When her second child was born, Jenna knew something was amiss; even as a baby, Alexa was hard to soothe. Today, she is a 3-year-old picky eater who is easily frustrated and melts down over anything from wearing shoes to taking a bath. Alexa was recently diagnosed with sensory processing disorder.

Formerly called sensory integration dysfunction, SPD occurs when the brain has trouble processing information through the senses. SPD exists on a spectrum, affecting one or more of the senses and usually with a combination of over- and under-sensitivities. It affects up to 16 percent of school-age children in the United States. "SPD is common in children who have autism and attention deficit hyperactivity disorder, but it also affects a surprising number of other young children," says Brian

Udell, MD, who practices behavioral pediatrics in Davie, Fla., and blogs at TheAutismDoctor.com.

Although no two children with SPD are the same — some are sensitive to things like a tag on a shirt or the sound of a vacuum cleaner, while others may be uncoordinated, hard to engage in play or in constant motion — most are picky eaters and orally defensive when dealing with taste, smell, sound and textures of foods.

How do you distinguish between a finicky child and a problem eater? "Eating fewer than 10 foods and really struggling to try new foods is beyond being picky and a red flag for a problem eater," says Denver-based pediatric dietitian Jessica Crandall, RDN. Children with SPD may be obese, underweight or even normal weight, yet most suffer from nutritional deficiencies because of their limited food choices.

"I start with the three-day diet record to determine patterns and uncover nutritional inadequacies," says Crandall. "Food first" is ideal, but supplements are essential to help fill nutritional gaps in many of the limited-variety diets, which typically have low levels of vitamin D, calcium, zinc and iron.

"Eating is the most complicated human behavior there is and involves all areas of human development," says Kay Toomey, PhD, psychologist and clinical director of SOS Feeding Solutions in Denver. "Research shows from birth to 8 years, 20 percent of all kids struggle with feeding challenges."

Many symptoms appear to be ordinary issues — after all, parents struggle daily trying to get picky eaters to eat meals and a wider variety of nutritious foods — but the frequency, intensity and disruption of everyday life may lead parents to seek medical evaluation.

Choose a registered dietitian nutritionist with training and experience for your child's specific needs, suggests sensory science specialist Annette Hottenstein, MS, RD.

Treatment plans are individualized and focus on multisensory activities designed to help children cope where they struggle and get used to food and textures. Exercising patience and persistence without being forceful is key. Structured routines, eating at the same times and locations and with the same utensils can help create comfort and a primer for mealtime. Parents and siblings should serve as role models and praise children for taking a "no-thank-you" bite. Foods served should be easy for kids to manage — cut into small, chewable bites or thin strips to hold. Present a child with a total of three foods on their plate, roughly 1 tablespoon per each year of age for each food. Encourage the child to play with their food and explore it. And getting children into the kitchen so they may participate in meal preparation, setting the table, passing food family-style and cleaning up also can be beneficial.

"Start where they are and advance slowly, because change is hard for these kids," says Sally Hara, MS, RD, owner of ProActive Nutrition, specializing in autism spectrum disorders, adding that it can take up to 20 presentations and a lot of positive reinforcement to get kids to try new foods.

The exact cause of SPD is unknown. One recent study looked at the brain activity of SPD children and found abnormal brain structure showing a biological basis differentiating it from other neurodevelopmental disorders. Another study of twins found that hypersensitivity to light and sound may have a genetic component.

However real it may be for affected parents, SPD is not recognized by the American Academy of Pediatrics. A 2012 policy statement by AAP discourages pediatricians from using SPD as a diagnosis because of insufficient evidence as an independent disorder. And last year, SPD was not included in the Diagnostic and Statistical Manual of Mental Disorders, 5th Ed. (AAP 2013).

When a condition is not recognized, research funding and insurance coverage are harder to come by. Children in school are eligible for early intervention assessment, which may offer school-based services; however, Toomey suggests getting a complete evaluation from a medical team consisting of an occupational therapist, speech therapist, registered dietitian nutritionist, developmental pediatrician and a psychologist.