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Clinical Description and Applied Aspectsby Michael A. Roman, PhD
IntroductionThe syndrome of nonverbal learning disabilities (NVLD) includes a number of specific, potentially debilitating symptoms. Rourke (1995a) has grouped these into three major areas: neuropsychological deficits, academic deficits, and social-emotional/adaptational deficits. Neuropsychological deficits include difficulties with tactile and visual perception, psychomotor coordination, tactile and visual attention, nonverbal memory, reasoning, executive functions, and specific aspects of speech and language. Deficits in math calculations, mathematical reasoning, reading comprehension, specific aspects of written language, and handwriting are primary academic concerns. Social deficits include problems with social perception and social interaction. Children with this disorder are also seen as having substantially increased risk for internalized forms of psychopathology, primarily anxiety and depression. There has also been evidence to suggest a greater risk for suicide (Rourke, Young, & Leenaars, 1989). The NVLD syndrome has been described as a distinct diagnostic entity only recently. The foremost researcher in the area is Byron Rourke, although many other individuals have been intimately involved with investigating and treating this disorder (e.g., Fletcher et al., 1992; Johnson & Myklebust, 1967). Perhaps the first written descriptions of the syndrome were prepared by Johnson and Myklebust, although there is no reason to believe the disorder is new. Nonverbal learning disabilities represent a discrete and separate diagnostic entity. However, some of the symptoms identified are similar to those described for other disorders. Individuals with right hemisphere dysfunction (Semrud-Clikeman & Hynd, 1990; Weintraub & Mesulam, 1983), Asperger's syndrome (Klin, Sparrow, Volkmar, Cicchetti, & Rourke, 1995; Semrud-Clikeman & Hynd, 1990; Wing, 1981), and "central processing disorders" (Rourke, 1982) each possess a number of symptoms that overlap with those seen in NVLD. Nevertheless, these disorders can be differentiated through proper assessment. For example, right hemisphere dysfunction may produce a number of specific deficits not seen in the typical NVLD presentation (Ardila & Ostrosky-Solis, 1984). These may include more severe speech prosody deficits, more pronounced deficits with planning and organization, and more severe tactile-spatial deficits. Separate theoretical developmental models have emerged that emphasize the role of the right cerebral hemisphere (Goldberg & Costa, 1981) versus the role of subcortical white matter systems (Rourke, 1987) to explain deficits common to both conditions. Overall, however, these models may be more complementary rather than contradictory in that they both yield accurate predictions regarding deficits under somewhat different circumstances (Rourke, 1995a). Some clinicians have also suggested that Asperger's syndrome and NVLD are similar disorders. This is a controversial assertion. Many researchers have questioned the validity of Asperger's syndrome as a distinct diagnostic entity apart from autism (Semrud-Clikeman & Hynd, 1990; Wing, 1991). In essence, the lower functioning children diagnosed with Asperger's may be more properly diagnosed as autistic. In turn, many of the higher functioning children diagnosed with Asperger's syndrome may instead be children with NVLD who have been misdiagnosed. While the NVLD syndrome has only recently been described in detail (Rourke, 1987, 1989), a number of important articles and two major books have been dedicated to descriptions of the disorder (Rourke, 1989, 1995a). Despite this fact, the syndrome is unfamiliar to many psychologists, diagnosticians, and educators. There is no formal provision under federal special education law recognizing the existence of nonverbal learning disability as a handicapping condition. In most cases, children with this disorder are best classified as Other Health Impaired. Because they may also have specific motor skills deficits, problems with math, social interactional difficulties, and/or emotional disturbances, some of these children may also be appropriately classified as orthopedically handicapped, learning disabled, or emotionally disturbed. This may be particularly appropriate for cases of neurologically acquired NVLD rather than the more common developmental cases of the disorder.
The purpose of this article is to familiarize the reader
with the NVLD syndrome and the current state of research on this disorder.
Practical guidelines for identifying children at risk, evaluating and
diagnosing the syndrome, and making treatment recommendations are emphasized.
