Posterior Occipitocervical Fixation and Intrathecal Baclofen Therapy for the Treatment of Basilar Invagination with Klippel-Feil Syndrome: A Case Report.

Klippel-Feil syndrome (KFS) is characterized by the congenital fusion of the cervical vertebrae and is sometimes accompanied by anomalies in the craniocervical junction. In basilar invagination (BI), which is a dislocation of the dens in an upper direction, compression of the brainstem and cervical cord results in neurological defects and surgery is required. A 16-year-old boy diagnosed with KFS and severe BI presented with spastic tetraplegia, opisthotonus and dyspnea. CT scans showed basilar impression, occipitalization of C1 and fusion of C2/C3. MRI showed ventral compression of the medullocervical junction. Posterior occipitocervical reduction and fusion along with decompression were performed. Paralysis gradually improved postoperatively over 3 weeks. However, severe spasticity and opisthotonus persisted and intrathecal baclofen (ITB) therapy was initiated. Following this, opisthotonus disappeared and spasticity of the extremities improved. Rehabilitation therapy continued by controlling the dose of ITB. Five years after the surgery, self-propelled wheelchair driving was achieved and activities of daily life improved. The treatment strategy for patients with BI and congenital anomalies remains controversial. Posterior reduction and internal fixation using instrumentation were effective techniques in this case. Spasticity control achieved through a combination of surgery and ITB treatment enabled the amelioration of therapeutic efficacy of rehabilitation and the improvement of ADL.

Morphology of the Occipital Bones and Foramen Magnum Resulting From Premature Minor Suture Fusion in Crouzon Syndrome.

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion.Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis.Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest's Craniofacial Imaging Database (WFCID).Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery.None.2D and 3D cephalometric measurements.3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (ß = -398.75; P < .05) and petrous-occipital (ß = -727.5; P < .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (ß = -14 723.1; P < .001) and occipitomastoid synchondrosis (ß = -16 419.3; P < .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (ß = -673.3; P < .001), anterior intraoccipital synchondrosis (ß = -368.47; P < .05), and posterior intraoccipital synchondrosis (ß = -6261.42; P < .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion.Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.

Association Between the Clivus Slope and Patient-Reported Japanese Orthopaedic Association (PRO-JOA) Scores in Patients with Basilar Invagination: A Retrospective Study.

AIM: To determine a quantitative relationship between the postoperative clivus slope (CS) and the change in the Patient-Reported Japanese Orthopaedic Association (PRO-JOA) scores following reduction surgery of the basilar invagination (BI). MATERIAL AND METHODS: A single center retrospective study was conducted. Patients who met the inclusion and exclusion criteria at our hospital during the period from August 2015 to August 2020 were identified. The CS was introduced. Radiographic parameters including the CS were measured to assess realignment preoperatively and postoperatively. The PRO-JOA score was recorded to reveal the clinical outcome. The PRO-JOA score and the radiographic parameters that included the CS were compared between postoperative BI patients. RESULTS: Ninety-four patients with BI were included in the study. The CS (0.96, 0.93-1.00) was inversely correlated with the PROJOA score. The CS was negatively associated with the ΔPRO-JOA score in the crude model, while no significant associations in the fully adjusted model, although in the case of the latter, a slight trend was found (p for trend < < 0.05). In the non-linear model, the CS was negatively associated with the ΔPRO-JOA score in patients diagnosed with BI, unless the CS exceeded 63.4°. CONCLUSION: A reduction in the CS affects the postoperative PRO-JOA score of BI patients. This relationship can be employed as a quantitative reference in determining preoperative design with respect to the intraoperative correction needed to reduce craniovertebral junction deformity in BI.

Congenital Fusion of Dens to T3 Vertebra in Klippel-Feil Syndrome.

