5) Association with streptococcal infection.
At initial onset, the symptoms may have followed an asymptomatic (and therefore untreated) streptococcal infection by several months or longer, so the inciting strep infection may have gone unnoticed. However, on subsequent infection recurrences, the worsening of the neuropsychiatric symptoms may be the first sign of an occult (“hidden”) strep infection. Prompt treatment of the strep infection is often effective in reducing the OCD and other neuropsychiatric symptoms.
Strep throat infections can only be diagnosed by obtaining a throat culture that yields Group A beta-hemolytic streptococcal bacteria. In order to have a reliable throat culture, the swab must reach the oropharynx (the top back part of the throat) which typically is slightly uncomfortable and makes the child gag. A throat culture swab that only touches the back of the tongue will give a falsely negative result, as will one that is just touched to the sides of the throat. Poorly done throat cultures are a common cause of false negative results. Rapid strep tests can also give falsely negative results, as they miss about 10-15% of cases of strep throat. If the rapid strep test is negative, an overnight culture should be done to make sure that there aren’t strep bacteria present.
Anti-streptococcal titers can also be used to diagnose a strep throat, but require that two separate blood tests are done several weeks apart and timed just right to show a “rising titer.” Strep infections trigger the production of anti-streptococcal antibodies, which are measured by the titers. When the child is initially infected with the strep bacteria, his titers will be low, but should increase over the next 4-6 weeks as more anti-streptococcal antibodies are produced. If the child’s blood is tested too late, the titers may already be elevated, but it won’t be possible to know if these “high titers” are related to the current difficulties, or if they’re left over from a previous strep infection, since titers can remain elevated for several months or longer. Thus, a single “high anti-streptococcal antibody titer” isn’t sufficient to prove that a strep infection was the trigger for the child’s symptoms.
Recognizing and Diagnosing Pediatric Acute-onset Neuropsychiatric Syndrome (PANS)
Because it is often difficult to demonstrate the relationship between strep infections and OCD/tic symptoms in PANDAS, clinicians and researchers met at NIH in July 2010 to discuss changes to the diagnostic criteria that would facilitate more rapid diagnosis and treatment of affected children. The meeting participants agreed that attention should be focused on the unique features of the children’s clinical presentation, rather than on the role that strep infections might play. To accomplish this goal, the PANDAS criteria were modified to describe PANS – Pediatric Acute-onset Neuropsychiatric Syndrome. PANS encompasses the whole group of acute-onset cases of OCD while PANDAS describes those cases of PANS that have a documented association with streptococcal infections. PANS and PANDAS are comparable to cancer and leukemia (respectively) as PANS is the large class of disorders and PANDAS is one specific type. The diagnosis of PANS is made entirely on the basis of the history and physical examination.
The diagnostic criteria for PANS are as follows:
1) Abrupt, dramatic onset of obsessive-compulsive disorder or severely restricted food intake
2) Concurrent presence of additional neuropsychiatric symptoms, with similarly severe and acute onset, from at least two of the following seven categories:
- Anxiety (particularly, separation anxiety)
- Emotional liability (extreme mood swings) and/or depression
- Irritability, aggression and/or severely oppositional behaviors
- Behavioral (developmental) regression (talking baby talk, throwing temper tantrums, etc.)
- Deterioration in school performance
- Sensory or motor abnormalities
- Somatic signs and symptoms, including sleep disturbances, bedwetting or increased urinary frequency.
3) Symptoms are not better explained by a known neurologic or medical disorder, such as Sydenham chorea, systemic lupus erythematosus, Tourette disorder, or others.
NOTE: The diagnostic work-up of patients suspected of PANS must be comprehensive enough to rule out these and other relevant disorders. The nature of the co-occurring symptoms will dictate the necessary assessments, which might include MRI scan, lumbar puncture or electroencephalogram (EEG) in some cases. More often, laboratory studies will be warranted and should include tests to determine if there is a current infection or ongoing immunologic dysfunction.