Acute disseminated encephalomyelitis following influenza vaccination

Recurrent Episodes of Acute Hiccups With Influenza

Hiccups are a common reflex mechanism and can be classified based on the duration of symptoms. While hiccups are mostly benign and self-limiting, persistent hiccups can cause functional limitations. Hiccups can also be the presenting symptom of an underlying illness. We present the case of a patient who had two distinct episodes of acute hiccups after influenza. We highlight the mechanism behind the hiccups reflex and describe various causes of hiccups, including infections. The varying modalities through which viral infections can lead to hiccups are also described.

Identifying and reducing risks of neurological complications associated with vaccination

Vaccines protect against many infectious diseases, including some that can directly or indirectly cause nervous system damage. Serious neurological consequences of immunization are typically extremely rare, although they have the potential to jeopardize vaccination programmes, as demonstrated most recently during the COVID-19 pandemic. Neurologists have an important role in identifying safety signals at population and individual patient levels, as well as providing advice on the benefit-risk profile of vaccination in cohorts of patients with diverse neurological conditions. This article reviews the links between vaccination and neurological disease and considers how emerging signals can be evaluated and their mechanistic basis identified. We review examples of neurotropic infections with live attenuated vaccines, as well as neuroimmunological and neurovascular sequelae of other types of vaccines. We emphasize that such risks are typically dwarfed by neurological complications associated with natural infection and discuss how the risks can be further mitigated. The COVID-19 pandemic has highlighted the need to rapidly identify and minimize neurological risks of vaccination, and we review the structures that need to be developed to protect public health against these risks in the future.

Neurological complications of influenza vaccination: navigating the spectrum with a focus on acute disseminated encephalomyelitis (ADEM)

Introduction

Acute disseminated encephalomyelitis (ADEM) is a rare neurological disorder characterized by inflammation in the brain and spinal cord. This systematic review aims to investigate the potential association between ADEM and influenza vaccination by analyzing relevant case reports. ADEM is traditionally thought to be a monophasic condition, predominantly affecting children, often following viral illnesses or immunizations. Recent attention has focused on a possible link between ADEM and influenza vaccination, prompting the need for a thorough investigation.

Methods

The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the AMSTAR2 (A MeaSurement Tool to Assess systematic Reviews 2) guidelines. Electronic searches were conducted on PubMed, Cochrane Library, and clinicaltrials.gov databases, spanning up to August 2023. Inclusion criteria encompassed full-text articles in English, observational studies, case reports, and case series providing comprehensive details for confirming clinical diagnoses of ADEM following influenza vaccination. Data were extracted, including demographic information, vaccination details, clinical symptoms, diagnostic evaluations, treatment modalities, and outcomes. Quality assessment was performed using the Joanna Briggs Institute (JBI) Critical Appraisal tool.

Results

A total of 23 cases of ADEM following influenza vaccination were identified from 19 included articles. The mean age of affected individuals was 40.2 years (±25.7) with 60.8% being male. Common presenting symptoms included muscle weakness (52.1%), urinary abnormalities (30.4%), altered consciousness (26%), and sensory disturbances (26%). Neurological examination revealed findings such as extensor plantar reflex (positive Babinski sign) in 26%, hyperreflexia in 30.4%, and generalized hyporeflexia in 13% of the cases. Diagnostic evaluations involved MRI, showing multiple hyperintense lesions in cerebral hemispheres (43.4%), subcortex (60.8%), and spinal cord (39.1%). Cerebrospinal fluid analysis indicated elevated white blood cell count in 69.5% of cases, with lymphocytic pleocytosis in 52.1%. Oligoclonal bands were reported positively in 8.6% of cases. Treatment approaches varied, with intravenous methylprednisolone being the most common (39.1%). Out of the 23 cases, two (8.6%) patients had a fatal outcome, while the rest showed clinical improvement with complete or partial resolution of symptoms. Persisting symptoms included numbness in the lower extremities (8.6%) and impaired ability to walk after 10 months (4.3%).

Conclusion

While the association between ADEM and influenza vaccination is rare, healthcare professionals should remain vigilant and consider patients' vaccination history, particularly following an influenza immunization. This systematic review highlights the clinical manifestations, diagnostic tools, treatment approaches, and outcomes of ADEM cases post-influenza vaccination. Further research is essential to understand this association and improve clinical decision-making, ensuring the safety and efficacy of immunization programs.