BACKGROUND: Patients with Klippel-Feil syndrome may present with neurologic complaints such as neck pain, radiculopathy and gait instability. Here we describe surgical management of a patient with congenital fusion of the occipital-cervical region and also block circumferential fusion of dens to T3 with spinal cord compression. This report is the first of its kind with such extensive fusion. CASE DESCRIPTION: Our patient was a 56 year-old female, who presented with neck pain and tingling in all extremities. On exam, she had a short neck, prominent jaw with extremely limited range of motion in neck and features of myelopathy. CT showed fusion of the dens to T3 vertebrae. Patient underwent sub-occipital craniectomy, C1 laminectomy and Occiput to T5 posterior fixation and fusion with neurologic improvement. CONCLUSION: This is the first reported case of Klippel-Feil syndrome with fusion of all cervical vertebrae down to T3. We recommend surgery for advanced cases of myelopathy or radiculopathy due to stenosis and spinal instability.

Occipital Encephalocele: Cause, Incidence, Neuroimaging and Surgical Management.

AIMS: To review and present the current knowledge of incidence, signs and symptoms, diagnosis and treatment of the occipital encephalocele. BACKGROUND: Encephalocele (E) is a defect of the neural tube that refers to congenital malformations featured by skull defect and dura with extracranial spread of intracranial structures. Occipital encephalocele (OE) are the most common form of this congenital disorder and are manifested as a swelling of different sizes over the occipital bone in the midline. Proper diagnosis and treatment is highly important in the management of this congenital malformation of brain. OBJECTIVE: To review and present the current knowledge of incidence, signs and symptoms, diagnosis and treatment of the occipital encephalocele. METHODS: We conducted a search of case reports or case-series of patients by the use of electronic databases: Pub Med, Medline, Index Medicus, Scorpus. The key words were: encephalocele, occipital encephalocele, neural tube defect, congenital malformation. The search was updated to December 31, 2018. Papers published in English were the only source of information. RESULTS: Occipital encephalocelle are more frequent in females than in males. The incidence is between 1 in 3000 to 1 in 10,000 live births; approximately 90% of them involve the midline. Magnetic resonance imaging is the method of choice in diagnosis and surgery is the best option for the treatment of OE. Overall morbidity and mortality is still high in spite of advenced surgical management, but have been significantly improved in recent years thanks to sophisticated highresolution imaging, adequate and proper surgical treatment and decent post-operative care. CONCLUSION: Occipital encephalocele is the most common form of encephalocele. The diagnosis is mostly based by the use of neuroimaging techniques. Operation is the best option for treatment. Overall morbidity and mortality is still high, but have been significantly improved in recent years thanks to sophisticated high-resolution imaging, adequate and proper surgical treatment and decent post-operative care.

[Reduction of the atlantoaxial dislocation associated with basilar invagination through single-stage posterior approach: using Xuanwu occipital-cervical reduction surgical suite].

Objective: To examine the effect of posterior reduction in atlantoaxial dislocation (AAD) associated with basilar invagination(BI) using Xuanwu occipital-cervical fusion system in single stage. Methods: Thirty-seven AAD accompanied with BI cases treated at Department of Neurosurgery, Xuanwu Hospital, Capital Medical Universiy and the Second Hospital of Hebei Medical University were retrospective analyzed. There were 15 males and 22 females with age of (42.3±12.3)years (range: 18-69 yars). All the cases had congenital osseous abnormalities, such as assimilation of atlas and abnormal cervical fusion. Anterior tissue was released through posterior route followed by cage implantation into facet joint and occipital-cervical fixation with cantilever technique. The clinical results were evaluated using Japanese Orthopedic Association scale(JOA) and the main radiological measurements including anterior atlantodental interval (ADI),the distance of odontoid tip above Chamberlain line,clivus-canal angle (CCA) and the length of syrinx were collected.The preoperative and postoperative JOA score and radiological measurements were compared by paired t-test. Results: The mean JOA score of the patients increased from 10.5 to 14.4 at the one-year follow-up(t=14.3,P=0.00).Complete reduction of AAD and BI was achieved in 34 patients.The mean clivus-canal angle improved from 118.0 degrees preoperative to 143.7 degrees postoperative(t=6.2,P=0.00). Shrinkage of the syrinx was observed 1 week after surgery in 24 patients, and 6 months in 31 patients. Twenty-eight patients achieved bone fusion 6 months after surgery. All the patients achieved bone fusion 12 months after surgery. One-side vertebral artery occlusion was diagnosed in 1 case postoperatively for transient dizziness, and relieved in 2 weeks. Two patients developed moderate neck pain after surgery, and relieved in 1 month. No implant failure, spacer subsidence or infection was observed. Conclusions: The treatment of AAD associated with BI using Xuanwu occipital-cervical fusion system from posterior approach in single stage is effective and safe. Cage implantation intraarticularly and fixation with cantilever technique achieve complete reduction in most cases.