Finally, a case example with accompanying test data illustrations is provided.
Such children are often described as better "auditory learners" than "visual learners." This is related to their greater proficiency with verbal-auditory modalities than tactile-visual modalities (Rourke, 1995a). In addition, they are frequently described as less active and more reluctant to physically explore their environment (Rourke, 1989). This lack of active exploration is believed to be secondary to their lack of proficiency with tactile and visual input (Rourke, 1995a). In effect, because they frequently gain little useful information from manipulating their environment, they seldom do so on their own initiative. Rourke (1989) provided the first detailed description of the nonverbal learning disability syndrome based on his research into learning disability subtypes (Rourke & Fisk, 1988). More recently (Rourke, 1995a), refined and expanded his description of NVLD symptoms. His model is dynamic in speculating that primary neuropsychological deficits lead to secondary deficits in modality-specific aspects of attention and, more generally, in the extent to which children actively explore their environment. These primary neuropsychological deficits include tactile perception, visual perception, and motor coordination. In turn, these secondary deficits lead to tertiary deficits, particularly in nonverbal memory, abstract reasoning, executive functions, and specific aspects of speech and language. Specific, measurable impairments in academic performance, social functioning, and emotional well-being are direct by-products of this constellation of primary, secondary, and tertiary neuropsychological deficits.
Rourke (1995a) also described a number of assets in
children with NVLD. These abilities typically measure within the average to
above average range relative to normal peers. These strengths include simple
motor skills, auditory perception, simple auditory attention, and rote memory
for simple verbal material. Language strengths include adequate receptive
language, adequate simple verbal expression, and good phonetic analysis. The
relative strengths with phonetic analysis demonstrated by children with NVLD
frequently lead to good single word recognition and strong spelling skills,
particularly for phonetically predictable words. However, they often have
difficulty with spelling and decoding phonetically unpredictable sight words.
"Cognitive," as used in this context, refers to an individual's abilities rather than to specific acquired skills. This distinction between abilities and skills is an important one. When a cognitive deficit is present, it is reasonable to expect that all skills dependent on that cognitive ability will be hindered to at least some degree. Of course, all measures of ability are at least in part related to the measurement of acquired skills (Anastasi, 1988). For example, the concept of intelligence is a completely valid ability-based construct (e.g., Brody & Brody, 1976; Mattarazzo, 1972). However, all intelligence tests rely on the measurement of acquired skills and knowledge to make inferences regarding underlying ability. Nevertheless, when a cognitive deficit is truly present, difficulties should be expected on all measures requiring skills dependent on that particular cognitive ability. This is similar to the distinction between production deficits vs. mediational deficits as described by Flavell (1970).
"Neuropsychological" refers to both simple and
complex cognitive abilities that can be directly or indirectly linked to the
integrity of cerebral functioning. The goal of neuropsychological evaluation
is to investigate discrete cognitive processes involved in acquiring new
information. For example, poor performance on a measure of copying, such as
the Developmental Test of Visual-Motor Integration (Beery, 1982), assuming
adequate effort has been put forth by the test taker, may be due to any of a
number of factors. Problems with visual perception, motor execution, spatial
planning, or the integration of visual and motor abilities may result in poor
copying of geometric figures. It is the goal of a comprehensive
neuropsychological evaluation to attempt to determine which of these factors
are involved. Therefore, neuropsychological does not refer to any specific
test or set of tests, but rather to a way of thinking about and investigating
cognitive functions. In some cases, this may also involve making inferences
about the integrity of cortical or subcortical brain regions that subserve
specific cognitive processes.
Many measures of executive functioning exist. Some of the
more commonly administered measures include the Wisconsin Card Sorting Test
(Berg, 1948), the Category Test (Reitan, 1979), the Tower of London (Shallice,
1982), the Trail Making Test (Reitan, 1979), and the Progressive Figures and
Color Form Tests (Reitan & Wolfson, 1985). In addition, many tests of
attention and working memory could appropriately be considered measures of
executive functioning (Pennington, 1994).