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA): past, present, and future implications

Adjuvants, as the name indicates, are adjoined material aimed to assist in functioning as when added to vaccines they are meant to boost the effect and strongly stimulate the immune system. The response of the immune system can be unpredictable, and the autoimmune/inflammatory syndrome induced by adjuvants (ASIA) was developed to address possible adverse reactions of an autoimmune and inflammatory type that may be caused by adjuvants. While ASIA, as a syndrome, was coined and defined in 2011; reports describing patients with vague and nonspecific clinical symptoms following vaccinations appeared much earlier. In other words, ASIA came to define, arrange, and unite the variety of symptoms, related to autoimmunity, caused not by the vaccine itself, rather by the adjuvant part of the vaccine such as aluminum, among others. Accordingly, the introduction of ASIA enabled better understanding, proper diagnosis, and early treatment of the disorder. Furthermore, ASIA was shown to be associated with almost all body systems and various rheumatic and autoimmune diseases such as systemic lupus erythematosus, antiphospholipid syndrome, and systemic sclerosis. In addition, the correlation between COVID-19 and ASIA was noticed during the pandemic. In this review, we summarized the reported effects of adjuvants and medical literature before and after ASIA was defined, the several ways ASIA can manifest and impact different systems of the body, and the incidences of ASIA during the COVID-19 pandemic. It is important to clarify, that vaccines are among, if not the, most effective means of fighting infectious diseases however, we believe that vaccines manufacturing is not above criticism, particularly when it comes to added substances possessing a risk of side effects.

Vaccines and Autoimmunity-From Side Effects to ASIA Syndrome

Since vaccines are in fact manufactured chemical compounds such as drugs, the appearance of side effects following their use is not surprising. Similarly, as the main goal of vaccines is to stimulate the immune system bringing out the production of protective antibodies, autoimmune-related side effects as a consequence of increased immune activity do not seem irrational. Fortunately, the rate of such side effects is low; however, the importance of reporting adverse events following vaccinations, understanding the mechanisms behind their appearance, making early diagnosis, and appropriate treatment cannot be overemphasized. In fact, autoimmune-related side effects of vaccines, particularly those based on adjuvants, were reported long before the introduction of the autoimmune/inflammatory syndrome induced by adjuvants (ASIA). Nevertheless, ASIA gathered and united the side effects of vaccines under one title, a step which helped organize the research and call for better immune stimulators than adjuvants. New technologies and methods of making vaccines were clearly noticed during the pandemic of COVID-19 after the introduction of mRNA-based vaccines. In our current paper, we introduce the notion of side effects to vaccines, particularly those of autoimmune nature, the mechanisms of ASIA, and the main vaccines linked with the syndrome including the recent COVID-19 vaccines. The transition from side effects to ASIA is the main idea behind our work.

Acute disseminated encephalomyelitis and routine childhood vaccinations - a self-controlled case series

Acute disseminated encephalomyelitis (ADEM) is an autoimmune, central nervous system demyelinating disorder that follows antecedent immunologic challenges, such as infection or vaccination. This study aimed to investigate the potential association between routine childhood vaccinations and ADEM. Children under 7 years of age admitted to the two tertiary level pediatric hospitals in Victoria, Australia with ADEM from 2000-2015 had their clinical information linked to vaccination records from the Australian Childhood Immunization Register. Chart review was undertaken utilizing the Brighton Collaboration ADEM criteria. The self-controlled case-series (SCCS) methodology was employed to determine the relative incidences of ADEM post-vaccination in two risk intervals: 5-28 days and 2-42 days. Forty-six cases were eligible for SCCS analysis with a median age of 3.2 years. Of the forty-six cases, three were vaccine proximate cases and received vaccinations 23, 25 and 28 days before ADEM onset. Two vaccine proximate cases received their 4-year-old scheduled vaccinations (MMR and DTPa-IPV) and one vaccine proximate case the 1-year old scheduled vaccinations (MMR and Hib-MenC). The relative incidence of ADEM during the narrow and broad risk intervals were 1.041 (95% CI 0.323-3.356, p = 0.946) and 0.585 (95% CI 0.182-1.886, p = 0.370) respectively. Sensitivity analyses did not yield any substantial deviations. These results do not provide evidence of an association between vaccinations routinely provided to children aged under 7 years in Australia and the incidence of ADEM. However, these results should be interpreted with caution as the number of ADEM cases identified was limited and further research is warranted.

