July, 1955 P H Y S I O T H E R A P Y Page Three EXPERIENCES WITH ULTRASONICS By R O N A L D R O B IN S-B R O W N E , m .d ., d . p h y s . m e d ., l .m ., m .r .c .s., Johannesburg. Specialist in Physical Medicine, Tara Hospital, Johannesburg, and Germiston Hospital. Reprinted fr o m the “South African M edical Journal," Vol. 29, 26th March, 1955, pages 300—302. IN the past 18 m onths I have personally adm inistered over 3,000 ultrasonic treatm ents using one type o f machine. D uring this period I have received an increasing number o f inquiries o n th e subject. The sym ptom s o f patients referred to th e Specialist in Physical M edicine fall m ainly under a tw ofold classi­ fication, viz. pain an d disability, usually both com plaints are present but sometimes only one. Likewise th e pathology is also tw ofold, viz. traumatic an d rheumatic, often one feature occurring but sometimes both. T he Physical M edicine Specialist, having taken the history from the p atient and m ade his exam ination and pertinent investigations, determines the diagnosis before proceeding to prescribe from the vast arm am antarium at his disposal, which includes various form s o f heat, high- frequency and low-frequency currents, actinotherapy, hydrotherapy, massage, kinesiatrics, spinal traction, inter­ m ittent venous occlusion and occupational therapy. To these form s o f treatm ent is now added—ultrasonics. Historical. D uring 1917 ultrasonics were used experi­ mentally in G erm any and were found to have biological effects.1 L ater, when the country was being ruled by megalomaniacs, it was hailed— as being a w onder cure for m ost conditions—from an ingrowing toenail to an exostosis o f the skull. However m ost w riters seemed to agree th a t it was o f great value in th e treatm ent o f varicose and indolent ulcers. It was then handled in the U .S.A .—probably in too big a way—fo r adverse reports were given stating th at necrosis o f tissue and irreversible changes in nerve tissue had been produced. Thereafter it was tried in G reat B ritain, where it was stated to be useful in the treatm ent o f ankylos­ ing spondylitis. Nature and Generation. U ltrasound consists o f mecha­ nical vibrations beyond the range o f hum an audition and therefore o f a frequency o f m ore th a n 20,000 per second. T he particular m achine I used propagates 800,000 cycles per second o f continuous unmodified oscillations. These are generated by passing a high frequency cu rren t o n to a n atural quartz crystal which consequently vibrates and produces ultrasound. T he penetration varies according to the type o f tissue it has to traverse but the intensity decreases to ab o u t i its value at a depth o f 1— l i inches. I t is completely absorbed in air o r gas. T he transducer applicator I use has an area o f 7 sq. cm. all o f which radiates ultrasound. Use in Medicine The effects2 o f ultrasound are: 1. Mechanical. These include the disintegration of crystalline solids, and sometimes o f colloidal particles, w ith their em ulsification; th e coagulation o f fogs, smoke and some emulsions; and the degassing o f liquids. C avi­ tation results when the disruptive forces engendered break through cohesive bands between molecules o f a liquid, a gas, o r even certain colloids o r solids. T he cavities are immediately collapsed by th e succeeding compressive phase o f th e sound vibration plus atm ospheric pressure. 2. Thermal. H eat is generated in any m edium by ultrasound, the am ount depending on the energy absorbed. The am ount o f heat produced an d th e region o f maximum heating are influenced by the n atu re o f the medium, the presence o f dispersive elements, colloidal particles and pre­ cipitates, and reflection a t interfaces o f m atter. H igher sound-frequencies generate m ore heat per u n it o f energy and time. I f cavitation occurs it is accom panied by con­ siderable heat production. T he heat released in living tissues is localized an d there is norm ally rapid rem oval by th e circulation, conduction an d radiation. A m ple evidence o f dam age to tissues has been dem onstrated when ultrasound in overdoses is applied to epiphyses, fascia and muscle. 3. Chemical. These are oxidation, luminescence, de­ polym erization, hydrolysis and inversion o f sugar. 4. Biological. T he following are some o f the actions and theories regarding this aspect o f u ltrasound: (а) I t produces heat3 (this I found to be very mild, rath er a w arm th). (б) I t acts as a m icro-m assage4 (I believe this to be one o f its functions). (c) There is a subsequent hyperaem ia and vaso­ dilation.6 (d) I t has a sedative action on neural tissues,6 relieving pain either directly o r via the sym pathetic o r p ara­ sym pathetic systems (I found this to be so). (