Patients with “benign” Chiari I malformations require surgical decompression at a low rate

Abstract

OBJECTIVEThere are sparse published data on the natural history of “benign” Chiari I malformation (CM-I)—i.e., Chiari with minimal or no symptoms at presentation and no imaging evidence of syrinx, hydrocephalus, or spinal cord signal abnormality. The purpose of this study was to review a large cohort of children with benign CM-I and to determine whether these children become symptomatic and require surgical treatment.METHODSPatients were identified from institutional outpatient records using International Classification of Diseases, 9th Revision, diagnosis codes for CM-I from 1996 to 2016. After review of the medical records, patients were excluded if they 1) did not have a diagnosis of CM-I, 2) were not evaluated by a neurosurgeon, 3) had previously undergone posterior fossa decompression, or 4) had imaging evidence of syringomyelia at their first appointment. To include only patients with benign Chiari (without syrinx or classic Chiari symptoms that could prompt immediate intervention), any patient who underwent decompression within 9 months of initial evaluation was excluded. After a detailed chart review, patients were excluded if they had classical Chiari malformation symptoms at presentation. The authors then determined what changes in the clinical picture prompted surgical treatment. Patients were excluded from the multivariate logistic regression analysis if they had missing data such as race and insurance; however, these patients were included in the overall survival analysis.RESULTSA total of 427 patients were included for analysis with a median follow-up duration of 25.5 months (range 0.17–179.1 months) after initial evaluation. Fifteen patients had surgery at a median time of 21.0 months (range 11.3–139.3 months) after initial evaluation. The most common indications for surgery were tussive headache in 5 (33.3%), syringomyelia in 5 (33.3%), and nontussive headache in 5 (33.3%). Using the Kaplan-Meier method, rate of freedom from posterior fossa decompression was 95.8%, 94.1%, and 93.1% at 3, 5, and 10 years, respectively.CONCLUSIONSAmong a large cohort of patients with benign CM-I, progression of imaging abnormalities or symptoms that warrant surgical treatment is infrequent. Therefore, these patients should be managed conservatively. However, clinical follow-up of such individuals is justified, as there is a low, but nonzero, rate of new symptom or syringomyelia development. Future analyses will determine whether imaging or clinical features present at initial evaluation are associated with progression and future need for treatment.

The Chiari I malformation

“…The natural history of asymptomatic or minimally symptomatic CIM is likely benign, with > 93% of patients remaining clinically stable or improving after serial imaging with several years of follow-up. 33,55 Thus, in this patient population, follow-up with serial imaging is a reasonable approach. This includes patients with non-Valsalva-induced headaches or atypical headaches, who should not be considered for surgery without more obvious referable symptoms.…”

The impact of imposed delay in elective pediatric neurosurgery: an informed hierarchy of need in the time of mass casualty crisis

“…Issues/threats with surgical delay: Supporting evidence Chiari I malformation has a range of clinical presentations from headaches to brainstem-related symptoms [24]. When patients are asymptomatic, the clinical course is benign overall [25,26]. However, neurologic deficits arising secondary to syringomyelia may not be reversible with surgery.…”

Chiari malformation and syringomyelia

“…69 An incidental finding of tonsillar descent, however, must be treated with caution, particularly in view of the known stability of tonsil position, and even ascent of the tonsils in some children. 50 Indications for surgery must be based on clinical assessment as well as imaging. The natural history of Chiari anomaly is such that patients with clinical manifestations of marginal or doubtful significance can be observed.…”

“…The natural history of Chiari anomaly is such that patients with clinical manifestations of marginal or doubtful significance can be observed. 50,68 Imaging studies can be repeated after an appropriate time interval, and progressive enlargement of a syrinx cavity, particularly when associated with clinical symptoms, may be an indication for surgical intervention. The rare spontaneous resolution of Chiari anomaly and syringomyelia has also been reported.…”