Unusual Neurological Manifestation of Proton Pump Inhibitor: A Case Report of Acute Disseminated Encephalomyelitis and Severe Hyponatremia After Brief Use of Proton Pump Inhibitor

Hyponatremia is commonly reported after the use of proton pump inhibitors (PPI). While omeprazole is most likely to cause hyponatremia, almost all the PPIs have been reported to cause hyponatremia. The underlying mechanism of PPI-induced hyponatremia is a syndrome of inappropriate antidiuretic hormone (SIADH) secretion which leads to hyponatremia. The hyponatremia can develop with only a few days of exposure to PPI. We present a case of a 56-year-old previously healthy female who was prescribed omeprazole for trivial acid reflux symptoms when she presented to the emergency room for evaluation of generalized weakness. She was discharged home from the emergency room after clinical evaluation as she had essentially normal lab work including a negative COVID PCR test. She subsequently developed progressive weakness of extremities and slurred speech over the next three days. She returned back to the emergency room and was found to have profound hyponatremia with MRI evidence of acute disseminated encephalomyelitis (ADEM). She was treated with hypertonic saline to correct hyponatremia and omeprazole was discontinued. The patient also received pulse dose steroids with improvement in her symptoms.

Complete Oculomotor Palsy after Influenza Vaccination in a Young Healthy Adult: A Case Report

Influenza vaccines are known to have a few neurological complications, such as Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, and acute disseminated encephalomyelitis. However, oculomotor palsy caused by influenza vaccination is extremely rare. We present a case report of a 25-year-old woman without any medical history who developed complete oculomotor palsy 2 weeks after influenza vaccination. Other possible causes of oculomotor nerve palsy, such as stroke, compressive lesions, infections, and autoimmune disorders, were eliminated by blood tests, cerebrospinal fluid examination, and imaging studies. Hence, influenza vaccine was considered as the likely cause.

Bilateral thalamic lesions in a patient with probable acute disseminating encephalomyelitis: a case report

BACKGROUND

Bilateral thalamic lesions are rare. Here, we describe a case of probable acute disseminating encephalomyelitis (ADEM) with symmetrical bilateral thalamic lesions.

CASE PRESENTATION

An 85-year-old man presented with weakness of the lower limbs and urinary retention for 1 day, soon followed by coma. He had an H1N1 influenza vaccination 3 months ago. A lumbar puncture showed positive oligoclonal bands and negative results for anti-AQP4 antibodies. A head MRI demonstrated focal symmetrical bilateral thalamic lesions. An MRI of the thoracic spinal cord showed longitudinally extensive lesions in the spinal cord. He was diagnosed with probable ADEM. Despite being treated with IVIG, the patient remained unconscious and died a month later from pneumonia.

CONCLUSIONS

In cases with bilateral thalamic lesions, the possibility of ADEM should be considered. The characteristics of the thalamic lesions and imaging findings in other parts of the brain or spinal cord should be taken into account in association with the clinical and laboratory information in making a correct diagnosis.

Vaccine-Associated Neurological Adverse Events: A Case Report and Literature Review

Vaccination is an effective strategy to reduce the burden of preventable illness. However, many clinical reports revealed that various vaccinations may associate with neurological disorders, mainly including autoimmune disease, febrile seizure, and vaccine-associated paralytic poliomyelitis (VAPP). Although more and more reports revealed that part of the above post-vaccine neurological disorders is not directly related to vaccination, it may be merely a coincidence. However, these reports may increase the hesitancy on vaccination for the public population and influence the coverage of vaccination. In this report, we described a child with acute flaccid paralysis possibly caused by a poliovirus vaccine. To provide feasible ways to realize or reduce the risk of neurological adverse events caused by vaccines, we further provide a mini-review of the literature of vaccination associated with neurological adverse events. This revealed that oral poliomyelitis vaccine use exclusively and type 2 serotype poliomyelitis vaccine virus were the risk factors for VAPP. The combination vaccine was associated with an increased risk of ADEM and FS following immunization when compared with the administration of vaccines separately. Even though cases have been reported that vaccination may be a trigger of anti-NMDARe and GBS, there is no direct evidence to prove that vaccination increased the risk of GBS and anti-NMDARe.

