Retrospektive Untersuchung der Aussagekraft sonographisch ermittelter Nervenwurzeldurchmesser im Rahmen der Polyneuropathie-Diagnostik vor dem Hintergrund einer neuroforaminalen Enge

Nervenwurzeln verlassen den Spinalkanal paarig über die Foramina intervertebralia (Neuroforamina). Durch meist degenerative Veränderung der Wirbelsäule kann es zu Einengungen der Foramina kommen, welche sich mittels bildgebender Verfahren wie der CT- oder der MRT-Untersuchung darstellen lassen. Die Nervenwurzeln selbst sind mit Hilfe der Sonographie gut darstellbar und in ihrer Größe erfassbar. Im Rahmen der Polyneuropathie-Diagnostik hat die Ultraschalluntersuchung der Nerven einen wichtigen Stellenwert eingenommen. Der Begriff der Polyneuropathie bezeichnet eine heterogene Gruppe verschiedener Erkrankungen, die mit einer generalisierten Schädigung der peripheren Nerven einhergeht. Insbesondere demyelinisierende Polyneuropathien gehen gehäuft mit einer Verdickung von Nerven einher, die mit Hilfe der Sonographie detektiert werden kann. Der Untersuchung der zervikalen Nervenwurzeln kommt besondere Bedeutung zu, da Schwellungen in diesen proximalen Nervenabschnitten Hinweise speziell auf entzündliche Polyneuropathien wie das Guillain-Barré-Syndrom oder die CIDP liefern können. In dieser Arbeit wurde der Fragestellung nachgegangen, ob eine mittels MRT oder CT festgestellte Einengung des Neuroforamens mit einer im Ultraschall erfassbaren Verdickung der Nervenwurzel einhergeht und dies somit das Kriterium der Nervenwurzelverdickung im Rahmen der PNP-Diagnostik beeinträchtigen kann. Weiterhin sollten verschiedene Polyneuropathien hinsichtlich ihrer Nervenwurzeldurchmesser verglichen und auf einen möglichen Einfluss einer begleitenden neuroforaminalen Einengung untersucht werden

Intermittent Theta-Burst Transcranial Magnetic Stimulation Alters Electrical Properties of Fast-Spiking Neocortical Interneurons in an Age-Dependent Fashion

Modulation of human cortical excitability by repetitive transcranial magnetic stimulation (rTMS) appears to be in part related to changed activity of inhibitory systems. Our own studies showed that intermittent theta-burst stimulation (iTBS) applied via rTMS to rat cortex primarily affects the parvalbumin-expressing (PV) fast-spiking interneurons (FSIs), evident via a strongly reduced PV expression. We further found the iTBS effect on PV to be age-dependent since no reduction in PV could be induced before the perineuronal nets (PNNs) of FSIs start to grow around postnatal day (PD) 30. To elucidate possible iTBS-induced changes in the electrical properties of FSIs and cortical network activity during cortical critical period, we performed ex vivo—in vitro whole-cell patch clamp recordings from pre-labeled FSIs in the current study. FSIs of verum iTBS-treated rats displayed a higher excitability than sham-treated controls at PD29–38, evident as higher rates of induced action potential firing at low current injections (100–200 pA) and a more depolarized resting membrane potential. This effect was absent in younger (PD26–28) and older animals (PD40–62). Slices of verum iTBS-treated rats further showed higher rates of spontaneous excitatory postsynaptic currents (sEPSCs). Based on these and previous findings we conclude that FSIs are particularly sensitive to TBS during early cortical development, when FSIs show an activity-driven step of maturation which is paralleled by intense growth of the PNNs and subsequent closure of the cortical critical period. Although to be proven further, rTMS may be a possible early intervention to compensate for hypo-activity related mal-development of cortical neuronal circuits

Gerechte Gesellschaft

Witten U, Härtig J, Kürzinger K, eds. Gerechte Gesellschaft. Religion betrifft uns. 2021;(5)

Intermittent theta-burst transcranial magnetic stimulation alters electrical properties of fast-spiking neocortical interneurons in an age-dependent fashion

Modulation of human cortical excitability by repetitive transcranial magnetic stimulation (rTMS) appears to be in part related to changed activity of inhibitory systems. Our own studies showed that intermittent theta-burst stimulation (iTBS) applied via rTMS to rat cortex primarily affects the parvalbumin-expressing (PV) fast-spiking interneurons (FSIs), evident $\it via$ a strongly reduced PV expression. We further found the iTBS effect on PV to be age-dependent since no reduction in PV could be induced before the perineuronal nets (PNNs) of FSIs start to grow around postnatal day (PD) 30. To elucidate possible iTBS-induced changes in the electrical properties of FSIs and cortical network activity during cortical critical period, we performed $\textit {ex vivo—in vitro}$ whole-cell patch clamp recordings from pre-labeled FSIs in the current study. FSIs of verum iTBS-treated rats displayed a higher excitability than sham-treated controls at PD29–38, evident as higher rates of induced action potential firing at low current injections (100–200 pA) and a more depolarized resting membrane potential. This effect was absent in younger (PD26–28) and older animals (PD40–62). Slices of verum iTBS-treated rats further showed higher rates of spontaneous excitatory postsynaptic currents (sEPSCs). Based on these and previous findings we conclude that FSIs are particularly sensitive to TBS during early cortical development, when FSIs show an activity-driven step of maturation which is paralleled by intense growth of the PNNs and subsequent closure of the cortical critical period. Although to be proven further, rTMS may be a possible early intervention to compensate for hypo-activity related mal-development of cortical neuronal circuits