Abnormal multifocal cerebral blood flow on Tc-99m HMPAO SPECT in a patient with anti-NMDA-receptor encephalitis

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-aspartate receptor (NMDA-R) encephali-tis has been related with teratomas of the ovary in youngwomen. However, this syndrome is non-paraneoplastic inabout 40% of patients, particularly in the youngest patients[1, 3]. This encephalitis is associated with antibodies againstthe NMDA-R NR1 and NR2 subunits. The clinical pictureincludes movement disorders (dystonia, orolingual dyski-nesias, chewing movements, myoclonias,…), decreasedlevel of consciousness, seizures, central hypoventilation andautonomic disturbances. Frequently it is preceded by psy-chiatric symptoms such as changes of mood, behavior andpersonality, or acute psychosis.Brain MRI is normal or with mild changes in mostpatients. To date, scarce data from functional neuroimagingstudies [4] or MR spectroscopy are available. Few neuro-pathological cases have been described [2, 6, 7].We present a patient with anti-NMDA-R encephalitiswith a previously unreported abnormal multifocal cerebralblood flow on Tc-99m HMPAO SPECT.A 14-year-old girl was admitted to the ICU for an acutepsychiatric episode that developed 48 h after an upperrespiratory tract infection. She showed agitation, auditoryand visual hallucinations and aberrant behaviour. A con-ventional neurological examination, CT of the brain andfunduscopy were normal. A lumbar tap yield a colourlessCSF with 140 lymphocytes/ml and a normal glucose andprotein level. PCR for HSV DNA and cytology were nor-mal or negative.In the following days she worsened, developing a gen-eralized dystonia, severe facial grimacing and oculogyriccrisis with a decreased level of consciousness. Autonomicsymptoms were present with hypertensive crisis, tachy-cardia and hypersalivation. The patient did not developcentral hypoventilation. She showed generalized seizuresand was treated with phenytoin.Two gadolinium-enhanced brain MRI were normal(Fig. 1). Several EEGs showed continuous 2.5–3.5 Hz slowwaves without spikes. Brain Tc-99m HMPAO SPECTimages showed multiple focal areas of increased radiotraceruptake in both striatum and cerebral cortex more intense inthe frontal lobes (Fig. 1). Antibodies to NR1/NR2 hetero-mers of the NMDA receptor were found in CSF (immuno-logical studies performed by Drs F. Graus and A. SaizNeurology Service, Hospital Clinic, Universitat de Barce-lona). Ovarian teratoma or other tumors were not identifiedwith repeated specifically oriented CT, MRI, or ultrasound.The patient did not improve after one high dose steroidcourse. A dramatic recovery was observed with the admin-istration of IVIg at standard doses. Repeated brain-Tc-99mHMPAO-SPECT showed a near complete normalization.Brain MR Spectroscopy was performed after resolution of