Jenike, Baer, Minichiello: OCD: Practical Management; Mosby,1998:
In children, such symptoms have been called pediatric autoimmune
neuropsychiatric disorders associated with streptococcal infections
(PANDAS) which may arise when antibodies directed against invading
strep bacteria cross-react with basal ganglia structures, resulting
in onset of or exacerbations of obsessive-compulsive or tic
disorders. There is a report (Giedd et al, 1996) of severe worsening
of obsessive-compulsive symptoms in an adolescent boy following
infection with group A beta-hemolytic streptococci for whom serial
magnetic resonance imaging scans of the brain were acquired to assess
the relationship between basal ganglia size, symptom severity, and
treatment with plasmapheresis. OCD symptoms were associated with
acute basal ganglia enlargement. These data provide further support
for basal ganglia-mediated dysfunction in OCD and the potential for
immunological treatments in PANDAS patients.
Why do some patients develop OCD symptoms as a consequence of
streptococcal infections and Sydenham chorea and others do not?
Intriguing recent findings (Murphy et al, 1997) suggest that D8/17, a
B lymphocyte antigen, may serve as a marker for susceptibility to
some forms of childhood-onset OCD and Tourette syndrome, as well as
rheumatic fever or Sydenham's chorea. The average percentage of B
cells expressing the D8/17 antigen was significantly higher in
patients (mean =3D 22%, SD =3D 5%) than in comparison subjects (mean
=3D 9%, SD =3D 2%). When classified categorically, all patients but
only one comparison subject were D8/17 positive. Patients with
childhood-onset obsessive-compulsive disorder or Tourette syndrome
had significantly greater B cell D8/17 expression than comparison
subjects despite the absence of documented Sydenham's chorea or
rheumatic fever.
Along the same research lines, Swedo et al (1997) wanted to further
study whether this trait marker of rheumatic fever susceptibility
(D8/17) could identify children with pediatric autoimmune
neuropsychiatric disorders (OCD and tic disorders) associated with
streptococcal infections (PANDAS). They obtained blood samples from
27 children with PANDAS, nine children with Sydenham's chorea, and 24
healthy children which were evaluated for D8/17 reactivity.
Individuals were defined as D8/17 positive if they had 12% or more
D8/17+ cells. They found that the frequency of D8/17-positive
individuals was significantly higher in both patient groups than it
was among the healthy volunteers: 85% of the children with PANDAS and
89% of the children with Sydenham's chorea, compared with 17% of the
healthy children, were D8/17 positive. Further, the mean number of
D8/17+ cells was similar in the two patient groups and was
significantly higher in these groups than in the group of healthy
children. These results suggest that there may be a subgroup of
D8/17-positive children who present with clinical symptoms of
obsessive-compulsive disorder and Tourette syndrome, rather than
Sydenham's chorea, but who have similar poststreptococcal autoimmunity.
There are treatment implications of these findings. Researchers at
the National Institute of Mental Health (oral communication) reported
that a boy who had tested positive for a strep infection was enrolled
in an experimental study in which he received intravenous
gammaglobulin, a treatment that removes circulating strep antibodies
in the body. Within three weeks, the child's obsessions had lessened,
and within six weeks they had disappeared. So far 17 children -
including the above 5-year-old boy - have been enrolled in a NIMH
treatment trial being conducted the past several years. In a
presentation of the data (American Psychiatric Association meeting,
5/97), Dr. Susan Swedo told psychiatrists that the results were
dramatic. In a double-blind placebo controlled trial, there was
virtually no change in either OCD or tics in those who received a
placebo in an intravenous solution, but there was a 45% decrease in
behavioral symptoms in the majority of those who received gammaglobulin.
