F1 Recommended investigations for Chiari type I malformation.
Foroughi M, Tam S.
The prevalence of Chiari type I malformation (CM-I) has been estimated to be between 1% in adults and up to 3% of the paediatric population. The majority are asymptomatic and not associated with any underlying pathology, such as hydrocephalus, syringomyelia or C1/C2 instability. The aim of this review was to appraise critically the benefits of various imaging modalities for diagnosing this malformation and its associated pathologies.
The authors reviewed the pertinent literature on the neuroradiology of the CM-I, giving special regard to magnetic resonance imaging (MRI) of the entire spine and brain, constructive interference in steady state (CISS) image MRI sagittal T2, Cine-MRI, and C1 or C2 flexion and extension imaging. A literature search was performed using PubMed and Embase databases and the search was focused on imaging techniques used to diagnose CM-I.
Results. MRI of the entire spine and brain enables one to assess for hydrocephalus, syringomyelia and tethered cord. Cine-MRI provides information on CSF pulsatility at the craniocervical junction, while CISS image MRI sagittal T2 allows better-quality visualisation of CSF around the cerebellum and tonsils. Both techniques provide useful additional details but are not mandatory CM-I diagnostic tools. CM-1 associated C1/C2 instability is not commonly seen in the UK but if suspected the use of C1/C2 flexion and extension X-rays and CT scan is recommended.
Asymptomatic CM-I hindbrain hernias without impaction do not need further investigations. Symptomatic or significant impaction CM-I hindbrain hernias should be investigated using MRI brain and entire spine, preferably using thin cut high resolution T2 weighted images of the craniocervical junction. Flexion and extension x-rays or CT scans are indicated only when instability of C1/C2 region is suspected. Cine MRI is not essential but can provide benefits for assessment of CSF flow.
The symposium is co-organised by The Ann Conroy Trust, in association with Aesculap Academia.
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