Tuesday, February 2, 2016

The history of lithium therapy


At a meeting of the Psychopharmacologic Drugs Advisory Committee of the Food and Drug Administration (FDA) in the early 1970s, opinion was divided on the use of lithium for “the prevention of recurrent mania.” Gerald Klerman, professor of psychiatry at Harvard, was strongly in favor. But the FDA believed the indication ill justified because of a lack of studies.
Klerman complained at another forum about the bureaucrats’ obduracy. He said he had objected to them that the literature wasn’t always perfect. “What about the first physician who used [lithium] and therefore couldn’t call upon a reasonably good body of evidence in the literature …?” he asked them.
John Jennings (from the FDA): “He’s like the man who ate the first oyster” ().
The history of lithium is a little bit like that of the man who ate the first oyster. Lithium has been in medical use—including psychiatric use—for many years (). Many mineral springs contain lithium, among other elements, and some of them, such as Mineral Wells in Texas, have age-old reputations as “crazy waters” (). In 1847, London internist Alfred Baring Garrod discovered uric acid in the blood of gouty patients. Garrod made the lithium treatment of gout—including “brain gout” —widely known in his 1859 work, The Nature and Treatment of Gout and Rheumatic Gout, and subsequent editions (). Amdi Amdisen and F. N. Johnson have recently reviewed lithium’s early history (, ). By the 1930s, a number of lithium-containing products were on the market, mostly indicated for the control of renal calculi and the “uric acid diathesis.” For example, in 1939, the German pharmaceutical index, The Red List (Die Rote Liste), featured “Lithosanol Bauer,” a combination product of lithium citrate and several other components for kidney, bladder, and gallstones (, ).
In an early psychiatric reference to lithium in 1870, Philadelphia neurologist Silas Weir Mitchell recommended lithium bromide as an anticonvulsant and a hypnotic (). Mitchell later came out for the bromides, preferably lithium bromide, for “general nervousness” (). In 1871, William Hammond, professor of Diseases of the Mind and Nervous System at the Bellevue Hospital Medical College in New York, became the first physician to prescribe lithium for mania: “Latterly I have used the bromide of lithium in cases of acute mania, and have more reason to be satisfied with it than with any other medicine calculated to diminish the amount of blood in the cerebral vessels, and to calm any nervous excitement that may be present” ().
It was, however, Denmark that became the flagship land in using lithium for the treatment and prophylaxis of depression. In 1894, Danish psychiatrist Frederik Lange made explicit reference to lithium in the treatment of melancholic depression, ultimately treating 35 patients with lithium carbonate (12; see reference to F. Lange). (Frederik’s older brother Carl, Professor of Pathology in Copenhagen, is often associated with the introduction of lithium in Denmark in the mid-1880s, yet Carl wrote little about it).
This early Danish literature was then forgotten. In the first half of the 20th century there are virtually no references to lithium in the psychiatric literature, although a tradition of lithium treatment does seems to have persisted. French physician Roger Reyss-Brion recalled that a preparation called “Dr. Gustin’s Lithium” had been popular in the south of France; “It’s quite simply for that reason that you don’t have a lot of manic-depressives in Marseilles” ().
The modern revival of lithium began in 1949 in the Bundoora Repatriation Hospital, a veterans’ hospital in a suburb of Melbourne, Australia, when John Cade, aware of Garrod’s success in using lithium a century previously in the treatment of gout, hypothesized that some condition involving uric acid might lie behind his manic patients’ “psychotic excitement”; Cade began treating 10 of them with lithium citrate and lithium carbonate. Some responded remarkably well, becoming essentially normal and capable of discharge after years of illness (). Unfortunately, 1949 was precisely the wrong time for such an article to appear—after a recent failed experiment with lithium chloride as a substitute for sodium chloride in patients with congestive heart failure ()—and moreover, in such a then-obscure journal. Cade’s discovery was significant not just because it added an important new agent to the psychopharmacologic armamentarium but because it illustrated the triumph of the scientific method, at a time when psychiatry was in danger of losing sight of science. As Cade’s son Jack, himself an intensive-care specialist in Melbourne, and Sydney psychiatry professor Gin Malhi noted in 2007: “John Cade’s discovery demonstrates the importance of clinical observation, the significance of reporting case findings, the value of being patient centered and the scientific benefit of an open and inquiring mind” ().
The Cade article did not go entirely unnoticed, prompting isolated studies of lithium. In 1951, C. H. Noack at the Mont Park Mental Hospital in Melbourne and E. M. Trautner in the Department of Physiology at the University of Melbourne found in an open trial of over 100 patients that the therapeutic benefits outweighed the side effects, judging lithium “very beneficial” for mania (). In France in 1951, two physicians at the Saint-Albain mental hospital administered lithium citrate to ten patients with “chronic mania,” concluding, “The use of lithium in the manic phases of manic-depressive psychoses seems particularly effective” (). Yet the echo was faint.
The breakthrough in lithium treatment for mania and the prophylaxis of manic-depressive illness began in 1952, when Erik Strömgren, head of the Aarhus University psychiatric clinic in Risskov, Denmark—who had read the Cade article—suggested to a staff psychiatrist at the hospital, Mogens Schou, that he might undertake a randomly controlled trial of lithium in mania. Random controls were just being introduced in psychiatric drug trials in those years. Schou randomized the mania patients with a flip of a coin to lithium or placebo, and in 1954 he published the results in a British journal. Schou concluded, “The lithium therapy appears to offer a useful alternative [to electroconvulsive therapy (ECT)] since many patients can be kept in a normal state by administration of a maintenance dose” ().
