[A case of herpes simplex encephalitis with noticeable findings of SPECT].

A 51-year-old man was admitted to our hospital because of fever, general fatigue and disturbance of consciousness. Neurological findings included disturbed consciousness, stiff neck and positive Kernig's sign. He was diagnosed as having herpes simplex encephalitis with HSV-DNA in the cerebrospinal fluid. MRI showed a lesion with low signal intensity in T1-weighted image and high signal intensity in T2-weighted image in the right temporal lobe. The single photon emission CT (SPECT) study showed discordance of 99mTc ethyl cysteinate dimer-SPECT (ECD-SPECT) and N-isopropyl-p-[123I]-iodoamphetamine-SPECT (IMP-SPECT). Decreased signal of ECD in the lesion where IMP uptake was increased could be due to decreased esterase activity. This report suggests that ECD-SPECT could fail to detect cerebral blood flow in the lesion with severe metabolic damage.