499
priate investigations performed, and any infection surgically eradicated. Although the organisms encountered in dental sepsis are usually sensitive to penicillin, this may not always be the case. Penicillinase-producing strains of Bacteroides melaninogenicus and B.oralis are resistant to penicillin.12 Destruction of penicillin in the abscess cavity by resistant organisims could reduce the efficacy of the agent against accompanying penicillin-sensitive bacteria. This effect has been demonstrated experimentally in mice infected with the penicillin-sensitive species Fusobacterium necrophorum, singly and in combination with penicillinase-producing strains of B.melaninogenicus or B.oralis.13-the latter two microorganisms 7
often present in dental infections.6 Initial chemotherapy of such frontal-lobe abscesses should consist of a combination of antimicrobial agents with a broad spectrum of activity, such as penicillin, metronidazole, and gentamicin. The regimen should be continued until the primary source of infection has been identified and the sensitivity of the causative bacteria determined. This can usually be accomplished in a matter of days by a technique which combines a selective culture medium with direct sensitivity testing.2 Clearly before frontal-lobe abscesses can be specifically linked with covert dental sepsis further detailed bacteriological studies of the flora of such abscesses must are
Preliminary
Communication
MYOGLOBINÆMIA IN DUCHENNE MUSCULAR DYSTROPHY PATIENTS AND CARRIERS: A NEW ADJUNCT TO CARRIER DETECTION BRUCE T. ADORNATO LAWRENCE W. KING ENGEL
J.
be carried out. We found that failure to observe gramnegative bacteria on microscopy in no way implies their absence. This underlines the necessity for sensitive and reliable techniques for the culture of obligate anaerobes and other fastidious microorganisms. We are grateful to Mr P. Bradnum, F.D.S.R.C.S., tor his assistance during the preparation of this paper. Requests for reprints should be addressed to H.R.I., Department of Microbiology, General Hospital, Newcastle upon Tyne NE4 6BE.
REFERENCES
Hollin, S. A., Hiroshi Hayashi, Gross, S. W. Oral Surg. Oral Med. Oral Path. 1967,23, 277. 2. Ingham, H. R., Dutton, J., Sisson, P. R., Sprott, M. S., Selkon, J. B. J. clin. Path. (in the press). 3. Cowan, S. T., Steel, K. J. in Manual for the Identification of Medical Bacteria (edited by S. T. Cowan); London, 1974. 4. Duerden, B. I., Holbrook, W. P., Collee, J. G., Watt, B. J. J. appl. Bact. 1976, 40, 163. 5. Tharagonnet, D., Sisson, P. R., Roxby, C. M., Ingham, H. R., Selkon, J. B. J. clin. Path. 1977, 30, 505. 6. Sabiston, C. B., Grigsby, W. R., Segerstrom, M. T. Oral Surg. 1976, 41, 1.
430. 7.
Ingham, H. R., Hood, F. J. C., Bradnum, P., Tharagonnet, D., Selkon, J. B. Br. J. oral Surg. 1977, 14, 264. 8. DeLouvois, J., Gortvai, P., Hurley, R. Br. med. J. 1977, ii, 981. 9. Heineman, H. S., Braude, A. I. Am. J. Med. 1963, 35, 682. 10. Sisher, H., Lloyd Du Brul, E. in Oral Anatomy (edited by H. Sisher and E. Lloyd Du Brul); p. 355. St. Louis, 1975. 11. Boyd, G. I.J. Anat. 1930, 65, 108. 12. Pinkus, G., Veto, G., Braude, A. I. J. Bact. 1968, 96, 1437. 13. Hackman, A. S., Wilkins, T. D. Archs oral Biol. 1976, 21, 385.
fetuses by placental aspiration and determination of fetal C.P.K. activity,6 if confirmed as reliable, would greatly increase the need for more sensitive and accurate carrier detection. We have used a sensitive complement-fixation assay to assess serum-myoglobin (M.G.B.) measurement in the detection of D.M.D. carriers. METHODS
KAGEN
Medical Neurology Branch, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, Maryland 20014, and Department 7 Medicine, Cornell University Medical Center, New York, U.S.A.
