- Email: [email protected]
ASSESSMENT OF FETAL RENAL RESERVE IN LOW LEVEL OBSTRUCTIVE UROPATHY
281
organisms present was small or that the organisms were unevenly distributed, perhaps in the form of a microcolony-or that the
The source flocks were predominantly of the battery type and ranged in size from 300-30 000 birds (table).
remaining organisms had succumbed to the action of antibacterial
A further 274 eggs from some of the above farms were examined 2-4 weeks after the initial positive isolations. All were salmonella negative. It was also not possible to recover the organism from homogenised contents of salmonella-positive eggs if they had been stored at either +4°C or - 20"C for 48 h. These results accord with those of Dr Paul and Dr Batchelor and confirm that some infected egg-laying flocks have the capacity to lay a significant proportion of contaminated eggs. It would also appear that the production of infected eggs is intermittent since the subsequent examination of eggs from the implicated flocks failed to demonstrate salmonella even though one flock was found to be
substances in the egg. The intensive monitoring of a small flock of free-range hens had demonstrated that even in a flock associated with human cases, the proportion of contaminated eggs is small (5/360,-4%) and that the number of organisms present in those eggs was probably small. This raises the possibility that, because of the high fat content of the yolk, the human infective dose is small, as in the S napoli outbreak caused by contaminated chocolate.’ The increase in numbers of organisms in the mousse caused by the failure to store this high-risk food under refrigeration would probably not have been sufficient for the S enteritidis PT4 present to reach the large numbers classically associated with salmonella food poisoning. It is surprising that the school’s domestic science department was unaware of the Department of Health’s warning (Sept 9) about raw egg-containing dishes (raw eggs were not being used in the school kitchen) and that it failed to ensure the refrigeration of this on-risk food. Even with eggs which are as likely as these to have been the source of infection, it is often necessary to examine large numbers of eggs (several hundreds) to fmd a positive example. The microbiology of the egg may not be as straightforward as that of other types of food. This was vividly demonstrated in some experimental infections with S menston in the 1960s/ to which the current problem with S enteritidis PT4 in laying hens bears a remarkable resemblance. Although the relative roles of transovarian infection, migration of salmonella through the soft or intact shells of eggs to the contents, or contamination from the shell in the kitchen are academic to the patient, the fundamental problem is that the flocks and some of their eggs are infected and control measures are urgently required. We thank Mr T. P. Liggins, environmental health officer, East Yorkshire Borough Council; Mrs S. A. Hopper, Lincoln Veterinary Investigation Centre; and the affected family, for their enthusiastic assistance.
positive at slaughter. We thank the local authorities in Devon and the staff at the Veterinary Investigation Centre, Starcross, for their help in tracing the flocks implicated in the outbreaks. T.
Public Health Laboratory, Heavitree, Exeter EX2 5AD
J. HUMPHREY
J. G. CRUICKSHANK
Division of Entenc Pathogens, Central Public Health Laboratory, London NW9
B. ROWE
ASSESSMENT OF FETAL RENAL RESERVE IN LOW LEVEL OBSTRUCTIVE UROPATHY
SIR,-In fetal lower urinary
tract
obstruction, obstetric
depends on the assessment of fetal renal function. Oligohydramnios generally suggests poor renal function but is not a sensitive enough sign to be used as a definitive test. Ultrasound can identify changes consistent with cystic dysplasia (type IV)1 within the kidney parenchyma, including cortical cysts (specificity 100%) and increased echogenicity (specificity 80%, sensitivity 73%).2 Harrison et aP obtained fetal urine by transabdominal sampling, and their preliminary results suggested that levels of sodium below 100 mmol/1, chloride below 90 mmol/1, and osmolality less than
management
Public Health Laboratory, Hull Royal Infirmary, Hull HU3 2J2
S. L. MAWER G. E. SPAIN
210 mosm/1
Division of Enteric Pathogens, Central Public Health Laboratory, London NW9
B. ROWE
examination and fetal urine studies. 21 cases of low level urinary tract obstruction, defined as megacystis with or without hydronephrosis or hydroureters, were prospectively followed up between 1983 and 1988. Ultrasound evaluation was obtained in all cases and fetal urine electrolytes were measured in 12 cases by ultrasound-guided percutaneous bladder puncture. 4 of the fetuses had normal urinary electrolytes. 2 were delivered and had normal neonatal renal function and 2 pregnancies were terminated. Necropsy revealed hydronephrosis without cystic dysplasia. There were 8 cases with abnormal electrolyte results. Cystic dysplasia was confirmed at necropsy in 7 cases. In the eighth
1. Gill ON, Bartlett CLR, Sockett PN, et al Outbreak of Salmonella napoli infection caused by contaminated chocolate bars. Lancet 1983; i: 574-77. 2. Gordon RF, Tucker JF. The epizootiology of Salmonella menston infection of fowls and the effect of feeding poultry food artificially infected with salmonella. Br Poultry Sci 1965; 6: 251-64.
