Retrospective Study of Foramen Magnum Development in Patients with Achondroplasia Starting Vosoritide Before Age Three.
Early administration of vosoritide may promote foramen magnum development in young children with achondroplasia, but the clinical significance of these findings remains uncertain.
Where it sits
this study against the rest of the vosoritide corpusSummary and findings
This study evaluated the impact of early vosoritide administration on foramen magnum development in nine infants and young children with achondroplasia. Vosoritide was initiated at a median age of 4 months, with a mean treatment duration of 2.5 years. The study found that most patients showed steeper growth rates in foramen magnum diameters compared to untreated cohorts.
Abstract
<h4>Purpose</h4>Achondroplasia (ACH) is a monogenic skeletal dysplasia caused by gain-of-function variants in FGFR3, leading to impaired endochondral ossification and foramen magnum stenosis. Although vosoritide promotes endochondral ossification, its effects on foramen magnum development remain unclear. We evaluated the impact of early vosoritide administration on foramen magnum development in infants and young children with ACH using longitudinal magnetic resonance imaging (MRI).<h4>Methods</h4>This retrospective single-center case series included nine patients who initiated vosoritide before age 3. Serial head MRI scans were analyzed. Anteroposterior and transverse diameters of the foramen magnum were measured and compared with reference curves from untreated ACH cohorts. Stenosis severity was assessed using the Achondroplasia Foramen Magnum Score (AFMS). Correlations between changes in body height standard deviation score (SDS) and foramen magnum dimensions were assessed.<h4>Results</h4>Vosoritide was initiated at a median age of 4 months, with a mean treatment duration of 2.5 years. Compared with untreated cohorts, steeper growth rates were observed in eight of nine patients for the anteroposterior and in all for the transverse diameter. Most remained at AFMS 1-2. One progressed to AFMS 3 and underwent decompression surgery at 11 months. No significant correlation was identified between changes in body height SDS and foramen magnum diameter.<h4>Conclusion</h4>Early vosoritide administration may promote foramen magnum development in infants and young children with ACH, independent of systemic growth effects. Even when height improvement is limited, enhancement of foramen magnum growth may be clinically relevant.
Background
This paper addresses the effects of vosoritide on foramen magnum development in patients with achondroplasia, a condition characterized by impaired endochondral ossification. Prior knowledge indicates that vosoritide promotes endochondral ossification, but its specific impact on foramen magnum dimensions was not well understood. This study is significant as it explores a potential benefit of early intervention in a critical area affected by achondroplasia.
Methods
The study utilized a retrospective single-center case series design involving nine patients who started vosoritide treatment before the age of three. The treatment was initiated at a median age of 4 months, and the mean duration of treatment was 2.5 years. Serial head MRI scans were analyzed to measure the anteroposterior and transverse diameters of the foramen magnum, which were compared with reference curves from untreated cohorts.
Results
The primary endpoint observed was that eight of nine patients exhibited steeper growth rates for the anteroposterior diameter of the foramen magnum compared to untreated cohorts. All patients showed steeper growth rates for the transverse diameter. Most patients maintained an Achondroplasia Foramen Magnum Score of 1-2, with one patient progressing to AFMS 3 and requiring decompression surgery at 11 months.
Interpretation
The findings suggest that early vosoritide administration may enhance foramen magnum growth, independent of systemic growth effects. However, the effect sizes observed may not be clinically significant given the small sample size and lack of statistical correlation with changes in body height SDS. The limitations of the study, including its retrospective nature and small n, restrict the ability to draw firm conclusions about the efficacy of vosoritide in this context.
Key findings
- Vosoritide was initiated at a median age of 4 months.
- Mean treatment duration was 2.5 years.
- Steeper growth rates were observed in eight of nine patients for the anteroposterior diameter.
- All patients showed steeper growth rates for the transverse diameter.
- Most patients remained at Achondroplasia Foramen Magnum Score (AFMS) 1-2.
Limitations
- small n=9 case series
- retrospective design
- single-center study
- no significant correlation with body height SDS