laminectomy, and duraplasty eliminates this mechanism and eliminates syringomyelia and its progression without the risk of more invasive procedures.

Advanced Chiari malformation Type I with marked spinal cord atrophy

Journal of Neurosurgery Spine ◽

10.3171/spi.2005.3.4.0324 ◽

2005 ◽

Vol 3 (4) ◽

pp. 324-327 ◽

Cited By ~ 2

Author(s):

Yoshiro Ito ◽

Koji Tsuboi ◽

Hiroyoshi Akutsu ◽

Satoshi Ihara ◽

Akira Matsumura

Keyword(s):

Spinal Cord ◽

Foramen Magnum ◽

Chiari I Malformation ◽

Type I ◽

Foramen Magnum Decompression ◽

Spinal Cord Atrophy ◽

Chiari Malformation Type I ◽

Content Type ◽

Neurological Improvement ◽

Chiari I

✓ The authors discuss the results obtained in patients who underwent foramen magnum decompression for longstanding advanced Chiari I malformation in which marked spinal cord atrophy was present. This 50-year-old woman presented with progressive quadriparesis and sensory disorders. Magnetic resonance imaging revealed the descent of cerebellar tonsils and medulla associated with remarkable C1—L2 spinal cord atrophy. After a C-1 laminectomy—based foramen magnum decompression, arachnoid dissection and duraplasty were undertaken. These procedures resulted in remarkable neurological improvement, even after 40 years of clinical progression. Spinal cord atrophy may be caused by chronic pressure of entrapped cerebrospinal fluid in the spinal canal.

Inclination of the odontoid process in the pediatric Chiari I malformation

Journal of Neurosurgery Spine ◽

10.3171/spi.2003.98.1.0043 ◽

2003 ◽

Vol 98 (1) ◽

pp. 43-49 ◽

Cited By ~ 15

Author(s):

R. Shane Tubbs ◽

John C. Wellons ◽

Jeffrey P. Blount ◽

Paul A. Grabb ◽

W. Jerry Oakes

Keyword(s):

Odontoid Process ◽

Postoperative Outcome ◽

Craniocervical Junction ◽

Foramen Magnum ◽

Chiari I Malformation ◽

Magnetic Resonance Images ◽

Posterior Aspect ◽

Content Type ◽

Chiari I ◽

Fine Print

Object. The quantitative analysis of odontoid process angulation has had scant attention in the Chiari I malformation population. In this study the authors sought to elucidate the correlation between posterior angulation of the odontoid process and patients with Chiari I malformation. Methods. Magnetic resonance images of the craniocervical junction obtained in 100 children with Chiari I malformation and in 50 children with normal intracranial anatomy (controls) were analyzed. Specific attention was focused on measuring the degree of angulation of the odontoid process and assigning a score to the various degrees. Postoperative outcome following posterior cranial fossa decompression was then correlated to grades of angulation. Other measurements included midsagittal lengths of the foramen magnum and basiocciput, the authors' institutions' previously documented pB—C2 line (a line drawn perpendicular to one drawn between the basion and the posterior aspect of the C-2 body), level of the obex from a midpoint of the McRae line, and the extent of tonsillar herniation. Higher grades of odontoid angulation (retroflexion) were found to be more frequently associated with syringomyelia and particularly holocord syringes. Higher grades of angulation were more common in female patients and were often found to have obices that were caudally displaced greater than three standard deviations below normal. Conclusions. These results not only confirm prior reports of an increased incidence of a retroflexed odontoid process in Chiari I malformation but quantitatively define grades of inclination. Grades of angulation were not found to correlate with postoperative outcome. It is the authors' hopes that these data add to our current limited understanding of the mechanisms involved in hindbrain herniation.

Quantitative description of the far-lateral transcondylar transtubercular approach to the foramen magnum and clivus

Journal of Neurosurgery ◽

10.3171/jns.2000.92.5.0824 ◽

2000 ◽

Vol 92 (5) ◽

pp. 824-831 ◽

Cited By ~ 89

Author(s):

Sergey Spektor ◽

Gregory J. Anderson ◽

Sean O. McMenomey ◽

Michael A. Horgan ◽

Jordi X. Kellogg ◽

...

Keyword(s):

Pathological Condition ◽

Quantitative Description ◽

Foramen Magnum ◽

Sigmoid Sinus ◽

Occipital Condyle ◽

Content Type ◽

Suboccipital Craniectomy ◽

Successive Step ◽

Far Lateral ◽

Fine Print

Object. The purpose of this study was to evaluate the far-lateral transcondylar transtubercular approach (complete FLA) based on quantitative measurements of the exposure of the foramen magnum and petroclival area obtained after each successive step of this approach.Methods. The complete FLA was reproduced in eight specially prepared cadaveric heads (a total of 15 sides). The approach was divided into six steps: 1) C-1 hemilaminectomy and suboccipital craniectomy with unroofing of the sigmoid sinus (basic FLA); 2) partial resection of the occipital condyle (up to the hypoglossal canal); 3) removal of the jugular tuberculum; 4) mastoidectomy (limited to the labyrinth and the fallopian canal) and retraction of the sigmoid sinus; 5) resection of the lateral mass of C-1 with mobilization of the vertebral artery; and 6) resection of the remaining portion of the occipital condyle. After each successive step, a standard set of measurements was obtained using a frameless stereotactic device. The measurements were used to estimate two parameters: the size of the exposed petroclival area and the size of a spatial cone directed toward the anterior rim of the foramen magnum, which depicts the amount of surgical freedom available for manipulation of instruments.The initial basic FLA provided exposure of only 21 ± 6% of the petroclival area that was exposed with the full, six-step maximally aggressive (complete) FLA. Likewise, only 18 ± 9% of the final surgical freedom was obtained after the basic FLA was performed. Each subsequent step of the approach increased both petroclival exposure and surgical freedom. The most dramatic increase in petroclival exposure was noted after removal of the jugular tuberculum (71 ± 12% of final exposure), whereas the least improvement in exposure occurred after the final step, which consisted of total condyle resection.Conclusions. The complete FLA provides wide and sufficient exposure of the foramen magnum and lower to middle clivus. The complete FLA consists of several steps, each of which contributes to increasing petroclival exposure and surgical freedom. However, the FLA may be limited to the less aggressive steps, while still achieving significant exposure and surgical freedom. The choice of complete or basic FLA thus depends on the underlying pathological condition and the degree of exposure required for effective surgical treatment.