The Schou article had a large impact and awakened the possibility of lithium treatment for an illness that previously had been governed mainly with barbiturates (but was in fact highly responsive to ECT, introduced in 1938). A number of important international trials occurred, ably reviewed by F. Neil Johnson in hisHistory of Lithium Therapy ().
Yet lithium was tricky to administer, and blood levels a matter of guesswork. The introduction of the Coleman flame photometer in 1958 () changed the situation, making it possible to ascertain more precisely than with the old Beckman photometer how much lithium a patient actually had on board. This opened the way for lithium’s widespread therapeutic use in clinical medicine.
In the international history of lithium, the United States was more or less the last in, first out, in the sense that “the United States is one of the few countries—perhaps the only one—where other drugs, such as valproate and antidepressants, are given to bipolar patients much more often than lithium” (personal communication, anonymous referee). At a time when lithium was firmly established elsewhere, in the United States interest in lithium only began to build in the 1960s. The seminal event was probably Samuel Gershon’s arrival in 1960 at the Schizophrenia and Psycho-pharmacology Joint Research Project of the University of Michigan at the mental hospital in Ypsilanti, Michigan. Gershon, familiar with lithium from working with a group at the University of Melbourne that included Edward M. Trautner, Douglas Coats, and Everton R. Trethewie, introduced lithium to the hospital. In a program financed by Jonathan Cole at the National Institute of Mental Health (NIMH) and directed by Ralph W. Gerard, the investigators at Ypsilanti bought lithium by the kilo from a chemical supply store, then had the local pharmacy put it into capsules. In 1960, Gershon and Arthur Yuwiler, also at Ypsilanti, brought out the first North American publication on lithium (). [Actually, they tied with Edward Kingstone, a resident of Ewen Cameron’s at the Allan Memorial Institute in Montreal, for that honor ()]. It was evidently Gershon’s Michigan experiences that caused the Rowell Laboratories in Minnesota to acquire an early interest in commercializing lithium (). In 1963, Gershon moved to the University of Missouri in St. Louis, then to New York Medical School, where he became prominent among American investigators of lithium.
In 1962, George Winokur introduced lithium to Washington University in St. Louis, having the Barnes Hospital pharmacy make up the pills and achieving an “amazing remission” in a patient who had failed on chlorpromazine treatment and 18 sessions of convulsive therapy. “After that experience,” recalled Paula Clayton, “lithium was the mainstay in the treatment of mania at Barnes Hospital” ().
Following the leadership of Gershon, in the 1960s numerous investigators began lithium studies: Nathan Kline at Rockland State Hospital in New York, Stanley Platman in Buffalo, Paul Blachly in Portland, and Eugene Ziskind in Los Angeles (). A number of these were supported by the NIMH. Ronald Fieve began in the mid-1960s to make the New York State Psychiatric Institute an epicenter of research in lithium, and published in 1966 an influential open-label study ().
As well, a number of controlled lithium trials in mania contributed to assuaging the doubts of the few naysayers, mainly from the Maudsley Hospital. In 1963, Ronald Maggs, at Hellingly Hospital in Hailsham, Sussex, organized the first controlled trial of lithium versus placebo, concluding, “The drug is found to be of value during the acute manic illness” (). Under the leadership of William Bunney and Frederick Goodwin, the NIMH became actively involved in lithium studies in the mid-1960s. In 1966, at the fourth World Congress of Psychiatry, Bunney reported a double-blind study of two manic patients treated with lithium (). By 1969, the study had grown to 30 patients with depression and mania: “Therapeutic results in mania were dramatic,” the investigators said (). In 1971, in a double-blind study led by Peter Stokes and the Psychobiology Study Unit at the Payne Whitney Clinic of New York Hospital–Cornell University Medical College, lithium “demonstrated a significant advantage … over placebo in mania” (). In these four controlled studies of 116 patients, the average response rate was 78% (), an impressive plus for lithium in mania.
By the late 1960s, a kind of “lithium underground” had formed in the United States, many physicians prescribing it without bothering to seek “INDs,” or a permit to use an investigational new drug from the FDA (). Meanwhile, lithium had long become registered elsewhere: lithium gluconate in 1961 in France, lithium carbonate in 1966 in the United Kingdom, lithium acetate in 1967 in Germany, and lithium glutamate in 1970 in Italy (, ). Surely it was now time for the FDA to act? (And in fact when, later in 1970, the FDA did approve lithium, the United States became the 50th country to do so.) At the FDA, it was Merle Gibson, director of the Neuropharmacology Division, who finally overcame internal agency apprehensions and pushed for approval of lithium for acute mania. It is possible that this decision was also motivated by Paul Blachly’s public declaration that he would prescribe it even without FDA approval (). Gibson is said to have held back the Rowell company’s lithium New Drug Application to give Smith Kline and Pfizer a chance to bring their own products to market (J. O. Cole, telephone interview, 17 July 2002).
How about lithium in the prophylaxis of depression, as opposed to the treatment of mania? Even today, the FDA does not accept an indication for lithium prophylaxis in depression (though it accepted, in 1975, the lithium prophylaxis of mania). Yet considerable evidence speaks on behalf of lithium maintenance in depression.