Sagittal suture craniosynostosis or craniosynostoses? The heterogeneity of the most common premature fusion of the cranial sutures.

BACKGROUND: Scaphocephaly is usually defined as the deformation of the skull resulting from the premature fusion of the sagittal suture. It is the most common type of craniosynostosis, and can be easily recognized on simple clinical examination. Its pathophysiology is easy to understand and to confirm on neuroradiological examination. In contrast, surgical indications are still somewhat controversial, the dispute mainly concerning therapeutic versus esthetic objectives. In recent years, however, several studies have challenged these basic and relatively simplistic interpretations of the pathophysiology of the condition. MATERIALS AND METHODS: To assess the heterogeneity of scaphocephaly, we reviewed cases of scaphocephaly operated on at the Hôpital Femme-Mère-Enfant, Lyon University Hospital, France during a 10-year period (2008-2017) and performed a review of the literature on scaphocephaly and sagittal suture closure. RESULTS: During the 10-year period, 401 children were operated on for a scaphocephaly at the Hôpital Femme Mère Enfant, Lyon University Hospital. Mean age at surgery was 1.14 years, for a median 0.7 years (range, 4 months to 8. 5 years). Several subtypes could be distinguished according to morphology, intracranial findings on imaging, patient age, and etiology associated to the sagittal synostosis. Two main surgical techniques were used to correct the malformation, depending on patient age, type of deformation and the surgeon's preference: cranial vault remodeling with occipital pole widening, with the patient in a prone position, and parietal enlargement with or without forehead remodeling, in dorsal decubitus. CONCLUSIONS: The complexity and heterogeneous nature of sagittal synostoses depend on different pathogenic mechanisms leading to and interfering with the skull abnormalities: abnormalities of CSF dynamics, possibly associated with systemic alterations, accounting for the varied postoperative morphological and functional course, in terms of cognitive impairment and late complications (notably intra-cranial pressure elevation). However, the real impact of such heterogeneous clinical presentations on surgical indications and surgical results remains to be elucidated.

Torticollis Caused by Nontraumatic Craniovertebral Junction Abnormalities.

Torticollis could be the only symptom and sign of craniovertebral junction (CVJ) abnormality. It could be difficult to identify CVJ abnormality as a cause of torticollis due to their rarity, especially for the subjects with torticollis caused by nontraumatic CVJ abnormalities. There has been no report to focus on nontraumatic CVJ abnormalities as a cause of torticollis. The objective of this study was to report 27 patients of torticollis caused by nontraumatic CVJ abnormalities, with the aim of helping clinicians to identify nontraumatic CVJ abnormalities as a cause of torticollis. This is a retrospective cohort study including 27 subjects who had torticollis caused by nontraumatic CVJ abnormalities. The CVJ was examined in terms of atlanto-occipital angle, atlanto-axial angle, and lateral and anterior atlanto-dens intervals for the evaluation of occipital condylar hypoplasia, rotation of atlanto-axial joint, and lateral and anterior shift of the dens, respectively. Abnormalities of the lower cervical or thoracic spine were also evaluated. Occipital condylar hypoplasia, rotation of atlanto-axial joint, and lateral shift of the dens were the most common CVJ abnormalities. The 18.5% of the subjects had concurrent anomalies of lower cervical or thoracic vertebrae along with CVJ abnormalities. Each subject had 2.22 ±â€Š1.10 types of CVJ abnormalities on average. In conclusion, comprehensive evaluation of CVJ abnormalities is recommended for differential diagnosis of subjects with unexplained torticollis. Once CVJ abnormalities are identified, concurrent abnormalities of other vertebrae need to be evaluated.

