31.3 Intellectual Disability
1133
with intellectual disability than in the general population; how-
ever, these findings do not elucidate specific diagnoses.
Neuroimaging
Neuroimaging studies with populations of intellectually dis-
abled patients using either computerized tomography (CT) or
Figure 31.3-1
A.
young child with Down syndrome.
B.
A young adult with fragile X syndrome. (Courtesy of L.S. Syzmanski, M.D., and A.C. Crocker, M.D.)
Figure 31.3-2
A 6-year-old girl with Hurler’s syndrome. Her care has involved a
class for seriously multihandicapped children, attention to cardiac
problems, and special counseling for patients. (Courtesy of L.S.
Syzmanski, M.D., and A.C. Crocker, M.D.)
Figure 31.3-3
Two brothers, age 6 and 8 years, with Hunter’s syndrome, shown
with their normal older sister. They have had significant devel-
opmental delay, trouble with recurrent respiratory infection, and
behavioral abnormalities. (Courtesy of L.S. Syzmanski, M.D., and
A.C. Crocker, M.D.)
magnetic resonance imaging (MRI) have found high rates of
abnormalities in those patients with microcephaly, significant
delay, cerebral palsy, and profound disability. Among patients
with intellectual disability, neuroimaging is indicated, accom-
panying findings that suggest seizures, microcephaly or macro-
cephaly, loss of previously acquired skills, or neurologic signs
such as dystonia, spasticity, or altered reflexes.
Although clinically not diagnostic, neuroimaging studies are
currently also utilized to gather data that may eventually uncover
biological mechanisms contributing to intellectual disability.
Structural MRI, functional MRI (fMRI), and diffusion tensor
imaging (DTI) are utilized in current research. For example,
current data suggest that individuals with fragile X syndrome
