Cognitive recovery instead of decline after acute encephalitis: a prospective follow up study

Outcome and Sequelae of Infectious Encephalitis

Acute infectious encephalitis is a widely studied clinical syndrome. Although identified almost 100 years ago, its immediate and delayed consequences are still neglected despite their high frequency and possible severity. We reviewed the available data on sequelae and persisting symptoms following infectious encephalitis with the aim of characterizing the clinical picture of these patients at months to years after hospitalization. We searched PubMed for case series involving sequelae after infectious encephalitis. We carried out a narrative review of the literature on encephalitis caused by members of the Herpesviridae family (herpes simplex virus, varicella zoster virus, and human herpesvirus-6), members of the Flaviviridae family (West Nile virus, tick-borne encephalitis virus, and Japanese encephalitis virus), alphaviruses, and Nipah virus. We retrieved 41 studies that yielded original data involving 3,072 adult patients evaluated after infectious encephalitis. At least one of the five domains of cognitive outcome, psychiatric disorders, neurological deficits, global functioning, and quality of life was investigated in the reviewed studies. Various tests were used in the 41 studies and the investigation took place at different times after hospital discharge. The results showed that most patients are discharged with impairments, with frequent deficits in cognitive function such as memory loss or attention disorders. Sequelae tend to improve within several years following flavivirus or Nipah virus infection, but long-term data are scarce for other pathogens. Further research is needed to better understand the extent of sequelae after infectious encephalitis, and to propose a standardized assessment method and assess the rehabilitation efficacy in these patients.

Establishment of a consensus protocol to explore the brain pathobiome in patients with mild cognitive impairment and Alzheimer's disease: Research outline and call for collaboration

Microbial infections of the brain can lead to dementia, and for many decades microbial infections have been implicated in Alzheimer's disease (AD) pathology. However, a causal role for infection in AD remains contentious, and the lack of standardized detection methodologies has led to inconsistent detection/identification of microbes in AD brains. There is a need for a consensus methodology; the Alzheimer's Pathobiome Initiative aims to perform comparative molecular analyses of microbes in post mortem brains versus cerebrospinal fluid, blood, olfactory neuroepithelium, oral/nasopharyngeal tissue, bronchoalveolar, urinary, and gut/stool samples. Diverse extraction methodologies, polymerase chain reaction and sequencing techniques, and bioinformatic tools will be evaluated, in addition to direct microbial culture and metabolomic techniques. The goal is to provide a roadmap for detecting infectious agents in patients with mild cognitive impairment or AD. Positive findings would then prompt tailoring of antimicrobial treatments that might attenuate or remit mounting clinical deficits in a subset of patients.

Challenges for nurses in caring for patients with acute encephalitis: lack of knowledge, time and rehabilitation

AIM

To explore the experiences of registered nurses providing care to adult patients affected by encephalitis, from admission into hospital through to discharge.

STUDY DESIGN

A qualitative phenomenological methodology was used. Sample and setting: Eight registered nurses in a city centre teaching hospital.

METHODS

Data collection took place using in-depth, semi-structured interviews. Data were analysed and themes identified using framework analysis.

FINDINGS

Three key findings were identified: nurses felt that they lacked knowledge of encephalitis, lacked time to give these patients the care they needed, and they lacked access to rehabilitation for patients with encephalitis.

CONCLUSION

This study provides the first evidence on nurses' experiences of providing care to patients affected by encephalitis. It has shown that they often lack the knowledge and time to give adequate support to patients. They also lack access to rehabilitation for these patients.

Association between scrub typhus encephalitis and diffusion tensor tractography detection of Papez circuit injury: A case report

BACKGROUND

It is difficult to restore the cognitive functions of patients with impaired cognition caused by brain injury. Diffusion tensor imaging can visualize the integrity of neural tracts in the white matter (WM) three-dimensionally. It is unclear whether encephalitis following scrub typhus damages the WM. For the first time, we aimed to report diffusion tensor tractography (DTT) findings in a chronic patient with cognitive impairment following scrub typhus encephalitis, which revealed injury to the Papez circuit of the WM.

CASE SUMMARY

A 70-year-old male patient was affected by encephalitis caused by scrub typhus that occurred 23 years ago. He had poor cognition and his clinical examination findings were as follows: Mini-Mental Status Examination score, 14; and handgrip strength (right/left, kg), 32.3/31.3. DTT revealed serious injuries of the left thalamocingulate tract and right mammillothalamic tract in the Papez circuit, and a partial injury of the anterior part of the fornix.

