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[Proton MR spectroscopy findings in herpes simplex encephalitis]
M Hitosugi1, M Ichijo, Y Matsuoka
1Department of Internal Medicine, Kawasaki Municipal Hospital.
Abstract:
Localized proton magnetic resonance spectroscopy (1H-MRS) was conducted in two patients with herpes simplex virus type I encephalitis (HSE). MR spectra of bilateral temporal lobes were acquired by the single voxel method using 1.5T unit. Peaks indicating N-acetyl aspartate (NAA), choline (Cho) and creatine including phosphocreatine (Cr) were identified and ratios of NAA/Cr and Cho/Cr were calculated. These ratios were compared with those of the contralateral side showing normal MRI findings and also with the control spectra obtained from normal volunteers. Three abnormal findings were observed in the spectra of the patients suffering from HSE; 1. significant reduction of the NAA/Cr ratio at the involved temporal lobe, 2. mild reduction of the NAA/Cr ratio at the normal temporal lobe, and 3. elevation of the Cho/Cr ratio at the bilateral lobes, but more significant on the involved sides. These results indicated that neural loss and gliosis occurred in the contralateral area with normal MR images as well as the involved hemisphere. We concluded that 1H-MRS is able to show the specific histological findings of herpes simplex encephalitis. This is the first report assessing 1H-MRS for patients with HSE in Japan.
Insights
Proton magnetic resonance spectroscopy (1H-MRS) can detect neural loss and gliosis in herpes simplex virus encephalitis (HSE) patients. This technique reveals specific histological changes even in unaffected brain areas, aiding HSE diagnosis.
Area of Science:
- Neurology
- Radiology
- Biochemistry
Background:
- Herpes simplex virus type I encephalitis (HSE) is a severe neurological condition.
- Accurate diagnosis and assessment of brain involvement are crucial for effective treatment.
Observation:
- Localized proton magnetic resonance spectroscopy (1H-MRS) was performed on two HSE patients.
- MR spectra of temporal lobes were analyzed using a 1.5T unit, focusing on N-acetyl aspartate (NAA), choline (Cho), and creatine (Cr) levels.
Findings:
- Reduced NAA/Cr ratio observed in both affected and contralateral temporal lobes, indicating neural loss and gliosis.
- Elevated Cho/Cr ratio detected bilaterally, more pronounced in affected areas, suggesting ongoing cellular processes.
- 1H-MRS identified specific metabolic changes characteristic of HSE, even in regions with normal MRI appearance.
Implications:
- 1H-MRS is a valuable tool for detecting and characterizing histological changes in HSE.
- This technique can reveal subclinical brain involvement, aiding in early diagnosis and management of HSE.
- Findings suggest 1H-MRS can differentiate HSE from other neurological conditions by showing specific metabolic profiles.