Heywood V, Synge H, eds. The conservation of medicinal plants. Proceedings of a Conference 21-27 March 1988, Chiang Mai, Thailand. Cambridge: Cambridge University Press, 1991. 7. Famsworth NR, Soejarto DD. Potential consequences of plant extinction in the United States on the current and future availability of prescription drugs. Economic Botany 1985; 39: 231-40. 6. Akerele O,

Principe P. The economic significance of plants and their constituents as drugs. In: Wagner H, Hikino H, Farnsworth NR, eds. Economic and medicinal plant research, vol 3. London: Academic Press, 1989. 9. Russell P. The white hole in time: our future evolution and the meaning of now. London: Aquarian Press, 1992. 8.

10. Pearce DW. An economic approach to saving the tropical forests. London Environmental Economics Centre Paper 90-06. London LEEC, 1991. 11. Fellows LE. Pharmaceuticals from traditional medicinal plants and other species: future prospects. In: Coombes JD, ed. New drugs from natural sources. International Business Communication Technical Series, 1992: 95-102. 12. Patterson W. Are we throwing away the planet’s future? New Scientist November 16, 1991, p 8. 13. Woodwell GM. The warming of the industrialised middle latitudes 1985-2050: causes and consequences. Climatic Change 1989; 15: 31-50. 14. Friends of the Earth. Deserts of trees. London: Friends of the Earth, 1992.


lithotripsy of salivary duct stones

Surgical extirpation of the affected gland has been necessary for cases of sialolithiasis in which the stone cannot be removed by dilatation or dissection of the salivary duct. The ability of the piezoelectric lithotripter to deliver shockwaves to a small focus makes extracorporeal shockwave lithotripsy of salivary gland stones potentially safe. Its safety and efficacy have been assessed in 51 patients with symptomatic solitary salivary stones that could not be removed by conservative measures.

The stones had a median diameter of 8 (range 4-18) mm and were located in the submandibular gland in 69% of patients and in the parotid gland in 31%. A total of 72 shockwave treatment sessions (maximum 3 per patient) were given under continuous sonographic monitoring. In 45 patients (88%) complete fragmentation (fragments ≤ 3 mm) of the concrements was achieved. No patient needed anaesthesia, sedatives, or analgesics. The only untoward effects were localised petechial haemorrhages after 10 (13%) out of 72 treatments and transient swelling of the gland immediately after delivery of shockwave in 2/72 (3%) sessions. 20 weeks after the first session 90% (46/51) of patients were free of discomfort, and 53% (27/51) were stone free. Stone-clearance rate was higher among patients with stones in the parotid gland (81%) than among those with stones of the submandibular gland (40%). Auxiliary measures such as dilatation or dissection of the salivary duct were required only in patients with stones in the submandibular gland (20%). No long-term damage to the treated salivary gland or to adjacent tissue structures was noted during the median follow-up of 9 (1-24) months.

Extracorporeal piezoelectric shockwave therapy seems likely to be a safe, comfortable, and effective minimally-invasive, non-surgical treatment for salivary stones.

Introduction Sialolithiasis is said to affect 12 per 1000 people.’ The stone can induce stasis of the saliva, and painful sialadenitis with bacterial superinfection and abscess formation can result.12 If the stones are close to the orifice of the main salivary duct, extraction after dilatation or dissection of the duct may be possible. If the procedure fails, the only other option has been surgical removal of the entire gland.2,3-1 Extracorporeal shockwave lithotripsy is now much used for the treatment of renal and gallstones. The electrohydraulic and electromagnetic lithotripters, which were the machines first used, delivered shockwaves to a focus too large to be suitable for salivary gland stones. The piezoelectric principle delivers shockwaves to a smaller focus 34 which makes it probably suitable for delivery to salivary gland stones without damaging adjacent tissue. Having investigated the feasibility of fragmenting salivary gland stones in vitro with piezoelectrically generated shockwaves5 and having studied the reactions caused by such waves in the head and neck area in animals,6 we attempted shockwave lithotripsy of symptomatic salivary gland stones in man.7 Here we describe our acute and long-term experience with piezoelectric salivary lithotripsy in the first 51 patients.

