Abstract

Chiari malformation results in the downward displacement of the brain stem and cerebellum into the cervical portion of the spinal cord. There are four fundamental types of Chiari malformations (CM-I, CM-II, CM-III, and CM-IV) with variants (Chiari type 1.5 and 3.5), depending on the severity of the anatomical distortions and CSF blockage. Symptoms of Chiari malformations can range from asymptomatic (in uncomplicated CM-I) to life-threatening (in the more severe malformations). Diagnosis is typically suspected by signs and symptoms and confirmed by diagnostic imaging. Treatment can range from medications for pain relief (in CM-I) to surgery (in the more severe symptoms and malformations). CM-III and CM-IV have poor prognoses. An asymptomatic patient with CM-I can develop symptoms gradually over time or abruptly, secondary to trauma. Chiari malformation is one of the most common abnormalities affecting the craniovertebral junction and should be considered in the differential diagnosis of specific symptoms and circumstances.

Keywords: Chiari; Hydrocephalus; McRae Line; Meningomyelocele; Paresthesia; Syringomyelia; Valsalva Maneuver

References

1. Pakzaban P. “Chiari Malformation: Practice Essentials, Problem, Epidemiology”. Sickle Cell Anemia Differential Diagnoses (2018). https://emedicine.medscape.com/article/1483583-overview
2. Vannemreddy P., et al. “Congenital Chiari malformations”. Neurology India 1 (2010): 6-14. https://pubmed.ncbi.nlm.nih.gov/20228456/
3. Hassan ul., et al. “Arnold-Chiari Malformation: Anatomical Variations and Latest Embryological Perspective. Review of Literature”. International Journal of Contemporary Medical Research5 (2016): 1485-1491. https://www.researchgate.net/publication/327939323_Arnold-Chiari_Malformation_Anatomical_Variations_and_Latest_Embryological_Perspective_Review_of_Literature
4. Tubbs RS., et al. “Hindbrain herniation: A review of embryological theories”. Italian Journal of Anatomy and Embryology 1 (2008): 37-46. https://researchexperts.utmb.edu/en/publications/hindbrain-herniation-a-review-of-embryological-theories
5. Mayfield Brain and Spine. “Chiari I malformation”. Brain Anatomy, Anatomy of the Human Brain (2018).
6. Stevens JM., et al. “Chiari malformation in adults: relation of morphological aspects to clinical features and operative outcome”. Journal of Neurology, Neurosurgery, and Psychiatry 10 (1993): 1072-1077. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1015234/
7. Nash J., et al. “Chiari type I malformation: overview of diagnosis and treatment”. WMJ8 (2002): 35-40. https://www.researchgate.net/publication/10925213_Chiari_Type_I_Malformation_Overview_of_Diagnosis_and_Treatment
8. Spina A., et al. “Sudden onset of Chiari malformation type 1 in a young child after trauma”. Child's Nervous System 9 (2015): 1589-1594. https://www.researchgate.net/publication/276147007_Sudden_onset_of_Chiari_malformation_type_1_in_a_young_child_after_trauma
9. Murano T and Rella J. “Incidental finding of Chiari I malformation with progression of symptoms after head trauma: case report”. The Journal of Emergency Medicine 3 (2006): 295-298. https://pubmed.ncbi.nlm.nih.gov/16677981/
10. Wan MJ., et al. “Conversion to symptomatic Chiari I malformation after minor head or neck trauma”. Neurosurgery4 (2008): 748-753. https://academic.oup.com/neurosurgery/article-abstract/63/4/748/2558363?redirectedFrom=fulltext
11. Akbari SH., et al. “Surgical management of symptomatic Chiari II malformation in infants and children”. Child's Nervous System 7 (2013): 1143-1154. https://pubmed.ncbi.nlm.nih.gov/23388856/
12. Curnes JT., et al. “MR imaging of hindbrain deformity in Chiari II patients with and without symptoms of brainstem compression”. American Journal of Roentgenology 2 (1989): 293-302. http://www.ajnr.org/content/10/2/293
13. El Gammal T., et al. “MR imaging of Chiari II malformation”. American Journal of Roentgenology 1 (1988): 163-170. https://pubmed.ncbi.nlm.nih.gov/3257116/
14. Pollack IF., et al. “The effect of early craniocervical decompression on functional outcome in neonates and young infants with myelodysplasia and symptomatic Chiari II malformations: results from a prospective series”. Neurosurgery4 (1996): 703-710. https://academic.oup.com/neurosurgery/article-abstract/38/4/703/2849508?redirectedFrom=fulltext
