Methylphenidate Alters Functional Connectivity of Default Mode Network in Drug-Naive Male Adults With ADHD.

Objective: This study evaluated the hypothesis that methylphenidate immediate release (MPH-IR) treatment would improve Default Mode Network (DMN) within-connectivity. Method: Resting-state functional connectivity of the main nodes of DMN was evaluated in a highly homogeneous sample of 18 drug-naive male adult participants with ADHD. Results: Comparing resting-state functional connectivity functional magnetic resonance imaging (R-fMRI) scans before and after MPH treatment focusing exclusively on within-DMN connectivity, we evidenced the strengthening of functional connectivity between two nodes of the DMN: posterior cingulate cortex (PCC) and left lateral parietal cortex (LLP). Conclusion: Our results contribute to the further understanding on how MPH affects functional connectivity within DMN of male adults with ADHD and corroborate the hypothesis of ADHD being a delayed neurodevelopmental disorder.

Attention deficit/hyperactivity disorder: is there a correlation between dopamine transporter density and cerebral blood flow?

Attention deficit/hyperactivity disorder (ADHD) is one of the most frequent behavioral problems in school-age children. Although the etiology remains unclear, the involvement of the dopaminergic system has been suggested by genetic studies that report an overexpression of the dopamine transporter (DAT) gene. In spite of these abnormalities being directly related to the decrease of dopamine (DA) in the striatum (STR), abnormalities in brain perfusion have also been observed in cortical-subcortical structures. Functional neuroimaging studies have suggested that the DA concentration may cause changes in the cerebral blood flow (CBF). The objective of our study was to evaluate the relationship between DAT density in STR and cortical-subcortical impairment in CBF. Based on the hypothesis that there is a correlation between DA availability and brain perfusion, we postulated that individuals with ADHD, with a higher DAT density in the basal ganglia, will have lower perfusion in the fronto-striatal-cerebellar networks. We used Tc-99m TRODAT-1 SPECT to measure DAT density and Tc-99m ECD SPECT to assess brain perfusion. Ten adolescents diagnosed with ADHD by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria were investigated. Analysis with Statistical Parametric Mapping 5 corrected for multiple comparisons, using small volume correction, showed a significant negative correlation between the DAT density in the STR and CBF in the cingulate gyrus, frontal lobe, temporal lobe, and cerebellum (pFDR <0.01). Our findings suggest that higher DAT density in the STR was associated with a decrease in the regional CBF in the cortical and subcortical attention network.

The surgical management of the sentinel lymph node in cutaneous melanoma might be different when the primary lesion was previously resected with 1 cm margin.

AIM: To simulate the effects of previous wide cutaneous melanoma excision in sentinel lymph node (SLN) biopsy feasibility through a change in the radiotracer injection site. MATERIALS AND METHODS: Thirty-three patients with cutaneous melanoma underwent two preoperatory lymphoscintigraphic studies. In the first, the radiopharmaceutical was injected intradermally 0.3 cm away from the lesion/scar. Dynamic images were acquired to find the SLN. On the following day, the procedure was repeated with the radiopharmaceutical injected 1 cm farther from the previous injection sites. The number of lymph nodes and sites of drainage were compared with the findings of the first study. All the patients underwent SLN biopsy using a gamma probe and patent blue. RESULTS: Seventy-five SLNs were identified with radiopharmaceutical injected at 0.3 cm from the lesion versus 82 SLNs when injected at 1.3 cm. All lymph nodes visualized with close injection were identified with the farther injection. Twenty-seven (81%) patients presented the same number and location of SLNs. Six (19%) patients presented more SLNs with the expanded technique, three patients in the same basin and three in a new lymph node station. All metastatic SLNs were harvested by the two injection techniques. CONCLUSION: The value of the SLN biopsy in patients with cutaneous melanoma is maintained even after the primary lesion has been removed with a margin of up to 1 cm. Some patients might show an increased number of SLNs and some might show drainage to additional lymph node stations.