600
4. Hudson
M, Pocknee R, Mowat MAG. D-lactic acidosis in short bowel
syndrome—an examination of possible mechanisms. QJ Med 1990; 74: 157-63. 5. Thurn JR,
Pierpont L, Ludvigsen CW, Eckfeldt JH. D-lactate encephalopathy. Am J Med 1985; 79: 717-21. 6. Mason PD. Metabolic acidosis due to D-lactate. Br Med J 1986; 292: 1105-06. 7. McNeil I. Nutritional implications of human and mammalian large intestinal function. World Rev Nutr Dietet 1988; 56: 1-42. 8. Dunlop RH, Hammond PB. D-lactic acidosis of ruminants. Ann N Y Acad Sci 1965; 119: 1109-32. 9. van Eys J, Judge MA, Judd J, Hill W, Bozian RC, Abrahams S. A reinvestigation of methylglyoxal accumulation in thiamine deficiency. J Nutr 1962; 76: 375-84.
SSPE IN THE DEVELOPING WORLD Patients with subacute sclerosing panencephalitis (SSPE) present a distressing picture, all too frequent in developing countries. The underlying pathological change, a progressive degeneration of the central nervous system, is manifested in various neurological signs-behavioural
changes, developmental deterioration, ataxia, myoclonic seizures, visual disorders, spasticity, and decerebrate rigidity.1 Characteristically, these features appear insidiously in a child aged five to fifteen who had measles many years previously. The doctor in a developing country has to make a tentative diagnosis because confirmation requires the demonstration of high-titre measles antibody in the cerebrospinal fluid,2and this test is not usually available. Differential diagnoses include cerebral tumours, other neurodegenerative conditions, and human immunodeficiency virus infection. When antibody tests have been applied in developing countries, SSPE has been shown
for a substantial fraction of childhood neurodegenerative conditions. 4-7 Chemotherapy is ineffective,l and the clinical course is relentlessly downhill until death months or years later. SSPE is a rare complication of measles-annual incidence ranges from under 0.1cases7,8 to 5 or 6 cases4 per million population. The wide range partly reflects difficulties in diagnosis and case-finding and also illustrates the relative degrees of success and failure of measles control achieved by different countries."’ The exact pathogenesis is unknown. Some invasion of the central nervous system is common in measles,l but it is unclear why SSPE affects an unfortunate few children, a long-time (5-10 years) after the acute infection. Children infected in the first 2 years are more at risk and case-series have consistently shown an excess of boys 49 but this apparent age and sex bias may merely reflect another more important factor concerning the dose of measles received at exposure." A higher incidence of SSPE would be expected in developing countries because there is more circulating measles10 and attack rates are higher in the first two years of life. 12 Survey results confirm this suggestion,4-7 although few studies have been conducted in sub-Saharan Africa.13 Mass measles vaccination is effective in reducing SSPE incidence in both developing and industrialised countries.9,14,15 Fears that measles vaccine might itself cause SSPE have been shown to be groundless9,15-it is more hazardous to remain unimmunised.1’ SSPE is another strong reason for promoting mass immunisation, especially since the demonstration that high-titre Edmonston-Zagreb measles vaccine given in the first year is both safe16 and effective17 in preventing early measles. The Global Advisory Group of WHO’s Expanded Programme on Immunisation has recommended that this vaccine is given at six months of to account
age where early transmission is a hazard.12 SSPE intensifies the challenge to governments, programme managers, and donors in developing countries to apply the
recommendation with
speed and vigour.