Complete occipitalization of the atlas with bilateral external auditory canal atresia.

Fusion of the atlas with the occipital bone is a rare congenital dysplasia known as occipitalization of the atlas, occipitocervical synostosis, assimilation of the atlas, or atlanto-occipital fusion. It is a component of the paraxial mesodermal maldevelopment and commonly associated with other dysplasias of the craniovertebral junction. External auditory canal atresia or external aural atresia is a rare congenital absence of the external auditory canal. It occurs as the consequence of the maldevelopment of the first pharyngeal cleft due to defects of cranial neural crest cells migration and/or differentiation. It is commonly associated with the dysplasias of the structures derived from the first and second pharyngeal arches including microtia. We present the coexistence of the occipitalization of the atlas and congenital aural atresia, an uncommon combination of the paraxial mesodermal maldevelopment, and defects of cranial neural crest cells. The association is most probably syndromic as minimal diagnostic criteria for the oculoariculovertebral spectrum are fulfilled. From the clinical point of view, it is important to be aware that patients with microtia must obtain also appropriate diagnostic imaging studies of the craniovetebral junction due to eventual concomitant occipitalization of the atlas and frequently associated C1-C2 instability.

Ruptured Aneurysms of the Occipital Artery Associated with Congenital Occipital Bone Defect.

BACKGROUND: Traumatic aneurysms of the superficial temporal artery have been frequently reported in the literature, whereas traumatic aneurysms of the occipital artery (OA) are extremely rare. CASE DESCRIPTION: A 30-year-old man had been followed at another hospital for meningoencephalocele associated with his congenital occipital bone defect. He was admitted to our hospital with a chief complaint of neck swelling and pain during a football game. Computed tomography and magnetic resonance imaging showed a hematoma in his right neck along with the meningoencephalocele. In addition, it showed an atrophic cerebellum with a cyst protruding from his occipital bone defect. Digital subtraction angiography of the right OA showed 3 aneurysms responsible for the large hematoma in his neck. Endovascular embolization with 20% N-butyl-2-cyanoacrylate was performed for treatment of the ruptured aneurysms followed by emergent surgical evacuation of the hematoma. An occipital cranioplasty with titanium mesh was performed 10 months after the emergent intervention. CONCLUSIONS: In this patient, the congenital occipital bone defect with meningoencephalocele might have been the remote source of risk for traumatic pseudoaneurysms along the muscle branches of the OA.

The Phenotypes of Spheno-Occipital Synchondrosis in Patients With Crouzon Syndrome.

OBJECTIVE: To characterize the phenotypes of spheno-occipital synchondrosis (SOS) in Chinese patients with Crouzon syndrome. METHODS: Twelve patients with Crouzon syndrome were included in this retrospective study, and were divided into 2 groups. The first group included 5 patients (5-7-year old), whereas 7 patients were included in the second group (8-11-year old). Two age- and sex-matched control groups were constituted for comparison. All patients and controls were underwent preoperative computed tomography examinations of the craniofacial area, and the three-dimensional skull models, sagittal, and axial images were reconstructed. The density of the SOS region was also calculated. RESULTS: The SOS was partially closed in the first Crouzon patients group, whereas the SOS was open in control groups. The SOS was completely fused SOS in the second Crouzon patients group, whereas the SOS was open or partially closed in control groups. There also were short and hypoplastic sphenoid bone in both Crouzon groups when compared with controls. In addition, the average density of SOS in patients with Crouzon syndrome was higher than the control groups (P <0.01). CONCLUSIONS: The SOS begins to prematurely fuse in Chinese patients with Crouzon syndrome, and there are short and hypoplastic sphenoid bone in these patients. Although a definitive role of prematurely fused SOS in Crouzon syndrome cannot be drawn, our finds provide important clues into the mechanisms, and potentially provide a treatment target for midfacial and cranial vault hypoplasia in Crouzon patients.

