Back to the future: encephalitis lethargica as an autoimmune disorder?

More than 100 years after its emergence, the exact pathophysiological mechanisms underlying encephalitis lethargica (EL) are still elusive and awaiting convincing and complete elucidation. This article summarizes arguments proposed over time to support or refute the hypothesis of EL as an autoimmune neuropsychiatric disorder triggered by an infectious process. It also provides a critical evaluation of modern cases labeled as EL and a comprehensive differential diagnosis of autoimmune neurological conditions that could mimic EL. The evidence supporting the autoimmune nature of historical EL is sparse and not entirely convincing. It is possible that autoimmune mechanisms were involved in the pathogenesis of this disease as an idiosyncratic response to a yet unidentified infectious agent in genetically predisposed individuals. Although there has been an increase in the incidence of presumed autoimmune encephalomyelitis since the peak of EL pandemics, most evidence does not support an underlying autoimmune mechanism. There are significant differences between historical and recent EL cases in terms of clinical symptomatology, epidemiology, and neuropathological features, suggesting that they are different entities with only superficial similarity. The term "encephalitis lethargica," still frequently used in the medical literature, should not be used for cases occurring at present in the sporadic form. Historical EL should be kept apart from recent EL, as they differ in important aspects.

A history of oculogyric crises during the encephalitis lethargica pandemic

A pandemic of what came to be known as encephalitis lethargica spread starting in the winter of 1916-1917 and continued into the 1930s. Neurological after-effects, namely permanent parkinsonian syndromes and various abnormal movements, permanently disabled the survivors of the one or two million victims, often children or young adults. Among them, a small proportion developed a symptom that was little known up to that point and that is currently exceptional: oculogyric crises; that is, a lateralised, dystonic upward movement of the eyes known as a tonic eye fit. This paper proposes a history of the recognition of this symptom, its inclusion in the neurological nosography, and the pathophysiological hypotheses postulated a century ago.

Contemporary encephalitis lethargica presenting with agitated catatonia, stereotypy, and dystonia-parkinsonism

Encephalitis lethargica (EL) syndrome was classically described by Von Economo and has somnolent-ophthalmoplegic, hyperkinetic, and amyostatic-akinetic forms. We describe 2 recent cases of EL characterized by an acute encephalitis with mixed movement disorders (dystonia-Parkinsonism plus stereotypy) and psychiatric disorders (agitated catatonia, coprolalia, and echo phenomena). Both patients suffered concurrent hyperkinetic and Parkinsonian features resulting in therapeutic challenges. Bradykinetic features responded to dopamine replacement therapy and both patients also had adverse affects to dopamine antagonists (oculogyric crises plus neuroleptic malignant syndrome). Investigation was unremarkable other than the presence of CSF lymphocytosis and oligoclonal bands. Despite prolonged in-patient stays and intensive care management, both patients have made complete recoveries. We believe these cases support the hypothesis that this syndrome is an inflammatory encephalitis that specifically effects dopamine neurotransmission.

Steroid-responsive encephalitis lethargica syndrome with malignant catatonia

We report a 47-year-old man who is considered to have sporadic encephalitis lethargica (EL). He presented with hyperpyrexia, lethargy, akinetic mutism, and posture of decorticate rigidity following coma and respiratory failure. Intravenous methylprednisolone pulse therapy improved his condition rapidly and remarkably. Electroencephalography (EEG) showed severe diffuse slow waves of bilateral frontal dominancy, and paralleled the clinical course. Our patient fulfilled the diagnostic criteria for malignant catatonia, so we diagnosed secondary malignant catatonia due to EL syndrome. The effect of corticosteroid treatment remains controversial in encephalitis; however, some EL syndrome patients exhibit an excellent response to corticosteroid treatment. Therefore, EL syndrome may be secondary to autoimmunity against deep grey matter. It is important to distinguish secondary catatonia due to general medical conditions from psychiatric catatonia and to choose a treatment suitable for the medical condition.

Progressive supranuclear palsy: New disease or variant of postencephalitic parkinsonism?

We review the etiological importance of the epidemic encephalitis for progressive supranuclear palsy (PSP) and addresses the question of whether the explosion of PSP literature in the mid-20th century reflects the appearance of a new disease. We examined 2,000 studies on Parkinson's disease from 1861 to 1963 and found PSP-like cases in the past, before the epidemic encephalitis era. It can be assumed that PSP is neither a new disease nor a variant of postencephalitic parkinsonism.

von Economo encephalitis

In April 1917, Dr Constantin von Economo presented his clinical and pathologic findings of a new disease--soon to be part of a worldwide epidemic--before the Vienna Psychiatric Society. He named it encephalitis lethargica. After years of careful observation, he collected and analyzed thousands of cases and classified them into 3 clinical syndromes: somnolent-ophthalmoplegic, hyperkinetic, and amyostatic-akinetic forms. He described the now legendary postencephalitic Parkinsonism, noting that symptoms could emerge years after the original infection, often without signs of prodromal "flu." He emphasized the neuropathologic findings: inflammatory changes in the tegmentum of the midbrain accounting for the sleep disturbance and ocular signs. After encountering sporadic cases following the epidemic, he concluded that the somnolent-ophthalmoplegic syndrome was the primary expression of encephalitis lethargica. This article outlines the observations and conclusions of Dr von Economo during and after the epidemic through seminal quotations primarily from his published works, as well as from more recent reports.

