Anti-NMDA receptor encephalitis | |
---|---|
Other names | NMDA receptor antibody encephalitis, anti-N-methyl-D-aspartate receptor encephalitis, anti-NMDAR encephalitis |
A schematic diagram of the NMDA receptor | |
Specialty | Neurology |
Symptoms | Early: Fever, headache, feeling tired, psychosis, agitated [1] [2] Later: Seizures, decreased breathing, blood pressure and heart rate variability [1] |
Complications | Long term mental or behavioral problems [2] |
Usual onset | Over days to weeks [3] |
Risk factors | Ovarian teratoma, unknown [1] [4] |
Diagnostic method | Specific antibodies in the cerebrospinal fluid [1] |
Differential diagnosis | Viral encephalitis, acute psychosis, neuroleptic malignant syndrome [2] |
Treatment | Immunosuppresive medication, surgery [1] |
Medication | Corticosteroids, intravenous immunoglobulin (IVIG), plasma exchange, azathioprine [2] |
Prognosis | Typically good (with treatment) [1] |
Frequency | Rare [2] |
Deaths | ~4% risk of death [2] |
Anti-NMDA receptor encephalitis is a type of brain inflammation caused by antibodies. [4] Early symptoms may include fever, headache, and feeling tired. [1] [2] This is then typically followed by psychosis which presents with false beliefs (delusions) and seeing or hearing things that others do not see or hear (hallucinations). [1] People are also often agitated or confused. [1] Over time, seizures, decreased breathing, and blood pressure and heart rate variability typically occur. [1] In some cases, patients may develop catatonia. [5]
About half of cases are associated with tumors, most commonly teratomas of the ovaries. [1] [4] Another established trigger is herpesviral encephalitis which is associated with over half of all identified pediatric cases [6] , while the cause in other cases is unclear. [1] [4] [7] The underlying mechanism is autoimmune, with the primary target being the GluN1 subunit of the N-methyl-D-aspartate receptors (NMDAR) in the brain. [1] [8] Diagnosis is typically based on finding specific antibodies in the cerebrospinal fluid. [1] MRI of the brain is often normal. [2] Misdiagnosis is common. [8]
Treatment is typically with immunosuppresive medication and, if a tumor is present, surgery to remove it. [1] With treatment, about 80% of cases have a good outcome. [1] Outcomes are better if treatment is begun earlier. [2] Long-term mental or behavioral problems may remain. [2] About 4% of those affected die from the condition. [2] Recurrence occurs in about 10% of people. [1]
The estimated number of cases of the disease is one in 1.5 million people per year. [9] [7] The condition is relatively common compared to other paraneoplastic disorders. [2] About 80% of those affected are female. [2] It typically occurs in adults younger than 45 years old, but it can occur at any age. [4] [8] The disease was first described by Josep Dalmau in 2007. [1] [10]
Prior to the development of a symptom complex that is specific to anti-NMDA receptor encephalitis, people may experience prodromal symptoms, including headaches, flu-like illness, or symptoms similar to an upper respiratory infection. These symptoms may be present for weeks or months prior to disease onset. [11] Beyond the prodromal symptoms, the disease progresses at varying rates, and patients may present with a variety of neurological symptoms. During the initial stage of the disease, symptoms vary slightly between children and adults. However, behavior changes are a common first symptom within both groups. These changes often include agitation, paranoia, delusions, [12] psychosis, violent behaviors [13] , and suicidal behaviors such as suicidal ideation and self-inflicted violence [14] . Other common manifestations include seizures and bizarre movements, mostly of the lips and mouth, but also including pedaling motions with the legs or hand movements resembling playing a piano [ citation needed ]. Some other symptoms typical during the disease onset include impaired cognition, memory deficits, and speech problems (including aphasia, perseveration or mutism). [15] [16]
The symptoms usually appear psychiatric in nature, which may confound the differential diagnosis. In many cases, this leads to the illness going undiagnosed. [17] As the disease progresses, the symptoms become medically urgent and often include autonomic dysfunction, hypoventilation, cerebellar ataxia, loss of feeling on one side of the body, [18] loss of consciousness, or catatonia. [19] During this acute phase, most patients require treatment in an intensive care unit to stabilize breathing, heart rate, and blood pressure.[ citation needed ] One distinguishing characteristic of anti-NMDA receptor encephalitis is the concurrent presence of many of the above listed symptoms. The majority of patients experience at least four symptoms, with many experiencing six or seven over the course of the disease. [15] [16]
