Sensory Processing Disorder, or SPD, is not technically an autism spectrum disorder -- making it difficult to address on an IEP -- but many children with autism also have some symptoms of SPD, which is why I'm writing about it under the "Autism Awareness" heading.

One of the things we learn early on in school is that we all have five senses: taste, touch, smell, hearing, and sight. But as Hartley Steiner, author of This is Gabriel Making Sense of School, points out on her blog, Hartley's Life with 3 Boys, there are actually seven. In addition to the five we learn about as kids (sight, sound, taste, touch, and smell) there are two more -- vestibular and proprioceptive. And those are the ones that pose a particular problem for some kids who have SPD and are on the autism spectrum.

Those last two senses have to do with balance and coordination. The vestibular sense helps you establish equilibrium -- it's located in your inner ear, and if you've ever had motion sickness, you've experienced your vestibular sense at work. The proprioceptive sense, which is sometimes lumped in with kinesthetics, involves your central nervous system's ability to coordinate and communicate between parts of your body.

In a neurotypical person, signals from all seven senses are organized and translated into certain motor or behavioral responses. In kids with SPD, however, they don't. Neuroscientist Dr. Jean Ayres compared SPD to a neurological "traffic jam," with sensory singals unable to reach the parts of the brain that interpret them correctly.  According to the SPD Foundation, "A person with SPD finds it difficult to process and act upon information received through the senses, which creates challenges in performing countless everyday tasks. Motor clumsiness, behavioral problems, anxiety, depression, school failure, and other impacts may result if the disorder is not treated effectively."

There's a tendency to dismiss kids with SPD as being clumsy or "just being difficult," especially in school, where people are still focused on those first five senses. When you have a kid with SPD or autism, as Steiner points out, "You spend equal amounts of time convincing others that your child is not OK as you do that he is OK"

But with a good occupational therapist and a regular "sensory diet," change is possible. "Parents need to remember that their sensational child?s needs will change from one day to the next and so will the tools, exercises and activities that their body's need to calm down or get going," writes Cynna T. Laird in a guest post at Mom-blog.com. The author of Not Just Spirited: A Mom's Sensational Journey With Sensory Processing Disorder (SPD) and I'm Not Weird, I Have SPD, Laird points out that "Some children will live with SPD all of their lives while some with milder forms of SPD 'out grow' their sensitivities. But all of these children learn to ‘reconnect’ their brains to process sensory information effectively through specific treatment with a trained occupational therapist."

The successes can be stunning. My friend Heather's daughter recently learned to ride a bike, a moment of triumph for any child -- but even moreso for a kid with SPD.

Lylah M. Alphonse is a Globe staff member and mom and stepmom to five kids. She writes about juggling career and parenthood at The 36-Hour Day and blogs at Write. Edit. Repeat. E-mail her at lalphonse@globe.com. April is Autism Awareness Month; you can read her posts about autism here.