Vascular parkinsonism and dementia in a CADASIL case with intact nigrostriatal dopaminergic system

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukencephalopathy (CADASIL) is responsible for up to 5% of cerebral small vessel diseases manifesting mostly between the age of 40 and 60 years irrespective of vascular risk factors. The clinical spectrum includes migraine, recurrent subcortical strokes, cognitive decline with a subcortical type of dementia, and mood disorders as the most frequent psychiatric manifestations. A 55-year old male presented to our department with a two year history of progressive immobility, cognitive decline, and urinary incontinence. On examination, the patient showed an atypical parkinsonian syndrome that was not responsive to levodopa (UPDRS III: 45 points) and a moderate dementia (MMSE: 14 points). Brain magnetic resonance imaging suggested small vessel disease. Brain glucose metabolism investigated by positron emission tomography (18F-FDG-PET) was decreased in the temporal cortices, both thalami, and in the left striatum. Striatal dopamine transporter and dopamine D2/D3 receptor binding (123I-FP-CIT- and 123I-IBZM-SPECT) indicated functional integrity of the nigrostriatal dopaminergic system as described for vascular parkinsonism. Electron microscopic evaluation of a skin biopsy was consistant with the diagnosis of CADASIL. This case report indicates that presentation of an atypical parkinsonian syndrome together with normal results of dopamine transporter and dopamine D2/D3 receptor imaging point towards pathology outside the dopaminergic system of the basal ganglia. In such patients with small vessel disease CADASIL should be considered despite vascular risk factors.