- Email: [email protected]
TERATOGENIC EFFECTS OF ORGANIC SOLVENTS
963 had ended in spontaneous abortion", it appears that the investigator was biased right from the start of the study. Exposure to organic solvents might just be a confounding factor, since only 12% of the cases were exposed during pregnancy. A multivariate analysis’ would have revealed the extent of interactions among the potential risk factors and the true causal relationship. Further epidemiological evidence is needed to confirm Dr
of 10% units or more (compared with the preoperative value) on two consecutive days was suggestive of thrombosis. When positive signs of DVT were found by the ’1-FUT screening, localisation of thrombi was done by the 1251-fibrinogen sum-coincidence technique. The decay scheme of 1251 is unique -in that the radionuclide decays by electron capture (EC) (100%) followed by 35 keV y-emission (7%) or by internal conversion (IC). On average during EC .074 K X-rays are emitted per disintegration, and in IC 0-67 K X-rays are emitted. In about half of the disintegrations, K X-rays (E=28.3 keV) are emitted after EC and after IC and these photons are emitted almost simultaneously. In a single detector, the coincident photons are registered together as a peak in the energy interval 44-70 keV. The ratio between the number of coincident photons detected and the total number of photons registered provides an index which is very sensitive to the distance between detector and source. This permits determination of the depth of thrombi from the skin surface of the count-rate
Holmberg’s findings. BOC Limited, Hammersmith House, London W6 9DX
HYPERKALÆMIC PARALYSIS RESEMBLING GUILLAIN-BARRÉ SYNDROME
lower limbs. The detector used was a 124 mm x 1-5 mm Nal (TI) crystal equipped with a brass collimator 50 mm long with an opening diameter of 40 mm and a thickness of 5 mm. The investigation was carried out in the low-background iron room at Maimo General Hospital. For comparison, phlebography was carried out immediately after depth localisation with the ’"1-FUT coincidence method. The conventional FUT was positive in 24 patients. In these
SIR,-We have seen a patient who presented with acute ascending paralysis resembling acute post-infectious polyneuritis (Guillain-Barre syndrome, GBS) in whom correction of electrolyte abnormalities caused complete resolution of symptoms.
patients the tzsI-fibrinogen sum-coincidence test detected 28 thrombi, 17 localised to muscle veins, 7 to tibial or fibular veins, 1 to the deep femoral vein, and 3 to superficial veins. There was virtually complete agreement between depth localisation by the 125I-fibrinogen sum-coincidence technique and that by phlebography. introduced the 125I-fibrinogen sum-coincidence routine in our department. This will decrease the number of phlebographies needed for detecting DVT after surgery and the new technique will allow repeated follow-ups of detected DVTs and the monitoring of both the course of even small thrombi (the significance of which is controversial) and the effect of treatment. We have
technique
now
as a
Department of Obstetrics and Gynæcology, Anæsthesia, and Radiation Physics, Malmö General Hospital, University of Lund, S-214 01 Malmö, Sweden
ULF ULMSTEN KURT BERNSTEIN
LARS JACOBSSON SÖREN MATTSSON BIRGER ASTEDT
TERATOGENIC EFFECTS OF ORGANIC SOLVENTS
SiR,-Dr Holmberg’s report (July 29, p. 177) illustrates the problems in the design and interpretation of a case-control study. It was a comparison of exposure, in early pregnancy, to 14 different
organic solvents in 118 women who gave birth stillborn) to children with congenital central-nervoussystem (CNS) defects and that in an equal number of controls. The controls were matched for only the date and the place of delivery. Although a statistically significant difference was shown in the history of exposure to organic solvents in the two groups, certain features cast doubt on the validity of the results. Dr Holmberg points out some-possible interviewer bias and the (live
or
differences between the 14 exposed cases or "case-mothers" and their controls in terms of illnesses (e.g., diabetes) and previous abortions. However, the report does not deal with the extent of the differences or similarities between all the 118 cases and their controls in terms of the variables known to be associated with congenital CNS defects-e.g., age, social class, parity. Although Dr Holmberg claims a similarity in parental age of the two groups, there is, in fact, a poor correlation between the parental ages of the 14 exposed cases and their controls; for example, in case no. 8, the parents were 42 and 44 whereas their controls were 20. To minimise the bias created by the mismatching of cases and controls, Dr Holmberg could have recruited at least three independent control groups. From the last
earlier
of the paper in two cases ... with similar exposure to organic solvents