HC, Marshall WC. Measles. In: Weatherall DJ, Ledingham JGG, Warrell DA, eds. Oxford textbook of medicine, 2nd ed. Oxford: Oxford University Press, 1987: 5.89-93. 2. Norrby E. Measles virus. In: Lenette EH, Balows A, Hausler WJ, Shadomy HJ, eds. Manual of clinical microbiology. Washington, DC: American Society of Microbiology, 1985: 772. 3. Epstein LG, Sharer LR, Oleske JM, et al. Neurologic manifestations of human immunodeficiency virus infection in children. Pediatrics 1986; 1. Whittle
78: 678-87. 4. Cernescu S,
Milea S. Epidemiology of subacute sclerosing in Romania between 1976-1982. Virologic 1983; 34:
panencephalitis 239-50. 5. Yalaz K, Anlar
B, Renda Y, Aysun S, Topcu M, Ozdirim E. Subacute sclerosing panencephalitis in Turkey: epidemiological features. J Trop
Pediatr 1988; 34: 301-05. 6. Bakir TM, Hossain A, Ramia S, Sinha NP. Seroepidemiology of mumps, measles and subacute sclerosing panencephalitis in Saudi Arabia. J Trop Pediatr 1988; 34: 254-56. 7. Radhakrishnan K, Thacker AK, Maloo JC, Gerryo SE, Mousa ME. Descriptive epidemiology of some rare neurological diseasesin Benghazi, Libya. Neuroepidemiology 1988; 7: 159-64. 8. Hinman AR, Orenstein WA, Bloch AB, et al. Impact of measles in the United States. Rev Infect Dis 1983; 5: 439-44. 9. Miller CL. Current impact of measles in the United Kingdom. Rev Infect Dis 1983; 5: 427-32. 10. Grant JP. The state of the world’s children 1990. Oxford: Oxford
University Press, 1990. Aaby P, Bukh J, Lisse IM, Smits AJ. Risk factors in subacute sclerosing panencephalitis; age and sex-dependent host reactions or intensive exposure. Ref Infect Dis 1984; 6: 239-50. 12. Hall AJ, Greenwood BM, Whittle H. Modern vaccines: practice in developing countries. Lancet 1990; 335: 774-77. 13. Tukei PM, Kenya PR, Ensering J. An epidemiological study of subacute sclerosing panencephalitis in Kenya. East Afr Med J 1983; 60:34-38. 14. Vucenovic V, Vranjesevic D. SSPE—epidemiology and measles
11.
vaccination: our cases. Neurol 1989; 38: 23-31. 15. Bloch AB, Orenmstein WA, Stetler HC, et al. Health impact of measles vaccination in the United States. Pediatrics 1985; 76: 524-32. 16. Whittle H, Hanlon P, O’Neill K, et al. Trial of high-dose EdmonstonZagreb measles vaccine in The Gambia: antibody response and side-effects. Lancet 1988; ii: 811-14. 17. Aaby P, Jensen TG, Hansek HL, et al. Trial of high-dose EdmonstonZagreb measles in Guinea-Bissau: protective efficacy. Lancet 1988; ii: 809-11.
NHS NURSING HOMES
provided for dependent old people in long-stay in Britain is not a source of national pride. wards hospital Frail elderly individuals who cannot live at home tend to be housed in outmoded buildings, often some distance from their families.! The physical environment can be depressing-single rooms are rare; bathing and toilet facilities are usually inadequate; and there is uniformity of decor and an unmistakably institutional an-nosphere.’Z Although long-stay wards are home to those who are nursed there, half have no dining room and it is exceptional for residents to have items of their own furniture.3 Many continuing-care patients are denied basic freedoms. They have to get up early and go to bed at set times, visiting hours are restricted, and much of the day is spent sitting, doing nothing. Staffing levels are low and the nurses would like to have better training, support, and recognition. Geriatricians have not always taken their responsibilities for long-stay The
care
patients very seriously.4 The Health Care Research Unit at Newcastle University has published its evaluation of an alternative model of long-term nursing care.5,6 The first three National Health
601
nursing homes (in Sheffield, Fleetwood, and Portsmouth) that were assessed are small converted buildings in residential areas that provide a more domestic environment and better facilities than most long-stay wards.3 Patients are not the responsibility of consultants but are managed by nurses, who contact general practitioners Service