Acute Disseminated Encephalomyelitis After Influenza Vaccination: A Case Report

Acute disseminated encephalomyelitis is an inflammatory demyelinating disease of the central nervous system that has been associated with influenza immunization, but only a few cases related to vaccination for influenza have been reported. Acute disseminated encephalomyelitis developed in a 42-year-old woman within 3 weeks of receiving the seasonal influenza vaccine. She had 80% recovery after 3 months of treatment with methylprednisolone. Although cases of acute disseminated encephalomyelitis after vaccination for influenza are rare, enough of them have occurred that critical care nurses should be aware of the possibility. Early treatment can prevent serious residual signs and symptoms; therefore, correct and quick diagnosis is important. Medical history obtained from patients with central nervous system problems should include history of recent vaccinations.

Vaccine-associated inflammatory diseases of the central nervous system: from signals to causation

PURPOSE OF REVIEW

As the most cost-effective intervention in preventive medicine and as a crucial element of any public health program, vaccination is used extensively with over 90% coverage in many countries. As approximately 5-8% of the population in developed countries suffer from an autoimmune disorder, people with an autoimmune disease are most likely to be exposed to some vaccines before or after the disease onset. In fact, a number of inflammatory disorders of the central nervous system have been associated with the administration of various vaccines. These adverse events, be they spurious associations or genuine reactions to the vaccine, may lead to difficulties in obtaining public trust in mass vaccination programs. There is, thus, an urgent need to understand whether vaccination triggers or enhances autoimmune responses.

RECENT FINDINGS

By reviewing vaccine-associated inflammatory diseases of the central nervous system, this study describes the current knowledge on whether the safety signal was coincidental, as in the case of multiple sclerosis with several vaccines, or truly reflected a causal link, as in narcolepsy with cataplexy following pandemic H1N1 influenza virus vaccination.

SUMMARY

The lessons learnt emphasize a central role of thorough, ideally prospective, epidemiological studies followed, if the signal is deemed plausible or real, by immunological investigations.

Autoimmune/inflammatory syndrome induced by adjuvants (Shoenfeld’s syndrome) – An update

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA) has been widely described in many studies conducted thus far. The syndrome incorporates five immune-mediated conditions, all associated with previous exposure to various agents such as vaccines, silicone implants and several others. The emergence of ASIA syndrome is associated with individual genetic predisposition, for instance those carrying HLA-DRB1*01 or HLA-DRB4 and results from exposure to external or endogenous factors triggering autoimmunity. Such factors have been demonstrated as able to induce autoimmunity in both animal models and humans via a variety of proposed mechanisms. In recent years, physicians have become more aware of the existence of ASIA syndrome and the relationship between adjuvants exposure and autoimmunity and more cases are being reported. Accordingly, we have created a registry that includes at present more than 300 ASIA syndrome cases that have been reported by different physicians worldwide, describing various autoimmune conditions induced by diverse adjuvants.

In this review, we have summarized the updated literature on ASIA syndrome and the knowledge accumulated since 2013 in order to elucidate the association between the exposure to various adjuvant agents and its possible clinical manifestations. Furthermore, we especially referred to the relationship between ASIA syndrome and systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS).

Pandemic H1N1 Vaccination and Incidence of Acute Disseminated Encephalomyelitis in Manitoba