The condition is mediated by autoantibodies that target NMDA receptors in the brain. [20] These can be produced by cross reactivity with NMDA receptors in teratomas, which contain many cell types, including brain cells, and thus present a window in which a breakdown in immunological tolerance can occur. Other autoimmune mechanisms are suspected for patients who do not have tumors. Whilst the exact pathophysiology of the disease is still debated, empirical evaluation of the origin of anti-NMDA receptor antibodies in serum and cerebrospinal fluid leads to the consideration of two possible mechanisms.[ citation needed ]
These mechanisms may be informed by some simple observations. Serum NMDA receptor antibodies are consistently found at higher concentrations than cerebrospinal fluid antibodies, on average ten times higher. [21] [22] This strongly suggests the antibody production is systemic rather than in the brain or cerebrospinal fluid. When concentrations are normalized for total IgG, intrathecal synthesis is detected. This implies that there are more NMDA receptor antibodies in the cerebrospinal fluid than would be predicted given the expected quantities of total IgG.[ citation needed ]
A more sophisticated analysis of the processes involved in antibody presence in the cerebrospinal fluid hints at a combination of these two mechanisms in tandem.[ citation needed ]
Once the antibodies have entered the CSF, they bind to the NR1 subunit of the NMDA receptor. There are three possible methods in which neuronal damage occurs.
First and foremost is a high level of clinical suspicion, especially in young adults showing abnormal behavior as well as autonomic instability. Clinical examination may further reveal delusions and hallucinations, which can aid diagnostic efforts.[ citation needed ]
The initial investigation usually consists of clinical examination, MRI of the brain, an EEG, and a lumbar puncture for CSF analysis. MRI of the brain may show abnormalities in the temporal and frontal lobes, but do so in less than half of cases. A FDG-PET scan of the brain may show abnormalities in cases when the MRI scan is normal. [29] EEG is abnormal in almost 90% of cases and typically shows general or focal slow wave activity. [30] CSF analysis often shows inflammatory changes with increased levels of white blood cells, total protein and the presence of oligoclonal bands. [31] NMDA receptor antibodies can be detected in serum and/or CSF. Whole body FDG-PET is usually performed as a part of tumor screening. Gynecological ultrasound or a pelvic MRI might be performed to search for an ovarian teratoma in women.
Diagnostic criteria for probable and definite anti-NMDA receptor encephalitis have been proposed to facilitate diagnosis at an early stage of the disease and help initiate early treatment. [32]
If a person is found to have a tumor, the long-term prognosis is generally better and the chance of relapse is much lower. This is because the tumor can be removed surgically, thus eradicating the source of autoantibodies. In general, early diagnosis and aggressive treatment is believed to improve patient outcomes, but this remains impossible to know without data from randomized controlled trials. [15] Given that the majority of patients are initially seen by psychiatrists, it is critical that all physicians (especially psychiatrists) consider anti-NMDA receptor encephalitis as a possible cause of acute psychosis in young patients with no past neuropsychiatric history.[ citation needed ]
The recovery process from anti-NMDAR encephalitis can take many months depending on its form and severity. The symptoms may reappear in reverse order: The patient may begin to experience psychosis again, leading many people to falsely believe the patient is not recovering. As the recovery process continues on, the psychosis fades. Lastly, the person's social behavior and executive functions begin to improve. [11] In patients with herpesviral anti-NMDA encephalitis, the recovery process is typically met with poorer long-term outcomes due to extensive lesions caused by viral-indused necrosis in brain tissue [34] .
