[Transient splenial lesion in influenza A H1N1 2009 infection]

Reversible splenial lesion syndrome associated with lobar pneumonia: Case report and review of literature

BACKGROUND

Reversible splenial lesion syndrome (RESLES) is a rare clinico-radiological disorder with unclear pathophysiology. Clinically, RESLES is defined as reversible isolated splenial lesions in the corpus callosum, which can be readily identified by magnetic resonance imaging (MRI) and usually resolve completely over a period of time. RESLES could be typically triggered by infection, antiepileptic drugs (AEDs), poisoning, etc. More factors are increasingly recognized.

METHODS AND RESULTS

We reported herein an 18-year-old female patient with lobar pneumonia who developed mental abnormalities during hospitalization. An isolated splenial lesion in the corpus callosum was found by head MRI and the lesion disappeared 15 days later. Based on her clinical manifestations and radiological findings, she was diagnosed with lobar pneumonia associated RESLES. We further summarize the up-to-date knowledge about the etiology, possible pathogenesis, clinical manifestations, radiological features, treatment, and prognosis of RESLES.

CONCLUSION

This report contributes to the clinical understanding of RESLES which may present with mental abnormalities after infection. The characteristic imaging of reversible isolated splenial lesions in the corpus callosum was confirmed in this report. The clinical manifestations and lesions on MRI could disappear naturally after 1 month without special treatment.

Mild encephalopathy with reversible splenial lesion in a patient with influenza A infection--first report in an adult patient in the USA

We present a case of a 51-year-old man with panhypopituarism who developed clinically mild encephalopathy with a lesion in the splenium of the corpus callosum, in the setting of acute influenza A infection. The patient's initial presentation included hypernatraemia due to pre-existing iatrogenic central diabetes insipidus. Despite adequate treatment of hypernatraemia, his course was complicated by otherwise unexplained mild encephalopathy. Brain MRI revealed a diffusion restricted lesion in the splenium of the corpus callosum. This presentation was consistent with mild encephalopathy with reversible splenial lesion (MERS). The patient subsequently tested positive for influenza A. This is the first reported case of MERS syndrome due to influenza A infection in an adult patient in the USA. Mild encephalopathy associated with influenza A infection and a reversible splenial lesion of the corpus callosum has a favourable prognosis and resolves spontaneously.

Neurological events related to influenza A (H1N1) pdm09

OBJECTIVES

To review neurological complications after the influenza A (H1N1) pdm09, highlighting the clinical differences between patients with post-vaccine or viral infection.

DESIGN

A search on Medline, Ovid, EMBASE, and PubMed databases using the keywords “neurological complications of Influenza AH1N1” or “post-vaccine Influenza AH1N1.”

SETTING

Only papers written in English, Spanish, German, French, Portuguese, and Italian published from March 2009 to December 2012 were included.

SAMPLE

We included 104 articles presenting a total of 1636 patient cases. In addition, two cases of influenza vaccine-related neurological events from our neurological care center, arising during the period of study, were also included.

MAIN OUTCOME MEASURES

Demographic data and clinical diagnosis of neurological complications and outcomes: death, neurological sequelae or recovery after influenza A (H1N1) pdm09 vaccine or infection.

RESULTS

The retrieved cases were divided into two groups: the postvaccination group, with 287 patients, and the viral infection group, with 1349 patients. Most patients in the first group were adults. The main neurological complications were Guillain-Barre syndrome (GBS) or polyneuropathy (125), and seizures (23). All patients survived. Pediatric patients were predominant in the viral infection group. In this group, 60 patients (4.7%) died and 52 (30.1%) developed permanent sequelae. A wide spectrum of neurological complications was observed.

CONCLUSIONS

Fatal cases and severe, permanent, neurological sequelae were observed in the infection group only. Clinical outcome was more favorable in the post-vaccination group. In this context, the relevance of an accurate neurological evaluation is demonstrated for all suspicious cases, as well as the need of an appropriate long-term clinical and imaging follow-up of infection and post-vaccination events related to influenza A (H1N1) pdm09, to clearly estimate the magnitude of neurological complications leading to permanent disability.

Neurologic complications of influenza

Neurologic complications associated with influenza infection represent rare, but often underappreciated, manifestations of both seasonal and global pandemic influenza. Seizures are the most common neurologic complication, occurring as febrile seizures, as exacerbations in patients with epilepsy, or as symptoms of other influenza-induced neurologic disorders. Encephalopathy is the second most common neurologic complication associated with influenza. A wide spectrum of conditions ranging from coma with severe long-term morbidity or mortality and more mild altered mental states that resolve with minimal-to-no sequelae have been reported. Other less common neurologic complications that have been described include stroke, focal neurologic deficits, Guillain-Barré syndrome, acute disseminated encephalomyelitis, and transverse myelitis.