complications but inadequately comprehend the expected blood glucose profile." "Comprehend" is used to imply limited understanding, but this is.
complications but inadequately comprehend the expected blood glucose profile." "Comprehend" is used to imply limited understanding, but this is often a function of inadequate instruction. Any test is potentially harmful if the operator does not understand how to interpret or react to the data generated. This paper highlights that the keystone to good diabetic care is education. It in no way proves that blood glucose monitoring may itself be harmful by generating neurosis in patients with or without obsessional traits. M A BAXTER A D WRIGHT B M SINGH Department of Medicine, University of Birmingham, and General Hospital, Birmingham B4 6NH
1 Beer SF, Lawson C, Watkins PJ. Neurosis induced by home monitoring of blood glucose concentrations. Br Med J 1989;298:362. (11 February.)
SIR,-With regard to the paper by Dr S F Beer and colleagues' we have recently encountered a similar case. A 52 year old man whose insulin regimen had been changed began monitoring his blood glucose concentration every two hours and contacted occupational nursing staff up to three times a day. Detailed counselling so that he understood the variations in glucose concentration that were acceptable led to a speedy resolution of the problem. Although our case is similar, there is an alternative interpretation of the problem. We thought that our case indicated a failure of communication, and this was supported by the patient's response to information and reassurance. We wonder whether Beer and colleagues are fair to judge the reported cases as a "neurosis in patients with obsessional traits." No information is given about the adequacy of diabetic control achieved by these patients, which had been assessed by urine analysis on previous insulin regimens. It is typical for glycaemic control to seem good on urine analysis whereas concurrent monitoring of blood glucose concentration shows fluctuations.2 When monitoring techniques are changed patients who are aware of the importance of good metabolic control may be distressed to find that their diabetic control is not as stable or as "normal" as it previously seemed. Also no information is given why the patients were thought to have obsessional personalities. The finding that all three cases (like ours) had a gratifying response to re-education suggests that they had not been adequately prepared for the new form of monitoring and that they were in fact being educated for the first time. Attaching psychiatric labels to such patients without adequate reason or formal assessment is inappropriate and serves only to draw attention away from the doctor's responsibility to provide good education and counselling. STEVE BAIN TONY BARNETT East Birmingham Hospital, Birmingham B9 5ST I Beer SF, Lawson C, Watkins PJ. Neurosis induced by home monitoring of blood glucose concentrations. Br Med J 1989;
298:362. (11 February.) 2 Walford S, Gale EAM, Allison SP, Tattersall RB. Self monitoring of blood glucose. Lancet 1978;i:732-5.
Luxation of the globe SIR,-Dr R M Pope has drawn attention to a hazard of the use of the exophthalmometer in a patient with Graves' ophthalmopathy, who developed luxation of the globe after the instrument was placed at the lateral orbital margin. I have seen two patients, both with dysthyroid
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eye disease, who developed similar luxation of the globe without the use of an exophthalmometer. One patient had globe luxation during fundus examination with an indirect ophthalmoscope and a second during intraocular pressure measurement with a Goldman applanation tonometer. The second patient claimed that she had experienced several similar episodes spontaneously at home. Both patients required digital separation of the lids by the examiner, and the globes were repositioned easily by gentle pressure. Duke-Elder states that for this alarming, and occasionally spontaneous, phenomenon the orbits must be shallow and the supporting fascia of the lids and extraocular muscles must be lax.2 The three cases described would suggest that the extra factor of backward displacement of the orbital septum is important for the globe to herniate forwards. If the eye is repositioned quickly the event seldom leads to serious ocular problems, and in both cases described a lateral tarsorrhaphy prevented further recurrence.