Myoglobinæmia was detected in 14 of 18 patients with Duchenne muscular dystrophy (D.M.D.) with a sensitive specific complement-fixation assay. Myoglobinæmia was also detected in 10 of 16 known D.M.D. carriers, including 4 with normal serum-creatine-phosphokinase activity. 9 of 27 possible carriers also had myoglobinæmia. It is suggested that this assay is a useful adjunct to present methods of carrier
Summary
detection in D.M.D. INTRODUCTION
DUCHENNE muscular dystrophy (D.M.D.) is a progressive and severely disabling disorder of unknown biochemical pathogenesis inherited in an X-linked recessive pattern. It is the most common of the so-called muscular dystrophies, with an incidence of 15-30 per 100 000 live births.1 Carriers detected by determination of serumcreatine-phosphokinase (C.P.K.) activity can be offered elective abortion of male fetuses identified by karyotyping of fetal fibroblasts obtained by amniocentesis. Unfortunately this method has a false-negative rate of 20—40%.2-5Antenatal diagnosis of affected Duchenne
Families considered for study contained at least 1 boy with Duchenne muscular dystrophy as diagnosed by history, physical examination, serum-C.P.K. activity, muscle-biopsy histochemistry, and electromyography. In 22 families we studied 18 D.M.D. patients (4 patients were not available for M.G.B. determination, but diagnosis had been previously established) and 43 female relatives. A woman was classified as a carrier if she had any one of the following: (i) a D.M.D. child and a D.M.D. male relative; (ii) 2 affected offspring (2 boys with D.M.D. or a D.M.D. boy and carrier daughter); or (iii) a son or other male relative with D.M.D. and elevated C.P.K. activity from no other apparent cause. Female relatives not fulfilling one of these criteria were considered possible carriers. 27 normal healthy women aged 19-59 yr (mean 32-6) volunteered for serum-M.G.B. determinations. Subjects were asked to confirm that they had had no unusual exertion in the week before the study: there were no other restrictions on physical activity. A forearm ischaemic exercise test (FIET) was done in all females in the D.M.D. families and in 16 normal female controls: blood-samples were drawn from the antecubital fossa for total C.P.K. activity, M.G.B., and lactate before and after 2 min of forced repeated grip exercise with a proximal blood-pressure cuff inflated above systolic pressure. C.P.K. activity was determined with a standard automated Technicon system (normal less than 150 units). Serum-M.G.B. was assayed with a complement-fixation technique.’ This immunological method is specific and has no reaction with haemoglobin, albumin, gamma-globulin, or other components of human serum or urine. It detects as little as 0-15 µg/ml. Sera from normal subjects is unreactive in this assay except after severe
physical stress.
500 RESULTS
patients.-14 of the 18 boys had detectable levels ranging from 0.2 to 3.0 µg/ml (mean 0.79 µg/ml). The 4 D.M.D. patients with negative M.G.B. assays did not differ notably from the 14 M.G.B.-positive boys with respect to age, clinical severity, or c.P.x. activity. Carriers.-There were 16 D.M.D. carriers, aged 9-59 (mean 32), 11 of whom were mothers of D.M.D. boys. 3 D.M.D.
serum-M.G.B.
of the 11 mothers and 1 other carrier had normal C.P.K. on at least three determinations. 9 of the 16 carriers had demonstrable myoglobinaemia on a pre-FIET sample, including all 4 women with normal c.P.K. levels (mean 0.75µg/ml). (see accompanying figure). Another carrier had a negative pre-exercise myoglobin value and a positive value immediately after the FIET (0-2 µg/ml). 1 other carrier (a D.M.D. mother) had a very high M.G.B. level (200 µg/mtl) on a random sample. However, a negative M.G.B. result was found on a repeat sample several months later. This woman was excluded from the study. Possible carriers.-The 27 possible carriers, aged 13-54 (mean 34), all had normal serum-c.P.K. levels. Myoglobinæmia was present in both before and after FIET (mean 0-44 µg/ml), and another 4 had myoglobinæmia only after FIET (mean 0.25 µg/ml) (see figure). Controls.-None of the 22 normal control women had myoglobinsemia either before or after FIET. There was no significant difference in post-FIET bloodlactate levels between M.G.B.-positive and M.G.13.-negative subjects. DISCUSSION
Though not previously reported in patients and carriers, the finding of myoglobinaemia in D.M.D. is not sur-
prising. The small size daltons), its abundance
