Factors predicting the occurrence of syringomyelia in patients with Chiari I malformations

Background: Chiari I malformations are defined as the downward herniation of cerebellar tonsils more than 5 mm through the foramen magnum. Syringomyelia is a common association of Chiari I malformation.Methods: This purpose of this study was to determine the various factors predicting the occurrence of syringomyelia in patients with Chiari I malformations. This retrospective study was conducted in Government medical college, Thrissur, Kerala, India. 27 patients admitted with diagnosis of symptomatic Chiari I malformations during the period of January 2015 to January 2019 were selected for the study.Results: The mean age was 22.8 years and syringomyelia was more common in patients older than 10 years (p value0.005). Females were 17(63%) and males were 10(37%) but there no difference in occurrence of syringomyelia among both sexes(p value is 0.16). Syringomyelia was present in 17(63%) cases. Association between various factors and syringomyelia measured by calculating P value which was 0.005 for age >10 years, 0.16 for sex, 0.093 for duration of symptoms >12 months, 0.05 for tonsillar descend >10mm and 0.097 for hypertension. The p value for the association of duration of symptoms >12months and extend of tonsillar descend is 0.001 Mean duration of symptoms (onset of first symptom to the time of presentation) was 16.3 months and syringomyelia was more common in patients with duration of symptoms more than 12 months but this difference was statistically not significant (p value 0.093). Mean tonsillar descend from the level of foramen magnum was 11.3 mms and syringomyelia was more common in patients with tonsillar herniation more than 10mm (p value 0.05). There is a statistically significant relationship between duration of symptoms more than 12 months and tonsillar descend more than 10mm(p value 0.001).There is no significant association between hypertension and occurrence of syringomyelia in patients with Chiari I malformation.Conclusions: Incidence of Chiari I Malformations is more among adults and it is slightly higher in females. Syringomyelia is a common association of Chiari I Malformations. The occurrence of syringomyelia in patients with Chiari I Malformations associated with increasing age of patients and extend of tonsillar herniation. There is no statistically significant association between syringomyelia and duration of symptoms or hypertension.

3-D simulation of posterior fossa reduction in Chiari I / Simulação em 3D da redução da fossa posterior no Chiari do tipo I

ABSTRACT We proposed a 3D model to evaluate the role of platybasia and clivus length in the development of Chiari I (CI). Using a computer aided design software, two DICOM files of a normal CT scan and MR were used to simulate different clivus lengths (CL) and also different basal angles (BA). The final posterior fossa volume (PFV) was obtained for each variation and the percentage of the volumetric change was acquired with the same method. The initial normal values of CL and BA were 35.65 mm and 112.66º respectively, with a total PFV of 209 ml. Ranging the CL from 34.65 to 29.65 – 24.65 – 19.65, there was a PFV decrease of 0.47% – 1.12% – 1.69%, respectively. Ranging the BA from 122.66º to 127.66º – 142.66º, the PFV decreased 0.69% – 3.23%, respectively. Our model highlights the importance of the basal angle and clivus length to the development of CI.

RESUMO No presente estudo, propusemos a criação de um modelo computacional em 3D com elaboração de software onde dois arquivos em formato DICOM com uma TC e RNM de crânio foram usados para simular diferentes mensurações na extensão do clivus (EC) e no ângulo basal (AB). O volume final da fossa posterior (VFP) foi obtido em cada variação, bem como a percentagem de volume alterada. O tamanho inicial da EC era de 35,65 mm e o do AB era de 112.66º, com um VFP de 209 ml. Variando a EC de 34,65 para 29,65 – 24.65 e 19.65, houve uma diminuição do VFP de 0.47%, 1.12% e 1.69%, respectivamente. Variando o AB de 122,66º para 127,66º e 142,66º, o VFP diminui para 0.69% e 3.23%, respectivamente. Nosso modelo enfatiza a importância da patogênese do aumento do AB e do encurtamento do clivus no desenvolvimento do Chiari I.

Modified cerebellar tonsillectomy combined with posterior fossa decompression via small-size craniotomy for Chiari- malformation associated with syringomyelia / 第二军医大学学报

Objective To explore a modified method of cerebellar tonsillectomy combined with posterior fossa decompression via small-size craniotomy for Chiari- malformation associated with syringomyelia and to evaluate its clinical efficacy. Methods The clinical data of 29 Chiari- malformation patients associated with syringomyelia, who underwent modified cerebellar tonsillectomy combined with posterior fossa decompression via small-size craniotomy from January 2012 to January 2014, were analyzed retrospectively.Patients were prone with head and neck in the coaxial position and received surgical intervention including posterior fossa decompression via small-size craniotomy, opening the rear atlas arch, resection of the inner part of cervical canal of the cerebellar tonsil herniation while keeping the integrity of soft meninges, adhesiolysis of median aperture of the fourth ventricle, dissection of the suture of arachnoid and dural edge to avoid latrogenic dead space, and suture of the dura with autologous fascia. The cerebrospinal fluid release rate of the whole process was controlled. Results A total of 24 patients were followed up after operation while 5 patients were lost in follow-up. The clinical symptom of 23 patients was improved within one year after operation. The repression of medulla oblongata and posterior upper part of cervical cord was removed in MRI examination 6 months after operation. The lower edge of cerebellar tonsillar was up to the plane above the foramen magnum and the herniation was resolved. The syringomyelia was shortened or disappeared. Conclusion Modified cerebellar tonsillectomy combined with posterior fossa decompression via small-size craniotomy, as a microscopy neurosurgery, is an effective method for the treatment of Chiari- malformation associated with syringomyelia.

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.

Cerebelite aguda com herniação tonsilar: relato de caso / Acute cerebellitis with tonsillar herniation: a case report

A cerebelite aguda é uma síndrome inflamatória rara frequentemente caracterizada por rápida disfunção cerebelar. Neste estudo relatamos os achados de imagem do caso de uma criança com cerebelite aguda, herniação tonsilar e hidrocefalia hipertensiva. O agente etiológico não foi descoberto. O tratamento foi conservador, com manitol e corticoide. A análise evolutiva por imagem demonstrou resolução do quadro clínico sem sequelas.

Acute cerebellitis is a rare inflammatory syndrome frequently characterized by fast onset of cerebellar dysfunction. The present case report describes imaging findings in a child with acute cerebellitis, tonsillar herniation and hypertensive hydrocephalus. The etiologic agent has not been determined. A conservative management was adopted, with corticoid and diuretic drugs. Imaging follow-up demonstrated resolution of the clinical condition with no sequela.

Chiari I Malformation Associated with Syringomyelia Treated with Foramen Magnum Decompression

The authors report two cases of Chiari I malformation associated with syringomyelia. The first is that of a 45-year-old woman with neck and shoulder pain and the other, a 24-year-old man with neck pain. In the former, MRI revealed caudal descent of the cerebellar tonsil to the C2 level and a large eccentric syrinx from the C2-T6 levels ; in the man, MRI showed caudal descent of the cerebellar tonsil to the C2 level and a large eccentric syrinx from the C2-T4 levels. We successfully treated these patients by foramen magnum decompression and duroplasty. Theories of Chiari I malformation associated with syringomyelia, as well as clinical signs and symptoms, and management techniques, are discussed.