when necessary. How do these homes compare with traditional extended-care wards? There are no differences in self-perceived wellbeing of patients; observed changes in mental state and behavioural ability, satisfaction with the food; or numbers of visitors. However, most patients prefer the nursing homes, in which they enjoy more autonomy and there is greater social interaction. Residents can see visitors in the privacy of their own rooms and they are more likely to wear their own clothes, to have personal belongings, and to take their meals in a dining room. Choice of bedtime is left to the individual. They are encouraged to express their views, and their opinions about the staff and environment are
generally positive. In terms of quality of life, this style of long-term care has clear advantages over the traditional medical model. What about quality of care? Mortality rates are similar in the two settings. However, the absence of a multidisciplinary team from nursing homes may explain differences in dependence and discharge. Long-stay patients should be encouraged to do as much as possible for themselves.’ Although those in nursing homes were less disabled, they required more help with dressing than their counterparts in long-stay wards. This observation may reflect the lack
or
dearth of
occupational therapy in the three homes. Only 2 of 236 old people were discharged from an NHS home. By contrast, over 10% of those in geriatric wards went to other (non-NHS) institutions and 9 people returned home. These "late developers" are an important group, who serve to underline the fact that long-term care is not static care. Regular review by a team that includes doctors, therapists, and social workers as well as nurses ought to ensure that independence is encouraged and standards and morale are maintained. This important work has been time-consuming and costly. The results have been analysed and presented carefully and they deserve to be widely read. The study can be criticised on the grounds of randomisation, comparability, and sample size. The old people in one NHS nursing home were less frail, disabled, and confused than those in hospital,S and pilot homes had better levels of nursing staff than the long-stay wards.8 A larger sample size will improve the statistical power of future studies. One cannot extrapolate from these results to the burgeoning numbers of private nursing homes, which usually cater for a smaller proportion of dependent and confused patients9 and often do not provide single rooms.1o Overall the study suggests that small, homely, community-based units in which residents are allowed privacy and choice and in which they receive personalised care are usually preferable to continuing-care accommodation in old-fashioned hospital wards.
1. Coni NK. Private homes for elderly patients. Lancet 1987; ii: 102. 2. Horrocks P. The components of a comprehensive district health service for elderly people—a personal view. Age Ageing 1986; 15: 321-42. 3. Bond J, Atkinson A, Bond S, Donaldson C, Gregson BA, Hally MR. Evaluation of long-stay accommodation for elderly people: first interim report. Vol 2. Preliminary report of base-line survey. Health Care Research Unit report no 29. University of Newcastle-upon-Tyne, 1986.
4. Evans JG. National Health Service nursing homes. Age Ageing 1989; 18: 289-91. 5. Bond J, Gregson BA, Atkinson A. Measurement of outcomes within a multicentred randomised controlled trial in the evaluation of the experimental NHS nursing homes. Age Ageing 1989; 18: 292-302. 6. Bond S, Bond J. Outcomes of care within a multiple-case study in the evaluation of the experimental National Health Service nursing homes.
