Journal of the Royal Society of Medicine Volume 72 February 1979
155
Table 1. EEG abnormalities found in 619 healthy, adult subjects (extracted from Gibbs & Gibbs 1964)
Age
Percentage Number abnormal
20-29
275
11.200
30-39 40-49 50-59 60 +
116 89 76 63
12.1°, 11.30. 10.40) 8.00,
Nature of abnormality 14- & 6-per-second positive spikes and/or 6-per-second positive spikes Small sharp spikes and/or mittens Small sharp spikes and/or mittens Small sharp spikes and/or mittens Small sharp spikes and minimal temporal slow waves
and 6-per-second positive spikes on the EEG. John (1976), using spectral analysis of the EEG and evoked responses, found that 49% of 144 healthy subjects were classified, using multivariate analysis, as abnormal. Each of these healthy subjects was judged to be normal by clinical standards and conventional EEG interpretation before being included in the data base. Dr Critchley says that: 'The prime explanation for the expansion of routine EEG work is surely the development of interest in all aspects of epilepsy...' The value of the EEG in the management of adult epileptics in London was studied by Hopkins & Scrambler (1977). Of the 77 (86X of their series) who had EEGs, they were able to trace at least one recording or report on 72 of them. They found that the EEGs of 15 were entirely normal and of another 23 virtually normal; a review of the patients' notes showed that none of the abnormal EEGs contributed to patient management. Hopkins & Scrambler continued by saying that 5 out of 12 subjects having more than one grand mal attack per month had repeatedly normal EEGs, and 4 out of 13 subjects having only an occasional seizure had highly abnormal EEGs. They concluded by stating: 'A biochemical test with so many false negatives would never have entered clinical practice'. Gibbs & Gibbs (1964), in their sample of more than 38 000 EEGs from subjects with neurological diagnoses, found a false-negative rate of 31%; while John (1976) states that published falsenegative rates for the EEG vary between 13% and
60%. Finally, Auerbach et al. (1977) have developed techniques for studying the EEG that are capable either of averaging noise or of improving the signal-to-noise ratio in the absence of any triggering or synchronizing pulse. They have shown that EEGs of the type ordinarily encountered in clinical work are apparently composed of only pseudorandom noise, and state that 'The results are further support of the claim that no signal waveform with features distinct from those of random noise is present in the EEG'.
Clearly these extracts from the literature are only part of the total picture of the value of the EEG. If, however, it is still the case that 'the greater part of the work of most EEG departments consists of doing single records in patients referred by clinicians almost wholly ignorant of the value and limitation of the technique' (Matthews 1973), clinicians must have their attention drawn to the limitations of the EEG as well as to its advantages. Yours sincerely P J BOURDILLON
10 November 1978
References Auerbach V H, Baird H W & Grover W (1977) IEEE Transactionis on Biomedical Engineering 24, 399-402 Gibbs F A & Gibbs E L (1964) Atlas of Electro-encephalography, vol III. AddisonWesley, Cambridge, Massachusetts Hopkins A & Scrambler G (1977) Lancet i, 183-186 John E R (1976) Triangle 15, 77-89 Long M T & Johnson L C (1968) Neurology 18, 714-716 Matthews W B (1973) Journal oJ the Rosal College of Physi(ians of Londlon 7, 207-212 O'Connor P (1964) ElectroencephalographY and Clinical Neurophysiology 17, 341
Misdiagnosis of testicular tumours From Mr T P N Jenkins Royal Surrey County Hospital, Guildford, Surrey Sir, Hill reports 37 missed diagnoses of neoplasms of testicle in a series of 100 cases, owing to confusion with epididymo-orchitis (October 1978 Journal, p 737). In 1971, having made a similar error, I commenced referring patients for softtissue radiography, using a mammogram machine. Some of my surgical and urological colleagues have brought testography into general use in Guildford. The results (Price & Loveday 1975, Loveday & Price 1978) show that radiological examination of testicles complements clinical examination and provides important additional
156
Journal of the Royal Society of Medicine Volume 72 February 1979
information. Neoplastic changes in the testicle can be recognized and differentiated, from benign conditions before the clinical diagnosis is clear. Price has developed a radiological technique in which the dose is negligible - only 0.2 rad per exposure. The examination is simple and the opposite testicle, if normal, acts as a control. Yours faithfully T P N JENKINS