The idea of lithium maintenance originated with Schou at the time of his 1954 study. He had a bipolar patient that, “When we gave him continuous lithium treatment to keep away the highs, we saw that also the lows disappeared. … However, at the time we did not pay much attention to this observation.” Then in 1959, Geoffrey P. Hartigan in England and Poul Baastrup in Denmark independently wrote Schou to ask “whether long-term lithium treatment might perhaps keep away also depressive recurrences, because this was what they had seen in a dozen patients” (36, see p. 265). That was the beginning of several open-label trials in the 1960s. The study that Baastrup and Schou conducted in 1967 of 88 patients at Glostrup Psychiatric Hospital who had been admitted between 1960 and 1966—known as “a medical landmark” —did show lithium’s ability to reduce the frequency of hospitalization in depression (). Three years later, in 1970, Schou and Jules Angst in Zurich, using Angst’s model of bipolar disorder, demonstrated that lithium had in fact a preventive effect in mood disorders (), that, in Per Bech’s terms, it was “not simply for maintenance” ().
Fieve conducted the first controlled trial of lithium in acute endogenous depression in 1968, finding “only a weak to mild antidepressant effect” (). But how about prophylaxis in long-term depressive illness? In 1970, Baastrup and Schou led a placebo-controlled discontinuance study of 84 patients with manic-depressive and endogenous depressive illness. “During the whole trial, which lasted five months, twenty-one placebo patients relapsed and none of the lithium patients” ().
In 1971, Alec Coppen at West Park Hospital in Epsom, together with collaborators at three other mental hospitals, randomly assigned 65 patients with “recurrent affective disorders” to lithium or placebo: “Patients receiving lithium had very significantly less affective illness than patients receiving placebo tablets. No patient on lithium required convulsive treatment while almost half of the placebo group did” (). Coppen later described the results of this study as “absolutely staggering.” “After that we decided to set up a lithium clinic because this obviously was a service we should offer our patients.” Later, Coppen followed up a group of such patients, using as a measure the number of deaths by suicide, “Instead of having a suicide rate of seven per thousand, which is the norm, we had a suicide rate of less than one per thousand” (43, see pp. 272–273).
This round of studies in the early 1970s provided convincing evidence of lithium’s efficacy in preventing relapse in depressive illness. The subsequent literature, ably reviewed in Goodwin and Jamison, will not be considered here (). In a meta-analysis in 1999, Davis et al. concluded that relapse rates on placebo average 74%, on lithium, 29% ().
In retrospect, “the miracle of lithium was not its treatment of acute mania,” as Dennis Charney at Yale University put it at a 1995 meeting of the Psychopharmacologic Drugs Advisory Committee of the FDA. “Neuroleptics, and even high-dose benzodiazepines, are quite effective for the treatment of acute mania. … The issue is prevention of relapse” (). Indeed, this is the issue, and the mystery is why the FDA has not accepted the prophylaxis of depressive disorder—“bipolar illness,” if one will—as an indication.
With the exception of ECT, lithium is the single most effective treatment in psychiatry. Its side effects are easily manageable, and many patients stay on low-dose lithium for decades. Its benefits, in terms of the relief of mania and the prophylaxis of depression, are incalculable. In assessing the history of lithium, therefore, two questions present themselves:
First, why a small group from the Maudsley Hospital in the 1960s could, in an almost malicious manner, have sown scholarly confusion about the true effectiveness of lithium. Aubrey Lewis, professor of psychiatry and head of the Maudsley, considered lithium treatment “dangerous nonsense” (). Lewis’s colleague at the Maudsley, Michael Shepherd, one of the pioneers of British psychopharmacology, agreed that lithium was a dubious choice. In his 1968 monograph, Clinical Psychopharmacology, Shepherd said that lithium was toxic in mania and that claims of efficacy for it in preventing depression rested on “dubious scientific methodology” (). Shepherd also scorned “prophylactic lithium” in an article with Barry Blackwell (). Moreover, Shepherd was publicly contemptuous of Schou. He told interviewer David Healy that Schou had put his own brother on it, and that Schou was such a “believer” in lithium that he seemed to think “really there ought to be a national policy in which everybody could get lithium” (50, see p. 249). [In a separate interview with Healy, Schou confirmed that the family member was his brother (36, see p. 267)]. Lewis and Shepherd were major figures in the field, and their poorly grounded objections to lithium doubtless steered many practitioners away from a beneficial agent. [Years later, when questioned about this mad campaign against lithium, Shepherd said that English psychiatry did not distinguish between psychogenic and endogenous depression, and if lithium were accepted, “all doctors in England would use it against all types of depression, with the result that many patients not in need of it would only suffer damage from it—therefore lithium must be ravaged with fire and sword” ()].
Second, the lithium story raises the question: why in psychopharmacology, scientific evidence—in this case about lithium—often has difficulty in prevailing over commercial messages that run counter to established knowledge (). When Abbott gained FDA approval to market valproate (Depakote) for mania in 1995, a great shift toward the “mood stabilizers” and away from lithium commenced. As David Healy points out, the use of valproate off-label for mania had been growing in the late 1980s, and it was in 1995 that Columbia University closed its lithium clinic. Increasingly, trainees from psychiatry training programs became untutored in lithium use, and would be uncomfortable about prescribing it in practice (). Is lithium about to be eclipsed by less effective but widely advertised mood stabilizers? We cannot definitively answer the question at this time. But it becomes increasingly insistent.

