Institute for Medical Research and Occupational Health
Abstract
Normal flexion of the fingers involves an involuntary contraction of the pronator and lumbrical muscle. In individuals whose profession involves constant flexing of the fingers those muscles become hypertrophied, impinging on the carpal tunnel. The narrowing of the carpal tunnel yields well to ultrasonography. The objective of this investigation was to find an ultrasonographic index of occupational carpal tunnel syndrome. Thus »Index M« denotes the variation obtained in the »M Space« before and after flexion-extension of the fingers. The study included 45 subjects performing tasks which involved the risk of cumulative trauma disorders. The subjects were tested using the electromyography and ultrasonography. The method was based on relation between the decrease in conduction of the median nerve measured by electromyography and the ultrasonographically measured variation of »M Space« in terms of sensitivity and specificity. The sensitivity of ultrasonography was 85%, as it confirmed the pathologic findings determined by electromyography (»M Index« positive) in twenty-two out of 26 hands, but the specificity was not statistically significant. Ultrasonography seems to have found very important application as a screening technique in occupational medicine. It is non-invasive, sensitive, easily repeated, and costs little.Normalna fleksija prstiju uključuje i nekontroliranu kontrakciju pronatora i lumbrikalnog mišića. U osoba čija profesija uključuje opetovano stiskanje prstiju ovi mišići hipertrofiraju i blokiraju karpalni tunel. Sužavanje karpalnog tunela može se utvrditi ultrazvukom. Svrha je ovog rada bila utvrditi objektivni indeks sindroma karpalnog tunela s pomoću ultra zvuka. Tako »Indeks M« označuje varijacije u ultra zvučno-anatomskom »M prostoru« prije i nakon fleksije i ekstenzije prstiju. U istraživanje je uključeno 45 ispitanika koji su obavljali rizični posao što može dovesti do kumulativnih traumatskih poremećenja. Ispitanici su testirani elektromiografski i ultrazvučno. Metoda se zasniva na odnosu između smanjenja brzine provođenja impulsa nervusa medianusa elektromiografski. Ultrazvučno je mjerena varijacija »M-prostora« u smislu utvrđivanja osjetljivosti i specifičnosti. Od 26 patoloških elektromiografskih nalaza ultrazvučno je patološki nalaz potvrđen u 22 ruke. Čini se stoga da ultrazvuk ima vrlo važno mjesto u izdvajanju mogućih bolesnika u rizičnim skupinama, posebice stoga jer je neinvazivna, osjetljiva, ponovljiva i jeftina tehnika
