Abstract
Over the years, knowledge regarding the natural history of Chiari malformation type I (CM-I) has improved. However, there are still uncertainties in the literature regarding asymptomatic and oligosymptomatic patients with CM-I. We performed a literature review in order to determine the natural history of CM-I in symptomatic patients who were not operated and in asymptomatic adult patients. Among symptomatic patients, the most frequent symptom was headache (77%). Cough-related headache alone (34%), migraine-related headache alone (21.4%), and both cough- and migraine-related headaches (21.8%) were the most prevalent forms of headache. Some symptoms improved more effectively with surgical treatment options; cough-related headaches improved by 95% following surgery and by 40% following conservative treatment. Other headache types improved by 93% and 61.5% following conservative and surgical treatments, respectively. Patients diagnosed with asymptomatic or oligosymptomatic CM-I may improve over time or stabilize with conservative treatment. There is great heterogeneity in the literature regarding the diagnostic criteria for CM-I. Owing to the heterogeneity among the articles identified for this review, there is no consensus regarding the precise indications for surgery in asymptomatic patients. The natural CM-I history in asymptomatic patients reveals a favorable evolution.
Highlights
BackgroundInitially, Chiari malformation type I (CM-I) was described as a group of cerebellar changes that develop owing due to hydrocephalus and that lead to an elongation of the cerebellar tonsils and medial portions of the lower lobes of the cerebellum towards the brainstem [1]
We found that some authors define CM-I as a condition in which the herniation of the cerebellar tonsils through the foramen magnum is equal to or greater than 5 mm [12,13,14,15,16,17,18,19]
In a recent review on the topic, McClugage and Oakes recommend the administration of surgical treatment to only those patients with symptoms directly related to Chiari or syringomyelia, and they propose that surgery is indicated in the following conditions: patients experiencing classic headaches induced by the Valsalva maneuver, patients with associated syringomyelia, and patients with neurological conditions associated with pathologies of the foramen magnum and cervical medullary junction or a dysfunction of the cranial nerves [28]
Summary
Chiari malformation type I (CM-I) was described as a group of cerebellar changes that develop owing due to hydrocephalus and that lead to an elongation of the cerebellar tonsils and medial portions of the lower lobes of the cerebellum towards the brainstem [1]. Foramen magnum decompression has been the most frequently employed surgical technique for the treatment of CM-I in symptomatic patients. The natural history and conservative treatment of symptomatic and asymptomatic patients who did not undergo surgery have seldom been discussed in the literature, and, we have no clear evidence regarding the appropriate treatment guidelines. In this study, we conducted a literature review of the natural history and conservative treatment of adult patients with CM-I, with the aim that our data could be used to assist surgeons in making decisions regarding the best approach that can be employed to treat these patients. How to cite this article Dantas F R, Dantas F, Caires A, et al (December 13, 2020) Natural History and Conservative Treatment Options in Chiari Malformation Type I in Adults: A Literature Update.
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