Nonverbal Learning Disabilities and Sensory Processing Disorders

In our presentation at the 2006 annual meeting of the American Academy of Child and Adolescent Psychiatry, we suggested that child psychiatrists who come across a child with the profile of the following hypothetical case should consider whether the child may have deficits that are not currently covered by DSM-IV nosology: either a nonverbal learning disability (NVLD) or a sensory processing disorder (SPD).

Case Vignette

David is an 11-year-old boy with a history of attention-deficit/hyperactivity disorder (ADHD) and a learning disability in mathematics. He has been treated with stimulants and atomoxetine. With medication he has an improved attention span and decreased motor activity, yet both his teachers and his parents note some significant behavioral problems that they attribute to ADHD. David is not oppositional but has a tendency to be inflexible once routines are established and can get into conflicts if changes occur. He will lash out impulsively if someone bumps into him, followed by sincere remorse. He is slow to pick up on social cues but is not distant from others. For example, he interrupts the conversations of others and seems surprised by the negative response from those he interrupts. He prefers larger clothes and fidgets if collars and sleeves are "too tight."

Considering whether a child may have an NVLD or SPD is a "road less traveled" for many behavioral professionals. These disorders may be best thought of as a group of developmentally based higher cortical problems, often in the nondominant hemisphere, that affect a number of functional systems but have no basis in spoken or written language.

Nonverbal learning disabilities

A number of NVLDs have been separately recognized over the years, including disorders of motor control (dyspraxia), visual-spatial processing, mathematics (dyscalculia), music (amusia), memory, executive function, and socioemotional cognition and behavior. Conceptually, these disorders have areas of commonality but are defined primarily by the single symptom of concern. Nevertheless, they all appear to have defects in emotional recognition and expression, social interaction, spatial concepts, prosody (the variation in vocal pitch and rhythm that conveys shades of meaning), and attention.

Because of these common threads, a number of authors have defined a broad-based disorder that involves deficits in executive self-regulation and integrating spatial relationships based in the prefrontal and frontal cortex of the nondominant hemisphere. Therefore, many terms for these disorders may be found in the literature, including NVLD,^1,2 right hemisphere deficit,^3-5 and developmental socioemotional processing disorder.⁶

Prefrontal dysfunction

Prefrontal dysfunction results in impairment of executive cortical functions that are used to direct behavior toward a goal and to sustain that behavior over time. Prefrontal dysfunction also inhibits the ability to screen out distractions. While not officially recognized as a learning disability, the Interagency Committee on Learning Disabilities acknowledged the importance of these functions in modifying or amplifying impairments in other cognitive areas. Clinically, the impairment of executive function is increasingly recognized as a disorder that can be diagnosed and treated with intervention strategies.^7,8

Frontal lobe executive function

Frontal lobe executive function is divided into 3 specific areas that have general neuroanatomic correlates. The dorsolateral circuit has broad neuroanatomic connections from a large area of the lateral cortex and is the most important for executive function. It subserves cognitive regulation necessary for working memory, organization, planning, problem solving, environmental monitoring, self-awareness, attention, mental flexibility, and abstract reasoning. This circuit specifically controls initiative and initiation, disinhibition, and shifting of cognitive activity.

Behavioral regulation is controlled through the orbitofrontal cortex with deep connections to the basal ganglia complex. Behavioral regulation involves initiation of behavioral responses, inhibition of automatic responses, and delay of immediate gratification (impulse control), sustaining of behavioral and motor response, and anticipation of future consequences.

Finally, the medial cortex through the anterior cingulate circuit with links to the limbic system is responsible for emotional regulation; it modulates emotional arousal, expression of mood, and self-soothing strategies. All of these functions impact internal emotional processes and how they are expressed in a social and environmental context. Behavior may be repetitive and obsessive because of an inability to modify the behavior to fit different social contexts. Conversely, children may be overly dependent on immediate social or environmental cues to guide their behavior and may act based on these cues without reflecting on the appropriateness of their action in a broader social context.

Executive functions show gradual maturation into adolescence, especially attention and response inhibition. NVLDs have greater significance as the child ages and increased function in these systems, particularly the dorsolateral circuit, is expected. Executive processing deficits suggesting NVLD have been found in some children with ADHD as well as in children with conduct disorder and episodic dyscontrol involving both emotion and aggression. These children with NVLD often show a more complex behavioral and cognitive disorder than is expected in children with typical ADHD.

While children with NVLD may be inattentive in most areas, there may be problems in some areas with over- focused or compulsive behavior suggestive of obsessive-compulsive disorder. These children often have problems with transitions and, thus, prioritizing; they are impulsive, moody, and impatient without a clear ability to prioritize or organize. In some situations they are underaroused even as they appear to be restless and talkative. Careful behavioral history and clinical observations of patterns of behavior suggesting an NVLD are often more important for making the initial diagnosis than performing neuropsychological tests, which can determine the full range and degree of executive deficits.^9,10

The right hemisphere

The right hemisphere subserves a variety of complex and often interrelated functions. It is dominant for attention and orientation. It is critical for visual-spatial perception and analysis as well as for integrating that information into cognitive processes and learning. Language pragmatics and prosodics are governed by a major right-sided network that is as broadly represented and as complex as the better-known language systems of the dominant hemisphere. Lastly, the right hemisphere is critical for environmental interaction, because it modulates the social and emotional responses to external stimuli. These functions may be affected in isolation, but more often impairment exists in varying combinations that produce complex and, at times, puzzling social, behavioral, and learning profiles.