Deficits in executive functions, including working memory, are hypothesized to be responsible for these difficulties on more complex verbal memory measures (Rourke, 1995a). Of course, it is reasonable to expect that NVLD children that do not demonstrate executive functioning deficits will be less likely to show deficits on verbal memory measures. However, weaknesses in nonverbal memory are still likely to be observed.
A good core memory battery for assessing the presence of
nonverbal learning disabilities might include the Verbal Selective Reminding
Test or the California Verbal Learning Test and selected subtests of the Wide
Range Assessment of Memory and Learning, particularly the Story Memory,
Picture Memory, and Design Memory subtests. For many children with this
disorder, discrepancies can also be found between auditory span of attention,
as measured by a digit span test, and spatial span of attention, as measured
by the Finger Windows subtest of the WRAML or Corsi blocks (Milner, 1971). In
addition, many of these children demonstrate a significantly poor backward
digit span with a relatively better forward digit span. The tendency of many
children to mentally "visualize" the forward sequence and then
"read" it backwards frequently exceeds the NVLD child's capacity to
manipulate mental representations.
NVLD children sometimes demonstrate weakness in
particular aspects of speech and language. As with right hemisphere damage
individuals (Ryalls, Joanette, & Feldman, 1987), difficulties with speech
prosody and problems understanding and/or expressing emotional intonation are
frequently observed in the more severe cases of NVLD. Difficulties with
prosody often involve monotone speech with little inflection. Because these
children are often hyperverbal in social contexts, their peers frequently see
them as droning on relentlessly over boring topics. The deficits these
children demonstrate in nonverbal aspects of interaction directly lead to an
overreliance on verbalization as a primary means of social interaction.
Because the content of their speech is often simple and repetitive, they
frequently present as having a restricted range of interests, one of the
primary features of Pervasive Developmental Disorder. Difficulties with
emotional intonation and affective expression in speech can be measured by
asking the child to repeat a neutral phrase within different emotional
contexts. For example, they may be asked to state, "I'm going to the
store," as if they were angry, sad, or surprised. Similarly, their
receptive understanding of the affective tone of language can be assessed by
having the examiner repeat this same neutral phrase with different emotional
inflections, then asking the child to label the corresponding mood.
Problems with drawing or copying are frequently observed. In addition, handwriting may often be poor, at least initially. There is some evidence that children with NVLD are capable of mastering repetitive motor skills with repeated practice over time, despite the fact that they may be particularly weak in acquiring these skills initially. Handwriting, copying of simple shapes, cutting, coloring, pasting, and simple drawing are examples of fine motor skills that frequently improve with age.
One of the better and more dramatic measures for
investigating NVLD is the Tactual Performance Test (Reitan, 1979). This task
requires the subject to place blocks into a formboard while blindfolded. This
measure is arguably the only truly spatial measure in our assessment arsenal
because it is performed without the aid of visual input. Because children with
NVLD have extreme difficulty "building spatial maps," they
frequently perform poorly on this task, often demonstrating little to no
learning (Harnadek & Rourke, 1994).
As noted above, children with NVLD are frequently able to
achieve average or near-average proficiency on a number of repetitive motor
tasks, such as handwriting. They are frequently less coordinated with regard
to gross motor activity, particularly when the development of specific skills
is required. For example, they may not have difficulty riding a bicycle, but
may demonstrate significant difficulty playing competitive sports. In general,
these children are far less athletically capable than their peers.