Age Ageing 1990; 19: 11-18. JR. Living in hospital. The social needs of people in long-term care. London: King Edward’s Hospital Fund, 1975. 8. Bond J, Bond S, Donaldson C, Gregson B, Atkinson A. Evaluation of continuing-care accommodation for elderly people. Vol 7. Overview of an evaluation of continuing-care accommodation for older people. Health Care Research Unit report no 38. University of Newcastleupon-Tyne, 1989. 9. Bennett J. Private nursing homes: contribution to long stay care of the elderly in the Brighton Health District. Br Med J 1986; 293: 867-70. 10. Primrose WR, Capewell AE. A survey of registered nursing homes within the city of Edinburgh. J R Coll Gen Pract 1986; 36: 125-28. 7. Elliott
NEUROLOGICAL COMPLICATIONS OF DOMOIC ACID INTOXICATION In
Canada, during November and December, 1987, there
was
an
outbreak of
an
acute
illness associated with
gastrointestinal and neurological disturbance. The common factor between the several hundred patients involved was consumption, within the previous 24 hours, of mussels that had originated from one of three estuaries on Prince Edward Island. The responsible toxin was shown to be domoic acid, produced by the marine vegetation Nitzschia pungens. The epidemiological detective work that led to characterisation of the disorder has now been described, as have details of the neurological complications of the illness.2 During the acute phase gastrointestinal disturbance was the commonest complaint. Other features included haemodynamic instability, piloerection, pupillary changes, and profuse bronchial secretions. Confusion, coma, seizures, disordered eye movements, and mutism were the prominent neurological findings. The long-term neurological complications were perhaps the most interesting aspect of the outbreak. Some patients had an amnesic syndrome with relative preservation of other cognitive functions. The pattern of memory loss resembled that described earlier in a patient who had undergone bilateral excision of the amygdala and hippocampus. Neuropathological studies in four patients showed neuronal necrosis and loss, which were most pronounced in the hippocampus, amygdala, and parts of the thalamus. Limb weakness developed in several patients and neurophysiological studies indicated either anterior horn cell involvement or a diffuse axonopathy. Domoic acid is structurally similar to the excitatory neurotransmitter glutamate and has a greater binding affinity for the kainate type of glutamate receptor than does kainic acid. In laboratory animals kainic acid induces excitability, limbic seizures, and neuronal degeneration in the hippocampus, amygdala, and thalamus similar to that in the patients. No further cases of intoxication have been reported. Mussels are now tested for the presence of domoic acid before commercial distribution.
1. Perl TM, Bedard L, Kosatsky T, et al. An outbreak of toxic encephalopathy caused by eating mussels contaminated with domoic acid. N Engl J Med 1990; 322: 1775-80. 2. Teitelbaum JS, Zatorre RJ, Carpenter S, et al. Neurologic sequelae of domoic acid intoxication due to the ingestion of contaminated mussels. N Engl J Med 1990; 322: 1781-87.
4. Hudson
M, Pocknee R, Mowat MAG. D-lactic acidosis in short bowel
syndrome—an examination of possible mechanisms. QJ Med 1990; 74: 157-63. 5. Thurn JR,
Pierpont L, Ludvigsen CW, Eckfeldt JH. D-lactate encephalopathy. Am J Med 1985; 79: 717-21. 6. Mason PD. Metabolic acidosis due to D-lactate. Br Med J 1986; 292: 1105-06. 7. McNeil I. Nutritional implications of human and mammalian large intestinal function. World Rev Nutr Dietet 1988; 56: 1-42. 8. Dunlop RH, Hammond PB. D-lactic acidosis of ruminants. Ann N Y Acad Sci 1965; 119: 1109-32. 9. van Eys J, Judge MA, Judd J, Hill W, Bozian RC, Abrahams S. A reinvestigation of methylglyoxal accumulation in thiamine deficiency. J Nutr 1962; 76: 375-84.