Persistent proatlas with additional segmentation of the craniovertebral junction - The Tsuang-Goehmann-Malformation.

Case study description and analysis of a complex craniovertebral dysplasia in an 8-year-old male patient, in which conventional cervical spine radiographs demonstrated a regularly differentiated occipital base, as well as the presence of two lateral masses of the proatlas vertebra and two lateral masses of the atlas vertebra. Further assessment included computed tomography of the occipital base and the upper cervical spine as well as three-dimensional reconstruction. Malsegmentation of the fourth occipital vertebra can result in various anomalies that are known as 'manifestation of the proatlas'. The occurrence of a persistent proatlas with additional segmentation of the craniovertebral junction represents an extremely rare dysplasia. To our knowledge, it is the second report concerning the persistence of a complete human proatlas vertebra. We consider the biomechanical and embryological particularities of this complex dysplasia to represent sufficient basis for future differentiation from other malformations of the fourth occipital vertebra. Comprehensive literature review and discussion about the entity will be provided.

Isolated Unilateral Frontosphenoidal Craniosynostosis: A Rare Cause of Anterior Plagiocephaly.

Isolated unilateral frontosphenoidal synostosis is a rare and often misdiagnosed cause of synostotic frontal plagiocephaly. It is important to distinguish the various synostotic causes of frontal plagiocephaly from deformational frontal plagiocephaly because operative intervention is required in synostotic plagiocephaly to avoid progressive deformity, whereas deformational plagiocephaly typically improves without surgery. This study reports a patient with a unique case of anterior plagiocephaly caused by left-sided frontosphenoidal craniosynostosis. The workup should include a thorough history and clinical examination followed by computed tomography scan with three-dimensional reconstruction. Frontosphenoidal synostosis should be suspected in the absence of a coronal synostosis in a child with anterior unilateral plagiocephaly and treated surgically. Good aesthetic and functional results occur with prompt diagnosis and early surgical correction.

The formation of the foramen magnum and its role in developing ventriculomegaly and Chiari I malformation in children with craniosynostosis syndromes.

OBJECT: Craniosynostosis syndromes are characterized by prematurely fused skull sutures, however, less is known about skull base synchondroses. This study evaluates how foramen magnum (FM) size, and closure of its intra-occipital synchondroses (IOS) differ between patients with different craniosynostosis syndromes and control subjects; and whether this correlates to ventriculomegaly and/or Chiari malformation type I (CMI), intracranial disturbances often described in these patients. METHODS: Surface area and anterior-posterior (A-P) diameter were measured in 175 3D-CT scans of 113 craniosynostosis patients, and in 53 controls (0-10 years old). Scans were aligned in a 3D multiplane-platform. The frontal and occipital horn ratio was used as an indicator of ventricular volume, and the occurrence of CMI was recorded. Synchondroses were studied in scans with a slice thickness ≤1.25 mm. A generalized linear mixed model and a repeated measures ordinal logistic regression model were used to study differences. RESULTS: At birth, patients with craniosynostosis syndromes have a smaller FM than controls (p < 0.05). This is not related to the presence of CMI (p = 0.36). In Crouzon-Pfeiffer patients the anterior and posterior IOS fused prematurely (p < 0.01), and in Apert patients only the posterior IOS fused prematurely (p = 0.028). CONCLUSION: The FM is smaller in patients with craniosynostosis syndromes than in controls, and is already smaller at birth. In addition to the timing of IOS closure, other factors may influence FM size.

