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COMPUTER-ASSISTED TOMOGRAPHYOF THE BRAIN

SiR,—" In these circumstances it is doubtful whether

neuroradiologists, neurologists, and neurosurgeons, becauseof their specialised viewpoint, are necessarily the rightpeople to advise on the strategic deployment of the EMIscanner in the community as a whole." We have examinedcarefully this astonishing conclusion to one of the longestleaders (Nov. 2, p. 1052) in The Lancet of recent times.You confirm that the EMI scanner is the most efficient

neuroradiological tool yet devised; with the enormousbonus to the patient, and to his doctor, that it is painlessand safe and totally free of the hazards of such invasiveprocedures as angiography, lumbar and ventricular airstudies, and myelography. For the physician, the bonusis his freedom to request the investigation, repeatedly ifneeds be, without fear of aggravating the patient’s illnessor of undermining his confidence. For the patient, thebonus is an investigation limited, at least in the case ofsuspected cortical atrophy, to the mild discomfort of EMIscanning, instead of the severe headache and prostration ofair studies.

After pleading for a prospective study of the efficiencyof the EMI scanner alongside other investigative methods,a proposal with which we fully agree, you define threemajor areas for its use: first, in the precise diagnosis andin the postoperative management of intracranial disorders;secondly, as a screening procedure for unsuspected diseasein patients with common syndromes; and, thirdly, as aresearch tool.The first and third of these roles clearly require the

machine to be in a combined neurosurgical-neurologicalcentre. Although we agree that the machine has a likelyuse in the survey of large groups of cases which would notnormally be referred to such a combined unit, we aresceptical of the value of technical as opposed to clinicalscreening of such populations. We think that such anextension to EMI scanning should be subjected to a

critical study.Whether or not the EMI scanner proves to be helpful

in the initial assessment of strokes and dementia, so

expensive a machine cannot be installed in every districtgeneral and psychiatric hospital. On the contrary, no siteseems more logical and economical than that very sub-regional centre of neurology and neurosurgery to whichsuch cases would automatically be referred if the scan werepositive. To us the real problems are not the place ofinvestigation but the ways and means of transportingpatients to the machine without their suffering hardship.It is in this aspect of transport that we agree with yourconclusions: here is a golden opportunity for the com-munity physician to show his mettle.

Division of Neurosciences,South Glamorgan A.H.A.(T.)University Hospital of Wales,Heath Park, Cardiff CF4 4XW.

A. S. BLIGHA. K. FRAZER

J. G. GRAHAMR. J. THOMPSONR. D. WEEKSC. E. C. WELLS.

MINOCYCLINE: POSSIBLE VESTIBULARSIDE-EFFECTS

SIR,-We have used minocycline for the treatment ofnon-specific genital infection. At St. Thomas’ Hospital,120 men were treated with minocycline, 100 mg. twicedaily for three weeks. Vestibular side-effects of the typedescribed by Dr Williams and others (Sept. 28, p. 744)occurred in 4 men (3%), all within the first week of treat-ment. At University College Hospital, 105 women weretreated with the same dose of minocycline; 15 (14%)

developed side-effects, again within the first week of

therapy.This difference between men and women in the incidence

of vestibular side-effects is too great to be accountedfor by differences in body-weight. It seems that theseside-effects, like those of some other drugs, are commonerin women than in men.

Department of Venereal Diseases,St. Thomas’ Hospital,London SE1, andDepartment of

Genitourinary Medicine,University College Hospital,

London WC1.

C. S. NICOLJ. D. ORIEL.

ANTIGENICITY OF MONOCOMPONENTINSULINS

SiR,—Dr Yue and Dr Turtle (Oct. 26, p. 1022) reportedthat three out of seven newly diagnosed diabetics developedinsulin antibodies. Change from previous form of insulinto monocomponent (M.C.) insulin did not reduce either theinsulin antibody level or the insulin requirement. The M.c.insulin preparations were found to contain 6% high-molecular-weight contaminant and 12% monodesamido-insulin. All insulins were maintained throughout at 4°C.It was concluded that the antigenicity of M.C. insulin maybe the result of inadequate removal of high-molecular-weight contaminants during purification.The clinical data indicate a higher degree of immuno-

genicity than could be expected from already publishedobservations on M.c. insulin,I-11 but they are not sufficientfor conclusions of statistical significance in this respect.The analytical data, however, reveal a gross inconsistencywith the specifications for M.C. insulin and indicate thatthe preparations have been exposed to a temperature of45 °C (113°F) for one month (rough estimate). Thisexposure would not cause a noticeable loss of potency.Under proper conditions of storage (including transport)M.C. insulin does not undergo any untoward changes(0-2 % polymerisation per year at 4°C). The M.c. insulinsdespatched for limited investigations in Australia had to bespecially cleared by authorities and may not have beenhandled according to the routine established for con-

ventional insulin. We regret to state that at this moment wecannot exclude the possibility of the M.c. insulin forinvestigation having been accidentally exposed to heaten route to the patient, and this is in fact most probable.

In the preparation of M.c. insulin, removal of high-molecular-weight contaminants is radical. Whereas Novo’sconventional 5-times crystallised insulin contained approxi-mately 2% proinsulin-like substances, the figures for M.C.insulin sent to Australia in the course of the past years are

1. Andreani, D. Proceedings of Francqui Foundation Colloquium,Brussels, 1973. Excerpta med. int. Congr. ser. no. 316, p. 68.

2. Andreani, D., Iavicoli, M., Colletti, A., Menzinger, G. Folia endocr.1972, 25, 516.

3. Bruni, B., D’Alberto, M., Osenda, M., Ricci, C., Turco, G. L.Diabetologia, 1973, 9, 492.

4. Bruni, B., Castellazzi, R., Osenda, M., Turco, G. L. Panminervamed. 1973, 15, 231.

5. Fankhauser, S., Michl, J. 3rd International Donau Symposium onDiabetes Mellitus, 1973.

6. Korp, W., Levett, R. E. Wien. klin. Wschr. 1973, 85, 326.7. Levett, R. E., Korp, W. 3rd International Donau Symposium on

Diabetes Mellitus, 1973.8. Mirouze, J., Orsetti, A., Schmouker, Y., Cartry, E., Almes, N.

Nouv. Pr. méd. 1973, 2, 1981.9. Schlichtkrull, J., Brange, J., Christiansen, Aa. H., Hallund, O.,

Heding, L. G., Jørgensen, K. H., Munkgaard Rasmussen, S.,Sørensen, E., Vølund, A. Horm. Metab. Res. 1974, 5, suppl. p. 134.

10. Teuscher, A. Diabetologia, 1974, 10, 211.11. Czyzyk, A., Lawecki, J., Rogala, H., Miedzinska, E., Popik-

Hankiewicz, A. ibid. p. 233.12. Schlichtkrull, J., Pingel, M., Heding, L. G., Brange, J., Jørgensen,

K. H. Handbook of Experimental Pharmacology (edited by A.Hasselblatt) (in the press); vol. XXXII/2; chap. II. Heidelberg.