SSPE IN THE DEVELOPING WORLD Patients with subacute sclerosing panencephalitis (SSPE) present a distressing picture, all too frequent in developing countries. The underlying pathological change, a progressive degeneration of the central nervous system, is manifested in various neurological signs-behavioural
changes, developmental deterioration, ataxia, myoclonic seizures, visual disorders, spasticity, and decerebrate rigidity.1 Characteristically, these features appear insidiously in a child aged five to fifteen who had measles many years previously. The doctor in a developing country has to make a tentative diagnosis because confirmation requires the demonstration of high-titre measles antibody in the cerebrospinal fluid,2and this test is not usually available. Differential diagnoses include cerebral tumours, other neurodegenerative conditions, and human immunodeficiency virus infection. When antibody tests have been applied in developing countries, SSPE has been shown
for a substantial fraction of childhood neurodegenerative conditions. 4-7 Chemotherapy is ineffective,l and the clinical course is relentlessly downhill until death months or years later. SSPE is a rare complication of measles-annual incidence ranges from under 0.1cases7,8 to 5 or 6 cases4 per million population. The wide range partly reflects difficulties in diagnosis and case-finding and also illustrates the relative degrees of success and failure of measles control achieved by different countries."’ The exact pathogenesis is unknown. Some invasion of the central nervous system is common in measles,l but it is unclear why SSPE affects an unfortunate few children, a long-time (5-10 years) after the acute infection. Children infected in the first 2 years are more at risk and case-series have consistently shown an excess of boys 49 but this apparent age and sex bias may merely reflect another more important factor concerning the dose of measles received at exposure." A higher incidence of SSPE would be expected in developing countries because there is more circulating measles10 and attack rates are higher in the first two years of life. 12 Survey results confirm this suggestion,4-7 although few studies have been conducted in sub-Saharan Africa.13 Mass measles vaccination is effective in reducing SSPE incidence in both developing and industrialised countries.9,14,15 Fears that measles vaccine might itself cause SSPE have been shown to be groundless9,15-it is more hazardous to remain unimmunised.1’ SSPE is another strong reason for promoting mass immunisation, especially since the demonstration that high-titre Edmonston-Zagreb measles vaccine given in the first year is both safe16 and effective17 in preventing early measles. The Global Advisory Group of WHO’s Expanded Programme on Immunisation has recommended that this vaccine is given at six months of to account
age where early transmission is a hazard.12 SSPE intensifies the challenge to governments, programme managers, and donors in developing countries to apply the
recommendation with
speed and vigour.
HC, Marshall WC. Measles. In: Weatherall DJ, Ledingham JGG, Warrell DA, eds. Oxford textbook of medicine, 2nd ed. Oxford: Oxford University Press, 1987: 5.89-93. 2. Norrby E. Measles virus. In: Lenette EH, Balows A, Hausler WJ, Shadomy HJ, eds. Manual of clinical microbiology. Washington, DC: American Society of Microbiology, 1985: 772. 3. Epstein LG, Sharer LR, Oleske JM, et al. Neurologic manifestations of human immunodeficiency virus infection in children. Pediatrics 1986; 1. Whittle
78: 678-87. 4. Cernescu S,
Milea S. Epidemiology of subacute sclerosing in Romania between 1976-1982. Virologic 1983; 34:
panencephalitis 239-50. 5. Yalaz K, Anlar
B, Renda Y, Aysun S, Topcu M, Ozdirim E. Subacute sclerosing panencephalitis in Turkey: epidemiological features. J Trop
Pediatr 1988; 34: 301-05. 6. Bakir TM, Hossain A, Ramia S, Sinha NP. Seroepidemiology of mumps, measles and subacute sclerosing panencephalitis in Saudi Arabia. J Trop Pediatr 1988; 34: 254-56. 7. Radhakrishnan K, Thacker AK, Maloo JC, Gerryo SE, Mousa ME. Descriptive epidemiology of some rare neurological diseasesin Benghazi, Libya. Neuroepidemiology 1988; 7: 159-64. 8. Hinman AR, Orenstein WA, Bloch AB, et al. Impact of measles in the United States. Rev Infect Dis 1983; 5: 439-44. 9. Miller CL. Current impact of measles in the United Kingdom. Rev Infect Dis 1983; 5: 427-32. 10. Grant JP. The state of the world’s children 1990. Oxford: Oxford
University Press, 1990. Aaby P, Bukh J, Lisse IM, Smits AJ. Risk factors in subacute sclerosing panencephalitis; age and sex-dependent host reactions or intensive exposure. Ref Infect Dis 1984; 6: 239-50. 12. Hall AJ, Greenwood BM, Whittle H. Modern vaccines: practice in developing countries. Lancet 1990; 335: 774-77. 13. Tukei PM, Kenya PR, Ensering J. An epidemiological study of subacute sclerosing panencephalitis in Kenya. East Afr Med J 1983; 60:34-38. 14. Vucenovic V, Vranjesevic D. SSPE—epidemiology and measles
11.
