Longitudinal MR imaging and proton MR spectroscopy in herpes simplex encephalitis.

Longitudinal MR imaging and proton MR spectroscopy were performed in an 11 year-old female case of herpes simplex encephalitis with a complete recovery. On MR imaging, the white matter lesions, which could be seen in the subacute stage, but not in the acute or chronic stage, might represent edema due to postinfectious neuroallergic phenomena. Proton MR spectroscopy revealed marked reduction of the NAA/Cr ratio in the chronic stage, which increased gradually to within normal range in a year.