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A 22-year-old woman was presented with a new onset of seizures after delivering her first child. The headache moderately intense, non-positional, bifrontal, with a throbbing quality after one day. Her pregnancy was unremarkable, and she developed a cough, fever (39.6°) and tachycardia at the time of her delivery. She was also detected with influenza B virus infection on nasopharyngeal swab consistent with respiratory influenza. After seven days, she had generalised convulsions and right elbow flexion and head version to the left.
Which of the following syndrome explains the new onset of seizures and respiratory influenza infection?
Influenza-associated encephalitis (IAE) is a complex neurological syndrome commonly reported in children and is associated with a high degree of morbidity and mortality. The incidence of IAE in adults is rare, with estimated prevalence rates of 0.21 per million population per year. Clinically, it is presented with fever (93%), seizures (27%), and altered mental status (23%) up to 3 weeks followed by respiratory influenza infection. In children, it can be presented with a severe form known as acute necrotising encephalopathy, characterised by symmetric lesions involving the brainstem, thalami, brainstem, corpus callosum and cerebellum. The aetiology of IAE is poorly understood, but it appears to include a hyperactivated cytokine response instead of direct viral invasion. It is supported by the fact that influenza virus may initiate the release of pro-inflammatory cytokines (interleukin-6, soluble tumour necrosis factor) in the brain that stimulates microglia to secrete inflammatory mediators. The inflammatory mediators cause direct neurotoxic effects, the breakdown of the blood-brain barrier and cerebral metabolic derangements.
The diagnosis and management of IAE is challenging due to the lack
of clear diagnostic and clinical criteria. The patients with recent respiratory
influenza infection are often diagnosed of IAE. Differentiating IAE from septic
encephalopathy in patients with sepsis is difficult. The initial examination
includes nasopharyngeal testing for influenza, magnetic resonance imaging (MRI)
of the brain and lumbar puncture.
With an estimated incidence of
0.21 per million population per year the diagnosis and treatment of IAE are
difficult as there is a lack of well-defined diagnostic and clinical criteria.
Treatment with oseltamivir and immunomodulation have been proposed but efficacy
data is lacking.
The patient was suggestive of new focal-onset seizures with secondary generalisation. Her family history was unremarkable with normal development.
Clinical diagnosis:
During her initial physical examination, her blood pressure was reported 175/105 mm Hg and a heart rate was 81 beats per minute. She was alert without acute distress and nuchal rigidity. Funduscopic examination revealed no papilledema. Her verbal fluency decreased with the absence of sensory and visual neglect. She had difficulty in following Luria-3 test. Comprehensive metabolic and coagulation studies were normal. Initial laboratory studies indicated proteinuria and a neutrophil-predominant leukocytosis.
Confirmatory diagnosis:
Cognitive examination indicated dysfunction
in the frontal lobe
Luria test showed deficits in motor
planning due to difficulty in performing hand motions
MRI with or without contrast suggested a
T2/fluid-attenuated inversion recovery (FLAIR) hyperintensity in the right
middle frontal gyrus with mild leptomeningeal enhancement
Magnetic resonance venography (MRV) showed
no signs of venous thrombosis
Lumbar puncture and cerebrospinal fluid
analysis (CSF) revealing:
The patient’s clinical presentation confirmed respiratory influenza infection, and MRI abnormalities are consistent with IAE.
The
patient was initially treated with magnesium infusion for 24 hours, resolving
her proteinuria and hypertension. She was also given levetiracetam 500 mg twice
daily for the treatment of seizures. She was treated with a 7-day course of
intravenous acyclovir and also oseltamivir for influenza infection. Her
clinical condition was improved after ten days, and then she was discharged
from the hospital. She was free of seizures with improvement in her cognitive
deficits at follow up examination of 1 and four months. MRI scan showed
improvement of T2/FLAIR hyperintensities after three months.
The current case report presented a rare
case of pregnant women diagnosed with influenza-associated encephalitis (IAE).
It elucidates the diagnosis and management of IAE which is quite challenging.
The initial diagnosis includes nasopharyngeal testing for influenza, MRI brain,
and lumbar puncture. Most of the cases indicate abnormalities in MRI and
constitute T2 hyperintensities in the brainstem, cerebellum, and subcortical
white matter. The evaluation of cerebrospinal fluid (CSF) is also essential;
however, it is positive in 16% of cases. A rise in the influenza antibody
titers have been detected in a few case reports, but its frequency is not
well-established. The management therapies for IAE are not well-organised.
Seizures and cerebral oedema require immediate evaluation and supportive
control. Oseltamivir and immunomodulation therapies have been proposed, but
evidence to depict their efficacy is still lacking.
The diagnosis of IAE should be considered in all patients with encephalitis with recent respiratory illness due to its morbidity and mortality rates.
Neurology May 2018, 90 (18) e1631-e1635
Clinical Reasoning: A 22-year-old postpartum woman with new-onset seizures and headache
Kevin McGehrin et al.
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