Disruption of nigrostriatal and cerebellothalamic pathways in dopamine responsive Holmes' tremor.

Holmes' tremor is an unusual combination of rest, postural and kinetic tremor of the extremities. Medical treatment of this condition still remains unsatisfactory. The case of a 20-year-old female patient is reported who developed right-sided Holmes' tremor 9 months after a left-sided, cavernoma induced midbrain/pontine haemorrhage at the age of 16 years. Beta-CIT single photon emission computed tomography revealed abolished dopamine transporter activity in the left basal ganglia and striatum, in accordance with missing ipsilateral tegmento-frontal connectivity (medial forebrain bundle), demonstrated by diffusion tensor MRI. Tractography showed reduced fibre connectivity of the superior and middle cerebellar peduncles on the lesioned side. Administration of pramipexole and L-DOPA led to a clinically significant reduction in tremor severity. In conclusion, our results support the notion that Holmes' tremor was a result of diminished striatal dopaminergic input in our patient.