Functional magnetic resonance imaging of the pediatric swallow: imaging the cortex and the brainstem.

OBJECTIVE

To design and implement a functional magnetic resonance imaging (fMRI) protocol to investigate the cortical and brainstem patterns of activity in children with regard to the act of swallowing.

STUDY DESIGN

Pilot study to assess the clinical feasibility of the project.

METHODS

Using a 3T Bruker Biospec 30/60 MRI scanner, images were obtained using the Behavior Interleaved Gradient/Blood Oxygen Level Dependent (BIG-BOLD) image acquisition method. Initially, regions of interest (ROI) were developed to identify the mean time from the onset of a swallow to maximum cortical blood flow in the motor cortex. Using this data to design the BIG-BOLD acquisition method followed by postprocessing of the data, images from two volunteer adults and four volunteer children were obtained.

RESULTS

The average time from the onset of a swallow to maximum cortical blood flow was 6 to 8 seconds. Regions of cortical activity include pre- and post-central gyrus (Brodmann's areas 3 and 4), superior motor cortex (B.A. 24), insula, inferior frontal cortex (B.A. 44 and 45), Heschl gyrus (B.A. 41 and 42), putamen, globus pallidus, and the superior temporal gyrus (B.A. 38). Of particular note is the first mapping of the functional activity of swallowing at the level of the brainstem; activity was seen in the region of the nucleus ambiguous.

CONCLUSIONS

fMRI provides a novel means of studying the central processes of both normal swallowing and its various pathologic forms in children. Further understanding of how a child coordinates a swallow and how this coordination can be altered at the level of the brainstem and cortex may aid in the development of novel rehabilitative strategies.