Thalamic white matter macrostructure and subnuclei volumes in Parkinson's disease depression

Depression is a common non-motor feature of Parkinson's disease (PD) which confers significant morbidity and is challenging to treat. The thalamus is a key component in the basal ganglia-thalamocortical network critical to the pathogenesis of PD and depression but the precise thalamic subnuclei involved in PD depression have not been identified. We performed structural and diffusion-weighted imaging (DWI) on 76 participants with PD to evaluate the relationship between PD depression and grey and white matter thalamic subnuclear changes. We used a thalamic segmentation method to divide the thalamus into its 50 constituent subnuclei (25 each hemisphere). Fixel-based analysis was used to calculate mean fibre cross-section (FC) for white matter tracts connected to each subnucleus. We assessed volume and FC at baseline and 14-20 months follow-up. A generalised linear mixed model was used to evaluate the relationship between depression, subnuclei volume and mean FC for each thalamic subnucleus. We found that depression scores in PD were associated with lower right pulvinar anterior (PuA) subnucleus volume. Antidepressant use was associated with higher right PuA volume suggesting a possible protective effect of treatment. After follow-up, depression scores were associated with reduced white matter tract macrostructure across almost all tracts connected to thalamic subnuclei. In conclusion, our work implicates the right PuA as a relevant neural structure in PD depression and future work should evaluate its potential as a therapeutic target for PD depression.

Carotid artery stenosis, an underestimated cause of stroke recurrence in patients with ischaemic monocular visual loss

INTRODUCTION

Isolated monocular ischaemic events are thought to be low risk for stroke recurrence. In the presence of carotid stenosis however, the risks should not be treated similarly and surgical intervention should be considered at an early stage. The aim of this study was to determine the vascular risk profile and stroke recurrence in patients with ischaemic monocular visual loss.

METHODS AND METHODS

Consecutive records for all patients with monocular ischaemia were reviewed from January 2014 to October 2016. Stroke, transient ischaemic attack or monocular ischaemia recurrence within 90 days were recorded. Carotid stenosis was assessed with duplex ultrasound, computed tomography or magnetic resonance angiography.

RESULTS

In total, 400 patients presented with monocular ischaemia; 391 had carotid imaging (97.8%). Causality was symptomatic carotid stenosis ≥ 50% in 53 (13.6%), including carotid stenosis ≥ 70% in 31 (7.9%). Patients with permanent visual loss (n = 131) were more likely to have significant stenosis compared with patients with transient visual loss (n = 260), 19.8% compared with 10.4% (P = 0.012). Recurrent stroke, transient ischaemic attack or monocular ischaemia within 90 days after presentation occurred in three patients (5.7%) in the carotid stenosis group, compared to three (0.9%) who did not have stenosis (P = 0.035). Age, male sex and hypertension were associated with carotid stenosis but hypercholesterolaemia, diabetes and smoking were not.

CONCLUSIONS

Carotid stenosis ≥ 50% is present in patients with ocular ischaemia in approximately 20% of those with persistent visual loss and in 10% with transient visual loss. Those with carotid stenosis have a higher risk of stroke recurrence and should be considered urgent surgical intervention as other forms of stroke.