15. Wolpert SM., et al. “Chiari II malformation: MR imaging evaluation”. American Journal of Roentgenology 5 (1987): 1033-1042. https://pubmed.ncbi.nlm.nih.gov/3499774/
16. Arora N., et al. “Bilateral Vocal Cord Palsy with Arnold Chiari Malformation: A Rare Case Series”. Journal of Clinical and Diagnostic Research 9 (2016): MR01-MR03. https://www.researchgate.net/publication/308224115_Bilateral_Vocal_Cord_Palsy_with_Arnold_Chiari_Malformation_A_Rare_Case_Series
17. Holinger PC., et al. “Respiratory obstruction and apnea in infants with bilateral abductor vocal cord paralysis, meningomyelocele, hydrocephalus, and Arnold-Chiari malformation”. The Journal of Pediatrics 3 (1978): 368-373. https://pubmed.ncbi.nlm.nih.gov/632975/
18. Almurshidi Medical Agency. “Chiari Malformation Treatment in Thailand” (2019).
19. Caldarelli M., et al. “Chiari type III malformation”. Child's Nervous System 5 (2002): 207-210. https://pubmed.ncbi.nlm.nih.gov/12042918/
20. Furtado SV., et al. “Repair of Chiari III malformation using cranioplasty and an occipital rotation flap: technical note and review of literature”. Surgical Neurology 4 (2009): 414-417. https://pubmed.ncbi.nlm.nih.gov/19147197/
21. Häberle J., et al. “Cervical encephalocele in a newborn--Chiari III malformation. Case report and review of the literature”. Child's Nervous System 6 (2001): 373-375. https://pubmed.ncbi.nlm.nih.gov/11417422/
22. Ivashchuk G., et al. “Chiari III malformation: a comprehensive review of this enigmatic anomaly”. Child's Nervous System 11 (2015): 2035-2040. https://pubmed.ncbi.nlm.nih.gov/26255148/
23. Jeong DH., et al. “Arnold-Chiari Malformation Type III With Meningoencephalocele: A Case Report”. Annals of Rehabilitation Medicine 3 (2014): 401-404. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4092183/
24. Rani H., et al. “Chiari III Malformation: a rare case with review of literature”. Fetal and Pediatric Pathology 3 (2013): 169-174. https://pubmed.ncbi.nlm.nih.gov/22621240/
25. Hadley DM. “The Chiari Malformation”. Journal of Neurology, Neurosurgery, and Psychiatry 72 .2 (2002): ii38-ii40. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1765588/
26. Azahraa Haddad F., et al. “The newer classifications of the chiari malformations with clarifications: An anatomical review”. Clinical Anatomy 3 (2018): 314-322. https://onlinelibrary.wiley.com/doi/abs/10.1002/ca.23051
27. Kim IK., et al. “Chiari 1.5 malformation : an advanced form of Chiari I malformation”. Journal of Korean Neurosurgical Society 4 (2010): 375-379. https://radiopaedia.org/articles/chiari-15-malformation
28. Malik A., et al. “Chiari 1.5: A lesser known entity”. Annals of Indian Academy of Neurology 4 (2015): 449-450. https://pubmed.ncbi.nlm.nih.gov/26713020/
29. Tubbs RS., et al. “A critical analysis of the Chiari 1.5 malformation”. Journal of Neurosurgery 2 (2004): 179-183. https://thejns.org/pediatrics/view/journals/j-neurosurg-pediatr/101/2/article-p179.xml
30. Fisahn C., et al. “The Chiari 3.5 malformation: a review of the only reported case”. Child's Nervous System 12 (2016): 2317-2319. https://link.springer.com/article/10.1007/s00381-016-3255-3
31. Tubbs RS., et al. “Chiari IV malformation: correcting an over one century long historical error”. Child's Nervous System  7 (2016): 1175-1179. https://pubmed.ncbi.nlm.nih.gov/26049716/
32. Arora R. “Imaging spectrum of cerebellar pathologies: a pictorial essay”. Polish Journal of Radiology 80 (2015): 142-150. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4364256/
33. Bejjani GK. “Definition of the adult Chiari malformation: a brief historical overview”. Neurosurgical Focus 1 (2001): E1. https://thejns.org/focus/view/journals/neurosurg-focus/11/1/foc.2001.11.1.2.xml
34. Hidalgo JA., et al. “Arnold Chiari Malformation” (2020).
35. Pearce JM. “Historical note. Arnold Chiari, or "Cruvilhier Cleland Chiari" malformation”. Journal of Neurology, Neurosurgery, and Psychiatry 1 (2000): 13. https://pubmed.ncbi.nlm.nih.gov/10671138/
36. Solt I. “Chiari malformation eponym- time for historical justice”. Ultrasound in Obstetrics and Gynecology 2 (2011): 250-251. https://obgyn.onlinelibrary.wiley.com/doi/full/10.1002/uog.8876
37. Tubbs RS., et al. “Chiari IV malformation: correcting an over one century long historical error”. Child's Nervous System 7 (2016): 1175-1179. https://pubmed.ncbi.nlm.nih.gov/26049716/