Because these children frequently have adequate phonological abilities, they may often be more successful at reading and spelling phonetically predictable words than phonetically unpredictable words. This can sometimes result in a failure to find the expected discrepancies between math and reading or math and spelling on integrated tests such as the Wide Range Achievement Test, even when the diagnosis of NVLD is appropriate. Using more sensitive measures, such as the Woodcock-Johnson Tests of Achievement (Woodcock & Johnson, 1989), can frequently assist the examiner in documenting the discrepancy. Children may sometimes demonstrate better performance on the Word Attack subtest then the Word Identification subtest. More sensitive measures of spelling, such as the Test of Written Spelling - 3 (Larsen & Hammill, 1994) often yield notable discrepancies, with higher standard scores obtained for phonetically predictable words than phonetically unpredictable words. Another classic finding is the discrepancy between content areas of academics as opposed to more applied aspects. Content areas can be defined as the more basic and mechanical aspects of an academic subject. These include word recognition and word attack for reading; arithmetic calculations within math; and spelling, grammar, and syntax within written language. In contrast, applied aspects of academic subject areas include reading comprehension, math applications (including word problems and algebra), and written composition.
With regard to NVLD children, reading decoding is
frequently average while reading comprehension is often poor. Math reasoning
is often more impaired than math calculations. They may have difficulty with
word problems and almost always struggle with algebra. Within the area of
written language, spelling, vocabulary usage, and sentence construction may be
adequate. However, children and adults with NVLD frequently have difficulty
generating ideas. B. P. Rourke (personal communication, September, 1991)
indicated that college students with NVLD may often produce lengthy term
papers composed of well constructed sentences that fail to make any
substantive points. In this regard, their writing is often "empty"
and superficial. The same phenomena are also frequently observed in their
pragmatic language, particularly when they are pressed on a specific topic of
conversation. Problems with executive functions, integration and synthesis of
information, and generalization of knowledge are thought to underlie this
content versus applied discrepancy (Rourke, 1995a).
Social judgment and social problem solving are also typically impaired. Some of these impairments are a direct result of problems with perception. In effect, when individuals are unable to accurately perceive a social situation, they are at a significant disadvantage for choosing a correct response. Deficits in reasoning and generalization of knowledge also directly contribute to disadvantages in social problem solving. Furthermore, their behavioral response to similar situations occurring over time may appear very inconsistent and even contradictory. Interpersonal intimacy is frequently impaired, although problems forming close personal attachments may not be noticed until late childhood or early adolescence when dating begins. Rourke (1995a) speculated that these difficulties with establishing intimacy are directly related to the lack of "tactile-perceptual and psychomotor prowess required for smooth affectional encounters" (p. 17). Difficulty maintaining meaningful friendships may also occur. As already noted, problems with speech prosody and expressive language may lead to increased rejection by peers.
Another major characteristic of individuals with NVLD is
a lack of adaptability (Rourke, 1995a). In general, children, adolescents, and
adults with this disorder respond poorly to novel circumstances. The ability
to deal with changing circumstances is a fundamental aspect of social
competency. It is also an important aspect of normal social development. The
difficulties with reasoning, flexibility, and problem solving in NVLD
individuals, combined with their other cognitive deficits, place them at a
substantial disadvantage for coping with the changing circumstances of
day-to-day life.
The lifelong difficulties with academic and social
functioning most NVLD individuals endure contribute directly to their problems
with emotional adjustment. Some of these difficulties with internalizing
emotional problems can be demonstrated in early childhood. However, problems
with anxiety and depression are much more common through adolescence and into
adulthood. Rourke et al. (1989) indicated that the frustrations many
individuals with NVLD face culminate when they attempt to enter the workforce.
They rarely make good impressions during job interviews. They are also more
likely to demonstrate difficulties getting along with coworkers.
Visual-spatial difficulties and problems with reasoning and judgment make them
more accident prone and less successful in many occupations (Rourke et al.,
1989).