of the M.G.B. molecule (17 500 in skeletal muscle, and the presumed "leakiness" of the D.M.D. muscle plasmalemma (as reflected by elevated. serum-c.P.K. activity) would probably allow abundant loss of M.G.B. into serum. The previous failure to detect myoglobinaemia8in D.M.D. may be attributed to lack of an assay sensitive enough to detect the low levels of M.G.B. persisting in serum in the presence of rapid renal glomerular filtration of M.G.B. Although the absolute values we detected were low (02-30 µg/ml), they were in the range found in acute myocardial infarctionand were readily detected by our assay system. The failure to detect myoglobinxmia in 4 of the 18 D.M.D. patients can probably be explained by measurement in single samples, for we have found a 10-fold fluctuation in serum-M.G.B. levels measured repeatedly over 36 h in a D.M.D. patient confined to bed.9 This intermittent elevation of M.G.B. in serum may be analogous to the "staccato phenomenon" seen in myocardial infarction10 and perhaps is due to intermittent release from muscle tissue. C.P.K. activity in this D.M.D. patient did not correlate with M.G.B. levels, since it remained essentially unchanged during this period. This may reflect the dissociation between measures of these two proteins seen in some D.M.D. carriers and possible carriers. We have also observed this variation of serum-M.G.B. in myasthenia gravis." (Striking variations in C.P.K. activity occur in ambulatory D.M.D. patients over periods of several weeks. 12 13) The observation of myoglobinasmia in 10 of 16 carriers, including 4 with normal C.P.K. activity, differs from the findings of a study of M.G.B. release in presumably normal subjects undergoing extreme exertion during military training.14 In the military recruits, myoglobinsemia was in the region of 1 µg/ml only when serum-c.p.K. was very high. Our findings in the D.M.D. female relatives demonstrate that skeletal muscle can be abnormal and leaking detectable M.G.B even though serum-c.p.K. levels are normal. The conditions are not comparable, however, since D.M.D. carriers have muscle
abnormalities, as occasionally seen histologically. A particularly important finding in our-study was that M.G.B. was
detectable in the
serum
of 9 of 27 female
patients who, by conventional C.P.K. or screening genetic history, had no evidence of being a carrier. In this group, 5 of 27 showed myoglobinsemia
relatives of
myoglobin (M.G.B.) and creatine-phosphokinase activity (C.P.K.) in female relatives of patients with Duchenne muscular dystrophy. Circles indicate values which did not change after exercise. Squares indicate positive post-FiET values in women who had negative values Serum
before exercise.
D.M.D.
both before and after a FIET, and another 4 had demonstrable myoglobinæmia only after a FIET. 3 women aged over 35 who were mothers of D.M.D. patients had normal serum-c.P.K. values on repeated sampling in our laboratory but had histories of elevated C.P.K. 5-10 yr earlier. All 3 had myoglobinsemia on pre-FIET samples. A decline in serum-c.P.K.-activity over years has been observed in both D.M.D. patients and carriers.15 Our finding ofmyoglobinaemia in these 3 women (which further demonstrates absence of correlation between serum-c.P.K. elevation and myoglobin release from muscle) suggests that this test might be useful for corroborating their carrier status and predicting it in others. Our results provide cautious optimism for improvement in ascertainment of D.M.D. carriers. If we assume that all 19 female D.M.D. relatives found to have myoglobinxmia are true carriers, less than half of these would have been detected by their elevated C.P.K. activity-a figure similar to other estimates. 16 17 Before advocating
501
genetic counselling in D.M.D., however, we must express the reservation that, myoglobinaemia like C.P.x. activity, is a non-specific finding. It may be found in myocardial injuryl0 and inflammatory myopathies,18 as well as in myophosphorylase deficiency, phosphofructokinase deficiency, trauma, extreme exertion, and a number of other conditions with muscle-cell damage.19 Careful evaluation of the patient’s clinical status is necessary for correct interpretation of myoglobinasmia. Furthermore, although we found no instances of myoglobinxmia after FIET in 22 female controls, many more must be examined before the same importance can be ascribed to post-FIET myoglobinaemia (seen in 5 possible carriers) as to the distinct abnormality of resting myoglobinaemia observed in 14 female
the
measurement
D.M.D.
of myoglobin for
relatives.
The complement-fixation assay is not yet generally available, but recent advances in M.G.B immunochemis-
try20 make it likely that radial radioisotope assay systems will
immunodiffusion and become commercially available. If so, detection of serum-M.G.B. may become important in carrier detection and hence in the control of Duchenne muscular dystrophy.
Hypothesis MIGRAINE: A BLOOD DISORDER? EDDA HANINGTON Wellcome Trust, 1 Park Square West, London NW1, and Princess Margaret Migraine Clinic, 22 Charterhouse Square, London EC1
suggested that a primary abnormality of platelet function can account for the diverse clinical, biochemical, and pathological findings reported in migraine.
Summary
It is
INTRODUCTION
COMMON migraine is twice as common as classical migraine and is defined as recurrent headache affecting chiefly one side of the head and often associated with nausea and vomiting. In classical migraine these symptoms are preceded by premonitory signs, called an aura. These signs are usually visual and are followed by the onset of headache within about 15 minutes. Any hypothesis for migraine has to explain both the prodromal symptoms of classical migraine and the headache phase of the attack.