Subjects and methods Patients Patients with symptomatic solitary stones in the parotid or submandibular gland were eligible for the study if the stones were judged to be sufficiently distant from the orifice of the duct to make extraction by dilatation or dissection of the duct unlikely to be successful. Patients who had previously undergone salivary duct dissection were excluded because of the possibility of pre-existing stenoses due to scarring. 51 (72%) out of 71 patients with solitary stones referred to lithotripsy were selected; 35 (69%) had stones in the submandibular gland and 16 (31 %) stones in the parotid gland (table). Patients with acute sialadenitis were first treated with antibiotic and anti-inflammatory drugs. Lithotripsy was done electively when the inflammation had settled. ADDRESSES: Department of Oto-Rhino-Laryngology, Head and Neck Surgery (H. Iro, MD, C. Fodra, MD, G Waitz, MD, N Nitsche, MD, H. H. Heinritz, MD); and Department of Medicine (H Th Schneider, MD, J. Benninger, MD, Ch. Ell, MD), University of D-8520 Germany. Erlangen-Nuremberg, Eriangen, Correspondence to Dr H Iro


spatial planes under continuous sonographic monitoring until the salivary gland stone was positioned exactly in the shockwave focus. The rate of shockwave discharge could be varied between 1 and 25 Hz; the pulse energy could be selected over a pressure range from 40 to 150 MPa in the shockwave focus. On the basis of the experience gained from the in-vitro and animal work,5,6 no more than 3000 pulses were applied per treatment session, with the first 500 shockwaves at intensity setting 1, and the remainder at setting 2. The pulse frequency was kept constant, at 1-6 Hz (setting 3). No premedication was given. However, sedatives or analgesics could be given during therapy, if required. Delivery of shockwaves was terminated when the stone was lost sight of on sonography or when sonography suggested that adequate fragmentation had occurred. If the stone was in the parotid duct, patients were given a tooth guard to protect the maxillary molars. Ear plugs were inserted into the external auditory canal of all patients before treatment, to protect the auditory system. If residual fragments were detected sonographically during the follow-up and if the patient had symptoms of obstructive sialadenitis a maximum of two repeat treatments were allowed, 8 and 16 weeks after first therapy. Shockwave therapy was rated as unsuccessful if residual fragments and clinical symptoms persisted after the two repeat treatments. In such cases patients were advised to undergo surgical extirpation of the gland.

Pretreatment and post-treatment investigations Before shockwave treatment and 24 h after lithotripsy all patients underwent-apart from sonographic examination of the affected salivary gland-the following tests: measurement of serum amylase concentration (alpha-amylase), audiography, magnetic resonance tomography of the salivary gland and the adjacent structures (including brain), and electromyography of the facial nerve. Sonographic and clinical follow-up examinations were scheduled for 2, 4, 8,12,16, and 20 weeks after lithotripsy, and thereafter every 6 months for an overall period of 2 years.

Auxiliary post-treatment measures When a large fragment seemed to be stuck in the duct near the ostium, papillotomy and dilatation of the duct were done to facilitate the passage of that fragment and any others distal to it. All patients were advised to encourage salivation (eg, by chewing gum) for 4-6 weeks after lithotripsy.


Sonographic pictures of effect of shockwave fragmentation stone in left


parotid gland.

Before shockwave therapy parotid duct (DCT) is obstructed by a (+ --- +) and enlarged (M MASS = massseter muscle; CAVITAS OR IS= oral cavity). (b) 1 h after lithotripsy with 3000 extracorporeally generated piezoelectric shockwaves, fragmentation indicated by the distinctly enlarged reflex zone (+---+) with dorsal sound extinction; salivary duct is no longer obstructed and not visible on ultrasonography. (c) 4 weeks after lithotripsy, absence of detectable stones.


The 51 patients received a total of 72 extracorporeal shockwave treatment sessions. 36 (70%) patients were treated once, 9 (18%) twice, and 6 (12%) three times. The median number of shockwaves per session was 2100 (range 960-3010) and the median number per patient was 2500

(960-8700) (table).