Intraoperative electrophysiological monitoring during posterior craniocervical distraction and realignment for congenital craniocervical anomaly.

PURPOSE: Congenital craniocervical segmentation anomaly associated with malalignment of the odontoid process causes progressive spinal cord compression with myelopathy. Recent literatures have reported that ventral decompression could be achieved with posterior craniocervical realignment through posterior instrumented reduction. The purpose of the present study is to show the efficacy of intraoperative electrophysiological monitoring during craniocervical realignment through screws and rod system for congenital craniocervical segmentation anomaly. METHODS: Consecutive ten patients with a congenital craniocervical segmentation anomaly and myelopathy due to a malaligned odontoid process, who underwent posterior craniocervical realignment, were included. Klippel-Feil syndrome (KFS) was combined in four patients. Gait disturbance and motor weakness were the main presentation. Craniocervical realignment was achieved by intraoperative distraction through a rod and screw system. Intraoperative neuromonitoring was performed with transcranial motor-evoked potential (TcMEP) and somatosensory-evoked potential (SSEP). RESULTS: Significant change in TcMEP occurred in two patients with KFS during surgery, but the change was reversed with release of distraction. All patients were awakened without neurological deficit. Motor weakness and gait disturbance were normalized within 6 months in all patients. Postoperative computed tomography scan and/or magnetic resonance imaging showed that the reduction was complete in all patients. CONCLUSIONS: Craniocervical realignment through screws and rod system may be safe and efficacious surgical technique for the treatment of congenital craniocervical anomaly with the help of intraoperative neuromonitoring. However, distraction should be cautiously monitored, especially when Klippel-Feil syndrome is combined.

Ophthalmic findings in children with nonsyndromic craniosynostosis treated by expansion cranioplasty.

The ocular and systemic abnormalities of nonsyndromic craniosynostosis are often considered to be less severe than those of syndromic craniosynostosis and are less well described. The purpose of this article was to describe the frequency and nature of ophthalmic abnormalities in children treated for nonsyndromic craniosynostosis by expansion cranioplasty. A retrospective review identified 88 consecutive children with nonsyndromic craniosynostosis who underwent expansion cranioplasty with distraction osteogenesis. Assessment of presence and type of strabismus, refractive error, and amblyopia before and 6 months after surgery was recorded. Children with a mean age of 24.4 months were treated for nonsyndromic craniosynostosis (27 with coronal and 61 with sagittal and/or lambdoid). One-fourth of the patients had a fixation preference. Significant refractive errors were found in 45 (51%) of the 88 patients: hyperopia in 27%, myopia in 5%, and astigmatism in 35%. Anisometropia was present in 20%. Of the 85 patients who completed orthoptic examination, 48 (56%) had strabismus: exodeviation in 26%, esodeviation in 14%, and vertical deviation in 5%. Fourteen patients (16%) had abnormal head posture. Significant refractive error and strabismus were more likely to occur in cases with coronal synostosis. The procedures used for cranial vault expansion improved the abnormal head posture but did not affect the refractive error or ocular misalignment. Of children with nonsyndromic craniosynostosis who need neurosurgical correction, more than half were found to have significant refractive error and strabismus. Our findings support the importance of ophthalmic evaluation in these children.

Occipital plagiocephaly: unilateral lambdoid synostosis versus positional plagiocephaly.