My hypothesis is that a platelet abnormality is the primary cause of migraine. This places migraine among the commonest disorders of the blood. The clinical, biochemical, and pathological findings in migraine can, I suggest, be related to this primary abnormality of platelet function. MIGRAINE AND MONOAMINES
Stress-the most common cause of migraine-includes anxiety, excitement, fatigue, anger, and exertion. In some patients changes in plasma-levels of cestradiol and progesterone are associated with migraine attacks, as are eating certain foods and fasting. The important clinical observation on the precipitating causes of migraine is that they are cumulative in effect and are linked with increased vasoactive-monoamine metabo-
Requests for reprints should be addressed to B.T.A., Medical Neurology Branch, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, Maryland 20014, U.S.A. REFERENCES 1. 2.
Gardner-Medwin, D. J. med. Genet. 1970, 7, 334. Hughes, R. C., Park, D. C., Parsons, M. E., O’Brien, M. D.
J. Neurol. Neurosurg. Psychiat. 1971, 34, 527. 3. McCormick, D., Allen, I. V. Ulster med.J. 1976, 45, 79. 4. Moser, H., Mumenthaler, M., Weismann, U. Schweiz. med. Wschr. 1971, 101, 537. 5. Rotthauwe, H. W., Kowalewski, S. Arch. Kinderheilk. 1973, 115, 333. 6. Mahoney, M. J., Haseltine, F. P., Hobbins, J. C., Banker, B. Q., Casky, T., Golbus, M. S. New Engl. J. Med. 1977, 297, 968. 7. Kagen, L., Scheidt, S., Roberts, L., Porter, A., Saul, H. Am. J. Med. 1975, 58, 177. 8. Rowland, L. P., Layzer, R. B., Kagen, L. J. Archs Neurol., Chicago, 1968, 18, 272. 9. Adornato, B. T., Kagen, L., Engel, W. K. Unpublished. 10. Kagen, L. J., Scheidt, S., Butt, A.Am.J. Med. 1977, 62, 86. 11. Adornato, B. T., Engel, W. K., Kagen, L. J. Unpublished. 12. Mendell, J. R., Engel, W. K., Derrer, E. C. Nature, 1972, 239, 522. 13. Thomson, W. H. S. Myopathien; p. 219. Stuttgart, 1965. 14. Olerud, J. E., Homer, L. D., Carroll, H. W. New Engl. J. Med. 1975, 293, 483. 15. 16. 17.
Moser, H., Vogt, J. Lancet, 1974, ii, 661. Thompson, M. W., Murphy, E. G., McAlpine, T. J. J. Pediat. 1967, 71, 82. Gardner-Medwin, D., Pennington, R. J., Walton, J. N. neurol. Sci. 1971, 13,
459. 18. Kagen, L. J.J.Am. med.Ass. 1977, 237, 1448. 19. Rowland, L. P., Penn, A. S. Med. Clins N. Am. 1972, 56, 1233. 20. Boesken, W. H., Boesken, S., Maimer, A. Res. exp. Med. 1977, 171,
71.
lism. There appears to be a threshold level of monoamines in the blood which varies from person to person, but when the trigger is powerful enough and the threshold is exceeded then an attack of migraine follows. The vasoactive monoamines implicated in migraine
noradrenaline, adrenaline, 5-hydroxytryptamine (5-H.T.), tyramine, and p-phenylethylamine, which are broken down, at least partly, by the monoamine-oxidase (M.A.o.) group of enzymes. Platelet-M.A.o. activity is reduced in migraine patients and falls significantly during attacks. 12Platelet-m.A.o. activity increases with age, which may contribute to the lessening of the severity and frequency of migraine attacks with increasing age. In women, platelet-M.A.o. activity reaches a peak around the time of ovulation, with a nadir 5 to 11 days later.33 This may be linked with the high frequency of migraine attacks in some women just before menstruation. Changes in 5-H.T. metabolism in migraine have been extensively studied since they were first reported by Sicuteri and his colleagues4 in 1961. Plasma-5-H.T. levels rise before the onset of headache and fall sharply during the headache phase. Excretion of 5-hydroxyindoleacetic acid, a product of 5-H.T. metabolism, increases during attacks. 5’Reserpine, which has been used experimentally to induce headache in migraine patients, causes 5-H.T. release and depletes the blood of its 5-H.T’. content by the breakdown of 5-H.T. All the 5-H.T. in blood is contained in platelets and is released when they
are
aggregate. ROLE OF INCREASED PLATELET AGGREGATION
Hilton and Cumings first reported an increase in platelet aggregation in migraine in 1971.6 Since then a great deal of work in this area has been published, culminating in a paper by Deshmukh and Meyerwhich showed that platelet behaviour is a major factor in the pathogenesis of migraine and that the chief precipitating causes of migraine are closely linked with factors causing platelet aggregation. For example, stress results in an increase in plasma adrenaline, noradrenaline, and arachidonic acid, all of which can cause platelet aggregation.