13 November 1978
References Loveday B J & Price J L (1978) Clinical Radiology 29, 685-689 Price J L & Loveday B J (1975) British Journal of Radiology 48, 179-180
Re-examination of antenatal care From Dr L Wislicki Clinical Associate Professor of Pharmacology, Hebrew University-Hadassah Medical School, Jerusalem, Israel Sir, It may be a correct observation that 'most doctors are literate but few are numerate' (Chamberlain, September 1978 Journal, p 662), but since the thalidomide disaster physicians are very interested in data on the incidence of drug-induced congenital malformations, a subject not mentioned in Mr Chamberlain's paper. Both the public and doctors are eager to know which drugs may safely be used in pregnancy, especially during the first few months when morphogenic movements result in the formation of different tissues and organs, though the later period should not be neglected; thus the descent of the testes and the formation of primary ovarian follicles take place after approximately seven months (Nishimura & Tanimura 1975). Animal research on the effect of drugs on the fetus has been very extensive, but very often the doses used have exceeded the doses given in clinical practice. In any case, for various reasons, including differences in metabolism, the results obtained in other species cannot be decisive in establishing safety or danger in human pregnancy. Numerous retrospective papers have been published on the effects of different drugs on incidence and type of congenital malformations in man. Sometimes clinical observation has been successful, as for example when it was established in this way that maternal rubella during the early weeks of pregnancy is associated with heart disease, cataract and other defects in the infant (Gregg 1941). But in many cases the findings have been
equivocal. In a prospective study of over 50 000 pregnancies (Heinonen et al. 1977) the possible teratogenic effect of several hundred drugs was examined. Other factors such as smoking were also taken into consideration. In some cases, such as the
antimetabolites, the association with fetal defects was evident. Regarding other drugs, statisticallyevaluated results have been contradictory or indicate that they are teratogenic but that the findings require confirmation. For instance, the incidence of cleft lip, cleft palate or both after meclizine used during the first trimester of pregnancy against vomiting was, in 3.333 children, 2-3 times higher than expected (Lenz 1966). On the other hand, in a prospective study of 4277 pregnant women, 317 of whom took meclizine, rates of malformations, abortions and perinatal mortality compared favourably with the remainder of the group (Yerushalmi & Milkovich 1965). It may be assumed a priori that during the period of organogenesis the sensitivity of the developing fetus to external agents such as drugs will vary from time to time, perhaps from day to day. In the rat, for example, a dimethyltriazene has little action when injected on the 10th day of pregnancy but is highly teratogenic on day 14 (Berry & Poswillo 1975). Therefore, it seems most desirable, and perhaps for practical medicine imperative, to collect reliable data on timing as well as the dosage of drugs given in pregnancy. Systematic studies in humans may eventually furnish enough data to determine that under clinical conditions a drug is not associated with congenital malformations. In marginal cases other factors like smoking and exposure to chemicals will have to be taken into consideration. Yours sincerely L WISLICKI
-
6 November 1978
References Berry C L & Poswillo D E (1975) Teratology. Springer-Verlag, Berlin etc; p 49 Gregg N M (1941) Transactions of the Ophthalmological Society of Australia 3, 35 Heinonen 0 P, Slone D & Shapiro S (1977) Birth Defects and Drugs in Pregnancy. Publishing Sciences Group, Littleton, Massachusetts Lenz W
(1966) American Journal of Diseases of Children 112. 99 Nishimura H & Tanimura T (1975) Clinical Aspects of the Teratogenicity of Drugs. Excerpta Medica, Amsterdam & Oxford; pp 6-7 Yerushalmi J & Milkovich L (1965) American Journal of Obstetrics and Gynecology 93, 553
Malaria and the Maudsley Hospital (November 1978 Journal, pp 853-854) From Professor P M Daniel Royal College of Surgeons of England Dear Sir, When I went to the Maudsley Hospital, some 22 years ago, my old friend Dr E H J Schuster (well-known to and much admired by generations of MRC and Oxford physiologists for the DaleSchuster pump and scores of other ingenious
