DTI-MRI Reveals Sensory-Processing Disorders in Children

The scientists discovered that children affected with SPD have quantifiable differences in brain structure, for the first time showing a biologic basis for the disease that differentiates it from other neurodevelopmental disorders.

SPDs are more prevalent in children than autism, and as typical as attention deficit hyperactivity (ADHD) disorder; however, the disorder receives far less attention partly because it has never been recognized as a distinct disease.

SPDs affect 5%-16% of school-aged children. Children with SPD struggle with how to process stimulation, which can cause a wide range of symptoms including hypersensitivity to sight, sound, and touch, poor fine motor skills, and easy distractibility. Some SPD children cannot tolerate load noises, whereas others struggle with social interaction or cannot hold a pencil. Furthermore, a sound that one day is an annoyance can the next day be sought out. The disorder can be inexplicable for parents and has been a source of a great deal of debate for clinicians.

“Most people don’t know how to support these kids because they don’t fall into a traditional clinical group,” said Elysa Marco, MD, who led the study along with postdoctoral fellow Julia Owen, PhD. Dr. Marco is a cognitive and behavioral child neurologist at University of California, San Francisco (UCSF) Benioff Children’s Hospital (USA; www.ucsfbenioffchildrens.org). “Sometimes they are called the ‘out of sync’ kids. Their language is good, but they seem to have trouble with just about everything else, especially emotional regulation and distraction. In the real world, they’re just less able to process information efficiently, and they get left out and bullied,” said Dr. Marco, who treats affected children in her cognitive and behavioral neurology clinic. “If we can better understand these kids who are falling through the cracks, we will not only help a whole lot of families, but we will better understand sensory processing in general. This work is laying the foundation for expanding our research and clinical evaluation of children with a wide range of neurodevelopmental challenges—stretching beyond autism and ADHD [attention deficit hyperactivity disorder].”

In the study, researchers used a sophisticated type of MRI called DTI, which gauges the microscopic movement of water molecules within the brain to provide valuable data about the brain’s white matter tracts. DTI shows the direction of the white matter fibers and the integrity of the white matter. The brain’s white matter is crucial for thinking, perceiving, and learning.

The study assessed 16 boys, between the ages of eight and 11, with SPD but without a diagnosis of autism or prematurity, and compared the results with 24 typically developing boys who were matched for age, gender, right- or left-handedness, and IQ. The patients’ and control study participants’ behaviors were first classified using a parent report measure of sensory behavior called the sensory profile.

One of the reasons SPD has been overlooked until now is that it often occurs in children who also have ADHD or autism, and the disorders have not been listed in the Diagnostic and Statistical Manual used by psychiatrists and psychologists. “Until now, SPD hasn’t had a known biological underpinning,” said senior author Pratik Mukherjee, MD, PhD, a professor of radiology and biomedical imaging and bioengineering at UCSF. “Our findings point the way to establishing a biological basis for the disease that can be easily measured and used as a diagnostic tool,” Dr. Mukherjee said.

The imaging detected abnormal white matter tracts in the SPD subjects, primarily involving areas in the back of the brain, that serve as connections for the auditory, visual, and somatosensory (tactile) systems involved in sensory processing, including their connections between the left and right halves of the brain.

“These are tracts that are emblematic of someone with problems with sensory processing,” said Dr. Mukherjee. “More frontal anterior white matter tracts are typically involved in children with only ADHD or autistic spectrum disorders. The abnormalities we found are focused in a different region of the brain, indicating SPD may be neuroanatomically distinct.”

The researchers discovered a clear parallel between the microstructural abnormalities in the white matter of the posterior cerebral tracts focused on sensory processing and the auditory, multisensory and inattention scores reported by parents in the sensory profile. The strongest correlation was for auditory processing, with other correlations seen for multisensory integration, vision, tactile, and inattention.

The abnormal microstructure of sensory white matter tracts revealed by DTI MRI in kids with SPD in all probability changes the course of sensory transmission so that processing of sensory stimuli and incorporating data across multiple senses becomes problematic or unfeasible. “We are just at the beginning, because people didn’t believe this existed,” stated Dr. Marco. “This is absolutely the first structural imaging comparison of kids with research diagnosed sensory processing disorder and typically developing kids. It shows it is a brain-based disorder and gives us a way to evaluate them in clinic. We are just at the beginning, because people didn’t believe this existed.... [This study] shows it is a brain-based disorder and gives us a way to evaluate them in clinic. Future studies need to be done, she said, to research the many children affected by sensory processing differences who have a known genetic disorder or brain injury related to prematurity.”

The study’s findings were published July 9, 2013, in the open access online journal NeuroImage:Clinical.


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University of California, San Francisco Benioff Children’s Hospital