Finally, Mr Baird bemoans the lack of data on carotid ultrasound studies in the recently reported United Kingdom transient ischaemic attacks trial of aspirin. The trial began in 1979, when the diagnostic value of carotid ultrasound was not widely accepted in the United Kingdom, and the equipment was certainly not readily available to the neurologists collaborating in the trial. Indeed, many United Kingdom neurologists still do not have easy access to this extremely useful non-invasive technique; it is a deficiency which should be rectified. PETER SANDERCOCK Department of Neurology, Western General Hospital, Edinburgh EH4 2XU I Baird RN. Aspirin for strokes and transient ischaemic attacks. BrMedJ 1989;298:321. (4 February.) 2 Sandercock P. Aspirin for strokes and transient ischaemic attacks. BrMedJf 1988;297:995-6. 3 Antiplatelet Trialists Collaboration. Secondary prevention of vascular disease by prolonged antiplatelet therapy. Br MedJ 1988;2%:320-31.
MICHAEL E NELSON University Department of Ophthalmology, Royal Hallamshire Hospital, Sheffield S10 2JF
***This correspondence is now closed. - ED, BMJ.
I Pope RM. Unusual complication of the use of a Hertel exophthalmometer in a patient with Graves' ophthalmopathy. Br Med J 1989;298:365. (II February.) 2 Duke-Elder S. Svstem of ophthalmologjy. Vol 13, part 2. London: Henry Kimpton, 1974;1233-4.
Long hours of work in junior doctors
Aspirin for strokes and transient ischaemic attacks SIR,-Mr R N Baird has unfortunately misconstrued my English,' perhaps because I did not express myself clearly enough. I was prompted to write my article2 because it seemed that in the United Kingdom very few patients with transient ischaemic attacks and stroke were being referred for assessment (and entry, where appropriate, in the European Carotid Surgery Trial, which is coordinated from here). Inquiry among local general practitioners soon showed that, because aspirin is so readily available, cheap, and non-toxic, "doctors may not feel it worth referring patients for carotid surgery."2 I phrased this to be a lament that patients were being denied a treatment of possible value, not a statement that endarterectomy is worthless. (If I believed that the operation was worthless, I wouldn't be participating in the European Carotid Surgery Study.) While I agree with Mr Baird that carotid endarterectomy may be of value, I disagree that there is a consensus that patients with severe stenosis must be treated surgically. If such a consensus did exist, why are so many surgeons in 66 centres collaborating in the European Carotid Surgery Trial and why are they prepared to enter patients (which entails random allocation of selected patients with different degrees of stenosis, some with severe disease, to either best medical treatment or best medical treatment plus surgery)? The latter is an important point; the relevant comparison is not, as Mr Baird suggests, aspirin versus surgery, but aspirin versus aspirin plus surgery. The data that he cites from the Toronto study by Chambers and Norris relate to patients with asymptomatic stenosis of the carotid artery; such data may not necessarily apply to symptomatic patients with transient ischaemic attacks or stroke and carotid stenosis. Furthermore, the two randomised trials of aspirin in patients with asymptomatic carotid stenosis are not yet complete, so the value of aspirin in such patients is still sub judice, although by extrapolation from trials in symptomatic patients' it is likely to be effective.
