Autoimmune Encephalitis: A neurological challenge masked by psychiatric symptoms

December 5, 2023 

By Dr Ellie Kok Huey Tean, Consultant Neurologist and Internal Medicine Physician, Sunway Medical Centre Velocity (SMCV)  

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Imagine a neurological disease that mimics what it feels like to inexplicably lose your mind. One day, you are a healthy adult whose biggest concern is completing your projects at work. And the next day, you start having hallucinations and delusions.
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In the realm of frequently misdiagnosed conditions, the relatively recent discovery of Autoimmune Encephalitis (AE), with almost two decades of history, stands out. Defined as a group of related conditions where the body's immune system attacks the brain, AE manifests in progressive or relapsing-remitting forms, presenting various subtypes. And if left untreated, this condition can lead to permanent brain injury and, in severe cases, even death.
 
AE is a spectrum of disease that affects a person’s cognitive function which can lead to a disruption in judgment.

More often than not, its diagnosis is often hindered or delayed as its clinical symptoms mimic psychiatric conditions. AE is often misdiagnosed when a patient is presented with psychiatric symptoms such as hallucination, paranoid thoughts, delusion, behavioural and personality changes. Thus sometimes, it can be confused with a psychiatric disorder.
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AE, stemming from self-generated antibodies in the body, exhibits its presence across various age groups without demonstrating a hereditary link. The manifestations of AE encompass an array of symptoms, including headache, personality and behavioural changes, cognitive function decline, seizures, movement disorders, and hallucination or delusion.
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The causes of AE are diverse, spanning from the exposure to specific viruses such as herpes simplex virus, and the presence of certain cancers. Research indicates that AE predominantly impacts individuals from their early teenage years to age 50, with women being more susceptible than men.

Autoimmune Encephalitis across age groups
While AE may manifest in individuals of any age, specific phenotypes within AE may exhibit a higher prevalence in certain age or gender groups. For example, N-methyl-D-aspartate receptor (NMDAR) encephalitis tend to be more commonly observed in adolescents and young adults.

Moreover, within this specific phenotype, there is an elevated susceptibility observed in young women, particularly individuals with an underlying tumour, specifically Gonodal Teratoma – tumours situated in the reproductive organs. An instance of this is Ovarian Teratoma, a serious and potentially fatal condition that occurs in young women, predominantly affecting brain cells.

For the elderly population, a distinct AE phenotype, known as paraneoplastic encephalitis, arises when an elderly person have an occult (hidden) cancer. This abnormal cancer cell can trigger the immune system to generate specific antibodies that attack the brain, causing AE symptoms way before the manifestation of cancer. 

When neuropsychiatric manifestation occur in elderly patients, neurologists can identify the cancer tumour through imaging tests. Most commonly, tumors originate from the lungs, while in female patients, they can be from the ovary or breast. Thus, early treatment seeking and detection significantly enhance the chances of complete patient recovery.
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Family members or caretakers of the elderly should be vigilant for AE symptoms, especially given the elderly's susceptibility to infections – a primary cause of AE. It is also crucial to monitor for symptoms such as memory decline, behavioural changes, seizures, and gait problems, such as loss of balance while walking.

Diagnostic and treatment process
Doctors and consultants would need to follow specific criteria to diagnose AE, including differentiating between psychiatric conditions and neurological diseases. This involves assessing short-term memory loss, psychiatric symptoms, or other altered mental states within a three-month timeframe. Additional indicators include movement disorders, and seizures. For assisting in diagnosing this condition, specific tests would be electroencephalogram (EEG), cerebrospinal fluid analysis and a brain MRI. 

It is wise to seek a neurologist’s opinion once a person presents with acute onset manifestation of psychiatric problems. Once the diagnosis is confirmed and with appropriate Immunotherapy treatment, most patients can be cured from AE. The treatment for AE is targeted to eliminate the auto-antibody that is detected in the body, and the usual Immunotherapy treatment deployed comprises IVIG, plasma exchange and immunosuppression agents.

However, there is a minority of people who may relapse within five years – therefore making follow-ups crucial to prevent or detect any such re-occurrence in the body. 

In times of health uncertainties, prioritising professional medical advice is paramount, and symptoms should never be taken lightly. Whether it's AE or any other nerurological condition, early intervention remains the cornerstone of effective treatment. For individuals experiencing symptoms indicative of AE, prompt consultation with healthcare professionals is crucial for accurate diagnosis and timely treatment.

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