-
Operative Neurosurgery (Hagerstown, Md.) Apr 2024Patients with basilar invagination (BI) can be treated with several surgical options, ranging from simple posterior decompression to circumferential decompression and...
BACKGROUND AND OBJECTIVES
Patients with basilar invagination (BI) can be treated with several surgical options, ranging from simple posterior decompression to circumferential decompression and fusion. Here, we aimed at examining the indications and outcomes associated with these surgical strategies to devise a staged algorithm for managing BI.
METHODS
We conducted a retrospective cohort study in 2 neurosurgical centers and included patients with a BI, as defined by a position of the dens tip at least 5 mm above the Chamberlain line. Other craniovertebral junction anomalies, such as atlas assimilation, platybasia, and Chiari malformations, were documented. C1-C2 stability was assessed with a dynamic computed tomography scan.
RESULTS
We included 30 patients with BI with a mean follow-up of 56 months (min = 12, max = 166). Posterior decompression and fusion (n = 8) was only performed in cases of obvious atlanto-axial instability (eg, increased atlanto-dental interval or hypermobility on flexion/extension), while anterior decompression (transoral or transnasal) was reserved to patients with lower cranial nerves deficits (eg, swallowing dysfunction) and irreducible anterior compression (n = 9). Patients with posterior signs (eg, Valsalva headaches) or myelopathy but without C1-C2 instability nor anterior signs were managed with an isolated foramen magnum decompression, with or without duraplasty (n = 13). Complications were more frequent for combined procedures, including neurological deterioriation (n = 4) and tracheostomy (n = 2), but reinterventions were more likely in patients undergoing posterior decompression alone (n = 3).
CONCLUSION
Patient selection is key to determine the appropriate surgical strategy for BI: In our experience, combined approaches are only needed for patients with irreducible and symptomatic anterior compression, while fusion should be restricted to patient with obvious signs of atlanto-axial instability. Other BI patients can be managed by foramen magnum decompression alone to minimize surgical morbidity.
PubMed: 38869484
DOI: 10.1227/ons.0000000000001152 -
Acta Neurochirurgica Oct 2022Treatments for symptomatic or unstable basilar invagination (BI) include posterior decompression, distraction/fusion, trans-nasal or trans-oral anterior decompression,...
BACKGROUND
Treatments for symptomatic or unstable basilar invagination (BI) include posterior decompression, distraction/fusion, trans-nasal or trans-oral anterior decompression, and combined techniques, with the need for occipitocervical fusion based on the degree of craniocervical instability. Variations of the far lateral transcondylar approach are described in limited case series for BI, but have not been widely applied.
METHODS
A single-institution, retrospective review of consecutive patients undergoing a far lateral transcondylar approach for odontoidectomy (± resection of the inferior clivus) followed by occipitocervical fusion over a 6-year period (1/1/2016 to 12/31/2021) is performed. Detailed technical notes are combined with images from cadaveric dissections and patient surgeries to illustrate our technique using a lateral retroauricular incision.
RESULTS
Nine patients were identified (3 males, 6 females; mean age 40.2 ± 19.6 years). All patients had congenital or acquired BI causing neurologic deficits. There were no major neurologic or wound-healing complications. 9/9 patients (100%) experienced improvement in preoperative symptoms.
CONCLUSIONS
The far lateral transcondylar approach provides a direct corridor for ventral brainstem decompression in patients with symptomatic BI. A comprehensive knowledge of craniovertebral junction anatomy is critical to the safe performance of this surgery, especially when using a lateral retroauricular incision.
Topics: Adult; Decompression, Surgical; Female; Humans; Male; Middle Aged; Nose; Platybasia; Retrospective Studies; Spinal Fusion; Young Adult
PubMed: 35867183
DOI: 10.1007/s00701-022-05312-9 -
Journal of Clinical Orthopaedics and... Feb 2021A Prospective Study.
STUDY DESIGN
A Prospective Study.
OBJECTIVE
To assess results of posterior occipito-cervical decompression and fusion operated with intra-operative traction/manipulation and instrumented reduction in cases of Basilar Invagination(BI).