SIR,-In the period July to December, 1988, the Exeter Public Health Laboratory investigated six outbreaks of egg-associated S enteritidis PT4 infection. In four it was possible to examine eggs either from the same batch as that implicated in the outbreak or from the same source(s). They were examined using standard pre-enrichment and selective techniques, the shells being disinfected with alcohol after testing and before the contents were removed. 17 (8-8%) of 194 eggs were positive for S enteritidis PT4. In 6 the organism was isolated from the contents only, in 10 the shell alone was positive, and in one egg S enteritidis PT4 was recovered from both sites.
correlated with normal neonatal renal function.
Conversely, higher values were associated with poor renal function at birth and cystic dysplasia was usually present. We present our experience in assessing renal function in utero via ultrasound
150
150
300
140 -
140 -
280-
;
130
260
!
. .
130 120 -
’
240-
-
120
110
**
*
..t
«
110 I 220 - - - - - - - 200
100 - - - - - 100 -
8
1
CONTAMINATION OF INTACT HENS’ EGGS WITH S ENTERITIDIS PT4 90
90 -
80
0
—
-
’
’
-* " ’ * 180 160-
80 0 °
70 -
70-
60 -
60 -
50
"
4o
140120-0 0
8
50 "
40
Sodium
Chionde
100 80
Osmolality
Urinary sodium (mmol/dl), chloride (mmol/dl), and osmolality (mosm/1) in cases of fetal lower urinary tract obstruction. *Flocks C, D, and E were suppliers to wholesaler implicated as source of eggs in one family outbreak. tNumbers in parentheses are numbers positive in contents, shell, or both, respectively
.
=pathological findings
0 = normal renal function lines show cut-off level .3
at
at
necropsy consistent with cystic dysplasia ; or normal findings at necropsy. Dashed
birth
282 case, pathological examination showed no cystic dysplasia but the glomerulogenic zone was absent, which may explain the abnormal
electrolytes. Of the 21 cases, 11had normal prenatal ultrasound fmdings in both kidneys. At necropsy, 9 had normal neonatal renal function or absence of cystic dysplasia and 2 had bilateral cystic dysplasia, representing false negative ultrasound diagnoses. 10 cases had abnormal prenatal ultrasound findings. In 1 case the left kidney had isolated hydronephrosis whereas the right kidney showed cystic dysplasia. This was confirmed in the neonatal period. 9 cases had abnormal prenatal ultrasound findings bilaterally, 7 of which were confirmed at necropsy. In the eighth case, permission for necropsy was refused, but ultrasound examination of the newborn infant revealed bilateral cystic dysplasia. In the final case unilateral cystic dysplasia was found at necropsy, a partly incorrect diagnosis. The correlation between electrolyte values and outcome in our series was 100% (we accept the small numbers and the time interval between prenatal and postnatal assessment) (figure). Two errors (false negatives) occurred in renal function assessment by ultrasound examination only. In 1 case urinary electrolytes were not measured; in the second the abnormal urinary electrolyte results more accurately reflected the pathological diagnosis. Wilkins et al’ did not find as strong a correlation as we did, perhaps because the aetiology of the obstruction varied or different criteria were used in
sonography. Because oligohydramnios can preclude an accurate ultrasound assessment of the fetal kidneys, measurement of fetal urine electrolytes may improve diagnostic accuracy. Based on our experience, fetal urine electrolyte measurement should be part of the routine evaluation of a fetus with a low level obstructive uropathy. Prenatal counselling should be given according to the clinical situation. R. R. receives Health.
