Pediatric Chiari type 1 deformity

Epidemiology

Chiari type 1 deformity is commonly seen in pediatric neurology, neuroradiology, and neurosurgery and may have various clinical presentations depending on patient age. In addition, Chiari type 1 deformity is increasingly found by neuroimaging studies as an incidental finding in asymptomatic children 1).

Treatment

The ideal management in children regarding surgical and radiographic decision making is not clearly delineated.

Entezami et al., from the Department of Neurosurgery, AlbanyThomas Jefferson University, , Brown University, Providence, retrospectively reviewed a cohort of patients age 18 years and younger referred to a single neurosurgeon for CM1. Baseline MRIs of the spine were obtained. Non-operative patients had repeat imaging at 6-12 months. Patients who underwent an operation (decompression with/without duraplasty) had repeat imaging at 6 months.

One hundred and thirty-two patients with mean age of 10 years met inclusion criteria. All patients had post-operative symptomatic improvement.

They identified 26 patients with syrinx, 8 with scoliosis, 3 with hydrocephalus, and one had tethered cord. The average tonsillar descent was 8.1 mm in the non-operative group and 11.9 mm in the operative group. Ninety-five patients were managed conservatively (72%). Thirty-seven were offered surgery (28%), and 33 patients underwent intervention; 21 with duraplasty (64%) and 12 without (36%).

Pediatric patients with CM1 require both clinical and radiographic follow-up. Duraplasty may be performed if decompression fails to relieve symptomatology, but is not always needed. CM1 continues to present a challenge in surgical decision making. Adhering to a treatment paradigm may help alleviate difficult decision-making 2).

Chiari malformation Type I (CM-I) related to syndromic craniosynostosis in pediatric patients has been well-studied. The surgical management consists of cranial vault remodeling with or without posterior fossa decompression.

Outcome

Efforts to guide preoperative counseling and improve outcomes research are impeded by reliance on small, single-center studies.

Approximately 1 in 8 pediatric CM-I patients experienced a surgical complication, whereas medical complications were rare. Although complex chronic conditions (CCC) were common in pediatric CM-I patients, only hydrocephalus was independently associated with increased risk of surgical events. These results may inform patient counseling and guide future research efforts 3).

CM-I in children is not a radiologically static entity but rather is a dynamic one. Radiological changes were seen throughout the 7 years of follow-up. A reduction in tonsillar herniation was substantially more common than an increase. Radiological changes did not correlate with neurological examination finding changes, symptom development, or the need for future surgery. Follow-up imaging of asymptomatic children with CM-I did not alter treatment for any patient. It would be reasonable to follow these children with clinical examinations but without regular surveillance MRI 4).

Outcome assessment for the management of Chiari malformation type 1 is difficult because of the lack of a reliable and specific surgical outcome assessment scale. Such a scale could reliably correlate postoperative outcomes with preoperative symptoms.

Outcome is poor in approximately 3 in 10 patients 5).

The degree of tonsillar herniation has not been a reliable predictor of either symptom severity 6) or surgical outcome 7).

Arnautovic et al. identified 145 operative series of patients with CM-I, primarily from the United States and Europe, and divided patient ages into 1 of 3 categories: adult (> 18 years of age; 27% of the cases), pediatric (≤ 18 years of age; 30%), or unknown (43%). Most series (76%) were published in the previous 21 years. The median number of patients in the series was 31. The mean duration of the studies was 10 years, and the mean follow-up time was 43 months. The peak ages of presentation in the pediatric studies were 8 years, followed by 9 years, and in the adult series, 41 years, followed by 46 years. The incidence of syringomyelia was 65%. Most of the studies (99%) reported the use of posterior fossa/foramen magnum decompression. In 92%, the dura was opened, and in 65% of these cases, the arachnoid was opened and dissected; tonsillar resection was performed in 27% of these patients. Postoperatively, syringomyelia improved or resolved in 78% of the patients. Most series (80%) reported postoperative neurological outcomes as follows: 75% improved, 17% showed no change, and 9% experienced worsening. Postoperative headaches improved or resolved in 81% of the patients, with a statistical difference in favor of the pediatric series. Postoperative complications were reported for 41% of the series, most commonly with CSF leak, pseudomeningocele, aseptic meningitis, wound infection, meningitis, and neurological deficit, with a mean complication rate of 4.5%. Complications were reported for 37% of pediatric, 20% of adult, and 43% of combined series. Mortality was reported for 11% of the series. No difference in mortality rates was seen between the pediatric and adult series 8).

