PT  - JOURNAL ARTICLE
AU  - Moira S Cheung
AU  - Melita Irving
AU  - Alessandra Cocca
AU  - Rui Santos
AU  - Meera Shaunak
AU  - Harry Dougherty
AU  - Ata Siddiqui
AU  - Paul Gringras
AU  - Dominic Thompson
TI  - Achondroplasia Foramen Magnum Score: screening infants for stenosis
AID  - 10.1136/archdischild-2020-319625
DP  - 2021 Feb 01
TA  - Archives of Disease in Childhood
PG  - 180--184
VI  - 106
IP  - 2
4099  - http://adc.bmj.com/content/106/2/180.short
4100  - http://adc.bmj.com/content/106/2/180.full
SO  - Arch Dis Child2021 Feb 01; 106
AB  - Background Achondroplasia is associated with foramen magnum stenosis (FMS) and significant risk of morbidity and sudden death in infants. A sensitive and reliable method of detecting infants who require decompressive surgery is required. This study aims to describe the incidence and severity of FMS in an unselected, sequential series of infants using a novel MRI score and retrospectively correlate severity with clinical examination and cardiorespiratory sleep (CRS) studies.Methods The Achondroplasia Foramen Magnum Score (AFMS) was developed and scores were retrospectively correlated with clinical and CRS data over a 3-year period.Results Of 36 infants (M:F, 18:18), 2 (5.6%) did not have FMS (AFMS0); 13 (36.1%) had FMS with preservation of the cerebrospinal fluid (CSF) spaces (AFMS1); 3 (8.3%) had FMS with loss of the CSF space but no spinal cord distortion (AFMS2); 13 (36.1%) had FMS with flattening of the cervical cord without signal change (AFMS3); and 5 (13.9%) had FMS resulting in cervical cord signal change (AFMS4). Mean Total Apnea and Hypopnea Index (TAHI) for AFMS0–4 was 3.4, 6.41, 2.97, 10.5 and 25.8, respectively. Severe TAHI had a specificity of 89% but only a 59% sensitivity for AFMS3–4. Neurological examination was normal in 34/36 (94%) patients. Overall, 9/36 (25%) infants required neurosurgery with minimal surgical complications.Conclusions Clinical examination and CRS have a low sensitivity for predicting the effects of foramen stenosis on the spinal cord. Routine screening with MRI using AFMS can aid in detecting early spinal cord changes and has the potential to reduce infant morbidity and mortality.