a
Physician Scientist Award from the National Institutes of
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06510, USA 1 Potter EL Normal and abnormal
PETER A. GRANNUM ALESSANDRO GHIDINI ANGELA SCIOSCIA JOSHUA A. COPEL ROBERTO ROMERO JOHN C. HOBBINS
development of the kidney. Chicago:
deformities.2 To avoid confusion, the type of atlantoaxial instability should be specified. In normal individuals with the rare traumatic anterior atlantoaxial subluxation as well as in rheumatoid patients, who commonly have cervical instabilities, anterior atlantoaxial subluxation is benign, causing C2-nerve-related occipitocervical headacheand, rarely, signs of myelopathy, which are usually limited to glove-like sensory loss in the hands and increased tendon reflexes.2 To date, after having followed up more than 300 rheumatoid patients and a few traumatic patients with anterior type atlantoaxial subluxation, we have not seen cases of sudden death or
paralysis. You point out that some individuals lost the atlantoaxial instability over time. Anterior atlantoaxial subluxation is sometimes self-limiting. With increasing cranial subluxation, the amplitude of atlantoaxial instability diminishes.2 It is usually the advanced cranial subluxation of the odontoid process that
causes more severe
neurological changes.2,s Gallie-type Cl-C2 fusion is an effective treatment for symptomatic anterior atlantoaxial subluxation. In patients with Down syndrome operative treatment is, however, seldom necessary. Department of Medicine, University Central Hospital, 00189 Helsinki, Finland Fourth
YRJÖ T. KONTTINEN
Orthopaedic Hospital of Invalid Foundation,
SEPPO SANTAVIRTA
Helsinki
1. Konttinen
YT, Bergroth V, Santavirta S, et al. Inflammatory involvement of the spine ligaments in rheumatoid arthritis patients with atlantoaxial subluxations. J Rheumatol 1987; 14: 531-34. 2. Santavirta S, Kankaanpaa U, Sandelin J. Evaluation of patients with rheumatoid cervical spine. Scand J Rheumatol 1987; 16: 9-16. 3. Santavirta S, Slatis P, Kankaanpäa U, et al. Treatment of the cervical spine in rheumatoid arthritis. J Bone Joint Surg [Am] 1988; 70: 658-67. 4. Burke SW, French HG, Roberts JM, et al. Chronic atlantoaxial instability in Down syndrome. J Bone Joint Surg 1985; 67: 1356-60. 5. Santavirta S, Hallikainen D, Paukku P, et al Atlantoaxial facet joint arthritis in the rheumatoid cervical spine: a panoramic zonography study. J Rheumatol 1988, 15: cervical
217-23.
S, Sandelin J, Slätis P. Postenor atlantoaxial subluxation in rheumatoid arthritis. Acta Orthop Scand 1985; 56: 298-301. 7 Knottinen YT, Santavirta S, Grönblad M, et al. Pain in anterior atlantoaxial subluxation. J Rheumatol (in press). 6. Santavirta
Year Book
Medical Publishers, 1972. 2. Mahony BS, Filly RA, Callen PW,
et al. Sonographic evaluation of fetal renal dysplasia. Radiology 1984, 152: 143. 3. Glick PL, Harrison MR, Golbus MS, et al. Management of the fetus with congenital hydronephrosis II: prognostic criteria and selection for treatment. J Pediatr Surg 1985, 20: 376 4 Wilkins IA, Chitkara U, Lynch L, et al. The nonpredictive value of fetal urinary electrolytes: preliminary report of outcomes and correlations with pathologic diagnosis. Am J Obstet Gynecol 1987; 157: 694.
