Zusammenfassung
Das durch Kathetermessungen belegte Phänomen eines Druckanstiegs innerhalb des Karpaltunnels während Handgelenkextension und -flexion wurde auf seine morphologische Korrelation bei gesunden Probanden (n=15) und Patienten mit Karpaltunnelsyndrom (n = 15) untersucht. Eigene Messungen mittels Magnetresonanztomographie (MRT) ergaben, daß sich die Querschnittsfläche des Karpaltunnels während der Handgelenkflexion auf Höhe des Os pisiforme und des Os hamatum und während der Extension auf Höhe des Os pisiforme verkleinert. Dies erklärt die Druckerhöhung innerhalb des Karpaltunnels während Extension und Flexion und die konsekutive nachteilige Auswirkung auf den Nervus medianus. Die Schwellung des Nervus medianus proximal und die Abflachung des Nervus medianus distal im Karpaltunnel sowie die Palmardeviation des Ligamentum carpi transversum proximal und distal im Karpaltunnel waren bei Patienten mit Karpaltunnelsyndrom signifikant ausgeprägter als bei Gesunden (p<0,05 bis p<0,001). In postoperativen Untersuchungen drei Monate nach Dekompression bei 13 Patienten, die keine klinischen Beschwerden mehr angaben, ging die distale Abflachung des Nervus medianus in 94% zurück. Die Signalerhöhung des Nervus medianus in T2-gewichteten Aufnahmen nahm in 67% der Fälle ab, während die motorische Nervenleitgeschwindigkeit sich in diesem Zeitraum nur in 39% normalisierte. Die MRT hat somit eine hohe Wertigkeit für die Diagnose und postoperative Verlaufskontrolle bei Patienten mit Karpaltunnelsyndrom.
Abstract
The morphological correlation of the phenomenon of increased pressure in the carpal tunnel during wrist flexion and extension — as has been proved though measurements using wick-catheters — was studied in healthy subjects (n=15) and symptomatic patients with carpal tunnel syndrome (n=15). Our own measurements using magnetic resonance imaging (MRI) showed that there is a significant reproducible decrease in carpal tunnel diameter when the wrist is held in position of either flexion or extension. During flexion the diameter is decreased at the pisiformes and hamate level as well as it is lowered during extension at the pisiformes level. This might explain the rise in carpal tunnel pressure and thus the consecutive negative influence on the median nerve. Proximal swelling, distal flattening and increased signal intensity of the median nerve as well as the palmar bulging of the flexor retinaculum at the level of the hook of the hamate and at the level of the pisiformes were significantly higher in patients with carpal tunnel syndrom than in normal volunteers (from p<0.05 to p<0.001). In post-operative follow-up examinations of 13 patients with no clinic symptoms the distal flattening of the median nerve normalized in 94% within 3 months. The increased signal of the median nerve on T2-weighted images decreased postoperatively in 2/3 of the patients, whereas the motor latency of the median nerve recovered only in 39% of our patients who had 100% partial or complete clinical benefit. These findings imply that postoperative imaging may be helpful for evaluating the success or failure of surgical treatment.
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Allmann, K.H., Horch, R., Gabelmann, A. et al. Zur Morphologie des Karpaltunnels. Unfallchirurgie 22, 5–11 (1996). https://doi.org/10.1007/BF02627456
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DOI: https://doi.org/10.1007/BF02627456