priate investigations performed, and any infection surgically eradicated. Although the organisms encountered in dental sepsis are usually sensitive to penicillin, this may not always be the case. Penicillinase-producing strains of Bacteroides melaninogenicus and B.oralis are resistant to penicillin.12 Destruction of penicillin in the abscess cavity by resistant organisims could reduce the efficacy of the agent against accompanying penicillin-sensitive bacteria. This effect has been demonstrated experimentally in mice infected with the penicillin-sensitive species Fusobacterium necrophorum, singly and in combination with penicillinase-producing strains of B.melaninogenicus or B.oralis.13-the latter two microorganisms 7
often present in dental infections.6 Initial chemotherapy of such frontal-lobe abscesses should consist of a combination of antimicrobial agents with a broad spectrum of activity, such as penicillin, metronidazole, and gentamicin. The regimen should be continued until the primary source of infection has been identified and the sensitivity of the causative bacteria determined. This can usually be accomplished in a matter of days by a technique which combines a selective culture medium with direct sensitivity testing.2 Clearly before frontal-lobe abscesses can be specifically linked with covert dental sepsis further detailed bacteriological studies of the flora of such abscesses must are
Preliminary
Communication
MYOGLOBINÆMIA IN DUCHENNE MUSCULAR DYSTROPHY PATIENTS AND CARRIERS: A NEW ADJUNCT TO CARRIER DETECTION BRUCE T. ADORNATO LAWRENCE W. KING ENGEL
J.
be carried out. We found that failure to observe gramnegative bacteria on microscopy in no way implies their absence. This underlines the necessity for sensitive and reliable techniques for the culture of obligate anaerobes and other fastidious microorganisms. We are grateful to Mr P. Bradnum, F.D.S.R.C.S., tor his assistance during the preparation of this paper. Requests for reprints should be addressed to H.R.I., Department of Microbiology, General Hospital, Newcastle upon Tyne NE4 6BE.
REFERENCES
Hollin, S. A., Hiroshi Hayashi, Gross, S. W. Oral Surg. Oral Med. Oral Path. 1967,23, 277. 2. Ingham, H. R., Dutton, J., Sisson, P. R., Sprott, M. S., Selkon, J. B. J. clin. Path. (in the press). 3. Cowan, S. T., Steel, K. J. in Manual for the Identification of Medical Bacteria (edited by S. T. Cowan); London, 1974. 4. Duerden, B. I., Holbrook, W. P., Collee, J. G., Watt, B. J. J. appl. Bact. 1976, 40, 163. 5. Tharagonnet, D., Sisson, P. R., Roxby, C. M., Ingham, H. R., Selkon, J. B. J. clin. Path. 1977, 30, 505. 6. Sabiston, C. B., Grigsby, W. R., Segerstrom, M. T. Oral Surg. 1976, 41, 1.
430. 7.
Ingham, H. R., Hood, F. J. C., Bradnum, P., Tharagonnet, D., Selkon, J. B. Br. J. oral Surg. 1977, 14, 264. 8. DeLouvois, J., Gortvai, P., Hurley, R. Br. med. J. 1977, ii, 981. 9. Heineman, H. S., Braude, A. I. Am. J. Med. 1963, 35, 682. 10. Sisher, H., Lloyd Du Brul, E. in Oral Anatomy (edited by H. Sisher and E. Lloyd Du Brul); p. 355. St. Louis, 1975. 11. Boyd, G. I.J. Anat. 1930, 65, 108. 12. Pinkus, G., Veto, G., Braude, A. I. J. Bact. 1968, 96, 1437. 13. Hackman, A. S., Wilkins, T. D. Archs oral Biol. 1976, 21, 385.
fetuses by placental aspiration and determination of fetal C.P.K. activity,6 if confirmed as reliable, would greatly increase the need for more sensitive and accurate carrier detection. We have used a sensitive complement-fixation assay to assess serum-myoglobin (M.G.B.) measurement in the detection of D.M.D. carriers. METHODS
KAGEN
Medical Neurology Branch, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, Maryland 20014, and Department 7 Medicine, Cornell University Medical Center, New York, U.S.A.