Acknowledgments


Monday, February 1, 2016

Teratoma: NDMA

Anti-NMDA-receptor encephalitis: case series and analysis of the effects of antibodies

Introduction

NMDA receptors are ligand-gated cation channels with crucial roles in synaptic transmission and plasticity. The receptors are heteromers of NR1 subunits that bind glycine and NR2 (A, B, C, or D) subunits that bind glutamate. NR1 and NR2 combine to form receptor subtypes with distinct pharmacological properties, localisation, and ability to interact with intracellular messengers. Overactivity of NMDA receptors causing excitotoxicity is a proposed underlying mechanism for epilepsy, dementia, and stroke, whereas low activity produces symptoms of schizophrenia.
We recently identified a disorder, designated anti-NMDA-receptor encephalitis, that associates with antibodies against NR1–NR2 heteromers and results in a characteristic neuropsychiatric syndrome. The first patients identified were young women with ovarian teratoma who presented with psychosis or memory problems, rapidly progressing to multiple neurological deficits requiring prolonged intensive care support. Despite the severity of the disorder, patients often recovered after tumour removal and immunotherapy, suggesting an immune-mediated pathogenesis. Preliminary studies suggested the target epitopes were located in extracellular regions of NR1–NR2B NMDA receptors. However, selective disruption of receptors containing NR2B, which are predominantly expressed in the forebrain and hippocampus, would not explain the extensive deficits of patients. We postulated that the crucial epitopes were present in the more widely expressed NR1 subunit. If the antibodies were pathogenic we reasoned that their effects on NMDA receptors would be reversible because most patients recover.
We report the clinical features of 100 patients, analysing the frequency and type of tumour association, antibody titres, and response to treatment. We also investigate the epitopic region of the NMDA receptor and how antibodies affect NMDA receptors in primary cultures of hippocampal neurons.