The estimated number of cases of the disease is 1.5 per million people per year. [7] According to the California Encephalitis Project, the disease has a higher incidence than its individual viral counterparts in patients younger than 30. [35] The largest case series as of 2013 characterized 577 people with anti-NMDA receptor encephalitis. The data were limited, but provides the best approximation of disease distribution. It found that women make up 81% of cases. Disease onset is skewed toward children, with a median age of diagnosis of 21 years. Over a third of cases were children, while only 5% of cases were patients over the age of 45. This same review found that 394 out of 501 patients (79%) had a good outcome by 24 months. [15] 30 people (6%) died, and the rest were left with mild to severe deficits. The study mentioned that of the 38% presenting with tumors, 94% of those presented with ovarian teratomas. Within that subset, African & Asian women were more likely to have a tumor, but this was not relevant to the prevalence of the disease within those racial groups. [15]
Anti-NMDA receptor encephalitis is suspected of being an underlying cause of historical accounts of demonic possession. [36] [37] [38] [39]
New York Post reporter Susannah Cahalan wrote a book titled Brain on Fire: My Month of Madness about her experience with the disease. [37] This has subsequently been turned into a film of the same name. [40]
Dallas Cowboys defensive lineman Amobi Okoye spent 17 months battling anti-NMDA receptor encephalitis. In addition to three months in a medically-induced coma, he experienced a 145-day memory gap and lost 78 pounds. He returned to practice on October 23, 2014. [41]
In the Japanese movie called The 8-Year Engagement , a young Japanese woman ends up being in a coma due to anti-NMDA receptor encephalitis.
Knut, a polar bear at the Berlin Zoological Garden that died on 19 March 2011, was diagnosed with anti-NMDA receptor encephalitis in August 2015. This was the first case discovered in a non-human animal. [42] [43] [44]
In Hannibal , Will Graham was affected by NMDA receptor or antibody encephalitis, also known as anti-NMDAR encephalitis. [45]
The TV series Something's Killing Me featured an episode called "Into Madness" that featured two cases of the disease. [46]
Encephalitis is inflammation of the brain. The severity can be variable with symptoms including reduction or alteration in consciousness, headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.
Serine is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, a carboxyl group, and a side chain consisting of a hydroxymethyl group, classifying it as a polar amino acid. It can be synthesized in the human body under normal physiological circumstances, making it a nonessential amino acid. It is encoded by the codons UCU, UCC, UCA, UCG, AGU and AGC.
The N-methyl-D-aspartatereceptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and predominantly Ca2+ ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA and kainate receptors. Depending on its subunit composition, its ligands are glutamate and glycine (or D-serine). However, the binding of the ligands is typically not sufficient to open the channel as it may be blocked by Mg2+ ions which are only removed when the neuron is sufficiently depolarized. Thus, the channel acts as a "coincidence detector" and only once both of these conditions are met, the channel opens and it allows positively charged ions (cations) to flow through the cell membrane. The NMDA receptor is thought to be very important for controlling synaptic plasticity and mediating learning and memory functions.
Neuromyelitis optica spectrum disorders (NMOSD) are a spectrum of autoimmune diseases characterized by acute inflammation of the optic nerve and the spinal cord (myelitis). Episodes of ON and myelitis can be simultaneous or successive. A relapsing disease course is common, especially in untreated patients.
Rasmussen syndrome or Rasmussen's encephalitis is a rare inflammatory neurological disease, characterized by frequent and severe seizures, loss of motor skills and speech, hemiparesis, encephalitis, and dementia. The illness affects a single cerebral hemisphere and generally occurs in children under the age of 15.
Glutamate receptors are synaptic and non synaptic receptors located primarily on the membranes of neuronal and glial cells. Glutamate is abundant in the human body, but particularly in the nervous system and especially prominent in the human brain where it is the body's most prominent neurotransmitter, the brain's main excitatory neurotransmitter, and also the precursor for GABA, the brain's main inhibitory neurotransmitter. Glutamate receptors are responsible for the glutamate-mediated postsynaptic excitation of neural cells, and are important for neural communication, memory formation, learning, and regulation.
Meningoencephalitis, also known as herpes meningoencephalitis, is a medical condition that simultaneously resembles both meningitis, which is an infection or inflammation of the meninges, and encephalitis, which is an infection or inflammation of the brain tissue.
Inflammatory demyelinating diseases (IDDs), sometimes called Idiopathic (IIDDs) due to the unknown etiology of some of them, are a heterogenous group of demyelinating diseases - conditions that cause damage to myelin, the protective sheath of nerve fibers - that occur against the background of an acute or chronic inflammatory process. IDDs share characteristics with and are often grouped together under Multiple Sclerosis. They are sometimes considered different diseases from Multiple Sclerosis, but considered by others to form a spectrum differing only in terms of chronicity, severity, and clinical course.