Impact of NVLD on children

Children with NVLD have an impaired ability to read facial, gestural, and prosodic cues in language, as well as having parallel deficits in expression, with reduced gestures, flat facial affect, and monotonous prosody. These children often misread social cues and misinterpret social situations. They have great difficulty in navigating new situations and may apply previous experience in a rote but inappropriate fashion. This often results in difficult interpersonal relationships and a tendency to withdraw socially.

The typical child with NVLD has a psychoeducational profile characterized by a verbal IQ that exceeds the performance IQ with coding and block design subtests often significantly lowered. Reading achievement exceeds mathematics achievement but in time it becomes apparent that rote reading is much better than comprehension and abstract inference.

Language is usually significantly involved in NVLD. Pragmatics (such as maintaining eye contact while talking) and prosodics are often poor in these children. Singing or following melodies are equally impaired. These children often fail to grasp verbal humor and usually are reduced to engaging in practical jokes, often inappropriate, and sometimes with disastrous social results.¹¹ Rote language is good but complex language is often deficient.

From poor neuromotor integration to frank apraxia, these children often display a spectrum of neurological findings detectable through a careful neuromotor examination for lateralized deficits, particularly when evoking more subtle signs. The Neurological Examination for Subtle Signs¹² describes a system for a structured clinical neuromotor examination that can be quantified for research purposes. Evoking any laterality (especially for motor integration) can indicate a potential for an underlying neurointegrative deficit that reveals the potential neurological basis of a child's defects.

Interventions for NVLD

The ability to define that a child has an NVLD can give all who work with the child a common conceptual basis for intervention. The treatment for these children is often complex and multifaceted. Environmental modification and behavior management, including metacognitive strategies such as social stories,¹³ are techniques that have the greatest success in NVLD. Emphasizing strengths and developing reasonable bypass strategies are critical to the success of any program. For example, helping the child understand the linguistic context of poor prosody and the way it negatively impacts classroom relationships can open new avenues for interaction that may be more purely verbal. Finding physicians who know how to evaluate youth for NVLD and subsequently guide interventions may be difficult. Some academic child psychiatrists and pediatric neurologists may have expertise in this area, as may some academic clinical psychologists. The clinical psychologist may need to ask peers where they have successfully been able to refer patients in the area.

Pharmacological response in NVLD is variable and not well studied. The use of a-adrenergic antagonists, tricyclic anticonvulsants(such as carbamazepine), and the second-generation antipsychotics may be more effective than psychostimulants.¹⁴ Nevertheless, the precise behavioral targets for each of these agents have not been well defined. Any treatment strategy must clearly identify the neurobehavioral component that is the target for this intervention (eg, impulsivity) before treatment is begun. Integration with other behavioral strategies is a must.¹³

Sensory processing disorders

Sensory processing is the interpretation and organization of sensory input. It enables the child to form a response. Sensory information can be external (tactile, visual, auditory, olfactory, gustatory) or internal (vestibular, proprioceptive, interoceptive). The sophisticated structures of the sensory organs, neural pathways, and cortical organization provide an extensive amount of information on the quality, intensity, and location of the stimulus. The reticular system, right hemisphere, and limbic system provide additional prioritization and associations and also assign meaning and affective qualities.

In addition to the reception of sensory input, simultaneous information must be integrated. Competing cues are modulated and must be discriminated from each other. Some of this process is conscious, but most is not. The results have an effect on the patient whether or not he or she is aware of it. Efficiency of sensory processing can enhance a multitude of functional skills. Abnormalities in sensory processing can cause a spectrum of deficits, ranging from insignificant eccentricity to devastating dysfunction.

Many people have problems with sensory processing; often, these are fairly insignificant. However, if abnormalities cause distress and dysfunction, one is considered to have SPD. Certain patterns of pathological sensory processing have been described.^15-17 Symptoms in children with SPDs may appear to be very inconsistent, fluctuating hour-to-hour, or even combining overresponsivity in one area with underresponsivity in another. Electrodermal testing can confirm poor regulation of the autonomic nervous system as at least one contributing factor.^18,19

It is estimated that 5% to 15% of the general population has some type of SPD severe enough to warrant intervention.¹⁶ Postulated risk factors include family history of SPD, perinatal complication, institutionalization,²⁰ and physical or sexual abuse. The incidence is increased in children with autistic spectrum disorders (78%), ADHD (40% to 60%), and a number of other disorders.¹⁶

Sensory discrimination disorder

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.

Sensory-based motor disorders

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 disorders

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

Interventions for SPD

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.

IMPLICATIONS FOR CHILD PSYCHIATRY

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.

References:

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