sentence
pregnancies
K. SHEIKH
"
A previously healthy 38-year-old man had sustained rib fractures in a road-traffic accident 3 weeks before admission. Apart from mild discomfort he remained well until 2 weeks later when he began feeling generally unwell with anorexia and nausea. 24 h before admission he noticed that his legs gave way under him while, walking. He was able to resume walking but only with assistance. 4 h later he could no longer support his own weight and after a further 8 h was unable to move his legs. At that stage he was admitted to hospital. He had been unable to void urine for the previous 24 h despite experiencing the sensation of bladder fullness. On examination he was normotensive. He was tender over the 3rd to 6th ribs on the right side. His bladder was palpable above the symphysis pubis and catheterisation yielded 500 ml of clear urine with one hyaline cast per high-power field. He had a complete flaccid paralysis of both lower limbs with normal power in the upper limbs. His deep tendon reflexes were normal in the upper limbs, and absent in the lower limbs. No sensory abnormalities were noted and his mental state was clear. There was no relevant family history. During the first 3 h of his admission he rapidly deteriorated to global weakness of both upper limbs and early respiratory weakness. An electrocardiogram showed changes consistent with hyperkalaemia and 50 ml of 50% dextrose plus 10 units of soluble insulin were administered intravenously. Muscle strength in both upper limbs improved 30 min later. On admission he had a serum sodium of 110 mmol/1, potassium 9-3 mmol/1, bicarbonate 17 mmol/1, urea 26-8 mmol/1 (161 mg/dl), and creatinine 1250 µmol/l (13.8 mg/dl). Urine osmolality was 260 mmol/1. An arterial blood-sample, taken with the patient breathing room air, showed a pH of 7-38 (normal 7-36-7-42), POz of 12.2 kPa (normal 12.0-14.0), and a PCOz of 3.2 kPa (normal 4.5-6.1) (1 kPa=7.5mm Hg). Peritoneal dialysis was started with isotonic potassium-free dialysate, and within 8 h the patient’s muscle strength and deep tendon reflexes were normal. At that stage his serum sodium was 116 mmol/1, potassium 5-7 mmol/1, bicarbonate 17-6 mmol/l, urea 23-0 mmol/1, and creatinine 1043 µmol/l. Peritoneal dialysis was discontinued after 24 h. Investigations, including renal biopsy, failed to reveal the cause of this patient’s renal failure, and its relation to the road-traffic accident remains unclear. His renal function gradually returned to normal and has remained thus.
The clinical picture of acute ascending paralysis in the presence of clear consciousness and without sensory signs is
strongly suggestive 1. Breslow
of
acute
idiopathic polyneuritis (GBS).2
NE, Day NE, Halvorsen KT, Prentice RL, Sabai C. Estimation of multiple relative risk functions in matched case—control studies. Am J Epidemiol 1978; 108. 299—307. 2. Brain, Walton JN. Brain’s disease of the nervous system. London: Oxford University Press, 1969: 713.
of 10% units or more (compared with the preoperative value) on two consecutive days was suggestive of thrombosis. When positive signs of DVT were found by the ’1-FUT screening, localisation of thrombi was done by the 1251-fibrinogen sum-coincidence technique. The decay scheme of 1251 is unique -in that the radionuclide decays by electron capture (EC) (100%) followed by 35 keV y-emission (7%) or by internal conversion (IC). On average during EC .074 K X-rays are emitted per disintegration, and in IC 0-67 K X-rays are emitted. In about half of the disintegrations, K X-rays (E=28.3 keV) are emitted after EC and after IC and these photons are emitted almost simultaneously. In a single detector, the coincident photons are registered together as a peak in the energy interval 44-70 keV. The ratio between the number of coincident photons detected and the total number of photons registered provides an index which is very sensitive to the distance between detector and source. This permits determination of the depth of thrombi from the skin surface of the count-rate
Holmberg’s findings. BOC Limited, Hammersmith House, London W6 9DX
HYPERKALÆMIC PARALYSIS RESEMBLING GUILLAIN-BARRÉ SYNDROME
lower limbs. The detector used was a 124 mm x 1-5 mm Nal (TI) crystal equipped with a brass collimator 50 mm long with an opening diameter of 40 mm and a thickness of 5 mm. The investigation was carried out in the low-background iron room at Maimo General Hospital. For comparison, phlebography was carried out immediately after depth localisation with the ’"1-FUT coincidence method. The conventional FUT was positive in 24 patients. In these
SIR,-We have seen a patient who presented with acute ascending paralysis resembling acute post-infectious polyneuritis (Guillain-Barre syndrome, GBS) in whom correction of electrolyte abnormalities caused complete resolution of symptoms.