NMDA receptor antagonists are a class of drugs that work to antagonize, or inhibit the action of, the N-Methyl-D-aspartate receptor (NMDAR). They are commonly used as anesthetics for humans and animals; the state of anesthesia they induce is referred to as dissociative anesthesia.
Hashimoto's encephalopathy, also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), is a neurological condition characterized by encephalopathy, thyroid autoimmunity, and good clinical response to corticosteroids. It is associated with Hashimoto's thyroiditis, and was first described in 1966. It is sometimes referred to as a neuroendocrine disorder, although the condition's relationship to the endocrine system is widely disputed. It is recognized as a rare disease by the NIH Genetic and Rare Diseases Information Center.
Limbic encephalitis is a form of encephalitis, a disease characterized by inflammation of the brain. Limbic encephalitis is caused by autoimmunity: an abnormal state where the body produces antibodies against itself. Some cases are associated with cancer and some are not. Although the disease is known as "limbic" encephalitis, it is seldom limited to the limbic system and post-mortem studies usually show involvement of other parts of the brain. The disease was first described by Brierley and others in 1960 as a series of three cases. The link to cancer was first noted in 1968 and confirmed by later investigators.
A paraneoplastic syndrome is a syndrome that is the consequence of a tumor in the body. It is specifically due to the production of chemical signaling molecules by tumor cells or by an immune response against the tumor. Unlike a mass effect, it is not due to the local presence of cancer cells.
Anti-glutamate receptor antibodies are autoantibodies detected in serum and/or cerebrospinal fluid samples of a variety of disorders such as encephalitis, epilepsy and ataxia. Clinical and experimental studies starting around the year 2000 suggest that these antibodies are not simply epiphenomena and are involved in autoimmune disease pathogenesis.
Herpes simplex encephalitis (HSE), or simply herpes encephalitis, is encephalitis due to herpes simplex virus. It is estimated to affect at least 1 in 500,000 individuals per year, and some studies suggest an incidence rate of 5.9 cases per 100,000 live births.
Bickerstaff brainstem encephalitis is a rare inflammatory disorder of the central nervous system, first described by Edwin Bickerstaff in 1951. It may also affect the peripheral nervous system, and has features in common with both Miller Fisher syndrome and Guillain–Barré syndrome.
Lymphocytic pleocytosis is an abnormal increase in the amount of lymphocytes in the cerebrospinal fluid (CSF). It is usually considered to be a sign of infection or inflammation within the nervous system, and is encountered in a number of neurological diseases, such as pseudomigraine, Susac's syndrome, and encephalitis. While lymphocytes make up roughly a quarter of all white blood cells (WBC) in the body, they are generally rare in the CSF. Under normal conditions, there are usually less than 5 white blood cells per μL of CSF. In a pleocytic setting, the number of lymphocytes can jump to more than 1,000 cells per μL. Increases in lymphocyte count are often accompanied by an increase in cerebrospinal protein concentrations in addition to pleocytosis of other types of white blood cells.
Autoimmune encephalitis (AIE) is a type of encephalitis, and one of the most common causes of noninfectious encephalitis. It can be triggered by tumors, infections, or it may be cryptogenic. The neurological manifestations can be either acute or subacute and usually develop within six weeks. The clinical manifestations include behavioral and psychiatric symptoms, autonomic disturbances, movement disorders, and seizures.
Anti-VGKC-complex encephalitis are caused by antibodies against the voltage gated potassium channel-complex (VGKC-complex) and are implicated in several autoimmune conditions including limbic encephalitis, epilepsy and neuromyotonia.
Anti-Hu associated encephalitis, also known as Anti-ANNA1 associated encephalitis, is an uncommon form of brain inflammation that is associated with an underlying cancer. It can cause psychiatric symptoms such as depression, anxiety, and hallucinations. It can also produce neurological symptoms such as confusion, memory loss, weakness, sensory loss, pain, seizures, and problems coordinating the movement of the body.
Anti-IgLON5 disease is an uncommon neurological autoimmune condition linked to autoantibodies directed against the IgLON5 protein. Sleep disturbance, bulbar symptoms, and abnormal gait make up the majority of the clinical presentation, which is then followed by cognitive dysfunction. The diagnosis of anti-IgLON5 disease is primarily based on clinical signs and the identification of IgLON5 antibodies in patient serum and/or cerebrospinal fluid.