As these children develop into later infancy and more advanced motor abilities begin to emerge, they are often poorly coordinated. They may participate only minimally during feeding and play times. Acquisition of simple self-help skills is often delayed. Furthermore, once they begin to walk, they may appear clumsy and are often more likely to bump into things or break objects around the house. As Rourke (1995a) indicated, it is not unusual for these children to be labeled as hyperactive or diagnosed with an Attention Deficit Hyperactivity Disorder during the preschool and kindergarten years. Their poor social judgments can often be interpreted as problems with impulsivity. Furthermore, the poor motor coordination resulting from their tactile and visual-spatial deficits increases the likelihood they will be identified as disruptive or destructive. Difficulties with daily living skills related to eating, dressing, and simple grooming may be noted. In particular, motor abilities necessary for dressing - such as fastening fasteners and learning to tie shoes - are frequently impaired. The acquisition of early preacademic skills related to coloring, cutting, and pasting is also typically delayed. In many cases, these children show little to no interest in working with puzzles, blocks, Legos, or other developmentally appropriate materials. Unfortunately, it is the author's experience that it can be difficult to obtain accurate information regarding a child's proficiency for building puzzles and for working with blocks and other construction materials from parent interviews. Sometimes parents will report that their children demonstrate normal interest and proficiency in these types of tasks even when objective observers would rate them poorly. Generally, parents are more reliable and accurate in reporting levels of proficiency for dressing, cutting, coloring, and pasting. NVLD children frequently demonstrate initial difficulties acquiring early academic skills. Problems with letter and number recognition, difficulty with one-to-one correspondence in counting, and problems with copying letters and numbers are common. Printing and drawing also are frequently poor. With repeated practice, most NVLD children develop normal proficiency with these types of tasks. Rourke (1995a) suggested that these children eventually acquire normal or nearly normal proficiency on these types of tasks regardless of whether or not they receive early physical intervention such as occupational therapy. It is not unusual to find a history of early involvement in occupational therapy and other related services. In the preschool and beginning elementary school years, children with NVLD typically demonstrate difficulty getting math, reading, and writing "off the ground." It is common for them to have difficulty acquiring recognition of letters and numbers because of the inherent visual-spatial aspects involved in early acquisition. With frequent practice, they become more successful at these tasks and eventually profit from the development of the necessary symbol systems required for the early development of reading and math concepts. As already noted,often letter formation and handwriting are initially poor, but typically improve over time. In the early elementary school years, children with NVLD may demonstrate average to above average academic performance. This is sometimes true as early as the first grade, but is frequently seen in the second through fourth grade, particularly for children with more minor forms of the disorder. Of course, those children that are more severely affected may never demonstrate average levels of academic proficiency. Unfortunately, as this more successful group of NVLD children progress into middle school, particularly through the fifth through seventh grades, they often begin to have difficulty maintaining their academic performance. For math in particular, affected individuals rarely exceed a sixth grade equivalent, even as adults (Rourke, 1995a). Difficulties with executive functioning, problem solving, and memory for more complex and meaningful verbal and nonverbal material make it difficult for them to maintain their prior levels of performance (Rourke, 1995a). The author has encountered more than one situation in which school personnel have been reluctant to classify a NVLD child as learning-disabled in their middle school or high school years, despite significant intellectual-achievement discrepancies, because they did not demonstrate early academic deficiencies. As already noted above, phonological awareness and the acquisition of phonics often are strengths for NVLD children. They are typically far more proficient in word recognition and spelling than in math. However, this discrepancy may not be obvious until the fourth or fifth grade, largely because of the simple nature of the math tasks that are presented to them. While they frequently have difficulty rapidly retrieving math facts, particularly with regard to learning the multiplication tables, normal variability between children in the earlier grade school years makes it possible for NVLD children to still score within the average gross range for math at this age. However, Rourke (1995a) indicated that these children rarely exceed a fifth or sixth grade level of proficiency in math. Difficulties with reading comprehension, thinking and reasoning, novel problem solving, and written expression are frequently more obvious as these children progress into the later elementary and middle school years. Frequently, a number of practical deficits emerge, particularly with regard to mathbased survival skills related to time, money, and measurement. These children often have difficulty with the concept of time. This often applies to the calendar as well as the clock. Learning to tell time is almost always difficult, particularly on an analog clock. These children may have difficulties naming the days of the week or months of the year in order, but typically succeed after much practice. Problems with time management and scheduling may persist into adulthood. Their ability to recognize and discriminate coins is often slow to develop. More fundamentally, they have difficulty acquiring money concepts. These difficulties frequently persist into adulthood and are manifest as difficulties with budgeting, balancing a checkbook, making change, and doing comparison shopping. Difficulties with measurement concepts are most obvious on tasks requiring estimation. Children and adults with NVLD are often confused by systems and units of measurement and may make outrageous estimations regarding size, distance, or quantity. They may, for example, describe a basketball player as 20 feet tall, even if given comparative information, such as the height of the basketball rim from the floor. These outrageous estimations are particularly common for younger children who manifest this disorder. Older children and adults with NVLD may manifest problems with cooking and household management. Doubling and halving the size of a recipe are examples of tasks that are particularly difficult for these individuals.