vaccination: our cases. Neurol 1989; 38: 23-31. 15. Bloch AB, Orenmstein WA, Stetler HC, et al. Health impact of measles vaccination in the United States. Pediatrics 1985; 76: 524-32. 16. Whittle H, Hanlon P, O’Neill K, et al. Trial of high-dose EdmonstonZagreb measles vaccine in The Gambia: antibody response and side-effects. Lancet 1988; ii: 811-14. 17. Aaby P, Jensen TG, Hansek HL, et al. Trial of high-dose EdmonstonZagreb measles in Guinea-Bissau: protective efficacy. Lancet 1988; ii: 809-11.
NHS NURSING HOMES
provided for dependent old people in long-stay in Britain is not a source of national pride. wards hospital Frail elderly individuals who cannot live at home tend to be housed in outmoded buildings, often some distance from their families.! The physical environment can be depressing-single rooms are rare; bathing and toilet facilities are usually inadequate; and there is uniformity of decor and an unmistakably institutional an-nosphere.’Z Although long-stay wards are home to those who are nursed there, half have no dining room and it is exceptional for residents to have items of their own furniture.3 Many continuing-care patients are denied basic freedoms. They have to get up early and go to bed at set times, visiting hours are restricted, and much of the day is spent sitting, doing nothing. Staffing levels are low and the nurses would like to have better training, support, and recognition. Geriatricians have not always taken their responsibilities for long-stay The
care
patients very seriously.4 The Health Care Research Unit at Newcastle University has published its evaluation of an alternative model of long-term nursing care.5,6 The first three National Health
601
nursing homes (in Sheffield, Fleetwood, and Portsmouth) that were assessed are small converted buildings in residential areas that provide a more domestic environment and better facilities than most long-stay wards.3 Patients are not the responsibility of consultants but are managed by nurses, who contact general practitioners Service
when necessary. How do these homes compare with traditional extended-care wards? There are no differences in self-perceived wellbeing of patients; observed changes in mental state and behavioural ability, satisfaction with the food; or numbers of visitors. However, most patients prefer the nursing homes, in which they enjoy more autonomy and there is greater social interaction. Residents can see visitors in the privacy of their own rooms and they are more likely to wear their own clothes, to have personal belongings, and to take their meals in a dining room. Choice of bedtime is left to the individual. They are encouraged to express their views, and their opinions about the staff and environment are
generally positive. In terms of quality of life, this style of long-term care has clear advantages over the traditional medical model. What about quality of care? Mortality rates are similar in the two settings. However, the absence of a multidisciplinary team from nursing homes may explain differences in dependence and discharge. Long-stay patients should be encouraged to do as much as possible for themselves.’ Although those in nursing homes were less disabled, they required more help with dressing than their counterparts in long-stay wards. This observation may reflect the lack
or
dearth of
occupational therapy in the three homes. Only 2 of 236 old people were discharged from an NHS home. By contrast, over 10% of those in geriatric wards went to other (non-NHS) institutions and 9 people returned home. These "late developers" are an important group, who serve to underline the fact that long-term care is not static care. Regular review by a team that includes doctors, therapists, and social workers as well as nurses ought to ensure that independence is encouraged and standards and morale are maintained. This important work has been time-consuming and costly. The results have been analysed and presented carefully and they deserve to be widely read. The study can be criticised on the grounds of randomisation, comparability, and sample size. The old people in one NHS nursing home were less frail, disabled, and confused than those in hospital,S and pilot homes had better levels of nursing staff than the long-stay wards.8 A larger sample size will improve the statistical power of future studies. One cannot extrapolate from these results to the burgeoning numbers of private nursing homes, which usually cater for a smaller proportion of dependent and confused patients9 and often do not provide single rooms.1o Overall the study suggests that small, homely, community-based units in which residents are allowed privacy and choice and in which they receive personalised care are usually preferable to continuing-care accommodation in old-fashioned hospital wards.