SIR, -We would like to reply to some of the points raised in correspondence about our paper.' The riposte that we simply confirmed the obvious2 overlooks the widespread lack of scientific confirmation for any decline in cognitive performance of junior doctors after night duty, evidence reported in our paper and claimed by Dr J N Cashman and others2 and by Ms Anne Spurgeon and Dr Jane Sims.' Though no investigator has failed to disclose adverse effects with subjective reports of mood, the commonplace failure to obtain objective evidence with laboratory tests, we think, is owing to the types of functions examined; the need to avoid tasks of short duration, in which it is only too easy for subjects to marshal their resources and compensate for fatigue; and the need to choose simple but telling tasks, which require sustained concentration and patience and in which the rate of information flow is monotonous or slow. It is well known from sleep deprivation studies that tiredness has minimal effects on tasks which are of high intrinsic interest, are perceived as testing one's mettle, and are intellectually challenging.4 Tiredness is more readily disclosed by simple, monotonous tasks, which tax powers of sustained concentration. Patient care includes both components. These conjectures were supported in our investigation: long hours of work had no effect on a video choice reaction time task, in which rate of information flow was high, but had sizable effects on tactual discriminations requiring careful concentration and on a vigilance task in which signals appeared infrequently. In casting doubt on what could be called the ecological significance of the results, Ms Spurgeon and Dr Sims have overlooked the five second decrement in haptic sorting times. This test provides a measure of central nervous system processing time and is sensitive to cognitive slowing with age (R Baxter, J Gruzelier, unpublished data) and hypnosis." Furthermore, tactual discriminations are important in both medicine and surgery. A final point worth emphasising because it was overlooked is that it was the long hours of work rather than loss of sleep that were responsible for the decline in performance; whether junior doctors had more or less than five hours' sleep showed a significant performance decrement only in one test-the choice reaction time task. This may explain why Cashman and others report null results,' because they examined junior doctors in
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the morning immediately after night duty, rather than later in the afternoon after 31 continuous hours on duty, as we did. This is surely where the moral lies when it comes to considering the implications of our study for clinical practice. It is the long hours of continuous work rather than sleep loss that is the main culprit. J H GRUZELIER D I ORTON
Department of Psychiatry, Charing Cross and Westminster Mledical School, London W6 8RF I Orton DI, Gruzelier JH. Adverse changes in mood and cognitive performance of house officers after night duty. Br Med J 1989;298:21-3. (7 January.) 2 Spurgeon A, Sims J. Lack of sleep in junior doctors. Br Medl 1989;298:381-2. (11 February.) 3 Cashman JN, Jones H, Skelly AM. Lack of sleep in junior doctors. BrMedJ 1989;298:381. (11 February.) 4 Horne JA. Restitution and human sleep: a critical review. Physiol Psychol 1979;7:115-25. 5 Gruzelier J, Brow T, Perry A, Rhonder J, Thomas M. Hypnotic susceptibility: a lateral predisposition and altered cerebral asymmetry under hypnosis. Intl Psychophysiol 1984;2:131-9. 6 Cikurel K, Gruzelier JH. The effect of an active-alert hypnotic induction on lateral asymmetry in haptic processing. BrJ Exp Clin Hypnosis (in press).
Aluminium accumulation and immunosuppression SIR,-Drs K P Nordal and colleagues and Dr A Davenport and others have recently drawn attention to a possible link between aluminium overload and immunosuppression in renal transplant recipients. ' 2 In fact, Silke et al had observed a low incidence of transplant rejection despite poor tissue antigen matching in seven patients with dialysis encephalopathy as early as 1978.' Observations on an extended series including these patients did not confirm the trend, with at least one frank clinical or histological rejection episode occurring in nine of 23 transplanted encephalopathic patients, and high dose steroids given to a further nine for suspected rejection.4 Fifteen patients, however, developed bacterial or cytomegalovirus infection, contributing to death in 13, and the dose of azathioprine required adjustment because of leucopenia in nine cases. Furthermore, four patients displayed low serum IgA concentrations.5 Of the last six patients in the series, five subsequently did well with good graft function at least 12 months after transplantation. Possible factors in the improved prognosis included an embargo on aluminium for at least six months before transplantation and careful attention to calcium balance in the postoperative period. Though these observations are consistent with an immunosuppressive effect of aluminium, further work needs to be done on cellular and humoral immunity in patients with aluminium overload. Transplantation is an effective treatment for patients with frank clinical aluminium intoxication, but the aluminium burden should be first reduced by an embargo and possibly desferrioxamine chelation treatment. PETER GARRETT Wessex Regional Renal Unit, St Mary's Hospital, Portsmouth, Hampshire P03 6AD 1 Nordal KP, Dahl E, Albrechtsen D, et al. Aluminium accumulation and immunosuppressive effect in recipients of kidney transplants. Br MedJ 1988;297:1581-9. (17 December.) 2 Davenport A, Toothill C, Davison AM, Newton KE, Will EJ, Giles GR. Aluminium accumulation and immunosuppression. BrMedJ7 1989;298:458-9. (18 February.) 3 Silke B, Fitzgerald GR, Hanson S, Carmody M, O'Dwyer WF. Dialysis dementia and renal transplantation. Dialysis and Transplantation 1978;7:486-7. 4 Garrett PJ. Aluminium poisoning. (MD thesis.) Liverpool: University of Liverpool, 1985. 5 Garrett PJ, Mulcahy D, Carmody M, O'Dwyer WF. Aluminium encephalopathy: clinical and immunological features. QJ7 Med 1988;69:775-83.