155
Table 1. EEG abnormalities found in 619 healthy, adult subjects (extracted from Gibbs & Gibbs 1964)
Age
Percentage Number abnormal
20-29
275
11.200
30-39 40-49 50-59 60 +
116 89 76 63
12.1°, 11.30. 10.40) 8.00,
Nature of abnormality 14- & 6-per-second positive spikes and/or 6-per-second positive spikes Small sharp spikes and/or mittens Small sharp spikes and/or mittens Small sharp spikes and/or mittens Small sharp spikes and minimal temporal slow waves
and 6-per-second positive spikes on the EEG. John (1976), using spectral analysis of the EEG and evoked responses, found that 49% of 144 healthy subjects were classified, using multivariate analysis, as abnormal. Each of these healthy subjects was judged to be normal by clinical standards and conventional EEG interpretation before being included in the data base. Dr Critchley says that: 'The prime explanation for the expansion of routine EEG work is surely the development of interest in all aspects of epilepsy...' The value of the EEG in the management of adult epileptics in London was studied by Hopkins & Scrambler (1977). Of the 77 (86X of their series) who had EEGs, they were able to trace at least one recording or report on 72 of them. They found that the EEGs of 15 were entirely normal and of another 23 virtually normal; a review of the patients' notes showed that none of the abnormal EEGs contributed to patient management. Hopkins & Scrambler continued by saying that 5 out of 12 subjects having more than one grand mal attack per month had repeatedly normal EEGs, and 4 out of 13 subjects having only an occasional seizure had highly abnormal EEGs. They concluded by stating: 'A biochemical test with so many false negatives would never have entered clinical practice'. Gibbs & Gibbs (1964), in their sample of more than 38 000 EEGs from subjects with neurological diagnoses, found a false-negative rate of 31%; while John (1976) states that published falsenegative rates for the EEG vary between 13% and
60%. Finally, Auerbach et al. (1977) have developed techniques for studying the EEG that are capable either of averaging noise or of improving the signal-to-noise ratio in the absence of any triggering or synchronizing pulse. They have shown that EEGs of the type ordinarily encountered in clinical work are apparently composed of only pseudorandom noise, and state that 'The results are further support of the claim that no signal waveform with features distinct from those of random noise is present in the EEG'.
Clearly these extracts from the literature are only part of the total picture of the value of the EEG. If, however, it is still the case that 'the greater part of the work of most EEG departments consists of doing single records in patients referred by clinicians almost wholly ignorant of the value and limitation of the technique' (Matthews 1973), clinicians must have their attention drawn to the limitations of the EEG as well as to its advantages. Yours sincerely P J BOURDILLON
10 November 1978
References Auerbach V H, Baird H W & Grover W (1977) IEEE Transactionis on Biomedical Engineering 24, 399-402 Gibbs F A & Gibbs E L (1964) Atlas of Electro-encephalography, vol III. AddisonWesley, Cambridge, Massachusetts Hopkins A & Scrambler G (1977) Lancet i, 183-186 John E R (1976) Triangle 15, 77-89 Long M T & Johnson L C (1968) Neurology 18, 714-716 Matthews W B (1973) Journal oJ the Rosal College of Physi(ians of Londlon 7, 207-212 O'Connor P (1964) ElectroencephalographY and Clinical Neurophysiology 17, 341
Misdiagnosis of testicular tumours From Mr T P N Jenkins Royal Surrey County Hospital, Guildford, Surrey Sir, Hill reports 37 missed diagnoses of neoplasms of testicle in a series of 100 cases, owing to confusion with epididymo-orchitis (October 1978 Journal, p 737). In 1971, having made a similar error, I commenced referring patients for softtissue radiography, using a mammogram machine. Some of my surgical and urological colleagues have brought testography into general use in Guildford. The results (Price & Loveday 1975, Loveday & Price 1978) show that radiological examination of testicles complements clinical examination and provides important additional
156
Journal of the Royal Society of Medicine Volume 72 February 1979
information. Neoplastic changes in the testicle can be recognized and differentiated, from benign conditions before the clinical diagnosis is clear. Price has developed a radiological technique in which the dose is negligible - only 0.2 rad per exposure. The examination is simple and the opposite testicle, if normal, acts as a control. Yours faithfully T P N JENKINS
