DiscussionThis technique is simple to use, and most of the equipment is commercially available. It is acceptable to patients and enables impotence to be investigated in an ordinary, quiet hospital ward simply by admitting the patient for one or two nights. Direct measurements of penile erections correlate poorly with the presence of decreased libido or loss of morning erections7 and also with measurements of other aspects of peripheral or autonomic function. We believe that the technique represents a useful advance in the investigation of impotence, and we now use it routinely.Two-thirds of our diabetic patients had nocturnal erections with an increase in penile circumference and a duration that were within the range shown by the healthy subjects. We cannot imagine an organic lesion that would lead to failure of erection during sexual activity and yet permit normal nocturnal erections, so probably in these patients the impotence was mainly caused by psychological factors. Six diabetics and one healthy subject showed a maximum increase in penile circumference of under 15 mm. The healthy subject, who claimed not to be impotent, was studied only once and on repeated tests might have shown more nocturnal activity, but the diabetics were each studied at least twice. Five of the diabetics complained of total impotence, and all had postural hypotension due to autonomic neuropathy; two also had Charcot's joints. Impotence in these patients may therefore have had an organic basis.We suggest that in most diabetic patients who complain of impotence the problem is psychological rather than organic, but why impotence should apparently be so common among diabetics is not clear.' 2 Possibly a period of ill health or poor diabetic control causes transient autonomic neuropathy producing reversible organic impotence that might be continued owing to psychological complications. We find that patients are reassured by knowing their impotence does not indicate organic disease, and after this reassurance, or after psychotherapy, some of our patients have reported improved sexual performance. 14 Bennet, T, and Evans, D F, Journal of Physiology, 1976, 263, 105. 15 Bennet, T, et al, Diabetes, 1978, 27, 1167. (Accepted 9 September 1979 Praziquantel: a new schistosomicide against Schistosoma haematobium J E McMAHON, N KOLSTRUP British Medical journal, 1979, 2, 1396-1399 Summary and conclusions The effectiveness of the new schistosomicide praziquantel was assessed in African schoolchildren infected with Schistosoma haematobium. They were stratified according to the severity of their infection and were then randomly allocated to treatment with two single-dose regimens (30 and 40 mg/kg) and a split regimen of two doses of 20 mg/kg given four hours apart. All three regimens were highly effective and produced few side effects. Children who initially had very high pretreatment egg loads showed a poorer therapeutic response at all dose levels, and further investigations are necessary to find the optimum dose. Because of its effectiveness i...