ATLANTOAXIAL INSTABILITY IN DOWN SYNDROME 7 editorial uses the term atlantoaxial instability specifying its type. You also say that the incidence of neurological damage due to atlantoaxial instability in normal
SiR,—Your Jan
without
individuals from any other cause is unknown. Anterior atlantoaxial dislocation is secondary to the changes in the collagenous tissue that cause laxity in the cervical spine ligaments.1,2 When the transverse ligaments rupture minimum subluxation is possible. When the apical and alar ligaments also become stretched, considerable instability occurs in the atlantoaxial joint, with amplitudes varying by up to 22 mm.2.3 Anterior type atlantoaxial subluxation is the cervical instability usually observed in patients with Down syndrome.’ In contrast to anterior atlantoaxial subluxation, where soft tissues play an important part in the pathogenesis,’ cranial subluxation of the odontoid process5 develops later and is caused by bilateral destruction of the articular masses in the atlantoaxial facet joints. In addition to these two types of atlantoaxial subluxationfour others should be mentioned: posterior atlantoaxial, lateral atlantoaxial, and rotatory atlantoaxial subluxations and non-reducible head-tilt
PATENT FORAMEN OVALE OR LEFT ATRIAL THROMBI IN UNEXPLAINED ARTERIAL EMBOLISM
SIR,-Lechat et all and Webster et al2 found a high prevalence of patent foramen ovale in patients with non-haemorrhagic stroke and concluded that paradoxical embolism may be a major cause of stroke. Patent foramen ovale was sought by transthoracic contrast echocardiography but we do not think that this is a reliable method for confirming or excluding other cardiac sources of embolism. Small thrombi and isolated thrombi in the left atrial appendage are usually missed by the transthoracic approach. They can, however, easily be detected by transoesophageal echocardiography,3 which provides a good "view" of both atria, the atrial septum, and the valves in virtually all patients 4 Transoesophageal echocardiography can detect a patent foramen ovale when used with doppler and carries hardly any risk.** We have studied 85 men and 47 women aged 54 (SD 16) years with unexplained peripheral embolism (38) and/or stroke most probably due to a cerebral embolic event (94). All were examined by a
MAJOR ECHOCARDIOGRAPHIC FINDINGS
IN PATIENTS WITH
UNEXPLAINED EMBOLISM
PFO = patent foramen ovale, LASEC left atrial spontaneous echo contrast, LA LV left atnum and ventricle, LAA left atrial appendage. *On 21 panents only. =
=
=
organisms present was small or that the organisms were unevenly distributed, perhaps in the form of a microcolony-or that the
The source flocks were predominantly of the battery type and ranged in size from 300-30 000 birds (table).
remaining organisms had succumbed to the action of antibacterial
A further 274 eggs from some of the above farms were examined 2-4 weeks after the initial positive isolations. All were salmonella negative. It was also not possible to recover the organism from homogenised contents of salmonella-positive eggs if they had been stored at either +4°C or - 20"C for 48 h. These results accord with those of Dr Paul and Dr Batchelor and confirm that some infected egg-laying flocks have the capacity to lay a significant proportion of contaminated eggs. It would also appear that the production of infected eggs is intermittent since the subsequent examination of eggs from the implicated flocks failed to demonstrate salmonella even though one flock was found to be
substances in the egg. The intensive monitoring of a small flock of free-range hens had demonstrated that even in a flock associated with human cases, the proportion of contaminated eggs is small (5/360,-4%) and that the number of organisms present in those eggs was probably small. This raises the possibility that, because of the high fat content of the yolk, the human infective dose is small, as in the S napoli outbreak caused by contaminated chocolate.’ The increase in numbers of organisms in the mousse caused by the failure to store this high-risk food under refrigeration would probably not have been sufficient for the S enteritidis PT4 present to reach the large numbers classically associated with salmonella food poisoning. It is surprising that the school’s domestic science department was unaware of the Department of Health’s warning (Sept 9) about raw egg-containing dishes (raw eggs were not being used in the school kitchen) and that it failed to ensure the refrigeration of this on-risk food. Even with eggs which are as likely as these to have been the source of infection, it is often necessary to examine large numbers of eggs (several hundreds) to fmd a positive example. The microbiology of the egg may not be as straightforward as that of other types of food. This was vividly demonstrated in some experimental infections with S menston in the 1960s/ to which the current problem with S enteritidis PT4 in laying hens bears a remarkable resemblance. Although the relative roles of transovarian infection, migration of salmonella through the soft or intact shells of eggs to the contents, or contamination from the shell in the kitchen are academic to the patient, the fundamental problem is that the flocks and some of their eggs are infected and control measures are urgently required. We thank Mr T. P. Liggins, environmental health officer, East Yorkshire Borough Council; Mrs S. A. Hopper, Lincoln Veterinary Investigation Centre; and the affected family, for their enthusiastic assistance.
positive at slaughter. We thank the local authorities in Devon and the staff at the Veterinary Investigation Centre, Starcross, for their help in tracing the flocks implicated in the outbreaks. T.
