Chiari I malformation accompanied by assimilation of the atlas, Klippel-Feil syndrome, and syringomyelia: case report

Revealing an Uncommon Presentation of Chiari I Malformation With Diverse Craniovertebral Anomalies in the Absence of Syringomyelia and Atlanto-Occipital Subluxation: A Case Report

A Chiari I malformation is a frequently encountered anomaly of the posterior fossa, occurring in a notable percentage of the population. It often coexists with various other craniovertebral junction abnormalities, albeit less frequently with Klippel-Feil syndrome. Interestingly, the majority of individuals with Chiari I malformation do not exhibit any symptoms. We present a rare case of a 25-year-old male with chronic neck and occipital pain, along with progressive weakness and sensory disturbances in all four limbs, urinary urgency, and elevated left shoulder. Examination unveiled spasticity, weakness, and brisk reflexes. On extensive radiological evaluation (X-ray, CT, and MRI), findings revealed various anomalies in the craniovertebral junction, including complete atlanto-occipital assimilation, basilar invagination, and platybasia. Furthermore, cervical segmentation abnormalities indicative of Klippel-Feil syndrome were observed, along with Sprengel's deformity. MRI confirmed Chiari I malformation with tonsillar herniation and myelomalacia, as well as compression at the cervico-medullary junction. This patient underwent a surgical procedure that included transoral odontoidectomy combined with occipito-cervical fixation, after which a good clinical response was observed. It emphasizes the necessity of radiological imaging for the diagnosis of Chiari and other associated abnormalities in the craniovertebral junction.

Human genetics and molecular genomics of Chiari malformation type 1

Chiari malformation type 1 (CM1) is the most common structural brain disorder involving the craniocervical junction, characterized by caudal displacement of the cerebellar tonsils below the foramen magnum into the spinal canal. Despite the heterogeneity of CM1, its poorly understood patho-etiology has led to a 'one-size-fits-all' surgical approach, with predictably high rates of morbidity and treatment failure. In this review we present multiplex CM1 families, associated Mendelian syndromes, and candidate genes from recent whole exome sequencing (WES) and other genetic studies that suggest a significant genetic contribution from inherited and de novo germline variants impacting transcription regulation, craniovertebral osteogenesis, and embryonic developmental signaling. We suggest that more extensive WES may identify clinically relevant, genetically defined CM1 subtypes distinguished by unique neuroradiographic and neurophysiological endophenotypes.

Transmandibular Cervical Corpectomy for Persistent Spinal Cord Compression in a Patient With Klippel-Feil Syndrome: A Technical Note and Systematic Review

BACKGROUND

Few studies have described a transmandibular approach for decompression in a patient with Klippel-Feil syndrome (KFS) for cervical myelopathy.

OBJECTIVE

To describe the transmandibular approach in a KFS patient with cervical myelopathy and to perform a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

METHODS

A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Embase and PubMed databases were searched from January 2002 to November 2022 for articles examining patients with KFS undergoing cervical decompression and/or fusion for cervical myelopathy and/or radiculopathy were included. Articles describing compression due to nonbony causes, lumbar/sacral surgery, nonhuman studies, or symptoms only from basilar invagination/impression were excluded. Data collected were sex, median age, Samartzis type, surgical approach, and postoperative complications.

RESULTS

A total of 27 studies were included, with 80 total patients. Thirty-three patients were female, and the median age ranged from 9 to 75 years. Forty-nine patients, 16 patients, and 13 patients were classified as Samartzis Types I, II, and III, respectively. Forty-five patients, 21 patients, and 6 patients underwent an anterior, posterior, and combined approach, respectively. Five postoperative complications were reported. One article reported a transmandibular approach for access to the cervical spine.

CONCLUSION

Patients with KFS are at risk of developing cervical myelopathy. Although KFS manifests heterogeneously and may be treated through a variety of approaches, some manifestations of KFS may preclude traditional approaches for decompression. Surgical exposure through the anterior mandible may prove an option for cervical decompression in patients with KFS.

Rare association of Klippel-Feil syndrome with situs inversus totalis and review of the genetic background

Klippel-Feil syndrome (KFS) is a rare congenital anomaly in forming the cervical vertebrae resulting in the fusion of two or more of the vertebrae. KFS is associated with many congenital anomalies, some of which are common and well known. Here, we report a child with an extremely rare association of KFS with situs inversus totalis (SIT). Both KFS and SIT are genetically heterogeneous and their co-occurrence suggests a high possibility of sharing the same underlying causative agent. Here, we review the genetic background that is known for these two conditions in the literature.

Chiari malformation and atlantoaxial instability: problems of co-existence

BACKGROUND

Association of Chiari malformation and atlantoaxial subluxation varies. There is a complex relationship between the two, bony and soft tissue pathologies.

METHODS

This is a review of various articles available from the literature on the management of Chiari and its association with atlantoaxial instability.