METHODS
Total 22 patients of 8-65 years with diagnosed BI were operated for posterior occipito-cervical fusion by intra-operative traction/manipulation and instrumented reduction. Fusion was done using autologous bone graft taken from iliac crest. Immediate post-operative, first month and then every 3 months' follow-up examination were done for minimum period of 2 years.
RESULTS
22 patients (10 males,12 females) with mean age of 23.9 years having BI were included. 11 patients had C1 occipitalization, 4 had platybasia and 9 had atlanto-axial dislocation (AAD). 1 patient with os odontoideum with kyphotic deformity expired on 4th postoperative day due to respiratory insufficiency (mortality rate 4.54%). Neurological improvement by at least by one grade according to RANAWAT's and/or NURICK'S scale was observed in 17/21 patients (80.95%). 3 patients remained static and 1 had neuro-worsening. Mean mJOA score of 13.14 improved to 16.24. All had reduction of dens below foramen magnum according to McRae, chamberlain line and Ranawat index. Bone graft fused in all patients as confirmed with CT scan and dynamic X-rays. 1 wound dehiscence and 1 asymptomatic implant loosening were seen on follow-up.
CONCLUSION
Surgical treatment of BI with intra-operative traction/manipulation, instrumented reduction and posterior occipito-cervical fusion can achieve good correction of radiology, functional performance and clinical neurology as well as excellent fusion rates without adverse effects of trans-oral surgery.
PubMed: 33680811
DOI: 10.1016/j.jcot.2020.11.016 -
World Neurosurgery Jun 2022C1/2 facet configurations and clivus-canal-angles (CXAs) have been proposed as criteria for posterior fusion in Chiari I malformation (CMI).
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.
Topics: Adult; Arnold-Chiari Malformation; Cranial Fossa, Posterior; Decompression, Surgical; Foramen Magnum; Humans; Magnetic Resonance Imaging; Platybasia
PubMed: 35247617
DOI: 10.1016/j.wneu.2022.02.110 -
European Journal of Medical Genetics Aug 2020Primrose syndrome (OMIM 259050) is a rare disorder characterised by macrocephaly with developmental delay, a recognisable facial phenotype, altered glucose metabolism,...
Primrose syndrome (OMIM 259050) is a rare disorder characterised by macrocephaly with developmental delay, a recognisable facial phenotype, altered glucose metabolism, and other features such as sensorineural hearing loss, short stature, and calcification of the ear cartilage. It is caused by heterozygous variants in ZBTB20, a member of the POK family of transcription repressors. Recently, this gene was shown to have a role in skeletal development through its action on chondrocyte differentiation by repression of SOX9. We describe five unrelated patients with Primrose syndrome and distinct skeletal features including multiple Wormian bones, platybasia, bitemporal bossing, bathrocephaly, slender bones, epiphyseal and spondylar dysplasia. The radiological abnormalities of the skull and the epiphyseal dysplasia were the most consistent findings. This novel constellation of skeletal features expands the phenotypic spectrum of the disorder.
Topics: Abnormalities, Multiple; Adolescent; Bone and Bones; Calcinosis; Child; Child, Preschool; Ear Diseases; Female; Humans; Intellectual Disability; Male; Muscular Atrophy; Nerve Tissue Proteins; Phenotype; SOXB1 Transcription Factors; Transcription Factors; Young Adult
PubMed: 32473227
DOI: 10.1016/j.ejmg.2020.103967 -
Neurological Sciences : Official... Jul 2020The craniovertebral junction is an anatomically well-defined transitional zone located between the skull and the cervical spine. Multiple malformations can affect this...
BACKGROUND
The craniovertebral junction is an anatomically well-defined transitional zone located between the skull and the cervical spine. Multiple malformations can affect this region with the most prominent being basilar invagination (BI) and Chiari malformation (CM). Despite numerous studies, the origin, pathophysiology, and classification of these pathologies remain controversial. The objective of this study was to evaluate the implication of cranial base flexion angle and clivus length in the development of these conditions.
METHODS
Midline tomography and magnetic resonance imaging of normal subjects and patients diagnosed with BI (types I and II) and Chiari malformation were evaluated. A craniometric study of the skull base was performed. Linear and angular measurements were used for comparisons between groups.
