Levodopa-responsive Holmes’ Tremor Caused by a Single Inflammatory Demyelinating Lesion

BACKGROUND Holmes' tremor is characterized by a combination of rest, postural, and kinetic tremor that is presumably caused by interruption of cerebello-thalamo-cortical and nigrostriatal pathways. Medical treatment remains unsatisfactory. CASE REPORT A 16-year-old girl presented with Holmes' tremor caused by a transient midbrain abnormality on magnetic resonance imaging (MRI). To explore the discrepancy between persistent tremor and resolved MRI changes, we performed dopamine transporter single-photon emission computed tomography (DaT-SPECT) with a 123I-ioflupane that revealed nearly absent DaT binding in the right striatum. Levodopa dramatically improved the tremor. DISCUSSION This is only the second report of a transient midbrain MRI abnormality disrupting nigrostriatal pathways. The case highlights the sometimes limited sensitivity of morphologic imaging for identifying the functional consequences of tissue damage and confirms that DaT imaging may serve as a predictor for levodopa responsiveness in Holmes' tremor.