Dopamine transporter image in CRMP5 associated autoimmune encephalitis

Abstract

CRMP5 is one of onco-neuronal antibodies and CRMP5 associated encephalitis has been rarely reported. Various clinical features including chorea, myelitis, visual symptoms and gait disturbance were found. Neither the target of CRMP5 antibodies has been determined, nor dopamine transporter image was reported yet. We report a CRMP5 associated encephalitis showing a reduced uptake in the striatum using FP-CIT. A 69 years-old man was admitted because of involuntary movement. Ten months prior to admission, he started to complain gait instability & choreic movement in head & both limbs. Administration of haloperidol failed to progression of abnormal involuntary movement. On examination, he showed repetitive neck movement, flexion & extension while he was walking. He also showed slow and wide based gait, together with choreic movement in his right hand. Parkinsonian features other than slowness were not noted. In the CSF, mildly elevated protein, but no pleocytosis was found. CRAM5 antibody was positive. MRI revealed widening of both anterior horns of ventricles and ill-defined signal change involving both caudate nucleus heads. FP-CIT dopamine transporter imaging showed severely decreased uptake in both striatum, more prominent in caudate. This is a first report of CRMP5 associated encephalitis showing reduced uptake in the striatum using FP-CIT. This finding suggests CRMP5 antibody may be associated with pathological process in the presynaptic nigrostriatal system, more in the caudate. Larger studies including postmortem will be needed to explore the target of CRMP5 associated encephalitis.