Methods

Patients and procedures

Clinical information was obtained by the authors or provided by referring physicians, and has been partly reported for 21 patients. The webappendix contains additional information and details of control individuals. Control samples were obtained from 20 healthy individuals and 230 patients with suspected autoimmune or paraneoplastic encephalitis, or patients with tumours without encephalitis examined during the period of this study. Samples were from patients seen at University of Pennsylvania or patients referred to the university for a study of autoimmune disorders. All patients had brain MRI, radiological screening for a systemic neoplasm, and serological or CSF studies that ruled out other disorders (webappendix). Serum and CSF were tested for antibodies against the NMDA receptor, and considered positive if three immunohistochemical criteria were fulfilled (figure 1). Antibody titres were measured with ELISA on HEK293 cell lysates ectopically expressing NR1 or NR1–NR2B heteromers (webappendix). Studies were approved by the University of Pennsylvania Institutional Review Board.
Figure 1
Immunohistochemical criteria for the presence of NR1–NR2B antibodies
Neurological outcome was assessed with the modified Rankin scale (MRS) and mini-mental state examination (MMSE). Patients were described as having full recovery if they returned to their jobs (MRS 0, MMSE 29–30); mild deficits, if they returned to most activities of daily living and remained stable for at least 2 months (MRS 1–2; MMSE >25–28); and severe deficits for all other cases.
HEK293 cells transfected with rodent (or human) NR1 or NR2 (A, B, C, or D), or co-transfected with plasmids expressing NR1 and NR2 in equimolar ratios were fixed in 4% paraformaldehyde, permeabilised with 0.3% Triton X-100 and co-incubated with patients’ sera (diluted 1:200 [0.5%]) or CSF (1:10 [10%]) along with a rabbit monoclonal antibody against NR1 (1:10 000, AB9864 Chemicon, Temecula, CA, USA) or rabbit polyclonal antibodies against NR2A (1:200, Upstate, Lake Placid, NY), NR2B (1:200, Zymed, San Francisco, CA) or NR2C (1:200, Chemicon), followed by the appropriate fluorescent secondary antibodies.
To determine the location of the main epitope region, we took advantage of the property of NR1 to stably assemble homomers, and of a modified NR1 subunit (NR1d4), in which amino-acid residues 25–380 are deleted but which still assembles with NR2B (webappendix). The reactivity of patients’ sera with these heteromers (NR1d4–NR2B) was examined by immunocytochemistry as described above.
Embryonic rat hippocampal neurons were cultured as previously described. To determine the degree of immunolabelling of NMDA receptors by patients’ antibodies, rat hippocampal neurons after 14 days in vitro were incubated with patients’ CSF (1:15 dilution in 0.25% Triton X-100) and a rabbit monoclonal antibody against NR1 (1:1000, Chemicon) for 2 h at room temperature followed by the appropriate fluorescent-conjugated secondary antibodies (Jackson Immunologicals, West Grove, PA, USA). Imaging and quantification was done as previously reported (webappendix).
To determine the effects of patients’ antibodies on the number of NMDA-receptor clusters, neurons were incubated with either patients’ or control CSF applied daily from day 7 to day 14 in vitro. Each day, 20 μL of the 300 μL total medium was replaced with 20 μL of CSF. In parallel, neurons were incubated with patients’ CSF from day 7 to day 10 followed by incubation with control CSF from day 10 to day 14. On day 10 or day 14, neurons were washed, fixed, permeabilised and immunostained. Imaging and quantification were done as previously described (webappendix).
Cultures of embryonic rat hippocampal neurons were incubated for 24 h with IgG isolated from serum of patients or control individuals. Cell-surface proteins were biotinylated and then isolated from the whole cell lysate. The cell-surface fraction of NR1 from neurons treated with either patients’ or control IgG were then quantified by immunoblot analysis (webappendix).

Statistical analysis

Statistical analyses were done with SAS 9.1 (version 9.1, SAS Institute, Cary, NC, USA). Contingency tables were analysed with Fisher’s two-sided exact test. Differences in antibody titres among groups were analysed with the Kruskal-Wallis and Wilcoxon sum rank tests, with the Bonferroni correction for pairwise tests. The effects of IgG and CSF on neuronal cultures were analysed with the Kruskal-Wallis non-parametric ANOVA followed by Dunn’s pairwise comparison.