OBJECTIVE: We defined parameters that could differentiate between positional and synostotic plagiocephaly and defined a diagnostic chart for decision making. DESIGN: Prospective study. SETTING: We examined 411 children with non-syndromic skull abnormalities between January 2011 and December 2012. PARTICIPANTS: A total of 8 infants under 1 year of age with proven unilateral non-syndromic lambdoid synostosis (LS) and 261 children with positional deformity were examined to outline the specific clinical features of both diagnoses. After clinical examination, an ultrasound revealed either a closed suture suggestive of LS or a patent lambdoid suture suggestive of positional deformity. For patients with synostosis, plain radiographs, MR imaging and follow-up examinations were performed. In cases of open sutures, only follow-ups were completed. MAIN OUTCOME MEASURE: Clinical, imaging, genesis and treatment differences between positional plagiocephaly and LS. RESULTS: In all 8 cases of unilateral LS and 258 cases of positional plagiocephaly, the diagnosis was established by clinical examination alone. In three cases of positional plagiocephaly, diagnosis was determined after an additional ultrasonography. MR imaging revealed a unilateral tonsillar herniation in five of the eight children with LS and hydrocephalus in one child. CONCLUSIONS: We have suggested a list of clinical features that specify the underlying cause of posterior plagiocephaly. An additional ultrasound scanning confirmed the diagnosis without any risks of ionising radiation or sedation as in a CT scan.

Incidence of basilar invagination in patients with tonsillar herniation? A case control craniometrical study.

A retrospective case-control study based on craniometrical evaluation was performed to evaluate the incidence of basilar invagination (BI). Patients with symptomatic tonsillar herniation treated surgically had craniometrical parameters evaluated based on CT scan reconstructions before surgery. BI was diagnosed when the tip of the odontoid trespassed the Chamberlain's line in three different thresholds found in the literature: 2, 5 or 6.6 mm. In the surgical group (SU), the mean distance of the tip of the odontoid process above the Chamberlain's line was 12 mm versus 1.2 mm in the control (CO) group (p<0.0001). The number of patients with BI according to the threshold used (2, 5 or 6.6 mm) in the SU group was respectively 19 (95%), 16 (80%) and 15 (75%) and in the CO group it was 15 (37%), 4 (10%) and 2 (5%).

Incidence of basilar invagination in patients with tonsillar herniation ? a case control craniometrical study / Incidência da invaginação basilar com heriação tonsilar ? estudo da craniometria do tipo caso-controle

A retrospective case-control study based on craniometrical evaluation was performed to evaluate the incidence of basilar invagination (BI). Patients with symptomatic tonsillar herniation treated surgically had craniometrical parameters evaluated based on CT scan reconstructions before surgery. BI was diagnosed when the tip of the odontoid trespassed the Chamberlain’s line in three different thresholds found in the literature: 2, 5 or 6.6 mm. In the surgical group (SU), the mean distance of the tip of the odontoid process above the Chamberlain’s line was 12 mm versus 1.2 mm in the control (CO) group (p<0.0001). The number of patients with BI according to the threshold used (2, 5 or 6.6 mm) in the SU group was respectively 19 (95%), 16 (80%) and 15 (75%) and in the CO group it was 15 (37%), 4 (10%) and 2 (5%).

Realizamos estudo retrospectivo tipo caso-controle baseado na avaliação craniométrica para avaliar a incidência da Invaginação Basilar (IB). Pacientes com herniação tonsilar sintomática tratada cirurgicamente foram avaliados quanto a parâmetros craniométricos obtidos em reconstrução de TC antes da cirurgia. IB foi diagnosticada quando a ponta do odontóide passava acima da linha de Chamberlain em 2, 5 ou 6,6 mm. No grupo cirúrgico (CI), a distância média da ponta do odontóide acima da linha de Chamberlain foi de 12 mm versus 1,2 mm no grupo controle (CO) (p<0.0001). O número de pacientes com IB conforme o critério diagnóstico usado (2, 5 ou 6,6 mm) foi de 19 (95%), 16 (80%) e 15 (75%) no grupo CI, respectivamente, contra 15 (37%), 4 (10%) e 2 (5%) no grupo CO. Pacientes com herniação tonsilar tinham maior incidência de IB comparados ao grupo controle.