RESULTS
109 images from patients with craniovertebral junction malformation and controls were evaluated. Seventeen had BI-I, 26 had BI-II, 36 had CM, and 30 were normal subjects. Demographic data for the two groups were not significantly different. Craniometric analysis of images revealed a gradation in linear and angular variables from controls to CM, BI-I, and BI-II patients. Clivus length was significantly smaller in BI-II patients compared with other groups, while basal angle was greater. Moderate or strong correlations were noted among all variables analyzed.
CONCLUSION
Data suggest that clivus length and basal angle may play a role in pathophysiology of BI and CM.
Topics: Arnold-Chiari Malformation; Cephalometry; Cranial Fossa, Posterior; Humans; Magnetic Resonance Imaging; Platybasia; Skull Base
PubMed: 32002740
DOI: 10.1007/s10072-020-04248-1 -
Zhonghua Yi Xue Za Zhi Nov 2022Regarding the treatment of type A basilar invagination, there is a debate between the combination of anterior and posterior surgery and posterior fixation. The author's...
Regarding the treatment of type A basilar invagination, there is a debate between the combination of anterior and posterior surgery and posterior fixation. The author's personal opinion on the hot topic of cranial vertebral surgery: the surgical plan of type A basilar invagination is expressed in this article. Overall, the combined anterior-posterior approach is applicable in almost all cases of type A basilar invagination, regardless of how severe atlantoaxial dislocation, and simple posterior surgery is only in cases where atlantoaxial dislocation is not very severe. The anterior-posterior combined surgery has two incisions, and the risk of postoperative infection is higher than for posterior surgery alone. If the patient has no spinal cord symptoms, only posterior surgery is acceptable, even if no anatomical reduction can be achieved. If there is a more severe spinal cord dysfunction, or a large syringomyelia, anterior atlantoaxial release is necessary to ensure achieving anatomical reduction and restoring the normal morphology of the cervical spinal cord.
Topics: Humans; Atlanto-Axial Joint; Platybasia; Joint Dislocations; Spine; Spinal Fusion
PubMed: 36396355
DOI: 10.3760/cma.j.cn112137-20220418-00836 -
British Journal of Neurosurgery Dec 2023Sleep apnoea is common in patients with Basilar Invagination with Arnorld Chiari Malformation (ACM). Various studies have shown its incidence in the range of 60-70%... (Review)
Review
Sleep apnoea is common in patients with Basilar Invagination with Arnorld Chiari Malformation (ACM). Various studies have shown its incidence in the range of 60-70% among such patients. Most of the studies have shown improvement in sleep disturbances after decompressive surgeries for Chiari Malformations. There is no report of postoperative deterioration due to sleep apnoea in these patients. Authors report two cases of basilar invagination associated with ACM and Platybasia, who deteriorated probably due to worsening of pre-existing sleep disorders on 3rd and 7th postoperative days after their surgeries, despite clinico-radiological improvements during their early post-operative courses. Authors discuss literature related to sleep apnoea in basilar invagination associated with Chiari Malformations and share precautions, which are relevant and should be undertaken in such patients especially during early post-operative periods to avoid alarming complication which may occur even in experienced hands.
Topics: Humans; Platybasia; Arnold-Chiari Malformation; Sleep Apnea Syndromes; Decompression, Surgical; Sleep
PubMed: 34251945
DOI: 10.1080/02688697.2021.1947981 -
Spine Jun 2024Retrospective study.
STUDY DESIGN
Retrospective study.
OBJECTIVE
To evaluate the feasibility of C2 pedicle screw fixation with the "in-out-in" technique in patients with basilar invagination (BI).
SUMMARY OF BACKGROUND DATA
The "in-out-in" technique is a fixation technique in which the screw enters the vertebrae through the parapedicle. The technique has been used in upper cervical spine fixation. However, anatomic parameters associated with the application of this technique in patients with BI are unclear.