Background: An increased incidence of hospital admissions coded as acute disseminated encephalomyelitis (ADEM) was noted in Winnipeg, Manitoba, Canada, during the second wave of the influenza pandemic from October 2009 to March 2010. However, it was not clear whether this was due to heightened awareness of potential neurological complications of influenza or influenza vaccination or an actual increase in the number of cases. Methods: We extracted data from the charts of 139 patients hospitalized with an International Classification of Diseases-10 discharge code indicating ADEM (G04.0) or unspecified noninfectious encephalitis or myelitis (G04.8, G04.9) between January 2006 and December 2012. Clinical and laboratory data were reviewed by a neurologist, and diagnoses were determined using the Brighton criteria. Results: Over the entire study period, there were 22 cases of ADEM. During the peak pandemic period (April-December 2009), seven patients were hospitalized with ADEM, corresponding to a rate of 7.8/million/year; 4.7 (95% confidence interval: 1.9-11.4) times higher than the rate before or after the pandemic period. Only one patient with ADEM had received the monovalent A(H1N1)pdm09 vaccine within 12 weeks of hospitalization. Conclusions: We have found an increased incidence of ADEM during the pandemic period that may be related, at least in part, to the increased incidence of influenza during that period. However, there was no temporal relationship with the administration of A(H1N1)pdm09 or seasonal influenza vaccines. Our study provides reassurance that use of these vaccines was not associated with increased risk of ADEM.

Acute disseminated encephalomyelitis with severe neurological outcomes following virosomal seasonal influenza vaccine

Acute disseminated encephalomyelitis (ADEM) is an inflammatory, usually monophasic, immune mediate, demyelinating disease of the central nervous system which involves the white matter. ADEM is more frequent in children and usually occurs after viral infections, but may follow vaccinations, bacterial infections, or may occur without previous events. Only 5% of cases of ADEM are preceded by vaccination within one month prior to symptoms onset. The diagnosis of ADEM requires both multifocal involvement and encephalopathy and specific demyelinating lesions of white matter. Overall prognosis of ADEM patients is often favorable, with full recovery reported in 23% to 100% of patients from pediatric cohorts, and more severe outcome in adult patients. We describe the first case of ADEM occurred few days after administration of virosomal seasonal influenza vaccine. The patient, a 59-year-old caucasic man with unremarkable past medical history presented at admission decreased alertness, 10 days after flu vaccination. During the 2 days following hospitalization, his clinical conditions deteriorated with drowsiness and fever until coma. The magnetic resonance imaging of the brain showed multiple and symmetrical white matter lesions in both cerebellar and cerebral hemispheres, suggesting demyelinating disease with inflammatory activity, compatible with ADEM. The patient was treated with high dose of steroids and intravenous immunoglobulin with relevant sequelae and severe neurological outcomes.

The spectrum of post-vaccination inflammatory CNS demyelinating syndromes

A wide variety of inflammatory diseases temporally associated with the administration of various vaccines, has been reported in the literature. A PubMed search from 1979 to 2013 revealed seventy one (71) documented cases. The most commonly reported vaccinations that were associated with CNS demyelinating diseases included influenza (21 cases), human papilloma virus (HPV) (9 cases), hepatitis A or B (8 cases), rabies (5 cases), measles (5 cases), rubella (5 cases), yellow fever (3 cases), anthrax (2 cases),meningococcus (2 cases) and tetanus (2 cases). The vast majority of post-vaccination CNS demyelinating syndromes, are related to influenza vaccination and this could be attributed to the high percentage of the population that received the vaccine during the HI1N1 epidemia from 2009 to 2012. Usually the symptoms of the CNS demyelinating syndrome appear few days following the immunization (mean: 14.2 days) but there are cases where the clinical presentation was delayed (more than 3 weeks or even up to 5 months post-vaccination) (approximately a third of all the reported cases). In terms of the clinical presentation and the affected CNS areas, there is a great diversity among the reported cases of post-vaccination acute demyelinating syndromes. Optic neuritis was the prominent clinical presentation in 38 cases, multifocal disseminated demyelination in 30, myelitis in 24 and encephalitis in 17. Interestingly in a rather high proportion of the patients (and especially following influenza and human papiloma virus vaccination-HPV) the dominant localizations of demyelination were the optic nerves and the myelon, presenting as optic neuritis and myelitis (with or without additional manifestations of ADEM), reminiscent to neuromyelitic optica (or, more generally, the NMO-spectrum of diseases). Seven patients suffered an NMO-like disease following HPV and we had two similar cases in our Center. One patient with post-vaccination ADEM, subsequently developed NMO. Overall, the risk of a demyelinating CNS disease following vaccination, although non-negligible, is relatively low. The risk of onset or relapse of CNS demyelination following infections against which the vaccines are aimed to protect, is substantially higher and the benefits of vaccinations surpass the potential risks of CNS inflammation. This does not in any way exempt us from“learning” the lessons taught by the reported cases and searching new and safer ways to improve vaccination techniques and increase their safety profile.