Piezoelectric lithotripsy A Piezolith 2300 piezoelectric lithotripter (R. Wolf, Knittlingen, was used. The underlying physical principle has been described elsewhere.4,5 The circular opening of the water-filled transducer was covered with a latex membrane to prevent the patient’s head being inadvertently immersed in water. Ultrasound jelly was applied between the latex membrane and the skin overlying the affected salivary gland to prevent energy loss during transduction of the shockwaves to the body. The site of the stone was identified sonographically with one of two real-time B-scanners (4 MHz), which was arranged in line with the longitudinal axis of the transducer. The shockwave emitter was moved along the three


Stone disintegration There were no between stones in the parotid gland and those in the submandibular gland in proportion successfully fragmented (table). Dilatation of the papilla and/or the duct or papillotomy became necessary only for submandibular stones. The number of lithotripsy sessions required was similar for submandibular and parotid stones. In neither gland were there correlations between stone size and stone clearance rates, or between the duration of the salivary stone disorder and stone clearance. The proportion of patients with a parotid calculus symptom free at 4 weeks and at 20 weeks after first lithotripsy was similar to that for patients with a submandibular calculus, but the proportion of patients stone free was higher with parotid stones than with calculus in the submandibular gland (table). All 51

stones were

significant differences

fragmented (figure).



*After 1 st treatment session

In 5 patients with sialolithiasis of the submandibular gland shock-wave therapy was not successful; although stone disintegration occurred in all of them, none of these patients became stone free and all of them had recurrent symptoms, though to a lesser degree than before therapy. 3 of them agreed to removal of the affected gland. None of the 51 patients was lost to follow-up and no stone recurrence was observed over the median follow-up period of 9 months

(range 1-24). Untoward reactions All

patients reported slight sharp pains in the skin overlying the gland to which shockwaves were applied. Patients rated this discomfort as minor and none required anaesthesia, analgesics, or sedatives. Petechiae of the skin were observed after 14% (10/72) of the sessions. Only 2 patients (3%) had transient reactive swelling of the treated salivary gland after lithotripsy; their pain subsided within 48 h with antiphlogistic measures. In no patient did sonography or magnetic resonance tomography show abnormalities after lithotripsy; in particular, there was no evidence of haemorrhage near the treated salivary gland. Alpha-amylase concentrations remained normal. Electromyography did not reveal any damage to the facial nerve, and follow-up audiological examinations did not indicate shockwave-induced hearing

impairment. Discussion Our - findings indicate that

piezoelectrically generated extracorporeal shockwaves can reproducibly and effectively cause the in-vivo fragmentation of salivary gland stones. The physical properties of the piezoelectric generator and the precision with which the site of the stone was identified

than 1000 times that of first-generation electrohydraulic lithotripters4) and a high focal pressure of up to 150 MPa. Even the second-generation electrohydraulic and electromagnetic lithotripters have a focal volume substantially greater than that of the piezoelectric shockwave generator. A large focal zone can mean that shockwaves directed at the salivary glands might damage neighbouring central nervous system structures-animal studies have shown shockwaves intentionally directed at the margin of the orbit close to the parotid gland can cause intracerebral bleeding or necrosis and thus death. Apparently, the shockwaves had been conducted into the cerebrum via the superior orbital fissure.6 None of our patients required analgesics or sedatives, so outpatient therapy and repeat treatments are possible. Stone disintegration was successful in all patients, and 90 % of them became pain free. They have remained symptom free throughout the follow-up, the median period being 9 months. Symptom relief occurred not only in patients with complete stone clearance but also in most of those with residual fragments. Whether symptom relief without stone clearance can be regarded as treatment success must take into account the incidence of symptomatic re-obstructions or the success of repeat treatments. All 4 patients with a parotid stone who received repeat treatments became stone free, whereas stone clearance was achieved in only 1 out of 11patients with a submandibular stone despite a total of 16 repeat treatments. Overall stone clearance was more successful in patients with parotid stones (81 %) than in those with submandibular stones (40%). The reasons for this difference seem to be anatomical and physiological and the greater ease with which the site of the stone can be identified sonographically in the parotid gland. The duct of the parotid gland follows a descending path and has no sharp bends, whereas the duct of

