Scrotal pain.

Scrotal pain is a common and worrying symptom for which an adequate explanation cannot always be found. In this issue of the Postgraduate Medical Journal Dr Watanakunakorn' adds to the long list of possible causes of this form of pain. The nerve supply of the scrotum and its contents is derived from disparate parts of the nervous system. Within the scrotum, the testis, vas and epididymis appear to be innervated by sympathetic fibres from TI-T12 and TI-LI respectively, whilst the outer surface of the testis, the tunica vaginalis and the anterior scrotal skin receive somatic fibres from L1L2. The rest ofthe scrotal skin is innervated by somatic branches of S2-S3. Pain felt in the scrotum may therefore be referred from visceral or somatic structures with the same segmental nerve supply. Thus a stone impacted in the lower ureter, with a splanchnic LI innervation, may cause scrotal pain in this way, as may compression of the genitofemoral nerve by a small inguinal hernia, or, exceptionally, an aneurysm of the internal iliac artery. Degenerative lesions of the spine and, rarely, inflammatory or neoplastic disease of genital viscera may cause a similar referred pain. Pain which is generated by some change within the scrotum itself usually stimulates somatic as well as autonomic fibres and is therefore accurately localized to the scrotum. Cystic swellings of the scrotum rarely cause pain, although a very large hydrocele may cause discomfort by dragging on the cord or by distension of the tunica vaginalis. Should bleeding occur in a hydrocele or in an epididymal cyst or should they become infected, commonly after needle aspiration, then both may become acutely painful. Varicoceles are usually painless swellings, but exceptionally large ones can ache after exercise or after long periods of standing. Patients occasionally present with acute pain as a result ofthrombosis within the varicocity. Such pain is often encountered after high ligation or embolization of a varicocele and patients who undergo such procedures should be warned of the possibility of such pain thereafter. Testicular torsion commonly presents with acute pain accompanied by swelling and redness of the scrotum in children or young adults. However, Chapman & Walton2 in their study based at the London Hospital, showed that 44% of patients with testicular torsion initially presented with recurrent briefepisodes of scrotal discomfort. Such 'warning' pains presumably were relieved by the spontaneous untwisting of the cord. It remains imperative that any person suspected of having a testicular torsion should have an emergency surgical exploration of the scrotum. At such an operation the pain and swelling is occasionally found due to a torsion of the appendix testis (pedunculated hydatid of Morgagni). Very occasionally the clinical diagnosis can be made before the operation if the child is seen early enough to allow the doctor to identify a tender swelling localized to the upper pole ofthe testis. More commonly the scrotum becomes swollen and painful too quickly to permit such discrimination. Spontaneous fat necrosis and ideopathic scrotal oedema are often listed as possible differential diagnoses of testicular torsion in children. These exceptionally rare disorders should only be diagnosed after surgical exploration has taken place. True orchitis may involve one or both testicles and is seen most commonly in this country in association with mumps. Although not likely to cause long term problems in childhood, such orchitis can cause testicular atrophy in the 15% of adults with mumps who develop testicular pain and swelling. Draining a secondary hydrocele and incising the tunica albuginea may relieve the pain in extreme cases. Infectious mononucleosis, dengue fever and infection with coxsackie B virus may all occasionally produce an orchitis, whilst rarely an arteritis (Buerger's disease, polyarteritis nodosa, Henoch-Sch6nlein purpura) may present in this way. In an adult the commonest cause of acute scrotal pain is epididymal infection. Before the antibiotic era gonorrhoea was regarded as the commonest cause of acute epididymitis, but now infecting organisms are not always easily identified. Mittemeyer et al.3 were