Nonverbal Learning Disabilities and Sensory Processing Disorders

Sensory discrimination is the ability to distinguish between sensory signals. A child with sensory discrimination disorder may have various difficulties, such as not being able to hear what is said to him if there is background noise, not being able to feel a pencil among the objects in his desk, or not being able to discern whether he is in motion.

Motor disorders often have a sensory basis. The vestibular system provides information on balance and the position of the body in space, especially with regard to gravitational pull. The proprioceptive system provides information about the relational positions of different parts of the body, for example, how different muscle groups need to work together. There are 2 subtypes of sensory-based motor disorders.

The child with dyspraxia will have difficulty in planning and grading motor activities. He may drool, appear clumsy, or avoid daily activities that involve multiple steps. The child with postural disorder may slump at his school desk or appear to be tired.

Sensory modulation is the ability to match behaviors to the intensity of the stimuli. There are currently 3 subtypes of sensory modulation disorders. A child with sensory overresponsivity may be irritated by loud noises or by the way tags in clothing feel. A child with sensory underresponsivity may not hear his name being called or may not realize that he needs to use the toilet. The child who has sensory seeking/craving may like to jump, talk loudly, or mouth objects. Studies suggest that 27% of children who have sensory modulation disorder will present with multiple subtypes.¹⁶

Although SPD was first described in the 1970s,^21-23 management has mainly remained within the domain of occupational therapy, where it is considered to be a subspecialty and requires certification. Occupational therapists (OTs) perform a range of diagnostic testing, including a combination of questionnaires and functional evaluation. Standardized tools exist, including the Sensory Integration and Praxis Test, the Developmental Test of Visual Motor Integration, and the Peabody Developmental Motor Scales. In addition, a variety of other tests are available that address different ages and stages of development. Integrating clinical observation (especially bilateral integration, right-left discrimination, and large movements) with standardized tests is helpful in customizing the evaluation for each presenting individual.

OTs customize treatment in a "child initiated/therapist guided" fashion. Various forms of treatment, including the use of weighted equipment, deep brushing, and suspended activities, are considered to be beneficial, especially in younger children who still exhibit a good deal of brain plasticity. In addition, OTs provide detailed suggestions for modification of the environment to meet the needs of the child. Not only does this increase the child's functional capacity, but it also decreases the inadvertent initiation of the fight-or-flight response when the child is stressed.

NVLD and SPD may coexist with or mimic many other neuropsychiatric disorders, and they may affect the practice of child psychiatry in many ways. Problematic behavior is one of the most common reasons for referral to a child psychiatrist,²⁴ and unrecognized symptoms of NVLD and SPD may exacerbate these behaviors. NVLD and SPD may also complicate diagnosis and treatment. For example, a child who is physically restless and disruptive with executive function problems broader than those of inattention or hyperactivity/impulsivity may have ADHD, SPD, NVLD, or any combination of these. Consequently, treatment may include medication, sensorimotor integration therapy by an OT, or structured prosocial skill training programs. In children with NVLD or SPD and ADHD, standard pharmacotherapy may seem to fail; the children may have difficulty interacting with psychotherapists, may be rejected from educational programs, or may be at risk for legal involvement. Insight is often impaired.

In an effort to place the patient with a disability in self-regulation into a diagnostic category, the child with NVLD or SPD may be given a diagnosis of bipolar disorder, disruptive behavior disorder, intermittent explosive disorder, pervasive developmental disorder, or Asperger disorder. NVLD or SPD should be considered in children with a mathematics learning disability in combination with these unusual learning or social profiles.

While currently it is possible to have a diagnosis of both NVLD and SPD, questions exist about whether NVLD and SPD are truly separate diagnostic entities or are differing conceptualizations by researchers in various fields of a common set of neurobehavioral findings. Because the topic seldom surfaces in the child psychiatric literature, questions also exist as to whether some symptoms usually attributed to attention-deficit and disruptive behavior disorders might be better classified as being part of NVLD or SPD.

Similarly, evaluations of the efficacy for many of the interventions for NVLD and SPD in psychiatric populations await empirical validation. Interventions for these disorders have been developed and evaluated largely by educational psychologists, OTs, and pediatric neurologists whose nomenclatures do not easily translate to the patient populations typically covered in the child psychiatric literature. Consequently, there is a great need for child psychiatrists to collaborate with individuals from these fields to expand the research in this area.

By engaging in research to refine and validate diagnostic criteria for NVLD and SPD and taking part in multidis- ciplinary studies to empirically test potential interventions, child psychiatrists have a tremendous opportunity to assist their patients. Diagnoses can be better defined and treatment teams and plans more appropriately customized. Successes with self-regulation will readily transfer to everyday life experiences and children with these disorders will be more successful.

Dr Dobbins is an assistant professor of pediatrics and psychiatry; Dr Sunder is a professor of neurology, pediatrics, and psychiatry; and Dr Soltys is a professor and chair of psychiatry at Southern Illinois University School of Medicine in Springfield. They report no conflicts of interest concerning the subject matter of this article.