Public Health Laboratory, Heavitree, Exeter EX2 5AD
J. HUMPHREY
J. G. CRUICKSHANK
Division of Entenc Pathogens, Central Public Health Laboratory, London NW9
B. ROWE
ASSESSMENT OF FETAL RENAL RESERVE IN LOW LEVEL OBSTRUCTIVE UROPATHY
SIR,-In fetal lower urinary
tract
obstruction, obstetric
depends on the assessment of fetal renal function. Oligohydramnios generally suggests poor renal function but is not a sensitive enough sign to be used as a definitive test. Ultrasound can identify changes consistent with cystic dysplasia (type IV)1 within the kidney parenchyma, including cortical cysts (specificity 100%) and increased echogenicity (specificity 80%, sensitivity 73%).2 Harrison et aP obtained fetal urine by transabdominal sampling, and their preliminary results suggested that levels of sodium below 100 mmol/1, chloride below 90 mmol/1, and osmolality less than
management
Public Health Laboratory, Hull Royal Infirmary, Hull HU3 2J2
S. L. MAWER G. E. SPAIN
210 mosm/1
Division of Enteric Pathogens, Central Public Health Laboratory, London NW9
B. ROWE
examination and fetal urine studies. 21 cases of low level urinary tract obstruction, defined as megacystis with or without hydronephrosis or hydroureters, were prospectively followed up between 1983 and 1988. Ultrasound evaluation was obtained in all cases and fetal urine electrolytes were measured in 12 cases by ultrasound-guided percutaneous bladder puncture. 4 of the fetuses had normal urinary electrolytes. 2 were delivered and had normal neonatal renal function and 2 pregnancies were terminated. Necropsy revealed hydronephrosis without cystic dysplasia. There were 8 cases with abnormal electrolyte results. Cystic dysplasia was confirmed at necropsy in 7 cases. In the eighth
1. Gill ON, Bartlett CLR, Sockett PN, et al Outbreak of Salmonella napoli infection caused by contaminated chocolate bars. Lancet 1983; i: 574-77. 2. Gordon RF, Tucker JF. The epizootiology of Salmonella menston infection of fowls and the effect of feeding poultry food artificially infected with salmonella. Br Poultry Sci 1965; 6: 251-64.
SIR,-In the period July to December, 1988, the Exeter Public Health Laboratory investigated six outbreaks of egg-associated S enteritidis PT4 infection. In four it was possible to examine eggs either from the same batch as that implicated in the outbreak or from the same source(s). They were examined using standard pre-enrichment and selective techniques, the shells being disinfected with alcohol after testing and before the contents were removed. 17 (8-8%) of 194 eggs were positive for S enteritidis PT4. In 6 the organism was isolated from the contents only, in 10 the shell alone was positive, and in one egg S enteritidis PT4 was recovered from both sites.
correlated with normal neonatal renal function.
Conversely, higher values were associated with poor renal function at birth and cystic dysplasia was usually present. We present our experience in assessing renal function in utero via ultrasound
150
150
300
140 -
140 -
280-
;
130
260
!
. .
130 120 -
’
240-
-
120
110
**
*
..t
«
110 I 220 - - - - - - - 200
100 - - - - - 100 -
8
1
CONTAMINATION OF INTACT HENS’ EGGS WITH S ENTERITIDIS PT4 90
90 -
80
0
—
-
’
’
-* " ’ * 180 160-
80 0 °
70 -
70-
60 -
60 -
50
"
4o
140120-0 0
8
50 "
40
Sodium
Chionde
100 80
Osmolality
Urinary sodium (mmol/dl), chloride (mmol/dl), and osmolality (mosm/1) in cases of fetal lower urinary tract obstruction. *Flocks C, D, and E were suppliers to wholesaler implicated as source of eggs in one family outbreak. tNumbers in parentheses are numbers positive in contents, shell, or both, respectively
.