RESULTS

We have an experience of operating on 86 cases of paediatric atlantoaxial subluxation, of which 12 had Chiari malformation diagnosed preoperatively (13.95%). Of the 76 children with Chiari malformations operated on by us, 11 had associated atlantoaxial subluxation diagnosed on imaging (14.47%).

CONCLUSIONS

Re-alignment and reduction with fixation may be effective in achieving decompression in cases where reduction is possible from posterior approach. In these cases, posterior fixation is all that is required. If reduction is not possible from posterior and there is "fixed" ventral compression, anterior decompression needs to be combined with posterior fixation. In most cases, direct posterior decompression is warranted.

Chiari I malformation associated with atlanto-occipital assimilation presenting as orthopnea and cough syncope: a case report and review of literature

Although it is not uncommon for patients with Chiari I malformations to present with respiratory complaints, cough syncope is a rare presenting symptom. We report an adult patient who harbored both a Chiari I malformation and atlanto-occipital assimilation who complained of cough syncope, orthopnea, and central sleep apnea. The patient underwent decompressive craniectomy of the posterior fossa and cervical level 2 laminectomy. However, due to a possible initial underappreciation of the profound narrowing of the foramen magnum as a result of these concomitant pathologies, the patient may have had continued impaired cerebrospinal fluid flow, leading to a symptomatic pseudomeningocele and requiring a more extensive decompression that included a cervical level 3 laminectomy as well as a temporary lumbar drain. On 2-year follow-up, he has remained asymptomatic.

Stratified whole genome linkage analysis of Chiari type I malformation implicates known Klippel-Feil syndrome genes as putative disease candidates

Chiari Type I Malformation (CMI) is characterized by displacement of the cerebellar tonsils below the base of the skull, resulting in significant neurologic morbidity. Although multiple lines of evidence support a genetic contribution to disease, no genes have been identified. We therefore conducted the largest whole genome linkage screen to date using 367 individuals from 66 families with at least two individuals presenting with nonsyndromic CMI with or without syringomyelia. Initial findings across all 66 families showed minimal evidence for linkage due to suspected genetic heterogeneity. In order to improve power to localize susceptibility genes, stratified linkage analyses were performed using clinical criteria to differentiate families based on etiologic factors. Families were stratified on the presence or absence of clinical features associated with connective tissue disorders (CTDs) since CMI and CTDs frequently co-occur and it has been proposed that CMI patients with CTDs represent a distinct class of patients with a different underlying disease mechanism. Stratified linkage analyses resulted in a marked increase in evidence of linkage to multiple genomic regions consistent with reduced genetic heterogeneity. Of particular interest were two regions (Chr8, Max LOD = 3.04; Chr12, Max LOD = 2.09) identified within the subset of "CTD-negative" families, both of which harbor growth differentiation factors (GDF6, GDF3) implicated in the development of Klippel-Feil syndrome (KFS). Interestingly, roughly 3-5% of CMI patients are diagnosed with KFS. In order to investigate the possibility that CMI and KFS are allelic, GDF3 and GDF6 were sequenced leading to the identification of a previously known KFS missense mutation and potential regulatory variants in GDF6. This study has demonstrated the value of reducing genetic heterogeneity by clinical stratification implicating several convincing biological candidates and further supporting the hypothesis that multiple, distinct mechanisms are responsible for CMI.

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.

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

OBJECT

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Klippel-Feil syndrome associated with situs inversus: description of a new case and exclusion of GDF1, GDF3 and GDF6 as causal genes

OBJECTIVE

Klippel-Feil syndrome is characterized by faulty segmentation of two or more cervical vertebrae and, in its most severe form, consists of massive cervical vertebral fusion, short neck, low posterior hairline, and limitation of head movement. Several cases associating Klippel-Feil syndrome with situs inversus totalis have been reported. In the present study, we describe the clinical features of a novel case of Klippel-Feil syndrome associated with situs inversus totalis and searched for mutations in GDF1, GDF3 and GDF6 genes, which were recently implicated in the development of skeletal and visceral anomalies.

METHODS

A case of Klippel-Feil syndrome associated with situs inversus totalis underwent a full clinical examination including X-ray of cervical spine and thorax, abdominal ultrasound, and computerized tomography scanning of thorax and abdomen. PCR amplification and automated nucleotide sequencing of coding exons and intron-exon junctions of GDF1, GDF3, and GDF6 genes were performed in genomic DNA.

RESULTS

No molecular alterations were found in GDF1, GDF3 and GDF6 genes in this patient.

CONCLUSION

An additional patient associating Klippel-Feil syndrome and situs inversus totalis is reported. Mutations in GDF1, GDF3, and GDF6 genes were excluded as the cause of this unusual clinical association.

Chiari malformation type I: related conditions

Chiari malformation type I (CMI) is a morphological diagnosis defined as the inferior displacement of the cerebellum through the foramen magnum. In parallel to this basic definition of CMI, there are diagnoses that co-exist with CMI in selected patients. In addition, there are specific constellations of clinical symptoms and signs reported in the literature that occur non-randomly in patients affected by CMI. There is no established system that categorizes these CMI-related conditions or even defines them as causes or consequences of CMI. Identifying the relationship between CMI and these associated disorders may allow greater understanding of CMI etiology and potentially inform CMI management.