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Necrosis of skin induced by coumarin SIR,-The article by Dr Vito Grimaudo and colleagues on skin necrosis induced by coumarin' attracted our attention as coumarin itself could have been used to treat the necrotic lesions. Many patients with cancer are treated with the dicoumarin type oral anticoagulants warfarin and nicoumalone (Sinthrome),2 and any necrotic lesions that develop are treated by local application of coumarin. Coumarin is also used to prevent skin necrosis in herpes zoster and herpes simplex. "Sister Majella's cold sore cream," which is 1% coumarin in Silcock's base, has been used for years in our hospitals. In Switzerland coumarin is used to treat and prevent oedema,3 and it is marketed there by Schaper and Brummer (Saltzgitter, Federal Republic of Germany) under the name of Venalot. Dicoumarin type oral anticoagulants are often referred to as coumarin, but coumarin (1,2benzopyrone) has no anticoagulant action. It is a macrophage stimulant,4 enhancing proteolytic activity, and it is used in treating melanoma' and renal cell carcinoma.6 Coumarin is also being investigated in treating intracellular infections such as brucellosis, tuberculosis, and leprosy because of its macrophage stimulating effect. Recently, at the Ganta Leprosy Center in Liberia 24 patients with leprosy who had a total of 32 indolent necrotic ulcers resulting from burns were treated successfully with 1% coumarin in Silcock's base. It not only promoted healing but also reduced the smell and the flies, and these patients no longer need to be isolated. Both the patients and the staff were impressed and grateful. M CHAMBERS R D THORNES M MCKERNAN
Medical Missionaries of Mary, International Missionary Training Hospital, Drogheda, Republic of Ireland 1 Grimaudo V, Gueissaz F, Hauert J, Sarraj A, Kruithol J, Bachmann F. Necrosis of skin induced by coumarin in a patient deficient in protein S. Br Medj 1989;298:233-4. (28
January.) 2 Hilgard P, Thornes RD. Anticoagulants in the treatment of cancer. Eurj Cancer 1976;12:755-61. 3 Clodius L, Piller NB. Conservative therapy for post-mastectomy lymphoedema. Chirurgica Plastica 1978;4:193-6. 4 Pillar NR. The ineffectiveness of coumarin treatment on thermal oedema of macrophage free rats. Br j Exp Pathol 1976;57: 170-5. 5 Thornes RD, Lynch G, Sheehan MV. Cimetidine and coumarin therapy of melanoma. Lancet 1982;ii:328. 6 Marshall ME, Mendelsohn L, Butler K, et al. Treatment of metastatic renal cell carcinoma with coumarin (1,2 benzopyrone) and cimetidine: a pilot study. J Clin Oncol 1987;5: 862-6. 7 Thornes RD. Acquired immune suppression in chronic brucellosis. Irish Medj 1983;26:225.
Spina bifida occulta and functional disorders of the lower urinary tract SIR,-We compliment Mr A Fidas and colleagues on their excellent paper,' which at last provides hard numerical data to support our own clinical conviction that spina bifida occulta is a common anomaly found in urological patients and which should therefore be reported by radiologists. The authors have, however, overlooked our presentation at the June 1987 meeting of the British Association of Urological Surgery, where we reviewed published reports on spina bifida occulta in relation to enuresis and drew attention to their inadequacies. In patients referred for intravenous urograms from a urological clinic we found that 14-3% showed spina bifida occulta on the precontrast film compared with 7-4% of controls
having plain abdominal radiographs (p