Myoglobinæmia was detected in 14 of 18 patients with Duchenne muscular dystrophy (D.M.D.) with a sensitive specific complement-fixation assay. Myoglobinæmia was also detected in 10 of 16 known D.M.D. carriers, including 4 with normal serum-creatine-phosphokinase activity. 9 of 27 possible carriers also had myoglobinæmia. It is suggested that this assay is a useful adjunct to present methods of carrier
Summary
detection in D.M.D. INTRODUCTION
DUCHENNE muscular dystrophy (D.M.D.) is a progressive and severely disabling disorder of unknown biochemical pathogenesis inherited in an X-linked recessive pattern. It is the most common of the so-called muscular dystrophies, with an incidence of 15-30 per 100 000 live births.1 Carriers detected by determination of serumcreatine-phosphokinase (C.P.K.) activity can be offered elective abortion of male fetuses identified by karyotyping of fetal fibroblasts obtained by amniocentesis. Unfortunately this method has a false-negative rate of 20—40%.2-5Antenatal diagnosis of affected Duchenne
Families considered for study contained at least 1 boy with Duchenne muscular dystrophy as diagnosed by history, physical examination, serum-C.P.K. activity, muscle-biopsy histochemistry, and electromyography. In 22 families we studied 18 D.M.D. patients (4 patients were not available for M.G.B. determination, but diagnosis had been previously established) and 43 female relatives. A woman was classified as a carrier if she had any one of the following: (i) a D.M.D. child and a D.M.D. male relative; (ii) 2 affected offspring (2 boys with D.M.D. or a D.M.D. boy and carrier daughter); or (iii) a son or other male relative with D.M.D. and elevated C.P.K. activity from no other apparent cause. Female relatives not fulfilling one of these criteria were considered possible carriers. 27 normal healthy women aged 19-59 yr (mean 32-6) volunteered for serum-M.G.B. determinations. Subjects were asked to confirm that they had had no unusual exertion in the week before the study: there were no other restrictions on physical activity. A forearm ischaemic exercise test (FIET) was done in all females in the D.M.D. families and in 16 normal female controls: blood-samples were drawn from the antecubital fossa for total C.P.K. activity, M.G.B., and lactate before and after 2 min of forced repeated grip exercise with a proximal blood-pressure cuff inflated above systolic pressure. C.P.K. activity was determined with a standard automated Technicon system (normal less than 150 units). Serum-M.G.B. was assayed with a complement-fixation technique.’ This immunological method is specific and has no reaction with haemoglobin, albumin, gamma-globulin, or other components of human serum or urine. It detects as little as 0-15 µg/ml. Sera from normal subjects is unreactive in this assay except after severe
physical stress.
500 RESULTS
patients.-14 of the 18 boys had detectable levels ranging from 0.2 to 3.0 µg/ml (mean 0.79 µg/ml). The 4 D.M.D. patients with negative M.G.B. assays did not differ notably from the 14 M.G.B.-positive boys with respect to age, clinical severity, or c.P.x. activity. Carriers.-There were 16 D.M.D. carriers, aged 9-59 (mean 32), 11 of whom were mothers of D.M.D. boys. 3 D.M.D.
serum-M.G.B.
of the 11 mothers and 1 other carrier had normal C.P.K. on at least three determinations. 9 of the 16 carriers had demonstrable myoglobinaemia on a pre-FIET sample, including all 4 women with normal c.P.K. levels (mean 0.75µg/ml). (see accompanying figure). Another carrier had a negative pre-exercise myoglobin value and a positive value immediately after the FIET (0-2 µg/ml). 1 other carrier (a D.M.D. mother) had a very high M.G.B. level (200 µg/mtl) on a random sample. However, a negative M.G.B. result was found on a repeat sample several months later. This woman was excluded from the study. Possible carriers.-The 27 possible carriers, aged 13-54 (mean 34), all had normal serum-c.P.K. levels. Myoglobinæmia was present in both before and after FIET (mean 0-44 µg/ml), and another 4 had myoglobinæmia only after FIET (mean 0.25 µg/ml) (see figure). Controls.-None of the 22 normal control women had myoglobinsemia either before or after FIET. There was no significant difference in post-FIET bloodlactate levels between M.G.B.-positive and M.G.13.-negative subjects. DISCUSSION
Though not previously reported in patients and carriers, the finding of myoglobinaemia in D.M.D. is not sur-
prising. The small size daltons), its abundance
