Related Experiment Videos
[Non-herpetic acute limbic encephalitis]
1First Department (Neurology) of Internal Medicine, Kurume University School of Medicine.
Abstract:
We reported four cases of acute encephalitis, in which MRI abnormalities localized in the limbic system. In the four cases, fever and consciousness disturbance were commonly found and convulsive seizures appeared in three. Within 10 days, their consciousness level became clear, but severe amnestic syndrome remained as sequela. Cerebrospinal fluid (CSF) at the acute stage revealed mild lymphocytic pleocytosis and elevated protein. MRI revealed abnormal signal intensities in both hippocampi and amygdaloid bodies, although CT scans were normal. Herpes simplex encephalitis selectively affects one or both temporal lobes and the limbic system, But our cases spared the temporal lobes. Additionally, serum and CSF antibody titers by CF and ELISA for herpes simplex virus (HSV) were within normal range from the acute to convalescent stages. Neither HSV type 1 and 2 DNA genomes by sensitive PCR-hybridization method were detected in CSF taken from the acute stage of all four cases. On the other hand, paraneoplastic limbic encephalitis is known as a subacute encephalitis predominantly involving the limbic system. MRI shows high signal intensities on T2-weighted in both medial temporal lobes. In our cases, this type of limbic encephalitis was excluded because of the acute onset and lack of malignancy. Accordingly, our four cases are regarded as non-herpetic acute limbic encephalitis. Several Japanese similar cases have been reported. Further etiological studies should be performed.
Insights
Four patients experienced acute limbic encephalitis with MRI abnormalities but negative herpes simplex virus tests. Despite rapid recovery of consciousness, severe memory loss persisted, indicating a distinct non-herpetic cause.
Area of Science:
- Neurology
- Infectious Diseases
- Neuroimaging
Background:
- Acute encephalitis can present with limbic system involvement.
- Differentiating causes of limbic encephalitis is crucial for prognosis and treatment.
Observation:
- Four cases of acute encephalitis showed MRI abnormalities localized to the limbic system.
- Patients presented with fever, consciousness disturbance, and seizures, followed by residual amnestic syndrome.
- Cerebrospinal fluid revealed mild lymphocytic pleocytosis and elevated protein.
Findings:
- MRI revealed signal abnormalities in hippocampi and amygdalae, distinguishing from typical herpes simplex encephalitis which affects temporal lobes.
- Herpes simplex virus (HSV) testing (antibody titers, PCR) was negative in all cases.
- Paraneoplastic limbic encephalitis was excluded due to acute onset and absence of malignancy.
Implications:
- These cases represent non-herpetic acute limbic encephalitis, distinct from HSV or paraneoplastic causes.
- The findings highlight the need for further etiological research into this specific encephalitis subtype.
- Understanding non-herpetic limbic encephalitis is vital for accurate diagnosis and management of memory deficits.