Role of the funding source

The sponsor of the study had no role in study design, data collection, data analysis, data interpretation, or the writing of the report. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication.

Results

Table 1 summarises the clinical information. 86 patients who could be assessed had headache, low-grade fever, or a non-specific viral-like illness within 2 weeks before hospital admission. 77 patients presented with prominent psychiatric symptoms, including anxiety, agitation, bizarre behaviour, delusional or paranoid thoughts, and visual or auditory hallucinations. 23 presented with short-term memory loss or seizures alone or associated with psychiatric manifestations.
Table 1
Characteristics and clinical features
During the first 3 weeks of symptom presentation, 76 patients had seizures. 88 patients developed decreased consciousness, progressing to a catatonic-like state, with periods of akinesis alternating with agitation, and diminished or paradoxical responses to stimuli (eg, no response to pain but resisting eye opening). Some patients mumbled unintelligible words or had echolalia. Eye contact or visual tracking was absent or inconsistent. During this clinical stage, large proportions of patients developed dyskinesias, autonomic instability, and central hypoventilation (median time of ventilatory support, 8 weeks; range 2–40 weeks). Orofacial dyskinesias were the most common; these included grimacing, masticatory-like movements, and forceful jaw opening and closing, resulting in lip and tongue injuries or broken teeth. 37 patients had cardiac dysrhythmias, including tachycardia or bradycardia, with prolonged pauses in seven patients; four needed pacemakers. 52 patients had dyskinesias, autonomic instability, and hypoventilation, 27 patients had two of these symptoms, and 14 had just one; the remaining seven patients developed a milder syndrome of seizures and psychiatric symptoms.
Table 2 shows EEG, brain MRI, and CSF findings. 92 patients had extensive EEG monitoring, 77% had generalised or predominantly frontotemporal slow or disorganised activity (delta-theta) without epileptic discharges. Of the 100 patients, 55 had increased signal on MRI fluid-attenuated inversion recovery or T2 sequences; 14 of these patients had faint or transient contrast enhancement of the cerebral cortex, overlaying meninges, or basal ganglia. These findings were limited to a single area of the brain in 19 patients: 16 had abnormalities in medial temporal lobes, two in the corpus callosum, and one in the brainstem. Follow-up studies in 70 patients showed that many of those who recovered or were left with mild deficits had improved or normalised MRI (webappendix).
Table 2
Ancillary tests and treatment
14 patients had brain biopsy: findings for two were normal, 12 showed mild perivascular lymphocytic cuffng, and ten microglial activation. All had negative results for neuronophagic nodules and viral assays.
58 (59%) of 98 patients had a neoplasm (table 2); two died before tumour assessment. All but one of these patients developed neurological symptoms before the tumour diagnosis (median 8 weeks, range 1–380 weeks). In six patients, the tumour was diagnosed after recovery from the encephalitis (56–380 months). Ovarian teratoma identified with CT, MRI, or ultrasound was a common tumour type (median size 6 cm, range 1–22 cm). Eight patients had bilateral teratomas; four were synchronous, two had history of a contralateral teratoma, and two developed contralateral teratomas before recurrence of the encephalitis. All teratomas contained nervous tissue; 25 were examined for expression of NMDA receptors, and all were positive (data not shown).
One boy (11 years old, without tumour) and 21 women and girls were younger than 19 years (median 15 years, range 5–18 years); 12 had an ovarian teratoma (five with immature features), and nine had no tumour. Metastases were identified only in one man with immature teratoma of the testis.
Seven patients with cancer did not have tumour resection (one small-cell lung cancer, two teratomas found at autopsy, four not removed). Six patients who had tumours removed did not receive immunotherapy (table 2). 40 of 42 patients without tumour had immunotherapy and two had supportive care.
Median follow-up was 17 months (1–194 months): 47 patients had full recovery, 28 mild stable deficits, 18 severe deficits, and seven died as a result of the neurological disorder. Patients whose tumour was identified and removed within the first 4 months of the onset of the neurological disease had better outcome than the rest of the patients (figure 2). The median time from symptom presentation to initial signs of improvement was 8 weeks (range 2–24 weeks) for the group of patients with early tumour treatment, 11 weeks (4–40 weeks) for the group whose tumour was treated late or not treated, and 10 weeks (2–50 weeks) for the group without tumour (Kruskal-Wallis, p=0.10)