of the M.G.B. molecule (17 500 in skeletal muscle, and the presumed "leakiness" of the D.M.D. muscle plasmalemma (as reflected by elevated. serum-c.P.K. activity) would probably allow abundant loss of M.G.B. into serum. The previous failure to detect myoglobinaemia8in D.M.D. may be attributed to lack of an assay sensitive enough to detect the low levels of M.G.B. persisting in serum in the presence of rapid renal glomerular filtration of M.G.B. Although the absolute values we detected were low (02-30 µg/ml), they were in the range found in acute myocardial infarctionand were readily detected by our assay system. The failure to detect myoglobinxmia in 4 of the 18 D.M.D. patients can probably be explained by measurement in single samples, for we have found a 10-fold fluctuation in serum-M.G.B. levels measured repeatedly over 36 h in a D.M.D. patient confined to bed.9 This intermittent elevation of M.G.B. in serum may be analogous to the "staccato phenomenon" seen in myocardial infarction10 and perhaps is due to intermittent release from muscle tissue. C.P.K. activity in this D.M.D. patient did not correlate with M.G.B. levels, since it remained essentially unchanged during this period. This may reflect the dissociation between measures of these two proteins seen in some D.M.D. carriers and possible carriers. We have also observed this variation of serum-M.G.B. in myasthenia gravis." (Striking variations in C.P.K. activity occur in ambulatory D.M.D. patients over periods of several weeks. 12 13) The observation of myoglobinasmia in 10 of 16 carriers, including 4 with normal C.P.K. activity, differs from the findings of a study of M.G.B. release in presumably normal subjects undergoing extreme exertion during military training.14 In the military recruits, myoglobinsemia was in the region of 1 µg/ml only when serum-c.p.K. was very high. Our findings in the D.M.D. female relatives demonstrate that skeletal muscle can be abnormal and leaking detectable M.G.B even though serum-c.p.K. levels are normal. The conditions are not comparable, however, since D.M.D. carriers have muscle
abnormalities, as occasionally seen histologically. A particularly important finding in our-study was that M.G.B. was
detectable in the
serum
of 9 of 27 female
patients who, by conventional C.P.K. or screening genetic history, had no evidence of being a carrier. In this group, 5 of 27 showed myoglobinsemia
relatives of
myoglobin (M.G.B.) and creatine-phosphokinase activity (C.P.K.) in female relatives of patients with Duchenne muscular dystrophy. Circles indicate values which did not change after exercise. Squares indicate positive post-FiET values in women who had negative values Serum
before exercise.
D.M.D.
both before and after a FIET, and another 4 had demonstrable myoglobinæmia only after a FIET. 3 women aged over 35 who were mothers of D.M.D. patients had normal serum-c.P.K. values on repeated sampling in our laboratory but had histories of elevated C.P.K. 5-10 yr earlier. All 3 had myoglobinsemia on pre-FIET samples. A decline in serum-c.P.K.-activity over years has been observed in both D.M.D. patients and carriers.15 Our finding ofmyoglobinaemia in these 3 women (which further demonstrates absence of correlation between serum-c.P.K. elevation and myoglobin release from muscle) suggests that this test might be useful for corroborating their carrier status and predicting it in others. Our results provide cautious optimism for improvement in ascertainment of D.M.D. carriers. If we assume that all 19 female D.M.D. relatives found to have myoglobinxmia are true carriers, less than half of these would have been detected by their elevated C.P.K. activity-a figure similar to other estimates. 16 17 Before advocating
501
genetic counselling in D.M.D., however, we must express the reservation that, myoglobinaemia like C.P.x. activity, is a non-specific finding. It may be found in myocardial injuryl0 and inflammatory myopathies,18 as well as in myophosphorylase deficiency, phosphofructokinase deficiency, trauma, extreme exertion, and a number of other conditions with muscle-cell damage.19 Careful evaluation of the patient’s clinical status is necessary for correct interpretation of myoglobinasmia. Furthermore, although we found no instances of myoglobinxmia after FIET in 22 female controls, many more must be examined before the same importance can be ascribed to post-FIET myoglobinaemia (seen in 5 possible carriers) as to the distinct abnormality of resting myoglobinaemia observed in 14 female
the
measurement
D.M.D.
of myoglobin for
relatives.
The complement-fixation assay is not yet generally available, but recent advances in M.G.B immunochemis-
try20 make it likely that radial radioisotope assay systems will
immunodiffusion and become commercially available. If so, detection of serum-M.G.B. may become important in carrier detection and hence in the control of Duchenne muscular dystrophy.
Hypothesis MIGRAINE: A BLOOD DISORDER? EDDA HANINGTON Wellcome Trust, 1 Park Square West, London NW1, and Princess Margaret Migraine Clinic, 22 Charterhouse Square, London EC1
suggested that a primary abnormality of platelet function can account for the diverse clinical, biochemical, and pathological findings reported in migraine.
Summary
It is
INTRODUCTION
COMMON migraine is twice as common as classical migraine and is defined as recurrent headache affecting chiefly one side of the head and often associated with nausea and vomiting. In classical migraine these symptoms are preceded by premonitory signs, called an aura. These signs are usually visual and are followed by the onset of headache within about 15 minutes. Any hypothesis for migraine has to explain both the prodromal symptoms of classical migraine and the headache phase of the attack.