1. Coni NK. Private homes for elderly patients. Lancet 1987; ii: 102. 2. Horrocks P. The components of a comprehensive district health service for elderly people—a personal view. Age Ageing 1986; 15: 321-42. 3. Bond J, Atkinson A, Bond S, Donaldson C, Gregson BA, Hally MR. Evaluation of long-stay accommodation for elderly people: first interim report. Vol 2. Preliminary report of base-line survey. Health Care Research Unit report no 29. University of Newcastle-upon-Tyne, 1986.
4. Evans JG. National Health Service nursing homes. Age Ageing 1989; 18: 289-91. 5. Bond J, Gregson BA, Atkinson A. Measurement of outcomes within a multicentred randomised controlled trial in the evaluation of the experimental NHS nursing homes. Age Ageing 1989; 18: 292-302. 6. Bond S, Bond J. Outcomes of care within a multiple-case study in the evaluation of the experimental National Health Service nursing homes.
Age Ageing 1990; 19: 11-18. JR. Living in hospital. The social needs of people in long-term care. London: King Edward’s Hospital Fund, 1975. 8. Bond J, Bond S, Donaldson C, Gregson B, Atkinson A. Evaluation of continuing-care accommodation for elderly people. Vol 7. Overview of an evaluation of continuing-care accommodation for older people. Health Care Research Unit report no 38. University of Newcastleupon-Tyne, 1989. 9. Bennett J. Private nursing homes: contribution to long stay care of the elderly in the Brighton Health District. Br Med J 1986; 293: 867-70. 10. Primrose WR, Capewell AE. A survey of registered nursing homes within the city of Edinburgh. J R Coll Gen Pract 1986; 36: 125-28. 7. Elliott
NEUROLOGICAL COMPLICATIONS OF DOMOIC ACID INTOXICATION In
Canada, during November and December, 1987, there
was
an
outbreak of
an
acute
illness associated with
gastrointestinal and neurological disturbance. The common factor between the several hundred patients involved was consumption, within the previous 24 hours, of mussels that had originated from one of three estuaries on Prince Edward Island. The responsible toxin was shown to be domoic acid, produced by the marine vegetation Nitzschia pungens. The epidemiological detective work that led to characterisation of the disorder has now been described, as have details of the neurological complications of the illness.2 During the acute phase gastrointestinal disturbance was the commonest complaint. Other features included haemodynamic instability, piloerection, pupillary changes, and profuse bronchial secretions. Confusion, coma, seizures, disordered eye movements, and mutism were the prominent neurological findings. The long-term neurological complications were perhaps the most interesting aspect of the outbreak. Some patients had an amnesic syndrome with relative preservation of other cognitive functions. The pattern of memory loss resembled that described earlier in a patient who had undergone bilateral excision of the amygdala and hippocampus. Neuropathological studies in four patients showed neuronal necrosis and loss, which were most pronounced in the hippocampus, amygdala, and parts of the thalamus. Limb weakness developed in several patients and neurophysiological studies indicated either anterior horn cell involvement or a diffuse axonopathy. Domoic acid is structurally similar to the excitatory neurotransmitter glutamate and has a greater binding affinity for the kainate type of glutamate receptor than does kainic acid. In laboratory animals kainic acid induces excitability, limbic seizures, and neuronal degeneration in the hippocampus, amygdala, and thalamus similar to that in the patients. No further cases of intoxication have been reported. Mussels are now tested for the presence of domoic acid before commercial distribution.
1. Perl TM, Bedard L, Kosatsky T, et al. An outbreak of toxic encephalopathy caused by eating mussels contaminated with domoic acid. N Engl J Med 1990; 322: 1775-80. 2. Teitelbaum JS, Zatorre RJ, Carpenter S, et al. Neurologic sequelae of domoic acid intoxication due to the ingestion of contaminated mussels. N Engl J Med 1990; 322: 1781-87.
