Altered cerebrovenous drainage in patients with migraine as assessed by phase-contrast magnetic resonance imaging.

OBJECTIVE: We aimed to assess whether migraine is associated with changes in the distribution of the venous drainage through primary and secondary pathways by using phase-contrast magnetic resonance imaging (MRI). METHODS: We examined 26 patients (37.3 ± 13.9 years) with recurring migraine headaches and 26 age- and gender-matched controls with no neurologic disease (37.3 ± 13.7 years) on a 3 Tesla MR scanner. A 2D time-of-flight MR-venography of the upper neck region was performed to visualize the venous vasculature. Cine-phase contrast scans with high-velocity encoding were employed to quantify arterial inflow and flow in the primary venous channels (right and left jugular veins), whereas scans with low-velocity encoding were employed to quantify flow in the secondary venous channels (epidural, vertebral, and deep cervical veins). RESULTS: Patients with migraine showed (i) a higher prevalence of dense secondary extracranial venous networks (15 vs. 2, P = 0.00002) and (ii) a significantly larger percentage of venous outflow through secondary channels (10.5% vs. 5.5%; of total cerebral blood flow, P = 0.02). This mainly included drainage through epidural, vertebral, and deep cervical veins. CONCLUSION: Migraine patients showed a significantly larger percentage of venous outflow through secondary channels. The mechanism of this alteration remains to be elucidated. Potential mechanisms include repeated release of vasoactive substances or growth factors.

Mirror movements in healthy humans across the lifespan: effects of development and ageing.

AIM: mirror movements are a transient phenomenon during childhood, which decrease in intensity with motor development. An increasing inhibitory competence resulting in the ability of movement lateralization is thought to be the underlying mechanism. We aimed to quantify unintended mirror movements systematically across the lifespan and to investigate the influences of age, sex, handedness, and task frequency. METHOD: a total of 236 participants (127 females, 109 males; 216 right-handed, 20 left-handed; age range 3-96y, median 25y 8mo) first performed four clinical routine tests while mirror movements were rated by the observer. They were then asked to hold a force transducer in each hand between the thumb and index finger and to perform oscillatory grip force changes in one hand, while the other hand had to prevent the force transducer from dropping. RESULTS: age showed a strong nonlinear effect on the mirror-movement ratio (the amplitude ratio of the mirror and active hand, adjusted by the respective maximum grip force). Initially, there was a steep decline in the mirror-movement ratio during childhood and adolescence, followed by a gradual rise during adulthood. Males had lower mirror-movement ratios than females. The high-frequency condition triggered lower mirror-movement ratios. No significant differences of mirror movements between dominant and non-dominant hand, or left- and right-handed participants, were found. INTERPRETATION: this study provides, for the first time to our knowledge, normative values of mirror movements across the lifespan that can aid differentiation between physiological and pathological mirror movements.

Cranial CT with 64-, 16-, 4- and single-slice CT systems-comparison of image quality and posterior fossa artifacts in routine brain imaging with standard protocols.

Posterior fossa artifacts constitute a characteristic limitation of cranial CT. To identify practical benefits and drawbacks of newer CT systems with reduced collimation in routine cranial imaging, we aimed to investigate image quality, posterior fossa artifacts and parenchymal delineation in non-enhanced CT (NECT) with 1-, 4-, 16- and 64-slice scanners using standard scan protocols. We prospectively enrolled 25 consecutive patients undergoing NECT on a 64-slice CT. Three groups with 25 patients having undergone NECT on 1-, 4- and 16-slice CT machines were matched regarding age and sex. Standard routine CT parameters were used on each CT system with helical acquisition in the posterior fossa; the parameters varied regarding collimation and radiation dose. Three blinded readers independently assessed the cases regarding image quality, infra- and supratentorial artifacts and delineation of brain parenchymal structures on a five-point ordinal scale. Reading orders were randomized. A proportional odds model that accounted for the correlated nature of the data was fit using generalized estimating equations. Posterior fossa artifacts were significantly reduced, and the delineation of infratentorial brain structures was significantly improved with the thinner collimation used for the newer CT systems (p<0.001). No significant differences were observed for midbrain structures (p>0.5). The thinner collimation available on modern CT systems leads to reduced posterior fossa artifacts and to a better delineation of brain parenchyma in the posterior fossa.