Question:

Is Pandas/PANS Autoimmune Encephalitis?

Answer:

To answer this question, as there is a great deal of confusion around this question, IAES reached out to one of the most world renowned researchers in the Pandas/PANS field, Dr. Jennifer Frankovich of Stanford.  Here is her complete answer.

There is a lot of confusion in the Pandas/PANS field (as there is in the medical field in general!)., Dr. Frankovich stated. Pandas/PANS is not Autoimmune Encephalitis (AE), but is a differential diagnosis to AE. 

Here is a list of inflammatory brain conditions that can present with neuropsychiatric symptoms:

CNS vasculitis

Multiple sclerosis & related conditions

Neuropsychiatric Lupus

Neuro Behcets

Basal ganglia encephalitis

Sydenham Chorea

PANS

Autoimmune Encephalitis  (AE)

Many inflammatory diseases have overlapping features.  In this vein, PANS is more like multiple sclerosis in that it is relapsing and remitting and is triggered by an infection with regards to the first deterioration.  However, PANS involves complement and other systemic inflammatory features (small vessel inflammation, arthritis, etc) like lupus.  PANS also has clinical features which overlap with  Sydenham chorea and basal ganglia encephalitis (see these articles basal ganglia involvement, see MRI and Sleep article).

 Personally, I think PANS has less overlap with Autoimmune Encephalitis than the other inflammatory brain conditions.

All the above inflammatory brain conditions have features of autoimmunity, including PANS (see article by Pittenger).  But having evidence of autoimmunity does not define the disease.  Most inflammatory diseases are complex and involve many arms of the immune system.  Although there is evidence for autoimmunity in PANS, this is only one feature, and the other mechanisms needs to be addressed (both in pursuing research, designing clinical trials, and treating individual patients).

 Not all patients should undergo lumbar puncture (LP), EEG, MRI.  Just as in Sydenham Chorea, sometimes the clinical features are so obvious that doing an LP is not justified and may be traumatizing without clear benefit.  For example, a child with abrupt-onset OCD and meets criteria for PANS at age 5 who goes into remission in the classic time frame (3 months) and has 2 other episodes which fully resolve before coming to our clinic in their 4^th episode, and never progresses to develop seizures or other neuro signs, should not get an LP.  His clinical coarse is classic for PANS and nothing at all like Autoimmune Encephalitis! 

Of the 450 pre-screened) patients we have evaluated, 220 met strict PANS criteria, ~30 had a severe presentation and underwent full Autoimmune Encephalitis work-up, and only 1 met Autoimmune Encephalitis criteria.  So AE among those who present with a PANS-like presentation is exceedingly rare and I am so glad we did not do an LP on all 450!!!

 Currently, (July 2022), we are in the process of writing a review article that I hope will clarify this for the field. 

 What is tragic, is that despite all the data which supports PANS as involving inflammation, (which is actually more data than what exists for sero-negative AE), these families (and their clinicians) have tremendous difficulty getting treatments covered by insurance. This is why many families and clinicians will call it AE… because it is (in their mind) the closest diagnostic match that will get insurance to approve treatments.  

 Note from IAES: If you have received a treatment denial, please review our ‘How to avoid or appeal a treatment denial’ page. The most common diagnostic code used for Pandas/PANS when a clinician is using an AE diagnostic code to get treatment for their patient is G04.90. Research that includes dose and frequency is available/downloadable on this page.

Written by:

Jennifer Frankovich, MD, MS

Clinical  Professor | Pediatrics – Allergy, Immunology, Rheumatology

Co-Director, Stanford Children’s Immune Behavioral Health Clinic

Director, Stanford Immune Behavioral Health Research Program

Stanford University School of Medicine

700 Welch Rd, Suite 301, MC: 5896 | Palo Alto, CA 94304

July-5-2022

References (linked above):

Association of Pediatric Acute-Onset Neuropsychiatric Syndrome With Microstructural Differences in Brain Regions Detected via Diffusion-Weighted Magnetic Resonance Imaging

Association of Pediatric Acute-Onset Neuropsychiatric Syndrome With Microstructural Differences in Brain Regions Detected via Diffusion-Weighted Magnetic Resonance Imaging

Autoimmune Basal Ganglia Disorders

Autoimmune Basal Ganglia DisordersAntibodies From Children With PANDAS Bind Specifically to Striatal Cholinergic Interneurons and Alter Their Activity