Figure 2
Response to treatment
The median duration of hospitalisation was 2.5 months (range 1–14 months). While hospitalised, seven patients had high levels of serum creatine kinase, six developed pulmonary embolism, six transient aphasia, four hemiparesis, and four tetraparesis. After discharge, 64 (85%) of the 75 patients who were left with mild deficits or eventually attained full recovery had signs of frontal-lobe dysfunction including poor attention and planning, impulsivity, and behavioral dysinhibition; 20 (27%) had prominent sleep dysfunction, including hypersomnia and inversion of sleep patterns.
15 patients had one to three relapses of encephalitis (webtable 2). The median time between initial presentation and last relapse was 18 months (1–84 months). Relapses were less common in patients with early tumour treatment (1 of 36) than in other patients (14 of 64; p=0.009), including patients whose tumour was treated late (six of 22; p=0.009) and patients without tumour (eight of 42; p=0.03). None of the patients was receiving immunotherapy at the time of the neurological relapse.
Seven patients died of the neurological disorder (webappendix), although the diagnosis was established retrospectively by examining archived CSF for all of them.
Analysis of the reactivity of patients’ sera or CSF against the indicated NMDA-receptor subunits or heteromers showed that antibody reactivity was not modified by changing the NR2 subunit (A, B, C, or D) and was retained by homomers of NR1 (webtable 3). Having established that NR1 was recognised by all patients’ antibodies, we investigated the epitope region by use of a plasmid (NR1d4) that encodes an NR1 subunit lacking amino-acid residues 25–380 that can nevertheless assemble with NR2B. The successful expression of NR1d4–NR2B in HEK293 cells was confirmed by immunocytochemistry with the indicated mouse and rabbit antibodies against NR1 and NR2B (data not shown). The use of these heteromers abrogated the reactivity of sera or CSF from 92 patients’, and substantially decreased the reactivity of the samples of the remaining eight cases. Hence the main epitope region recognised by all patients’ antibodies lies within the extracellular region of the NR1 subunit (webtable 3).
To determine whether patients had intrathecal synthesis of antibodies, we first measured the integrity of the blood–brain barrier. Of 58 patients with paired serum and CSF available, 53 had preserved integrity of the blood–brainbarrier. Analysis of normalized concentrations of IgG showed that all 53 patients had higher concentrations of antibodies in CSF than in sera, indicating intrathecal synthesis of antibodies (figure 3). Of the 83 patients whose CSF was available, those with tumours had higher antibody titres than those without (figure 3). Four patients who died and whose CSF was available were among the group with the highest titres, whereas the seven patients with milder syndromes had the lowest titres (data not shown). Patients who improved had a parallel decrease of serum titres, whereas those who did not improve maintained high titres in CSF and serum (figure 3). Follow-up CSF titres were not obtained in most patients after improvement.
Figure 3
Analysis of NR1 antibody titres
To assess the effect of patients’ antibodies on neuronal cultures, we first determined the extent of immunolabelling of NR1 (or NMDA receptor) clusters in postsynaptic dendrites. Patients’ antibodies labelled nearly all clusters of NMDA receptors (figure 4). This antibody binding did not cause apoptosis (data not shown). However, adding patients’ IgG to rat hippocampal neuronal cultures produced a concentration-dependent decrease of the cell-surface fraction of NMDA receptors (figure 5). IgG from patients with high antibody titres produced a greater decrease of NMDA receptors than IgG from patients with low antibody titres (data not shown).
Figure 4
Immunolabelling of neuronal NR1 clusters
Figure 5
Effect of antibodies on the number of NMDA-receptor clusters in live neurons
The effect of patients’ antibodies on clusters of NMDA receptors in postsynaptic dendrites was quantified by confocal microscopy. Neurons treated with patients’ CSF for 3 days or 7 days had fewer clusters of NMDA receptors per length of postsynaptic dendrite than neurons treated with control CSF. By contrast, neurons treated for 3 days with patients’ CSF followed by 4 days with control CSF had similar numbers of clusters of NMDA receptors to those in neurons treated only with control CSF (figure 5). Patients’ antibodies did not change the concentrations of the postsynaptic protein PSD-95 (figure 5). Together, these findings show that patients’ antibodies produce a selective and reversible decrease of NMDA-receptor clusters in postsynaptic dendrites.