My hypothesis is that a platelet abnormality is the primary cause of migraine. This places migraine among the commonest disorders of the blood. The clinical, biochemical, and pathological findings in migraine can, I suggest, be related to this primary abnormality of platelet function. MIGRAINE AND MONOAMINES
Stress-the most common cause of migraine-includes anxiety, excitement, fatigue, anger, and exertion. In some patients changes in plasma-levels of cestradiol and progesterone are associated with migraine attacks, as are eating certain foods and fasting. The important clinical observation on the precipitating causes of migraine is that they are cumulative in effect and are linked with increased vasoactive-monoamine metabo-
Requests for reprints should be addressed to B.T.A., Medical Neurology Branch, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, Maryland 20014, U.S.A. REFERENCES 1. 2.
Gardner-Medwin, D. J. med. Genet. 1970, 7, 334. Hughes, R. C., Park, D. C., Parsons, M. E., O’Brien, M. D.
J. Neurol. Neurosurg. Psychiat. 1971, 34, 527. 3. McCormick, D., Allen, I. V. Ulster med.J. 1976, 45, 79. 4. Moser, H., Mumenthaler, M., Weismann, U. Schweiz. med. Wschr. 1971, 101, 537. 5. Rotthauwe, H. W., Kowalewski, S. Arch. Kinderheilk. 1973, 115, 333. 6. Mahoney, M. J., Haseltine, F. P., Hobbins, J. C., Banker, B. Q., Casky, T., Golbus, M. S. New Engl. J. Med. 1977, 297, 968. 7. Kagen, L., Scheidt, S., Roberts, L., Porter, A., Saul, H. Am. J. Med. 1975, 58, 177. 8. Rowland, L. P., Layzer, R. B., Kagen, L. J. Archs Neurol., Chicago, 1968, 18, 272. 9. Adornato, B. T., Kagen, L., Engel, W. K. Unpublished. 10. Kagen, L. J., Scheidt, S., Butt, A.Am.J. Med. 1977, 62, 86. 11. Adornato, B. T., Engel, W. K., Kagen, L. J. Unpublished. 12. Mendell, J. R., Engel, W. K., Derrer, E. C. Nature, 1972, 239, 522. 13. Thomson, W. H. S. Myopathien; p. 219. Stuttgart, 1965. 14. Olerud, J. E., Homer, L. D., Carroll, H. W. New Engl. J. Med. 1975, 293, 483. 15. 16. 17.
Moser, H., Vogt, J. Lancet, 1974, ii, 661. Thompson, M. W., Murphy, E. G., McAlpine, T. J. J. Pediat. 1967, 71, 82. Gardner-Medwin, D., Pennington, R. J., Walton, J. N. neurol. Sci. 1971, 13,
459. 18. Kagen, L. J.J.Am. med.Ass. 1977, 237, 1448. 19. Rowland, L. P., Penn, A. S. Med. Clins N. Am. 1972, 56, 1233. 20. Boesken, W. H., Boesken, S., Maimer, A. Res. exp. Med. 1977, 171,
71.
lism. There appears to be a threshold level of monoamines in the blood which varies from person to person, but when the trigger is powerful enough and the threshold is exceeded then an attack of migraine follows. The vasoactive monoamines implicated in migraine
noradrenaline, adrenaline, 5-hydroxytryptamine (5-H.T.), tyramine, and p-phenylethylamine, which are broken down, at least partly, by the monoamine-oxidase (M.A.o.) group of enzymes. Platelet-M.A.o. activity is reduced in migraine patients and falls significantly during attacks. 12Platelet-m.A.o. activity increases with age, which may contribute to the lessening of the severity and frequency of migraine attacks with increasing age. In women, platelet-M.A.o. activity reaches a peak around the time of ovulation, with a nadir 5 to 11 days later.33 This may be linked with the high frequency of migraine attacks in some women just before menstruation. Changes in 5-H.T. metabolism in migraine have been extensively studied since they were first reported by Sicuteri and his colleagues4 in 1961. Plasma-5-H.T. levels rise before the onset of headache and fall sharply during the headache phase. Excretion of 5-hydroxyindoleacetic acid, a product of 5-H.T. metabolism, increases during attacks. 5’Reserpine, which has been used experimentally to induce headache in migraine patients, causes 5-H.T. release and depletes the blood of its 5-H.T’. content by the breakdown of 5-H.T. All the 5-H.T. in blood is contained in platelets and is released when they
are
aggregate. ROLE OF INCREASED PLATELET AGGREGATION
Hilton and Cumings first reported an increase in platelet aggregation in migraine in 1971.6 Since then a great deal of work in this area has been published, culminating in a paper by Deshmukh and Meyerwhich showed that platelet behaviour is a major factor in the pathogenesis of migraine and that the chief precipitating causes of migraine are closely linked with factors causing platelet aggregation. For example, stress results in an increase in plasma adrenaline, noradrenaline, and arachidonic acid, all of which can cause platelet aggregation.