Because of their relatively stronger language-based
abilities, it is not uncommon for higher functioning NVLD individuals to
complete college or even obtain a masters degree. However, their difficulties
with social skills and higher level cognitive abilities frequently lead to
frustration on the job or difficulty finding employment. Problems with
planning and organizational skills can further impair their ability to
function well at home and on the job. Less than satisfactory social
relationships and difficulties with developing intimate relationships, as
already described above, can prove particularly frustrating. For these and
other reasons, symptoms of depression and anxiety are common (Rourke &
Fisk, 1981; Rourke et al., 1989; Weintraub & Mesulam, 1983).
There are also differences between individuals with
developmental NVLD compared to those with neurologically acquired NVLD
disorders. It does appear, however, that the incidence of NVLD has been on the
rise over the past 10 to 15 years (B. P. Rourke, personal communication,
September, 1991). Advances in neonatology have resulted in the survival of
more significantly premature and potentially neurologically compromised
children than ever before. While prematurity itself is not necessarily a risk
factor for later cognitive problems (Siegel, 1983), saving more premature
infants does increase the pool of potentially at-risk children.
A number of conditions affecting white matter areas of
the brain have been found to lead to the NVLD syndrome (Rourke, 1995). Some
examples of neurological disorders leading to white matter deficits and NVLD
symptoms include callosal agenesis (Smith & Rourke, 1995), hydrocephalus
(Fletcher, Brookshire, Bohan, Brandt, & Davidson, 1995), metachromatic
leukodystrophy (Dool, Fuerst, & Rourke, 1995), multiple sclerosis (White
& Krengel, 1995), encephalomyelitis, certain types of traumatic brain
injuries (Ewing-Cobbs, Fletcher, & Levin, 1995), and toxic
encephalopathies (White & Krengel, 1995). There is less direct evidence to
implicate defects in white matter as causal in developmental cases of the
disorder.
The following are some standard cautions used by the author to aid families of NVLD children in monitoring potential areas of future difficulty. A behavioral social skills intervention may be necessary to address inadequate social perception and poor social problem-solving skills. Practical day-to-day activities sometimes require more effort for children and adults with NVLD. These actvities include difficulties with mechanical or fine motor operations (e.g., repairing things, using simple tools, building models or puzzles), or difficulties with common tasks requiring math and nonverbal skills, such as cooking. Compensatory techniques can sometimes be helpful, such as relying on a compass, asking for a list of specific landmarks along travel routes, carefully following recipes and instruction manuals, and making procedural notes during tasks to document the steps already completed. Reading graphs, maps, and charts is often difficult because of the spatial requirements of these tasks. Therefore, asking for written comments to explain graphs, getting verbal directions, or reading figure captions and legends carefully can prove helpful. Similarly, music instruction may be effortful. Reading notes, recognizing tunes, keeping rhythm, and following patterns are tasks that are often quite demanding for people with NVLD. When these problems with music are present, it is important to de-emphasize participation in these types of tasks. It may also be difficult for these individuals to listen to oral presentations and take notes. If this occurs, compensatory techniques such as using a tape recorder during lectures should be considered. Timed tests may not accurately reflect actual knowledge or ability because problems with rapid processing of visual-spatial information and problems with higher level reasoning often make it difficult for individuals with NVLD to perform well when time is a factor. Allowing additional time or completely removing time constraints reduce this problem. Explicit directions, orally administered, may be difficult to follow if the child is unclear how to proceed perceptually. In this sense, the comment, "I see what you mean" may be appropriate; if a child with a nonverbal learning disability cannot mentally "picture" what they have been asked to do, they may fail on the task despite their capability of success. Having a teacher or "peer tutor" check periodically to determine that the individual is proceeding correctly can help. Many practical difficulties can be observed in the classroom. Copying math problems