Chiari type 1 malformations and hypermobility spectrum disorder: clinical outcomes and the importance of the differential diagnosis.

objectiveThe impact of generalized hypermobility spectrum disorder (G-HSD) on the management of patients with a Chiari malformation type 1 (CM1) is poorly understood and is subject of continued controversy. The authors present a series of patients with G-HSD to demonstrate clinical course and outcomes of operative management and the importance of differentiating symptoms of a Chiari malformation from the often multiple and varied manifestations of G-HSD.

methodsThis study was conducted using prospectively collected data from patients evaluated for CM1 at a large tertiary pediatric neurosurgery clinic between April 2010 and September 2022. Patients diagnosed with G-HSD under 21-years of age were included.

resultsA total of 43 patients with G-HSD were included in this study of which 30 (69.8%) were female and 13 (30.2%) were male. The mean age at initial neurosurgical evaluation was 10.66 years (range: 1.5-20 years). The mean duration of clinical follow-up was 38.2 months (range: 1-216 months). For the entire cohort, 19 (43.8%) had a Chiari 1.5 malformation and 14 (32.6%) had syringomyelia. Patients with a Chiari 1.5, syringomyelia or a distance from basion-C2 (pB-C2) ≥ 9 mm were significantly more likely to undergo operative intervention. Surgery consisted of a suboccipital decompression with duraplasty in 8 patients (66.6%) and without duraplasty in 4 patients (33.3%). Ventral decompression (VD) was not needed in any patient over the follow-up period. Notably, occipitocervical fusion (OCF) was also not needed for any patient in our cohort over the follow-up period, irrespective of preoperative anatomical characteristics. At a mean postoperative follow-up of 38.2 months (range: 1-216 months) 94.1% patients had improvement or resolution of their preoperative symptoms and all patients (100%) with syringomyelia had improvement or resolution of their preoperative syrinx.

conclusionPatients with G-HSD were significantly more likely to require a Chiari decompression if their pB-C2 was ≥ 9 mm, they presented with a CM type 1.5 or had syringomyelia. Although many patients had features of a complex Chiari malformation, excellent postoperative outcomes were achieved using a suboccipital decompression alone for patients in which it was felt that their clinical problems were primarily referable to the CM. However, it remains paramount to accurately differentiate between symptoms for an associated Chiari malformation versus the myriad number of similar manifestations of G-HSD.