CONCLUSION

Using DTT, we found a relationship between cognitive impairment and the integrity of the Papez circuit following scrub typhus.

Herpes Simplex Virus Type-1 Infection: Associations with Inflammation and Cognitive Aging in Relation to Schizophrenia

Most persons experience cognitive decline as they grow older. The term "cognitive aging," coined to describe milder varieties of cognitive decline, is likely to be due to multiple causes. Persistent or repeated infections of the central nervous system (whether subclinical or diagnosable) can cause damage to neurons directly or indirectly through inflammation resulting in incremental neuronal damage, thus eroding cognitive reserve. This possibility has not been considered widely. We evaluated the data linking persistent infection with herpes simplex virus type 1 (HSV-1) and cognitive aging by applying the Bradford Hill criteria. Despite inherent problems in establishing causal relations for chronic disorders, our analyses suggest plausible links. These studies are pertinent for patients with schizophrenia, who are particularly vulnerable due to disorder-related cognitive impairment. Further investigations are warranted to test a causal hypothesis, particularly prospective studies and intervention studies.

Treatable causes of adult-onset rapid cognitive impairment

OBJECTIVES

Acute and subacute cognitive decline, defined collectively as rapid cognitive impairment (RCI), is attributed to diverse disorders and brings great challenges for differential diagnosis. In this study we investigated the RCI patients to determine the underlying causes and the cognitive outcome of the treatable RCI.

PATIENTS AND METHODS

We reviewed medical records of consecutively hospitalized patients (n = 346) with significant and new cognitive dysfunction between January 2014 and December 2015. Based on the duration of their cognitive dysfunction, patients were divided into two groups with the RCI (< 12 months) and the chronic cognitive impairment (CCI, ≥ 12 months), respectively. Etiologies of the RCI and the CCI were analyzed; the cognitive outcomes of the RCI patients with the treatable disorders were assessed in the follow-up visits.

RESULTS

Potentially treatable or reversible causes were identified in 134 (72%) of 187 RCI patients and in 34 (21%) of 159 CCI patients. The causes in the 134 (72%) RCI patients were immune/inflammation (50, 37%), infection (30, 22%), vascular diseases (29, 22%), neoplasm (16, 12%), metabolic/toxic disorders (7, 5%), and others (2, 1%). The treatable disorders found in both the RCI and the CCI patients were vascular diseases, autoimmune encephalitis, viral encephalitis, inflammatory demyelinating diseases, Hashimoto encephalopathy, neurosyphilis, hydrocephalus, and Vitamin B12 deficiency. Total 114 RCI patients with the treatable disorders were followed up for 6∼39 (median 21) months. Poor cognitive outcomes were found in 24 (21%) of the 114 followed-up patients, comprising patients with infection (1, 3%), immune/inflammation (12, 25%), vascular diseases (8, 28%), and metabolic/toxic disorders (3, 43%).

CONCLUSIONS

Treatable or reversible causes are common underlying RCI. Poor outcomes with severe cognitive deficits are considerably present in the treatable RCI patients and result in permanent dementia.

Plasticity versus chronicity: Stable performance on category fluency 40 years post-onset

What is the long-term trajectory of semantic memory deficits in patients who have suffered structural brain damage? Memory is, per definition, a changing faculty. The traditional view is that after an initial recovery period, the mature human brain has little capacity to repair or reorganize. More recently, it has been suggested that the central nervous system may be more plastic with the ability to change in neural structure, connectivity, and function. The latter observations are, however, largely based on normal learning in healthy subjects. Here, we report a patient who suffered bilateral ventro-medial damage after presumed herpes encephalitis in 1971. He was seen regularly in the eighties, and we recently had the opportunity to re-assess his semantic memory deficits. On semantic category fluency, he showed a very clear category-specific deficit performing better that control data on non-living categories and significantly worse on living items. Recent testing showed that his impairments have remained unchanged for more than 40 years. We suggest cautiousness when extrapolating the concept of brain plasticity, as observed during normal learning, to plasticity in the context of structural brain damage.

