1-Serviço de Medicina Física e de Reabilitação, Área de Pediatria, Hospital Dona Estefânia, Centro Hospitalar Universitário de Lisboa Central, Lisboa
- Reunião internacional – comunicação oral e poster: European Achondroplasia Forum 2023
BACKGROUND: Foramen magnum stenosis (FMS) is a frequent complication in achondroplasia. During the first year of life, foramen magnum is smaller and with a diminished growth rate. International Consensus Statement 2022 suggests clinical monitoring for FMS at least in the first 3 years. If the child has no symptoms, it’s recommended to screen with cranio-cerebral-cervical magnetic resonance imaging (MRI) in the first 3-6 months of life, and subsequently in an if-needed basis. As MRI access is onerous and with delay, health care professionals may deal with the possibility of FMS in the absence of symptoms. Rehabilitation may be limited by the fear of iatrogeny. Having an accessible and manageable imaging tool would be important, namely Point of Care Ultrasound (POCUS).
METHODS: Review of the evidence on FM ultrasound imaging in new-borns and infants. Development of a POCUS FMS screening.
RESULTS: POCUS is disseminated in several medical specialities. Studies demonstrate its usefulness and ease with which an adequate level of structure identification is achieved, after proper training. US performed via the FM is better at detecting new-born and infant anomalies in posterior fossa structures than via the anterior fontanelle. Its use in morphometric measurements of the brainstem has been attested.
Proposed POCUS protocol to perform regular evaluations in the first year of life:
- Static and dynamic visualization of craniocervical structures.
- Visualization of the patency of the subarachnoid space at the plane of foramen magnum on static evaluation.
Examination technique:
-A sectorial or micro convex probe is used for the examination of the craniocervical junction with a frequency of 7.5 MHz.
-Static evaluation: The patient in a lateral decubitus; the neck in a slightly flex position (15º).
A) In the sagittal section, at the level of the craniocervical junction, observe: the basion and opistion (consider abnormal if protuberant into the vertebral canal); the spinal cord, the subarachnoid space.
-Dynamic evaluation of above A), with </=50º flexion and </=30ºextension of the neck.
Proposed POCUS FMS score:
|
ITEM |
SCORE (0= NORMAL; 1= ABNORMAL) |
|
Static evaluation |
|
|
Basion and Opistion |
|
|
Patency of subarachnoid space at FM level |
|
|
Dynamic evaluation |
|
|
50 degrees of flexion à narrowing of the ventral subarachnoid space < 40% and a widening of the dorsal subarachnoid space of <80% (compared with the neutral position, 0 degrees). |
|
|
30 degrees of extensionà increase in the diameter of the ventral subarachnoid space <10%; the dorsal subarachnoid space reduced <20%. |
|
|
MRI evaluation if: |
Total score =/> 2 |
CONCLUSIONS: POCUS FMS screening might bring a breakthrough filling in the gaps on the current guidelines. The possibility to further deepen this issue and to find partners willing to evaluate the correlation of the proposed protocol to clinical and MRI findings, in a multicentre prospective study, is our proposition to the EAF on the 2023 meeting.
Palavras Chave: Acondroplasia, despiste, ecografia, estenose do foramen magnum