Dissociation of 99m Tc-ECD and 99m Tc-HMPAO distributions in herpes simplex encephalitis

Abstract

In herpes simplex encephalitis (HSE), the authors noted an evident dissociation between the 99mTc-ethyl cysteinate dimer (ECD) and 99mTc-d,l-hexamethyl-propylene-amine oxime (HMPAO) single photon emission computed tomographies (SPECTs). The patient was a 5-year-old boy with diffuse type of pontine glioma, which was treated with hyperfractionated radiotherapy. Two weeks after the completion of radiation therapy, a lesion suggesting that of HSE was noted in the right fronto-temporal region on magnetic resonance images. 99mTc-HMPAO SPECT showed an increased accumulation of the tracer in this lesion. On the 99mTc-ECD dynamic SPECT, an exaggerated accumulation of the tracer was noted within 80 s of administration, followed by a rapid drop in the accumulation, resulting in a low accumulation in 10 min. It was assumed that this dissociation was due to the different mechanisms to trap HMPAO and ECD in the brain tissue.

Herpes simplex encephalitis in glioma patients: a challenging diagnosis

“…We conducted a review of the literature and found 14 previously reported cases of HSE in patients with gliomas,6–16 with details reported in online supplementary table S2. Consistently with that found in our series, HSE occurred during different steps of cancer history (in five patients perioperatively,7–9 in six patients during radiotherapy10–14 and in the last three patients within 3 months of its completion6 15 16), and evolution was characterised by high mortality or severe morbidity despite antiviral treatment.…”

Temporal Lobectomy in Acute Complicated Herpes Simplex Encephalitis

“…Short-term follow-up evaluation showed aphasia and motor deficits (19). Another patient responded well to acyclovir but developed aphasia and mild hemiparesis (22). The outcome was not reported for the third patient (17).…”

“…Clinical presentation can be atypical in these cases with absent or mild pleocitosis in cerebrospinal fluid and initial negative findings on neuroimaging (17,19,22). In the few reported cases of HSE in patients with brain tumors, severe complications were fre-quent.…”

“…One died 13 days after starting acyclovir therapy; thus, resistance can be hypothesized (10). Of the three cases reported in children with brainstem gliomas and HSE, all received acyclovir (17,19,22). One patient did not respond initially and foscarnet was tried but not tolerated.…”

Herpes simplex encephalitis and subsequent cytomegalovirus encephalitis after chemoradiotherapy for central nervous system lymphoma: a case report and literature review

“…Several reports have described cases of HSE that occurred after radiotherapy for CNS malignancies, as summarized in Table 1 [8][9][10][11][12][13][14]. In addition to these reports, HSE has been reproducibly observed in other case series of malignant glioma (2/81), medulloblastoma and primitive neuroectodermal tumor (1/14), and primary CNS lymphoma (1/14) receiving chemoradiotherapy [15][16][17].…”