Long-term outcome of acute encephalitis of unknown aetiology in adults

Encephalitis is caused by a variety of conditions, including infections of the brain by a wide range of pathogens. A substantial number of cases of encephalitis defy all attempts at identifying a specific cause. Little is known about the long-term prognosis in patients with encephalitis of unknown aetiology, which complicates their management during the acute illness. To learn more about the prognosis of patients with encephalitis of unknown aetiology, patients in whom no aetiology could be identified were examined in a large, single-centre encephalitis cohort. In addition to analysing the clinical data of the acute illness, surviving patients were assessed by telephone interview a minimum of 2 years after the acute illness by applying a standardized test battery. Of the patients with encephalitis who qualified for inclusion (n = 203), 39 patients (19.2%) had encephalitis of unknown aetiology. The case fatality in these patients was 12.8%. Among the survivors, 53% suffered from various neurological sequelae, most often attention and sensory deficits. Among the features at presentation that were associated with adverse outcome were older age, increased C-reactive protein, coma and a high percentage of polymorphonuclear cells in the cerebrospinal fluid. In conclusion, the outcome in an unselected cohort of patients with encephalitis of unknown aetiology was marked by substantial case fatality and by long-term neurological deficits in approximately one-half of the surviving patients. Certain features on admission predicted an unfavourable outcome.

The epidemiology of acute encephalitis

Encephalitis means inflammation of the brain matter. Despite being a rare condition, encephalitis is of public health importance worldwide because it has high morbidity and mortality. Yet, many details about its epidemiology have yet to be elucidated. This review attempts to summarise what is known about the epidemiology of the infective causes of encephalitis and is based on a literature search of the Medline archives. Infection is the most common cause identified, with viruses being the most important known aetiological agents. Incidence varies between studies but is generally between 3.5 and 7.4 per 100,000 patient-years. Encephalitis affects peoples of all ages; however, incidence is higher in the paediatric population. Although both sexes are affected, most studies have shown a slight predominance in males. Encephalitis occurs worldwide; some aetiologies have a global distribution (herpesviruses) while others are geographically restricted (arboviruses). Although definite epidemiological trends are evident, it is difficult to make generalisations as few population-based studies exist, most cases are not reported to health authorities, and many possible pathogens are implicated but in most cases a cause is never found. A better understanding of the epidemiology of this devastating disease will pave the way for better prevention and control strategies.

Neuropsychological and psychiatric profiles in acute encephalitis in adults

Acute encephalitis is an inflammation of brain tissue that can result from activity in the central nervous system (CNS) of a number of viruses. Although the neurological and psychiatric effects of encephalitis in the acute phase of the illness are well-known (Caroff, Mann, Gliatto, Sullivan, & Campbell, 2001), larger scale studies of the pattern of neuropsychological and psychiatric impairment following recovery from the acute inflammatory phase are less apparent. This paper reports the results of neuropsychological testing with a range of standardised cognitive measures in a case series of long-term post-acute participants. Psychiatric abnormality is examined using the SCL-90-R self-report scale of distress (Derogatis, 1983). We also examined the role of emerging insight in the aetiology of depression in this population. Two clusters of cognitive dysfunction were observed, one group of primarily herpes simplex cases showing a severe generalised deficit across a number of cognitive domains and a second cluster showing a variety of more isolated disorders of executive function. Abnormally high levels of distress were reported by participants, with depression, obsessive-compulsive symptoms, interpersonal sensitivity and phobic anxiety most significantly increased. Depression was found to be least severe in those with most accurate insight into their problems. Examining the correlations between cognitive and psychiatric test results demonstrates a relationship between depression and interpersonal anxiety and specific cognitive measures. Obsessive-compulsive behaviour and phobic anxiety, however, appear to exist independently of the assessed cognitive deficits.

Neuropsychological sequelae of acute-onset sporadic viral encephalitis

Acute encephalitis is an inflammation of the brain parenchyma. In the USA, by estimation, 20,000 cases occur every year. A variety of cognitive deficits may persist after the acute stage, and they are often the sole cause of disability. Recent literature demonstrates the heterogeneity of both amnestic disorders and the outcome following encephalitis. Herpes simplex virus is the most commonly recognised single aetiology of sporadic encephalitis and it may be the cause of the most severe symptoms. Antiviral medication, however, seems to have improved the cognitive outcome when compared to the historical, untreated cases. The cognitive sequelae following herpes simplex virus encephalitis (HSVE) are best known and most commonly described, e.g., in textbooks, but they do not represent the typical symptomatology of encephalitis in general. Much less is unfortunately known about other types of encephalitis, those that account perhaps up to 80% of all cases, where both mild and severe defects have been observed. This article summarises the current knowledge.

Depressive symptoms following herpes simplex encephalitis--an underestimated phenomenon?