Specific entities affecting the craniocervical region: syndromes affecting the craniocervical junction

INTRODUCTION

The craniocervical junction is a vital component in understanding the function of the human central nervous system. It is the threshold for major pathways affecting both brain and spinal cord function, and these structures are intricately housed in a network of bone, ligaments, and soft tissues. Abnormal development of any of these components may lead to altered structure, and therefore, altered function in the central nervous system.

MATERIALS AND METHODS

We herein describe a set of genetic syndromes that commonly affect the craniovertebral junction and offer clinical examples from more than 6,000 patients who have been treated for these disorders.

DISCUSSION

The syndromes described include Chiari type I malformation, Conradi syndrome, Goldenhar syndrome, Klippel-Feil syndrome, Larsen syndrome, Morquio syndrome, Pierre-Robin syndrome, spondyloepiphyseal dysplasia congenital and Weaver syndrome. The genetic mechanisms responsible for these disorders may offer unique insight into the developmental pathways and patterning in the musculoskeletal and cranial systems and may, ultimately, guide future diagnosis and treatment.

Craniocervical junction fusions in patients with hindbrain herniation and syringohydromyelia

OBJECT

Patients with hindbrain herniation or the so-called Chiari malformation Type I (CM-I) and/or syringohydromyelia are treated with dorsal decompression alone; however, a small percentage of patients with other associated abnormalities require concomitant dorsal craniocervical junction (CCJ) fusion. The authors surveyed the indications for CCJ fusions in this population.

METHODS

A retrospective review of University of Iowa medical records and radiographs obtained between 1996 and 2005 was performed. Inclusion criteria encompassed patients with diagnoses of CM-I and/or syringohydromyelia requiring dorsal CCJ fusions, and others with CCJ abnormalities who had CM-I and/or syringohydromyelia.

RESULTS

Two hundred thirty-four patients were identified, all of whom were symptomatic at presentation. Their ages ranged from 2.5 to 86 years; 33% of the patients were < 16 years of age. Patients were categorized as follows, with some being assigned to > 1 category: Group I, congenital or acquired CCJ abnormalities with reducible bone compression (25% of patients); Group II, previous anterior CCJ/upper brainstem decompression (44%); Group III, occipitocervical complex instability with CM-I and/or syringohydromyelia but without CCJ bone abnormalities requiring adjunctive posterior fossa decompression (26%); and Group IV, musculoligamentous instability, either from pathological states or from muscle dehiscence from repeated posterior fossa procedures (14%). Instrumentation was used in 96% of patients, with all 96% receiving semirigid fixation with titanium loop and sublaminar cables; all fusion constructs incorporated autologous bone. At last follow-up evaluation, fusion was radiographically complete in 97%, and symptom improvement was seen in 92%.

CONCLUSIONS

Dorsal CCJ fusions are required in patients with CM-I and/or syringohydromyelia who have concomitant CCJ abnormalities (Groups I and II). A definite group (CM-I and/or syringohydromyelia) without bone abnormality exists (Groups III and IV). This may be due to muscle weakness secondary to a high syrinx.

Surgical management of Chiari malformation: analysis of 128 cases

OBJECTIVE

A variety of surgical interventions have been recommended for patients with Chiari malformations (CMs). In this study, we have evaluated the intraoperative findings and clinical outcome in different-aged patients with CMs undergoing posterior fossa decompression.

METHODS

Sixteen pediatric and 112 adult cases with CMs underwent suboccipital craniectomy and wide duraplasty as well as autogenous bone grafting in selected cases. The clinical outcome was assessed by evaluation of postoperative signs and symptoms and magnetic resonance imaging of the craniocervical junction.

RESULTS

The most striking intraoperative finding was the presence of a very thin membrane over the opening of the central canal; the occurrence of this membrane in pediatric patients was significantly higher than that in adults (94 and 43%, respectively; p < 0.05, Fisher's exact probability test). During the immediate postoperative period, 81% of pediatric CMs and 90% of adult CMs showed improved symptomatology and magnetic resonance imaging revealed favorable findings comprising syrinx collapse or reduction of the syrinx diameter in 14 (88%) pediatric and 92 (82%) adult CMs. During discharge from hospital, 103 (90%) patients with CMs type I and 11 (85%) with CMs type II achieved good results. However, there was a statistically significant difference in the occurrence of poor results between patients treated with bony fusion and those without fusion (24 vs. 6%;p < 0.05, Fisher's exact probability test). The incidence of vertebral instability was markedly augmented in pediatric CMs in comparison to adult CMs (19 vs. 2%; p < 0.01, Fisher's exact probability test).

CONCLUSIONS

Suboccipital decompression and duraplasty with autogenous bone grafts in selected cases are effective treatments for most patients with CMs. A higher incidence of a special membrane over the obex and atlantoaxial instability were closely associated with childhood CMs.