Acute disseminated encephalomyelitis onset: evaluation based on vaccine adverse events reporting systems

OBJECTIVE

To evaluate epidemiological features of post vaccine acute disseminated encephalomyelitis (ADEM) by considering data from different pharmacovigilance surveillance systems.

METHODS

The Vaccine Adverse Event Reporting System (VAERS) database and the EudraVigilance post-authorisation module (EVPM) were searched to identify post vaccine ADEM cases. Epidemiological features including sex and related vaccines were analysed.

RESULTS

We retrieved 205 and 236 ADEM cases from the EVPM and VAERS databases, respectively, of which 404 were considered for epidemiological analysis following verification and causality assessment. Half of the patients had less than 18 years and with a slight male predominance. The time interval from vaccination to ADEM onset was 2-30 days in 61% of the cases. Vaccine against seasonal flu and human papilloma virus vaccine were those most frequently associated with ADEM, accounting for almost 30% of the total cases. Mean number of reports per year between 2005 and 2012 in VAERS database was 40±21.7, decreasing after 2010 mainly because of a reduction of reports associated with human papilloma virus and Diphtheria, Pertussis, Tetanus, Polio and Haemophilus Influentiae type B vaccines.

CONCLUSIONS

This study has a high epidemiological power as it is based on information on adverse events having occurred in over one billion people. It suffers from lack of rigorous case verification due to the weakness intrinsic to the surveillance databases used. At variance with previous reports on a prevalence of ADEM in childhood we demonstrate that it may occur at any age when post vaccination. This study also shows that the diminishing trend in post vaccine ADEM reporting related to Diphtheria, Pertussis, Tetanus, Polio and Haemophilus Influentiae type B and human papilloma virus vaccine groups is most likely not [corrected] due to a decline in vaccine coverage indicative of a reduced attention to this adverse drug reaction.

Acute disseminated encephalomyelitis onset: evaluation based on vaccine adverse events reporting systems

OBJECTIVE

To evaluate epidemiological features of post vaccine acute disseminated encephalomyelitis (ADEM) by considering data from different pharmacovigilance surveillance systems.

METHODS

The Vaccine Adverse Event Reporting System (VAERS) database and the EudraVigilance post-authorisation module (EVPM) were searched to identify post vaccine ADEM cases. Epidemiological features including sex and related vaccines were analysed.

RESULTS

We retrieved 205 and 236 ADEM cases from the EVPM and VAERS databases, respectively, of which 404 were considered for epidemiological analysis following verification and causality assessment. Half of the patients had less than 18 years and with a slight male predominance. The time interval from vaccination to ADEM onset was 2-30 days in 61% of the cases. Vaccine against seasonal flu and human papilloma virus vaccine were those most frequently associated with ADEM, accounting for almost 30% of the total cases. Mean number of reports per year between 2005 and 2012 in VAERS database was 40±21.7, decreasing after 2010 mainly because of a reduction of reports associated with human papilloma virus and Diphtheria, Pertussis, Tetanus, Polio and Haemophilus Influentiae type B vaccines.

CONCLUSIONS

This study has a high epidemiological power as it is based on information on adverse events having occurred in over one billion people. It suffers from lack of rigorous case verification due to the weakness intrinsic to the surveillance databases used. At variance with previous reports on a prevalence of ADEM in childhood we demonstrate that it may occur at any age when post vaccination. This study also shows that the diminishing trend in post vaccine ADEM reporting related to Diphtheria, Pertussis, Tetanus, Polio and Haemophilus Influentiae type B and human papilloma virus vaccine groups is most likely not [corrected] due to a decline in vaccine coverage indicative of a reduced attention to this adverse drug reaction.

Acute disseminated encephalomyelitis following seasonal influenza vaccination in an elderly patient

Although such occurrences are rare, it should be recognized that certain vaccines might trigger serious neurological immune phenomena such as Guillain-Barre syndrome, seizures, cranial neuropathy, and acute disseminated encephalomyelitis (ADEM). Here we report on an elderly woman with ADEM following seasonal influenza vaccination who recovered after plasma exchange.