13 November 1978
References Loveday B J & Price J L (1978) Clinical Radiology 29, 685-689 Price J L & Loveday B J (1975) British Journal of Radiology 48, 179-180
Re-examination of antenatal care From Dr L Wislicki Clinical Associate Professor of Pharmacology, Hebrew University-Hadassah Medical School, Jerusalem, Israel Sir, It may be a correct observation that 'most doctors are literate but few are numerate' (Chamberlain, September 1978 Journal, p 662), but since the thalidomide disaster physicians are very interested in data on the incidence of drug-induced congenital malformations, a subject not mentioned in Mr Chamberlain's paper. Both the public and doctors are eager to know which drugs may safely be used in pregnancy, especially during the first few months when morphogenic movements result in the formation of different tissues and organs, though the later period should not be neglected; thus the descent of the testes and the formation of primary ovarian follicles take place after approximately seven months (Nishimura & Tanimura 1975). Animal research on the effect of drugs on the fetus has been very extensive, but very often the doses used have exceeded the doses given in clinical practice. In any case, for various reasons, including differences in metabolism, the results obtained in other species cannot be decisive in establishing safety or danger in human pregnancy. Numerous retrospective papers have been published on the effects of different drugs on incidence and type of congenital malformations in man. Sometimes clinical observation has been successful, as for example when it was established in this way that maternal rubella during the early weeks of pregnancy is associated with heart disease, cataract and other defects in the infant (Gregg 1941). But in many cases the findings have been
equivocal. In a prospective study of over 50 000 pregnancies (Heinonen et al. 1977) the possible teratogenic effect of several hundred drugs was examined. Other factors such as smoking were also taken into consideration. In some cases, such as the
antimetabolites, the association with fetal defects was evident. Regarding other drugs, statisticallyevaluated results have been contradictory or indicate that they are teratogenic but that the findings require confirmation. For instance, the incidence of cleft lip, cleft palate or both after meclizine used during the first trimester of pregnancy against vomiting was, in 3.333 children, 2-3 times higher than expected (Lenz 1966). On the other hand, in a prospective study of 4277 pregnant women, 317 of whom took meclizine, rates of malformations, abortions and perinatal mortality compared favourably with the remainder of the group (Yerushalmi & Milkovich 1965). It may be assumed a priori that during the period of organogenesis the sensitivity of the developing fetus to external agents such as drugs will vary from time to time, perhaps from day to day. In the rat, for example, a dimethyltriazene has little action when injected on the 10th day of pregnancy but is highly teratogenic on day 14 (Berry & Poswillo 1975). Therefore, it seems most desirable, and perhaps for practical medicine imperative, to collect reliable data on timing as well as the dosage of drugs given in pregnancy. Systematic studies in humans may eventually furnish enough data to determine that under clinical conditions a drug is not associated with congenital malformations. In marginal cases other factors like smoking and exposure to chemicals will have to be taken into consideration. Yours sincerely L WISLICKI
-
6 November 1978
References Berry C L & Poswillo D E (1975) Teratology. Springer-Verlag, Berlin etc; p 49 Gregg N M (1941) Transactions of the Ophthalmological Society of Australia 3, 35 Heinonen 0 P, Slone D & Shapiro S (1977) Birth Defects and Drugs in Pregnancy. Publishing Sciences Group, Littleton, Massachusetts Lenz W
(1966) American Journal of Diseases of Children 112. 99 Nishimura H & Tanimura T (1975) Clinical Aspects of the Teratogenicity of Drugs. Excerpta Medica, Amsterdam & Oxford; pp 6-7 Yerushalmi J & Milkovich L (1965) American Journal of Obstetrics and Gynecology 93, 553
Malaria and the Maudsley Hospital (November 1978 Journal, pp 853-854) From Professor P M Daniel Royal College of Surgeons of England Dear Sir, When I went to the Maudsley Hospital, some 22 years ago, my old friend Dr E H J Schuster (well-known to and much admired by generations of MRC and Oxford physiologists for the DaleSchuster pump and scores of other ingenious