Discussion

Of 100 patients with anti-NMDA-receptor encephalitis, a disorder that associates with antibodies against the NR1 subunit of the receptor, many were initially seen by psychiatrists or admitted to psychiatric centres but subsequently developed seizures, decline of consciousness, and complex symptoms requiring multidisciplinary care. While poorly responsive or in a catatonic-like state, 93 patients developed hypoventilation, autonomic imbalance, or abnormal movements, all overlapping in 52 patients. 59% of patients had a tumour, most commonly ovarian teratoma. Despite the severity of the disorder, 75 patients recovered and 25 had severe deficits or died.
This disorder largely affects young people, and its diagnosis is facilitated by the characteristic clinical picture that develops in association with CSF pleocytosis. By contrast to the consistency of the clinical picture, MRI findings are less predictable; only 55% of patients had increased FLAIR or T2 signal in one or several brain regions, without significant correlation with patients’ symptoms (data not shown). Our study indicates that 41% of patients with anti-NMDA-receptor encephalitis do not have a clinically detectable tumour, and that men and children can also be affected. Therefore, although the presence of a tumour that expresses NMDA receptors likely contributes to breaking immune tolerance, other unknown immunological triggers seem to be involved. This paradigm is similar to the Lambert-Eaton myasthenic syndrome, an antibody-mediated disorder of the neuromuscular junction that can occur with or without tumour association. In Lambert-Eaton myasthenic syndrome the presence of a small-cell lung cancer confers a poor neurological prognosis; however, in anti-NMDA-receptor encephalitis, detection of teratoma is a good prognostic factor, probably because this tumour is curable.
In anti-NMDA-receptor encephalitis the high prevalence of prodromal viral-like symptoms is intriguing. Direct viral pathogenesis is unlikely because extensive studies of CSF samples, brain biopsies, and autopsies were negative for viruses (data not shown). Whether the prodromal symptoms form part of an early immune activation,, or result from a non-specific infection that facilitates crossing of the blood–brain barrier by the immune response is unknown.,Nevertheless, the immune response eventually predominates in the nervous system as suggested by the high frequency of pleocytosis, oligoclonal bands, and intrathecal synthesis of NR1 antibodies. In general, patients with an underlying tumour develop more robust immune responses than those without a tumour.
A pathogenic role of patients’ antibodies is suggested by the correlation between antibody titres and neurological outcome and by the decrease in number of postsynaptic clusters of NMDA receptors caused by patients’ antibodies. The latter effect was reversed by removing the antibodies from the cultures, explaining the potential reversibility of patients’ symptoms. Consistent with this antibody-induced decrease in the numbers of NMDA receptors, several NMDA-receptor antagonists such as MK801, ketamine, and phencyclidine cause symptoms similar to anti-NMDA-receptor encephalitis, including psychotic behaviour,, signs of involvement of dopaminergic pathways (rigidity, dystonia, orofacial movements, tremor)and autonomic dysfunction (cardiac dysrhythmia, hypertension, hypersalivation).,,,Furthermore, disruption of NR1 in animals results in hypoventilation.
A characteristic feature of patients who recover from anti-NMDA-receptor encephalitis is a persisting amnesia of the entire process (data not shown). This feature is compatible with disruption of the mechanisms of synaptic plasticity, thought to underlie learning and memory, in which the NMDA receptors play a key part.
Recovery from this disorder is typically slow, and symptoms may relapse, especially in patients with undetected or recurrent tumours and patients with no associated tumours. Some of these patients may have an occult tumour; however, in only one of seven patients who underwent exploratory laparotomy was a tumour found (sex-cord stromal tumour; data not shown). A possible explanation for the slow recovery could be the inability of most commonly used treatments (corticosteroids, plasma exchange, intravenous immunoglobulin) to result in a rapid and sustained control of the immune response within the CNS. For example, in a few patients whose CSF was obtained during neurological improvement, the decrease of CSF antibody titres was substantially slower than that of serum titres. Furthermore, 13 of 17 patients unresponsive to the above therapies, responded to cyclophosphamide (five), rituximab (six), or both (two; data not shown), drugs that are effective in other immune-mediated disorders of the CNS.,
Anti-NMDA-receptor encephalitis represents a new category of immune-mediated disorder that is often paraneoplastic, treatable, and can be diagnosed serologically. Future studies should clarify the best type and duration of immunotherapy, the role of prodromal events in triggering the immune response, and the molecular mechanisms involved in decreasing the number of NMDA receptors.