MATERIALS AND METHODS
We measured the C2 pedicle width (PW), the distance between the vertebral artery (VA) and the transverse foramen (VATF), the safe zone, and the limit zone. The lateral safe zone is the distance from the medial/lateral cortex of the C2 pedicle to the VA (LPVA/MPVA), and the medial safe zone is the distance from the medial/lateral cortex of the C2 pedicle to the dura (MPD/LPD). The lateral limit zone is the sum of LPVA/MPVA and VATF (LPTF/MPTF), and the medial limit zone is the distance from the medial/lateral cortex of the C2 pedicle to the spinal cord (MPSC/LPSC). PW, LPVA, MPVA, and VATF were measured on the reconstructed CT angiography. PW, MPD, LPD, MPSC, and LPSC were measured on MRI. We define a width greater than 4 mm as safe for screw. The t -test was used to compare the parameters between male and female, left and right sides in all patients, and PW in CTA and MRI data in the same patient. For intrarater reliabilities, interclass correlation coefficients were calculated.
RESULTS
A total of 154 patients (49 CTA, 143 MRI) were included. The average PW, LPVA, MPVA, LPTF, MPTF, MPD, LPD, MPSC, and LPSC were 5.30 mm, 1.28 mm, 6.60 mm, 2.45 mm, 8.94 mm, 2.09 mm, 7.07 mm, 5.51 mm, and 10.48 mm, respectively. Furthermore, in patients with PW <4 mm, 53.6% of MPVA, 86.2% of LPTF, and all limit zones were larger than 4 mm.
CONCLUSIONS
In patients with BI, there is sufficient space medially and laterally to the C2 pedicle for partial screw encroachment to achieve "in-out-in" fixation, even if the pedicle is small.
LEVEL OF EVIDENCE
Level-4.
Topics: Humans; Male; Pedicle Screws; Female; Feasibility Studies; Retrospective Studies; Adult; Middle Aged; Cervical Vertebrae; Spinal Fusion; Aged; Platybasia; Young Adult; Treatment Outcome; Vertebral Artery
PubMed: 37339267
DOI: 10.1097/BRS.0000000000004757 -
BMC Neurology May 2020We propose two new concepts, the Filum Disease (FD) and the Neuro-cranio-vertebral syndrome (NCVS), that group together conditions thus far considered idiopathic, such...
BACKGROUND
We propose two new concepts, the Filum Disease (FD) and the Neuro-cranio-vertebral syndrome (NCVS), that group together conditions thus far considered idiopathic, such as Arnold-Chiari Syndrome Type I (ACSI), Idiopathic Syringomyelia (ISM), Idiopathic Scoliosis (IS), Basilar Impression (BI), Platybasia (PTB) Retroflexed Odontoid (RO) and Brainstem Kinking (BSK).
METHOD
We describe the symptomatology, the clinical course and the neurological signs of the new nosological entities as well as the changes visible on imaging studies in a series of 373 patients.
RESULTS
Our series included 72% women with a mean age of 33.66 years; 48% of the patients had an interval from onset to diagnosis longer than 10 years and 64% had a progressive clinical course. The commonest symptoms were: headache 84%, lumbosacral pain 72%, cervical pain 72%, balance alteration 72% and paresthesias 70%. The commonest neurological signs were: altered deep tendon reflexes in upper extremities 86%, altered deep tendon reflexes in lower extremities 82%, altered plantar reflexes 73%, decreased grip strength 70%, altered sensibility to temperature 69%, altered abdominal reflexes 68%, positive Mingazzini's test 66%, altered sensibility to touch 65% and deviation of the uvula and/or tongue 64%. The imaging features most often seen were: altered position of cerebellar tonsils 93%, low-lying Conus medullaris below the T12L1 disc 88%, idiopathic scoliosis 76%, multiple disc disease 72% and syringomyelic cavities 52%.
CONCLUSIONS
This is a paradigm shift that opens up new paths for research and broadens the range of therapeutics available to these patients.
Topics: Adolescent; Adult; Aged; Arnold-Chiari Malformation; Brain Stem; Child; Child, Preschool; Female; Headache; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Platybasia; Scoliosis; Syringomyelia; Young Adult
PubMed: 32393196
DOI: 10.1186/s12883-020-01743-y