FDG- and Dopa-PET in postencephalitic parkinsonism

We report a case of a 74-year old woman who following an acute virus encephalitis developed an akinetic-rigid Parkinson syndrome with tremor, hypokinesia, hypomimia, rigidity and cogwheel phenomenon in all four extremities, brady-dysdiadochokinesia as well as myoclonic jerks of the arms. Many of the clinical features of this postencephalitic parkinsonism (PEP) suggested the diagnosis of sporadic encephalitis lethargica, first described by von Economo 1917. Cerebral spinal fluid showed signs of a viral encephalitis, and a positive influenza A IgA-antibody titer (1:>160) in the viral serologic screen was found. Positron emission tomography (PET) showed an altered pattern of glucose- and dopa-metabolism clearly different from findings in idiopathic Parkinson syndrome (IPS). The acute lack of inhibitory input from the substantia nigra pars compacta to the striatum could explain the different metabolic patterns in our case in comparison to IPS patients. Our findings indicate that PEP may also be caused by influenza A and furthermore that PET clearly distinguishes PEP from IPS.

An akinetic-rigid syndrome, depression, and stereotypies in a young man

A young man is presented who developed an akinetic-rigid syndrome shortly after a minor illness. Rituals and stereoptypies were prominent. At its most severe he was unable to feed himself. There was no response to L-dopa/cardopa treatment. A course of ECT was followed by a marked improvement in his condition. Attempts to stop ECT for more than a week have led to recurrence of his bradykinesia.

Supranuclear gaze palsy and eyelid apraxia in postencephalitic parkinsonism

We describe six patients with clinicopathologically confirmed post-encephalitic parkinsonism (PEP) in whom oculomotor abnormalities developed several years after suffering the initial episode of encephalitis lethargica. Four of the cases had vertical supranuclear gaze palsy and two eyelid apraxia, features typically associated with progressive supranuclear palsy (PSP). Our findings indicate that the presence of gaze palsy alone may not be a reliable clinical discriminator between PEP and PSP. Involvement of the dorsal central gray nucleus, nucleus centralis pontis oralis, nucleus dorsal raphe interpositus, rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), nucleus interstitialis of Cajal, nucleus of the posterior commissure, pedunculopontine nuclei and frontal cortex was observed in several of our PEP cases and may contribute to the oculomotor abnormalities in this disorder. Whether the dorsal tegmental nucleus, caudal to the supratrochlear nucleus, severely affected in all our PEP cases, has a role in vertical gaze needs to be further studied.

Influenza virus and neurological diseases

Influenza viruses rarely cause acute encephalopathy. Post-influenzal encephalitis, which occurs a few weeks after recovery from influenza is thought to be an autoimmune process associated with demyelination and vasculopathy. It has been suggested that Economo lethargic encephalitis followed by postencephalitic Parkinsonism was associated with the influenza A epidemic of 1918 (Spanish flu). The incidence of Reye's syndrome has markedly decreased due to the avoidance of salicylates in the treatment of influenza or varicella. One inactivated flu vaccine is thought to have caused Guillain Barre syndrome due to molecular mimicry between viral protein and myelin, which triggered autoimmune responses. The persistence of influenza virus genes in neural cells as one of the causes of chronic degenerative diseases of the central nervous system by inducing apoptosis of the host cells is yet to be proven.

Juvenile parkinsonism caused by chronic meningoencephalitis: a clinicopathological study

After a six-year history of poor concentration, intellectual and growth retardation, and a one-year history of absences, an 11-year-old girl developed parkinsonism and thereafter had a progressive, predominantly extrapyramidal disorder for the next nine years, until her death at age 20. Other clinical features included pyramidal signs, peripheral neuropathy and sideroblastic anemia. Despite a clinical course suggestive of a degenerative condition, the principal findings on examination of the brain were chronic meningitis, brainstem encephalitis and mild diffuse cerebral gliosis. Extensive investigations failed to demonstrate an infective agent, either in life or by post mortem examination.