or other assignments from a book or chalkboard, writing lengthy reports, or drawing maps could require too much effort. In general, activities requiring drawing, copying, and writing are often difficult for children and adults with NVLD. It may be necessary to have others assist with these tasks, perhaps by providing teacher outlines or having other students offer copies of their own papers. The ability to solve computational math problems is frequently poor because of misalignment of columns of numbers, poor recall of math facts, or a lack of conceptual understanding. Each type of difficulty may require a different type of intervention, such as using paper with columns, encouraging use of a calculator, or providing examples of proper procedures for solving the problem. Conceptually, math topics related to fractions, decimals, percents, geometry, and trigonometry are typically particularly difficult. In addition, "survival math" concepts involving time, money, and measurement concepts are sometimes poor. Additional tutoring and instruction may be required and physical models and manipulative aids may prove necessary to teach the basic concepts. Some individuals with NVLD have difficulty with creative writing, book reports, essays, and term papers. Because of their stronger verbal abilities, these individuals often write lengthier passages using good vocabulary and well-constructed sentences. Unfortunately, the result is often rambling and "empty," failing to convey anything of substance and sometimes never "getting to the point." Teaching them to create and follow outlines and providing editorial assistance with rough drafts may prove helpful. They often need additional time to complete and revise these writing assignments. In addition to these cautionary examples, it is important to consider the appropriateness of special education. There are no formal criteria defining special education eligibility for children with NVLD. The direction of the discrepancy between Verbal and Performance IQ scores, whereby Performance IQ exceeds Verbal IQ, presents a particular difficulty. When a child demonstrates significantly better performance than verbal abilities, nonverbal measures of intelligence are frequently administered as alternative measures of "potential" (e.g., The Test of Nonverbal Intelligence; Brown, Sherbenou, & Johnsen, 1990). Furthermore, children with visual impairments or upper extremity hemiparesis are routinely evaluated using only the verbal subtests from measures of intelligence to establish their "potential." These "alternate" means for assessing general intelligence are commonly accepted by nearly all school districts. However, many school districts do not recognize the Verbal IQ score in isolation as a means for calculating discrepancy-based eligibility for special education in NVLD children. This persists despite the fact that these children are frequently incapable on visual-spatial measures as visually impaired children are. Also, there are no commercially available verbal intellectual measures for nonverbally disabled children that are analogous to the Test of Nonverbal Intelligence.
Depending on their particular presentation, NVLD children
may be classified as learning-disabled (particularly in the area of math), as
emotionally disturbed due to their social and emotional problems, or as
eligible for occupational therapy because of their motor needs. Simply
classifying NVLD children as learning disabled overlooks the extent of their
true needs. Similarly, classifying them as eligible for special education on
the basis of emotional or social deficits is insufficient to address the
global problems presented by this disorder. A holistic approach to
intervention must address academic deficiencies, motor and sensory needs,
social competency, and emotional well being.
C.K. had consistently performed poorly academically and
had been placed in a self-contained classroom for children with behavior
disorders for the past several years. He had no friends at school or at home
and was frequently picked on by other children. Because of his desire to be
accepted socially, he frequently attempted to imitate the actions of other
delinquent adolescents, particularly gang members. C.K. had been assaulted by
other adolescents on several occasions after flashing gang signs. When
interviewed by the school counselors, it became apparent that he had no idea
what the gestures meant. He stated that he was simply copying some of his
other classmates. Most of his special education teachers described him as a
polite and caring adolescent. He was typically received favorably by adults
outside his immediate family.
