AUTOIMMUNE ENCEPHALITIS, only fully understood in the two thousands*, can cause psychosis, rapid deterioration in memory, and altered behaviour. As a result, people with this disorder can present to psychiatric/mental health services and professionals, sometimes after being declared ‘psychiatric’ by medical services or professionals. The 2012 book and 2016 film ‘Brain on Fire. My month of madness’ recorded Susannah Calahan’s experience of delayed diagnosis and misdiagnosis, but with ultimately successful treatment for autoimmune encephalitis (AE).
AE occurs when antibodies are developed by the sufferer’s body against proteins in their brain. The most common example is anti- NMDAR (N-methyl-D-aspartate receptor) encephalitis.
A recent editorial** was triggered by a study in JAMA Neurology describing 393 patients in the USA among whom 107 (27%) were incorrectly diagnosed as having Autoimmune Encephalitis, sometimes with negative consequences. Clues to misdiagnosis were an insidious rather than acute onset and lack of MRI (brain imaging) findings or lumbar puncture findings suggestive of inflammation. The editorial authors suggest that clinicians should “favor clinical reasoning over antibody results.”
That is, the authors suggest that sometimes too much emphasis is placed on blood tests for auto-antibodies alone (especially if they are ‘overinterpreted or nonspecific positive results’) and not enough attention given to the history, the whole clinical picture, findings or absence of findings on MRI, and the examination of cerebrospinal fluid, which of course requires lumbar puncture.
Although AE is rare, it often responds to treatment and should be kept in mind by clinicians. This study and editorial emphasise the need to consider the whole clinical picture, not just one blood result. It also illustrates the need for both mental health/psychiatric services and general medical services to be alert to the possibility of patients who present at the ‘wrong door’.
Nearly 50 years ago a young doctor published an article about a similar issue of patients with neurosurgical diseases being admitted to psychiatric hospitals***.
* Much earlier ‘paraneoplastic’ neurological conditions (which included SAE) associated with cancers, and lymphomas, were known but not fully understood.
**Dalmau, J. Graus, F., Autoimmune Encephalitis – Misdiagnosis, Misconceptions, and How to Avoid Them JAMA Neurol. 2023;80(1):12-14. doi:10.1001/jamaneurol.2022.4154
** Williams SE, Bell DS, & Gye RS. (1974). Neurosurgical disease encountered in a psychiatric service. Journal of Neurology, Neurosurgery and Psychiatry 37, 112 16.