Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS)

Excerpt

The inclusion of a chapter on pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (or PANDAS) is essential to provide a history of the disease and provide current information about its association with Streptococcus pyogenes (group A streptococci), tics, obsessive compulsive disorder (OCD) and its relationship to Sydenham chorea (SC), which is the neurologic manifestation of acute rheumatic fever. PANDAS has been misunderstood and confusing to doctors since its discovery, but the original group of the first 50 cases as described by Dr Susan Swedo (Swedo, et al., 1998) has a similarity to Sydenham chorea that distinguishes this initial group from tic and OCD cases. As this chapter will examine, the acute onset is an important feature of these disorders, as are their piano-playing choreiform movements, enuresis, night-time fears, separation anxiety, learning regression, and handwriting disabilities.

The most current literature, which has been recently published in the Journal of Child and Adolescent Psychopharmacology (Murphy, et al., 2015b; Murphy, Parker-Athill, Lewin, Storch, & Mutch, 2015a; Toufexis, et al., 2015; Gerardi, Casadonte, Patel, & Murphy, 2015; Chang, et al., 2015), provides new insight into the clinical phenotype of PANDAS; namely, a subgroup of pediatric acute-onset neuropsychiatric syndrome (PANS), which has been proposed to have multiple etiologies, including those that are genetic and immunologic, and that present either with or without preceding infections, such as with Streptococcus pyogenes (Toufexis, et al., 2015). PANS is a subtype of obsessive compulsive disorder (OCD) that presents with an abrupt onset or exacerbation of neuropsychiatric symptoms (Murphy, et al., 2015b), including moderate or severe OCD. Elevated anti-streptococcal antibody titers tended to have higher OCD severity and the symptoms tended to lead to sudden and severe impairment, due to comorbidities, such as anxiety, behavioral regression, depression, and suicidality. Comorbid tics in PANS were associated with decline in school performance, visuomotor impairment, eating disorders, deterioration of handwriting skills, and lower quality of life, as compared to children without tics (Murphy, et al., 2015b). In addition, clinical evaluation of youth with PANS and PANDAS and recommendations for diagnosis were reported from the 2013 PANS conference held at Stanford University where a group of clinicians and researchers who were academicians with clinical and research interest in PANDAS and PANS (Chang, et al., 2015). PANDAS is clearly a subtype of PANS (Murphy, et al., 2015b; Murphy, Parker-Athill, Lewin, Storch, & Mutch, 2015a; Chang, et al., 2015) and not all PANS cases have an underlying streptococcal infection—but all PANDAS cases are associated with streptococcal infections, at least temporally.

When these diseases appear, treatment with antibiotics can be successful, and a treatment trial of cefdinir by Murphy and colleagues indicated that therapy with cefdinir, a β lactam antibiotic, provided notable improvements in tic symptoms rated by the Yale Global Tic Severity Scale (YGTSS) and OCD symptoms rated by the Children’s Yale-Brown Obsessive Compulsive Scale (CY-BOCS). However, the differences within the groups as a whole were not significant. β-lactam antibiotics have been proposed to be neuroprotective above and beyond their antibiotic efficacy (Murphy, Parker-Athill, Lewin, Storch, & Mutch, 2015a). Anti-neuronal autoantibodies against the brain in SC and PANDAS react with brain antigens including dopamine receptors (Cox, et al., 2013; Brimberg, et al., 2012), lysoganglioside (Kirvan, Swedo, Heuser, & Cunningham, 2003; Kirvan, Swedo, Snider, & Cunningham, 2006a), and tubulin (Kirvan, Cox, Swedo, & Cunningham, 2007), as well as the activation of the calcium calmodulin-dependent protein kinase II (CaM KII) in human neuronal cells (Kirvan, Swedo, Heuser, & Cunningham, 2003). Human anti-brain antibodies expressed in Tg mice targeted dopaminergic neurons and signaled the dopamine D2 receptor (D2R) (Cox, et al., 2013). Evidence strongly suggests that human anti-brain autoantibodies induced by Streptococcus pyogenes infections target the dopamine receptors (Cox, et al., 2013; Brimberg, et al., 2012) and that animal models immunized with the S. pyogenes antigen develop obsessive behaviors and movement problems, along with antibodies that react with the dopamine receptors and signal the CaMKII, similar to antibodies found in humans with SC and PANDAS (Brimberg, et al., 2012; Lotan, et al., 2014a).