Case reports

A 16-year-old boy who admitted with symptoms related to CM-I. With careful examination and further genetic investigations, a diagnosis of Crouzon syndrome was made, of which the patient and his family was unaware before. The patient underwent surgery for posterior fossa decompression and followed-up for Crouzon’s syndrome.

This is the only case report indicating a late adolescent diagnosis of Crouzon syndrome through clinical symptoms of an associated CM-I 9).

References

1)

Poretti A, Ashmawy R, Garzon-Muvdi T, Jallo GI, Huisman TA, Raybaud C. Chiari Type 1 Deformity in Children: Pathogenetic, Clinical, Neuroimaging, and Management Aspects. Neuropediatrics. 2016 Jun 23. [Epub ahead of print] PubMed PMID: 27337547.
2)

Entezami P, Gooch MR, Poggi J, Perloff E, Dupin M, Adamo MA. Current management of pediatric chiari type 1 malformations. Clin Neurol Neurosurg. 2018 Dec 10;176:122-126. doi: 10.1016/j.clineuro.2018.12.007. [Epub ahead of print] PubMed PMID: 30557765.
3)

Greenberg JK, Olsen MA, Yarbrough CK, Ladner TR, Shannon CN, Piccirillo JF, Anderson RC, Wellons JC 3rd, Smyth MD, Park TS, Limbrick DD Jr. Chiari malformation Type I surgery in pediatric patients. Part 2: complications and the influence of comorbid disease in California, Florida, and New York. J Neurosurg Pediatr. 2016 May;17(5):525-32. doi: 10.3171/2015.10.PEDS15369. Epub 2016 Jan 22. PubMed PMID: 26799408.
4)

Whitson WJ, Lane JR, Bauer DF, Durham SR. A prospective natural history study of nonoperatively managed Chiari I malformation: does follow-up MRI surveillance alter surgical decision making? J Neurosurg Pediatr. 2015 Aug;16(2):159-66. doi: 10.3171/2014.12.PEDS14301. Epub 2015 May 1. PubMed PMID: 25932776.
5)

Aliaga L, Hekman KE, Yassari R, Straus D, Luther G, Chen J, Sampat A, Frim D. A novel scoring system for assessing Chiari malformation type I treatment outcomes. Neurosurgery. 2012 Mar;70(3):656-64; discussion 664-5. doi: 10.1227/NEU.0b013e31823200a6. PubMed PMID: 21849925.
6)

Khan AA, Bhatti SN, Khan G, et al. Clinical and radiological findings in Arnold Chiari malformation. J Ayub Med Coll Abbottabad. 2010;22(2):75-78.
7)

NoudelR,GomisP,SotoaresG,etal.Posteriorfossavolumeincreaseaftersurgery for Chiari malformation type I: a quantitative assessment using magnetic resonance imaging and correlations with the treatment response. J Neurosurg. 2011;115(3): 647-658.
8)

Arnautovic A, Splavski B, Boop FA, Arnautovic KI. Pediatric and adult Chiari malformation Type I surgical series 1965-2013: a review of demographics, operative treatment, and outcomes. J Neurosurg Pediatr. 2015 Feb;15(2):161-77. doi: 10.3171/2014.10.PEDS14295. Epub 2014 Dec 5. PubMed PMID: 25479580.
9)

Canpolat A, Akçakaya MO, Altunrende E, Ozlü HM, Duman H, Ton T, Akdemir O. Chiari Type I malformation yielded to the diagnosis of Crouzon syndrome. J Neurosci Rural Pract. 2014 Jan;5(1):81-3. doi: 10.4103/0976-3147.127885. PubMed PMID: 24741262.

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