OBJECTIVE

In view of the herpes simplex virus' neurotropism for the limbic system and the temporal lobe, little is known about potential negative effects of this necrotizing encephalitis on affective functioning and health-related quality of life (HRQoL) after recovery. We therefore set out to explore an association between herpes simplex virus encephalitis (HSE) and both depressive symptoms and HRQoL.

METHODS

A structured telephone interview was conducted in 26 subjects (F/M=10/16; age at follow-up, 49.3+/-15.0 years; range, 29-80) at a mean time interval of 5.2+/-3.1 years (range, 1-11) after their initial diagnosis of HSE. WHO-5 Well-Being Index (WHO-5) was used as screening instrument for depression, and Short Form-12 was used as HRQoL instrument. We also determined the spatial extent of morphologic abnormalities on magnetic resonance imaging (MRI).

RESULTS

Ten of the interviewees (38.5%) had a WHO-5 score below 13, which is considered indicative of a depressive disorder. Accordingly, concerning their HRQoL, patients felt more impaired by affective than by physical symptoms. MRI ratings and WHO-5 score were not correlated.

CONCLUSIONS

While this pilot study does not allow to establish a causal relationship with focal brain damage, findings suggest both a high frequency of depressive symptoms and a low quality of life with respect to mental health following HSE. These results should be confirmed by a prospective trial.

Cognitive outcome in acute sporadic encephalitis

Acute encephalitis is an inflammation of the brain parenchyma. In the United States, 20,000 cases occur yearly. A variety of cognitive deficits, often the sole cause of disability, may persist after the acute stage. Still, infectious diseases tend to be covered only briefly in neuropsychological handbooks. Recent literature demonstrates the heterogeneity of both amnestic disorders and the outcome following encephalitides. Herpes Simplex virus (HSV), the most common single etiology of sporadic encephalitis, usually causes the most severe symptoms. Modern antiviral medication, however, seems to improve the cognitive outcome. Much less is known about non-HSV encephalitides, where both mild and severe defects have been observed. This article summarizes the current knowledge and also calls upon a more active neuropsychological research in the area.

Rehabilitation outcomes in encephalitis--a retrospective study 1990-1997

BACKGROUND

Encephalitis is an uncommon clinical entity compared to traumatic brain injury, and stroke. Many encephalitis survivors have disabling sequelae. There is scant information in the literature addressing outcome following inpatient rehabilitation for encephalitis. Further, it is unclear which of these patients will benefit from acute in-patient rehabilitation.

PURPOSE

The purposes of this study are to (1) describe the outcome following in-patient rehabilitation in a cohort of patients with encephalitis, and (2) develop preliminary criteria to guide the selection of patients with encephalitis who may benefit from inpatient rehabilitation.

METHOD

The demographic, clinical, functional (functional independence measure-FIM) and neuro-psychological data were retrospectively abstracted for eight subjects with a clinical diagnosis of encephalitis aged 5 to 75 years, who were admitted to a brain injury rehabilitation unit between 1990 and 1997.

RESULTS

In the eight subjects, the mean age was 38 years, mean acute hospital stay (ALOS) was 40.3 days, and mean rehabilitation length of stay (RLOS) was 75.9 days. Mean admission FIM (AFIM) was 40.1, mean discharge FIM (DFIM) was 69.9. Mean FIM gain was 29.8 and mean FIM efficiency was 0.39. Adult subjects with an AFIM > 30 at 5 weeks from onset of illness (n = 4) had a FIM LOS efficiency of 0.64 and all four were discharged home. None of the adult subjects with an AFIM < 30 at 5 weeks from onset of illness (n = 3, FIM efficiency = 0.14) were discharged home. A child with an AFIM < 30 (n = 1) had a FIM LOS efficiency of 1.24, made good recovery and was discharged home. FIM LOS efficiency of 0.64 in encephalitis is less, as compared to traumatic brain injury (TBI -1.27) and stroke (1.06).

CONCLUSIONS

The results of this study showed that, although subjects with encephalitis make functional gains in rehabilitation, the rate of recovery varies and is generally less than that for TBI and stroke. The study also suggests that FIM scores can be used for screening adult patients after encephalitis for admission to inpatient rehabilitation. Adult patients with an AFIM > 30, 5 weeks post onset of illness are likely to make reasonable progress and be discharged home. If replicated, these results suggest that despite low AFIM scores at 5 weeks from onset of illness (AFIM < 30), children may still make good progress and should be given a trial of in-patient rehabilitation.