[Encephalitis lethargica--a neuropsychiatric disease]

Encephalitis lethargica is presented as an exemplaric neuropsychiatric illness. Its history, the symptoms and the diagnostics, as well as its pathology and therapy are illuminated. Finally, specific problems and questions with regard to encephalitis lethargica are discussed: the question of a viral genesis and of a probable reappearance of the apparently disappeared encephalitis lethargica, the problems concerning the account for the neurological and psychiatric symptoms, and the question of role and function of the basal ganglia.

Postvaccinal parkinsonism

A 5-year-old boy, with a history of fever beginning 15 days after a vaccination for measles, developed a rigid-akinetic syndrome 3 days after the fever began. A spinal tap obtained 1 week after the onset of fever showed pleocytosis with a monocellular pattern. A CT scan of the head and EEG did not disclose any abnormality. An MRI performed 3 months after the event, however, showed clear-cut evidence of bilateral substantia nigra lesions, suggesting secondary gliosis. The response to levodopa was good, but adverse reactions appeared early. The child is now 7 years old. Bromocriptine, deprenyl, and levodopa have produced a remarkable improvement of the parkinsonian features.

Encephalitis lethargica-like illness in a five-year-old

A five-year-old boy presented with an encephalitis lethargica-like illness, characterised by somnolence, mutism and Parkinsonian rigidity two weeks after an acute exanthem. Investigation revealed increased serum measles antibody titre. He made a complete recovery. Encephalitis lethargica associated with Parkinsonism in childhood is rare and usually carries a poor prognosis.

Diagnostic problems in Parkinson's disease

The diagnosis of Parkinson's disease is not as easy as previously claimed, and presents a number of pitfalls. We present three rules, or aphorisms, to help the general practitioner in overcoming these diagnostic difficulties: Know well the basic disease and its symptoms. Use tricks to elicit apparently absent 'primary' symptoms. Beware of unusual symptoms or case histories. Examples of difficulties encountered at each level are given. Such analysis should permit the physician to classify his extrapyramidal patient within one of the many types of 'parkinsonism' as shown in Table 1.

Neurological assessment

Neurological assessment of certain movement disorders is described with emphasis on Parkinson's disease. In addition, abnormal behavior and changes in affect are given. Changes in neurological status, i.e., Bradykinesia, rigidity, gait changes, hand-writing irregularity, postural reflexes are outlined. The differential diagnosis of the disease is also indicated in addition to prognosis and to the biochemical correlates of Parkinson's disease.

Oculogyric crises and parkinsonism. A case of recent onset

Oculogyric crisis in association with postencephalitic parkinsonism has been reported only following encephalitis lethargica (Economo's disease). Generally, it has been assumed that this phenomenon would fade away with the demise of these postencephalitic patients. Therefore, we report a case of recent onset of persistent oculogyric crisis with parkinsonism in a 35-year-old man following an apparent attack of encephalitis in 1972.

A controlled study of dementia in Parkinson's disease

Tests of cognitive functions were carried out in a group of patients with Parkinson's disease and repeated after a three-year interval. Comparison was made with a control group drawn from a population of psychiatric patients, matched for age and sex. No differences in cognitive functions were found between the groups, either initially, or between those surviving for three years. Deaths among the index group included a high proportion of patients with cognitive impairment and there was an increasing prevalence and severity of dementia in the index group which exceeded that observed in the control group. Requirements for a methodologically sound study of dementia in Parkinson's disease are discussed.

Post-encephalitic Parkinsonism: current experience

The diagnosis of post-encephalitic Parkinsonism is rarely entertained today. In this paper we discuss eight recent patients, six of whom presented in the last 20 years, that conform to the diagnosis of encephalitis lethargica. The clinical features by which the diagnosis may be made are defined so that a contemporary definition of this disorder may be attained.

Symptomatic Parkinsonism

Parkinson's disease, 'paralysis agitans', is characterized by a number of abnormalities. A similar clinical picture may be symptomatic of other disturbances: these are briefly described and the differential diagnosis is discussed.

Disability and progression in Parkinson's disease

Disability and progression in Parkinson's disease prior to levodopa treatment was investigated in a random group of 442 patients representing 91 per cent of all known cases with Parkinson's disease in a defined area. Almost half the patients were totally independent, 27 per cent needed help occasionally, and 25 per cent were dependent on other people. Ten per cent of the patients had only unilateral symptoms, 57 per cent had bilateral involvement with mild disability, 20 per cent had a moderately advanced disease, and 13 per cent were severely idsabled. A great variation was found in progression rates. In individual cases, however, the progression rate seemed to be relatively fixed. Concurrent arteriosclerosis was found to worsen the prognosis, whereas the beginning of the disease with tremor and the occurrence of prominent tremor promised a slower progression. Twenty-six patients with only unilateral symptoms 10 years after onset of the disease were found to correspond to postencephalitic patients in age structure, and in such cases a history of preceeding viral infection of the central nervous system was observed on four occasions.