patients the tzsI-fibrinogen sum-coincidence test detected 28 thrombi, 17 localised to muscle veins, 7 to tibial or fibular veins, 1 to the deep femoral vein, and 3 to superficial veins. There was virtually complete agreement between depth localisation by the 125I-fibrinogen sum-coincidence technique and that by phlebography. introduced the 125I-fibrinogen sum-coincidence routine in our department. This will decrease the number of phlebographies needed for detecting DVT after surgery and the new technique will allow repeated follow-ups of detected DVTs and the monitoring of both the course of even small thrombi (the significance of which is controversial) and the effect of treatment. We have
technique
now
as a
Department of Obstetrics and Gynæcology, Anæsthesia, and Radiation Physics, Malmö General Hospital, University of Lund, S-214 01 Malmö, Sweden
ULF ULMSTEN KURT BERNSTEIN
LARS JACOBSSON SÖREN MATTSSON BIRGER ASTEDT
TERATOGENIC EFFECTS OF ORGANIC SOLVENTS
SiR,-Dr Holmberg’s report (July 29, p. 177) illustrates the problems in the design and interpretation of a case-control study. It was a comparison of exposure, in early pregnancy, to 14 different
organic solvents in 118 women who gave birth stillborn) to children with congenital central-nervoussystem (CNS) defects and that in an equal number of controls. The controls were matched for only the date and the place of delivery. Although a statistically significant difference was shown in the history of exposure to organic solvents in the two groups, certain features cast doubt on the validity of the results. Dr Holmberg points out some-possible interviewer bias and the (live
or
differences between the 14 exposed cases or "case-mothers" and their controls in terms of illnesses (e.g., diabetes) and previous abortions. However, the report does not deal with the extent of the differences or similarities between all the 118 cases and their controls in terms of the variables known to be associated with congenital CNS defects-e.g., age, social class, parity. Although Dr Holmberg claims a similarity in parental age of the two groups, there is, in fact, a poor correlation between the parental ages of the 14 exposed cases and their controls; for example, in case no. 8, the parents were 42 and 44 whereas their controls were 20. To minimise the bias created by the mismatching of cases and controls, Dr Holmberg could have recruited at least three independent control groups. From the last
earlier
of the paper in two cases ... with similar exposure to organic solvents
sentence
pregnancies
K. SHEIKH
"
A previously healthy 38-year-old man had sustained rib fractures in a road-traffic accident 3 weeks before admission. Apart from mild discomfort he remained well until 2 weeks later when he began feeling generally unwell with anorexia and nausea. 24 h before admission he noticed that his legs gave way under him while, walking. He was able to resume walking but only with assistance. 4 h later he could no longer support his own weight and after a further 8 h was unable to move his legs. At that stage he was admitted to hospital. He had been unable to void urine for the previous 24 h despite experiencing the sensation of bladder fullness. On examination he was normotensive. He was tender over the 3rd to 6th ribs on the right side. His bladder was palpable above the symphysis pubis and catheterisation yielded 500 ml of clear urine with one hyaline cast per high-power field. He had a complete flaccid paralysis of both lower limbs with normal power in the upper limbs. His deep tendon reflexes were normal in the upper limbs, and absent in the lower limbs. No sensory abnormalities were noted and his mental state was clear. There was no relevant family history. During the first 3 h of his admission he rapidly deteriorated to global weakness of both upper limbs and early respiratory weakness. An electrocardiogram showed changes consistent with hyperkalaemia and 50 ml of 50% dextrose plus 10 units of soluble insulin were administered intravenously. Muscle strength in both upper limbs improved 30 min later. On admission he had a serum sodium of 110 mmol/1, potassium 9-3 mmol/1, bicarbonate 17 mmol/1, urea 26-8 mmol/1 (161 mg/dl), and creatinine 1250 µmol/l (13.8 mg/dl). Urine osmolality was 260 mmol/1. An arterial blood-sample, taken with the patient breathing room air, showed a pH of 7-38 (normal 7-36-7-42), POz of 12.2 kPa (normal 12.0-14.0), and a PCOz of 3.2 kPa (normal 4.5-6.1) (1 kPa=7.5mm Hg). Peritoneal dialysis was started with isotonic potassium-free dialysate, and within 8 h the patient’s muscle strength and deep tendon reflexes were normal. At that stage his serum sodium was 116 mmol/1, potassium 5-7 mmol/1, bicarbonate 17-6 mmol/l, urea 23-0 mmol/1, and creatinine 1043 µmol/l. Peritoneal dialysis was discontinued after 24 h. Investigations, including renal biopsy, failed to reveal the cause of this patient’s renal failure, and its relation to the road-traffic accident remains unclear. His renal function gradually returned to normal and has remained thus.
The clinical picture of acute ascending paralysis in the presence of clear consciousness and without sensory signs is
strongly suggestive 1. Breslow
of
acute
idiopathic polyneuritis (GBS).2
NE, Day NE, Halvorsen KT, Prentice RL, Sabai C. Estimation of multiple relative risk functions in matched case—control studies. Am J Epidemiol 1978; 108. 299—307. 2. Brain, Walton JN. Brain’s disease of the nervous system. London: Oxford University Press, 1969: 713.