=pathological findings
0 = normal renal function lines show cut-off level .3
at
at
necropsy consistent with cystic dysplasia ; or normal findings at necropsy. Dashed
birth
282 case, pathological examination showed no cystic dysplasia but the glomerulogenic zone was absent, which may explain the abnormal
electrolytes. Of the 21 cases, 11had normal prenatal ultrasound fmdings in both kidneys. At necropsy, 9 had normal neonatal renal function or absence of cystic dysplasia and 2 had bilateral cystic dysplasia, representing false negative ultrasound diagnoses. 10 cases had abnormal prenatal ultrasound findings. In 1 case the left kidney had isolated hydronephrosis whereas the right kidney showed cystic dysplasia. This was confirmed in the neonatal period. 9 cases had abnormal prenatal ultrasound findings bilaterally, 7 of which were confirmed at necropsy. In the eighth case, permission for necropsy was refused, but ultrasound examination of the newborn infant revealed bilateral cystic dysplasia. In the final case unilateral cystic dysplasia was found at necropsy, a partly incorrect diagnosis. The correlation between electrolyte values and outcome in our series was 100% (we accept the small numbers and the time interval between prenatal and postnatal assessment) (figure). Two errors (false negatives) occurred in renal function assessment by ultrasound examination only. In 1 case urinary electrolytes were not measured; in the second the abnormal urinary electrolyte results more accurately reflected the pathological diagnosis. Wilkins et al’ did not find as strong a correlation as we did, perhaps because the aetiology of the obstruction varied or different criteria were used in
sonography. Because oligohydramnios can preclude an accurate ultrasound assessment of the fetal kidneys, measurement of fetal urine electrolytes may improve diagnostic accuracy. Based on our experience, fetal urine electrolyte measurement should be part of the routine evaluation of a fetus with a low level obstructive uropathy. Prenatal counselling should be given according to the clinical situation. R. R. receives Health.
a
Physician Scientist Award from the National Institutes of
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06510, USA 1 Potter EL Normal and abnormal
PETER A. GRANNUM ALESSANDRO GHIDINI ANGELA SCIOSCIA JOSHUA A. COPEL ROBERTO ROMERO JOHN C. HOBBINS
development of the kidney. Chicago:
deformities.2 To avoid confusion, the type of atlantoaxial instability should be specified. In normal individuals with the rare traumatic anterior atlantoaxial subluxation as well as in rheumatoid patients, who commonly have cervical instabilities, anterior atlantoaxial subluxation is benign, causing C2-nerve-related occipitocervical headacheand, rarely, signs of myelopathy, which are usually limited to glove-like sensory loss in the hands and increased tendon reflexes.2 To date, after having followed up more than 300 rheumatoid patients and a few traumatic patients with anterior type atlantoaxial subluxation, we have not seen cases of sudden death or
paralysis. You point out that some individuals lost the atlantoaxial instability over time. Anterior atlantoaxial subluxation is sometimes self-limiting. With increasing cranial subluxation, the amplitude of atlantoaxial instability diminishes.2 It is usually the advanced cranial subluxation of the odontoid process that
causes more severe
neurological changes.2,s Gallie-type Cl-C2 fusion is an effective treatment for symptomatic anterior atlantoaxial subluxation. In patients with Down syndrome operative treatment is, however, seldom necessary. Department of Medicine, University Central Hospital, 00189 Helsinki, Finland Fourth
YRJÖ T. KONTTINEN
Orthopaedic Hospital of Invalid Foundation,
SEPPO SANTAVIRTA
Helsinki
1. Konttinen
YT, Bergroth V, Santavirta S, et al. Inflammatory involvement of the spine ligaments in rheumatoid arthritis patients with atlantoaxial subluxations. J Rheumatol 1987; 14: 531-34. 2. Santavirta S, Kankaanpaa U, Sandelin J. Evaluation of patients with rheumatoid cervical spine. Scand J Rheumatol 1987; 16: 9-16. 3. Santavirta S, Slatis P, Kankaanpäa U, et al. Treatment of the cervical spine in rheumatoid arthritis. J Bone Joint Surg [Am] 1988; 70: 658-67. 4. Burke SW, French HG, Roberts JM, et al. Chronic atlantoaxial instability in Down syndrome. J Bone Joint Surg 1985; 67: 1356-60. 5. Santavirta S, Hallikainen D, Paukku P, et al Atlantoaxial facet joint arthritis in the rheumatoid cervical spine: a panoramic zonography study. J Rheumatol 1988, 15: cervical
217-23.
