MORPHOLOGICAL-CHANGES ELICITED IN SKELETAL-MUSCLE BY A ND-YAG LASER SCALPEL AND ELECTROCAUTERY DURING SURGICAL REDUCTION OF THE HUMAN TONGUE

A Nd:YAG laser scalpel was used for the surgical reduction of a human hyperplastic tongue. This instrument combines a fine cutting precision with haemostatic properties, whereby loss of blood is minimized and t he surgeon's field of view unimpeded by flooding from the damaged capi llary bed. The coagulative properties of Nd:YAG laser light are, howev er, insufficient to effect blood flow stasis in larger calibre vessels (arteries > 2 mm; veins > 3-5 mm), such as those located at the base of the tongue. For this purpose, bipolar diathermy (electrocautery) wa s employed. The ultrastructural changes incurred by skeletal muscle fi bres using these two 'heat' sources were compared. The damage profile elicited using each modality was similar: coagulation of myofilamentou s proteins leads to destruction of fibrillar architecture with concomi tant loss of periodic banding; on moving away from the wound margin, c haracteristic features are gradually restored. As the severity of thes e heat-induced effects decreases, there is a corresponding increase in superimposed dislocation and tearing phenomena induced by post-treatm ent swelling.