the submandibular gland follows an ascending course and has a kink at the rear rim of the floor of the mouth. Furthermore, the secretion of the submandibular gland is rich in mucus and this is distinctly more viscous than the serous parotid saliva.1-3 In contrast to lithotripsy of gallbladder stones, salivary stone clearance always bore a close temporal relation to shockwave treatment. All patients with complete stone clearance became stone free within 4 weeks after the first or last lithotripsy. For salivary calculi stone clearance is defined as the spontaneous discharge of fragments, if necessary with the help of auxiliary measures such as dilatation or dissection of the duct, but without long-term and expensive oral

chemolitholysis. Surgical extirpation of the gland, which has often been the only therapeutic option to date for salivary duct stones distant from the ostium,3,8 carries risks such as intubation anaesthesia lasting several hours, the possibility of injury to the facial nerve, and the postoperative occurrence of Frey’s syndrome.9-11 Damage to the lingual nerve, hypoglossal nerve, and the oral branch of the facial nerve are the main hazards associated with surgical extirpation of the submandibular gland. 10-12 Extracorporeal salivary lithotripsy now provides another therapeutic option that carries few risks and causes little discomfort to the patient, while preserving the salivary gland.

by ultrasonography accounted for the absence of untoward reactions of complications in all patients. The main physical features of the piezoelectric lithotripter that we used include a small focal zone (17 x 4 x5 mm, less

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1. Rauch



G, Miehlke A, Haubrich J, Chilla R. Diseases of the salivaryglands. Stuttgart: Thieme, 1986: 91-97. 3. Epker BN. Obstructive and inflammatory diseases of the major salivary glands. J Oral Surg 1972; 33: 2-27. 4. Coleman AJ, Saunders JE. A survey of the acoustic output of commercial extracorporeal shock wave lithotripters. Ultrasound Med Biol 1989; 15: 2. Seifert


H, Nitsche N, Meier J, Wirtz PM, Ell C. Piezoelectric shockwave lithotripsy of salivary gland stones: an in vitro feasibility study. J Lith

5. Iro

Stone Dis 1991; 3: 211-16. 6. Iro H, Wessel B, Benzel W, et al. Gewebereaktionen unter Applikation von piezoelektrischen Stoßwellen zur Lithotripsie von Speichelsteinen. Laryngo-Rhino-Otol 1990; 69: 102-07.

H, Nitsche N, Schneider Th, Ell C. Extracorporeal shockwave lithotripsy of salivary gland stones. Lancet 1989: ii: 115. 8. Seldin HW, Seldin SD, Rakower W. Conservative surgery for the removal of salivary calculi. J Oral Surg 1953; 6: 579-87. 9. Patey DH, Moffat W. A clinical and experimental study of functional paralysis of the facial nerve following conservative parotidectomy. Br J Surg 1961; 48: 435-40. 10. Kenefick JS. Some aspects of salivary gland disorders. Br J Surg 1961; 48: 7. Iro

435-40. 11. Seward GR. Anatomic surgery of salivary calculi. VII: complications of salivary calculi. Oral Surg 1968; 26: 137-44. 12. Patey DH. Excision of submandibular gland. In: Rob C, Smith R, Wilson JSP, eds. Operative surgery: head and neck, 3rd ed, London: Butterworth-Heinemann, 1981: 835-38.

Value of the alert and action lines

based on a World Health model has been used for many years in Organisation the peripheral maternity clinics of Pikine, Senegal, to monitor labour. We have assessed the value of the partogram and efficacy of the alert and action lines. 1022 pregnant women were monitored by partogram during 4 months. The alert line was crossed in 100 (9·8%) of these cases and the frequency of neonatal resuscitation was higher for this group (relative risk 4·0, 95% confidence interval 2·3-7·1; p

Shockwave lithotripsy of salivary duct stones.

Surgical extirpation of the affected gland has been necessary for cases of sialolithiasis in which the stone cannot be removed by dilatation or dissec...
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