Aberrant resting-state oscillatory brain activity in Parkinson's disease patients with visual hallucinations: An MEG source-space study.

To gain insight into possible underlying mechanism(s) of visual hallucinations (VH) in Parkinson's disease (PD), we explored changes in local oscillatory activity in different frequency bands with source-space magnetoencephalography (MEG). Eyes-closed resting-state MEG recordings were obtained from 20 PD patients with hallucinations (Hall+) and 20 PD patients without hallucinations (Hall-), matched for age, gender and disease severity. The Hall+ group was subdivided into 10 patients with VH only (unimodal Hall+) and 10 patients with multimodal hallucinations (multimodal Hall+). Subsequently, neuronal activity at source-level was reconstructed using an atlas-based beamforming approach resulting in source-space time series for 78 cortical and 12 subcortical regions of interest in the automated anatomical labeling (AAL) atlas. Peak frequency (PF) and relative power in six frequency bands (delta, theta, alpha1, alpha2, beta and gamma) were compared between Hall+ and Hall-, unimodal Hall+ and Hall-, multimodal Hall+ and Hall-, and unimodal Hall+ and multimodal Hall+ patients. PF and relative power per frequency band did not differ between Hall+ and Hall-, and multimodal Hall+ and Hall- patients. Compared to the Hall- group, unimodal Hall+ patients showed significantly higher relative power in the theta band (p = 0.005), and significantly lower relative power in the beta (p = 0.029) and gamma (p = 0.007) band, and lower PF (p = 0.011). Compared to the unimodal Hall+, multimodal Hall+ showed significantly higher PF (p = 0.007). In conclusion, a subset of PD patients with only VH showed slowing of MEG-based resting-state brain activity with an increase in theta activity, and a concomitant decrease in beta and gamma activity, which could indicate central cholinergic dysfunction as underlying mechanism of VH in PD. This signature was absent in PD patients with multimodal hallucinations.

Not the number but the location of lymph nodes matters for recurrence rate and disease-free survival in patients with differentiated thyroid cancer.

BACKGROUND: Several Japanese studies have focused on identifying prognostic factors in patients with positive lymph nodes to predict recurrence rate and disease-free survival (DFS). However, different treatment protocol is followed in Japan compared with the European and American approach. This study was designed to investigate whether the number and/or location of lymph nodes predicts prognosis in patients with DTC treated with total thyroidectomy, lymph node dissection, and postoperative radioactive iodine ablation. METHODS: All 402 patients who were treated at the Department of Nuclear Medicine between 1998 and 2010 for DTC were reviewed. Patients were treated with (near) total thyroidectomy, lymph node dissection on indication, and postoperative I-131 ablation. Median follow-up was 49 (range, 10-240) months. Outcome measures were recurrence rate, disease-free survival, and mean time to recurrence. RESULTS: Ninety-seven patients had proven lymph node metastases. Recurrence rate was significantly higher in patients with positive lymph nodes in the lateral compartment vs. patients with lymph node metastasis in the central compartment (60 vs. 30%, p = 0.007). Disease-free survival and mean time to recurrence also were significantly shorter (30 vs. 52 months, p = 0.035 and 7 vs. 44 months, p = 0.004, respectively). The number of lymph nodes and extranodal growth were not significantly associated with the outcome measures used. CONCLUSIONS: The location of positive lymph nodes was significantly correlated with the risk of recurrence and a shorter DFS. Hence, the TNM criteria are useful in subdividing patients based on risk of recurrence and DFS.