Cognitive Dysfunction in Drug-induced Parkinsonism Caused by Prokinetics and Antiemetics

The use of prokinetics/antiemetics is one of the leading causes of drug-induced parkinsonism (DIP) observed in neurology clinics. Cognitive dysfunction in DIP has recently been recognized, but pathologies related with cognitive dysfunction is unknown. Among our retrospective cohort of 385 consecutive parkinsonian patients enrolled in our parkinsonism registry, 14 patients were identified who satisfied our inclusion criteria: parkinsonism caused by prokinetics/antiemetics, existing T1-weighted 3D volumetric MR images, and normal [18F]-N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane PET scan images. For the comparison of volumetric MR data, 30 age- and sex-matched healthy individuals were included in this study. Among 14 patients with DIP, 4 patients were diagnosed with dementia, and all other patients had mild cognitive impairment (MCI). Comparisons of MR volumetric data between DIP patients with MCI and controls show that cortical gray matter volumes are reduced bilaterally in DIP (P=0.041) without changes in either total white matter volume or total intracranial volume. Among subcortical structures, the volume of the right hippocampus is reduced in DIP patients compared with controls (P=0.011, uncorrected). In DIP, cortical thickness is reduced in the bilateral lingual (P=0.002), right fusiform (P=0.032) and part of the left lateral occipital gyri (P=0.007). Our results suggests that cognitive dysfunction in DIP caused by prokinetics/antiemetics is common. Structural changes in the brain by 3D MRI may be associated with cognitive decline in DIP.

Dopamine transporter imaging in clinically unclear cases of parkinsonism and the importance of Scans Without Evidence of Dopaminergic Deficit (SWEDDs) / Neuroimagem do transportador de dopamina em casos de parkinsonismo clinicamente indefinidos e a importância dos SWEDDs (exames sem evidência de déficit dopaminérgico)

The clinical diagnosis of Parkinson's disease (PD) is susceptible to misdiagnosis, especially in the earlier stages of the disease. Recently, in vivo imaging techniques assessing the presynaptic dopamine transporter (DAT) have emerged as a useful tool in PD diagnosis, improving its accuracy. OBJECTIVE: It was to illustrate the clinical usefulness of a brain single-photon emission computed tomography (SPECT) DAT ligand, and highlight relevant aspects of scans without evidence of dopaminergic deficit (SWEDDs) in this context. CASES: We described four representative patients with clinically unclear parkinsonian syndromes who underwent [99mTc]-TRODAT-1 SPECT and reviewed the clinical implications. CONCLUSION: DAT-SPECT is an important, cost-effective, technique for the differential diagnosis of parkinsonian syndromes. Additionally, SWEDD cases present clinical and paraclinical peculiarities that may retrospectively identify them as essential/dystonic tremor. The lack of histopathological data limits further conclusions.

O diagnóstico clínico da doença de Parkinson (DP) pode estar sujeito a erros especialmente nas fases iniciais da doença. Recentemente, técnicas de imagem in vivo que avaliam o transportador de dopamina pré-sináptico (DAT) surgiram como uma ferramenta empregada no diagnóstico da DP, melhorando sua acurácia. OBJETIVO: Foi demonstrar a utilização clínica de um traçador de tomografia computadorizada por emissão de fóton único (SPECT) e destacar importantes aspectos dos casos de SWEDDs (exames sem evidência de déficit dopaminérgico) neste contexto. CASOS: Descrevemos quatro pacientes representativos de síndromes parkinsonianas clinicamente incertas submetidos a [99mTc]-TRODAT-1 SPECT e revisamos suas implicações. CONCLUSÃO: O DAT-SPECT é uma técnica importante e eficiente para o diagnóstico diferencial das síndromes parkinsonianas. Além disso, os casos de SWEDDs apresentam peculiaridades clínicas e paraclínicas que podem retrospectivamente identificá-los como tremor essencial ou tremor distônico. As conclusões têm alcance limitado pela falta de dados histopatológicos.