Higher level reasoning was characterized by significant perseveration on the Wisconsin Card Sorting Test. Perseveration occurs when an individual repeatedly uses an incorrect problem solving strategy despite feedback that the strategy is wrong. It also frequently signifies an inability to consider or derive alternative solutions or strategies. Sequencing and ability to switch mental sets were also extremely poor on the Trail Making Test, Part A and Part B. Verbal learning and memory was poor on the Selective Reminding Test with erratic performance across learning trials and poor delayed recall for the material. Unexpectedly, C.K. also demonstrated moderate impairment for recall of meaningful paragraph length stories on the Story Memory subtest of the Wide Range Assessment of Memory and Learning. Many children with NVLD perform better on such semantic memory tasks. As expected, nonverbal memory functions were very poor and deteriorated in direct relation to the level of difficulty involved as seen by his poorer performance on the Design Memory subtest compared to the Picture Memory subtest of the WRAML. Receptive vocabulary was low average on the Peabody Picture Vocabulary Test - Revised, consistent with his performance on the Vocabulary subtest of the WISC-III. His poor confrontation naming abilities on the Boston Naming Test and poor expressive fluency on the Controlled Oral Word Association Test reflected the commonly seen deficits in more sophisticated aspects of expressive language that are characteristic of NVLD. The Controlled Oral Word Association Test (Benton & Hamsher, 1989) is a measure that allows the subject 60 seconds to generate a list of words, excluding proper nouns, beginning with a particular letter of the alphabet.
C.K. also demonstrated the hallmark of NVLD, impaired
visual-spatial perception. His ability to copy block designs was also extremely
poor. All aspects of sensory-perceptual and fine motor abilities scored within
the impaired range. However, there was no evidence of poorer left hand versus
right hand performance. Fingertip number writing, a task more dependent on
right hemisphere processing, was much poorer than finger localization, a task
often related to functioning of the angular gyrus in the left hemisphere.
One diagnostic complication was the presence of more language problems than would ideally be seen in this disorder. The fact that most of C. K.'s verbal subtests were at least low average, his Verbal Comprehension Index was technically within the Low Average range, reading and spelling were adequate, and receptive vocabulary was low average, suggest that there is probably not an additional primary language disorder present. However, some NVLD children do demonstrate other cognitive deficits, including severe language disorders. This does not necessarily preclude the diagnosis. However, it must be carefully demonstrated that the pattern is not simply one of global cognitive dysfunction.
Most neuropsychologists agree that at least three signs
of NVLD must be present to make the diagnosis likely. These include a VIQ
greater than PIQ discrepancy, math poorer than reading and spelling, and
evidence of significantly poor social interaction. C. K. had each of these
signs, as well as many additional features of the disorder. There was
substantial reason to believe that many of his psychiatric problems were a
direct result of an undiagnosed NVLD. In addition to a lifetime of difficulty
with learning and socialization, he was dismissed by teachers and his parents
as unwilling to work on his behavior problems. In fact, after his parents and
doctors were informed of the NVLD diagnosis, they were much more supportive of
C. K. and more tolerant of his behavior and learning problems.
NVLD is a complex syndrome. Much work remains to be done to better delineate its etiology, prevalence, and practical consequences. However, the work done to date clearly indicates that this can be a disabling condition with many adverse consequences for practical aspects of daily life. From an educational perspective, revision of the concept of the handicapping condition within special education may prove necessary. As neuropsychology has grown as a discipline of study, we have become more aware of the complexity of human learning and its associated problems. Despite this, our current definitions under special education law frequently place inadequate emphasis on discrete cognitive processes, focusing primarily on academic-achievement discrepancies. In order for children with complex syndromes such as NVLD to be better and more appropriately served, it is essential that educators, clinicians, and administrators become better informed about the contributions of neuropsychology to understanding learning.
References
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