S, Sandelin J, Slätis P. Postenor atlantoaxial subluxation in rheumatoid arthritis. Acta Orthop Scand 1985; 56: 298-301. 7 Knottinen YT, Santavirta S, Grönblad M, et al. Pain in anterior atlantoaxial subluxation. J Rheumatol (in press). 6. Santavirta
Year Book
Medical Publishers, 1972. 2. Mahony BS, Filly RA, Callen PW,
et al. Sonographic evaluation of fetal renal dysplasia. Radiology 1984, 152: 143. 3. Glick PL, Harrison MR, Golbus MS, et al. Management of the fetus with congenital hydronephrosis II: prognostic criteria and selection for treatment. J Pediatr Surg 1985, 20: 376 4 Wilkins IA, Chitkara U, Lynch L, et al. The nonpredictive value of fetal urinary electrolytes: preliminary report of outcomes and correlations with pathologic diagnosis. Am J Obstet Gynecol 1987; 157: 694.
ATLANTOAXIAL INSTABILITY IN DOWN SYNDROME 7 editorial uses the term atlantoaxial instability specifying its type. You also say that the incidence of neurological damage due to atlantoaxial instability in normal
SiR,—Your Jan
without
individuals from any other cause is unknown. Anterior atlantoaxial dislocation is secondary to the changes in the collagenous tissue that cause laxity in the cervical spine ligaments.1,2 When the transverse ligaments rupture minimum subluxation is possible. When the apical and alar ligaments also become stretched, considerable instability occurs in the atlantoaxial joint, with amplitudes varying by up to 22 mm.2.3 Anterior type atlantoaxial subluxation is the cervical instability usually observed in patients with Down syndrome.’ In contrast to anterior atlantoaxial subluxation, where soft tissues play an important part in the pathogenesis,’ cranial subluxation of the odontoid process5 develops later and is caused by bilateral destruction of the articular masses in the atlantoaxial facet joints. In addition to these two types of atlantoaxial subluxationfour others should be mentioned: posterior atlantoaxial, lateral atlantoaxial, and rotatory atlantoaxial subluxations and non-reducible head-tilt
PATENT FORAMEN OVALE OR LEFT ATRIAL THROMBI IN UNEXPLAINED ARTERIAL EMBOLISM
SIR,-Lechat et all and Webster et al2 found a high prevalence of patent foramen ovale in patients with non-haemorrhagic stroke and concluded that paradoxical embolism may be a major cause of stroke. Patent foramen ovale was sought by transthoracic contrast echocardiography but we do not think that this is a reliable method for confirming or excluding other cardiac sources of embolism. Small thrombi and isolated thrombi in the left atrial appendage are usually missed by the transthoracic approach. They can, however, easily be detected by transoesophageal echocardiography,3 which provides a good "view" of both atria, the atrial septum, and the valves in virtually all patients 4 Transoesophageal echocardiography can detect a patent foramen ovale when used with doppler and carries hardly any risk.** We have studied 85 men and 47 women aged 54 (SD 16) years with unexplained peripheral embolism (38) and/or stroke most probably due to a cerebral embolic event (94). All were examined by a
MAJOR ECHOCARDIOGRAPHIC FINDINGS
IN PATIENTS WITH
UNEXPLAINED EMBOLISM
PFO = patent foramen ovale, LASEC left atrial spontaneous echo contrast, LA LV left atnum and ventricle, LAA left atrial appendage. *On 21 panents only. =
=
=